A person seated in the driver's seat of a typical car or truck depends on the rear view mirror and two side mirrors to see vehicles approaching from behind. However, vehicles or other objects on either side and slightly behind a car may be in an area that is outside the field of view of the these mirrors. This region is called the vehicle's blind spot. Driver's education classes emphasize the importance of checking for vehicles in the blind spot before attempting to make a lane change. Nevertheless, hundreds of thousands of collisions occur every year during lane changes.
Blind spot detectors, initially developed by Volvo over a decade ago, use radar, ultrasonic, or image sensors to monitor a vehicle's blind spots and alert the driver when other vehicles are present. The alert indication is normally a yellow or red light located in or near the side mirrors that illuminates when a vehicle enters the blind spot between the front seat and back seat, also known as a B-pillar. Some models will provide an additional haptic warning that vibrates the driver's seat and/or steering wheel should they use the turn signals to indicate their intention to change lanes even though there is a vehicle in the blind spot. Detectors operate in such a way that does not take the road limits into consideration. It will give a warning if the driver is moving out of it's lane or if another car is close to sideswiping the driver.
In 2011, Infiniti introduced two models offering a feature called "Blind Spot Intervention". In addition to warning the driver about a vehicle in the blind spot, this system actually helps to prevent the car from changing lanes when a collision is likely to occur. The system applies mild braking to the wheels on the opposite side of the vehicle to pull the vehicle back to its original lane when it determines that changing lanes is likely to cause a collision with a vehicle in the blind spot.
Different manufacturers use various names to describe the blind spot detection system. Ford, Lincoln, and Volvo use the term Blind Spot Information System. Audi calls it Side Assist. General Motors calls it Side Blind Zone Alert. Infiniti calls it Blind Spot Warning.
Other Blind Spot Detection Methods
Multi-radius mirrors having a 40-degree field of view have been a popular option for consumers in Europe and Japan for more than 20 years. But in the US, this cannot be the solution, since government regulations permit only flat mirrors, having a 15-degree field of view. LaneFX offers a relatively inexpensive system that rotates the outside mirrors of the car when the turn signal is activated or on command using a button on the dash to allow the driver to see in the blind spot.
A different blind-spot detection device has been developed by Advanced Technology Products of Toronto, Ontario. The system uses a patented passive infrared sensor technology, which the company claims can sense thermal energy radiating from the tires of a moving vehicle. This temperature difference is used to trigger a flashing red light to warn the driver of the hazard.
Michigan-based Magna Donnelly Corp. has developed panoramic vision displays involving three cameras, which can give an image of both sides and of the back of the vehicle, covering a 70-degree field of view with almost no blind spots. The three cameras replace the exterior and interior rear-view mirrors.