Non-Prehensile Whole-Arm Manipulation Grasping and Trajectory Generation in 3D

For manipulating large, bulky loads, whole-arm manipulation is a suitable method. It is often used in a non-prehensile way. However, non-prehensile manipulation is mostly considered only two-dimensional, for example, moving an object on a surface. Whole-arm manipulation, on the other hand, often requires 3-dimensional movements. If redundant manipulators are used for whole-arm manipulation, there may be several valid poses for a way-point on a trajectory but only one of these configurations allows to cover the largest possible distance on the trajectory without reconfiguration. Reconfiguration is not possible with whole-arm manipulation, as this would result in a loss of the object. Numerical methods, on the contrary, can only randomly select one of these configurations. Therefore, we propose a completely analytical trajectory generation method for moving cylindrical bodies, which allows exploration of the entire path for optimal robot configuration and redundancy resolution. The contact plane along the longitudinal axis of the cylinder can be passed as an allowed interval and is used by the algorithm for optimization. In experiments, we compare our method against RRTConnect and the impact of the shiftability of the contact plane on the performance of our method. The results show that the proposed method finds up to two and a half times longer distances than RRTConnect on a path without reconfiguration, but takes more time to do so. Finally, we demonstrate the applicability in a real-world scenario in nursing.