Editorial Feature

Vehicle Crash Sensors: Road Safety Analysis

In recent years, the demand for more auto safety features and better crash-rating systems has increased, with the increasing number of crashes and the fatalities and injuries related to these crashes. Automobile manufacturers have also begun incorporating more sophisticated technology into their designs.

The introduction of a pre-collision/collision avoidance system is one of the major developments that manufacturers hope will reduce the number of injuries and fatalities on the road.

This technology continuously evaluates the position of a driver as well as any obstacles on the road to prevent damage caused by an accident. The Insurance Institute for Highway Safety have summarised the various types of sensor systems designed for forward collision avoidance technology:

Video courtesy of the Insurance Institute for Highway Safety.

Collision Avoidance Technologies

There are a number of vehicle features that could be considered as collision avoidance technologies. Some of the most common and promising systems are listed below:

  • Forward collision avoidance system – It alerts the driver when the vehicle is getting close to another vehicle in front of it. It employs various sensors such as cameras, RADAR or LIDAR to sense the objects or other vehicles in front of the vehicle. A forward collision warning system provided with autonomous braking can reduce the speed of the vehicle thereby mitigating the effect of collision.
     
  • Adaptive cruise control - Adaptive cruise control maintains the vehicle's pre-set speed. It automatically slows down the vehicle in heavy traffic to maintain a safe gap. Forward-mounted sensors keep track of the distance to the vehicle at the front. The vehicle accelerates to maintain the preset cruise speed as the traffic speeds up.
     
  • Lane departure warning and prevention system – This system employs cameras to track the position of the vehicle within the lane and alert the driver if the vehicle is in danger. Certain systems offer haptic warnings such as seat or steering vibrations, while others provide audible and/or visual warnings.
     
  • Blind spot detection system - This sensor network system monitors the blind spots at the front, side and rear areas of the vehicle. Most of the systems provide visual alerts appearing on or near the side view mirrors upon detecting the blind spot.
    An audible alert is activated when the driver signals a turn, and the vehicle is headed towards the blind spot on the turning side.

Certain systems may also activate the steering controls or brake to maintain the vehicle in its lane.

  • Park assist and backover prevention system -assists drivers to park and back up their vehicles. Rear object detection systems make use of sensors and cameras to enable the driver to look for the objects in the rear side of the vehicle while backing up.
     
  • Adaptive headlight alert drivers to visualize objects better on dark, curved roads. The headlight pivots in the direction of a moving vehicle to illuminate the road ahead based on the vehicle’s speed and steering wheel movement.
     
  • Fatigue warning systems employ sophisticated algorithms to monitor the steering control and other behaviors such as blink duration and blink rate of the driver. This system is designed to warn the driver if it detects drowsiness or inattention.
     
  • Curve speed warning system monitors the vehicle as it approaches bends in the road by using a global positioning system and digital map. Curve speed sensors alerts the driver if the system senses that the vehicle is nearing a curve at an over speed.

How Collision Avoidance System Works?

Pre-collision systems include small radar detectors placed near the front of the car, where the detectors constantly emit high-frequency radar waves.

These waves will then bounce off the closest objects and return to the sensor. Evaluation systems connected to the sensor measures the time taken for the signal to hit the object and bounce back. The system uses this information to determine the position, distance and speed of the vehicle instantly.

Certain systems provide an alarm signal to notify the driver that a collision may happen, while others have pre-crash brake systems that apply additional pressure to the vehicle's braking system to help the driver in slowing down the car and avoiding a potential accident.

Once the airbag control unit determines detects an accident, it transmits a signal to an inflator system. The inflator is activated to produce an explosion of nitrogen gas to fill up the airbag. As the airbag fills up, it bursts through the panel in which it is present and enters the space inside the car to provide a cushioning system for the occupant. As a result, the occupant is prevented from being thrown up forward during the accident. The entire process of airbag protection happens within 25 to 50 ms.

After the crash, the airbag control unit cuts the fuel supply, unlocks the door and suspends the electrical power supply.

Products on the Market – Latest Advancements

Cargolog® Vehicle Safety System

This system developed by Mobitron is a data logger that includes built-in sensors, powered by the vehicle 8 – 48 V DC. It also features GSM/GPRS communication system that provides instant information when a collision is detected.

The key benefits of Cargolog® vehicle safety system include:

  • Improved security for vehicles
  • Avoids unnecessary repair costs on the vehicle.

Airbag Control Unit - SDM C7

Delphi’s Airbag Control Unit is designed for installation in the passenger compartment. It includes crash sensing algorithms that determine direction and severity of the event, and uses occupant status data from its sensors to determine the suitable protection strategy for a specific event. It also offers continuous detection to maintain the integrity of the vehicle safety system.

The key benefits of Airbag control unit - SDM C7 include:

  • Reliable, robust design
  • Provides rear, side and front crash sensing discrimination functions
  • Provides central controller that meets ECE R94 and ECE R95 equivalent regulations.

References

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