Dimensional synthesis of a flexible gripper with a high degree of stability

Since form-closure grasps are a strong condition for stability, they are very useful for applications. Whether form closure can be obtained depends on the design of the end-effector and the geometry of the grasped object. Previously, we proposed a new type of grasping mechanism using closed kinematic chains that can provide form-closure grasps for nearly any geometry of the object. An important design issue is the determination of the link lengths of the closed chain. This paper considers the design with respect to grasp stability. A criterion for evaluating grasp stability is proposed. The link lengths corresponding to an optimal value of the criterion is utilized to obtain a solution for dimensional synthesis. Because the criterion is a nonlinear function of the link lengths, the optimization cannot be obtained by simple computation. To avoid the computational burden in finding the optimal link lengths, we develop a graphical method for determining the link lengths. The grasping of cylindrical objects demonstrates the method