Step 27: Motor controller
This is a Sabertooth 2 x 25Amp (40Amp peak) robot motor controller for medium sized robots with 2 motors.
Each motor has to be able to go forward and reverse, and switch direction frequently and rapidly without mishap.
The ones I have are 250 Watt 13.7 Amp peak (that is what it says on them). Watts = Amps x Volts and I have 24 Volts so that makes 10.4 Amps using that calculation. Anyhow, well within limits of the Sabertooth.
NOTE: It will handle most forms of abuse and will shut down rather than burn out and so on. It will NOT tolerate having the power supply leads conncted up back to front however - be warned.
Also it has to be able to handle a lot of power as if falling over, motors have to be big enough to allow machine to accelerate fast to bring itself beneath you once again.
Therefore unless you really know what you are doing, designing your own is out of the question.
The sabertooth can handle many types of misuse but you mustn't connect the batteries to it back to front!
The Arduino can send control data to it in several ways but I have chosen a mode called simplified serial mode. The Sabertooth website has a lot of downloadable information on all this.
It isn't exactly low cost but worth the money.