scholarly journals Temperature Control of Continuous Chemical Reactors Under Noisy Measurements and Model Uncertainties

2012 ◽  
Vol 10 (3) ◽  
Author(s):  
Ricardo Aguilar López ◽  
Rafael Martínez Guerra ◽  
Juan L. Mata Machuca
Keyword(s):  
Sliding Mode ◽  
System Stability ◽  
Chemical System ◽  
Control Law ◽  
Model Uncertainties ◽  
Uncertainty Estimator ◽  
The Face ◽  
Oscillatory Chemical ◽  
Error Dynamics ◽  
Noisy Measurements

The aim of this paper is to present the synthesis of a robust control law for the control of a class of nonlinear systems named Liouvillian. The control design is based on a sliding-mode uncertainty estimator developed under the framework of algebraic-differential concepts. The estimation convergence is done by the Lyapunov-type analysis and the closed-loop system stability is shown by means of the regulation error dynamics. Robustness of the proposed control scheme is tested in the face of noise output measurements and model uncertainties. The performance of the proposed control law is illustrated with numerical simulations in which a class of oscillatory chemical system is used as application example.

Disturbance Adaptive Discrete-Time Sliding Control With Application to Engine Speed Control

1998 ◽  
Vol 123 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Mooncheol Won ◽  
J. K. Hedrick
Keyword(s):  
Nonlinear Systems ◽  
Discrete Time ◽  
Control Method ◽  
Sliding Mode ◽  
Input Saturation ◽  
Adaptive Sliding Mode Control ◽  
Control Law ◽  
Sliding Surface ◽  
Sliding Control ◽  
Error Dynamics

This paper presents a discrete-time adaptive sliding control method for SISO nonlinear systems with a bounded disturbance or unmodeled dynamics. Control and adaptation laws considering input saturation are obtained from approximately discretized nonlinear systems. The developed disturbance adaptation or estimation law is in a discrete-time form, and differs from that of conventional adaptive sliding mode control. The closed-loop poles of the feedback linearized sliding surface and the adaptation error dynamics can easily be placed. It can be shown that the adaptation error dynamics can be decoupled from sliding surface dynamics using the proposed scheme. The proposed control law is applied to speed tracking control of an automatic engine subject to unknown external loads. Simulation and experimental results verify the advantages of the proposed control law.

scholarly journals Autopilot Design for a Compound Control Small-Scale Solid Rocket in the Initial Stage of Launch

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Tian Dong ◽  
Changjian Zhao ◽  
Zhiguo Song
Keyword(s):  
Sliding Mode Control ◽  
Sliding Mode ◽  
System Stability ◽  
Small Scale ◽  
Control Law ◽  
Rolling Moment ◽  
Mode Control ◽  
Compound Control ◽  
Initial Stage ◽  
Solid Rocket

In this paper, an autopilot design method for a compound control small-scale solid rocket is proposed. The rocket has multiple actuators, including a flexible nozzle for pitching and yawing channels, aerodynamic fins for rolling channel, and lateral thrusters which work in on-off mode for all three channels. In order to keep the aircraft steady in the initial stage of launch when the dynamic pressure is low, the autopilot is aimed at optimizing the cooperation among the actuators. Firstly, without considering the discontinuous lateral thrust, the control law for flexible nozzle and aerodynamic fins is achieved via the sliding mode control approach. On this basis, an object to be controlled with choiceness is obtained for the lateral thrusters controlled loop. Secondly, the operation logic of lateral thrusters is programmed, regarding rolling moment as priority. Thirdly, after a continuous controller is obtained, a discretization method for the lateral thrusters control law is designed combining the characteristics of sliding mode control and Lyapunov’s stableness theorem. Finally, the fundamental cause why compound control improves the system stability is given theoretically. Simulation results validate the improved response performance and robustness against uncertainties and disturbance of the autopilot.

scholarly journals Design and Stability Analysis of a Robust-Adaptive Sliding Mode Control Applied on a Robot Arm with Flexible Links

