Artificial Arms and Hands

The study of artificial arms and hands began in 1967 incorporating the technological assets gained from developing the active prostheses started three years before. The studies had at first aimed only to develop machines to perform manual labor in lieu of persons and emphasized development of artificial hand mechanisms. Recently the aim has been to develop robots which can perform intelligent work as well as manual labor.

WAM-1 (1967)

WAM-2 (1969)

First Stage WAM Series: WAM-1, 2, 3 (1967~1970)

WAM-1 was first developed in 1967, in which WASEDA-type artificial muscles made of rubber (cf. page 7) were used. WAM-1 featured seven degrees of freedom (DOF), four in the hand and three in the arm. In 1969, the computer-controlled WAM-2 was assembled featuring five electrically actuated DOFs in the arm. The WAM-3, a further refinement of the WAM-2, was developed in 1970. WAM-2 and 3 had the position sensors and the pressure sensors on their fingers so that they could automatically grasp and transport objects.

WAM-4 (1972)

Expansion to the WABOT-1 (1971~1972)

The development of the WAM-4 was started on the basis of the previously developed models, the WAM-1, 2 and 3, and was completed in 1972. The WAM-4 consisted of six DOFs in the arm and one DOF in the hand. The right and left hands were both developed as the upper limbs of the intelligent robot WABOT-1 (cf. page 5). WAM-4 detected objects using a visual sensor and tactile sensors attached to its fingers, and grasped and transferred or shifted objects from one hand to the other using symmetric bilateral contro1.

WAM-6 (1980)

Force Control and a Redundant DOF (1973~1980)

Studies of an anthropomorphic artificial arm having a redundant DOF 1ike a human arm were started in 1973. In 1974, one concept for control adaptable to external constraints, named the "Torque Position Contro1", was proposed. The development of the WAM-6, which had seven DOFs in the arm and two DOFs in the hand, was started in 1975 and completed in 1979. Electro-hydraulic servo-actuators, RSA (Rotary Servo Actuator) were introduced and torque feedback was managed by the strain gauges attached to each joint of the WAM-6. In 1980, three-dimensional Torque-Position Control was applied to the WAM-6, making it possible to open a door and paint a curved surface.

WAM-7 (1983)

WAM-8, WAM-7R and WAM-8L (1984)

Keyboard Playing Robot (1981~1989)

The task of developing a dexterous robot that could move quickly and act intelligently began with the challenge of trying to construct a robot that could play a keyboard. In 1982, tapping a key in ten times per second was realized by artificial fingers to which the driving force was transmitted through cables. In 1983,the WAM-7 with seven DOFs in the arm and fourteen DOFs in the fingers was developed and it could play simple tunes. Four limbs, the WAM-7R (left arm), the WAM-8 (right arm), the WAM-8L (legs) were successively developed in 1984. They had fifty DOFs total and played the electronic organ, tapping fifteen times per second. The software algorithm based on artificial intelligence software that could read a musical score automatic any determined the cooperative movement of the fingers and arms. The WAM-8 had the ability to perform middle-level tunes.

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