Characterization and control of a 1-DOF monolithic piezoactuator (MPA)

The Monolithic PiezoActuator (MPA) described in this work proposes the amplification of the piezoelectric deformation by a lever mechanism designed in a bulk piezoceramic plate. The advantages of the monolithic approach are to make the structure compact and to avoid problems of assembling reducing consequently production costs. In addition, several DOF (Degree Of Freedom) MPA can be designed with this approach. The total displacement using the MPA can reach some microns for a few millimeters size device. A numerical model has been used to simulate the static and dynamic behavior of a 1 DOF MPA. Static and dynamic measurements show a maximum displacement of around 6 mm and bandwidths as high as 5 kHz. The second part of this work is devoted to the open-loop position control of the MPA. The piezoelectric actuation is generally known to have a static behavior with a good linearity. Actually, when such an actuator is controlled by the electrical voltage, the typical hysteresis between this voltage and the corresponding deformation of the actuator can reach 20% for a soft PZT. Experimental results show an hysteresis under 10% and weak non-linearity for the MPA compared to standard piezoactuators. In order to linearize the open-loop motions, an open-loop control device which control the quantity of free electrical charges on the micro-actuator has been developed. The implementation of the control method has also given very encouraging results for MPA prototypes used in the laboratory.