Visual Servo Control System of a Piezoelectric2-Degree-of-Freedom Nano-Stepping Motor

A nano-stepping motor can translate or rotate when its piezoelectric element pair is electrically driven in-phase or anti-phase. It offers millimeter-level stroke, sub-micron-level stepping size, and sub-nanometer-level scanning resolution. This article proposes a visual servo system to control the nano-stepping motor, since its stepping size is not consistent due to changing contact friction, using a custom built microscopic instrument and image recognition software. Three kinds of trajectories&mdash
straight lines, circles, and pentagrams&mdash
are performed successfully. The smallest straightness and roundness ever tested are 0.291 &micro
m and 2.380 &micro
m. Experimental results show that the proposed controller can effectively compensate for the error and precisely navigate the rotor along a desired trajectory.