Piezoelectrically driven rotation stepper motor for high resolution movings

A piezoelectrically driven stepper motor has been developed for angular resolutions in the range of seconds. The motor operates on the basis of a modified Inchworm-Principle. For driving low voltage piezoactuators of 28 mym maximum expansion and with a mechanical transmission for increasing the expansion to 200 pm have been applied. The maximum rotation step is 1,7' for 200 V control voltage. The angle resolution is depending on the stability of the control voltage, we measured 0,025". For the rotation rate a value of 8 degree per minute has been measured. The torque of the motor is smaller than 1 Nm.