Robust fixed-time cooperative control strategy design for nonlinear multiple-master/multiple-slave teleoperation system

Abstract

In this paper, a fixed-time cooperative control problem for a class of multiple-master/multiple-slave (MMMS) teleoperation systems with external disturbances and internal system uncertainties is addressed. The MMMS teleoperation system has many potential applications due to its obvious structure advantages such as powerful environmental applicability, excellent load capacity, flexible collaboration and so on. Meanwhile, considering a large amount of data transmission, various uncertainties and collaborative coupling among the multiple operators and multiple manipulators, it is challenging to design a control strategy for the MMMS teleoperation system to achieve satisfactory control performance. To solve these issues, a novel robust fixed-time control strategy 15 is proposed for the uncertain MMMS teleoperation system. At first, a new virtual master-slave control framework for the MMMS system is constructed, which enhances the transparency of the system and makes system stability analysis easier. Then, new fixed-time disturbance observers (DOs) are designed separately for the master and the slave sides to accurately estimate the internal uncertainties and external disturbances under a more realistic assumption. Moreover, a new multi-dimension nonsingular sliding mode (SM) surface is presented, on which the states of the system can tend to the desired equilibrium in fixed time not affected by the initial state values. The cooperative control strategy based on the new DO and SM surface can not only ensure the fixed-time stability of the system, but also improve the system robustness to the external disturbances and internal uncertainties. In the end, simulations are performed to prove the validity of the theoretical results.