The paper presents a new approach to the design of the classical PD controller for the plant in the closed loop control system. Proposed controller has two unknown adjustable parameters which are designed by the algebraic method in the two dimensional parameter space, by using the newly discovered characteristic polynomial of the row nondegenerate full transfer function matrix. The system relative stability, in regard to the chosen damping coefficient is achieved. The optimality criterion is the minimal value of the performance index and sum of squared error is taken as an objective function. The output error used in the performance index is influenced by all actions on the system at the same time: by nonzero initial conditions and by nonzero inputs. In the classical approach the output error is influenced only by nonzero inputs.
Experimental results confirm that by taking into account nonzero initial conditions, an optimal solution is obtained, which is not the case with the classical method where
optimization is performed at zero initial conditions

As one of the most promising topics in complex control processes, data-driven techniques have been widely used in numerous industrial sectors and have developed over the past two decades. In addition, the fractional-order controller has become more attractive in applied studies. In this article, a fractional integral control is implemented for a rotary flexible joint system. Moreover, an adjusted virtual reference feedback tuning (VRFT) technique is used to tune the fractional-order integrator. In this method, fractional integral control is designed based on state feedback control. Then, VRFT is adjusted and applied to the fractional integral controller. The effectiveness of the proposed adjusted VRFT method is discussed and presented through simulation and experimental results. The tracking performance of the rotary arm and the minimization of the vibration tip is evaluated based on the proposed method. In this article, the comparison of our proposed VRFT fractional scheme is made with the classical state feedback as well as a recently developed state feedback-based fractional order integral (SF-FOI) controller. The current investigations determine the performance improvement of our proposed scheme of comparable structure to the recent SF-FOI, with the introduction of the VRFT to the SF-FOI scheme.

Compare to rigid manipulators, flexible link manipulators (FLM) have the advantage of being lightweight and low energy consumption, which makes them have increasing demands across the industrial and aerospace world. Inverse dynamics-based control has been applied widely in rigid manipulators. However, the natural undamped behavior of FLM's internal dynamics hinders the direct use of inverse dynamics-based control. In this paper, an inverse dynamics-based control with parameter adaptation has been proposed, which is designed according to a redefined dynamic model with uncertainties for achieving good tip-tracking with good vibration attenuation as well. The proposed controller consists of model compensation based on inverse dynamics, feedback control, and internal control. The stability of the closed-loop system has been proved through Lyapunov theory. The experimental results indicate best performances in both slow and fast point-to-point motion with the proposed control.

As the nonlinear predictive control model (NMPC) has evolved so far, most studies are confined to the slow dynamic nonlinear method, the study difficulty for the general nonlinear systems is mainly derived from optimization algorithm analysis. In fact, most reality control systems are nonlinear and are likely to have limitations. This paper proposed the population selection based improved particle swarm optimization (PS-IPSO) to minimize the computational time of the NMPC algorithm. In the PS-IPSO, the population selection step based on the ranking of population accordance with _tness function evaluation is implemented.
Via simulation results, the improved algorithm's effectiveness is determined by applying it to the highly nonlinear fast dynamic single rotary inverted pendulum (SRIP)system. The solution presented in the paper is computationally feasible for smaller sampling times.

Sophisticated automation is dependent upon industrial robots with precise position control servomotors. In the present work, a fractional order fuzzy PID controller (FOFPID) was designed to improve the position control response of a rotary servo system. The control errors and their fractional derivatives were applied as input scaling factors to the fuzzy logic controller (FLC). Fuzzy inference system (FIS) was employed to restrict performance indices in control signals. FOFPID performance for a Quanser servomotor was compared against PID, fractional order PID and fuzzy PID (FPID) controllers in terms of both simulations and hardware implementation. The controller performance evaluation metrics included time domain characteristics such as rise, peak, settling times and over / undershoots. The integral absolute and integral time absolute errors were also evaluated for comparisons among the different controllers. Results establish that only the FOFPID controller achieves zero percent over and undershoots. It also attains better set point tracking over other controllers. Thus, FOFPID controller is the key to precision robotics in the smart factories of tomorrow.

Flexible robots are subject of many research-works since their advantages in terms of safety, compliance, low energy consumption, manoeuvrability, high payload to manipulator weight ratio, low cost, and high speed. However, the flexibility of manipulator’s links or joints and the under-actuation leads to complexity in the modelling and control. To deal with this problem, a sliding mode control is designed and applied to a presented model of the system. So, this paper presents the modelling of flexible joint manipulator, the design of adequate sliding mode controller which can stabilize the flexible joint manipulator. The robust tracking performance will be proved in the simulation.

Vibration control techniques are of a great importance in Aerospace Engineering, Automotive Engineering, Mechanical Engineering, and Robotics, providing stability and well damped behavior to control systems. In this context, this work aims to the development of a mathematical model for the slewing flexible structure, considering both flexible and rigid body motion. In order to obtain the equations of motion, the Euler-Lagrange method is considered. The experimental system consists of a flexible beam with a free end, and the other end clamped to a dc motor axis. The angular position of the motor axis is measured and sampled. The state observer is designed in order to estimate the flexible body motion and the angular speed of the rigid body motion, which are important signals in the feedback of vibration control systems. The mathematical model and the sate observer are experimentally validated. The expected results are the stabilization and damping of the vibration modes of the slewing flexible beam.

@article{zhang5_2020,
title = {Continuous PID-SMC based on improved EHGO for robot manipulators with limited state measurements},
author = {Zhang, X.; Li, H.; Li, G.; Chen, T.; Shan, J.},
journal = {Journal of the Franklin Institute},
year = {2020},
institution = {University of Electronic Science and Technology of China, China; York University, Canada},
abstract = {This paper focuses on the robust output feedback tracking control for n-DOF (degree-of-freedom) robot manipulators with limited state measurements. An improved extended high-gain observer (EHGO) is designed to estimate the unavailable states as well as the system uncertainty and disturbance. A novel control framework combining the improved EHGO and continuous PID-sliding mode controller (PID-SMC) is proposed. The Lyapunov approach is used to prove the effectiveness of the EHGO. Moreover, the stability and convergence of the closed-loop system are confirmed through the singular perturbation theory. Numerical simulation and experimental results are presented to show the performance of the proposed control scheme. },
language = {English},
publisher = {Elsevier Ltd.}
}

This paper focuses on the robust output feedback tracking control for n-DOF (degree-of-freedom) robot manipulators with limited state measurements. An improved extended high-gain observer (EHGO) is designed to estimate the unavailable states as well as the system uncertainty and disturbance. A novel control framework combining the improved EHGO and continuous PID-sliding mode controller (PID-SMC) is proposed. The Lyapunov approach is used to prove the effectiveness of the EHGO. Moreover, the stability and convergence of the closed-loop system are confirmed through the singular perturbation theory. Numerical simulation and experimental results are presented to show the performance of the proposed control scheme.

@article{mehedi_2020,
title = {Controlling a Rotary Servo Cart System Using Robust Generalized Dynamic Inversion},
author = {Mehedi, I.M.; Ansari, U.; Al-Saggaf, U.M.; Bajodah, A.H.},
journal = {International Journal of Robotics and Automation},
year = {2020},
volume = {35},
number = {1},
institution = {King Abdulaziz University, Saudi Arabia},
abstract = {This paper presents the design and implementation of the Robust Generalized Dynamic Inversion (RGDI) based position and speed control of the rotary servo cart system. The RGDI control law comprises the two sub-parts, i.e., the equivalent control part and the robust control part. The equivalent control part represents the conventional form of the Generalized Dynamic Inversion control, in which dynamical constraints based on the deviation functions of angular position and its rate are formulated that encapsulates the control objectives. The control law is realized by inverting the constraint dynamics using dynamically scaled generalized inversion. The robust control part consists of an additional term based on the sliding mode principle that makes the control law robust with respect to the parametric fluctuation and outward disturbances while providing improved tracking performance. The closed-loop stability of RGDI control is ensured using the positive definite Lyapunov candidate function, which will guarantee globally practical stable tracking performance. Numerical simulations in Matlab/Simulink environment and the real-time experiments are performed on the Quanser’s SRV02 rotary servo cart platform. It exhibits better tracking performance through simulation and the experimental results. Robustness attributes to the proposed control law under the influence of the parametric uncertainties and external disturbances. },
keywords = {Generalized dynamic inversion, servo cart system, Lyapunov stability, sliding mode control, robust control},
language = {English},
publisher = {ACTA Press}
}

This paper presents the design and implementation of the Robust Generalized Dynamic Inversion (RGDI) based position and speed control of the rotary servo cart system. The RGDI control law comprises the two sub-parts, i.e., the equivalent control part and the robust control part. The equivalent control part represents the conventional form of the Generalized Dynamic Inversion control, in which dynamical constraints based on the deviation functions of angular position and its rate are formulated that encapsulates the control objectives. The control law is realized by inverting the constraint dynamics using dynamically scaled generalized inversion. The robust control part consists of an additional term based on the sliding mode principle that makes the control law robust with respect to the parametric fluctuation and outward disturbances while providing improved tracking performance. The closed-loop stability of RGDI control is ensured using the positive definite Lyapunov candidate function, which will guarantee globally practical stable tracking performance. Numerical simulations in Matlab/Simulink environment and the real-time experiments are performed on the Quanser’s SRV02 rotary servo cart platform. It exhibits better tracking performance through simulation and the experimental results. Robustness attributes to the proposed control law under the influence of the parametric uncertainties and external disturbances.

A gesture is a form of non-verbal communication in which body actions communicate some particular messages. Due to the high processing capacity of today’s computers, hand gesture recognition systems can be used to simplify interactions with electronic devices. In this paper, a hand posture recognition system was implemented, which is able to recognize five posture of a hand. The five postures consist of how many fingers are shown, and then, this information is used to control the position of a DC motor. Hand gestures are recognized by an image processing system that uses a neural network implemented on a microcontroller.

In this paper, we will report about the adaption of our control education by implementation of Rapid-ControlPrototyping methods in our study program. The first step in this adaption process was a detailed analysis of the main difficulties for students with respect to the implementation of a control task. It turned out that the continuous usage of the proposed software tool chain (MATLAB/Simulink) in class presents a goaloriented approach when finally implementing a control task also in the lab. We point the students to use MATLAB/Simulink for controller design, simulation and plant identification (data acquisition task) and likewise to also deploy the controller on the specified hardware. Thus, Rapid-Control-Prototyping is a process that allows students to develop, modify and test control strategies on a real-world system. As a main result, we re-designed a specific lab exercise related to digital control in the Bachelor program: we introduced a low-cost rapid prototyping system based on Arduino Uno for posion control of a DC-motor. The paper also includes the adaption of a course “Embedded Control Systems” in the consecutive Master program following the idea of integrating lectures with exercises.

