As a means of transportation for modern humans, cars have changed the way people live. Automobiles not only promote the development of social economy and the progress of human culture, but also become an indispensable means of transportation in society. However, the existence of automobiles has also caused many negative problems, such as environmental pollution, energy consumption and traffic safety, among which the road traffic safety is the most prominent. The data show that in recent years, China’s annual road traffic accidents have killed about 100,000 people, and the direct economic losses amounted to several billion yuan. The world’s annual deaths from traffic accidents are about 1.2 million, and its direct economic losses are countless. .
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The increasing number of car accidents causing major social hazards has caused the full attention of the national anthem, and car safety has become a global social problem. In order to reduce traffic accidents and casualties, countries around the world have gone through some measures and achieved good results. With the extensive use of automotive electronics technology in automobiles in recent years, equipped with mechanical and electrical products such as ABS, ASR, ESP, SRS and VDC, the safety performance of automobiles has been greatly improved. Although the number of cars in China is increasing, traffic The mortality rate of the accident has shown a downward trend, and naturally, the role of automotive electronics technology is indispensable.
First, the content and influencing factors of car safety
(1) Factors affecting vehicle safety
Car road traffic accidents are a worldwide disaster, so car traffic safety is also a worldwide problem. Road traffic accidents cause human casualties, and property losses have also brought huge losses to the national economy. However, the factors inducing traffic accidents are multi-faceted. It is influenced by factors such 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. The relationship between them is shown in Figure 2.
In the road traffic system, people are the core of the system, and the road is the basis of the system. The influence of human factors mainly refers to the personality, experience or status of direct participants in traffic. The influence of road factors refers to the route direction, road surface condition, the arrangement and clarity of traffic signals, as well as traffic rules and traffic management measures. The impact of the car's own factors refers to the structure and technical conditions of the vehicle. The influence of environmental conditions refers to the mental impact of the environment on people (fatigue, responsiveness), the impact on road factors (rain, snow, wind, fog) and the physical impact on the car (road attachment conditions, steering characteristics, etc.). If environmental conditions are included in the road impact factors, road traffic safety can be considered to be mainly related to the “driver-car-road†system. The car is the most dangerous part of the system, so the application of advanced electronic technology to improve the safety of the car is an effective way to reduce road traffic accidents.
(2) Content of automobile safety
Car safety is generally divided into active safety, passive safety, post-accident safety and ecological safety.
1. Active safety of automotive electronics
The active safety of a car refers to the ability to operate a brake or steering system when an accident is about to occur, to prevent accidents, and to ensure its power, steering stability, driving comfort, and normal information when the car is running normally. It can be divided into driving safety, environmental safety, sensory safety, and operational safety.
2. Passive safety of automotive electronics technology
Passive safety of a car is the ability to protect occupants and walkers from accidents and minimize direct damage. It can also be divided into vehicle exterior safety and vehicle interior safety.
3. Safety after car electronic technology accident
Safety after an accident refers to the ability of a car to mitigate the consequences of an accident. It means whether the consequences of the accident can be quickly eliminated and new accidents can be avoided.
4. Automotive electronic technology ecological security
Ecological safety refers to the effects of engine exhaust pollution, vehicle driving noise and electromagnetic waves on the environment. The content is shown in Figure 1.
Second, the application of automotive electronic technology in vehicle driving safety
In recent years, car ownership has increased rapidly, and car safety has become a major concern. In order to protect people's lives and property, government departments have formulated relevant road traffic safety regulations. In order to meet safety regulations and consumer safety requirements, automobile manufacturers have taken various measures to improve the safety performance of automobiles. A big role. The improvement of vehicle safety by electronic technology is mainly manifested in the following aspects.
(1) Active safety automotive electronic technology
Modern vehicle active safety electronic technology representative electronic control devices include anti-lock brake system (ABS), electronic brake force distribution device (EBD), drive anti-skid system (ASR), electronic stability program system (ESP), electricity Control suspension system, electronically controlled power steering system, active collision avoidance system, vehicle dynamics control system (VDC), information display system, etc.
