Controller Based on Null Space and Sliding Mode (NSB-SMC) for Bidirectional Teleoperation of Mobile Robots Formation in an Environment with Obstacles

This work presents a control approach for the problem of formation of mobile robots based on null spaces and sliding mode (NSB-SMC), using a bidirectional teleoperation with force feedback with a haptic device in a semi-structured environment with static and dynamic obstacles. The NSB-SMC algorithm includes a sliding mode control scheme (SMC) to improve robustness with respect to a null space-based controller with a type PID (NSB-PID). The tasks to achieve are to maintain the formation, posture and at the same time the avoidance of obstacles within a formation of mobile robots. The algorithm of static and dynamic obstacle avoidance base on the method of potential fields; and force feedback for the human operator is performed through a Gaussian zone that generates a force of repulsion in the presence of obstacles. Moreover, a haptic device allows interpreting the intention of the user applying the criterion of mechanical impedance. General control system stability is analyzed through the Lyapunov theory. Finally, the novel NSB-SMC algorithm and the NSB-PID controller are compared, demonstrating better performance in the proposed scheme.