@article{de_2020,
title = {Nature Inspired Algorithm Based Optimal Type-2 Fuzzy Controller with Real-Time Validation on Servo System},
author = {De, R.R.; Mudi, R.K.; Dey, C},
journal = {International Journal of Electrical Engineering & Technology},
year = {2020},
volume = {11},
number = {2},
institution = {Jadavpur University, India; University of Calcutta, India},
abstract = {Performance of three well-known nature inspired algorithms like genetic algorithm (GA), particle swarm optimization (PSO), and differential evolution algorithm (DE) towards selection for optimal input and output scaling factors of an interval type-2 fuzzy PID controller (IT2-FLC) is evaluated for servo position control system. Optimal values of the input and output scaling factors for IT2-FLC are obtained through minimization of the objective function designed involving controller performance indices – percentage overshoot, settling time and integral time absolute error. Simulation study along with real-time experimental validation reveal the superiority of differential evolution algorithm (DE) based optimal IT2-FLC in terms of robustness and lesser noise sensitivity compared to other optimal IT2-FLCs. },
keywords = {genetic algorithm, particle swarm optimization, differential evolution algorithm, interval type-2 fuzzy logic controller, servo system},
language = {English},
pages = {44-53}
}

Performance of three well-known nature inspired algorithms like genetic algorithm (GA), particle swarm optimization (PSO), and differential evolution algorithm (DE) towards selection for optimal input and output scaling factors of an interval type-2 fuzzy PID controller (IT2-FLC) is evaluated for servo position control system. Optimal values of the input and output scaling factors for IT2-FLC are obtained through minimization of the objective function designed involving controller performance indices – percentage overshoot, settling time and integral time absolute error. Simulation study along with real-time experimental validation reveal the superiority of differential evolution algorithm (DE) based optimal IT2-FLC in terms of robustness and lesser noise sensitivity compared to other optimal IT2-FLCs.

@article{de-maity_2020,
title = {Nature-inspired and hybrid optimization algorithms on interval Type-2 fuzzy controller for servo processes: a comparative performance study},
author = {De (Maity), R.R.; Mudi, R.K.; Dey, C.},
journal = {SN Applied Sciences},
year = {2020},
institution = {Jadavpur University, India; University of Calcutta, India},
abstract = {In this paper, performance evaluations of six well-known nature-inspired algorithms have been reported containing genetic algorithm, cuckoo search, particle swarm optimization, differential evolution, bee colony, and combined particle swarm optimization and differential evolution (CPSODE) algorithms. Based on these optimization algorithms, input and output scaling factors of an interval Type-2 fuzzy PID controller (IT2-FLC) are chosen for closed-loop servo tracking. Optimal values of the scaling factors are chosen by minimization of the objective function which is defined based on the closed-loop controller performance criteria. A detailed comparative analysis is reported based on the simulation and experimental results. Performance analysis reveals that improved performance, reliability, robustness, and lesser noise sensitivity are reported by IT2-FLC with the optimal values obtained by the hybrid algorithm CPSODE. },
keywords = {Genetic algorithm (GA), Particle swarm optimization (PSO), Differential evolution (DE), Cuckoo search (CS), Bee colony (BC), Combined particle swarm optimization and differential evolution (CPSODE) algorithms, Interval Type-2 fuzzy controller, Servo tracking process},
language = {English},
publisher = {Springer Nature Switzerland}
}

In this paper, performance evaluations of six well-known nature-inspired algorithms have been reported containing genetic algorithm, cuckoo search, particle swarm optimization, differential evolution, bee colony, and combined particle swarm optimization and differential evolution (CPSODE) algorithms. Based on these optimization algorithms, input and output scaling factors of an interval Type-2 fuzzy PID controller (IT2-FLC) are chosen for closed-loop servo tracking. Optimal values of the scaling factors are chosen by minimization of the objective function which is defined based on the closed-loop controller performance criteria. A detailed comparative analysis is reported based on the simulation and experimental results. Performance analysis reveals that improved performance, reliability, robustness, and lesser noise sensitivity are reported by IT2-FLC with the optimal values obtained by the hybrid algorithm CPSODE.

@article{rhudy_2019,
title = {Breaking away from the traditional lab report: A technical email as a writing assignment in an engineering laboratory course},
author = {Rhudy, M.},
journal = {The Prompt Journal},
year = {2019},
volume = {3},
number = {2},
institution = {Pennsylvania State University, USA},
abstract = {Engineering laboratory courses often contain laboratory reports as writing assignments to be used as an assessment and grading tool for the course. While laboratory report writing is a useful skill, this article discusses an assignment which was used as an alternative to a traditional laboratory report within a dynamic systems laboratory course. This writing assignment is framed within the context of a hypothetical scenario involving a supervisor requesting a laboratory experiment to compare the effectiveness of two different designs for controlling the speed of a gearbox unit. Performance goals are specified by the ``customer'' so that students have a reference with which to frame their responses. Despite the shortened length of the writing assignment, students are forced to apply critical thinking and use evidence from their experiments to answer the posed question with a clear conclusion. },
language = {English}
}

Engineering laboratory courses often contain laboratory reports as writing assignments to be used as an assessment and grading tool for the course. While laboratory report writing is a useful skill, this article discusses an assignment which was used as an alternative to a traditional laboratory report within a dynamic systems laboratory course. This writing assignment is framed within the context of a hypothetical scenario involving a supervisor requesting a laboratory experiment to compare the effectiveness of two different designs for controlling the speed of a gearbox unit. Performance goals are specified by the ``customer'' so that students have a reference with which to frame their responses. Despite the shortened length of the writing assignment, students are forced to apply critical thinking and use evidence from their experiments to answer the posed question with a clear conclusion.

@article{wang_2019,
title = {Fixed-time consensus for uncertain multi-agent systems with actuator faults},
author = {Wang, Z.; Shan, J.},
journal = {Journal of the Franklin Institute},
year = {2019},
institution = {Xidian University, China; York University, Canada},
abstract = {This paper addresses the fixed-time consensus tracking problem for multi-agent Euler-Lagrange systems in the presence of model uncertainties, external disturbances, and actuator faults. Firstly, a new fixed-time terminal sliding surface is proposed to eliminate the singularity. Secondly, a distributed model-free fixed-time sliding mode control is designed to solve the consensus tracking problem for agents with Euler-Lagrange dynamics. It is proved that the proposed control scheme can ensure that the tracking errors converge to an arbitrary small bound centered on zero within fixed time and then go to zero asymptotically. Simulation and experiments are conducted to verify the effectiveness of the proposed approach. },
language = {English},
publisher = {Elsevier Ltd.}
}

This paper addresses the fixed-time consensus tracking problem for multi-agent Euler-Lagrange systems in the presence of model uncertainties, external disturbances, and actuator faults. Firstly, a new fixed-time terminal sliding surface is proposed to eliminate the singularity. Secondly, a distributed model-free fixed-time sliding mode control is designed to solve the consensus tracking problem for agents with Euler-Lagrange dynamics. It is proved that the proposed control scheme can ensure that the tracking errors converge to an arbitrary small bound centered on zero within fixed time and then go to zero asymptotically. Simulation and experiments are conducted to verify the effectiveness of the proposed approach.

@article{feng_2019,
title = {Integral-Type Sliding-Mode Control for a Class of Mechatronic Systems with Gain Adaptation},
author = {Feng, Y.; Zhou, M.; Han, Q.-L.; Han, F.; Cao, Z.; Ding, S.},
journal = {IEEE Transactions on Industrial Informatics},
year = {2019},
institution = {Harbin Institute of Technology, China; Harbin University of Science and Technology, China; Swinburne University of Technology, Australia; RMIT University, Australia},
abstract = {This paper proposes a continuous adaptive integral-type sliding-mode control approach for mechatronic systems by taking into consideration matched and unmatched uncertainties, and uncertainty in the control gain. Four different sliding-mode controllers are designed to enable: 1) the avoidance of the singularity by preventing differentiating the system states with fractional power; 2) the attenuation of the chattering by utilizing full-order sliding manifolds. The control gain adaptation in the full-order sliding-mode controller is presented to avoid the overestimation of the gain. With the continuous control in place, the mechatronic systems have a fast response with high precision. The soften action from carefully designed controllers with the gain adaptation guarantees the trajectories of the mechatronic systems to move smoothly and prevents damage to the mechanical components of the systems. Both the simulation and experimental results demonstrate the effectiveness and feasibility of the proposed control approach. },
issn = {1551-3203 },
keywords = {Sliding-mode control, Terminal sliding-mode, Mechatronic systems, Robustness},
language = {English},
publisher = {IEEE}
}

This paper proposes a continuous adaptive integral-type sliding-mode control approach for mechatronic systems by taking into consideration matched and unmatched uncertainties, and uncertainty in the control gain. Four different sliding-mode controllers are designed to enable: 1) the avoidance of the singularity by preventing differentiating the system states with fractional power; 2) the attenuation of the chattering by utilizing full-order sliding manifolds. The control gain adaptation in the full-order sliding-mode controller is presented to avoid the overestimation of the gain. With the continuous control in place, the mechatronic systems have a fast response with high precision. The soften action from carefully designed controllers with the gain adaptation guarantees the trajectories of the mechatronic systems to move smoothly and prevents damage to the mechanical components of the systems. Both the simulation and experimental results demonstrate the effectiveness and feasibility of the proposed control approach.

@article{aydogdu_2019,
title = {Kalman State Estimation and LQR Assisted Adaptive Control Of a Variable Loaded Servo System},
author = {Aydogdu, O.; Levent, M.L.},
journal = {Engineering, Technology & Applied Science Research},
year = {2019},
volume = {9},
number = {3},
institution = {Konya Technical University, Turkey; Hakkari University, Turkey},
abstract = {This study actualized a new hybrid adaptive controller design to increase the control performance of a variable loaded time-varying system. A structure in which LQR and adaptive control work together is proposed. At first, a Kalman filter was designed to estimate the states of the system and used with the LQR control method which is one of the optimal control servo system techniques in constant initial load. Then, for the variable loaded servo (VLS) system, the Lyapunov based adaptive control was added to the LQR control method which was inadequate due to the constant gain parameters. Thus, it was aimed to eliminate the variable load effects and increase the stability of the system. In order to show the effectiveness of the proposed method, a Quanser servo module was used in Matlab-Simulink environment. It is seen from the experimental results and performance measurements that the proposed method increases the system performance and stability by minimizing noise, variable load effect and steady-state error. },
issn = {2241-4487},
keywords = {adaptive control; Lyapunov method; LQR; Kalman filter; VLS system},
language = {English},
pages = {4125-4130}
}

This study actualized a new hybrid adaptive controller design to increase the control performance of a variable loaded time-varying system. A structure in which LQR and adaptive control work together is proposed. At first, a Kalman filter was designed to estimate the states of the system and used with the LQR control method which is one of the optimal control servo system techniques in constant initial load. Then, for the variable loaded servo (VLS) system, the Lyapunov based adaptive control was added to the LQR control method which was inadequate due to the constant gain parameters. Thus, it was aimed to eliminate the variable load effects and increase the stability of the system. In order to show the effectiveness of the proposed method, a Quanser servo module was used in Matlab-Simulink environment. It is seen from the experimental results and performance measurements that the proposed method increases the system performance and stability by minimizing noise, variable load effect and steady-state error.

