As a means of transportation for modern people, automobiles have changed people’s lifestyle, promoted the development of social economy and human culture, and become an indispensable means of transportation for society. However, with the continuous increase in car ownership, cars have also brought social issues such as environmental pollution, energy consumption, and traffic safety, among which the issue of road traffic safety is particularly prominent. Every year, about 1.2 million people worldwide die in road traffic accidents, and in recent years, about 100000 people in China have died in road traffic accidents every year, resulting in direct economic losses of billions of yuan.
Due to the continuous occurrence of automobile accidents, they have caused great social harm and caused great attention from countries around the world. Automobile safety has become a global social issue. In order to reduce traffic accidents and casualties, countries have taken a series of measures and achieved good results. Especially in recent years, electronic technology has been widely used in automobiles, equipped with electromechanical products such as ABS, ASR, ESP, SRS, and VDC, and the safety performance of automobiles has been greatly improved. Although the number of cars in China is increasing, the number of deaths in traffic accidents is decreasing, indicating that advanced automotive electronic technology can improve the safety performance of vehicles and reduce the occurrence of traffic accidents.
1、 Contents and influencing factors of automobile safety
（1） Contents of automobile safety
Vehicle safety is generally divided into active safety, passive safety, post-accident safety and ecological safety.
1. Active safety of vehicles
The active safety of the vehicle refers to the ability to control the brake or steering system when the accident is about to happen, and to prevent the accident from happening, as well as the ability to ensure its power, handling stability, driving comfort and normal information when the vehicle is running normally. It can also be divided into driving safety, environmental safety, sensory safety and operation safety.
2. Vehicle passive safety
Passive vehicle safety refers to the ability to protect passengers and pedestrians in the event of an accident, minimizing direct losses. It can also be divided into external security and internal security.
3. Post accident safety accidents
Rear safety refers to the ability of a vehicle to mitigate the consequences of an accident. It refers to whether the consequences of an accident can be quickly eliminated to avoid new accidents.
4. Ecological security
Ecological safety refers to the impact of engine exhaust pollution, vehicle driving noise, and electromagnetic waves on the environment. The content is shown in Figure 1.
（2） Vehicle safety influencing factors
Automobile road traffic accidents are a worldwide disaster, so automobile traffic safety is also a worldwide problem. Road traffic accidents cause casualties and property losses, and also bring huge losses to the national economy. However, the factors that cause traffic accidents are multifaceted, which are comprehensively affected by such factors as vehicle speed, road conditions, vehicle conditions, driver behavior, driver’s cultural quality and natural environment. Among them, people, cars, roads and environmental conditions are the main factors affecting road traffic safety. See Figure 2 for the relationship between them.
In the road traffic system, people are the core of the system, and roads are the foundation of the system. The influence of human factors mainly refers to the character, experience or status of the direct traffic participants. The impact of road factors refers to the route direction, pavement conditions, layout and definition of traffic signals, traffic rules, traffic management measures, etc. The influence of the vehicle itself refers to the vehicle structure and technical conditions. The impact of environmental factors refers to the mental impact of the environment on people (fatigue, reaction ability), the impact on road factors (rain, snow, wind, fog) and the physical impact on vehicles (road adhesion conditions, steering characteristics, etc.). If environmental conditions are included in the range of road impact factors, it can be considered that road traffic safety is mainly related to the “driver-vehicle-road” system. The automobile is the most potentially dangerous link in the system, so applying advanced electronic technology to improve the safety performance of the automobile is an effective way to reduce road traffic accidents.
2、 Application of electronic technology in vehicle driving safety
In recent years, with the rapid increase of car ownership, car safety has become the most concerned issue. In order to ensure the safety of people’s lives and property, the government department has formulated relevant road traffic safety regulations. In order to meet the safety regulations and the requirements of consumers on automobile safety, automobile manufacturers have taken various measures to improve the safety performance of automobiles, among which electronic technology plays a great role. The improvement of automobile safety by electronic technology is mainly reflected in the following aspects.https://www.stoneitech.com/
（1） Active safety electronic technology
The representative electronic control devices of modern automotive active safety electronic technology include anti-lock braking system (ABS), electronic brake force distribution device (EBD), drive anti-skid system (ASR), electronic stability program (ESP), electronic control suspension system, electronic control power steering system, active collision avoidance system, vehicle dynamics control system (VDC), information display system, etc.
