Hey guys, my city is planning to build a community robot built over the summer so we can have rookie teams able to do outreach with it in their first year as well as have our community teams grow closer as a whole.
Problem is the electricals, unlike the frame and metal, you cant dumpster dive your schools auto shop waste bin to build half of your bot with. Is there a cheap alternative? Doesnt need to be FRC legal, just needs to be frc motor combatable.
I’d take a look at the Cheap and Dirty control system. Even if you use a different control system, the electrical setup is good enough for light-duty stuff. (You’d have to come up with different fusing to run 40A breakers, and I wouldn’t run your 6-CIM drive on that in a pushing match…but it would drive.)
(Full disclosure: I’m starting at AndyMark in about two and a half weeks.)
The Arduino is adequately ample to do what you want.
You can usually get a Mega2560 from MicroCenter for about $10.
The Mega2560 is capable of running a 3D printer with a RAMPS 1.4 shield to set expections.
Either using some of the many FRC related projects or just bit smashing on your own.
The only place you might find a bit tricky is around encoders.
If you do that look for ICs to count the rotations or a dirt cheap Xilinx or Altera FPGA development board.
If you want to take that up a notch use an Arduino Yun and that will give you WiFi.
A few ideas:
CTRE has a new system out we’re looking at for keeping older robots up and running. For less than the cost of one roborio (probably even PDB) we can run a robot.
http://www.ctr-electronics.com/control-system/hro.html
And here I thought you had already started at Champs! 
I would go with this personally. If it is just for display and demo, there should be no issues running it with the AndyMark gear. Alternatively, you could see if any teams near you are willing to spare an old cRio with the digital sidecar, PDB, and some speed controllers.
Assuming that this will be a simple robot (no vision or crazy sensors) if you can find someone that can code in pbasic or C, you could even use the old IFI control system. They’re inexpensive and many older teams may have boxes of the robot controllers, operator interfaces, radios, and serial port joysticks. If they have those, they probably also have some 883s that they’d be willing to part with.
You’ll never have a radio issue and they can take quite a beating. If you do manage to break one, all you have to do is load your code onto the new controller and drop it in. You won’t even have to re-tether the radio.
We have some sitting around from 2003 and 2004 and they still work flawlessly (even though the robots don’t)
The use of a R/C transmitter to control a robot could give the wrong impression in demonstrations and make the audience think that your robot is nothing more a glorified R/C car than it is a robot(it is an R/C car if you are using this control method).
Although expensive the VEX Cortex, is used by quite a few teams as a Robo-rio replacement. It will simplify your demonstrations as no driver station is necessary, but it still allows a great range of functionality and is similiar to program as a normal frc control system, making it a good learning opportunity for programmers.
Couple the VEX Cortex with a few low cost PWM motor controllers like Sparks or Victor SP’s or old Victor 884/888’s, Talon SR’s and Jaguars with a basic power distribution board ( could be from an old control system or just a small fuse board, depending on how many motors you plan to run) a circuit breaker and a SLA battery and you have a relatively low cost control system, which allows you to utilise as many existing parts as possible while making demonstrating the robot simple and professional
We have tons of old IFI Controllers. PM me if you are interested in anything like that.
http://robotnext.typepad.com/.a/6a00e5521dde2c8833010536ae78b9970b-pi
(full disclosure still applies)
If the robot is going to need programming and be operated without troubleshooters around, then a VEX Cortex is a perfectly good option. (Note that you’re going to need to change genders on the PWM outputs, either by crimping new cables or using both male ends of a Y cable.) However, at $400 there may be alternatives that provide the needed functionality (depending, of course, on the team’s parts pile and willingness to figure out a new platform that may or may not be built with this particular application in mind).
That said, 4901 has a Cheap and Dirty radio that’s seen public use (we ran the Team Cockamamie build on it at Relay for Life–not exactly a high-tech affair) and several drive bases were running them at the AndyMark booth at Championship. While I agree that none of them were true robots in the textbook definition, probably 99.5% of the people were too engrossed in the object being controlled to care–and the other 0.5% that bothered to ask learned the differences between our competition robots and a demo robot. It’s just not that big a deal. 