Application and development trend of modern automotive electronic control technology

1 Overview

In recent years, with the application of electronic technology, computer technology and information technology, automotive electronic control technology has developed rapidly, especially in control accuracy, control range, intelligence and network and other aspects have made great breakthroughs. Automobile electronic control technology has become an important symbol to measure the development level of modern automobiles.

Automotive electronic control systems are basically composed of sensors, electronic controllers (ECUs), drives, and control program software. They are used in conjunction with the mechanical systems on the vehicle (usually fused with subsystems in power systems, chassis systems, and body systems), And use cables or radio waves to transmit information to each other, so-called "electromechanical integration", such as electronic fuel injection system, brake anti-lock brake control system, anti-skid control system, electronic control suspension system, electronic control automatic transmission, electronic power steering Wait. The automotive electronic control system can be roughly divided into four parts: engine electronic control system, chassis integrated control system, body electronic safety system, and information communication system. Among them, the first two systems are directly related to the driving performance of the car.

2 Application of electronic control technology

2.1 Engine electronic control system

The engine electronic control system (EECS) is to electronically control the engine ignition, fuel injection, air-to-fuel ratio, exhaust emissions, etc., so that the engine works under the best working conditions, so as to improve its vehicle performance and save energy 1. The purpose of reducing exhaust emissions.

2.1.1 Electronically Controlled Ignition Device (ESA)

The electronically controlled ignition device consists of a microprocessor, sensors and their interfaces, actuators, etc. The device calculates and judges according to the engine parameters measured by the sensor, and then adjusts the ignition timing, so that the engine can work under the optimal ignition advance angle under different speeds and intake air conditions, and maximize the engine output. Power and torque, reduce fuel consumption and emissions, save fuel and reduce air pollution.

2.1.2 Electronically Controlled Fuel Injection (EFI)

Electronically controlled fuel injection devices gradually replace mechanical or electromechanical hybrid fuel injection systems due to their superior performance. When the engine is working, the device calculates the fuel supply at the optimal working condition pre-stored in the memory after calculation according to the parameters such as the air flow rate, intake air temperature, engine speed and working temperature measured by each sensor according to the pre-programmed program. The control parameters are compared and judged, and the fuel supply is adjusted in a timely manner to ensure that the engine always works in the best state, so that the engine's overall performance is improved under the condition of outputting a certain power.

2.1.3 Exhaust Gas Recirculation Control (EGR)

The exhaust gas recirculation control system is currently an effective measure for reducing nitrogen oxide emissions in exhaust gas. Its main actuating element is a numerically controlled EGR valve, which functions to independently and accurately control the amount of exhaust gas recirculated to the engine. The ECU timely adjusts the circulation rate of the exhaust gas that participates in the recirculation according to the operating conditions of the engine. When the engine is running under load, the EGR valve is opened, a part of the exhaust gas is introduced into the intake pipe and mixed with the new mixture to enter the cylinder for combustion, thereby achieving recirculation, And the exhaust gas sent to the intake system is optimally controlled, thereby suppressing the generation of harmful gas nitrogen oxides and reducing its discharge in the exhaust gas. However, excessive exhaust gas participation in recirculation will affect the ignition performance of the mixture and thus affect the power of the engine. Especially when the engine is idling, low speed, small load and cold, the recirculated exhaust gas will significantly affect the engine performance.

2.1.4 Idle speed control (ISC)

The idle speed control system is realized by adjusting the air passage area to control the intake air flow. The main actuator is the idle speed control valve (ISC). The ECU compares the target speed determined from the input signals of each sensor with the actual engine speed, determines the control amount equivalent to the target speed based on the difference, and drives the actuator that controls the air volume to make the idle speed Stay near the best.

In addition to the above control devices, the engine part uses electronic technology: throttle timing, secondary air injection, engine supercharging, oil vapor evaporation, combustion chamber volume, compression ratio, etc., and has been obtained on some models Application.

