New Control Method for Robot Joint by Mechanical Impedance Adjuster. Proposition of Mechanisms and Application to Robot Finger.

Abstract

This paper proposes an ideal control method for the adjustment of joint impedance of manipulators, by using mechanical elements such as Leaf Spring and Pseudo-Damper by a Brake. The proposed method can realize an ideal characteristics of impedance compared to conventional active force control methods which performances are limited by the responses of the servo systems, the non-linear characteristics of the force sensors and the dynamics of the manipulator. Compliant following motions in cases of sudden changes of external forces is expected. Concretely a compliance adjustment method using the spring mechanism, the structure and control of the Pseudo-Damper system, and simple control algorithms for the coordinated system are mentioned.The effect of our mechanism and methods are shown by an experiment of adjusting the joint impedance to appropriate levels including very compliant conditions and positioning, by using the 1-D. O. F. Finger Model which the new joint mechanism is applied to robot fingers.