Adaptive Neural Output Feedback Control for Uncertain Robot Manipulators with Input Saturation

Abstract

This paper presents an adaptive neural output feedback control scheme for uncertain robot manipulators with input saturation using the radial basis function neural network (RBFNN) and disturbance observer. First, the RBFNN is used to approximate the system uncertainty, and the unknown approximation error of the RBFNN and the time-varying unknown external disturbance of robot manipulators are integrated as a compounded disturbance. Then, the state observer and the disturbance observer are proposed to estimate the unmeasured system state and the unknown compounded disturbance based on RBFNN. At the same time, the adaptation technique is employed to tackle the control input saturation problem. Utilizing the estimate outputs of the RBFNN, the state observer, and the disturbance observer, the adaptive neural output feedback control scheme is developed for robot manipulators using the backstepping technique. The convergence of all closed-loop signals is rigorously proved via Lyapunov analysis and the asymptotically convergent tracking error is obtained under the integrated effect of the system uncertainty, the unmeasured system state, the unknown external disturbance, and the input saturation. Finally, numerical simulation results are presented to illustrate the effectiveness of the proposed adaptive neural output feedback control scheme for uncertain robot manipulators.

Adaptive neural network fixed‐time control for an uncertain robot with input nonlinearity

“…These approaches, combining adaptive control and neural network approximation, have matured into powerful tools and have found widespread application. [34][35][36][37] In particular, the integration of neural network approximation methods into adaptive design, as seen in Reference 38, aims to eliminate feasibility conditions for barrier functions, enabling reliable tracking control.…”

LMI-Based Robust Stabilization of a Class of Input-Constrained Uncertain Nonlinear Systems with Application to a Helicopter Model

“…us, the neglect of the actuator constraints in the controller design may cause instability of the closed-loop system [17][18][19]. e design of controllers for continuous-time and discrete-time systems by taking into consideration the actuator saturation has been extensively studied in the past few decades [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36]. Some works have investigated the problem of uncertainties and actuator saturation in mechatronic systems such as the vehicle lateral dynamics [37], the vehicle active suspension systems [38][39][40][41], the rigid spacecraft [42,43], the inertia wheel inverted pendulum [12], the supercavitating vehicle [44], the flexible robotic manipulator [45], and the marine surface vessel [46], among others.…”

Nonlinear Dynamics Analysis and Global Stabilization of Underactuated Horizontal Spring-Coupled Two-Link Manipulator

“…With the improvement of industrial automation, the manipulators have been widely used in many areas of engineering [1][2][3][4]. For a manipulator, the damage of actuators is an inevitable problem caused by the wearing of devices and the influence of the surrounding environment.…”