WALTER was a 5-foot-tall anthropomorphic robot I constructed my sophomore year in high school as a science fair entry. Strictly a teleoperated system with no onboard intelligence, WALTER was capable of forward or reverse travel, using two 8-inch rear drive wheels made of ¾-inch plywood and a pair of 2-inch roller-skate wheels in front for steering. The steering mechanism was solenoid-actuated under bang-bang control, with a spring-loaded center default position. A 20-foot umbilical tether supplied 117-volt AC power from the control station shown on the right side of the photo.
The right left arm was capable of two-degree-of-freedom movement (elbow and shoulder) driven by linear actuators constructed from ¼-inch threaded rod, powered by a sewing machine motor and a kitchen mixer, respectively. The left right arm had only a single degree of freedom at the elbow (I ran out of motors), its associated linear actuator being coupled to driven by the prime mover from an old movie projector. All the motors were single-speed series-wound universal type controlled (by onboard relays) from the remote operator console. The linear actuators were coupled to their respective joints by tendons made from bicycle hand-brake cables.
WALTER’s arms were coupled by bicycle-brake cables to custom-built linear actuators mounted inside the body. (Left photo courtesy Moultrie News, Mt. Pleasant, SC.)
The left and right grippers were also different (it’s no fun building the same thing twice…), but similar in that they both lacked wrist movement. The right gripper was fashioned from a 10-inch fuse puller, aligned for grasping objects oriented in the horizontal plane. The left gripper was somewhat more complex, constructed from ¼-inch hardwood with two degrees of freedom, and oriented to grasp vertical objects. All gripper joints were tendon-driven by cables spring-coupled to powerful AC solenoids removed from discarded washing machines at the local dump. The gripper solenoids were similarly controlled by toggle switches on the operator’s console.
WALTER’s head could pan left or right approximately 45 degrees either side of center, driven through tendons by a linear actuator mounted in the base to keep the center of gravity low. Load-bearing joints (head pan axis, shoulder, elbows) were fashioned from ball-bearing roller-skate wheels. There was a photocell mounted on top of the head to monitor ambient light conditions, and, of course, the obligatory flashing lamps for eyes and nose. Two microphone ears and a speaker behind the mouth opening provided for remote communications via the telephone handset shown in the photo. (After all, 20 feet is a long way to yell when we have the technology.)
WALTER’s left gripper was tendon–actuated with two degrees of freedom, the right gripper with just one. (Left photo courtesy Moultrie News, Mt. Pleasant, SC.)
The electronics for both the robot and the control console were vacuum-tube based. One interesting submodule was a capacity-operated relay that controlled a touch sensor in the right gripper. The sole purpose of this circuitry was to discourage pulling and prodding by curious onlookers; any stray finger that poked its way into the open claw would be met by a startling and decidedly effective warning snip. The resounding thump of the actuating solenoid only served to accentuate the message.
WALTER met his demise one day in 1967 at the hands of our cleaning lady (bless her heart). I had been experimenting with some Japanese six-transistor portable radios that sold at the time for around five dollars apiece, trying to come up with a low-cost radio control scheme. The idea was to tune each of the four receivers to a blank spot on the AM dial, and use a continuous-tone RF transmitter that could be switched to any one of these four frequencies. Half-wave rectifiers attached to the audio outputs of the individual radios activated sensitive meter relays that in turn controlled the forward, reverse, left, and right power relays in the drive circuitry.
As fate would have it, the unsuspecting maid bravely entered the confines of my bedroom workshop one day when I was not at home and turned on the pre-World-War-II Lewyt vacuum cleaner my dad had rebuilt six times in my brief lifetime. The motor brushes had long since worn down to their springs, which arced across the pitted commutator segments with such intensity that all TV and radio reception for two blocks was blanked out whenever the machine was running. WALTER’s radios responded instantly to this rich broad-band interference, randomly applying power in a mindless fashion to drive motors and steering solenoids alike. The robot lurched forward, twisting and turning, motors whining and solenoids clacking, only to be immediately decapitated with one mighty swing of a Lewyt rug sweeper.
When I got home the vacuum was still running, WALTER was a total loss, our front door was swinging on its hinges, and the maid had vanished, never to return. I subsequently dropped the radio-control objective and decided to pursue full autonomy for the CRAWLER series robots, as discussed in another section.