“Crush-free vehicle”
“Active Safety” for safety measures
Full Application of Electronics Technology for Accident Prevention

The concept of vehicle safety is going through a major shift. Up to now “Passive Safety” was the dominant concept to minimize damages in an accident. Besides a passive safety concept, a growing number of automakers are adapting an active safety concept that focuses on accident prevention. Electronics technology plays an important role in realizing “active safety”. Technological advancement in various fields such as sensors, cameras, wireless communications, and in-vehicle networks have made possible realization of accident prevention measures that previously had been difficult with conventional technologies.

Seatbelt requirement laws and increasing use of airbags have reduced the death toll in car accidents, which previously was on the rise with a growing number of cars. But, these measures haven’t led to any reduction in neither the number of auto accidents nor the number of injured in auto accidents. To address this safety issue, automakers are introducing the concept of “active safety” to develop safer cars while reinforcing the existing concept of “passive safety”. The idea is to prevent accidents by predicting signs of potential dangers and responding to them in the early stages. One of the major challenges in applying an “active safety” concept to actual systems is development of technologies that can accurately capture the conditions of vehicle and its surrounding. Particularly, such technologies as sensor, radar and camera that play the role of eyes or ears of vehicles become very important.

Accident avoidance with wireless communication technology

Fig-1. Communication “in-between vehicles” and “between road and vehicle” (Click to enlarge)

Automobile manufacturers are currently developing one of the “active safety” systems that adjust and maintain a safe distance between vehicles. For example, some makers are developing a measurement system that can tells the distance from the cars ahead using dirt resistant milli-meter wave radar that can work in bad weather. Using information from the radar, this system derives the relative distance and velocity between the vehicles. If the distance between the vehicles becomes too short or the speed of the occupant’s vehicle becomes too high, a warning is generated or the speed of the driver’s vehicle is automatically reduced to maintain a safe distance.

For the realization of “active safety”, growing attention is paid on accident prevention systems applied with wireless technology based vehicle-to-vehicle communications. (See Fig.1) For example, the vehicle ahead can send traffic information such as congestion to the vehicles behind. Vehicle-to-vehicle communications can prevent collisions at a blind intersection. Information received through wireless communication system can be sent to drivers in the form of image or voice via a car-navigation system. With such an information system, an automatic breaking system may become available in not so distant future.

Wireless communication technology can also realize an “active safety” system using “road-to-vehicle communications”. For example, one can design a system that receives road information such as the regulated speed limit and gives warning when the driver exceeds the limit.

Video cameras bring sophisticated function to vehicles

Fig-2. White line recognition using a video camera

Along with the growing attention to “active safety”, sensor technology is getting a stronger focus as a key component in developing safety measures. For example, in the US, it has become mandatory to install TPMS (Tire Pressure Monitoring System), which constantly monitors the air pressure of tires by attaching a sensor inside the tires of new cars. The main focus in the development of this system is the sensor, which is mounted in the tire.A wireless communication system transmits the information from the sensor to other driving systems. Efforts to realize a more advanced safety system by capturing driver’s condition through in-vehicle sensors have also been enhanced. As one of such efforts, drowsy driving prevention system is on the way. This system detects signs of drowsiness by recording the focus of driver’s eyes or movements of the eyelid. In this case, the sensor and face recognition technology play key roles in safety system development.

Video cameras also play a significant role in advanced safety systems. A video camera can make more useful information available to drivers in an easy-to-understand form. A system that compensates a driver’s blind spot by camera image has already been introduced in some commercial vehicles. To capture an wider area image, a system using a camera with a fish-eye lens has also been put to practical use. Since this system is equipped with a function that compensates image distortion, it is possible to restore such an image as if the driver himself is looking around. Hence, a video camera is useful by playing a similar role as sensors. Currently various safety measures are in development. Among them are a system that detects vehicle’s behavior by recognizing the position of the white-lines on road and one that confirms the safeness of lane changing by capturing the distance from the vehicle ahead to the vehicle itself using a video camera. (See Fig-2).

High-speed in-vehicle network becomes important

The role of an in-vehicle network increases in significance with the spread of the higher performance safety systems based on multi-media information including images taken by video cameras. An in-vehicle network is an effective system to transmit high-volume multi-media information inside the vehicle. But increasing volume of information may lead to transmission delays. In any safety process, the delay would compromise the reliability of the system and may lead to an irreversible outcome.

In fact, vehicles equipped with multiple in-vehicle cameras are already in the market. We see the upcoming needs of systems that can deal with higher volume of data within a vehicle for multi media data processing. In response to such trends, many makers have started in introducing in-vehicle networks that can effectively handle multi-media information including images and videos. Major standards for in-vehicle network are “MOST” and “IDB-1394”. IDB-1394 is an interface standard based on the IEEE1394 interface that is widely utilized in home AV equipments.