[dtengineering]

I am a high school shop teacher from Vancouver, BC. A project very similar to what you described was developed by a teacher out here in New Westminster, and we duplicated the playing field at our school for use in a metalwork project. It is a great project.

The reason the tethers are such a brilliant idea is that they allow the robot to be built without a battery on board. If you go wireless you are on the hook for the cost of a battery... a good NiMh seven or eight cell battery will set you back fifteen or twenty bucks at least. The tethers are also a great idea because you can control the robot using mechanical switches... if you go wireless you need to have on board circuitry. Typically this is done using H-bridge speed controllers... which while not AS costly as they once were, they certainly are going to be an expense.

My advice would be to attack this project in two steps... first, build a tethered 'bot that meets the requirements for your class. Then look at how to go wireless.

So far the absolute cheapest way to build a wireless mini-sumo robot (10cm x 10cm x 500g) that I have found is to use infra-red remote control. A PIC 16f627a microcontroller (about $3), combined with an L293D motor driver chip (about $2) can drive a Tamiya dual motor gearbox (about $10 in bulk). Hook up a PNA4602M IR receiver (about $2) and program the PIC to receive the IR signal (the Sony IR protocol is quite easy to learn) and use any Sony or Multibrand TV remote control. It's not Radio Control... but it is wireless. Unfortunately I do not have a ready-made means to scale this up to the size and power you require... so I'd suggest build your first robot to run on the tether... then look at developing wireless control later, perhaps on a smaller machine.

You may also want to consider discussing FIRST and VEX with your teacher, or consider other competitions such as the Skills Canada Robotics competition.

Good luck with the project,

Jason