Coordinated manipulation of objects by multifingered robotic hand in contact space and active joint space

Coordinated manipulation of objects by multifingered robotic hands aims to resolve the redundancy in object level and hand level, increase the rigidity and robustness of grasping, and achieve a good dynamic performance in trajectory control. In this paper, different from the usual ways used in most literatures about multifingered manipulation, a contact space approach and an active joint space approach axe explored. The former one, pulls back the dynamics of the object and fingers to contact space, establishes a dynamic equation naturally containing the internal force as the constraint force, resolves the redundancy in object level, and are suited for coordinated manipulation with fixed contact. The latter can, however, resolve the redundancy in hand level through deriving the dynamic model of the hand all in active joint space. The internal force in this case can still be interpreted as the constraint force in the active space. This model places the following problems associated with the coordinated manipulation with non-fixed contact into a unified framework: 1. sufficient conditions for the controllability of hand motion including both the velocity of contact coordinates and the object. 2. kinematic measure of robust grasp to generating the coordinated motion of contact coordinates. 3. searching a group of internal forces lying in the strict interior of the friction cone by LMI method. 4. hybrid control algorithms for simultaneous control of motion of hand and the internal grasping forces. 5. controlling the internal grasping force to ensure the total contact force lying in the friction cone. Experimental results done on HKUST hands are reported.