Underactuated Elements Design Criterion for Envelop Gripper Mechanism

Linkage underactuated gripper mechanism can perform powerful and compliant envelope grip for different shape objects. Due to the underactuated elements like spring in the mechanism, underactuated gripper is easy to be disturbed by external interference. The stability of the underactuated gripper is related to the grip configuration and the design parameters of the underactuated elements. In this paper, the dynamic equations of an underactuated gripper are established by analyzing the relationship between the grasping state and the small displacement with force. The equivalent stiffness of the underactuated gripper contact object is obtained. The dynamic equation of the grasped object is established and the energy function is constructed. The dynamic contact stiffness matrix of underactuated passive self-adaptive envelope is obtained. The dynamic stability criterion for underactuated gripper is deduced. The grasp configuration and parameters design criterion with the stability condition are obtained.