Create Your Own SumoBots Battle

Sumobot Teamwork
SumoBot teamwork. Photo: Maryann Goldman.

There was a lot of fanfare in our house earlier this summer when BattleBots returned to TV. In our home, watching the show turned into a family event, with friendly bets on which bots would continue on in the competition. If you walked by our house during an episode, I’m sure you would have wondered what all the shouting and commotion was about. If you missed out on the excitement, you can read weekly recaps on GeekDad. And if you want to create your own competition, read on to get the scoop on how you can use Lego Mindstorms robotics to create your own robot battles.

Last year, after our FIRST Lego League (FLL) competition season came to an end in November, our team wanted to move forward with more robotics fun and activities. Engaging in a SumoBot competition seemed like a great idea, and we set out to learn all things Sumo.

If you’re not familiar, the art of robot Sumo is modeled after the sport of Sumo. You put two robots, created following a given specification, into a round ring, and the robots try to push each other out. The first robot out loses. The robots can vary in size from fitting inside a 7-by-7-inch cube to much bigger. There may be weight restrictions along with the number of sensors and motors that may be used. The ring, or arena, can vary in size but is often 3- or 4-feet wide and either white with a black outer 2-inch ring or black with a white outer 2-inch ring. The robots will often have tools mounted on them to push or move the other robot out of the ring.

Our team consulted Phil Malone’s SuGo website for guidance and ended up participating in a contest following a set of rules outlined by Appalachian State at the NC Science Festival. Don’t get hung up on the rules; just make sure everyone participating is following the same ones.

So what do you need to get started? Well, you need at least two kids or competitors, two robots, an arena, and some agreed-upon rules. Just make sure to nail down the rules and equipment you are going to use before proceeding.

Sumobot Arena Construction
SumoBot arena construction. Photos: Maryann Goldman.

You can either buy a SumoBot ring or make your own. I was crazy lucky and noticed a round piece of wood sitting on the side of the road. It had obviously fallen off a truck, and it was a little smashed, but it still looked usable and was small enough for me to get in my minivan on my own. My luck continued when I gave my guy the specifications for the ring, and a short time later, I had an awesome SumoBot arena. He trimmed the wood, sanded the platform, and painted it. You don’t have to have woodworking skills or lots of money to spend, though. The ring does not have to be raised off the ground. You could make a ring out of poster board or cardboard, some duct tape, and paint.

Sumobot Designs
SumoBot designs. Photos: Maryann Goldman.

You need to come up with a design for your robot. Do you want your robot to be lightweight, small, and dash around the ring and the opponent quickly? Or, maybe you want your robot to be as large and heavy as possible and attempt to overpower the opponent. Perhaps something in the middle is appropriate. Our team started out with a simple SumoBot and then made modifications. You could use the same robot from your FLL competition. As long as it follows the weight, size, and sensor/motor rules, let your imagination and personal experience guide you. Some of the kids on our team really wanted to test a robot with tracks against a robot with wheels to see which would perform better. The kids followed the TRACK3r building instructions, made a few modifications such as mounting the ultrasonic sensor on the front, and then tested against our simple SumoBot. Our results showed that wheels work better than tracks. TRACK3r kept trying to climb his opponent instead of push him out of the ring.

Sumobots Under Construction
SumoBots under construction. Photo: Maryann Goldman.

Once you have a SumoBot to test out, you’ll need to write a program to run him. Phil Malone’s website has a wonderfully sophisticated program that you can review, dissect, and run to get started. I found it to be of immense help to me, although it was a little too complicated for my kids. I encouraged them to study Phil’s program and to then create their own program keeping in mind several factors:

  1. The robot has to stay moving at all times once the match starts.
  2. The robot has to stay inside the ring.
  3. The robot should try to find and push the opponent out of the ring.
SumoBot Competition
SumoBot competition. Photo: Maryann Goldman.

Our program ended up being a stripped down version of Phil’s program. Move out of the starting box to the left or right, as indicated by the judge. We used two programs to accomplish this; one had a hard-coded left turn, and the other had a hard-coded right turn. The rest of the programs were identical. Start moving forward and stay moving forward until you see the arena boundary (a white line, in our case) or the opponent. If you encounter the white line, back up, turn, and resume moving forward. If you encounter the opponent, speed up and push forward, trying to knock your opponent out. You will also need to keep an eye out for the white line while pushing. It doesn’t sound terribly complicated, but it is. A loop along with an impressive switch (case) statement are required.

SumoEyes from Mindsensors. Photo: Mindsensors.
SumoEyes from MindSensors. Photo: MindSensors.

Your program will need to use the infrared, ultrasonic, or SumoEyes sensor to detect the opponent. Although not genuine Lego, the SumoEyes sensor is a lot of fun to use. It will allow your robot to not only see the opponent when he’s directly in front of you, but also when he’s to the right or left. We were not able to compete with SumoEyes, but we sure did have a lot of fun playing around with the SumoEyes sensor from MindSensors within our own team.

Our FLL team found preparing and competing with SumoBots to be very exciting. The kids really got into the competition of trying to decide on the best SumoBot design. They loved cheering for their SumoBot to win. The whole experience was a pleasant break from the more vigorous FLL season.

Check out this video of our SumoBot in action at the competition this year! 1. 2. 3. Sumo!

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