CMSC 691R SumoBot Project: Tetanus
Authors: Don Miner, Soumi Ray and Steve Sun
Class: CMSC691R with Dr. Oates
This project was a half-semester long project for the course CMSC691R: Introduction to Robotics
at UMBC taught by Dr. Tim Oates during Spring 2007.
The task was to develop a robot that would compete in SumoBot matches.
Pictures
Videos
The SumoBot Competition
A robot's goal in a SumoBot match is to push the opposing robot out of the ring.
The following restrictions apply to robot contestants:
- The robot must use the Brainstem robot controller provided.
- The robot cannot use forces that are not applied from the three servos provided (e.g., you can't add a fourth or stronger servo).
- The robot must fit in a 15" x 12" x 10" box and not weigh more than two pounds.
Tetanus
Our contestant for this contest is called Tetanus. We chose this name because we had to use rusty nails to build the wood frame (no good nails were available).
Dr. Oates presented an interesting problem in building the robot: the robot must use servos to move. Unfortunately, our servos are not able to rotate in a circular motion, they can only go back and forth. Therefore, we had to figure out a way to get our robot to move.
The most interesting and complex part of Tetanus is the way it moves. It has three independent arms controlled by servos that turn an axle with ratcheting wrenches.
This way, the pulling motion turns the axle, meanwhile, when it returns
into position it ratchets. Each arm also has two free-moving joints that make the motion more fluid. Here is a video of the drive system in action.
The following images are closeups of the drive system; notice the ratcheting wrenches and the arms attached to the servos:
Attached to the axle are a set of remote control car racing tires. They had really good grip on the table and we were really impressed by the traction they gave Tetanus. The following picture is of the tire on the axle:
Another marginally interesting thing about Tetanus is its ramp. Most robots had a long ramp that spanned the entire
length of the robot. We felt that having less contact with the surface would be better. As you can see in some of the
previous images, the orange ramps are shiny at the tips. This is because we filed them down to be extra-sharp and thus we were able to get under many of the robots in the competition (not all).
More time could have been spent on the construction of the frame. It was mostly just crappy pieces of wood nailed together
and we used tie-wraps and electrical tape a little more than we should have.
By the end of the project, most of the screws were becoming loose and more and more electrical tape was needed. In the end though, it managed to stay together, mostly.
Results
Our robot was able to successfully move, although we had a lot of trouble with our Brainstem. Here are two videos
of the robot moving across a table: from the rear and from the top.
Don (blue shirt) and Steve (red shirt) at the final SumoBot competition:
Here is a match we had on the last day of competition versus "Null Terminator," which we won:
Here is a match we had on the last day of competition versus "Atomic Wedgie," which we tied (stalemate):
In the end, Tetanus ended up tied for fifth in the ladder, out of eleven.