>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

Accelerometer

Gyroscope

Fibre optic loop

Anybody care to add the 'etc'

And you'd need a processor to keep track of:-

1.      Change in direction
2.      Rate of change of direction

And it would need an appropriate decision mechanism, a model of the vehicle's
mass/speed etc would be a realistic starting point.

Rgds


Mike

Socrates once gave the advice to "by all means get married... If you
get a good wife you will become happy, if you get a bad one you will
become a philosopher."

Become an Engineer and avoid making this problematic decision.