Vibration ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 1-19
Author(s):  
Çağlar Uyulan
Keyword(s):  
Sliding Mode ◽  
Robust Stabilization ◽  
Unmodeled Dynamics ◽  
Control Law ◽  
Robot Arm ◽  
Flexible Robot ◽  
Model Uncertainties ◽  
Actuator Dynamics ◽  
Chattering Free ◽  
Robust Adaptive

Modelling errors and robust stabilization/tracking problems under parameter and model uncertainties complicate the control of the flexible underactuated systems. Chattering-free sliding-mode-based input-output control law realizes robustness against the structured and unstructured uncertainties in the system dynamics and avoids the excitation of unmodeled dynamics. The main purpose of this paper was to propose a robust adaptive solution for stabilizing and tracking direct-drive (DD) flexible robot arms under parameter and model uncertainties, as well as external disturbances. A lightweight robot arm subject to external and internal dynamic effects was taken into consideration. The challenges were compensating actuator dynamics with the inverter switching effects and torque ripples, stabilizing the zero dynamics under parameter/model uncertainties and disturbances while precisely tracking the predefined reference position. The precise control of this kind of system demands an accurate system model and knowledge of all sources that excite unmodeled dynamics. For this purpose, equations of motion for a flexible robot arm were derived and formulated for the large motion via Lagrange’s method. The goals were determined to achieve high-speed, precise position control, and satisfied accuracy by compensating the unwanted torque ripple and friction that degrades performance through an adaptive robust control approach. The actuator dynamics and their effect on the torque output were investigated due to the transmitted torque to the load side. The high-performance goals, precision and robustness issues, and stability concerns were satisfied by using robust-adaptive input-output linearization-based control law combining chattering-free sliding mode control (SMC) while avoiding the excitation of unmodeled dynamics. The following highlights are covered: A 2-DOF flexible robot arm considering actuator dynamics was modelled; the theoretical implication of the chattering-free sliding mode-adaptive linearizing algorithm, which ensures robust stabilization and precise tracking control, was designed based on the full system model including actuator dynamics with computer simulations. Stability analysis of the zero dynamics originated from the Lyapunov theorem was performed. The conceptual design necessity of nonlinear observers for the estimation of immeasurable variables and parameters required for the control algorithms was emphasized.

Robust output tracking of nonlinear systems with transient improvement via funnel-based sliding mode control

2020 ◽  
Vol 42 (16) ◽  
pp. 3225-3233
Author(s):  
Mehdi Zahedi ◽  
Tahereh Binazadeh
Keyword(s):  
Nonlinear Systems ◽  
Sliding Mode Control ◽  
Sliding Mode ◽  
Model Uncertainties ◽  
External Disturbances ◽  
Output Tracking ◽  
Mode Control ◽  
Transient Improvement ◽  
The Face ◽  
Funnel Control

This paper studies a new procedure for robust tracking of nonlinear systems. This procedure is based on the combination of the sliding mode control and the funnel control, which in addition to the robust performance of the closed-loop system in the face of model uncertainties and/or external disturbances also leads to improvement of the characteristics of the transient responses. Using funnel control and the appropriate choice of the funnel can affect the convergence rate and overshoot. In this regard, a theorem has been presented and the effective performances of the suggested controller have been guaranteed in various respects based on exact mathematical analysis. Simulations have also been carried out to illustrate the efficiency of the proposed approach and to verify the theoretical achievements of the paper despite model uncertainties and external disturbances.

