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.

Development of Joint Module with Twospeed Gear Transmission and Joint Lock Mechanism during Driving for Task Adaptable Robot In order to achieve tasks in the real world environment, humanoid robots have motors and reduction drives optimized in relation to weight and size for providing the necessary torque and angle speed. Therefore, having torque or angle speed outside of the predicted range will usually cause the task to fail. In this research, we propose a joint module with a twostage transmission mechanism during driving and a joint locking mechanism during nondriving so that the appropriate torque and joint speed can be attained during the task. By applying the joint module to a tricycle type robot and switching the driving state during the task execution, we were able to both reduce the motor load when lifting heavy objects at driving time and keep high rigidity of the joint at nondriving time.