Automatic Balancing Apparatus Using Ultrasonic Motor.

In order to suppress vibration due to unbalance of rotating spindles, many kinds of automatic balancing apparatus have been developed so far. However, they cannot work sufficiently at a high rotational speed because of incorrect actions of such mechanisms in a rotating unit of the apparatus as a compensating mass movement mechanism, power supply mechanism, etc. Most of the incorrect actions are caused by complexity of the mechanisms. In this research, a balancing apparatus composed of highly simplified mechanisms has been newly developed by utilizing ultrasonic motors which can rotate at a very low speed without any reducer and stall withoutany brake. In the rotating unit of the developed apparatus, two ultrasonic motors on a rotor of which a compensating mass is stuck, printed circuit boards and rechargeable batteries as a power source are equipped. The unit is installed on the objective rotating spindle so that the motor axes may be aligned with the spindle axis and the motors are driven through infrared PCM signal from the stationary unit. Software suitable to control the hardware has been also developed by adopting the steepest gradient method.