1. Anti-lock braking system
Anti-lock braking system (ABS) is an active safety device for preventing wheel lock during braking. During the braking process, the ABS system senses the slip between the wheel and the road surface through the sensor, and the ABS electronic control unit makes the judgment, and adjusts the braking force through the solenoid valve to keep the tire slip rate in an ideal range (10%~20%), so as to ensure that the vehicle has greater longitudinal braking and lateral external force resistance ability when braking, and prevent the possible rear wheel side slip and tail flick, It can improve the directional stability and steering control ability of the vehicle during braking, improve the utilization rate of adhesion coefficient, shorten the braking distance and reduce tire wear. Electronically controlled anti-lock system is one of the effective measures to improve vehicle driving safety.
2. Automobile Drive Antiskid System
ASR controls the slip rate of the vehicle during starting and accelerating within a certain range (5% to 15%) to prevent rapid slipping of the drive wheels and improve the driving force of the vehicle. In the control of ASR, the signal fed back by the wheel speed sensor is processed by the control unit to issue a command to adjust the engine output torque, thereby adjusting the driving torque of the drive wheel. Currently, most ASR devices are implemented by adding some components to the ABS system, which can be seen as an improvement and supplement to the ABS system.
3. Electronic braking force distribution system for automobiles
When a car brakes, the ground conditions on which the four tires are located are often different. For example, sometimes the left front wheel and the right rear wheel adhere to dry cement ground, while the right front wheel and the left rear wheel adhere to water or muddy water. This situation can lead to different friction forces between the four wheels of the car and the ground when braking, which can easily cause accidents such as slipping, tilting, and rollover. The Electronic Brake Force Distribution System (EBD) can automatically adjust the brake force distribution ratio of the front and rear axles based on different axle load transmission during vehicle braking, improving braking efficiency, and cooperating with the ABS system to improve braking stability.
4. Vehicle Electronic Stability Program System
ESP is an abbreviation for Electronic Stability Program in English and is translated into “Electronic Stability Program” in Chinese. This system typically supports the functions of the anti lock braking system and the driving anti slip system. It helps the vehicle maintain dynamic balance by analyzing vehicle driving status information from various sensors, and then sending deviation correction commands to the ABS and ASR. ESP generally requires the installation of steering sensors, wheel sensors, side slip sensors, lateral acceleration sensors, etc. It can monitor the driving status of the vehicle and automatically apply braking force to one or more wheels to keep the vehicle running in the normal lane
5. Electronic control suspension for complete vehicle
Different vehicle driving conditions have different requirements for suspension. Generally, a softer suspension is required for comfort when driving, and a harder suspension is required for stability when cornering and braking. There is a contradiction between the two. In addition, the requirements of vehicle body height are different in different driving environments, and the suspension with constant stiffness cannot meet this contradiction. The ideal suspension should have different spring stiffness and resistance damping under different conditions, which can not only meet the requirements of ride comfort and handling stability, but also achieve the purpose of safe driving. The development of electronic technology makes it possible to design a suspension that can be adjusted within a certain range. This suspension is called electronic control suspension. At present, the most common form is electronic control air suspension. A typical electronic control suspension system consists of electronic control unit (ECU), air compressor, vehicle height sensor, steering angle sensor, speed sensor, brake sensor, air spring element, etc. The system can automatically adjust the performance of suspension components according to the vehicle’s instantaneous driving conditions, that is, detect the vehicle’s running conditions through various sensors. When the suspension electronic control element receives the steering and braking status signals detected by the sensors, it can adaptively process the vehicle’s roll, pitch forward and backward, and automatically adjust the damper damping force, which can prevent the vehicle body from tilting and improve the ground adhesion of the wheels. The system makes the vehicle easier to control and has better handling stability.
6. Electronic power steering system
Electronic Control Power Steering (EPS) is an electronic control system used in the steering system in order to achieve the optimal force required by the steering wheel under various driving conditions. The system automatically adjusts the steering wheel control force under various vehicle speed conditions through an electronic steering microprocessor. Under low speed driving and parking conditions, the driver can flexibly steer with only a small amount of effort. When driving at high speeds, the driver can automatically increase the force to operate the steering wheel.
