Active Vibration Control of Multi-Degree of-Freedom Systems by H^∞ Optimal Control Theory (Comparison between H^∞ Optimal Control and Frequency-Shaped LQG Control)

This Paper describes a general control system design method for vibration of a multi-degree-of-freedom system. A H^∞ controller designed on the reduced order model makes the closed loop system not only cause no spillover phenomena, but also control the vibration on the actual model. The solution to H^∞ output feedback control problems is used to design the H^∞ controller. With the result of calculating the example of the four-degree-of-freedom model, the efficiency of the control system is verified. Also, the frequency-shaped LQG control desigh is made in comparison with the H^∞ optimal control. It has been clear that both control methods have robustness to the spillover caused by the reduced-order model in the case of the same weighting functions. The most important result is that the H^∞ optimal control has strongly robust stability to parameter variations, while the frequency-shaped LQG control does not.