a stick - slip piezo motor . a piezo housing holds at least two piezo elements . the piezo elements are both rigidly connected to the piezo housing . at the end of each of the piezo elements is a piezo friction element . each of the piezo friction elements is in friction contact with a moving friction element . while oscillating between a stick phase and a slip phase , both of the friction elements operate in conjunction to move the moving friction element in a desired travel direction . the piezo elements oscillate out of phase such that when one of the oscillating piezo elements is operating in the slip phase and moving in a direction opposite to the desired travel direction , the other oscillation piezo element is operating in the stick phase and is moving in the travel direction in order to counteract and overcome unwanted dragging of the moving piezo element .