Control system for high precision positioning applications based on piezo motors

In this paper implementation of a control system for high precision applications is presented. The control system is developed for a Piezo LEGS motor, which is a walking piezo motor that can be employed in nanometric precision applications. In the control system structure, two main components are digital signal controller which executes control algorithm and power driver that is generating driving voltages for the motor. The waveforms of the driving voltages are designed using a recently presented coordinate transformation. This transformation enables synthesis of driving waveforms according to design requirements regarding force imposed to the motor´s rod and rod´s x-direction trajectory profile. In this work, the waveforms are selected to ensure no relative motion between the motor´s legs and rod, and constant velocity of the rod within one step. Control algorithm is named as virtual time control. Despite its simplicity, the algorithm allows high precision positioning which is very close to theoretically achievable one.