Method and apparatus for controlling position and velocity of a piezoelectric device

An apparatus for controlling position and velocity of a piezoelectric device, comprising:

• a position control circuit operable to receive and compare a first control signal corresponding to a desired position of the piezoelectric device and an estimated position of the piezoelectric device to generate a second control signal in response to the first control signal and the estimated position of the piezoelectric device;
• a velocity control circuit operable to receive the second control signal and to generate a third control signal according to a predetermined velocity profile;
• a piezoelectric device control circuit operatively coupled to said position and velocity control circuits and operable to receive the third control signal and generate a fourth control signal in response to the third control signal that is adapted to drive the piezoelectric device to the desired position and at the desired velocity according to the predetermined velocity profile;
• wherein said position control circuit includes a first data structure operable to determine and correlate an applied voltage to the piezoelectric device with a charge existing on the piezoelectric device to generate the estimated position of the piezoelectric device;
• and
• wherein said position control circuit further includes a current integrator circuit operable to integrate current flowing through the piezoelectric device to determine the charge existing on the piezoelectric device.

An apparatus for determining a position of a piezoelectric device, comprising:

• a voltage sensing circuit operable to determine a voltage applied to the piezoelectric device;
• a current sensing circuit operable to determine a charge existing on the piezoelectric device in response to a current applied to the piezoelectric device;
• and
• a position estimating circuit coupled to the voltage sensing circuit and the current sensing circuit operable to determine a position of the piezoelectric device from the voltage applied to the piezoelectric device and the charge existing on the piezoelectric device.

A method of determining a position of a piezoelectric device, comprising:

• determining a voltage applied to a piezoelectric device;
• determining a charge existing on the piezoelectric device;
• and
• determining a position of the piezoelectric device from the voltage applied to the piezoelectric device and the charge existing on the piezoelectric device.