@article{wang_2020,
title = {Bounded UDE-based Controller for Input Constrained Systems with Uncertainties and Disturbances},
author = {Wang, Y.; Ren, B.; Zhong, Q.-C.},
journal = {IEEE Transactions on Industrial Electronics},
year = {2020},
institution = {Texas Tech University, USA; Illinois Institute of Technology, USA},
abstract = {The uncertainty and disturbance estimator (UDE)-based controller has emerged as an effective robust control method to handle systems with uncertainties and disturbances. However, similar to other controllers including an integral action, the UDE-based controller faces the integral windup issue when the system has input constraints. In this paper, a bounded UDE-based controller is proposed to deal with systems subject to uncertainties, disturbances and input constraint. An additional time-varying variable is introduced into the design of the error dynamics to naturally avoid integral windup. The boundedness design guarantees that both the final controller output and the additional time-varying variable dynamically move on an ellipse so that the controller output always satisfies the input constraint. The proposed bounded UDE-based controller inherits the robustness of the conventional UDE-based control method, and has a clear structure, with guidelines provided for parameter selections. Both theoretical analysis and experimental results are provided to validate the proposed design. },
issn = {0278-0046},
keywords = {Uncertainty and disturbance estimator (UDE), boundedness design, input constraint, integral windup},
language = {English},
publisher = {IEEE}
}

The uncertainty and disturbance estimator (UDE)-based controller has emerged as an effective robust control method to handle systems with uncertainties and disturbances. However, similar to other controllers including an integral action, the UDE-based controller faces the integral windup issue when the system has input constraints. In this paper, a bounded UDE-based controller is proposed to deal with systems subject to uncertainties, disturbances and input constraint. An additional time-varying variable is introduced into the design of the error dynamics to naturally avoid integral windup. The boundedness design guarantees that both the final controller output and the additional time-varying variable dynamically move on an ellipse so that the controller output always satisfies the input constraint. The proposed bounded UDE-based controller inherits the robustness of the conventional UDE-based control method, and has a clear structure, with guidelines provided for parameter selections. Both theoretical analysis and experimental results are provided to validate the proposed design.

@conference{salazar-aquino_2020,
title = {Position Control of a 2DOF Rotary Torsion Plant Using a 2DOF Fractional Order PID Controller},
author = {Salazar-Aquino, O.; Pampamallco-Jara, J.; Rojas-Moreno, A.},
booktitle = {2020 IEEE XXVII International Conference on Electronics, Electrical Engineering and Computing (INTERCON)},
year = {2020},
institution = {Universidad de Ingenieria y Tecnologia (UTEC), Peru},
abstract = {In this paper, a 2DOF FO PID (2 Degrees of Freedom Fractional Order Proportional Integral Derivative) controller is employed to control the angular position of the rotational load of a 2DOF rotary torsion plant. This plant comprises a DC servomotor with gear reduction device anchored to a cubic solid aluminium frame. The horizontal output shaft of the servomotor, acting as a driver, is in series with two rotary torsion loads using two flexible couplings. Every flexible load constitutes a 1DOF. The angular position of the rotary load of the plant is also controlled employing a 2DOF IO (Integer Order) PID controller. In this work, a FO PID controller is obtained from an IO PID controller replacing in the latter controller all its IO derivative and integral terms by FO terms. According to the experimental results obtained in this work, the controlled output of the 2DOF FO PID control systems presents less settling time and steady–state error compared with the controlled output of the 2DOF IO PID control system. },
keywords = {2 DOF PID controller, fractional order controller, integer order controller, 2 DOF rotary torsion plant},
language = {English},
publisher = {IEEE},
isbn = {978-1-7281-9378-6}
}

