Forward Collision Warning
Forward Collision Warning alerts the driver when the vehicle predicts a high risk of striking a road user or object ahead.
Sensors used
Forward collision warning commonly uses forward Cameras, Radar or both to detect and track objects in the driving path. Some systems add Lidar. Wheel speed and ego-motion data from Positioning and Vehicle Motion support time-to-collision estimation.
The warning depends on path relevance and closing speed, not detection alone. Sensor Fusion covers target association and uncertainty, while Calibration, Cleaning and Sensor Health covers blocked or misaligned sensing.
Risk estimation
Radar can measure range and relative speed, while cameras classify vehicles, pedestrians, cyclists and road geometry. The controller estimates variables such as time to collision and the deceleration needed to avoid impact.
The threshold cannot be based on distance alone. A stationary object far ahead may be urgent at motorway speed, while a close lead vehicle traveling at nearly the same speed may not be.
Warning stages
A typical sequence can include:
- a visual symbol or distance warning;
- an audible and haptic collision alert;
- precharging the brake system;
- dynamic brake support if the driver brakes too weakly;
- automatic emergency braking if risk becomes imminent.
Forward Collision Warning is the alerting function. Brake support and automatic braking are interventions and should be listed separately even when one product package combines them.
Target coverage
Some systems focus on rear-end vehicle conflicts. Others add pedestrians, cyclists, motorcycles, oncoming vehicles during turns or crossing traffic at junctions.
The generic feature name does not establish these capabilities. A specification should identify target type, direction, speed range and darkness performance.
False and missed warnings
Curves, hill crests, metal structures, roadside objects and vehicles entering or leaving the lane can complicate path prediction. A warning may arrive late when a target is hidden, or occur unnecessarily when the driver is already steering around it.
Sensitivity settings normally change warning timing, not sensor reach or braking capability. The driver should not select a late setting to compensate for following too closely.
Automation level
FCW is momentary assistance at SAE Level 0. It does not control speed and does not reduce the driver's responsibility to maintain distance. It can operate alongside adaptive cruise control, but the two functions use different risk thresholds and purposes.