Adaptive sliding tracking control for nonlinear uncertain robotic systems with unknown actuator nonlinearities

Robotica ◽  
2021 ◽  
pp. 1-20
Author(s):  
Shubo Liu ◽  
Guoquan Liu ◽  
Shengbiao Wu
Keyword(s):  
Control Problem ◽  
Prior Knowledge ◽  
Control Strategy ◽  
Tracking Control ◽  
Disturbance Observer ◽  
Tracking Error ◽  
Small Neighborhood ◽  
Robotic Systems ◽  
Actuator Nonlinearities ◽  
Simulation Results

Abstract This study is concerned with the tracking control problem for nonlinear uncertain robotic systems in the presence of unknown actuator nonlinearities. A novel adaptive sliding controller is designed based on a robust disturbance observer without any prior knowledge of actuator nonlinearities and system dynamics. The proposed control strategy can guarantee that the tracking error eventually converges to an arbitrarily small neighborhood of zero. Simulation results are included to demonstrate the effectiveness and superiority of the proposed strategy.

scholarly journals Online Optimal Control of Robotic Systems with Single Critic NN-Based Reinforcement Learning

Complexity ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Xiaoyi Long ◽  
Zheng He ◽  
Zhongyuan Wang
Keyword(s):  
Optimal Control ◽  
Reinforcement Learning ◽  
Tracking Control ◽  
Learning Algorithm ◽  
Tracking Error ◽  
Adaptive Dynamic Programming ◽  
Robotic Systems ◽  
Control Synthesis ◽  
Optimal Tracking ◽  
Optimal Tracking Control

This paper suggests an online solution for the optimal tracking control of robotic systems based on a single critic neural network (NN)-based reinforcement learning (RL) method. To this end, we rewrite the robotic system model as a state-space form, which will facilitate the realization of optimal tracking control synthesis. To maintain the tracking response, a steady-state control is designed, and then an adaptive optimal tracking control is used to ensure that the tracking error can achieve convergence in an optimal sense. To solve the obtained optimal control via the framework of adaptive dynamic programming (ADP), the command trajectory to be tracked and the modified tracking Hamilton-Jacobi-Bellman (HJB) are all formulated. An online RL algorithm is the developed to address the HJB equation using a critic NN with online learning algorithm. Simulation results are given to verify the effectiveness of the proposed method.

A Heuristic Study of Relegation of Control in Constrained Robotic Systems

1987 ◽  
Vol 109 (3) ◽  
pp. 224-231 ◽  
Author(s):  
H. Hemami ◽  
C. Wongchaisuwat ◽  
J. L. Brinker
Keyword(s):  
Computer Simulation ◽  
Control Problem ◽  
Control Strategy ◽  
Digital Computer ◽  
Robotic Systems ◽  
Independent Control ◽  
Mechanical Coupling ◽  
Heuristic Study ◽  
Separate Control ◽  
Planar Robot

A major control problem in the robotic field is the simultaneous and independent control of constrained trajectories and forces of constraint. The trajectories and the forces are related through the mechanical structure of the system. The task of the controller is to influence the mechanical coupling and allow separate control of the trajectories and the forces. A feasible control strategy is by relegation of control to the state or to the input. Relegation by inputs implies assigning the control of trajectories and forces to independent groups of inputs. In this paper, exact and approximate input relegation strategies are investigated. The effectiveness of the input relegation strategy is tested by digital computer simulation of a three link planar robot in a periodic rubbing maneuver.

scholarly journals Direct Adaptive Tracking Control for a Class of Pure-Feedback Stochastic Nonlinear Systems Based on Fuzzy-Approximation

2014 ◽  
Vol 2014 ◽  
pp. 1-10
Author(s):  
Huanqing Wang ◽  
Xiaoping Liu ◽  
Qi Zhou ◽  
Hamid Reza Karimi
Keyword(s):  
Nonlinear Systems ◽  
Tracking Control ◽  
Controller Design ◽  
Tracking Error ◽  
Small Neighborhood ◽  
Adaptive Controller ◽  
Stochastic Nonlinear Systems ◽  
Fuzzy Logic Systems ◽  
Adaptive Tracking Control ◽  
Adaptive Tracking

The problem of fuzzy-based direct adaptive tracking control is considered for a class of pure-feedback stochastic nonlinear systems. During the controller design, fuzzy logic systems are used to approximate the packaged unknown nonlinearities, and then a novel direct adaptive controller is constructed via backstepping technique. It is shown that the proposed controller guarantees that all the signals in the closed-loop system are bounded in probability and the tracking error eventually converges to a small neighborhood around the origin in the sense of mean quartic value. The main advantages lie in that the proposed controller structure is simpler and only one adaptive parameter needs to be updated online. Simulation results are used to illustrate the effectiveness of the proposed approach.

