System design and study of bionic eye based on spherical ultrasonic motor using closed-loop control

We present a novel bionic eye based on spherical ultrasonic motor (SUSM). SUSM is a compact mechanism occupying little space but good responsiveness, high positioning accuracy, high torque at low speed and strong magnetic field compatibility. With those advantages, the bionic eye easily implements some human eye movements. It is constructed from an eyeball, three driving stators, three preloaded apparatuses and some supports, and has three degrees of freedom (3-DOF). The eyeball is driven by frictional forces from three same annular stators attached with several piezoelectric elements. A velocity closed-loop control by piezoelectric element is utilized to improve the eyeball's rotational velocity driven by each stator. An attitude sensor is mounted in the eyeball to improve its integrated position accuracy by a position closed-loop control method. The experimental results indicate the availability of our bionic eye and the validity of the closed-loop control methods.