Adaptive variable structure controller of redundant robots with mobile/fixed obstacles avoidance

• Adaptive controller without knowledge of the dynamical model of the robot.
• The stability is proved theoretically using the Lyapunov principle.
• The controller is designed directly in the task space.
• No inversion of models is required.
• No collision with moving obstacles is possible.

In this paper, a variable structure adaptive controller is proposed for redundant robot manipulators constrained by moving obstacles. The main objective of the controller is to force the model states of the robot to track those of a chosen reference model. In addition, the controller is designed directly in Cartesian space and no knowledge on the dynamic model is needed, except its structure. The parameters of the controller are adapted using adaptive laws obtained via Lyapunov stability analysis of the closed loop. The performances of the proposed controller are evaluated using a 3 DOF robot manipulator evolving in a vertical plane constrained by a mobile obstacle. The obtained results show its effectiveness compared to other tested variable structure controllers.