Data-driven observer-based model-free adaptive discrete-time terminal sliding mode control of rigid robot manipulators

This paper aims to design a data-driven observer-based model-free adaptive terminal sliding mode controller for rigid robot manipulators whose models are unknown in advance. First, the nonlinear robot manipulator dynamics are transformed to an equivalent linear discrete-time data-model using full-form dynamic linearization technique and multi-observers along with an adaptation law are designed in order to estimate system outputs and pseudo-partitioned Jacobian matrix, respectively. Second, based on a nonlinear data-driven terminal sliding surface, the robust discrete-time controller is obtained. Mathematical analysis guarantees the finite-time convergence and the stability of the closed-loop system. The comparative simulations lighten the superiority of the proposed work and the robustness of the proposed controller against external disturbances is validated by means of simulations.

I. Introduction

Robot manipulators have a special place in industrial processes and therefore, precise motion control of them has attracted researchers' attention in the last decades. Due to the complex and nonlinear dynamics of the robot manipulators, several kinds of controllers have been employed. Some examples are robust controllers [1]–[5], intelligent controllers [6], [7] and etc.