Tomorrow, Thursday 20th of March, I am driving up to Illinois from the Dallas Area to pick up a steel Sumo ring from www.Lynxmotion.com on behalf of the DPRG club. This ought to be very interesting as I get to see the top secret Lynxmotion facilities, where they make all those great robots. The new Japanese Sumo rules have us using a 1/8" thick ring of steel as the sumo ring for the matches. This allows the use of magnetics and vaccum assist to improve the traction of the robots. Of course you can't just stick a robot in the ring, it still has to move around and attempt to push the other robot out of the ring. This is for the 1 or 3kg 22cmx22cm class of robots. Also www.DPRG.org supports autonomous robotics thus radio control isn't used.