Vibration Absorption Control of Industrial Robots by Acceleration Feedback

This paper describes an electrical control method of absorbing arm vibrations of industrial robots. Arm vibration problems are divided into two categories: resonance vibration phenomenon depending on actuator velocity and transient oscillations caused by acceleration change of actuators. Because resonance frequency of an industrial robot changes more than double due to the arm posture, mechanical vibration absorbing methods may not be easily utilized. The method applied in this paper is to compose dampers as electric manners by utilizing arm acceleration feedback to actuators of an industrial robot. Acceleration sensors are attached on three axes which construct a robot arm. Acceleration signals are fed back to the corresponding actuators passed through phase compensation circuits. By experiments applied to an industrial robot, this method has been proved to be effective in eliminating both resonance and transient vibrations. According to this control, a smart motion industrial robot which does not have resonance characteristics and operates speedily and smoothly has been realized.