Planning of Graspless Manipulation by Multiple Robot Fingers

Graspless manipulation is to manipulate objects without grasping by just pushing, tumbling, and so on. One of the main difficulties in graspless manipulation is planning. It is very time-consuming to plan a general graspless manipulation problem, because it requires complicated mechanical analysis including friction. To reduce the load of computation, we adopt a two-step approach: 1) construction and simplification of contact state graph at geometry level, and 2) planning of manipulation at mechanics level. In this paper, we focus the latter, and propose an algorithm to plan mechanically feasible manipulation. It generates digraphs that represent C-Subspaces for all the contact states, and unites them into one big graph, which we call “manipulation-feasibility graph.” Manipulation plan can be obtained by searching the graph. This algorithm is implemented for planar graspless manipulation by multiple robot fingers, and planned results are shown.