Stable grasp planning by evolutionary programming

Abstract

This paper deals with the problem of synthesis of stable grasp by multifingered hands. First, a mathematical description of the problem is formulated. The grasp to be synthesized should satisfy equilibrium conditions and unilateral frictional constraints. In addition, it should be stable against disturbances applied to the object. Two types of stability conditions, contact stability and Lyapunov stability, are taken into consideration. Contact points, contact forces and joint stiffnesses are considered as the problem variables. The objective function maximizes admissible linear and rotational disturbances applied to the object, Since the dimension and the complexity of the resulting constrained optimization problem is high enough, the evolutionary programming (EP) approach is explored. Two EP techniques, a conventional one and a specially designed robust technique with a genetic drift, are discussed. The feasibility of these techniques is verified for the synthesis of stable grasp by a three-fingered robotic hand.