Development of a Grasping Method Using Fingers with Vibration Absorbed by a Dynamic Damper

This paper describes the initial grasping process of a new vibration gripper. The gripper can handle an object of unknown weight and unknown surface conditions with its most suitable grasping force. The gripper is constructed so as to have two parallel fingers. Each finger consists of a structural finger, a main spring, a grasping finger, an absorber spring, and an oscillator block. These parts in each finger compose a series mass-spring system having two degrees of freedom. An external force with the natural frequency of the system composed by the oscillator block and the absorber spring is operated on one of grasping fingers. In the initial grasping process, the gripper can grasp the object in the most suitable grasping condition in which the grasping force is regulated at the optimum value, and both the grasping fingers and the object are stabilized in a stationary condition because their vibrations are absorbed by dynamic dampers composed of the oscillator block and the absorber spring. In this paper, the initial grasping process divided into five steps is described, and the most suitable grasping condition is analyzed theoretically and is confirmed by experiment.