Damping control using self-sensing signals for coupled piezo actuators

Piezoelectric actuators are widely used in high-precision equipment where positioning at micrometer range and nanometer accuracy is required. For cost and complexity reduction reasons, some of these applications operate without position feedback. To maintain the desired accuracy level, a combination of charge control and self-sensing based damping control is used, to attenuate hysteresis and reduce settling behavior of mechanical resonances. However, measurement bridge imbalance is known to cause errors in the force estimation. This paper investigates, for a case where multiple piezos are mechanically coupled to the same load, a MIMO off-diagonal control strategy that is robust for these variations.