Sumo Bots

Sumo Bots is a building event which was run in the C division in 2011, and is scheduled to be run as a trial event for the B division at the 2015 National Competition. The event consists of building a robot which is able to push another team's robot out of a designated area.

Building the Robot
There are many ways to build the robot. Vex Kits or a similar building kit can be used, as well as a custom-built robot from parts attained on one's own. The method that has had by far the most success is the custom-built robot, since the size of the motor and the wheel configuration can be altered without being constrained by the parts in a kit.

Price
Under the trial event rules, Sumo Bots is a battle of the wallets, in a sense, since most of the components needed to build a good robot can cost a lot of money. If it is possible to salvage parts such as wheels and motors from old robots or RC cars and the like, this cost may be reduced a bit.

Designs
There are many different design possibilities for Sumo Bots.

The Wedge
The wedge, which is essentially a robot that is shaped like a wedge, is the most popular design. Under this design, when the wedge approaches its enemy bot, it can either charge and scoop the other bot right off the competition floor, or, if the other bot tries to charge, it will travel straight up the wedge, and most of the time, fall over.

There are many variations on the wedge that make different designs more or less competitive, beyond making the scoop lower, sharper, and more steep (all of which are obvious though important). These modifications will come by intuition and experience, rather than learning about them by reading.

The Ram
The ram design involves a blunt side, which is used to target other bots abd push them out of the area. This design is not ideal, since a bad wedge could beat it, but if it is able to hit the opposing bot on a non wedged side, it could win.

The Wheels
More wheels mean that less weight rests on the scoop. The scoop does not contribute to pushing power, so weight resting on it is weight wasted. Having more wheels generally means that you will have wheel slip when turning. This happens when the wheel isn't pointing in the same direction as its motion, such as in a four wheeled robot turning about its center. All wheels are pointed forward or backwards, but their direction of travel is tangent to circles centered at the turning point. Either will contribute to significant loss of pushing force; the first for obvious reasons and the second because it will cause the wheel and the ground to engage in kinetic friction instead of the static friction of a wheel rolling on the ground.

The Motors
It is clear that the most powerful motors that are legal under the rules are ideal. This gives the robot more power, and thus more leverage when battling with other robots.

Driving the Robot
More then any other event, it is key that the person operating the Sumo bot has spent lots of time with the Sumo bot and is a skilled operator capable of thinking on their feet so they can react to the actions of their opponent. You can have a Sumo bot capable of knocking anything out of the ring, but if the driver is incapable of directing the bot to harness these abilities, the bot will lose.

Links

 * |Sumo Bots Image Gallery
 * Trial Event Rules (2015)