Design and performance of a rotary motor driven by piezoelectric stack actuators

The development of a rotary inchworm-motor using piezoelectric actuators is presented. The motor design has the advantage of a macro and micro stepper motor with high torque and speed. The design is capable of fast angular positioning with micro level accuracy. The rotary motor, as designed, can also be used as a clutch/brake mechanism. A constructed prototype motor along with its characteristics are presented. The motor consists of a torsional section that provides angular displacement and torque, and two alternating clamping sections which provide the holding force. The motor relies on the principal piezoelectric coupling coefficient (d(33)) without torsional piezoelectric elements. This design eliminates bending moment and shear applied to the actuator elements and thus increases its torque capability. An innovative flexure design is introduced and consideration is given to contact elements which affect the performance of the motor. Experimental results demonstrating the prototype's performance based on the aforementioned design considerations are presented.