2001 Fiscal Year Final Research Report Summary
Grasping Force Control of Robot Hand with Fingers using Ultrasonic Motors
| Project/Area Number |
12650257
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Intelligent mechanics/Mechanical systems
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| Research Institution | Daido Institute of Technology |
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Principal Investigator |
NISHIBORI Kenji Daido Institute of Technology, Dept. of Engineering, Professor, 工学部, 教授 (50115614)
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| Project Period (FY) |
2000 – 2001
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| Keywords | Ultrasonic Motor / Robot Hand / Grasping Force / Pulse Width Modulation / Self-Locking / Friction Force |
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| Research Abstract |
Utilizing ultrasonic motor (USM) for the robot hands, the high quality robot hands will be realized since the ultrasonic motor has a simple structure without coils, a high response, large torque at low speed, and a self-locking at rest. Little research, however, has been reported regarding the torque control by use of the self-locking of the ultrasonic motor. This study proposes a grasping force control by PWM (pulse width modulation) when the robot hand rotates a cylindrical body by three fingers.
In the case of ON-OFF type PWM, the large self-locking friction can be obtained even at the small duty ratio. However, the relation between the duty ratio of PWM and the static torque indicates nonlinear and a large hysteresis occurs. It was confirmed that the introduction of a standing wave to a traveling wave-type ultrasonic motor diminishes the self-locking friction. In this case the relation between the duty ratio of PWM and the static torque of ultrasonic motor becomes almost linear when the standing wave is induced to the USM in the OFF period of PWM.
It is confirmed that the driving characteristic of the ultrasonic motor depends on the switching frequency of the PWM. At the case of the switching frequency of fs=500Hz it was observed that the standing wave reduced the driving force of the USM. In this case, the USM regains the linear torque characteristic after suppressing the strength of the standing wave. In addition, this study proposes the method to stabilize the driving characteristic of a robot hand that rotates a cylindrical body. Three fingers work as the vibration-type of ultrasonic motors. The driving frequency of the ultrasonic motors follows the resonance frequency by the feedback of its vibration amplitude.
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Research Products
(4 results)