In this paper, a 2DOF FO PID (2 Degrees of Freedom Fractional Order Proportional Integral Derivative) controller is employed to control the angular position of the rotational load of a 2DOF rotary torsion plant. This plant comprises a DC servomotor with gear reduction device anchored to a cubic solid aluminium frame. The horizontal output shaft of the servomotor, acting as a driver, is in series with two rotary torsion loads using two flexible couplings. Every flexible load constitutes a 1DOF. The angular position of the rotary load of the plant is also controlled employing a 2DOF IO (Integer Order) PID controller. In this work, a FO PID controller is obtained from an IO PID controller replacing in the latter controller all its IO derivative and integral terms by FO terms. According to the experimental results obtained in this work, the controlled output of the 2DOF FO PID control systems presents less settling time and steady–state error compared with the controlled output of the 2DOF IO PID control system.

@conference{rojas-moreno_2018,
title = {Control of the Angular Position of a Rotary Torsion Plant Using a 2DOF FO PID Controller},
author = {Rojas–Moreno, A.; Salazar–Aquino, O.; Pampamallco–Jara, J.},
booktitle = {2018 IEEE 38th Central America and Panama Convention (CONCAPAN XXXVIII)},
year = {2018},
institution = {Universidad de Ingenieria y Tecnologia, Lima, Peru},
abstract = {In this paper, a 2DOF FO PID (2 Degrees of Freedom Fractional Order Proportional Integral Derivative) controller is employed to control the angular position of the rotational load of a rotary torsion plant. Such a plant comprises a DC servomotor with gear train mounted on a cubic solid aluminium frame. The horizontal shaft of the servo is able to rotate a flexible coupling attached to a rotational load. The 2DOF IO (Integer Order) PID controller becomes a 2DOF FO PID controller by making fractional all derivative and integral terms of the algorithm. This work compares experimentally the control performances of the 2DOF FO PID and the 2DOF IO PID feedback control systems. The obtained results proved that the FO 2DOF PID controller performs better because such a controller couses the controlled output, the angular position of the rotary load, to show a lower percent overshoot as well as a shorter settling time. },
keywords = {Feedback control, Servomotors, Shafts, Tuning, PI control, PD control, Couplings},
language = {English},
publisher = {IEEE},
isbn = {978-1-5386-6123-9 }
}

In this paper, a 2DOF FO PID (2 Degrees of Freedom Fractional Order Proportional Integral Derivative) controller is employed to control the angular position of the rotational load of a rotary torsion plant. Such a plant comprises a DC servomotor with gear train mounted on a cubic solid aluminium frame. The horizontal shaft of the servo is able to rotate a flexible coupling attached to a rotational load. The 2DOF IO (Integer Order) PID controller becomes a 2DOF FO PID controller by making fractional all derivative and integral terms of the algorithm. This work compares experimentally the control performances of the 2DOF FO PID and the 2DOF IO PID feedback control systems. The obtained results proved that the FO 2DOF PID controller performs better because such a controller couses the controlled output, the angular position of the rotary load, to show a lower percent overshoot as well as a shorter settling time.

@article{ahn_2018,
title = {Hankel-Norm Approach to Robust FIR Estimation of Dynamic Systems Under External Disturbances},
author = {Ahn, C.K.;Shmaliy, Y.; Zhao, S.},
journal = {IEEE/ASME Transactions on Mechatronics},
year = {2018},
institution = {Korea University, Korea; Universidad de Guanajuato, Mexico; Jiangnan University, China},
abstract = {We propose and develop a new Hankel-norm approach to the robust receding horizon (RH) finite impulse response (FIR) filter design in discrete-time state space under intensive external disturbances. A new condition is developed for the RH Hankel-norm FIR filter (HNFF) design based on the linear matrix inequality and an equality constraint. The proposed RH HNFF ensures unwanted memory reduction and reduces the effect of memory on errors caused by past disturbances. Another condition is also examined to avoid using the equality constraint. The approach is tested and compared with existing filters based on a numerical example to verify its high robustness against unpredictable model changes for an F-404 turbofan engine system model. An experimental study on the one-degree-of-freedom (1-DOF) torsion system is also provided to demonstrate its validity. },
keywords = {Hankel norm, receding horizon, finite impulse response, filtering, robustness, deadbeat prope},
language = {English},
publisher = {IEEE}
}

