Vibration Control of a 2 Mass Resonant System by the Resonance Ratio Control.

Recently, with the progress of robust control techniques, the resonance of mechanical systems becomes a more important problem. This paper presents a position control method to suppress the torsional vibration of a 2 mass resonant system. Here we propose a sensorless control of arm portion. In this case, it is necessary to estimate some states of the arm portion. When motor portion parameters are well known due to several identifications, the reaction torque caused by the shaft torsion can be estimated. This reaction torque feedback makes it possible to control the resonance frequency between the torque current and the motor position. Here, we introduce a new concept which is called “Resonance Ratio”. The resonance ratio is determined arbitrarily by the feedback of the reaction torque. The proposed method is a reasonable concept from a mechanical point of view.The proposed control system is based on both the conventional PD control and the resonance ratio control. Then any sensor information of the arm portion is not used, and the proposed controller is a very simple structure. This is one of the remarkable points of the proposed method. We discuss an idea of the determination method of controller gains. The validity of the proposed method is also proved by several experiments.