scholarly journals Zero Average Dynamic Controller for Speed Control of DC Motor

2021 ◽  
Vol 11 (12) ◽  
pp. 5608
Author(s):  
Fredy E. Hoyos ◽  
John E. Candelo-Becerra ◽  
Alejandro Rincón
Keyword(s):  
Direct Current ◽  
Control Strategy ◽  
Power Supply ◽  
Tracking Error ◽  
Reference Signal ◽  
Dc Motor ◽  
Buck Converter ◽  
Speed Tracking ◽  
Direct Current Motor ◽  
Simulation Results

This paper presents the use of the buck converter with Zero Average Dynamics to control the speed of a permanent magnet direct current motor. For this objective, we consider a fourth-order nonlinear model that describes the system’s dynamics and tests different scenarios to determine how the direct current motor responds. The results show a robust speed tracking performance of the direct current motor under the reference signal and controller parameter changes and disturbances in the load torque. A non-saturated duty cycle with fixed commutation frequency is obtained in the power supply of the DC motor, and a low steady-state value of the speed tracking error is achieved in both experimental and simulation results. In summary, the effectiveness of the Zero Average Dynamics control strategy for high order systems was experimentally proved.

Satellite formation keeping using differential lift and drag under J2 perturbation

2017 ◽  
Vol 89 (1) ◽  
pp. 11-19 ◽  
Author(s):  
Xiaowei Shao ◽  
Mingxuan Song ◽  
Jihe Wang ◽  
Dexin Zhang ◽  
Junli Chen
Keyword(s):  
Control Strategy ◽  
Tracking Error ◽  
Flat Plates ◽  
Satellite Formation ◽  
Content Type ◽  
Small Satellites ◽  
J2 Perturbation ◽  
Simulation Results ◽  
Lift And Drag ◽  
Formation Keeping

Purpose The purpose of this paper is to present a method to achieve small satellite formation keeping operations by using the differential lift and drag to control the drift caused by J2 perturbation in circular or near-circular low earth orbits (LEOs). Design/methodology/approach Each spacecraft is equipped with five large flat plates, which can be controlled to generate differential accelerations. The aerodynamic lift and drag acting on a flat plate is calculated by the kinetic theory. To maintain the formation within tracking error bounds in the presence of J2 perturbation, a nonlinear Lyapunov-based feedback control law is designed. Findings Simulation results demonstrate that the proposed method is efficient for the satellite formation keeping and better accuracy advantage in comparison with classical approaches via the fixed maximum differential aerodynamic acceleration. Research limitations/implications Because the aerodynamic force will reduce drastically as the orbital altitude increases, the formation keeping control strategy for small satellites presented in this paper should be limited to the scenarios when satellites are in LEO. Practical implications The formation keeping control method in this paper can be applied to solve satellite formation keeping problem for small satellites in LEO. Originality/value This paper proposes a Lyapunov control strategy for satellite formation keeping considering both lift and drag forces, and simulation results show better performance with high accuracy under J2 perturbation.

Performance comparison of electric-vehicle drivetrain architectures from a vehicle dynamics perspective

2019 ◽  
Vol 234 (4) ◽  
pp. 915-935
Author(s):  
Kerem Bayar
Keyword(s):  
Electric Vehicle ◽  
Control Strategy ◽  
Vehicle Dynamics ◽  
Tracking Control ◽  
Tracking Error ◽  
Vehicle Stability ◽  
Electric Motors ◽  
Sideslip Angle ◽  
Stopping Distance ◽  
Braking System

Recent electric vehicle studies in literature utilize electric motors within an anti-lock braking system, traction-control system, and/or vehicle-stability controller scheme. Electric motors are used as hub motors, on-board motors, or axle motors prior to the differential. This has led to the need for comparing these different drivetrain architectures with each other from a vehicle dynamics standpoint. With this background in place, using MATLAB simulations, these three drivetrain architectures are compared with each other in this study. In anti-lock braking system and vehicle-stability controller simulations, different control approaches are utilized to blend the electric motor torque with hydraulic brake torque; motor ABS, torque decomposition, and optimal slip-tracking control strategies. The results for the anti-lock braking system simulations can be summarized as follows: (1) Motor ABS strategy improves the stopping distance compared to the standard anti-lock braking system. (2) In case the motors are not solely capable of providing the required braking torque, torque decomposition strategy becomes a good solution. (3) Optimal slip-tracking control strategy improves the stopping distance remarkably compared to the standard anti-lock braking system, motor anti-lock braking system, and torque decomposition strategies for all architectures. The vehicle-stability controller simulation results can be summarized as follows: (1) higher affective wheel inertia of the on-board and hub motor architecture dictates a higher need of wheel torque in order to generate the tire force required for the desired yaw rate tracking. A higher level of torque causes a higher level of tire slip. (2) Optimal slip-tracking control strategy reduces the tire slip trends drastically and distributes the traction/braking action to each tire with the control-allocation algorithm specifying the reference slip values. This reduces reference tire slip-tracking error and reduces vehicle sideslip angle. (3) Tire slip trends are lower with the hub motor architecture, compared to the other architectures, due to more precise slip control.

