Number of
Teeth n
Maximun Drivetrain
Speed
1
2
3
5 mph ( 8 km/h)
10 mph ( 16 kn/h)
15 mph ( 24 km/h)
5 mph ( 8 km/h)
10 mph ( 16 kn/h)
15 mph ( 24 km/h)
5 mph ( 8 km/h)
10 mph ( 16 kn/h)
15 mph ( 24 km/h)
TABLE 1
Maximun Rotational
Velocity to Avoid
Grinding
3,520 rpm
7,040 rpm
10,560 rpm
5,280 rpm
10,560 rpm
15,840 rpm
10,560 rpm
21,120 rpm
31,680 rpm
robot grind instead
of grab the used
dead weights. With
this in mind, it is
possible to generate
a small table with
estimated maximum
weapon speeds to
avoid the grinding
problem. Not going
over the maximum
rotational velocities
shown in Table 1
guarantees that, in
at least 50% of the
hits at full speed, the
tooth will be able to travel at least
1/4”. Of course, these are just rough
estimates because tooth sharpness
and armor hardness also play a role
helping or avoiding dents that bind
with the opponent.
Summary
In this mere 1,600 words, I’ve
managed to grossly simplify the
treatment of this subject in the
Tutorial. The detailed calculations
and a more thorough explanation of
the concepts are available for those
wanting the gory details. SV
C MBAT ZONE’S
GREATEST HITS
Thomas Kenney of MH Robotics ( http://mhrobotics.com/) sent
in his story.
● by Kevin M. Berry
‘One Fierce Lawn Boy.’
Cloud of Suspicion’s bottom
armor is meant to be taken off
between matches to charge
batteries and turn the bot on and
off. As a result, it’s held on with a
measly four 6-32 x .625” screws.
This design flaw allowed Lawn
Boy’s drum to catch onto the inside
of the carbon fiber plate after
cutting through the UHMW that
it’s recessed into. Although the
spray of robot guts was spectacular,
there was no real structural
damage, and the only internal
Before and after photos, brief
description of the fight, and builder’s
name can be submitted to me at
LegendaryRobotics@gmail.com. Or,
if you have an action shot that clearly
shows what’s going on, those are
welcome too! These don’t have to be
current, anything you can (legally)
submit, clear back to the good old
days of wooden bots and iron
builders is fair game.
components that were lost was
one LiPo cell that was sliced through
(and tossed into a LiPo sack right
afterwards!) and the receiver. The
motors that were
disconnected
from their
gearboxes still run
fine; the grazing
impact of
Lawnboy’s
weapon teeth on
the motor cans
had just been
enough to break
the grip of the
blue loctite and
loosen the
screws.” SV
32 SERVO 11.2010