We propose and develop a new Hankel-norm approach to the robust receding horizon (RH) finite impulse response (FIR) filter design in discrete-time state space under intensive external disturbances. A new condition is developed for the RH Hankel-norm FIR filter (HNFF) design based on the linear matrix inequality and an equality constraint. The proposed RH HNFF ensures unwanted memory reduction and reduces the effect of memory on errors caused by past disturbances. Another condition is also examined to avoid using the equality constraint. The approach is tested and compared with existing filters based on a numerical example to verify its high robustness against unpredictable model changes for an F-404 turbofan engine system model. An experimental study on the one-degree-of-freedom (1-DOF) torsion system is also provided to demonstrate its validity.

@article{elumalai_2017,
title = {A new algebraic LQR weight selection algorithm for tracking control of 2 DoF torsion system},
author = {Elumalai V.K.; Subramanian, R.G.},
journal = {Archives of Electrical Engineering},
year = {2017},
volume = {66},
number = {1},
institution = {VIT University, India; Eindhoven University of Technology, The Netherlands},
abstract = {This paper proposes a novel linear quadratic regulator (LQR) weight selection algorithm by synthesizing the algebraic Riccati equation (ARE) with the Lagrange multiplier method for command following applications of a 2 degree of freedom (DoF) torsion system. The optimal performance of LQR greatly depends on the elements of weighting matrices Q and R. However, normally these weighting matrices are chosen by a trial and error approach which is not only time consuming but cumbersome. Hence, to address this issue, blending the design criteria in time domain with the ARE, we put forward an algebraic weight selection algorithm, which makes the LQR design both simple and modular. Moreover, to estimate the velocity of a servo angle, a high gain observer (HGO) is designed and integrated with the LQR control scheme. The efficacy of the proposed control scheme is tested on a benchmark 2 DoF torsion system for a trajectory tracking application. Both the steady state and dynamic characteristics of the proposed controller are assessed. The experimental results accentuate that the proposed HGO based LQR scheme can guarantee the system to attain the design requirements with minimal vibrations and tracking errors. },
keywords = {ARE, high gain observer, LQR, Q and R matrices, 2 DoF torsion system, trajectory tacking},
language = {English}
}

This paper proposes a novel linear quadratic regulator (LQR) weight selection algorithm by synthesizing the algebraic Riccati equation (ARE) with the Lagrange multiplier method for command following applications of a 2 degree of freedom (DoF) torsion system. The optimal performance of LQR greatly depends on the elements of weighting matrices Q and R. However, normally these weighting matrices are chosen by a trial and error approach which is not only time consuming but cumbersome. Hence, to address this issue, blending the design criteria in time domain with the ARE, we put forward an algebraic weight selection algorithm, which makes the LQR design both simple and modular. Moreover, to estimate the velocity of a servo angle, a high gain observer (HGO) is designed and integrated with the LQR control scheme. The efficacy of the proposed control scheme is tested on a benchmark 2 DoF torsion system for a trajectory tracking application. Both the steady state and dynamic characteristics of the proposed controller are assessed. The experimental results accentuate that the proposed HGO based LQR scheme can guarantee the system to attain the design requirements with minimal vibrations and tracking errors.

