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This paper presents Micro Hydraulic Actuator (MHA). MHA has high power density and it is small enough to be installed inside of a small robot, such as humanoid robots. MHA consists of a cylindrical cam mechanism, pistons having ball joints, and combination of a valve plate and a cylinder block. The cylindrical cam has a Modified Sine (MS) curve and dwells at the trapping region of the cylinder ports on the cylinder block. The valve plate has slot ports in a circumferential direction on the inside and it induces high-precision contact with the cylinder block. In this study, MHA is designed and produced focusing on the mechanisms mentioned above and the applicability of the humanoid robots through the performance test is verified.

We develop a kind of active cannula robot (microsurgery system) used in minimally invasive surgery. This robot mainly consists of two parts: active cannula and control unit. The active cannula is composed of two or three concentric pre-curved elastic tubes that can be translated and rotated relative to one another. Each tube is driven by a motor with a decelerator. Elastic interaction is caused as tubes are translated and rotated relatively, which reshape the cannula to bypass the barriers. In addition, vision system is also integrated into our system. However, when the micro-camera fastened to the tip of cannula rotates together with the active cannula, the orientation of object presented on the monitor is always changing, which will complicate manual dexterity among surgeons. To solve this problem, we design a real-time misorientation auto-recovery algorithm for calibrating the rotation angle and confirm it by experiment.

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