Vibration Suppression Control of Two-Mass Resonant System Based on Gear Backlash Model

Abstract

Motion control technology is developing rapidly due to the improvement of computer performance in recent years. In the motor drive systems such as industrial robots, high-speed and high-precision motion control is required. Many methods have been studied to improve the response by suppressing the vibration due to torsional resonance. Above all, the method based on the feedforward control using the inverse model is effective in order to get the ideal response under the case of less modeling error or disturbance. On the other hand, in many systems such as industrial drives, there is a backlash due to the gears and the joint mechanism between the motor and the load. When the motor torque changes quickly from positive to negative over zero, the gears run idle in the backlash section and the torque shock caused by a collision accelerates resonance and excites vibration. In the systems such as manipulators that frequently switch between positive and negative torque, vibration due to backlash is a particular problem. In this paper, we propose a method to suppress the resonance of a two-inertia system with backlash by feedforward control that considers the nonlinearity due to backlash. The transfer characteristic including the nonlinear characteristic of backlash is converted as the equivalent model of the dead zone characteristic. Then, by using the inverse model of the calculated transfer characteristics, the feedforward control that suppresses the resonance of the spring reaction force including the influence of backlash is constructed. Finally, the effect of the proposed method is verified by simulation in a system which the control of the spring reaction force can be evaluated equivalently by controlling the load displacement.