Sliding Mode Control of Magnetic Bearing System Based on Variable Rate Reaching Law

2011 ◽  
Vol 460-461 ◽  
pp. 827-830 ◽  
Author(s):  
Jing Feng Mao ◽  
Ai Hua Wu ◽  
Guo Qing Wu ◽  
Xu Dong Zhang
Keyword(s):  
Sliding Mode Control ◽  
Control Method ◽  
Sliding Mode ◽  
Magnetic Bearing ◽  
System Stability ◽  
Control Law ◽  
Variable Rate ◽  
Reaching Law ◽  
Mode Control ◽  
Bearing System

In order to eliminate the chattering phenomena caused by conventional sliding mode control (SMC) method in magnetic bearing system control, this paper proposes a variable rate reaching law approach based sliding mode controller to achieve higher system stability and robustness. In this control law, system states’ normal numbers are brought in to automatic adjust the gain of the switching control part of SMC. The controller output amplitude of chattering can be progressively damped, and the system will converge to zero asymptotically. The system stability is proved by Laypunov theory, and the prerequisite of control law parameters design is deduced out. Simulation results show that the proposed SMC control method has effectiveness in dynamic suspension position tracking performance and obtaining system robustness.

scholarly journals Design and Stability Analysis of a Robust-Adaptive Sliding Mode Control Applied on a Robot Arm with Flexible Links

2021 ◽  
Author(s):  
Çağlar Uyulan ◽  
Batuhan İpek
Keyword(s):  
Sliding Mode ◽  
Unmodeled Dynamics ◽  
Control Law ◽  
Robot Arm ◽  
Input Output ◽  
Flexible Robot ◽  
Model Uncertainties ◽  
Actuator Dynamics ◽  
Chattering Free ◽  
Robust Adaptive

Modelling errors, robust stabilization/tracking problems under parameter and model uncertainties complicate the control of the flexible underactuated systems. Chattering-free sliding-mode based input-output control law realizes robustness against the structured and unstructured uncertainties in the system dynamics and avoids excitation of unmodeled dynamics. The main purpose is to propose a robust adaptive solution for stabilizing and tracking direct-drive (DD) flexible robot arms under parameter and model uncertainties, as well as external disturbances. A lightweight robot arm subject to external and internal dynamic effects was taken into consideration. The challenges are compensating actuator dynamics with the inverter switching effects and torque ripples, stabilizing the zero dynamics under parameter/model uncertainties and disturbances while precisely track the predefined reference position. The precise control of this kind of system demands an accurate system model and knowledge of all sources that excite unmodeled dynamics. For this purpose, equations of motion for a flexible robot arm were derived and formulated for the large motion via Lagrange’s method. The goals were determined to achieve high-speed, precise position control, and satisfied accuracy by compensating the unwanted torque ripple and friction that degrades performance through an adaptive robust control approach. The actuator dynamics and their effect on the torque output were investigated due to the transmitted torque to the load side. The high-performance goals, precision&robustness issues, and stability concerns were satisfied by using robust-adaptive input-output linearization-based control law combining chattering-free sliding mode control (SMC) while avoiding the excitation of unmodeled dynamics.

scholarly journals Inverse Optimal Attitude Stabilization of Flexible Spacecraft with Actuator Saturation

2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
Chutiphon Pukdeboon
Keyword(s):  
Actuator Saturation ◽  
Sliding Mode ◽  
Estimation Error ◽  
Flexible Spacecraft ◽  
Control Law ◽  
Optimal Control Strategy ◽  
External Disturbances ◽  
Control Lyapunov Function ◽  
Error Dynamics ◽  
The Stability

This paper presents a new robust inverse optimal control strategy for flexible spacecraft attitude maneuvers in the presence of external disturbances and actuator constraint. A new constrained attitude controller for flexible spacecraft is designed based on the Sontag-type formula and a control Lyapunov function. This control law optimizes a meaningful cost functional and the stability of the resulting closed-loop system is ensured by the Lyapunov framework. A sliding mode disturbance observer is used to compensate unknown bounded external disturbances. The ultimate boundedness of estimation error dynamics is guaranteed via a rigorous Lyapunov analysis. Simulation results are provided to demonstrate the performance of the proposed control law.

scholarly journals Combined Neural Network and PD Adaptive Tracking Controller for Ship Steering System

