Sumo Robots

During my undergraduate experience I was a member of PUC-Rio's robotics team, Team RioBotz, that develops and build robots for international and national competitions. A video about the team can be found here. We participated in several national (Winter Challenge and Summer Challenge) and international competitions (RoboGames, Combots Cup and the All Japan Robot Sumo Tournament) with great success.

After 2010 I was nominated the Autonomous Robots Team Coordinator and responsible for the sumo and humanoid robots.

Sumo robot competition is a very challenging and yet rewarding experience. The 3kg robots must be autonomous and able to rapidly find the opponent and push it out of the metal Dojo (arena). They do that using very strong Neodymium magnets to increase the normal force (that could reach over 100kg) and traction. It's a very daunting mechanical end electronic challenge for the robot is constrained to a 200mm x 200mm projected area and limited to 3kg.

The mechanical precision is necessary to perfectly mount the blade used as a wedge (industrial made and usually very hard, ours 58 Rockwell C) and carefully design the gear system to drive the robot. The robots are usually very fast, our uses two 150W 12V RE40 Maxon motors with a 6.8:1 reduction. The Colson wheels are about 65 Shore A to guarantee traction and the magnets hight must be carefully taken into account because if they touch the metal Dojo the robot will get stuck and the motors will stall and electronics will burn due to the current. We used 2 Hyperion 3S 90C LiPo batteries in series to supply the power needed and controlled the system using a 25X50 Dual Channel Sabertooth speed controller and a mbed ARM Microcontroller.
Below are the first two versions of our sumo robot: C3. The second one competed in Tokyo in 2011 and can be visualized partially built.

The 2013 version, C3D4, competed at RoboGames 2013 winning the Gold Medal.
The final version of the sumo used gear instead of timing belts to allow greater reduction ration and to reduce mechanical wear. We decided to add rigid blades (no/little deformation during impact) replacing the old 1mm spring steel sheets and used only two wheels instead of four to ease maneuvering. Five Pepperl Fuchs digital photoelectric sensors were used to find the opponents and four IR sensors were used to detect the Dojo limit lines.

And the newly water jet cut frames

To see C3D4 in action at RoboGames 2013


Gear reduction test


The 3rd place podium at the RoboGames 2012 and our sumo in action in Tokyo in 2011.