@article{araujo_2019,
title = {NARX Model Identification Using Correntropy Criterion in the Presence of Non-Gaussian Noise},
author = {Araújo, Í.B.Q.; Guimarães, J.P.F.; Fontes, A.I.R.; Linhares, L.L.S.; Martins, A.M.; Araújo, F.M.U.},
journal = {Journal of Control, Automation and Electrical Systems},
year = {2019},
institution = {Federal University of Rio Grande do Norte, Brazil; Federal Institute of Rio Grande do Norte, Brazil},
abstract = {In past years, the system identification area has emphasized the identification of nonlinear dynamic systems. In this field, polynomial nonlinear autoregressive with exogenous (NARX) models are widely used due to flexibility and prominent representation capabilities. However, the traditional identification algorithms used for model selection and parameter estimation with NARX models have some limitation in the presence of non-Gaussian noise, since they are based on second-order statistics that tightly depend on the assumption of Gaussianity. In order to solve this dependence, a novel identification method called simulation correntropy maximization with pruning (SCMP) based on information theoretic learning is introduced by this paper. Results obtained in non-Gaussian noise environment in three experiments (numerical, benchmark data set and measured data from a real plant) are presented to validate the performance of the proposed approach when compared to other similar algorithms previously reported in the literature, e.g., forward regression with orthogonal least squares and simulation error minimization with pruning. The proposed SCMP method has shown increased accuracy and robustness for three different experiments. },
issn = {2195-3880},
keywords = {Nonlinear system identification, Polynomial NARX models, Model structure selection, Non-Gaussian noise, Maximum correntropy criterion },
language = {English},
publisher = {Springer US}
}

In past years, the system identification area has emphasized the identification of nonlinear dynamic systems. In this field, polynomial nonlinear autoregressive with exogenous (NARX) models are widely used due to flexibility and prominent representation capabilities. However, the traditional identification algorithms used for model selection and parameter estimation with NARX models have some limitation in the presence of non-Gaussian noise, since they are based on second-order statistics that tightly depend on the assumption of Gaussianity. In order to solve this dependence, a novel identification method called simulation correntropy maximization with pruning (SCMP) based on information theoretic learning is introduced by this paper. Results obtained in non-Gaussian noise environment in three experiments (numerical, benchmark data set and measured data from a real plant) are presented to validate the performance of the proposed approach when compared to other similar algorithms previously reported in the literature, e.g., forward regression with orthogonal least squares and simulation error minimization with pruning. The proposed SCMP method has shown increased accuracy and robustness for three different experiments.

@conference{abdullah_2018,
title = {A Formal Sensitivity Analysis for Laguerre Based Predictive Functional Control},
author = {Abdullah, M.; Rossiter, J.A.},
booktitle = {Control 2018 - 12th UKACC International Conference on Control},
year = {2018},
institution = {University of Sheffield, UK},
abstract = {A Laguerre Predictive Functional Control (LPFC) is a simple input shaping method, which can improve the prediction consistency and closed-loop performance of the conventional approach (PFC). However, it is well-known that an input shaping method, in general, will affect the loop sensitivity of a system. Hence, this paper presents a formal sensitivity analysis of LPFC by considering the effect of noise, unmeasured disturbance and parameter uncertainty. Sensitivity plots from bode diagrams and closed-loop simulation are used to illustrate the controller robustness and indicate that although LPFC often provides a better closed-loop tracking response and disturbance rejection, this may involve some trade-off with the sensitivity to noise and parameter uncertainty. Finally, to validate the practicality of the results, the sensitivity of the LPFC control law is illustrated on real-time laboratory hardware. },
keywords = {Predictive Control, PFC, Sensitivity Analysis, Laguerre function, Parameter Uncertainty, Noise, Disturbance},
language = {English},
publisher = {IEEE}
}

A Laguerre Predictive Functional Control (LPFC) is a simple input shaping method, which can improve the prediction consistency and closed-loop performance of the conventional approach (PFC). However, it is well-known that an input shaping method, in general, will affect the loop sensitivity of a system. Hence, this paper presents a formal sensitivity analysis of LPFC by considering the effect of noise, unmeasured disturbance and parameter uncertainty. Sensitivity plots from bode diagrams and closed-loop simulation are used to illustrate the controller robustness and indicate that although LPFC often provides a better closed-loop tracking response and disturbance rejection, this may involve some trade-off with the sensitivity to noise and parameter uncertainty. Finally, to validate the practicality of the results, the sensitivity of the LPFC control law is illustrated on real-time laboratory hardware.

@conference{abdullah2_2018,
title = {Alternative Method for Predictive Functional Control to Handle an Integrating Process},
author = {Abdullah, M.; Rossiter, J.A.},
booktitle = {Control 2018 - 12th UKACC International Conference on Control},
year = {2018},
institution = {University of Sheffield, UK; International Islamic University Malaysia, Malaysia},
abstract = {This work proposes an improved method for Predictive Functional Control (PFC) to handle an integrating process. Instead of assuming a constant future input, the dynamic is shaped with a first-order Laguerre polynomial so that it converges to the expected steady state value. This modification provides simpler coding and tuning compared to the conventional method in the literature. Simulation results show that the proposed controller improves the consistency of the open-loop prediction of an integrating process and thus improves closed-loop performance and constraint handling properties. The practicality of this algorithm is also validated on laboratory hardware. },
keywords = {Predictive Control, PFC, Laguerre Function, Constraints, Integrating Process, Transparent Control, Servo System},
language = {English},
publisher = {IEEE}
}

This work proposes an improved method for Predictive Functional Control (PFC) to handle an integrating process. Instead of assuming a constant future input, the dynamic is shaped with a first-order Laguerre polynomial so that it converges to the expected steady state value. This modification provides simpler coding and tuning compared to the conventional method in the literature. Simulation results show that the proposed controller improves the consistency of the open-loop prediction of an integrating process and thus improves closed-loop performance and constraint handling properties. The practicality of this algorithm is also validated on laboratory
hardware.

@article{alemaryeen_2018,
title = {Antenna Effects on Respiratory Rate Measurement using a UWB Radar System},
author = {Alemaryeen, A.; Noghanian, S.; Fazel-Rezai, R.},
journal = {IEEE Journal of Electromagnetics, RF and Microwaves in Medicine and Biology},
year = {2018},
institution = {Electrical Engineering, University of North Dakota, USA},
abstract = {State-of-the-art advances in the field of radar technology have made it possible to design non-invasive sensing devices of vital signs. This paper presents the effects of antenna characteristics on Ultra Wide Band (UWB) radar-based respiratory rate measurement system for tele-health-monitoring applications. The performance of three types of antenna for a UWB radar respiratory rate measurement system was studied in this work. In this context, the proposed system was comprehensively evaluated using two experimental sets. First, a mechanical setup was used to provide a series of controlled frequency and distance motions for measurement test. The error analysis for various parameters associated with pulmonary activities such as breathing frequency and chest displacement was performed. Results indicated that the proposed sensing system used effectively as a respiratory rate measurement is less affected and shows less error when an antenna with directive radiation pattern, low cross-polarization and stable phase center was used. Due to its good radiation characteristics and small form-factor this antenna was selected to study the respiratory rates of ten test subjects. The results were compared with a standard respiratory-rate measurement using respiration belt transducer. The measurement results using the proposed and the standard systems showed excellent agreement. The mean error value of the respiratory rate measurements was 0.03 Hz with a statistical standard deviation of 0.03 Hz. },
issn = {2469-7249},
keywords = {Antennas, respiratory rate detection, remote sensing, ultra-wide band (UWB) radar},
language = {English},
publisher = {IEEE}
}

State-of-the-art advances in the field of radar technology have made it possible to design non-invasive sensing devices of vital signs. This paper presents the effects of antenna characteristics on Ultra Wide Band (UWB) radar-based respiratory rate measurement system for tele-health-monitoring applications. The performance of three types of antenna for a UWB radar respiratory rate measurement system was studied in this work. In this context, the proposed system was comprehensively evaluated using two experimental sets. First, a mechanical setup was used to provide a series of controlled frequency and distance motions for measurement test. The error analysis for various parameters associated with pulmonary activities such as breathing frequency and chest displacement was performed. Results indicated that the proposed sensing system used effectively as a respiratory rate measurement is less affected and shows less error when an antenna with directive radiation pattern, low cross-polarization and stable phase center was used. Due to its good radiation characteristics and small form-factor this antenna was selected to study the respiratory rates of ten test subjects. The results were compared with a standard respiratory-rate measurement using respiration belt transducer. The measurement results using the proposed and the standard systems showed excellent agreement. The mean error value of the respiratory rate measurements was 0.03 Hz with a statistical standard deviation of 0.03 Hz.

@conference{sun2_2018,
title = {Anti-Disturbance Study of Position Servo System Based on Disturbance Observer},
author = {Sun, J.; Wang, C.; Xin, R.},
booktitle = {3rd IFAC Conference on Advances in Proportional-Integral-Derivative Control PID 2018},
year = {2018},
institution = {Changchun University of Science and Technology, China},
abstract = {In this paper, the mechanism and method of using disturbance observer (DOB) to eliminate the disturbance are studied and applied to the control of position servo system. The DOB consists of an inverse model of the controlled object and a filter, and suppresses the external disturbance acting on the servo system. Based on the traditional proportional integral derivative (PID) controller, simulations on MATLAB/Simulink and tests on Quanser semi-physical experiment platform are performed for the PID controller with DOB and without DOB. Simulation and experimental results show that the introduction of DOB can effectively suppress the external disturbance and improve the dynamic response performance and stability of the servo system. },
keywords = {Proportional Integral Derivative Control, Disturbance Observer, Anti-Disturbance Position Servo System, Quanser Experiment Device.},
language = {English},
series = {IFAC-PapersOnLine},
publisher = {Elsevier Ltd.}
}

In this paper, the mechanism and method of using disturbance observer (DOB) to eliminate the disturbance are studied and applied to the control of position servo system. The DOB consists of an inverse model of the controlled object and a filter, and suppresses the external disturbance acting on the servo system. Based on the traditional proportional integral derivative (PID) controller, simulations on MATLAB/Simulink and tests on Quanser semi-physical experiment platform are performed for the PID controller with DOB and without DOB. Simulation and experimental results show that the introduction of DOB can effectively suppress the external disturbance and improve the dynamic response performance and stability of the servo system.

