Rear-end accidents are the most common accident types. The importance of keeping sufficient headway for reduction of accidents is recognized by traffic authorities worldwide and is being enforced in an increasing number of countries. Even when sufficient headway is kept a momentary lack of concentration can lead to a situation where a rear-end collision can occur. Mobileye’s Vision-only Vehicle Detection provides a Forward Collision Warning (FCW) in situations where the host vehicle is approaching a preceding vehicle with a high closing rate. This FCW alerts the driver of the critical situation and therefore can prevent or mitigate an accident.
The Forward Collision Warning system is based on Mobileye’s core Vision-only Vehicle Detection technology and provides the driver with a warning in critical situations where a collision is imminent (within up to 3.0 seconds). In addition to vehicle detection in vision only solutions, such as FCW, Mobileye provides active braking products that include fusion with long range radar, currently used on multiple production vehicles.
In 2007 Mobileye launched its own Advance Warning System (AWS) Aftermarket product line which includes Vision-only Forward Collision Warning capabilities.
From 2011 the National Highway Traffic Safety Administration (NHTSA) in the USA is recommending the inclusion of additional safety technologies to the NCAP safety rating. This will include Lane Departure Warning and FCW. Mobileye has been tested by global OEMs and exceeds the NHTSA recommendations, and is currently on multiple production programs for NHTSA compliant Vision-only LDW + FCW features.
Forward Collision Warning detects whether a crash is imminent by computing the ‘Time To Contact’ (TTC) taking into account host vehicle speed, relative speed and relative acceleration. The latter are measured using change of the image size of the target (scale change). In case of a predicted crash, a ‘critical’ warning is given to the driver.
The FCW collision warning ‘track’ can also be used as a trigger message to other vehicle systems to provide pre-crash functionality, such as: secondary restraint system pre-conditioning or brake pre-fill.
Mobileye’s FCW algorithm also takes into account specific scenarios where the system is expected by the driver to have different sensitivity. Such scenarios include the following cases:
- The vehicle in front is standing still – in this case there is a major advantage in using a vision sensor which does not require the target to be moving in order to be acquired. In many cases this is a constant speed scenario with a high closing rate. A warning can be given up to 3.0 seconds before a possible impact.
- The vehicle in front is braking – the braking is first detected by recognizing the target vehicle’s brake lights. This is an acceleration scenario with a lower closing velocity. In this case a warning can be given up to 7 seconds before a possible impact.
- The driver is already pressing the brake pedal – in this case the warning can be given a little later as the drivers response time may be reduced as the brake pedal is already depressed and the time to avoid the collision can be shorter. On the other hand it is important to provide the driver with an alert also at these cases because in such conditions the driver may not notice the slow drift. It is a backup mechanism to alert the driver that the danger has not yet passed.