Second order sliding mode motion control of rigid robot manipulators

This paper presents a control strategy for robot manipulators, based on the coupling of the inverse dynamics method with the so-called second order sliding mode control approach. The motivation for using sliding mode control in robotics mainly relies on its appreciable features, such as design simplicity and robustness. Yet, the chattering effect, typical of the conventional sliding mode control, can be destructive. In this paper, this problem is suitably circumvented by adopting a second order sliding mode control approach characterized by a continuous control law. To design the inverse dynamics part of the proposed controller, a suitable dynamical model of the system has been formulated, and its parameters have been accurately identified. The proposed inverse dynamics-based second order sliding mode controller has been experimentally tested on a COMAU SMART3-S2 industrial manipulator, demonstrating the tracking properties and the good performances of the controlled system.