WLRII, a Hoseless Hydraulic Wheellegged Robot The performance of traditional hydraulic robots is often limited by their hoses across moving joints or connecting hydraulic drive units, which would reduce their mobility and impede their ability to operate in complex environment. In response to this deficiency, this paper introduces the WLRII (the second generation of wheellegged robot), a novel hydraulic wheellegged robot developed by using hoseless design approach which is focused on improving the reliability of the hydraulic system and perfecting the appearance of the robot. As its notable features, seven Hydraulic Hoseless Joints (HHJ) that include a pair of high and also low pressure oil pipes based on rotary seal, CylinderValveSkeleton (CVS) integration thighs and arms which are produced by subtractive manufacturing as well as oscillating cylinders driven by gear rack transmission are included. In addition to a description of its design, experimental characterizations of rough pavement adaptability and payload capability together with the achievement of the reliability of hydraulic system are also demonstrated. As a result, we confirmed effectiveness of the hoseless design by moving on the rugged ground, climbing slope, squatting with load, dragging and picking up a heavy load. To the authorsxe2x80x99 best knowledge, this is the first time that the design of a hoseless hydraulic wheellegged robot has been presented.

Experimental Validation of Hydraulic Interlocking Drive System for Biped Humanoid Robot Biped robots require substantial amounts of power on each leg alternately while walking, hopping, and running. However, it is difficult to adopt large highpower electrical motors in conventional mechanical transmission systems owing to spatial limitations. To address this problem, a hydraulic interlocking drive system that incorporates two hydraulic directdrive systems is proposed for biped humanoid robots. The hydraulic interlocking drive system connects the two hydraulic directdrive systems and concentrates the pump output on one side cylinder. The other side cylinder meterin flow rate is controlled by the meterout flow rate from the cylinder on which the pump is concentrated. Good position tracking and excellent energy saving are achieved with the proposed system. A performance comparison with a single hydraulic directdrive system shows that the motor power of the hip pitch joint is reduced by 27.3% for walking patterns. This result shows that the rated output of the motor can be reduced, and smaller and lighter motors can be installed in biped robots.