Reachable Sets for Safe, Real-Time Manipulator Trajectory Design
Patrick Holmes, Shreyas Kousik, Bohao Zhang, Daphna Raz, Corina Barbălată, Matthew Johnson‐Roberson, Ram Vasudevan · 2020
For robotic arms to operate in arbitrary environments, especially near people, it is critical to certify the safety of their motion planning algorithms.However, there is often a trade-o↵ between safety and real-time performance; one can either carefully design safe plans, or rapidly generate potentiallyunsafe plans.This work presents a receding-horizon, real-time trajectory planner with safety guarantees, called ARMTD (Autonomous Reachability-based Manipulator Trajectory Design).The method first computes (o✏ine) a reachable set of parameterized trajectories for each joint of an arm.Each trajectory includes a fail-safe maneuver (braking to a stop).At runtime, in each receding-horizon planning iteration, ARMTD constructs a parameterized reachable set of the full arm in workspace and intersects it with obstacles to generate sub-di↵erentiable, provablyconservative collision-avoidance constraints on the trajectory parameters.ARMTD then performs trajectory optimization over the parameters, subject to these constraints.On a 6 degree-of-freedom arm, ARMTD outperforms CHOMP in simulation, never crashes, and completes a variety of real-time planning tasks on hardware.