I have participated at many Lego Sumo competitions. My first one was a total mess. But it got me the experience I needed to build better robots. I even got a “First Place” and a “Second Place”. Usually, there were 2 categories in our competitions: RIS only and Open. Both categories were limited to 12×12 inches and 2 lb weight. The Open category allows the use of more motors and sensors than the ones found in the original RIS kit. I’ll try to show most of my robots below:

Robots at LRGoAA in 2003 & 2004

RISdozer – a RIS only robot

The RIS only category was made for people that had only the original RIS kit, with no extra sensors or motors. The usual robot used the light sensor to detect the ring’s edge and touch sensors to detect the collision with the opponent. These robots would spin in place or drive in straight lines until the edge, turn some degree and drive again until the collision was detected, the they would push their opponent out (if they could…). My robot was the first that used LIDAR in a Sumo competition. It would use touch sensors to detect the ring’s edge and the light sensor, together with the RCX’s IR message sender to detect the opponent. It was working pretty good and by some software glitch it got selected to play the final against the one of the best robots and by luck it won! This was unexpected, but it got me a Lego Spybotics kit. Cool!

PLATFORM – Open category robot

I wanted to build a stealth robot and a robot that would trick the other robots to get on top of it to be easier to be pushed out of the ring. I even built a mechanism that would cover the sensor when the opponent would get on top so the sensor would not get damaged. It didn’t work as expected, but it was a good start for the future robots.

SPY-BLADE – Open category robot

I think I had the only Spybot based Sumo robots. I don’t know why people didn’t try to use them, they were running pretty good. This robot was pretty complicated, as it had a dual feeler that would trigger the single touch sensor at the edge of the ring, the built in motors would slide a electric switch to power regular motors to drive the wheels and I was using the Spybot’s remote in beacon mode to send an IR message to detect the opponent’s range and direction. Powerful, advanced, but a bit slow for the best robots out there.

SPY-DUSTER – Open category robot

Next year I re-built Spy-Blade in a different way, but this time it did not performed as good, as it wasn’t able to detect it’s opponent, but it was more powerful. Some pictures from the event:

PLATFORM-II – open category robot

This time I used an Ultrasonic sensor on the robot and it got the fourth place. The competition was won by Reaktor, a mechanical robot.

RIS only robot

I have re-built RIS-Dozer and also got fourth place at that event (different category). Funniest thing was when a parent said to his daughter “Stay back honey, this one has LIDAR!”


Robots at BrickFest 2003 & 2004


The Sumo competition at BrickFest allowed for a 3 lb robot, so I added a battery box on this one to get closer to the limit. Also the robot had a Beacon so the opponent can use it’s light sensor to detect it. This feature allowed my robot to get second place and in the final mellay was able to push out the first placed robot.


This was my “smart” robot in 2004. It used 2 light sensors to detect the edge and a dual LIDAR sensor to detect the opponent. I used the fact that one of the light sensors would give me lower values than the rest and plugged it in parallel with the other light sensor to detect the IR messages emitted by the RCX. 4 motors and good traction got it the second place (again…).


This was my “muscles” robot. It used 2 light sensors to detect the edge, no opponent detection and lots of power. How much? Well, I used 2 motors to turn electrical switches to drive 2 motors on each side, powered by a battery box (no current limitation). And tons of wheels… 24 to be exact. Hard to turn, but unstoppable in front to front pushing.

Blade vs. Dozer

Hard to say who would win the battle. Most of the time Blade would catch Dozer on the side and push it out. But sometimes, Dozer caught Blade on the side and had his revenge!

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