@article{yi_2018,
title = {Control Design for Articulating Turbine Rotor Blades for High-Efficiency Turbine Operation},
author = {Yi, S.; Murugan, M.; Ghoshal, A.},
year = {2018},
institution = {North Carolina A&T State University, USA; CCDC Army Research Laboratory, USA},
abstract = {Conventional gas turbine engines are designed to operate at nearly fixed operation conditions including speed and blade geometries. If the operating conditions change, the flow incidence angles may not be optimum with the blade geometries and thus result in reduced performance. Active control of the pitch angles of compressor and turbine blades can improve performance by maintaining flow incidence angles within the optimum range for given blade geometries for varying operating conditions. Articulating the angles of turbine or compressor blade using smart material-based actuators such as Shape Memory Alloy (SMA) has been investigated under this effort. In using SMA actuators, output position tracking control plays an important role in the control process, and the control objective is to make the output position robustly follow the desired reference. A nonlinear control theory was adopted to address the hysteresis and nonlinearity. According to the system dynamics characteristics, control laws have been designed to achieve the output position tracking control and maintain the stability of the closed-loop system. },
keywords = {adaptive turbomachinery blade, Shape Memory Alloy actuator, adaptive control, nonlinear control, active incident tolerant blade},
language = {English}
}

Conventional gas turbine engines are designed to operate at nearly fixed operation conditions including speed and blade geometries. If the operating conditions change, the flow incidence angles may not be optimum with the blade geometries and thus result in reduced performance. Active control of the pitch angles of compressor and turbine blades can improve performance by maintaining flow incidence angles within the optimum range for given blade geometries for varying operating conditions. Articulating the angles of turbine or compressor blade using smart material-based actuators such as Shape Memory Alloy (SMA) has been investigated under this effort. In using SMA actuators, output position tracking control plays an important role in the control process, and the control objective is to make the output position robustly follow the desired reference. A nonlinear control theory was adopted to address the hysteresis and nonlinearity. According to the system dynamics characteristics, control laws have been designed to achieve the output position tracking control and maintain the stability of the closed-loop system.

@conference{sun_2018,
title = {Design of fractional order proportional differentiation controller for second order position servo system},
author = {Sun, J.;Wang, C.; Xin, R.},
booktitle = {2018 Chinese Control And Decision Conference (CCDC)},
year = {2018},
institution = {Changchun University of Science and Technology, China},
abstract = {This paper considers a tuning method of factional order proportional derivative (FOPD) controller based on vector model for the second order position servo system. This method is designed to improve the closed-loop system's dynamic performance and robustness. Simulations in MATLAB/Simulink and tests on Quanser semi-physical experiment platform are performed after the design of controller for position servo system. The simulation and experimental results reveal that the designed factional order proportional derivative (FOPD) controller works more effectively than integer order proportional integral derivative (IOPID) controller, with the improved performance of faster response speed and stronger anti-jamming capability. },
issn = {1948-9447},
keywords = {Fractional order proportional differentiation controller, Vector model, Position servo system, Quanser experiment device, Robustness},
language = {English},
publisher = {IEEE}
}

This paper considers a tuning method of factional order proportional derivative (FOPD) controller based on vector model for the second order position servo system. This method is designed to improve the closed-loop system's dynamic performance and robustness. Simulations in MATLAB/Simulink and tests on Quanser semi-physical experiment platform are performed after the design of controller for position servo system. The simulation and experimental results reveal that the designed factional order proportional derivative (FOPD) controller works more effectively than integer order proportional integral derivative (IOPID) controller, with the improved performance of faster response speed and stronger anti-jamming capability.

@article{subramanian_2018,
title = {Discrete-time setpoint-triggered reset integrator design with guaranteed performance and stability},
author = {Subramanian, R.G.; Elumalai, V.K.},
journal = {ISA Transactions},
year = {2018},
institution = {Eindhoven University of Technology, The Netherlands; VIT University, India},
abstract = {According to Bode's gain-phase relationship, in linear time-invariant controllers, introducing an integral action to eliminate the steady-state error has an adverse effect of increased phase delay and overshoot, leading to performance deterioration. Moreover, increasing the bandwidth of the closed-loop system to enhance the low-frequency disturbance rejection invariably amplifies the sensitivity to high-frequency disturbances. Hence, the performance of the linear controllers is always limited due to these fundamental frequency- and time-domain limitations. Motivated by the desire to address the fundamental limitations of linear controllers and improve the time-varying closed-loop performance, we put forward a novel setpoint-triggered reset integrator strategy that varies the integrator cut-off frequency based on the setpoint information. Particularly, to tackle the time-varying disturbances and setpoint profiles, the proposed controller consists of a nominal linear controller and a variable-gain reset integrator. We show the global asymptotic stability of the proposed methodology using positive-real lemma along with the LaSalle's invariance principle and experimentally validate using measured frequency response function. Moreover, the efficacy of the proposed technique compared to that of the linear controller is experimentally demonstrated on a benchmark rotary servo system. Experimental results assessed using the tracking error and cumulative power spectral density substantiate that the proposed control strategy can not only improve the low-frequency disturbance rejection but also augment the high-frequency trajectory tracking performance. },
keywords = {Reset control, Stability, Hybrid control, Servo performance},
language = {English},
publisher = {Elsevier Ltd.}
}

According to Bode's gain-phase relationship, in linear time-invariant controllers, introducing an integral action to eliminate the steady-state error has an adverse effect of increased phase delay and overshoot, leading to performance deterioration. Moreover, increasing the bandwidth of the closed-loop system to enhance the low-frequency disturbance rejection invariably amplifies the sensitivity to high-frequency disturbances. Hence, the performance of the linear controllers is always limited due to these fundamental frequency- and time-domain limitations. Motivated by the desire to address the fundamental limitations of linear controllers and improve the time-varying closed-loop performance, we put forward a novel setpoint-triggered reset integrator strategy that varies the integrator cut-off frequency based on the setpoint information. Particularly, to tackle the time-varying disturbances and setpoint profiles, the proposed controller consists of a nominal linear controller and a variable-gain reset integrator. We show the global asymptotic stability of the proposed methodology using positive-real lemma along with the LaSalle's invariance principle and experimentally validate using measured frequency response function. Moreover, the efficacy of the proposed technique compared to that of the linear controller is experimentally demonstrated on a benchmark rotary servo system. Experimental results assessed using the tracking error and cumulative power spectral density substantiate that the proposed control strategy can not only improve the low-frequency disturbance rejection but also augment the high-frequency trajectory tracking performance.

@conference{chen2_2018,
title = {Distributed Fixed-Time Control of Multi-agent Systems with Input Shaping},
author = {Chen, T.; Shan, J.},
booktitle = {IEEE International Conference on Information and Automation (ICIA 2018)},
year = {2018},
institution = {York University, Canada},
abstract = {This paper presents novel fixed-time control for second-order multi-agent systems based on input shaping technique under undirected and directed graphs. To satisfy the requirement of multi-agent systems, the input shaping technique is extended to solve the control of an oscillation system with non-zero initial position firstly. The distributed fixed-time controllers are proposed based on the shaped command to achieve rest-to-rest maneuver of multi-agent systems under connected undirected graph where there is at least one node linked to the leader. For the directed graph with a globally reachable leader and no circle, distributed fixed-time controllers are designed by placing input shapers in all communication edges in the graph. Finally, experimental results are presented to verify the effectiveness of the proposed controllers. },
keywords = {Fixed-time; multi-agent systems; input shaping},
language = {English}
}

This paper presents novel fixed-time control for second-order multi-agent systems based on input shaping technique under undirected and directed graphs. To satisfy the requirement of multi-agent systems, the input shaping technique is extended to solve the control of an oscillation system with non-zero initial position firstly. The distributed fixed-time controllers are proposed based on the shaped command to achieve rest-to-rest maneuver of multi-agent systems under connected undirected graph where there is at least one node linked to the leader. For the directed graph with a globally reachable leader and no circle, distributed fixed-time controllers are designed by placing input shapers in all communication edges in the graph. Finally, experimental results are presented to verify the effectiveness of the proposed controllers.

@article{chen_2018,
title = {Fixed-time consensus control of multi-agent systems using input shaping},
author = {Chen, T.; Shan, J.},
journal = { IEEE Transactions on Industrial Electronics},
year = {2018},
institution = {York University, Canada},
abstract = {This paper presents the development of novel fixed-time consensus controllers of simple form for the second-order multi-agent systems based on input shaping under undirected communication graph. To satisfy the requirement of multi-agent systems, the input shaping technique is extended to solve the control of an oscillation system with non-zero initial position firstly. Then, three cases are considered under the connected undirected graph. Theoretical analyses are presented to solve the exact convergence time based on the responses of the closed-loop multi-agent systems. Finally, numerical simulations and experiments are conducted to verify the effectiveness of the proposed controllers. },
issn = {0278-0046 },
keywords = {Fixed-time consensus, input shaping, multi-agent systems, double-integrator dynamics, undirected topology},
language = {English},
publisher = {IEEE}
}

This paper presents the development of novel fixed-time consensus controllers of simple form for the second-order multi-agent systems based on input shaping under undirected communication graph. To satisfy the requirement of multi-agent systems, the input shaping technique is extended to solve the control of an oscillation system with non-zero initial position firstly. Then, three cases are considered under the connected undirected graph. Theoretical analyses are presented to solve the exact convergence time based on the responses of the closed-loop multi-agent systems. Finally, numerical simulations and experiments are conducted to verify the effectiveness of the proposed controllers.

