EXPONENTIAL REACHING LAW-BASED SLIDING MODE CONTROL FOR A 2-DOF PLANAR ROBOT: ROBUSTNESS TO DISTURBANCES AND MASS VARIATIONS

Abstract

This paper presents a robust sliding mode control (SMC) strategy based on an exponential reaching law for a two-degrees-of-freedom (2-DoF) planar robotic manipulator. The proposed controller is designed to achieve fast and accurate convergence of tracking errors while mitigating the chattering effects typically associated with conventional SMC approaches. By incorporating an exponentially decaying term into the reaching law, the controller enhances the smoothness of the sliding motion and improves the transient performance of the system. The dynamic model of the robotic manipulator is derived using the Euler–Lagrange formulation to capture the system's nonlinear and coupled dynamics. A Lyapunov-based stability analysis is employed to establish the asymptotic stability of the closed-loop system. To evaluate the controller’s effectiveness, extensive simulation studies are conducted under various scenarios, including nominal conditions, the presence of external disturbances, and significant variations in link mass parameters. The simulation results confirm excellent trajectory tracking performance and strong robustness, thereby demonstrating the controller’s adaptability to both ideal and uncertain environments. These results underline the potential of the proposed control scheme for practical applications in advanced robotic systems