Robust and Safe Coordination of Multiple Robotic Manipulators: An Approach Using Modified Avoidance Functions

This paper develops a strategy for collision avoidance among a system of robotic manipulators by using joint feedback controllers in the joint space, which have a closed form. The joint positions are directly used in computing the joint torques, without any additional intermediate steps for computing shortest distances or gradients of shortest distances between the links. Furthermore the collision avoidance controller can be augmented to any stable controller with different objectives, such as position tracking, velocity consensus etc. We consider set point stabilization as a control objective in this paper, and a Lyapunov based analysis is used to show convergence of the joints to their desired positions while guaranteeing collision avoidance among the links of the manipulators and avoiding deadlocks (unwanted local minima). The proposed control methodology is illustrated using some simulation and experimental results.