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VEHICLE MOTION CONTROL 8

Figure 8.3
(continued)

Speed Response Curves
When a new speed is The curves of Figure 8.3c show the response of a cruise control system
requested, the time with a PI control strategy to a sudden disturbance. These curves are all for the
required for the vehicle same car cruising initially at 60 mph along a level road and encountering an
to reach that speed is upsloping hill. The only difference in the response of these curves is the
affected by the control controller gain parameters.
system’s damping coeffi- Consider, first, the curve that initially drops to about 30 mph and
cient. then increases, overshooting the desired speed and oscillating above and

UNDERSTANDING AUTOMOTIVE ELECTRONICS 265