Research On Contact Kinematics Of Higher Pairs With Point Contact Surfaces And Application In Multi-Fingered Grasps

The kinematics of higher pairs with point contact surfaces and the application on manipulation of multifingered robot hand are researched in this paper. The kinematic equations of point contact is derived based on rigid-body three-dimensional kinematics and differential geometry, and then the contact equations are classified into three relative motions: sliding contact, rolling contact and general contact with sliding and rolling. Forward and inverse problems of displacement are defined and their formulas are derived. The relationship of contact trajectories on two rigid bodies with rolling contact is described.The theories and methods of nonlinear control systems are applied to kinematic control of spatial higher pairs with point contact surfaces. The relative velocity between contacts is defined as input, and the contact equations are looked upon as the representation of a driftless nonlinear control system. The conditions for the motion between the current contact configuration and the desired configuration are given by controllability of the driftless nonlinear control system. Multinomial inputs are used for steering into the systems from the current contact configuration to the desired configuration. The sliding mode control is applied to a desired trajectory tracking in the contact configuration.The theories on surface point contact higher pairs are applied to analyzing grasp and manipulation of multifingered robot hand with point contact. The kinematic equations representing object motion and finger motion are established. The joint angles of finger and the contact points on the surfaces of the finger tip and the object can be computed with the equations and constrains.