@inbook{frank_2018,
title = {Mobile Cyber-Physical Labs: Integration of Mobile Devices with System},
author = {Frank J.A.; Brill A.; Kapila V.},
booktitle = {Cyber-Physical Laboratories in Engineering and Science Education},
year = {2018},
institution = {NYU Tandon School of Engineering, USA},
abstract = {Recent years have witnessed the adoption of mobile devices to deliver valuable interactive learning experiences to students. Although prior efforts have led to the development of mobile applications that enhance access to virtual and remote laboratories, research has not yet explored the comprehensive integration of mobile technologies into traditional laboratory activities. In this chapter, we present the development of mobile cyber-physical laboratories (MCPLs) in which hardware and software of mobile devices are leveraged in measurement, control, monitoring, and interaction with physical test-beds in the laboratory. Two separate approaches for realizing cost-effective and portable educational test-beds are proposed that utilize the sensing, storage, computation, and communication (SSCC) capabilities of mobile devices to facilitate inquiry-based educational experiences. In the first approach, smartphones are mounted directly to test-beds to allow inertial- and/or vision-based measurement and control of the test-bed. In the second approach, tablets are held such that their rear-facing cameras allow vision-based measurement and control of the test-bed. By developing mobile applications that incorporate interactive plots and augmented reality visualizations, unique and engaging learning experiences are provided from learners’ personal mobile devices. The implementation and evaluation of each approach is discussed with a motor test-bed used to teach concepts of dynamic systems and control. Results of investigations indicate that by intimately linking concrete physical and cyber representations of phenomena through interactive, visually engaging interfaces, the MCPLs allow learners to make connections necessary for deep conceptual understanding and to engage in activities that hone their design skills. },
keywords = {Augmented reality, Dynamic systems, Mobile learning, Mixed-reality learning, Virtual reality },
language = {English},
publisher = {Springer, Cham},
isbn = {978-3-319-76935-6},
pages = {403-434},
chapter = {16}
}

Recent years have witnessed the adoption of mobile devices to deliver valuable interactive learning experiences to students. Although prior efforts have led to the development of mobile applications that enhance access to virtual and remote laboratories, research has not yet explored the comprehensive integration of mobile technologies into traditional laboratory activities. In this chapter, we present the development of mobile cyber-physical laboratories (MCPLs) in which hardware and software of mobile devices are leveraged in measurement, control, monitoring, and interaction with physical test-beds in the laboratory. Two separate approaches for realizing cost-effective and portable educational test-beds are proposed that utilize the sensing, storage, computation, and communication (SSCC) capabilities of mobile devices to facilitate inquiry-based educational experiences. In the first approach, smartphones are mounted directly to test-beds to allow inertial- and/or vision-based measurement and control of the test-bed. In the second approach, tablets are held such that their rear-facing cameras allow vision-based measurement and control of the test-bed. By developing mobile applications that incorporate interactive plots and augmented reality visualizations, unique and engaging learning experiences are provided from learners’ personal mobile devices. The implementation and evaluation of each approach is discussed with a motor test-bed used to teach concepts of dynamic systems and control. Results of investigations indicate that by intimately linking concrete physical and cyber representations of phenomena through interactive, visually engaging interfaces, the MCPLs allow learners to make connections necessary for deep conceptual understanding and to engage in activities that hone their design skills.

@conference{ozer_2018,
title = {Optimization-based PV/PI Design for a DC-Motor System with Delayed Feedback},
author = {Ozer, S.M.; Yildiz, S.; Iftar, A.},
booktitle = {26th Mediterranean Conference on Control and Automation 2018},
year = {2018},
institution = {Department of Electrical and Electronics Engineering, Anadolu University, Turkey},
abstract = {Proportional velocity (PV) and proportional integral (PI) controllers are designed to regulate the angular position and angular velocity, respectively, of a DC motor system with a pointwise time-delay in the feedback loop. Because of the time-delay, the system is described by delay-differential equations which have infinitely many modes that can not be assigned by using classical pole placement methods. The proposed method is based on minimizing the real part of the rightmost closed-loop mode, i.e., spectral abscissa, as a function of the controller parameters. The effectiveness of the method is illustrated by simulations and real-time experiments. },
issn = {2473-3504 },
language = {English},
publisher = {IEEE},
isbn = {978-1-5386-7499-4}
}

Proportional velocity (PV) and proportional integral (PI) controllers are designed to regulate the angular position and angular velocity, respectively, of a DC motor system with a pointwise time-delay in the feedback loop. Because of the time-delay, the system is described by delay-differential equations which have infinitely many modes that can not be assigned by using classical pole placement methods. The proposed method is based on minimizing the real part of the rightmost closed-loop mode, i.e., spectral abscissa, as a function of the controller parameters. The effectiveness of the method is illustrated by simulations and real-time experiments.

@conference{ozer2_2018,
title = {Performance Analysis of a DC-Motor Control System with Time-Delay: Smith Predictor vs Optimization-based Controller Design},
author = {Ozer, S.M.; Yildiz, S.; Iftar, A.},
booktitle = {6th International Conference on Control Engineering & Information Technology},
year = {2018},
institution = {Anadolu University, Yurkey},
abstract = {Smith predictor-based and optimization-based controller design for a DC-motor control system with a time-delay in the feedback loop is considered. It is shown that, compared to the Smith predictor-based controller, the optimization-based controller can preserve stability against larger variations in the system parameters and the time-delay. Furthermore, by simulations and actual experiments, it is verified that the optimization-based controller outperforms the Smith predictor-based controller when the system parameters and, especially, the time-delay varies. },
keywords = {Time-delay systems, stabilization, robustness, Smith predictor, optimization, DC-motor control},
language = {English}
}

Smith predictor-based and optimization-based controller design for a DC-motor control system with a time-delay in the feedback loop is considered. It is shown that, compared to the Smith predictor-based controller, the optimization-based controller can preserve stability against larger variations in the system parameters and the time-delay. Furthermore, by simulations and actual experiments, it is verified that the optimization-based controller outperforms the Smith predictor-based controller when the system parameters and, especially, the time-delay varies.

@article{chabria_2018,
title = {Targeted synchronization in an externally driven population of mechanical oscillators},
author = {Chhabria, S.; Blaha, K.A.; Della Rossa, F.; Sorrentino, F.},
journal = {Chaos},
year = {2018},
volume = {28},
number = {11},
institution = {University of New Mexico, USA},
abstract = {We experimentally investigate the synchronization of driven metronomes using a servo motor to impose external control. We show that a driven metronome will only synchronize in a narrow range near its own frequency; when we introduce coupling between metronomes, we can widen the range of frequencies over which a metronome will synchronize to the external input. Using these features, we design a signal to synchronize a population of dissimilar metronomes; separately we design a signal to selectively synchronize a subpopulation of metronomes within a heterogeneous population. },
language = {English},
publisher = {AIP Publishing}
}

We experimentally investigate the synchronization of driven metronomes using a servo motor to impose external control. We show that a driven metronome will only synchronize in a narrow range near its own frequency; when we introduce coupling between metronomes, we can widen the range of frequencies over which a metronome will synchronize to the external input. Using these features, we design a signal to synchronize a population of dissimilar metronomes; separately we design a signal to selectively synchronize a subpopulation of metronomes within a heterogeneous population.

@conference{abdullahi_2017,
title = {Design and Simulation of a PID Controller for Motion Control Systems},
author = {Abdullahi Z.H., Danzomo B.A., Abdullahi Z.S.},
booktitle = {3rd International Conference on Science, Technology and Interdisciplinary Research 2017},
year = {2017},
volume = {344},
institution = {Hussaini Adamu Federal Polytechnic, Nigeria},
abstract = {Motion control system plays important role in many industrial applications among which are in robot system, missile launching, positioning systems etc. However, the performance requirement for these applications in terms of high accuracy, high speed, insignificant or no overshoot and robustness have generated continuous challenges in the field of motion control system design and implementation. To compensate this challenge, a PID controller was design using mathematical model of a DC motor based on classical root-locus approach. The reason for adopting root locus design is to remodel the closed-loop response by putting the closed-loop poles of the system at desired points. Adding poles and zeros to the initial open-loop transfer function through the controller provide a way to transform the root locus in order to place the closed-loop poles at the required points. This process can also be used for discrete-time models. The Advantages of root locus over other methods is that, it gives the better way of pinpointing the parameters and can easily predict the fulfilment of the whole system. The controller performance was simulated using MATLAB code and a reasonable degree of accuracy was obtained. Implementation of the proposed model was conducted using Simulink and the result obtained shows that the PID controller met the transient performance specifications with both settling time and overshoot less than 0.1s and 5% respectively. In terms of steady state error, the PID controller gave good response for both step input and ramp. },
language = {English}
}

Motion control system plays important role in many industrial applications among which are in robot system, missile launching, positioning systems etc. However, the
performance requirement for these applications in terms of high accuracy, high speed, insignificant or no overshoot and robustness have generated continuous challenges in the field of motion control system design and implementation. To compensate this challenge, a PID controller was design using mathematical model of a DC motor based on classical root-locus approach. The reason for adopting root locus design is to remodel the closed-loop response by putting the closed-loop poles of the system at desired points. Adding poles and zeros to the initial open-loop transfer function through the controller provide a way to transform the root locus in order to place the closed-loop poles at the required points. This process can also be used for discrete-time models. The Advantages of root locus over other methods is that, it gives the better way of pinpointing the parameters and can easily predict the fulfilment of the whole system. The controller performance was simulated using MATLAB code and a reasonable degree of accuracy was obtained. Implementation of the proposed model was conducted using Simulink and the result obtained shows that the PID controller met the transient performance specifications with both settling time and overshoot less than 0.1s and 5% respectively. In terms of steady state error, the PID controller gave good response for both step input and ramp.

@article{yang_2017,
title = {FPAA-Based Control of Bilateral Teleoperation Systems for Enhanced User Task Performance},
author = {Yang, T.; Hu, J.; Geng, W.; Fu, Y.; Tavakoli, M. },
journal = {Presence},
year = {2017},
month = {05},
volume = {26},
number = {2},
institution = {Xuzhou Medical University, China; Harbin Institute of Technology, China; University of Alberta, AB, Canada},
abstract = {In a bilateral teleoperation system, discrete-time implementation of the controller can cause performance degradation. This is due to a well-known stability-imposed upper bound on the product of the discrete-time controller's gain and the sampling period. In this article, for a bilateral teleoperation system, a continuous-time controller based on a Field Programmable Analog Array (FPAA) is deployed and compared in terms of performance with its discrete-time counterpart. Experimental results show that, unlike the discrete-time controller, the FPAA-based controller helps the human user complete teleoperation tasks that require high controller gains such as when a large impedance needs to be displayed against the user's hand. Also, an experimental object stiffness discrimination study shows that large sampling periods, necessitating low control gains for maintaining stability, lead to unacceptable task performance by the user; however, the users show an improved ability to discriminate the various objects if the teleoperation controller is implemented using an FPAA. },
issn = {1054-7460},
language = {English},
publisher = {IEEE}
}

In a bilateral teleoperation system, discrete-time implementation of the controller can cause performance degradation. This is due to a well-known stability-imposed upper bound on the product of the discrete-time controller's gain and the sampling period. In this article, for a bilateral teleoperation system, a continuous-time controller based on a Field Programmable Analog Array (FPAA) is deployed and compared in terms of performance with its discrete-time counterpart. Experimental results show that, unlike the discrete-time controller, the FPAA-based controller helps the human user complete teleoperation tasks that require high controller gains such as when a large impedance needs to be displayed against the user's hand. Also, an experimental object stiffness discrimination study shows that large sampling periods, necessitating low control gains for maintaining stability, lead to unacceptable task performance by the user; however, the users show an improved ability to discriminate the various objects if the teleoperation controller is implemented using an FPAA.

