Kiyotoshi Matsuoka
The Matsuoka oscillator has been used to control various robots that perform rhythmic movements. The oscillator-driven control system usually takes a feedback structure. While the oscillator actuates some part of a controlled object, some state variable of the object is fed back to the oscillator. An important property of this control scheme is that the oscillator comes to drive the object at its natural frequency, not at the inherent frequency of the oscillator. Although there are some works that intend to elucidate the mechanism of this resonance tuning, they are mostly based on simulations or graphical analyses. It seems therefore difficult to draw a clear, general conclusion from those results. This article expresses the input-output relation of the oscillator in a form of describing function. Based on the function, the unique characteristics of the Matsuoka oscillator and the mechanism of resonance tuning are explained clearly.