Study on Micro-gap Flow Behavior of Electrorheological Fluid and Its Application to Haptic Display System

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ER fluids are one of an exciting family of functional fluids, which show dramatic and reversible rheological changes in several milliseconds when the electric field is applied. In this research, featuring the possibility of miniaturization of ER mechanical elements such as brake, damper and valve due to their construction using only electrodes, the following investigations have been done in order to develop Braille display system utilizing electrorheological fluids as one of haptic display systems.(1) As the fundamental flow fields in designing ER fluid micro system, three flow configurations of a pressure flow, a rotational shear flow and a oscillatory squeeze flow were focused on in this research. For two kinds of micro-particle ER fluids and one kind of nano-particle ER fluid, the micro flow behaviors in the above three flow configurations with an about 0.05-0.3mm micro gap was clarified by flow visualization in close relation to each ER characteristic, and the ER fluid suitable for … More the micro gap flow system and the optimal design concept for applications were shown.(2) The 3-ports micro ER valve, and the diaphragm micro-actuator consisting of two ER valves utilizing a micro-particle ER fluid were fabricated by the photolithography method. The flow rate control characteristics for the 3-ports micro ER valve and the diaphragm response characteristics of the micro-actuator under PID position feedback control were investigated, and the possibility for the ER diaphragm micro-actuator to apply to the Braille display system was evaluated.(3) An ER micro-actuator with a micro-bellows, which performed enough stroke and push-up force for one pin of the Braille display system, was fabricated by the photolithography method and the actuating performances were evaluated experimentally. It was found that ER fluid supply pressure of more than 550 kPa was needed for the developed micro actuator to perform a stroke of 0.5 mm and a push-up force of 0.15 N of the Braille pin. The Braille pin mounted to the top of the micro-bellows of the actuator was driven by applying an on-off control strategy to two ER valves of the actuator. Less