@article{priya_2017,
title = {Frequency response method to derive transfer function of servo motor using Quanser servo plant module and dSPACE software},
author = {Priya, J.; Vidhya, M.; Rambrintha, R.; Venkatesh, P.},
journal = {International Research Journal of Engineering and Technology},
year = {2017},
volume = {4},
number = {2},
institution = {Bannari Amman Institute of Technology, India; Thiagarajar College of Engineering, India},
abstract = {A Quanser servo plant module and dSPACE software with the DS1104 R&D controller board is used in the experiment to derive transfer function of servo motor that describes the load shaft position with respect to the motor input voltage using frequency response method and to develop a feedback system that controls the position of the rotary servo load shaft. The objective of the paper is to carry out real time experiment using state of art hardware dSPACE DS1104 R&D controller board in a laboratory education point of view. },
issn = {2395-0072},
keywords = {Quanser servo plant (SRV02), Frequency response method (FM), dSPACE R&D controller board (DS1104), Proportional Velocity (PV), Proportional Integral Velocity (PIV)},
language = {English},
pages = {1136-1142}
}

A Quanser servo plant module and dSPACE software with the DS1104 R&D controller board is used in the experiment to derive transfer function of servo motor that describes the load shaft position with respect to the motor input voltage using frequency response method and to develop a feedback system that controls the position of the rotary servo load shaft. The objective of the paper is to carry out real time experiment using state of art hardware dSPACE DS1104 R&D controller board in a laboratory education point of view.

@article{frank_2017,
title = {Mixed-reality learning environments – Integrating mobile interfaces with laboratory test-beds},
author = {Frank, J.A.; Kapila, V.},
journal = {Computers & Education},
year = {2017},
month = {7},
volume = {110},
institution = {NYU Tandon School of Engineering, Mechanical and Aerospace Engineering Department, NY, USA},
abstract = {Even as mobile devices have become increasingly powerful and popular among learners and instructors alike, research involving their comprehensive integration into educational laboratory activities remains largely unexplored. This paper discusses efforts to integrate vision-based measurement and control, augmented reality (AR), and multi-touch interaction on mobile devices in the development of Mixed-Reality Learning Environments (MRLE) that enhance interactions with laboratory test-beds for science and engineering education. A learner points her device at a laboratory test-bed fitted with visual markers while a mobile application supplies a live view of the experiment augmented with interactive media that aid in the visualization of concepts and promote learner engagement. As the learner manipulates the augmented media, her gestures are mapped to commands that alter the behavior of the test-bed on the fly. Running in the background of the mobile application are algorithms performing vision-based estimation and wireless control of the test-bed. In this way, the sensing, storage, computation, and communication (SSCC) capabilities of mobile devices are leveraged to relieve the need for laboratory-grade equipment, improving the cost-effectiveness and portability of platforms to conduct hands-on laboratories. We hypothesize that students using the MRLE platform demonstrate improvement in their knowledge of dynamic systems and control concepts and have generally favorable experiences using the platform. To validate the hypotheses concerning the educational effectiveness and user experience of the MRLEs, an evaluation was conducted with two classes of undergraduate students using an illustrative platform incorporating a tablet computer and motor test-bed to teach concepts of dynamic systems and control. Results of the evaluation validate the hypotheses. The benefits and drawbacks of the MRLEs observed throughout the study are discussed with respect to the traditional hands-on, virtual, and remote laboratory formats. },
keywords = {Applications in subject areas; Architectures for educational technology system; Improving classroom teaching; Interactive learning environments; Virtual reality},
language = {English},
publisher = {Elsevier Ltd.},
pages = {88-104}
}

Even as mobile devices have become increasingly powerful and popular among learners and instructors alike, research involving their comprehensive integration into educational laboratory activities remains largely unexplored. This paper discusses efforts to integrate vision-based measurement and control, augmented reality (AR), and multi-touch interaction on mobile devices in the development of Mixed-Reality Learning Environments (MRLE) that enhance interactions with laboratory test-beds for science and engineering education. A learner points her device at a laboratory test-bed fitted with visual markers while a mobile application supplies a live view of the experiment augmented with interactive media that aid in the visualization of concepts and promote learner engagement. As the learner manipulates the augmented media, her gestures are mapped to commands that alter the behavior of the test-bed on the fly. Running in the background of the mobile application are algorithms performing vision-based estimation and wireless control of the test-bed. In this way, the sensing, storage, computation, and communication (SSCC) capabilities of mobile devices are leveraged to relieve the need for laboratory-grade equipment, improving the cost-effectiveness and portability of platforms to conduct hands-on laboratories. We hypothesize that students using the MRLE platform demonstrate improvement in their knowledge of dynamic systems and control concepts and have generally favorable experiences using the platform. To validate the hypotheses concerning the educational effectiveness and user experience of the MRLEs, an evaluation was conducted with two classes of undergraduate students using an illustrative platform incorporating a tablet computer and motor test-bed to teach concepts of dynamic systems and control. Results of the evaluation validate the hypotheses. The benefits and drawbacks of the MRLEs observed throughout the study are discussed with respect to the traditional hands-on, virtual, and remote laboratory formats.

@conference{alemaryeen_2017,
title = {Respiratory rate measurements via Doppler radar for health monitoring applications},
author = {Alemaryeen, A.; Noghanian, S.; Fazel-Rezai, R.},
booktitle = {2017 39th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC)},
year = {2017},
institution = {Department of Electrical Engineering, University of North Dakota, USA},
abstract = {This paper presents experimental results for measuring respiratory rate using non-contact and low power system for health-monitoring applications. The system is based on a Doppler effect. A mechanical setup with controllable movement frequency and displacement was built to mimic the human chest movements while breathing. A Doppler radar system was used to measure the frequency of the proposed system. Three different antennas were used to study the effect of antenna radiation pattern, gain, and cross-polarization on the accuracy of the measurements. An error analysis was conducted for different frequencies and displacements. Results demonstrated that the antenna of a moderate directivity and gain values, and of the least cross-polarization components has higher accuracy compared to other proposed antennas. It can be concluded that with a good selection of antenna it is possible to measure respiratory rate with a small error using the proposed radar system. },
keywords = {Antenna measurements, Radar antennas, Frequency measurement, Directive antennas, Doppler radar},
language = {English},
publisher = {IEEE}
}

This paper presents experimental results for measuring respiratory rate using non-contact and low power system for health-monitoring applications. The system is based on a Doppler effect. A mechanical setup with controllable movement frequency and displacement was built to mimic the human chest movements while breathing. A Doppler radar system was used to measure the frequency of the proposed system. Three different antennas were used to study the effect of antenna radiation pattern, gain, and cross-polarization on the accuracy of the measurements. An error analysis was conducted for different frequencies and displacements. Results demonstrated that the antenna of a moderate directivity and gain values, and of the least cross-polarization components has higher accuracy compared to other proposed antennas. It can be concluded that with a good selection of antenna it is possible to measure respiratory rate with a small error using the proposed radar system.

@article{ren_2016,
title = {Asymptotic Reference Tracking and Disturbance Rejection of UDE-Based Robust Control},
author = {Ren, B.; Zhong, Q.-C.; Dai, J.},
journal = {IEEE Transactions on Industrial Electronics},
year = {2016},
institution = {Illinois Institute of Technology, Chicago, USA},
abstract = {The uncertainty and disturbance estimation (UDE)-based robust control strategy is able to achieve good robust performance by estimating and compensating the uncertainty and disturbance in a system with a filter having the appropriate frequency characteristics. However, how to systematically design the filter and the reference system in a UDE-based control system to achieve asymptotic reference tracking and disturbance rejection is still missing in the literature. In this paper, this is solved by applying the well-known internal model principle. The conditions to guarantee the closed-loop system stability and to achieve asymptotic disturbance rejection and reference tracking are derived. Experimental results on a servo system are presented as an example to demonstrate its excellent performance, which can actually reach the hardware resolution limit, with comparisons to the disturbance observer based control and the active disturbance rejection control. },
issn = {0278-0046},
keywords = {Robust control, uncertainty and disturbance estimator (UDE), internal model principle, asymptotic tracking, asymptotic disturbance rejection},
language = {English},
publisher = {IEEE}
}

The uncertainty and disturbance estimation (UDE)-based robust control strategy is able to achieve good robust performance by estimating and compensating the uncertainty and disturbance in a system with a filter having the appropriate frequency characteristics. However, how to systematically design the filter and the reference system in a UDE-based control system to achieve asymptotic reference tracking and disturbance rejection is still missing in the literature. In this paper, this is solved by applying the well-known internal model principle. The conditions to guarantee the closed-loop system stability and to achieve asymptotic disturbance rejection and reference tracking are derived. Experimental results on a servo system are presented as an example to demonstrate its excellent performance, which can actually reach the hardware resolution limit, with comparisons to the disturbance observer based control and the active disturbance rejection control.

@article{bucevac_2016,
title = {Discrete-time chattering free exponentially stabilizing sliding mode scalar control via LyapunovÍs method},
author = {Bucevac, Z.M.; Jovanovic, R.Z.},
journal = {International Journal of Control, Automation and Systems},
year = {2016},
volume = {14},
number = {3},
institution = {University of Belgrade, Serbia},
abstract = {Linear time-invariant discrete-time plant, with no restrictions on the form of the state equation and with scalar control, is considered. The exponentially stabilizing state feedback control algorithm is developed by LyapunovÍs second method leading to the variable structure system with chattering free sliding modes. Essentially, the control algorithm drives the system from an arbitrary initial state to a prescribed so-called sliding subspace S, in finite time and with prescribed velocity estimate. Inside the sliding subspace S, the system is switched to the sliding mode regime and stays in it forever. The proposed algorithm is tested on the real system in practice, direct current (DC) servo motor, and simulation and experimental results are given. Also, it is compared with another already known algorithm from literature. },
issn = {1598-6446},
keywords = {Chattering free sliding mode, discrete-time systems, exponential stability, LyapunovÍs method, variable structure},
language = {English},
publisher = {Institute of Control, Robotics and Systems and The Korean Institute of Electrical Engineers},
pages = {698-705}
}

Linear time-invariant discrete-time plant, with no restrictions on the form of the state equation and with scalar control, is considered. The exponentially stabilizing state feedback control algorithm is developed by LyapunovÍs second method leading to the variable structure system with chattering free sliding modes. Essentially, the control algorithm drives the system from an arbitrary initial state to a prescribed so-called sliding subspace S, in finite time and with prescribed velocity estimate. Inside the sliding subspace S, the system is switched to the sliding mode regime and stays in it forever. The proposed algorithm is tested on the real system in practice, direct current (DC) servo motor, and simulation and experimental results are given. Also, it is compared with another already known algorithm from literature.

@article{huang_2016,
title = {Fractional Order Modeling of Human Operator Behavior with Second Order Controlled Plant and Experiment Research},
author = {Huang, Jiacai; Chen, Yangquan; Li, Haibin; Shi, Xinxin},
journal = {IEEE/CAA Journal of Automatica},
year = {2016},
abstract = {Modeling human operatorÍs dynamic plays a very important role in the manual closed-loop control system, and it is an active research area for several decades. Based on the characteristics of human brain and behaviour, a new kind of fractional order mathematical model for human operator in SISO systems is proposed. Compared with the traditional models based on the commonly used quasi-linear transfer function method or the optimal control theory method, the proposed fractional order model has simple structure with only few parameters, and each parameter has explicit physical meanings. The actual data and experiment results with the second-order controlled element illustrate the effectiveness of the proposed method. },
keywords = {Fractional order modeling, fractional calculus, human operator, human in the loop, second order controlled plant},
language = {English}
}

Modeling human operatorÍs dynamic plays a very important role in the manual closed-loop control system, and it is an active research area for several decades. Based on the characteristics of human brain and behaviour, a new kind of fractional order mathematical model for human operator in SISO systems is proposed. Compared with the traditional models based on the commonly used quasi-linear transfer function method or the optimal control theory method, the proposed fractional order model has simple structure with only few parameters, and each parameter has explicit physical meanings. The actual data and experiment results with the second-order controlled element illustrate the effectiveness of the proposed method.

