Adaptability analysis, evaluation and regulation of compliant underactuated mechanisms

There are few mathematical indices to quantize the adaptability, although it is mentioned repeatedly as a highlight of underactuated mechanisms in literatures. This paper discusses the grasp adaptability of underactuated mechanisms. Different from compliance, namely the reciprocal of stiffness, the adaptability is presented as the ability of adaptive motion. Two measures of adaptability are proposed from two aspects respectively: the impact on the grasped object and the enforcement cost of the underactuated mechanism. Based on the measures, the trend of the adaptive grasping process is predicted in enveloping grasp with a simple gripper, and a corresponding experimental prototype is set up to verify the calculated results. As an application, we apply the two measures to analyze and compare the adaptability of three typical underactuated mechanisms.