Robotic handwriting: Multi-contact manipulation based on Reactional Internal Contact Hypothesis

When one uses a hand-held tool, the fingers often make the tool to be in contact with the palm in the form of multi-contact manipulation. Multi-contact manipulation is useful for object-environment interaction tasks because it can provide both powerful grasping of the object body and dexterous manipulation of the object end-effector. However, dealing with the internal link contact with the object is not trivial. In this paper, we propose Reactional Internal Contact Hypothesis that regards the internal contact force as a reaction force so that the desired finger force can be reduced. By taking a handwriting task as an example, optimal configuration search and grasping force computation problems are addressed based on this hypothesis and validated via dynamic simulation.