Aubertin Derek Nielsen writ 340 May 3, 2013

WRIT 340 May 3, 2013

Automotive Active Safety Systems
Introduction

In the United States in 2011, there were an average of 82 fatal motor vehicle crashes every single day. These crashes resulted in a total of 32,387 deaths; in the same year, there were 5,338,000 motor vehicle accidents overall [1]. These shocking statistics plainly illustrate the often-underestimated danger inherent in driving a car. While these numbers are staggeringly high, fortunately they are in decline. In fact, the number of fatalities in 2011 was the lowest since 1949, despite many more miles being driven in total. Much of this steady reduction in the frequency and lethality of crashes can be attributed to the introduction and widespread adoption of new automotive safety technologies in the past few decades.

Automotive safety technologies can be divided into two basic categories: active and passive safety systems. Passive safety systems are those that reduce the severity of a crash once it has occurred; these include now-ubiquitous technologies such as airbags, seatbelts, and crumple zones. Active safety systems, on the other hand, are engineered to prevent accidents from occurring in the first place. This is accomplished through various methods, including making the vehicle more visible to other drivers, better informing the driver of road hazards, and even taking control of the automobile to prevent an accident. Utilizing technologies ranging from enhanced headlights to radar-based collision avoidance, active safety systems represent a vitally important and rapidly developing branch of automotive engineering.

History of Automotive Active Safety Systems

When Karl Benz patented the automobile in 1886, active safety systems were, unsurprisingly, not part of his design. The original Benz Patent Motorwagen was little more than a motorized carriage, without even a simple headlight for visibility or conspicuity [2]. Interestingly, significant safety improvements over that very first automobile were almost nonexistent for several decades. Even rudimentary passive safety systems only began to be introduced in the early 1930’s, with basic features like safety glass and padded dashboards gradually appearing in passenger cars [3]. It would take many more years before active safety systems began to be introduced in automobiles. With the exception of basic visibility devices such as headlights and mirrors, automotive active safety systems were nonexistent until the dawn of the computer age brought about transformational improvements in safety technology.

Made possible by the power of the miniaturized computer, the introductions of the anti-lock braking system (ABS) in the 1970’s and electronic stability control (ESC) in the 1990’s revolutionized automobile safety. As one of the first safety systems to take corrective action and assist the driver with controlling the vehicle in unstable situations, ESC had an especially significant impact. The Insurance Institute of Highway Safety (IIHS) found that ESC reduces the risk of single vehicle crashes by 40%, and reduces the risk of fatal crashes by a massive 56% [4]. These figures show the tremendous improvement that active safety systems offer, even in cars already protected by passive safety systems. However, as significant as these advances were, they only represent the beginning of the development of active safety systems. New technologies adopted in the last decade are once again causing a paradigm shift in automobile safety, affecting – and potentially saving – the lives of car owners around the world.
Situational Awareness

Improving the driver’s awareness of road hazards is the foundation of safe driving. If a driver is not informed quickly of potential dangers, reacting appropriately to them becomes more difficult and the probability of an accident occurring rises dramatically. Since improving the driver’s ability to anticipate danger has such potential to reduce the frequency and severity of accidents, some of the most effective modern automobile safety technologies function by enhancing the driver’s situational awareness.

Technologies such as the blind spot information system and active steering headlights certainly make driving a safer endeavor, but they have a major shortcoming; the driver alone bears the responsibility for taking action to avoid a dangerous situation. While keeping drivers informed of their surroundings on the road makes a vital contribution to safety, human error often results in an accident despite the frantic warning of active safety systems. This is the impetus behind the rise of driver assistance systems: technologies that not only warn the driver of hazards, but also have the capability to take partial control of the vehicle to prevent a collision.

