Development of an Intelligent Gripper with a Dynamic Vibration Absorber

Abstract

An intelligent vibration gripper has been developed. The gripper can handle an object of unknown weight and unknown surface condition with the most suitable grasping force. Additionally, the gripper can adapt the grasping force to the most suitable value for the object even if the weight or the surface conditions of the object change. The gripper has two parallel fingers. Each finger is composed of a mechanical vibration system having two degrees of freedom. The system consists of a main mass block and an oscillator block, and these blocks are connected by two springs. In the main mass block, a harmonic force is always generated and absorbed by a dynamic damper consisting of the oscillator block and a spring, so that the main mass block is kept in a stationary condition and the oscillator block vibrates with a constant amplitude. The object is grasped between both the main mass blocks. When the object is grasped with the most suitable grasping force, not only the object and both main mass blocks become stationary but also both oscillator blocks become stationary because harmonic forces are transmitted to the object from each main mass block and the two harmonic forces cancel each other out. In this gripper, the grasping force is adjusted to the most suitable value as the amplitudes of both oscillator blocks are reduced to zero. This paper describes a fundamental principle of this intelligent gripper and the principle is confirmed by experiment.