The net application of force in one direction results in acceleration in the plane - it can't really be characterised as "forward", "backward and so forth, as the whole robot is spinning. However, in a standard configuration an accelerometer is used to determine the speed of rotation, and a light emitting diode is turned on once per revolution, to give a nominal forward direction indicator to the operator. The internal controls implement the commands received from the remote control to modulate the drive to the wheels, typically by turning it off for part of a revolution.