For multi-DOF (degree of freedom) actuator systems used in power microrobots that perform power-needed tasks in narrow space, we had proposed and developed an alternating pressure system using ER microvalves, which can supply power to each actuator with only one pipe by synchronously rectifying an alternating flow with ER microvalves. The ER microvalve controls the flow of functional fluid ERF (electro-rheological fluid) with its apparent viscosity increase when subjected to an electric field, and has simple structure without sliding parts. However, complete elimination of internal bubbles in the ERF is required not to degrade the system response, and this process is time-consuming. To overcome the problem, in this study, we proposed and investigated a novel alternating pressure system using ER clutches that does not require complete elimination of internal bubbles in the ERF. First, the novel alternating pressure system was proposed. The system consists of an input part with a hydraulic cylinder, an output part, a fixed part, ER clutch A between the output part and the input part, and ER clutch B between the output part and the fixed part. The reciprocating motion of the input part due to the alternating pressure was rectified with synchronously switched ER clutches A and B. Second, the static and dynamic characteristics of an ER clutch was experimentally investigated. The step responses for the moving distances were clarified and modeled. A “dead zone length” was defined. Third, based on the results, a linear actuator and a linear actuator large model for principle verification were designed. The linear actuator large model was fabricated, and its mathematical model was constructed. The system motion and characteristics were clarified experimentally comparing with the simulation results. Finally, to increase the output displacement, a bending actuator was proposed, fabricated, and characterized.
MORI et al. (Thu,) studied this question.