Optimum synthesis of a 10-link gripping mechanism using new grasping indices

Abstract

When the traditional grasping index is used as an objective function, the optimized mechanism obtained offers good force transmission performance but unsound motion transmission for a 10-link gripping mechanism. Therefore, we first propose a new grasping index that is the product of the traditional grasping index and the effective force ratio. The effective force ratio reflects the motion transmission for the output links. The proposed grasping index is similar to the force transmission index discussed in the literature; however, different views of the physical meaning of the two components of the index and the necessity of the effective force ratio for optimum synthesis of the mechanism are presented. The second new grasping index proposed is the product of the first grasping index and the cosine value of the angle between the contact force and the contact velocity, originally used as a constraint. Using these new grasping indices, one can obtain sound optimum mechanism designs with a very small input force and contact velocity and with the maximum opening dimension equal to the object size. Furthermore, optimum synthesis for the gripping mechanism with an opening dimension larger than the object size is also investigated.