In laparoscopic surgery, retracting internal organs is required for appropriate visibility and workspace. It is desired that retracting instruments be less invasive and conform better to organ surfaces. An assemblable three-fingered retractor-hand was previously developed. It had three active joints driven with wires. In this research, a new assemblable three-fingered hand is developed. The fingers of this hand are equipped with hydraulic driven bending joints, which enables simplification of the mechanism and safe retraction. There are advantages of using a hydraulic drive system such as; easier power transmission and therefore higher transmission rate. Fingertip forces are equalized and can be estimated with the help of a water pressure gauge. In addition, the load torque, at which the fingers are extended, can be adjusted by modifying precompression. Also, the hydraulic joints provide adjustable compliance because of the elasticity of the tubes in the flow path. Those benefits are verified by experiments, and an in vivo experiment is conducted.

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Direct Injection engines have strongly penetrated the gasoline engine market for their benefits of reduction in fuel consumption. A high-pressure gasoline pump is one of the important components of a DI engine. A recent trend for the pump is to increase the operating pressure. On the other hand, there are certain limitations on maximum system pressure, which is the sum of the pressure loss of the relief valve and other margins. Under such circumstances, it is essential to reduce the pressure loss of the relief valve in order to minimize the system maximum pressure. We have investigated the cause of the pressure loss of the relief valve by making a 1D simulation model of a high-pressure gasoline supply system, and found that the clearance between the valve and seat causes the dominant pressure loss due to it’s smaller lift. We have proposed a new valve design that can achieve a larger lift. As a result, we have lowered the pressure loss of the relief valve.

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In order to realize a pneumatic artificial rubber muscle (PARM) with high damping characteristics, we have developed a new actuator combining an ordinary PARM with a rubber bellows that uses a narrow tube as an air throttle. In the present study, in order to experimentally clarify the dynamic characteristics of the newly developed high-damping PARM, two of the newly developed high-damping PARMs driven by a spool-type servo valve are connected in parallel to a link that has a rod as an inertial load, constituting the driving system of a single joint. The same experiment was carried out using ordinary PARMs, and the superiority of the newly developed PARM is demonstrated. The characteristics of each component of the high-damping PARM, such as the PARM, the rubber bellows, the narrow tube, and the servo valve, are modeled assuming nonlinearity. Then, using MATLAB/Simulink, a nonlinear simulator for the newly developed actuator is developed. The simulation and experimental results indicate that the developed simulator is helpful in designing the newly developed pneumatic actuator.

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