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22:06
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MERITS AND DEMERITS
Merits
- Low speed and high torque - direct drive
- Quick response, wide velocity range, hard brake and no backlash: excellent controllability; fine position resolution.
- High power/weight ratio and high efficiency.
- Quiet drive.
- Compact size and light weight.
- Simple structure and easy production process.
- Negligible effect from external magnetic or radioactive fields, and also no generation of these fields.
Demerits
- Necessity for a high frequency power supply.
- Less durability due to frictional drive.
21:56
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PRINCIPLE OF WORKING
The working principle of Ultrasonic motor is shown in figure. High order curling vibration is generated on the surface of the elastic vibrator (stator) and travelling eaves are made by excitation of the piezoceramic vibrator. And the certain pressure causes the slider to propagate on stator by the friction between them. Driving force of Ultrasonic motor is obtained by travelling-wave type elastic curling wave. This type of motor is named as travelling wave type Ultrasonic motor. For generating elastic curling wave on the elastic annular plate, adhere the piezoceramic vibrator beneath the annular plate and exploit the expanding and contracting wave. That is piezoceramic vibrator beneath the elastic annular plate is polarized and when AC voltage is applied to the vibrator, sectional expanding and contracting move occurs and elastic curling waves are generated on the elastic annular plate
21:39
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ROBOTIC HAND DRIVEN BY ULTRASONIC MOTOR
Five fingered robot hand driven by 20 ultrasonic motors. Each finger has five degrees of freedom. The size is about the same as that of human hands. As ultrasonic motor has characteristics such as rapid response, large torque and silence, it is adequate for robot hand. Speed of fingers is faster than that of humans. So this hand is adequate for use in master-slave system for remote control in the medical and extreme environment. Now researches aiming to construct a master-slave system to show the applicability of our hand to dexterous manipulation