@article{zhao2_2016,
title = {Fusion Kalman/UFIR Filter for State Estimation with Uncertain Parameters and Noise Statistics},
author = {Zhao, S.; Shmaliy, Y.; Shi, P.; Ahn C.K.},
journal = {IEEE Transactions on Industrial Electronics},
year = {2016},
institution = {Universidad de Guanajuato, Mexico},
abstract = {In this paper, we fuse the Kalman filter (KF) which is optimal but not robust with the unbiased finite impulse response (UFIR) filter which is more robust than KF but not optimal. The fusion filter employs the KF and UFIR filter as sub-filters and produces smaller errors under the industrial conditions. In order to provide best fusion effect, the operation point where UFIR meets Kalman is determined by applying probabilistic weights to each subfilter. Extensive simulations of the 3-degree of freedom (3- DOF) hover system have shown that the fusion filter output tends to range close to that by the best sub-filter. Experimental verification provided for a 1-DOF torsion system have confirmed validity of simulation. },
issn = {0278-0046},
keywords = {Fusion filter, State estimation, Industrial conditions, Kalman filter, UFIR filter},
language = {English},
publisher = {IEEE}
}

In this paper, we fuse the Kalman filter (KF) which is optimal but not robust with the unbiased finite impulse response (UFIR) filter which is more robust than KF but not optimal. The fusion filter employs the KF and UFIR filter as sub-filters and produces smaller errors under the industrial conditions. In order to provide best fusion effect, the operation point where UFIR meets Kalman is determined by applying probabilistic weights to each subfilter. Extensive simulations of the 3-degree of freedom (3- DOF) hover system have shown that the fusion filter output tends to range close to that by the best sub-filter. Experimental verification provided for a 1-DOF torsion system have confirmed validity of simulation.

@article{fuchs_2013,
title = {Application of the Modern Taylor Series Method to a multi-torsion chain},
author = {Fuchs, G.; Satek, V.; Vopenka, V.; Kunovsky, J.; Kozek, M.},
journal = {Simulation Modelling Practice and Theory},
year = {2013},
volume = {33},
abstract = {In this paper the application of a novel high accuracy numerical integration method is presented for a practical mechanical engineering application. It is based on the direct use of the Taylor series. The main idea is a dynamic automatic order setting, i.e. using as many Taylor series terms for computing as needed to achieve the required accuracy. Previous results have already proved that this numerical solver is both very accurate and fast. In this paper the performance is validated for a real engineering assembly and compared to a Jacobian power series method. The chosen experiment setup is a multi-torsional oscillator chain which reproduces typical dynamic behavior of industrial mechanical engineering problems. Its rotatory dynamics are described by linear differential equations. For the test series the system is operated in a closed-loop configuration. A reference solution of the linear differential equations of the closed-loop system for the output variable is obtained with the mathematical software tool Maple and validated by comparison to measurements from the experiment. The performance of the Modern Taylor Series Method is demonstrated by comparison to standard fixed-step numerical integration methods from the software tool Matlab/Simulink and to the Jacobian power series approximation. Furthermore, the improvement in numerical accuracy as well as stability is illustrated and CPU-times for the different methods are given. },
keywords = {simulation, Taylor series, numerical integration, torsional chain},
language = {English},
publisher = {Elsevier Ltd.},
pages = {89-101}
}

In this paper the application of a novel high accuracy numerical integration method is presented for a practical mechanical engineering application. It is based on the direct use of the Taylor series. The main idea is a dynamic automatic order setting, i.e. using as many Taylor series terms for computing as needed to achieve the required accuracy. Previous results have already proved that this numerical solver is both very accurate and fast. In this paper the performance is validated for a real engineering assembly and compared to a Jacobian power series method. The chosen experiment setup is a multi-torsional oscillator chain which reproduces typical dynamic behavior of industrial mechanical engineering problems. Its rotatory dynamics are described by linear differential equations. For the test series the system is operated in a closed-loop configuration. A reference solution of the linear differential equations of the closed-loop system for the output variable is obtained with the mathematical software tool Maple and validated by comparison to measurements from the experiment. The performance of the Modern Taylor Series Method is demonstrated by comparison to standard fixed-step numerical integration methods from the software tool Matlab/Simulink and to the Jacobian power series approximation. Furthermore, the improvement in numerical accuracy as well as stability is illustrated and CPU-times for the different methods are given.