Hybrid impedance control of robotic manipulator using adaptive backstepping sliding mode controller with PID sliding surface

Abstract

In this paper, a hybrid impedance controller for a multi degrees of freedom (DoF) robot manipulator is developed using the backstepping sliding mode algorithm. Unlike the existing hybrid control method using sliding mode, backstepping is used in this paper to obtain a proportional-integral-derivative (PID) sliding surface. The PID sliding surface corresponds to the desired impedance dynamics of the manipulator both during free space and constraint space motion when the end-effector is in contact with the environment. The sliding gain of the controller is tuned adaptively to reduce the chattering and thereby limiting the usage of excessive control energy. A varying stiffness is used along the force controlled direction to improve the force tracking performance. Simulation results validate applicability of the proposed controller for multi DoF robot manipulators.