The artificial lower-limb WL-1 was constructed on the basis of a human’s leg mechanism in 1967. Through biped experiments, we investigated the fundamental functions of a biped locomotion.

　The mechanical model of lower-limbs, WL-3 was constructed which had an electro-hydraulic servo-actuator in 1969. It achieved a human-like motion in a swing phase and a stance phase, and a standing and sitting motion.

　WL-5 had a total of eleven mechanical degrees of freedom; two five DOF legs and one DOF trunk. It could change the direction by using a program control(1971).

　WABOT-1 developed by the late Ichiro Kato and co-works was the world’s first full-scale anthropomorphic robot. It was able to communicate with a human in Japanese and to measure the distances and directions of objects using external receptors such as artificial ears and eyes. Hydraulically powered, it uses disproportionately large feet for stability. A shuffler more than a walker, WABOT-1 realized “static walking” in 1973.

　WL-9DR achieved quasi-dynamic walking for the first time in the world, which used a 16-bit microcomputer as its controller. It had a total of ten mechanical degrees of freedom.

　WL-10R was constructed by the rotary type servo-actuators and carbon-fiber reinforced plastic(CFRP) in 1983. It achieved forward and backward walking, turning on the plane.

　WL-10RD achieved a complete dynamic walking on the plane with the step time of 1.3 s/step using a program and sequence control. Also, the dynamic walking on the uneven terrain such stairs and inclined planes was realized with the step time of 2.5 s/step.

　A hydraulic biped robot WL-12 having an upper body and a two-degrees-of-freedom waist was constructed to realize more human-like motion in 1986. A new control algorithm was developed to improve walking stability, which compensates for moment generated by the motion of the lower-limbs using the trunk motion. The dynamic biped walking was realized under external forces of unknown environments and on unknown walking surfaces.

　WL-12RDIII was able to maintain stable dynamic walking in unknown paths, and stairs in a human residential environment. The dynamic walking was accomplished by the introduction of a new adaptive control method using mechanical hardware and software into the conventional biped walking control method using the trunk motion.

　WABIAN was developed under the following design plan to investigate a cooperative dynamic walking and a collaborative work with humans. (1) The size of the biped robot should be the average size of an adult Japanese woman to do a collaborative work with humans. (2) The robot should be able walk at approximate human speed. (3) The robot should have 3 DOF trunk and 6 DOF arms. (4) The joints of the robot should use electric servomotors. (5) A control computer and motor drives except power supply should be installed. WABIAN had a total of thirty-five mechanical DOF; two three DOF legs, two ten DOF arms, a two DOF neck, four DOF in the eyes and a torso with a three DOF waist. We have realized a various number of walking such as dynamic forward and backward walking, marching in place, dancing, carrying a load, emotional walking, etc.

　WABIAN-RV can various walking motions by online generating and outputting motion pattern on every steps. It is based on the online pattern generation method and this method improve environmental adaptability.
　This year, we propose "the methods of generating and teaching macro command by voice command" for more interactive human-robot interface. Using "macro command" and a voice recognition system developed in this research, a walking motion is generated on the on-motion-mode and the off-motion-mode.
　WABIAN-RV has a total of forty-three mechanical DOF and control systems.