Page 85 - Build Your Own Combat Robot

Build Your Own Combat Robot
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I0 1.934 amps
R 0.174 ohms
Kv 1,234.6 rpm/volt
Kt 1.097 oz-in/amp

TABLE 4-1 Motor Constants for Figure 4-1

75 percent and it occurs when the motor is spinning at approximately 19,000 RPM.
Maximum output power from this motor occurs when the motor speed decreases to
about 50 percent of its maximum speed and the current is approximately 50 percent
of the stall current. For all permanent magnet motors, maximum power occurs
when 50 percent of the stall current is reached. Motor manufacturers recommend
that motors be run at maximum efficiency; otherwise, motors will overheat faster.

True Story: Grant Imahara and Deadblow
Grant Imahara started his career in robotics as a kid bydrawing pictures of robots
from movies and television. Later, his designs evolved into LEGOs, and then cardboard
and wood. “Onlyrecently,” he laments, “have I had the tools and equipment to build
them out of metal.”
Though Grant got his start as part the Industrial Light and Magic team at Robot
Wars in 1996 (he’s an animatronics engineer and model maker for George Lucas’
ILM special effects company), he is perhaps best known for his creation known as
Deadblow.
Deadblow is a robot with its share of stories. “The best match I ever fought was
against Pressure Drop in season 1.0,” Grant recalls. “I had broken the end of my
hammer off in a previous match against a robot named Alien Gladiator.”
Grant had a spare arm, but, not really expecting to need it, he hadn’t fully
prepared it to mate with the robot. Without the hammer head, he had no weapon,
so a little quick construction work was called for. “‘No problem,’ I thought. I’ll just
drive back to ILM and work on it at our shop. With three hours before the next
match, I figured it would be a breeze.”
Unfortunately, Grant soon uncovered a glitch. “We drove up to the shop and I
started working on the hammer arm. I discovered to myhorror that we were out of
carbide mills, and I had to put two holes in case-hardened steel. After going through
several high-speed steel bits and getting nowhere, I resorted to going through my
co-worker’s desks, trying to find a carbide tool. Finally, I found a tiny 1/16-inch carbide
bit. I took this bit and chucked it into a Dremel tool and painstakinglybored two
3/8-inch holes in the handle of myhammer byhand.”