Position control of resonant system with load force suppression using wave observer

In industrial applications, reducing the stiffness caused by mechanical constraints, such as using gear, induces a vibration at the tip of a system, which can become a problem. Thus, research is ongoing on vibration control scheme based on a wave equation to suppress all resonances by eliminating reflected waves. However, the conventional method based on the wave equation does not consider robustness against a load force. This paper proposes position control of a resonant system using wave observer to enhance robustness against the load force. In the proposal, the resonant system is modeled as the wave equation containing the load force and control system design is based on the wave equation. Vibration suppression is achieved by a reflected wave rejection, which can suppress all resonances of a resonant system. Moreover, the conventional reflected wave rejection structure is modified to realize robustness against disturbance acting on the motor side. In addition, the wave observer is proposed for eliminating an effect of the load force. Finally, the validity of the proposed method is verified by experiments.