Home | TCRG articles
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
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:
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.
- 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.
- Go straight
- If you detect the edge of the ring back up and try again.
- Go to 1.
So far I have built 4 sumo robots:
Here are some useful web links:
Building a sumo bot:
CAM: Was my first sumo bot and was built around a 555 timer. It runs forward till it
detects the white ring edge, then trips a relay to reverse a motor for a short while and tries
again. The front wheels turn when it goes backwards, causing it to go a new direction.
Bat and Rhino: These are similar stamp based robots that use CDS cells to detect the
white line and IR emitter / receiver pairs to look for the opponent. The programs for these
robots follow the flow described above in the brains section. You can see pictures of bat,
rhino and other bots at:
Brick: This robot is built with only Lego Mindstorm parts. The motors in the kit are great
with excellent torque. The light sensor is great for detecting the white ring edge. Since it
has no sensors for detecting the opponent, its program just selects a random direction,
goes forward till it finds the ring edge, backs up a little, and repeats. It took me two
evenings to build and much to my dismay, it regularly beats my other robots that I have
put many more nights into building.
Another bot building example:
Rules and a simple bot circuit:
Seattle Robot Society Sumo Rules:
Other sumo rules:
Back to TCRG articles