Technology: On Limbs of Steel

When they built their strange-looking vehicle five years ago, engineers at Aerojet's Space-General Corp. in California were aiming for space. Their Moon Walker had six legs, stereo TV for eyes, and was crammed full of detection and communications equipment. It was designed to land on the moon with a Surveyor spacecraft.

The Moon Walker was rejected by NASA, but it was not discarded by Aerojet. Rebuilt in a modified version, it has become the prototype of an eight-legged, walking wheelchair now being evaluated by the University of California at Los Angeles for the use of handicapped children. The boxy gadget resembles an ungainly bug; yet it is capable of sophisticated locomotion. It can travel forward or backward, turn in its own length, climb steps, a 30° slope and an 8-in. curb, cross rough fields, and literally get a toehold in sand or muddy ground that usually bogs down a wheeled vehicle.

Moon Walker's agility derives from its stainless-steel tubular legs, which have hinged, almost human knees, and flat, hooflike feet with rippled soles to give them traction. The legs operate in pairs, one leg of each pair supporting the walker's weight while the other leg is in motion. They are moved by battery-operated electric motors and controlled by a four-way lever that is so sensitive a multiple-amputee child can operate it with his chin.

In tests conducted by U.C.L.A. at a suburban Los Angeles hospital, researchers found that severely handicapped children could easily handle the walker, although they felt that its H-m.p.h. speed was too sedate. Because the walker's feet tend to jolt passengers at higher speeds, Aerojet is planning to add wheels to the vehicle. With wheels, a child will be able to roll around floors and sidewalks at 2½-m.p.h. — a normal walking pace. When he comes to a curb or a rut-filled field, he will flick a switch, lower the tucked-up legs, and walk across the obstacle on limbs of steel.