Adaptive Integral-Type Terminal Sliding Mode Tracker Based on Active Disturbance Rejection for Uncertain Nonlinear Robotic Systems With Input Saturation

Abstract

This paper proposes an adaptive integral-type terminal sliding mode tracking control approach based on the active disturbance rejection for uncertain nonlinear systems subject to input saturation and external disturbances. Its main objective is to achieve zero tracking error in the presence of external disturbances, parametric uncertainties and input saturation; ubiquitous problems in most practical engineering systems. The proposed approach combines the robustness and chattering-free dynamics of adaptive integraltype sliding mode control with the estimation properties of a nonlinear extended state observer. It also assumes the bounds of the input saturation to be unknown. The asymptotic stability of the closed-loop system in the presence of disturbances, uncertainties and input saturation is proven using the Lyapunov theorem. The effectiveness of the proposed approach is assessed using a flexible-link robotic manipulator. The obtained results confirmed the robustness and god tracking performance of the proposed approach. Robustness, chattering-free dynamics and good tracking performance albeit input saturation are among the main features INDEX TERMS Active disturbance rejection; nonlinear system; terminal sliding mode control; input saturation; flexible-link manipulator.

Non-Negative Adaptive Mechanism-Based Sliding Mode Control for Parallel Manipulators with Uncertainties

“…Compared with state-of-the-art approaches [13][14][15][16][17][18][19][20][21][22][23][24][25][26], the proposed approach does not require the upper bound of uncertainties, which is almost impossible to obtain in many real applications. Besides, the proposed control scheme has superior tracking control performance such as convergence fast to the finite-time stable equilibrium, the non-singularity, rapid response, and the strong robustness with complex uncertainties and external disturbances.…”

“…However, NTSMC or FTSMC has just only resolved one problem and neglected the other aspects of TSMC. To cope with both singular problems and slow convergence speed, integral terminal sliding mode control (ITSMC) [19,20] and nonsingular fast terminal sliding mode control (NFTSMC) [21][22][23][24][25][26] are developed. However, ITSMC is designed based on TSMC, and then, the above feebleness of TSMC may still exist.…”

“…Among them, the saturation method is widely used in implementation because it provides both chattering elimination and high accuracy. Generally, the corresponding suitable approaches [15][16][17][18][19][20][21][22][23][24][25][26][27][28] can overcome some drawbacks of TSMC. However, none of these approaches can resolve all of the problems of TSMC simultaneously.…”

“…1) The online non-negative adaptive mechanism (NAM) is used to estimate the uncertainties and disturbances. Hence, unlike the existing TSMC [13][14][15][16][17][18][19][20][21][22][23][24][25][26], the proposed approach does not require prior knowledge about the bounds of the complexity of external disturbances and complex uncertainties.…”

Development of Sliding Mode Controller Based on Internal Model Controller for Higher Precision Electro-Optical Tracking System

“…For nonlinear systems with external disturbances, Alattas et al [22] suggested an adaptive non-singular fast terminal SMC with integral surface and a novel adaptive rate to relieve the chattering problem. Karami et al [23] proposed an adaptive integral terminal SMC approach for uncertain nonlinear systems subject to input saturation and external disturbance by integrating adaptive integral SMC with nonlinear extended-state observer. This strategy substantially reduces the chattering effect while also eliminating uncertainties.…”