Implementation of non-linear tracking control schemes for a serial/parallel topology robot

1997 ◽  
Vol 211 (6) ◽  
pp. 457-470
Author(s):  
L Yao ◽  
S K Spurgeon
Keyword(s):  
Motion Control ◽  
Control Strategy ◽  
Tracking Control ◽  
Experimental Studies ◽  
Joint Motion ◽  
Linear Controller ◽  
Control Schemes ◽  
Non Linear ◽  
Simulation Results ◽  
Three Degree Of Freedom

Results of the application of an advanced non-linear controller to the problem of joint motion control for a robot are presented. For a class of desired state motions a control strategy is expounded which ensures that the system asymptotically tracks the desired motion to any desired degree of accuracy. The results are applied to a three-degree-of-freedom tetrahedral robot. Simulation results and experimental studies are described.

ZMP Tracking Control of an Android Robot Leg on Slope-Changing Ground Using Disturbance Observer and Dual Plant Models

2016 ◽  
Vol 13 (03) ◽  
pp. 1550043 ◽  
Author(s):  
Jung-Yup Kim ◽  
Young-Seog Kim
Keyword(s):  
Control Strategy ◽  
Tracking Control ◽  
Disturbance Observer ◽  
Balance Control ◽  
Control Strategies ◽  
Center Of Mass ◽  
Model Inversion ◽  
Slope Change ◽  
Ground Slope ◽  
Android Robot

This paper describes a novel zero moment point (ZMP) tracking control strategy using a disturbance observer (DOB) in the presence of ground slope change for balance control of an android robot. With regard to conventional ZMP controls, many researchers have studied ZMP tracking control strategies using an inverted pendulum model on flat level ground, and they have solved a slow response problem of nonminimum phase systems by using suitable feedforward motions called walking patterns. However, the conventional methods lead to ZMP offset errors in the presence of ground slope change; it is hence necessary to quickly eliminate the ZMP offset errors to realize robust balance control. In this paper, we rapidly eliminate the ZMP offset errors through a DOB using a model inversion for robust balance control in the presence of ground slope change. In particular, a dynamic model that uses the projected center of mass (CoM) position on the ground is additionally used as an output to solve a problem that generates an unstable pole during model inversion. Finally, the proposed control strategy is verified through MATLAB simulations and experiments using a real android leg.

Disturbance observer based dynamic surface flight control for an uncertain aircraft

2017 ◽  
Vol 232 (4) ◽  
pp. 729-744 ◽  
Author(s):  
Jianjun Ma ◽  
Peng Li ◽  
Zhiqiang Zheng
Keyword(s):  
Flight Control ◽  
Disturbance Observer ◽  
Sliding Mode ◽  
Tracking Error ◽  
Small Neighborhood ◽  
Dynamic Surface ◽  
Nonlinear Disturbance Observer ◽  
Actuator Dynamics ◽  
Highly Nonlinear ◽  
Nonlinear Disturbance

To handle the flight control problem of an uncertain aircraft with highly nonlinear characteristics, internal uncertainties and external disturbances, an adaptive dynamic surface controller based on nonlinear disturbance observer is designed in this paper. A novel nonhomogeneous nonlinear disturbance observer is designed to approximate the uncertainties and disturbances, which can exactly estimate the disturbances in finite time. Dynamic surface control is utilized to avoid the explosion of complexity in traditional backstepping design. Through Lyapunov synthesis, the closed-loop control system is demonstrated to be semi-globally uniformly ultimately bounded and the tracking error converges to a small neighborhood of origin. Besides, actuator dynamics are taken into account, and the controller for actuator dynamics with consideration of limitation is developed based on sliding-mode control theory. The effectiveness of the proposed control is shown by simulation experiments.

The least-time optimization for abnormity control of a complex industrial process

2018 ◽  
Vol 41 (5) ◽  
pp. 1468-1476
Author(s):  
Hui Li ◽  
Fuli Wang ◽  
Hongru Li ◽  
Xu Wang
Keyword(s):  
Control Problem ◽  
Control Strategy ◽  
Optimization Problem ◽  
External Environment ◽  
Industrial Process ◽  
Economic Loss ◽  
Industrial Processes ◽  
Mechanical Constraints ◽  
Time Optimization ◽  
Simulation Results

Modern complex industrial processes are prone to errors because of interactions between humans, the external environment and the equipment. When the abnormity degree of a system increases, the system can generate failures or even accidents, which result in serious economic loss or even personal casualties. Therefore, it is necessary to take effective measures to remove the abnormity as soon as possible. This problem can be described as the least-time optimization problem. This paper analyses an abnormity by summarizing and comparing related concepts in the researched results. Based on these concepts, a control strategy for the abnormity in a complex industrial process is proposed by analysing the experience of operators on site. Taking the abnormity in the thickening process of gold hydrometallurgy as an example, this paper explores how the abnormity control problem can be transformed into the least-time optimization problem. Technical and mechanical constraints are described. Simulation results indicate that the proposed strategy can assist the operators to regulate the control variables and recover the abnormity as soon as possible. This produces better performance than the existing regulations on site.

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