Motion Planning for Smooth Pickup of Moving Objects

Abstract

Kinematic planning for robotic arms has been shown to be capable of planning for robust manipulation of static objects. However, this approach falls short when manipulating moving objects such as picking up a jar off of a conveyor belt at a bottling plant. The challenge in carefully picking up moving objects is that these actions require motions that do not involve large decelerations, to avoid jerking the object, as well as figuring out the proper time in which the object can be picked up. We present a search-based kinodynamic motion planning algorithm that generates a time-parameterized trajectory for both the arm and end-effector, capable of carefully picking up the object at the earliest feasible point in its trajectory. To combat the high-dimensionality of the time-parameterized kinodynamic planning problem, our approach employs informative heuristics and adaptive dynamic motion primitives. To validate our approach, we used a 7DOF manipulator on Willow Garage's PR2 robot to pickup objects off of a conveyor belt. We also provide a detailed set of results that demonstrate the planner's ability to generate consistent, low cost trajectories for manipulation.