@article{sayem_2016,
title = {Model Free ESO-based Repetitive Control for Rejecting Periodic and Aperiodic Disturbances},
author = {Sayem, A.H.M.; Cao, Z.; Man, Z.},
journal = {IEEE Transactions on Industrial Electronics},
year = {2016},
institution = {Faculty of Science, Engineering and Technology, Swinburne University of Technology, Melbourne, Australia},
abstract = {This paper presents an extended state observer (ESO) based repetitive controller (RC) to compensate periodic signals, aperiodic disturbances and uncertainties of the plant with relative degree equal or greater than zero. Since linear ESO has only two tuning parameters, the proposed controller provides a simple and user friendly solution to complex engineering problems in practice. Moreover, due to the model free approach of ESO-based control, it can be applied to a wide variety of plants. The design procedures are proposed to ensure a stable system. Various types of disturbances are used in simulations and experiments which show that the ESO-based RC can not only reject periodic and aperiodic disturbances but also handle the plant parameter uncertainty. The comparison studies demonstrate that the ESO-based RC has superb performance. },
keywords = {Repetitive Control, State Observer, Extended State Observer},
language = {English},
publisher = {IEEE}
}

This paper presents an extended state observer (ESO) based repetitive controller (RC) to compensate periodic signals, aperiodic disturbances and uncertainties of the plant with relative degree equal or greater than zero. Since linear ESO has only two tuning parameters, the proposed controller provides a simple and user friendly solution to complex engineering problems in practice. Moreover, due to the model free approach of ESO-based control, it can be applied to a wide variety of plants. The design procedures are proposed to ensure a stable system. Various types of disturbances are used in simulations and experiments which show that the ESO-based RC can not only reject periodic and aperiodic disturbances but also handle the plant parameter uncertainty. The comparison studies demonstrate that the ESO-based RC has superb performance.

@conference{dursun_2016,
title = {Position Control by Using PD Type Fuzzy Logic: Experimental Study on Rotary Servo System},
author = {Dursun, E.H.; Durdu, A},
booktitle = {8th International COnference on Electronics, Computers and Artificial Intelligence (ECAI 2016)},
year = {2016},
institution = {Electrical and Electronics Engineering Department, Selcuk University, Turkey},
abstract = {In this paper, real-time position control of rotary servo system is performed by using fuzzy logic. SRV-02 DC servo system produced by Quanser is equipped with a DC motor. Servo system is loading by using various metallic weights and performance analysis are made according to international performance criteria. When making comparison of performance, it is seen that controller which is designed via fuzzy logic shows better results on position control than PID control which is a conventional control method and commonly used industrial applications. },
keywords = {DC Motor; fuzzy logic control; PID; rotary servo system; servo control},
language = {English},
publisher = {IEEE},
isbn = {978-1-5090-2048-5}
}

In this paper, real-time position control of rotary servo system is performed by using fuzzy logic. SRV-02 DC servo system produced by Quanser is equipped with a DC motor. Servo system is loading by using various metallic weights and performance analysis are made according to international performance criteria. When making comparison of performance, it is seen that controller which is designed via fuzzy logic shows better results on position control than PID control which is a conventional control method and commonly used industrial applications.

@conference{verrelli_2016,
title = {Synchronization control of DC motors through adaptive disturbance cancellation techniques},
author = {Verrelli, C.M.; Pirozzi, S.; Tomei, P.; Natale, C.},
booktitle = {2016 International Symposium on Power Electronics, Electrical Drives, Automation and Motion (SPEEDAM)},
year = {2016},
institution = {University of Rome Tor Vergata, Italy},
abstract = {We address the master-slave synchronization control problem for a current-fed DC motor with uncertain parameters: an exogenous rotor position reference signal, which belongs to the class of biased sinusoidal signals with uncertain bias, amplitude, frequency, phase, is to be tracked without assuming its foreknowledge. An innovative use of adaptive disturbance cancellation techniques allows to obtain an output feedback adaptive nonlinear control scheme which simply represents a generalization of the classical internal model- based input law. Analyses from both theoretical and experimental points of view illustrate the effectiveness of the proposed approach. },
keywords = {Master-slave synchronization; DC motors; Output feedback; Adaptive disturbance cancellation},
language = {English},
publisher = {IEEE},
pages = {488 - 493}
}

We address the master-slave synchronization control problem for a current-fed DC motor with uncertain parameters: an exogenous rotor position reference signal, which belongs to the class of biased sinusoidal signals with uncertain bias, amplitude, frequency, phase, is to be tracked without assuming its foreknowledge. An innovative use of adaptive disturbance cancellation techniques allows to obtain an output feedback adaptive nonlinear control scheme which simply represents a generalization of the classical internal model- based input law. Analyses from both theoretical and experimental points of view illustrate the effectiveness of the proposed approach.

@conference{brill_2016_2,
title = {Using inertial and visual sensing from a mounted smartphone to stabilize a ball and beam test-bed},
author = {Brill, A.; Frank, J.A.; Kapila, V.},
booktitle = {2016 American Control Conference},
year = {2016},
institution = {NYU Tandon School of Engineering, Brooklyn, USA},
abstract = {Mobile technology is developing and impacting society at an accelerating pace. Since their release in 2007, over one billion smartphones have reshaped the daily lives of their users and their embedded technologies have become increasingly more powerful and miniaturized with each new model. Yet, the majority of the most popular uses of these devices do not take full advantage of their sensing, storage, computation, and communication (SSCC) capabilities. In this paper, we consider an experimental setup in which a smartphone is mounted to a ball and beam system using a 3D-printed mounting structure attached at each end of the beam. To perform feedback control of the ball and beam system, the smartphone's inertial and camera sensors are used to measure the angular orientation and velocity of the beam and translational position of the ball on the beam. To account for the nonlinear effects added to the system by the presence of the smartphone and its mounting structure, a feedback linearizing controller is used to stabilize the system. Simulation and experimental results are presented to show that smartphones and their various sensors can be integrated in the wireless sensing and control of physical systems as part of an emerging class of smartphone-mounted test-beds for research and education. },
keywords = {Cameras, DC motors, Feedback control, Frequency measurement, Position measurement, Sensors, Velocity measurement},
language = {English},
publisher = {IEEE},
isbn = {978-1-4673-8680-7},
pages = {1335-1340}
}

Mobile technology is developing and impacting society at an accelerating pace. Since their release in 2007, over one billion smartphones have reshaped the daily lives of their users and their embedded technologies have become increasingly more powerful and miniaturized with each new model. Yet, the majority of the most popular uses of these devices do not take full advantage of their sensing, storage, computation, and communication (SSCC) capabilities. In this paper, we consider an experimental setup in which a smartphone is mounted to a ball and beam system using a 3D-printed mounting structure attached at each end of the beam. To perform feedback control of the ball and beam system, the smartphone's inertial and camera sensors are used to measure the angular orientation and velocity of the beam and translational position of the ball on the beam. To account for the nonlinear effects added to the system by the presence of the smartphone and its mounting structure, a feedback linearizing controller is used to stabilize the system. Simulation and experimental results are presented to show that smartphones and their various sensors can be integrated in the wireless sensing and control of physical systems as part of an emerging class of smartphone-mounted test-beds for research and education.

@inproceedings{tavakoli_2015,
title = {An Analysis of Sampling Effect on Bilateral Teleoperation System Transparency},
author = {Yang, Ting; Fu, Yi Li; Tavakoli, Mahdi},
booktitle = {2015 34th Chinese Control Conference (CCC)},
year = {2015},
abstract = {The performances of continuous-time controlled and discrete-time controlled bilateral teleoperation systems are mathematically and experimentally studied and compared. The results show that under stability conditions, continuous-time controlled teleoperation systems have hybrid matrix parameters that are closer to their ideal values than their discrete-time controlled counterparts. This means better force tracking and position tracking performance under continuous-time control, which can lead to better task performance. },
keywords = {Bilateral teleoperation, hybrid parameters, discrete-time control, continuous-time control, system performance},
language = {English},
publisher = {IEEE},
pages = {5896 - 5900}
}

The performances of continuous-time controlled and discrete-time controlled bilateral teleoperation systems are mathematically and experimentally studied and compared. The results show that under stability conditions, continuous-time controlled teleoperation systems have hybrid matrix parameters that are closer to their ideal values than their discrete-time controlled counterparts. This means better force tracking and position tracking performance under continuous-time control, which can lead to better task performance.

@article{yang_2015,
title = {Digital versus analog control of bilateral teleoperation systems:A task performance comparison},
author = {Yang, Ting; Fu, Yili; Tavakoli, Mahdi},
journal = {Control Engineering Practice},
year = {2015},
volume = {38},
abstract = {Controller discretization has the potential to jeopardize the stability of a bilateral teleoperation system. As reported in the literature, stability conditions impose bounds on the gains of the discrete-time controller and the sampling period and also a trade-off between the two. This paper shows a choice of task for which large sampling periods, necessitating low control gains for maintaining stability, lead to low teleoperation transparency and unacceptable task performance. It continues to show that users can successfully perform the same task if the controller is implemented using analog components. This highlights the advantages of analog haptics in tasks involving the display of highly stiff environments. The paper also highlights the constraints in designing analog haptic teleoperation controllers and proposes design guidelines to address them. },
keywords = {Bilateral teleoperation system; continuous-time control; discrete-time control; transparency; task performance},
language = {English},
publisher = {Elsevier Ltd.},
pages = {46-56}
}

Controller discretization has the potential to jeopardize the stability of a bilateral teleoperation system. As reported in the literature, stability conditions impose bounds on the gains of the discrete-time controller and the sampling period and also a trade-off between the two. This paper shows a choice of task for which large sampling periods, necessitating low control gains for maintaining stability, lead to low teleoperation transparency and unacceptable task performance. It continues to show that users can successfully perform the same task if the controller is implemented using analog components. This highlights the advantages of analog haptics in tasks involving the display of highly stiff environments. The paper also highlights the constraints in designing analog haptic teleoperation controllers and proposes design guidelines to address them.

