A certified-complete bimanual manipulation planner

Abstract

Planning motions for two robot arms to move an object collaboratively is a difficult problem, mainly because of the closed-chain constraint, which arises whenever two robot hands simultaneously grasp a single rigid object. In this paper, we propose a manipulation planning algorithm to bring an object from an initial stable placement (position and orientation of the object on a support surface) towards a goal stable placement. The key specificity of our algorithm is that it is certified-complete: for a given object and a given environment, we provide a certificate that the algorithm will find a solution to any bimanual manipulation query in that environment whenever one exists. Moreover, the certificate is constructive: at run-time, it can be used to quickly find a solution to a given query. The algorithm is tested in software and hardware on a number of large pieces of furniture. Note to Practitioners—This paper presents an algorithm to solve a difficult class of bimanual manipulation planning problems where a movable object can be moved only when grasped by two robots. This problem arises naturally when manipulating a large and/or heavy object such as a piece of furniture and is therefore essential to industrial automation. The algorithm first pre-computes a certificate, a set of robot motions to move the object between different placement classes that helps guarantee that the algorithm will find a solution to any planning query whenever one exists. This certificate is then used to quickly construct a solution trajectory to a planning query and can be reused under the same environment. The algorithm has been empirically verified through software and hardware experiments on a number of large pieces of furniture. An open-source implementation is provided.