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Sumo Robot Building Hints

By Rand Whillock

Building an autonomous sumo robot can be easy. You need to assemble a few key parts:

Power train - You need good gear motors. I look for gear motors everywhere (Ax man surplus stores around the Twin Cities area are a good source). Lego gear motors are also pretty good.

Body - Most sumo bots are built wedge shaped. Build it tough, it will take a beating.

Power - Select a reliable power source. I use 6-9 volt packs of rechargeable batteries.

Sensors - Detecting the edge of the ring is a must. I have used CDS cells, IR receiver and transmitter pairs and mechanical switches to detect the ring edge. Detecting the opposing robot is optional. You can use IR, acoustic or even mechanical bump switches.

Brains - The brains of a sumo bot can be quite simple. A basic control flow can be:

  1. Select a direction to go. This can be based on detecting the opponent, picking a random direction, or just turning a little bit at a time one direction.
  2. Go straight
  3. If you detect the edge of the ring back up and try again.
  4. Go to 1.
This control flow can be hardwired or programmed into simple microcontroller such as a basic stamp. Smarter controllers will let you do complex actions based on sensor inputs.

So far I have built 4 sumo robots:

Here are some useful web links: Building a sumo bot: http://www.cercot.demon.co.uk/SUMO/BUILD.HTM
Another bot building example: http://www.ece.concordia.ca/~dave/project/intro.html
Rules and a simple bot circuit: http://www.robotgames.com/sumo.htm
Seattle Robot Society Sumo Rules: http://www.seattlerobotics.org/nwrs/index.html
Other sumo rules: http://members.tripod.com/rksingh21/sumo.htm

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