Controlling 2 DC motors for power and one stepper motor for steering


I am building a robot using a small radio flyer wagon. I have two 12 Volt DC motors for power that are connected to the arduino via a motor shield. I'm having trouble executing turns by spinning one wheel in reverse and the other forward. I'm thinking of using a stepper motor to steer the unpowered back wheels. How can I control the existing two motors and a stepper motor. The specifications on the motor shield indicate that it can only control two regular DC motors or one stepper motor. I'm looking for some direction and ideas.

Thank you,

Stephen Jung

Are you using this motor shield? You'll need more than one such controller if you want three motors. However, what is the problem with reversing one motor? Also, why a stepper? A servo would probably be a better choice for steering, with the added benefit of not needing any additional drivers.

Hi StephenJung, Is this a 4 wheeled bot? I have never made a 4 wheel bot, because of the trouble trying to turn it?

What current do your motors need? quite a bit I would think, perhaps more then your driver can give is the driver shield based on the L293/298 etc. It loses about 2 volts, and more on higher currents...

Not sure what a flyer wagon is, can you give us some more details, also a schematic and your code, we need to see such things in order to help you more.

See my bots at: under Electronics..