Easily control robots with omni or mecanum wheels using Sparkfun’s ComMotion Motor Driver Shield. This four-channel shield can control up to four DC brushed motors at once, read their encoders and monitor their current draw. It fits on any RedBoard, Arduino, other development board with an R3 layout.
Each of the two onboard ATmega328P processors is broken out into an FTDI header, and the serial ports can be used for GPS, Bluetooth or LCD modules. This leaves your Arduino serial port free to handle all uploading code.
The ComMotion Motor Driver Shield can be purchased online for $44.95.