Heavy Weight Combat Robot - Competition

Competition was very interesting. We didn't do particularly well, but we did make it there with a complete and tested robot (not every team could say that). We also left with a complete and functioning robot (lots of teams couldn't say that).

During testing we discovered that the belt drive used to transfer torque between the motor and spinner was slipping pretty badly. The belt was designed to slip some. During an impact, the spinner stops almost instantaneously. The belt was meant to slip under this condition to protect the motor shaft. We heard from other teams that used the same motor for the same application that their shafts sheared when chained to the spinner. Our concept was good, but the implementation was bad. A belt tensioner was added between testing and competition. It helped, but it didn't fix the problem. We also added a belt dressing which was supposed to make it grip better. In the end it just made the belt disintegrate much faster.

Here's Robespierre right before competition. It looked pretty sweet. The others in our division saw that too. They also warned us that the first tournament would be a "learning experience"... they were right. We went up against two wedge bots. Since the belt was slipping the spinner wasn't able to gain enough kinetic energy to take out the opponents. Just like any vehicle, it can only takes one critical part to cause the whole thing to fail. 99% was good, but that 1% belt prevent it from being amazing. The carbon fiber arms broke off as we had guessed they would. otherwise, the robot received nothing more than a few scratches. We were proud we held up to the beatings delivered by the other robots. Sadly I don't have videos because I was part of the drive team.

A few things we did worked amazingly well. The brushless drivetrain saved a ton of weight. It was a risk that we took because it was an unproven technology in the heavy weight class, but it really gave us an advantage in building our robot. The magnets were also a big boost to performance. Our first match had the magnets on. The robot was firmly planted to the floor at all times. Our last match we didn't have the magnets (the judges were less than amused when a magnet fell off and adhered itself to the arena floor). That match we were jumping up in the air during impacts. It also let us get wedged.

The belly pan got fairly scraped up. I think it looks better with the scratches... it's battle tested!

I'm not really sure where to go with the PROS and CONS list.

PROS
-It breaks stuff.

CONS
-It's only use is breaking stuff

Overall the biggest things we need for the robot are improvements. There are minor fixes that need to be completed before the next competition to make it a real competition. Some are small changes like changing out the belt with something that grips better. Other changes are increasing the ground clearance and making a better magnet system (so they can't fall off during a match).

New Project (finished too) - "Anti-Gravity" Robot

We have a fun little competition at school called the Awesome Things Competition. There aren't really any rules, you just have to make something cool and it gets arbitrarily judged by a few professors who volunteer to see all of the cool projects. If you enter you get $100 to make your project. You can spend more if you want, but most people try to keep it within that budget in the spirit of competition. The winner collects another $100.

My roommate and I were brainstorming ideas for another project we are working on, and we had a funny idea. Could a fan be used to let a robot drive up walls and on ceilings?

We started our design by doing some simple math: addition and subtraction! We added up the weights of the components we wanted on the robot (motors, fan, batteries, chassis, wheels, etc..) and subtracted the thrust from the fan. If our number was negative we were good! We figured the thrust from the fan had to provide the normal force for the robot to drive. We figured any suction effects from the fan would add to a factor of safety to ensure the robot wouldn't drop.

We wanted the project to be super fast to make, so we laser cut all the custom parts from acrylic and used glue to hold them together. We reused transmissions, motors, wheels, and electronics from a robot used in a freshman engineering elective we both took. We only purchased the acrylic sheet, radio, batteries, and fan. Lots of blue tape was used to hold the thing together.

Here's what the robot looked like without all of its hardware. It's kind of cute!

The robot easily held onto the ceiling as 20% throttle when we added some cardboard skirts to create essentially a fancy suction cup. Our dorm room had some silly Christmas decorations because we like to stick things to our ceiling.

We also made a pretty sweet dorm Christmas photo without the need for Photoshop!

The robot ended up "blowing away" the competition. One thing that came up during the project descriptions was how many amps the project drew. It started with one project drawing 2 amps. The next project drew 6 amps and had to have a very interesting power supply to use the small voltage regulators. Then ours came up which could draw 60 amps! This little robot was fun to drive around and led us to victory!

PROS
-Fun to play with
-Loud (it sounds menacing)
-Cheap
-Quick to make
-Won the Awesome Things Competition

CONS
-Loud (We got noise complaints when testing it at 3am)
-Under-powered drivetrain (it's neither fast nor able to push stuff)
-Cludgey electronics (we had to be careful not to short wires or have it fall apart)

Overall this robot was awesome... you might even say the most awesome. At some point if I have free time I'll rebuild it with proper electronics and a nice drivetrain so it moves better.