SIMPLIFIED EXPONENTIAL REACHING LAW BASED SLIDING MODE CONTROL OF TWO-LINK PLANAR ROBOT

Abstract

Robotics has gained attention for its ability to perform industrial tasks like welding, machining, position con- trol, and other essential medical operations. Controllers are continuously being improved in design for simplicity, robustness, and performance accuracy. High-accuracy trajectory tracking is a challenging area in robot control due to nonlinearities and input couplings. To achieve high accuracy and precision, robots need accurate, and fast- processing controllers. This research focuses on applying the exponential reaching law (ERL) to control a two-link planar robot. The Euler-Lagrange approach was used for dynamic modeling, and the MATLAB/Simulink toolbox was used for the simulation. The result was obtained in terms of RMS error for the links, with and without the fric- tional disturbance, in the case of the proportional and derivative (PD) controller, reaching law based sliding mode controller (RSMC), and the simplified exponential reaching law based sliding mode controller (SSMC). RMSE with disturbance for SSMC (0.0753 rad, 0.0817 rad for link 1 and link 2 respectively), RSMC (0.0828 rad, 0.0852 rad) and PD (0.2784 rad, 0.1062 rad), and RMSE values without disturbance for SSMC (0.0743rad, 0.0811rad for link 1 and link 2 respectively), RSMC (0.0752 rad, 0.0815 rad) and PD (0.2579 rad, 0.1021 rad). Based on the result obtained, SSMC was found to be more accurate and robust as a result of having the minimum tracking error minimum change in RMSE respectively, as compared to the other controllers. It is evident that SSMC control scheme has proven to have an improved performance with simplicity and robustness.