Patent ID: 7187102

Claim:
A method for controlling a piezoelectric motor, the piezoelectric motor being configured to move a driven element when a sinusoidal electric signal of a first frequency is supplied to the piezoelectric motor with an amplitude that is sufficient to move a driven element a predetermined distance, comprising: selecting a predetermined first sequence of frequencies, the first sequence of frequencies comprising at least two mutually different frequencies; creating individual waveforms corresponding to each frequency of the first sequence of frequencies so that each individual waveform has a predetermined finite duration and amplitude and is periodic with a period that is the inverse of the corresponding frequency; concatenating the individual waveforms into a single first electric signal and supplying said signal repeatedly to the piezoelectric motor to move the driven element; and wherein the selected first sequence of frequencies comprises a sufficient number of frequencies that are distributed to cause the piezoelectric motor to move the driven element even when the properties of the piezoelectric motor change within a predictable range.