From Garco To The New Bots In Town
FIGURE 10. Second Garco patent application 2C.
78 SERVO 10.2010
back in 1953. There are several brief mentions I found of
Chapman using synchro-selsyns as the position sensors of
his control arm and as the driving motors for his arms.
Synchro-selsyns were traditionally used as position indicator
devices to indicate antenna, shipboard guns and mechanism
positions, and are AC driven and usually don’t have enough
torque to move anything heavy. However, they have been
geared down enough in some applications to deliver a lot
of torque. In this type of application, the driving synchro
must deliver even more force to overcome system gear
friction. They were quite popular military surplus items
several decades ago but are hard to find these days. In my
research, most articles about Garco referred to DC motors
to drive his arms.
Figure 9 shows how Chapman placed his arm in the
‘sending unit’ to control the right arm. The toggle and
pushbutton switches controlled motion of the left arm. The
Popular Science article further describes the robot’s control
systems. “As the joints in the control arm move through six
electric channels, they notify sensing devices in Garco’s
FIGURE 11. Second Garco patent application 2D.
electronic brain that they have disturbed the balance in
many Wheatstone-bridge systems. The disturbance of each
fires an electronic tube which, in turn, fires a relay tube
which actuates one of the five .05 HP motors in Garco’s
right arm. So much for the right arm; Garco’s left arm is
manipulated by 22 pushbuttons, mounted on the case of
the control arm. The pushbuttons — in addition to working
Garco’s left hand and arm — move the robot’s jaws and
lips, increase his height six inches, roll his plastic eyes, and
enable him to bow at the hips.”
Building Garco cost Chapman less than $1,000 for
materials ... “you couldn’t buy it for several times that
sum,” quotes Popular Science. “What father,” Chapman
asked, “would put his own child on the auction block?” At
the ripe old age of eight, Garco was pretty much worn out
and faced retirement in 1961.
The New Bots In Town
Harvey G. Chapman Jr., was certainly a robot innovator
for his day and age. Today — almost 60 years later —
bipedal robots do not require fastening to a base for
