Development and Evaluation of One-Shaft Type ER Clutch
Norihiko Saga*, Taro Nakamura* and Masaru Nakazawa**
*Akita Prefectural University, 84-4 Tsuchiya, Honnjo, Akita, 015-0055, Japan
**Shinsyu University, 3-15-1 Tokida, Ueda, Nagano, 386-8567 Japan
Electrocrheological (ER) fluids are members of the family of intelligent fluids, and they have a property that their apparent viscosity can be controlled according to the strength of an electric field applied to them. Various applications using ER fluids have been developed. Recently, research on whether ER fluids can be applied to the area of the motion control in robotics has been carried out. For example, we see that robots in factory applications have two links. For safety’s sake, it is necessary to create an enclosure around a large-capacity robot since it is too dangerous for humans to approach such a robot. Thus, we considered that a robot arm would not injure a person if it could bend softly when coming in contact with that person, with a force applied to its tip being controlled skillfully at the joint. In order to realize this bending motion, we aim to develop an actuator to be built into the joint of a robot arm and examine a method of controlling the arm (impedance control). In this paper, we developed a one-shaft type ER clutch to be installed in the joint section of a robot arm. The developed ER clutch was found to be stronger than a conventional ER clutch in terms of radial motion. Further, we examined the fundamental characteristics of the developed ER clutch in order to apply impedance control to it. The results of our experiment show that the coefficient of viscosity is directly proportional to an applied electric field. Therefore, it is concluded that impedance control can be applied to the clutch.
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