Robust Passivity-based Sliding Mode Control of a Large Class of Nonlinear Systems Subject to Unmatched Uncertainties: A Robot Manipulator Case Study

Abstract

The existence of unmatched uncertainties is known as a serious challenge for designing a robust sliding mode control (SMC) law for nonlinear systems. To pass over this obstacle, a novel robust passivity-based sliding mode approach is proposed here for a large class of MIMO nonlinear systems. The design procedure is accomplished in two steps in presence of both matched and unmatched uncertainties. First, an efficient adaptive sliding surface is designed based on the passivity concept. The passivity provides a flexible robust structure for the sliding surface and guarantees the global asymptotic stability of the reduced-order equations of the system as well. Furthermore, simple adaptation laws are obtained to eliminate the effects of uncertainties. Then, the robust controller is formulated using the SMC method. As another important advantage, the proposed approach is relaxed from the upper bound’s constraints of the uncertainties. It is also applied to n-link rigid electrically driven robot manipulator as a widely-used practical nonlinear system. The simulation results show the appropriate tracking performance for the industrial selective compliance assembly robot arm (SCARA) in the presence of noisy external disturbances. Also, an extending case is studied with related research to emphasize the potential of the proposed approach.

KEYWORDS:

• Unmatched uncertainties
• Robust passivity-based control
• Sliding mode control
• Adaptive sliding surface
• SCARA robot
• Asymptotic stability
• Electrically driven robot manipulator

Additional information

Notes on contributors

Hamed Chenarani

Hamed Chenarani received his BSc degree in communication engineering from Shahid Bahonar University of Kerman in 2012 and his MSc degree in control engineering from Shiraz University of Technology in 2014. Currently, he is a PhD candidate for the Electrical Engineering Department of Shahrrod University of Technology. His research interests include robust nonlinear control, passive control, robotics, and intelligent control. Currently, he is working on robust nonlinear control of Robot Manipulators.

Mohammad Mehdi Fateh

Mohammad Mehdi Fateh received his BSc degree from Isfahan University of Technology, in 1988 and his MSc degree in electrical engineering from Tarbiat Modares University, Iran, in 1991. He received his PhD degree in robotic engineering from Southampton University, UK, in 2001. He is a full professor with the Department of Electrical Engineering at University of Shahrood. His research interests include robust nonlinear control, fuzzy control, robotics and intelligent systems, mechatronics and automation.Email: [email protected]