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A driving method of piezoelectric actuator by using current pulses

Piezoelectric actuators have a potential for high displacement resolution. However, in the case of driving through a digital-to-analogue converter, its resolution restricts the ratio of the deformable range to the resolution of the piezoelectric actuator. This study aims at displacement control with high resolution throughout the deformable range by driving with a series of current pulses. In this paper, a driving method with the intention of applying pulse density modulation control is proposed and the results of the displacement control of a stacked piezoelectric actuator are described. In the feed-forward control, the hysteresis and nonlinearity in the drive by the current pulse were much smaller than those by a voltage linear amplifier because the driving pulse with a constant duration can be regarded as a charge pulse. In the feedback control with a PID controller, the displacement could follow the reference. Therefore, the driving performance was as good as that using the voltage linear amplifier.