@inproceedings{mosley_2015,
title = {Experimental Investigation of a Time Scales-Based Stability Criterion over Finite Time Horizons},
author = {Mosley, M.; Gravagne, I.; Poulsen, D.; Davis, J.},
booktitle = {Proceedings of the ASME 2015 Dynamic Systems and Control Conference},
year = {2015},
abstract = {Feedback control systems that employ large area networks or other unpredictable or unreliable communications protocols between sensors, actuators, and controllers may experience nonuniform sampling characteristics. Previous work by Poulsen, et. al. gives a criterion for exponential stability of non-uniformly discretized feedback control systems, assuming sample periods drawn from a known statistical distribution. However, the given stability theorem assumes an infinite time horizon. This work therefore examines the exponential stability criterion experimentally, over a finite time horizon, on a 2nd-order servo mechanism. This paper is the first to experimentally investigate the validity of this time scales stability criterion. },
language = {English},
publisher = {ASME}
}

Feedback control systems that employ large area networks or other unpredictable or unreliable communications protocols between sensors, actuators, and controllers may experience nonuniform sampling characteristics. Previous work by Poulsen, et. al. gives a criterion for exponential stability of non-uniformly discretized feedback control systems, assuming sample periods drawn from a known statistical distribution. However, the given stability theorem assumes an infinite time horizon. This work therefore examines the exponential stability criterion experimentally, over a finite time horizon, on a 2nd-order servo mechanism. This paper is the first to experimentally investigate the validity of this time scales stability criterion.

@inproceedings{yang_2015_2,
title = {FPAA-based Control of Bilateral Teleoperation Systems},
author = {Yang, Ting; Fu, Yi Li; Tavakoli, Mahdi},
booktitle = {2015 34th Chinese Control Conference (CCC)},
year = {2015},
abstract = {Discretizing the continuous-time controller of a master-slave teleoperation system can simplify control implementation. However, in teleoperation systems, discrete-time control can cause a performance degradation compared to continuous-time control. In digitally controlled bilateral teleoperation systems, there exist stability-imposed bounds on the gains of the discrete-time controller and the sampling period, and a trade-off between the two. This means that given a sampling period, it is impossible for the discretized controller to have gains above a threshold, which may well be necessary for successful performance of teleoperated tasks requiring highly accurate master-slave position tracking. In a teleoperation system with analog controller, however, stability does not impose any upper bound on the control gains, thus facilitating the performance of tasks that do require highly accurate master-slave position tracking. Inspired by this advantage of analog control, in this paper we develop a Field Programmable Analog Arrays (FPAA) based controller for bilateral teleoperation, which can achieve higher control gain than its discrete-time counterpart. We present the results of a user study measuring the human performance for a task involving flipping a stiff switch through a teleoperation system. We experimentally show that large sampling periods, necessitating low control gains for maintaining stability, lead to unacceptable task performance. We then show that humans can successfully perform the same task with the FPAA-based controller for the teleoperation system. },
keywords = {Bilateral teleoperation, stability, discrete-time control, FPAA-based control, task performance},
language = {English},
publisher = {IEEE},
pages = {5841 - 5845}
}

Discretizing the continuous-time controller of a master-slave teleoperation system can simplify control implementation. However, in teleoperation systems, discrete-time control can cause a performance degradation compared to continuous-time control. In digitally controlled bilateral teleoperation systems, there exist stability-imposed bounds on the gains of the discrete-time controller and the sampling period, and a trade-off between the two. This means that given a sampling period, it is impossible for the discretized controller to have gains above a threshold, which may well be necessary for successful performance of teleoperated tasks requiring highly accurate master-slave position tracking. In a teleoperation system with analog controller, however, stability does not impose any upper bound on the control gains, thus facilitating the performance of tasks that do require highly accurate master-slave position tracking. Inspired by this advantage of analog control, in this paper we develop a Field Programmable Analog Arrays (FPAA) based controller for bilateral teleoperation, which can achieve higher control gain than its discrete-time counterpart. We present the results of a user study measuring the human performance for a task involving flipping a stiff switch through a teleoperation system. We experimentally show that large sampling periods, necessitating low control gains for maintaining stability, lead to unacceptable task performance. We then show that humans can successfully perform the same task with the FPAA-based controller for the teleoperation system.

@article{nounou_214,
title = {A model-free design of reduced-order controllers and application to a DC servomotor},
author = {Sofiane Khadraoui, Hazem Nounou, Mohamed Nounou, Aniruddha Datta, Shankar P. Bhattacharyya},
journal = {Automatica},
year = {2014},
volume = {50},
abstract = {This paper presents a new model-free technique to design fixed-structure controllers for linear unknown systems. In the current control design approaches, measured data are used to first identify a model of the plant, then a controller is designed based on the identified model. Due to errors associated with the identification process, degradation in the controller performance is expected. Hence, we use the measured data to directly design the controller without the need for model identification. Our objective here is to design measurement-based controllers for stable and unstable systems, even when the closed-loop architecture is unknown. This proposed method can be very useful for many industrial applications. The proposed control methodology is a reference model design approach which aims at finding suitable parameter values of a fixed-order controller so that the closed-loop frequency response matches a desired frequency response. This reference model design problem is formulated as a nonlinear programming problem using the concept of bounded error, which can then be solved to find suitable values of the controller parameters. In addition to the well-known advantages of data-based control methods, the main features of our proposed approach are: (1) the error is guaranteed to be bounded, (2) it enables us to avoid issues related to the use of minimization methods, (3) it can be applied to stable and unstable plants and does not require any knowledge about the closed-loop architecture, and (4) the controller structure can be selected a priori, which means that low-order controllers can be designed. The proposed technique is experimentally validated through a real position control problem of a DC servomotor, where the results demonstrate the efficacy of the proposed method. },
keywords = {Model-free control, Unknown control architecture, Reference model design, Low-order control design, Controller tuning, Frequency response, Performance achievement, Control of DC servomotor},
language = {English},
publisher = {Elsevier Ltd.},
pages = {2142-2149}
}

This paper presents a new model-free technique to design fixed-structure controllers for linear unknown systems. In the current control design approaches, measured data are used to first identify a model of the plant, then a controller is designed based on the identified model. Due to errors associated with the identification process, degradation in the controller performance is expected. Hence, we use the measured data to directly design the controller without the need for model identification. Our objective here is to design measurement-based controllers for stable and unstable systems, even when the closed-loop architecture is unknown. This proposed method can be very useful for many industrial applications. The proposed control methodology is a reference model design approach which aims at finding suitable parameter values of a fixed-order controller so that the closed-loop frequency response matches a desired frequency response. This reference model design problem is formulated as a nonlinear programming problem using the concept of bounded error, which can then be solved to find suitable values of the controller parameters. In addition to the well-known advantages of data-based control methods, the main features of our proposed approach are: (1) the error is guaranteed to be bounded, (2) it enables us to avoid issues related to the use of minimization methods, (3) it can be applied to stable and unstable plants and does not require any knowledge about the closed-loop architecture, and (4) the controller structure can be selected a priori, which means that low-order controllers can be designed. The proposed technique is experimentally validated through a real position control problem of a DC servomotor, where the results demonstrate the efficacy of the proposed method.

@conference{mehdi_2014,
title = {Anti-windup compensator schemes for DC servo motor speed control system},
author = {Mehdi, N.; Malik, F.M.; Salman, M.; Rehan, M.; Qaiser, N.},
booktitle = {2014 International Conference on Robotics and Emerging Allied Technologies in Engineering (iCREATE)},
year = {2014},
abstract = {This paper deals with design, simulation and implementation of anti-windup compensator (AWe) schemes for speed control of a DC servo motor. AWC is an auxiliary controller that ensures stability and performance in the event of input saturation which in turn cause windup. Three anti-windup compensator (AWC) schemes have been implemented to overcome the windup effects namely robust AWe, internal model control (IMC) based AWC and static AWC. Schemes are decoupled architecture based. Linear Matrix Inequalities (LMIs) are required to be solved to obtain the compensator gain for the robust and static AWCs. IMC based approach uses the plant dynamics to compensate for the input saturation effects. Further a comprehensive comparison of all the schemes has been included. Hardware-in-loop (HIL) simulations give an industrial and academic importance to this work. },
keywords = {Anti-windup compensator; Decoupled architecture; Linear matrix inequality; DC servo motor},
language = {English},
publisher = {IEEE},
isbn = {978-1-4799-5131-4},
pages = {277 - 282}
}

This paper deals with design, simulation and implementation of anti-windup compensator (AWe) schemes for speed control of a DC servo motor. AWC is an auxiliary controller that ensures stability and performance in the event of input saturation which in turn cause windup. Three anti-windup compensator (AWC) schemes have been implemented to overcome the windup effects namely robust AWe, internal model control (IMC) based AWC and static AWC. Schemes are decoupled architecture based. Linear Matrix Inequalities (LMIs) are required to be solved to obtain the compensator gain for the robust and static AWCs. IMC based approach uses the plant dynamics to compensate for the input saturation effects. Further a comprehensive comparison of all the schemes has been included. Hardware-in-loop (HIL) simulations give an industrial and academic importance to this work.

@conference{flores_2014,
title = {Conventional Compensators Design Using Newton’s Method},
author = {Flores Esmael; Castro, Renato Ely; Chaves, Luciano Fonseca},
booktitle = {2014 11th World Congress on Intelligent Control and Automation (WCICA)},
year = {2014},
abstract = {Recently, several charts were created in order to assist the design of numerous conventional compensators. In particular, a universal chart was developed to cover the project of various types of conventional compensators, aiming to eliminate trial-and-error methods present in the literature of the control systems disciplines in undergraduate courses. This paper demonstrates how Newton's method can be used to eliminate visual search, allowing the numerical search of compensator parameters in the universal chart. If the plant model is not known, the method of least squares is used as a tool for identification of systems in order to obtain the frequency response of the plant This allows to identify the dynamics of the plant and specify a series type compensator, providing the solutions in a transitory and steady state. The algorithm developed in Matlab environment has its experimental validation performed using a Quanser SRV02 Servomotor speed control system. This new project technique is easy to implement and can be used both in industry and in teaching as an alternative to the classic design methods present in the literature. },
keywords = {Compensators Design, Frequency Response, Least Squares Method, Newton's Method,Servomotor Quanser SRV02,Identication of Systems},
language = {English},
publisher = {IEEE},
pages = {4350 - 4355}
}

Recently, several charts were created in order to assist the design of numerous conventional compensators. In particular, a universal chart was developed to cover the project of various types of conventional compensators, aiming to eliminate trial-and-error methods present in the literature of the control systems disciplines in undergraduate courses. This paper demonstrates how Newton's method can be used to eliminate visual search, allowing the numerical search of compensator parameters in the universal chart. If the plant model is not known, the method of least squares is used as a tool for identification of systems in order to obtain the frequency response of the plant This allows to identify the dynamics of the plant and specify a series type compensator, providing the solutions in a transitory and steady state. The algorithm developed in Matlab environment has its experimental validation performed using a Quanser SRV02 Servomotor speed control system. This new project technique is easy to implement and can be used both in industry and in teaching as an alternative to the classic design methods present in the literature.