The Smart Servo Controller for Arduino allows to drive multi servos with a daisy chain connection to your Arduino processor and build robots with powerful servos. This board Integrates a half duplex circuit inside. That means the transmit wire from your UART is connected to all of the AX-12 servos.
Because of the servo can be linked by serial bus, which can link up to 200+ servos. Each unit can feedback its position, rotation velocity, torque, current, motor temperature and so on. It can do rotating all around, and the velocity can be controlled, just act as a gear motor. This feature enables it to work as a motor of wheeled robots, or tracked robots.