Development of Electro-Rheological-Fluid Actuators for Driving Artipicial Muscle

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(1) A new method has been devised for obtaining an arbitrary pressure for driving an artificial muscle by controlling the electric field intensity applied to the electro-rheological-fluid. The characteristic of this method lies in that the necessary pressure is generated at the intermediate pressure port by changing the perssure drops based on the shear stress changes in the upper and lower pipes. The relationships among the pressure drops, the flow rate and the shear stress changes, and the equations expressing the pressure response to the electric field application were theoretically derived and compared with the experimental results. The applications of the electric field of pulse-type (digital) variation as well as the linear (analog) control showed that both methods generate the necessary pressure. It was experimentally confirmed that the artificial muscle, if mounted at the middle port, can be driven smoothly even under the alternate voltage field application. Furthermore, the po … More ssibility of driving the fingers independently to each other was examined when the fewer electrodes were used, and this method was proved to be practically applicable.(2) In the next place, the defects of artificial fingers have been improved. The finger is provided with the tactile sense by using a coil-like sensor similar to human's fingerprints. The rigidity is enhanced by equipping the finger with a reinforcing material similar to that of human's bone. A prototype robot hand with four fingers has been manufactured and mounted on an industrial articulated robot. The effectiveness of these robot hand fingers was confirmed throughout the experimental tests of grasping action.(3) A new type of pump hs been developed which effectively uses the electric characteristics of electro-rheological-fluids whose apparent viscosities are changed by the application of voltage. This pump is consisted of the simple flow passage between a pair of rotating opposed disks ; however, can feed the ER-fluids which comprise relatively large dispersed particles and have large viscosities. The principle and configuration of this pump and t;he method of theoretical analysis are described. The pump characteristics such as flow rate, pressure, and the variation of plug-type flow region are examined. It is indicated that this pump is effective not only for the use as a pump but also for the measurements of physical values of the shear stress induced by electric field and the viscosity. Less