Piezoelectric motor control

摘要

A piezoelectric system has a piezoelectric motor ( 20 ) driving a driven element ( 22 ) so as to move the driven element ( 822 ) in response to an electric signal ( 25 ). The motor ( 20 ) has at least a first optimal operating frequency at which the motor ( 20 ) moves the driven element ( 22 ) an amount that meets predetermined criteria. The motor ( 20 ) and driven element ( 22 ) have a desired performance criteria when operated at that first operating frequency. A plurality of concatenated sinusoidal sweeping frequencies are repeatedly supplied to the piezoelectric motor ( 20 ) with at least one of the sweeping frequencies being sufficiently close to the first operating frequency to cause detectable motion of the driven element ( 22 ). The frequencies are varied in response to movement of at least one of the motor ( 20 ) and the driven element ( 22 ) to produce an average performance of the motor ( 20 ) and driven element ( 22 ) for a time corresponding to the time for one sweep of frequencies. The average performance is greater than an actual performance of the driven element ( 22 ) for the same period of time but when the actual performance is less than the desired performance.