Calculating human reachable occupancy for guaranteed collision-free planning

Abstract

We address the problem of overapproximative short-term prediction of arm movement, for safe human-robot co-existence. A trajectory planner for a robot manipulator which formally verifies non-collision requires fast prediction of human future occupancy, which must be accurate yet still account for all possible human movement. This work presents two approaches to this: a novel, simple approach calculated directly in task space, and another approach using a kinematic model of the human based on the authors' previous work. We compare both approaches in an experimental setup with a robot manipulator. To the best of our knowledge, this is the first implementation and comparison of approaches to formally verified trajectory planning in human-robot co-working. We find that the novel approach has advantages in terms of ease and speed of computation and tightness at short time horizons and is more intuitive to extend to the whole human body; the previous approach offers advantages at longer prediction horizons. We also perform conformance checking to show that both approaches do indeed account for all relevant movement.