Page 396 - Understanding Automotive Electronics

2735 | CH 11 Page 383 Tuesday, March 10, 1998 1:30 PM

FUTURE AUTOMOTIVE ELECTRONIC SYSTEMS 11

Figure 11.12
Collision Avoidance
Warning System

FPO

If the object is traveling at the same speed as the radar-equipped car and
in the same direction, S = –V, and T is infinite. That is, a collision would never
occur. If the object is stationary, S = 0 and the time to collision is:

R
T = ---
V
Note that this system can give the vehicle speed, which is applicable for antilock
braking systems. If the object is another moving car approaching the radar-
equipped car head-on, the closing speed is the sum of the two car speeds. In this
case, the time to closure is
R
T = ------------
VS
+

UNDERSTANDING AUTOMOTIVE ELECTRONICS 383