Pressure sensors for Side Crash Detection (SAB)

All front impact sensors for a car work in concert with its supplemental restraint system (SRS). The SRS is a passive system which controls the deployment of airbags and seatbelt restraints. When the front impact sensors sense a crash situation of the car, they send electric signals to the SRS. The SRS then compares this data with the car’s yaw rate and, if needed, sends a signal to deploy the necessary airbags via the airbag pressure switch and seatbelt restraints.

Front and side impact sensors interact similarly with the SRS system, but they measure different things. Whereas a front impact sensor in a car will react to the sudden deceleration of the vehicle, crash detection sensors in the side of a vehicle, like XENSIV’s KP 200 or 204, reacts to pressure changes that occur in the doors. One left front side impact sensor is located inside the driver door, and one right front impact sensor is located in the passenger door. Similarly, the left and right rear side impact sensor locations are inside the rear doors.

When a vehicle sustains lateral impact, the side impact pressure sensor in the affected door(s) observes the change of pressure that happens inside. Within these sensors, a microprocessor analyzes the pressure information and determines whether to send a collision signal to the SRS. If and when that signal reaches the SRS system, the SRS then determines which door(s) to deploy airbags from and sends the appropriate signal. 

Data has shown car doors to be a significant cause of damage during auto accidents – particularly when pertaining to head injuries – even coming before outside objects like trees, signs, or light poles. By cushioning car occupants against the potential force of a vehicle’s doors, front and back side-impact sensors and their corresponding airbags not only increase passenger head safety, but also reduce the risk of injury to the neck, chest, and pelvic regions.

Vehicles typically have right and left front side impact sensors that lie within its “crush zone,” or the area along its front that is most likely to sustain damage in an accident. This proximity to the impact zone positions these front crash impact sensors to instantly deliver accurate signals to the SRS.

Additionally, there front impact sensors detecting the collision of a pedestrian with the front of a car. Two pedestrian protection front sensors sit at opposite ends of a tube along the inside of the car bumper. Pressure forced on the tube by the bumper activates these collision sensors in the car, which signal actuators to lift the hood of the vehicle. The hood’s impact angle minimizes the force of the collision and decreases the risk of serious harm that could stem from a pedestrian directly hitting the engine system.

The benefits of these front-facing impact sensors in a car are clear. They are instant, accurate, and durable; the XENSIV KP 201 sensor, for example, is specially designed to withstand high engine heat by being operational in temperatures up to 125 degrees Celsius. However, they do not present a catch-all solution to passenger or pedestrian safety. Auto manufacturers’ mounting need to address an increase in lateral accidents has brought about innovations in side-impact safety technology and equipment. More than ever before, it is now becoming standard that cars be fitted with right and left rear side impact sensor locations, in addition to front sensors.