Designing sliding mode control using exponential functions applied for the 5-DOF VNR T1 robot

Abstract

Sliding mode control (SMC) has been studied and applied in various industrial systems due to its robustness and wide applicability. The drawback of conventional SMC is that the chattering phenomenon exists in the system caused by the control signal having discontinuous component. Therefore we have to accept a long system’s transient time to receive a small chattering level. Commonly, the chattering problem can be overcome by using a saturation function or some other functions instead of the signum function. In order to create a large control signal during reaching phase and maintain a small control value during the sliding phase, the paper presents a SMC which uses an exponential function in the switching law. Hence, the system can catch up the sliding surface quickly and to reduce the total settling time. While the system going on the sliding manifold, the reaching part of the control law preserves a small enough value such that it almost does not make the chattering degree in the sliding phase. The proposed SMC is applied to the 5-DOF VNR T1 robot. Simulation results performed on the quasi-physical robot model using MATLAB/Simscape Multibody reflect the effectiveness of this approach