Safety control of robots under Computed Torque control using reachable sets

Abstract

A failsafe control strategy is presented for online safety certification of robot movements in a collaborative workspace with humans. This approach plans, predicts and uses formal guarantees on reachable sets of a robot arm and a human obstacle to verify the safety and feasibility of a trajectory in real time. The robots considered are serial link robots under Computed Torque schemes of control. We drastically reduce the computation time of our novel verification procedure through precomputation of non-linear terms and use of interval arithmetic, as well as representation of reachable sets by zonotopes, which scale easily to high dimensions and are easy to convert between joint space and Cartesian space. The approach is implemented in a simulation, to show that real time is computationally within reach.