Grasp strategies for a dextrous robotic hand

In the last two years, a dextrous hydraulic hand has been developed at the Lehrstuhl B fur Mechanik. As with all dextrous hands, in order to be able to manipulate objects effectively, the TUM Hand requires not only a sound construction and robust low-level control but also high level grasp planning. This paper discusses some of the high level grasp strategies used with the TUM Hand. The strategies presented have two main functions: the calculation of the grasp points and finger forces, and the positioning of the object within the hand. First, methods for calculating the grasp points and finger forces are presented. A decomposition of the finger forces into their normal and tangential, rather than internal and manipulation components is used. Once the grasp points and the finger forces are known, the problem of correctly placing the object within the hand can be considered. This paper describes the method used to locate and orient the hand relative to the object such that the fingers can reach their corresponding grasp points