1. Car drive anti-skid system
The automotive drive anti-skid system (ASR) controls the slip ratio within a certain range (5% to 15%) when the car starts and accelerates, preventing the drive wheel from sliding quickly and improving the driving force of the vehicle. In the control, the signal fed back by the wheel speed sensor is processed by the control unit to issue a command to adjust the output torque of the engine, thereby adjusting the driving torque of the driving wheel. At present, ASR equipment is mostly implemented by adding a part of components in the ABS system, which can be regarded as a perfection and supplement to the ABS system.
2. Car brake anti-lock braking system
Anti-Lock Braking System (ABS) is an active safety device for vehicles that prevents the wheels from locking during braking. The ABS system senses the slippage of the wheel and the road surface through the sensor during the braking process. The ABS electronic control unit makes a judgment and adjusts the braking force by the solenoid valve to keep the tire slip rate within an ideal range (10%). ~20%), to ensure the vehicle has a large longitudinal braking and anti-side force when braking, to prevent possible rear wheel slip, tail, improve the direction and steering of the car during braking The ability to maneuver and improve the adhesion coefficient utilization, shorten the braking distance and reduce tire wear. The electronically controlled anti-lock braking system is one of the effective measures to improve the driving safety of vehicles.
3. Automotive electronic technology stability program system
ESP is the abbreviation of English ElectronicStabilityProgram, translated into Chinese as "electronic stability program". This system is usually used to support anti-lock braking systems and to drive anti-skid systems. It helps the vehicle maintain dynamic balance by analyzing the vehicle's driving status information from each sensor and then issuing correction commands to ABS and ASR. ESP generally requires the installation of steering sensors, wheel sensors, side-slip sensors, lateral acceleration sensors, and so on. It monitors the car's driving status and automatically applies braking force to one or more wheels to keep the car running in the normal lane.
4. Automotive electronic brake force distribution system
When the car is braking, the ground conditions on which the four tires are attached are often different. For example, sometimes the left front and right rear wheels are attached to the dry concrete floor, while the right front and left rear wheels are attached to the water or mud. This can result in four wheels and the ground when the car is braking. Friction is not the same, it is easy to cause slipping, tilting and vehicle rollover accidents when braking. The electronic brake force distribution system (EBD) can automatically adjust the braking force distribution ratio of the front and rear axles according to the difference in axle load transfer caused by the vehicle braking, improve the braking efficiency, and improve the braking stability with the ABS system.
5. Automotive electric control power steering system
The electronically controlled power steering system (EPSElectronicControlPowerSteering) is designed to achieve the optimum value of the force required to drive the steering wheel under various driving conditions, while the steering system uses an electronically controlled system. The system automatically adjusts the steering wheel's operating force through an electronically controlled steering microprocessor at various speeds. At low speeds and when the vehicle is placed, the driver can flexibly turn with less force, and at high speeds, the force to operate the steering wheel can be automatically increased.
EPS not only improves the driving comfort and steering sensitivity, but also overcomes the shortcomings of high-speed steering "floating", ensuring the stability and safety of high-speed driving.
6. Automotive electronically controlled suspension
Different driving conditions of the car have different requirements for the suspension. In general, a soft suspension is required for comfort, and a hard suspension is required for stability when turning and braking. There is a contradiction between the two. In addition, the different environments of the car are different for the height of the car, and the suspension with the same stiffness cannot meet this contradictory demand. The ideal suspension should have different spring stiffness and resistance damping under different conditions, which can meet the requirements of ride comfort and handling stability, and achieve safe driving. The development of electronic technology has made it possible to design a suspension that can be adjusted within a certain range. This type of suspension is called an electronically controlled suspension. At present, it is more common in the form of an electronically controlled air suspension. A typical electronically controlled suspension system consists of an electronic control unit (ECU), an air compressor, a vehicle height sensor, a steering angle sensor, a speed sensor, a brake sensor, and an air spring element. The system automatically adjusts the performance of the suspension assembly according to the vehicle's instantaneous driving conditions, that is, the vehicle's operating condition is detected by various sensors. When the suspension electronic control unit receives the steering and braking status signals detected by the sensor, It can adaptively handle the roll, forward and backward of the vehicle, and automatically adjust the damping force of the damper to prevent the car body from tilting and improve the ground adhesion of the wheel. The system makes the car easier to control and has better steering stability.
