Micro electrostatic wobble motor with toothed electrodes

A micro electrostatic wobble motor with toothed electrodes has been designed using a newly proposed tooth profile, which we call the "composite profile". This new design results from considering the profile of the non-contact area, on which the generated electrostatic torque depends. The new tooth profile eliminates slip between stator and rotor, so complete wobble motions are achieved even when a large load is applied. A micro wobble motor based on this design was fabricated by micro-wire electrical discharge machining. The motor is 6 mm in gear pitch diameter and 3 mm in thickness. The module of the teeth is 0.063, and the tooth numbers of the stator and rotor are 96 and 95, respectively. Experimental results show that the stall torque was about 0.015 mNm with a 350 V supply and the motor maintained an almost constant speed and full wobble motion until just before stalling. We conclude that toothed electrodes with the proposed profile are a very effective way to achieve complete wobble motion even when a large load is applied.