> >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

I think that the radial velocity as a vehicle goes around any turn is
zero.
(as if there were a string from the vehicle to the center point of the
turn)
A microwave doppler radar could be used to detect radial (side looking)
velocity.  The radar would see through the ice and still work fine.

Have Fun,
Brooke
brooke@pacific.net