EPS not only improves driving comfort and steering sensitivity, but also overcomes the drawbacks of high-speed steering “floating”, ensuring the stability and safety of high-speed driving.
7. Vehicle Active Collision Avoidance System
The system is used to assist drivers in real-time monitoring of people, vehicles, and road environments that affect road traffic safety. In emergency situations, the system actively intervenes in driving operations, assists drivers in emergency handling, prevents vehicle collisions, and ensures vehicle driving safety.
8. Integrated control system for vehicle chassis
Vehicle Integrated Chassis Control (UCC) is an advanced integrated system. It connects braking, suspension, steering, and transmission control systems through a central chassis microprocessor. The chassis microprocessor can accept the data transmitted from the sensors of each subsystem and coordinate the control of each subsystem to achieve the optimal overall level of the vehicle and ensure the safety of the vehicle.
9. Vehicle tire monitoring system
The automobile tire is the contact part between the automobile and the ground, which affects the driving force and braking force of the automobile. It plays a very important role in safety. If the tire pressure is insufficient during driving, it will lead to uneven tire wear, increased fuel consumption, and deterioration of stability and handling. It is very easy to cause tire burst and traffic accidents. The automobile tire monitoring system (TMPS) can realize real-time monitoring of automobile tires, and will give an alarm when the pressure is lower than the safe range.
10. Other safety control systems
In order to meet the needs of high speed, safety and comfort of automobiles, more and more advanced electronic technologies are applied to automobiles, such as sleep driving alarm system, driver distraction monitoring system, visual enhancement and night vision system, navigation system, etc., which provide guarantee for safe driving of automobiles.
（2） Passive safety electronic technology
With the development of automobile technology, automobile active safety technology has played an increasingly important role in traffic safety, effectively reducing the occurrence of traffic accidents. However, many traffic accidents are unavoidable in reality, so modern cars also need to be equipped with passive safety systems. The representative electronic device of automotive passive safety electronic technology is the airbag.
Airbag is generally composed of sensor, electronic control unit, gas generator, airbag and clockspring, etc. Generally, gas generator and airbag are combined to form airbag module. When the sensor senses the intensity of the car collision, it transmits the sensed signal to the controller, which receives the signal from the sensor and processes it. When it judges that it is necessary to open the airbag, it immediately sends the ignition signal to trigger the gas generator. After the gas generator receives the ignition signal, it quickly ignites the well to generate a large amount of gas to inflate the airbag. At this time, on the one hand, the passenger’s head and chest are pressed on the air bag and separated from the objects in front of the vehicle. On the other hand, when the human body is in contact with the air bag, the damping of the air bag or the throttle of the exhaust hole on the back of the air bag is used to absorb the kinetic energy generated by the inertia force of the passenger, so as to protect the passenger. The composition of the airbag system is shown in Figure 3.
Airbag is the most effective passive safety device developed recently. It shows great protection effect for passengers in collision accidents. With the development of electronic technology, airbag is gradually developing towards intelligence.
（3） Post-accident safety electronic technology
The safety technology after automobile accident is to ensure the timely rescue of passengers, reduce the loss after the accident, and avoid re-injury. Representative electronic devices include door lock emergency release system, GPS rescue system, etc.
1. Emergency release system of door lock
The door lock emergency release system shall be able to open easily in order to enable the passengers to quickly rescue from the crashed vehicle after the collision accident. Its working principle is that when the collision sensor confirms that a collision has occurred, the system immediately releases the door lock.
2. GPS rescue system
In order to quickly rescue the injured after a collision, the location of the accident vehicle must be accurately determined. The GPS rescue system uses satellite navigation and positioning to quickly determine the vehicle position, shorten the rescue time and reduce the degree of injury to passengers.
3、 Conclusion
With the development of automobile technology and electronic technology, automobile safety technology has gone through the development process from being easy to rescue after collision to reducing damage, and then to accident prevention and prevention. It has gradually developed from passive safety to active safety, to a more humanized and intelligent direction. In the future, cars will become an integrated platform for electronic products, and electronic technology will make cars more safe, comfortable and convenient.
