A Planning Framework for Complex Flipping Manipulation of Multiple Mobile Manipulators

During complex object manipulation, manipulator systems often face the configuration disconnectivity problem due to closed-chain constraints. Although regrasping can be adopted to guarantee connectivity, it introduces additional issues such as impact and efficiency. Therefore, regrasping numbers should be minimized during manipulation. To address this problem, a novel planning framework is proposed for multiple mobile manipulator systems. Given the object trajectory and the grasping pose set, the planning framework includes three steps. First, the inverse kinematic solution is verified along the given trajectory based on different grasping poses. Coverable trajectory segments are determined for each robot for a specific grasping pose. Second, the trajectory choice problem is formulated into a set cover problem, by which we can quickly determine whether the manipulation can be completed without regrasping or with a minimal regrasping number. Finally, the motions of each mobile manipulator are planned with the assigned trajectory segments using existing methods. Both simulations and experimental results show the performance of the planner in complex flipping manipulation. Additionally, theoretical analysis and multiple simulations are conducted to demonstrate the performance of the planner.