To enable a humanoid robot to use its hand in the whole body motions, such as hanging, climbing or using a ladder, we developed a robot hand driven by a powerful but backdrivable cluster EHA. A miniature crescent trochoid pump with high discharging pressure was developed. The design of a direct casted cylinder manifold with low hydraulic friction is also presented. Results of basic experiments such as maximum output force, speed, position and force controllability and backdrivability are shown in the end of this paper. A movie of grasping demonstration is also attached.

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The knowledge on the actuator is important in designing a robot that would operate as expected. Stall torque and no-load speed are often used as the measure of actuator performance. When the robot makes interaction with environment, the load condition changes. For the robots that make interaction as a primary objective, the performance of actuators under different load condition should be investigated in order to make a good estimation of the robot performance. In this paper, we propose a test equipment that utilize inertial force to apply force to the actuator while it is moving. The application of this equipment for evaluating miniature electro-hydrostatic actuator is reported.

Actuator of robot hand need to be powerful enough to support whole weight of the robot and physically pliable to avoid damage since the hand is not only used as manipulator, but also to support the movement of the robot such as hanging or using a ladder. The objective of this research is to propose a new design of elector-hydrostatic actuator (EHA), a class of backdrivable actuator, cluster to activate tendon driven anthropomorphic robot hand. This paper explains composition and design concept of the EHA. Detailed design of the actuator including miniature high output pressure low friction pump and casted hydraulic cylinder is presented. Simulation of its performance and result of a experiment is also shown.