2017 ◽  
Vol 13 (1) ◽  
pp. 59-66 ◽  
Author(s):  
Abdul-Basset Al- Hussein
Keyword(s):  
Neural Network ◽  
Sliding Mode ◽  
Rbf Neural Network ◽  
Approximation Error ◽  
System Stability ◽  
Stability And Convergence ◽  
Control Law ◽  
Adaptive Tracking ◽  
Uncertain Dynamics ◽  
Tracking Controller

In this paper, a combined RBF neural network sliding mode control and PD adaptive tracking controller is proposed for controlling the directional heading course of a ship. Due to the high nonlinearity and uncertainty of the ship dynamics as well as the effect of wave disturbances a performance evaluation and ship controller design is stay difficult task. The Neural network used for adaptively learn the uncertain dynamics bounds of the ship and their output used as part of the control law moreover the PD term is used to reduce the effect of the approximation error inherited in the RBF networks. The stability of the system with the combined control law guaranteed through Lyapunov analysis. Numeric simulation results confirm the proposed controller provide good system stability and convergence.

Cooperative control of multi-agent systems with time-delays

2018 ◽  
Author(s):  
◽  
Zhentao Xie
Keyword(s):  
Time Delay ◽  
Cooperative Control ◽  
Sliding Mode ◽  
Control Algorithms ◽  
Control Law ◽  
Time Varying ◽  
Multi Agent Systems ◽  
Model Uncertainties ◽  
Time Varying Delay ◽  
Varying Delay

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] In this dissertation, we designed two cooperative control algorithms for multi-agent systems with time-delays. The first one is Robust Sliding-Mode Cooperative Control for Multiple Time-Delay Systems with Model Uncertainties and Disturbance, in which, it designed a sliding mode cooperative control law for a general time-delay system with model uncertainty and external disturbance. For the delay-independent system, a sliding surface is constructed and a feasible solution to the LMI based on the Lyapunov stability theory is derived. The model uncertainty term is included in the control design by using a matrix factorization method. The second one is Cooperative Control for Multiple Agents with Time Varying Delay and Model Uncertainties, in which, it designed a cooperative control law for distributed multiple agents to follow a leader consensually under time-varying delay and model uncertainties. Comparing with the first control law design, our first promotion is to design a consensus control law for leader followers under time delay dependent case, which releases the two constraint conditions, which are the flaws in previous works. Our second promotion is that we take the time varying delay into consideration. In addition to the theoretical study, we also did experiment test of the cooperative control algorithms on Quadrotor-UAVs. We tested the system stability and the time-delay effects on systems. The results proved the validity of the designed control algorithms.

Distributed attitude consensus tracking control for spacecraft formation flying via adaptive nonsingular fast terminal sliding mode control

2021 ◽  
pp. 095441002110422
Author(s):  
Xiong Xie ◽  
Tao Sheng ◽  
Liang He ◽  
Zhijun Chen ◽  
Yong Zhao
Keyword(s):  
Tracking Control ◽  
Sliding Mode ◽  
Control Law ◽  
Model Uncertainties ◽  
External Disturbances ◽  
Terminal Sliding Mode ◽  
Spacecraft Formation ◽  
Spacecraft Formation Flying ◽  
Consensus Tracking ◽  
Fast Terminal Sliding Mode

This article investigates the distributed attitude consensus tracking control for spacecraft formation flying with unknown external disturbances and model uncertainties. First, a terminal sliding mode disturbance observer (TSMDO) is constructed to estimate the generalized disturbances including external disturbances and model uncertainties. The finite-time convergence of the estimation errors using TSMDO is analyzed. Second, a variable structure control law is developed to avoid introducing initial errors of the TSMDO. Third, a novel adaptive nonsingular fast terminal sliding mode (ANFTSM) control law based on TSMDO is proposed to ensure the convergence of attitude tracking errors to zero. Based on theoretical analysis, the finite-time stability can be guaranteed by Lyapunov theory. Finally, the effectiveness of the developed control law is verified via numerical simulations.

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