How could you detect (for computer input) lateral movement from within
 an object when no contact can be made with the ground and there are no
 obstacles around to bounce a signal off of.

For example: How would you detect that the rear end of a car has
 started to slide sideways (on ice) ?  The front wheels are still
 pointed forward (you have not started to turn the wheel to
 compensate).  There are no walls around to bounce a signal off of.
 Assume you have your breaks locked up and therefore cannot use
 comparison of wheel velocities.  Assume also, that you cannot attach
 any sensors to the ground, wheels or be manually activated.  Remember
 that most movement sensors would not be able to tell the difference
 between laterally sliding on ice and a sharp turn.  An optical sensor
 would detect ice but not that your sliding on it.

How would you do it??

Gene