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7. Automobile integrated chassis control system
The Automotive Integrated Chassis Control System (UCC) is an advanced integrated system that connects the braking, suspension, steering, and drive train control systems through a central chassis microprocessor that accepts each sub-system. The data sent by the system sensor is coordinated and controlled by each subsystem to optimize the overall level of the vehicle and ensure the safety of the vehicle.
8.Automobile collision avoidance system
The system is to assist the driver of the vehicle to monitor the environment of people, vehicles and roads that affect road traffic safety. In the critical situation, the system actively interferes with driving and driving, assists the driver in emergency treatment, and prevents the occurrence of automobile collision accidents. Car driving safety.
9.Automobile tire monitoring system
Car tires are the contact parts between the car and the ground, affecting the driving force and braking force of the car. It plays a very important role in safety. If the tire pressure is insufficient during driving, the tire will wear unevenly, the fuel consumption will increase, and the stability and maneuverability will be deteriorated. It will easily cause the tire to burst and cause traffic accidents. The Automotive Tire Monitoring System (TMPS) enables real-time monitoring of automotive tires and alerts when the pressure is below safe.
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 warning systems, driver distraction monitoring systems, visual enhancement and night vision systems, navigation systems, etc. Safe driving provides a guarantee.
(II) Safety after the accident, automotive electronics
The safety technology after a car accident is to ensure that the occupants can help in time and reduce the loss after the accident to avoid further injury. Representative electronic devices include door lock emergency application systems, GPS rescue systems, and the like.
1. Door lock emergency release system
Door lock emergency release system After the vehicle collides, in order to enable the occupant to quickly rescue from the crashed vehicle, the door should be easy to open. The working principle is that when the collision sensor confirms that a collision has occurred, the system immediately applies the door lock.
2.GPS rescue system
In order to quickly rescue the injured person after the collision of the vehicle, the location of the accident vehicle must be accurately determined. The GPS rescue system uses satellite navigation and positioning to quickly determine the vehicle's position, shorten the rescue time, and reduce the damage of the occupants.
(3) Passive safety automotive electronic technology
Automobile active safety technology has played an increasingly important role in traffic safety with the development of automobile technology, which naturally reduces the occurrence of traffic accidents. However, in reality, cars still inevitably have many traffic accidents, so it is necessary to equip passive safety systems. Airbags have become representative electronic devices in automotive passive safety electronics.
The airbag is generally composed of a sensor, an electronic control unit, a gas generator, an airbag, and a freewheel. The gas generator and the airbag are usually combined to form an airbag module. The airbag is generally composed of a sensor, an electronic control unit, a gas generator, an airbag, and a freewheel. The gas generator and the airbag are usually combined to form an airbag module. When the sensor senses the collision strength of the car, the signal is transmitted to the controller, and the controller receives the signal of the sensor and processes it. When it judges that it is necessary to open the airbag, it immediately sends an ignition signal to trigger the gas generator, and the gas generator receives After the ignition signal, the rapid ignition well generates a large amount of gas to inflate the airbag. At this time, on the one hand, the head and chest of the occupant are pressed against the airbag to be separated from the object inside the vehicle. On the other hand, when the human body is in contact with the airbag, the damping of the airbag or the venting of the airbag on the back of the airbag is used. The function is to absorb the kinetic energy generated by the inertial force of the occupant to protect the occupant. The composition of the airbag system is shown in Figure 3.
Airbags are the most effective passive safety devices newly developed. They show great protection for occupants in collision accidents. With the development of electronic technology, airbags are gradually moving toward intelligent direction.
With the development of automotive electronics technology and electronic technology, automotive electronics technology has evolved from passive safety to active safety from the ease of rescue to the reduction of damage, to the prevention and prevention of accidents. It has become more user-friendly and intelligent. Turn. Electronic technology will make cars safer, more comfortable and more convenient, and future cars will become a comprehensive platform for electronic products.
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