The optimization of the cannon was a resounding
success, and it all came from an understanding of the
air cannon physics that allowed us to pinpoint the
biggest areas of improvement in the original design.
Of course, there was even more we could do; we still
want to automatically actuate the ball valve to have a
proper robotic air cannon, and devising the quickest
method to open the valve is another way to maximize
performance. When it comes to robotics and just
about any project, there is always room for
Please remember, everyone! A compressed air
cannon is even more dangerous than a Red Ryder B.B.
Gun, and it can do a lot worse than put your eye
out. We took numerous safety precautions. Don’t try
this at home without taking those proper precautions.
That would be a terrible way to end up on the
Since we were inspired to revisit some projects
for optimization this time, we also took the
opportunity to gift our 60 lb combat robot,
Troublemaker with a new weapon. Or, rather an
optimized version of its old weapon. When we first
designed Troublemaker’s horizontal spinner, we were
focused on avoiding having the force transferred back
into our own bot. To that end, the spinning
mechanism itself is belt driven, and on the ends of
the spinner we used tethered weights. The design
achieved its purpose in that we successfully avoided
having Troublemaker destroy its own weapon
mechanism. However, the tethered weights presented
a problem that we hadn’t quite expected: The tethers
were destroyed in every competition.
While it was a little tough to see what precisely
happened during the fast-paced matches, we
eventually deduced that the weak points were the
stoppers that we used at the end of the weights. For
the tethers, we used steel cables that we threaded
through a hole in the center of our weights. We
looped the end of the cable back around and clamped it
together as a stopper.
The clamps, however, were not rated for heavy lifting.
The centripetal force the stoppers needed to exert on the
spinning weights — combined with some well-placed hits on
other robots (or the arena) — were all that was needed to
shear off the clamps.
We’ve chronicled in the pages of SERVO Magazine our
efforts at an alternate weapon design: some titanium claws
that wouldn’t get sheared off. The claws worked well
enough, but they lacked the impact of the spinning
weights. So, we devised a new design that would keep the
weights on the bot.
Instead of steel cables for tethers, we opted for heavy
duty chain. Since it took us a long time to cut through with
a pneumatic disc cutter, we figured it would make it
through three minute matches just fine. To attach the
weights to the chain, we opted for shackles and eye bolts
that were also rated for heavy duty lifting. The new design
was now a bit more modular which would allow us to
replace damaged parts easily.
It was a thrill to get Troublemaker’s spinner back to its
former hard hitting glory. Now, we just had to replace the
aging stiffening belt to get it to spin up quickly again.
When it comes to optimizing bots, there are always
more gifts to give. SV
SERVO 12.2015 59
GIFTING TROUBLEMAKER A NEW WEAPON.
THE WEIGHT IS OVER.