Terminal Sliding‐Mode Control of Uncertain Robotic Manipulator System with Predefined Convergence Time

Abstract

This paper concentrates on the predefined-time trajectory tracking for an uncertain robotic manipulator system. First, a modified predefined-time control (PTC) algorithm is proposed. Subsequently, with the help of proposed modified PTC algorithm and the nonsingular design method of terminal sliding mode, a novel nonsingular terminal sliding-mode control (NTSMC) scheme is proposed for ensuring the predefined-time convergence of tracking errors. The advantages of the newly proposed control scheme are as follows. (i) Unlike the conventional predefined-time sliding-mode control (SMC) which only guarantees the predefined-time convergence of sliding-mode surface, the proposed scheme can guarantee the predefined-time convergence of tracking errors. (ii) Compared with the conventional PTC algorithm, the proposed modified PTC algorithm can reduce the initial control peaking and enhance the precision of convergence time. The performance and effectiveness of the proposed control scheme are illustrated by comparing with the existing methods.

A Robust Adaptive Non-Singular Terminal Sliding Mode Control: Application to an Upper-Limb Exoskeleton with Disturbances and Uncertain Dynamics

“…Various approaches have been explored to alleviate the high-frequency switching problem in sliding mode control systems. The authors in [10] opted for the saturation function (sat) instead of the signum function (sign), while the authors in [34,36,38] employed high-order sliding mode controllers, introduced non-ideal sliding surfaces, utilized smooth control inputs, and designed a boundary layer control law.…”

“…Nevertheless, TSMC suffers from a singularity problem, prompting the development of fast terminal sliding mode control (FTSMC) as an extension of TSMC, which achieves higher convergence rates and stronger robustness despite significant initial system errors. FTSMC utilizes a modified terminal sliding surface that facilitates faster convergence of the system's states [34,36,37].…”

“…According to the ensure that the de Lemma 1: Cons definite function (34) Inserting the expression of the control law (30) for S δ ≥ into Equation (34) gives:…”

Sliding mode controller design for unstable processes with dead time with a case study on continuous stirred tank reactor

“…The control parameters obtained through the proposed technique by minimizing the objective functions stated in equations (19), (26)…”

“…With these properties, sliding mode control (SMC) is widely used in various applications, like the chemical industry [7][8][9][10], process control [11][12][13], power system [14] and biomedical processing [15]. Recently, some modified SMCs such as fixed-time terminal SMC (TSMC) [16][17][18] and predefined-time TSMC [19], are used in robotics control.…”