Adaptive backstepping sliding mode control based on nonlinear disturbance observer for trajectory tracking of robotic manipulator

This paper proposes and analyzes two different control techniques to remove the effect of lumped uncertainties and disturbances for trajectory tracking by robotic manipulator. These techniques are a) Adaptive backstepping sliding mode control and b) Nonlinear disturbance observer based backstepping sliding mode control. Adaptive backstepping sliding mode control estimates the system uncertainties and disturbance using an adaptive law. Lyapunov theory is used to define the adaptive law for the convergence of tracking error. The second technique initially estimates the unknown external disturbances using non-linear disturbance observer and then generates control input using beckstepping sliding mode controller. Backstepping sliding mode ensures the sliding surface to be chattering free and improves convergence rate in finite-time. The stability of system is analyzed using Lyapunov theory for both the techniques. Simulation results show the effectiveness and robustness of proposed techniques FOR trajectory tracking.