ACC · Adaptive Cruise Control
- Distance
- 70.0 m
- Time headway
- 2.80 s
- TTC
- 14.0 s
- Closing speed
- 18 km/h
Radar detects the vehicle ahead; speed has not been adjusted yet.
The driver selects a speed and following gap. The system tracks the vehicle ahead and adjusts acceleration and braking. When traffic slows, it reduces speed to approach the selected following gap.
◉ Front radar + cameraHow do headway and TTC differ?
Time headway = distance / our speed. TTC = distance / positive closing speed. When speeds match, there is no finite TTC; this does not mean the gap is safe in every situation.
Braking starts at 4 seconds in this teaching scenario: acceleration of −1.25 m/s² reduces speed from 90 to 72 km/h. The selected targets are not production control thresholds.
Read the animation steps
- Radar detects the vehicle ahead; speed has not been adjusted yet.
- The tracking frame identifies the lead vehicle; a positive closing speed reduces the gap.
- Braking reduces our speed, so the gap closes more slowly.
- The speeds match: the distance between the vehicles stops shrinking.
- Both vehicles travel at the same speed; the road keeps moving while their relative positions stay constant.