Rear-end collisions are the most frequently occurring type of accident, and they are also often easily preventable [7]. In many cases, a distracted driver will simply fail to notice that the leading car has slowed or stopped and crash into it. The technology that was developed to prevent this is known as the collision avoidance system. Collision avoidance systems utilize a radar unit mounted in the front of the vehicle to track the distance and speed of the leading car. If the radar senses that the leading car is slowing rapidly, a warning will sound to encourage the driver to brake. If no action is taken and the distance between the two vehicles is decreasing quickly enough to make an accident inevitable, the system will automatically apply the vehicle’s brakes to prevent the collision or at least reduce its impact. It is estimated that collision avoidance would be helpful in 1.2 million accidents per year, including 66,000 crashes resulting in serious or moderate injury and 879 fatal crashes [6]. As effective as collision avoidance systems may be, they only serve to prevent one driver from rear-ending another. Automobiles must rely on another active safety system to protect against more drastic driver errors.

While they may not be as common overall as rear-end collisions, a large proportion of fatal crashes are caused by a vehicle leaving the roadway and colliding with another vehicle head-on [5]. Because of the extreme damage and injury characteristically caused by these collisions, automotive engineers have developed an active safety system that can literally take the wheel to prevent an imminent accident. Lane departure prevention is a driver assistance system that uses cameras mounted in front of the rear-view mirror to monitor lane markings on the road ahead. If the system senses that the car is drifting out of its lane without a turn signal activated, the driver will be warned by a combination of lights, sounds, and vibration in the seat or steering wheel that is reminiscent of driving over a rumble strip. If no corrective action is taken, the lane departure prevention system can take over the vehicle’s electromechanical steering mechanism, turn the steering wheel, and stay in the lane. The IIHS estimated that 7,529 fatal crashes could be prevented every year if all cars were equipped with lane departure warning alone, with far more prevented if lane departure prevention were included as well [5].

While these automotive driver aids undoubtedly have the ability to save lives and reduce injury and property damage, they are not without their limitations. One factor that reduces the effectiveness of active safety systems is the inconsistency of real-world road conditions. For example, a modern lane-keeping system will only be functional on a road with clear lane markings. In a study conducted by the National Highway Safety Association, the lane departure warning system being tested was available 76% of the time on freeways, and only 36% of the time on non-freeways [8]. Some of these safety systems are also very expensive, particularly ones that rely on specialized hardware, such as thermal cameras or radar range finders. The prohibitively high cost limits the impact of some safety technologies because they are initially only available on high-priced luxury models that sell in lower volumes. Finally, there may be some resistance from the public to systems that intrusively warn of hazards or take control of the vehicle to prevent collisions. Active safety systems must be diligently and responsibly designed to minimize false alarms and unnecessary intervention; otherwise, the potentially life-saving technology may simply be deactivated.

With the proliferation of computerized safety systems, the gradually declining cost of components, and the adoption of new technologies such as light detection and ranging (LIDAR), automotive driver aids are simultaneously advancing rapidly in their capabilities and becoming standard on more and more new vehicles. One of the biggest areas for future improvement of driver aids is cost; the more affordable these life-saving systems are, the more cars they will be included in, and the more drivers will benefit from their protection. The effectiveness of existing active safety systems will also continue to improve in the future, as technologies underlying computer vision and artificial intelligence are developed further. For example, a lane keeping system that is only active 36% of the time on non-highways stands to be improved dramatically by more sophisticated image processing software.

Along with the cost reduction and performance improvement of current active safety systems, there is an entirely new category of active safety systems being developed. Known as vehicle-to-vehicle and vehicle-to-infrastructure systems, these technologies capitalize on the recent explosion of Internet connectivity to make driving even safer. One theoretical implementation of these systems would be a “road-train” of cars on a freeway, all communicating constantly with each other. Because of this close cooperation, the vehicles would all travel close together at the same speed, independent of driver input. If the lead car applied the brakes, every car in the train would be instantly notified and could slow automatically. Such a system would improve safety and fuel economy while making freeway travel more convenient. Another promising possibility is a system in which the driver is informed of when upcoming traffic signals will change by the road infrastructure itself, allowing them to safely anticipate when they will have to stop.

While the troubling statistics for automobile accidents are trending downwards, there are still tens of thousands of deaths every year that can be prevented by well-engineered safety solutions. As these technologies become more and more common, there will be an ever-growing group of people that owe their lives to the protective power of automotive active safety systems.