2.2 Chassis integrated control system

Chassis integrated control system includes electronically controlled automatic transmission, anti-lock brake system (ABS) and anti-skid system (ASR), electronic steering assist system (EPS), adaptive suspension system (ASS), cruise control system (CCS), etc. .

2.2.1 Electronically Controlled Automatic Transmission (ECAT)

Generally speaking, the speed and torque required by the drive wheels of a car are quite different from the speed and torque provided by the engine. Therefore, a transmission system is required to change the transmission ratio from the engine to the drive wheels. The power is transmitted to the drive wheels so as to be able to adapt to changes in external loads and road conditions. In addition, parking, reversing, etc. are also achieved by the transmission system. It is necessary to coordinate the working conditions of the engine and the transmission system in a timely manner, give full play to the potential of the power transmission system, and achieve the best match. This is the fundamental task of the transmission control system. ECAT can automatically change the position of the gear lever after calculation and judgment according to the engine load, speed, vehicle speed, brake working status and various parameters controlled by the driver, and accurately control the gear ratio according to the shift characteristics to achieve the transmission The best control of the shift, get the best gear and the best shift time. The device has the advantages of high transmission efficiency, low fuel consumption, good shift comfort, good driving stability and long service life of the transmission. The use of electronic technology, especially microelectronic technology, to control the transmission system has become the main method for the current automobile to realize the automatic transmission function.

2.2.2 Anti-lock braking system (ABS) and anti-skid system (ASR)

The anti-lock braking system of the car can sense the instantaneous movement state of the brake wheel, and can prevent the wheel from locking when the car is braked to ensure the optimal slip ratio between the wheel and the ground, so that the car can be controlled on various road surfaces. When moving, the wheels and the ground can reach the longitudinal peak adhesion coefficient and a large lateral adhesion coefficient to ensure that the vehicle does not cause unsafe factors such as lock and drag, loss of steering ability, etc. Maintain directional stability and shorten the braking distance when moving, which effectively improves the safety of driving. It is the most valuable application in automotive safety.

The perfect and expanded function of the automobile brake anti-lock brake system is the drive anti-skid system (ASR), which has many common components. The system uses the speed sensor on the drive wheel to sense whether the drive wheel is slipping. When slipping, the control element reduces the speed through braking or through the throttle to prevent it from slipping. It is essentially a speed regulator, which can improve the longitudinal adhesion between the wheels and the road surface when the speed changes sharply during starting and cornering, provide maximum driving force, improve its safety, and maintain the stability of the car's driving direction .

2.2.3 Electronic power steering system (EPS)

The electronic steering assist system uses electric motors and electronic control technology to control the steering, and uses the power generated by the electric motor to assist the driver in power steering. The system does not directly consume the power of the engine. EPS is generally composed of a torque (steering) sensor, an electronic control unit, a motor, a speed reducer, a mechanical steering gear, and a battery power supply. When the car is turning, the torque (steering) sensor will sense the steering wheel torque and the direction of rotation. These signals will be sent to the electronic control unit through the data bus. The electronic control unit will send data signals according to the transmission torque and the direction of rotation. , To send an action command to the motor controller, the motor will output the corresponding amount of rotating torque according to the specific needs, thus generating power steering. If it does not turn, the system will not work and is in a state to be called. The electronic steering assist system improves the car's steering ability and steering response characteristics, increases the car's maneuverability at low speeds and adjusts the stability when driving. At present, the application of domestic mid-to-high-end cars has helped to turn more.

2.2.4 Adaptive Suspension System (ASS)

The adaptive suspension system can automatically and timely adjust the damping characteristics of the suspension and the rigidity of the suspension spring according to the instantaneous load of the suspension device to adapt to the instantaneous load, maintain the predetermined height of the suspension, and greatly improve the stability and handling of the vehicle Sex and ride comfort.

2.2.5 Cruise Control System (CCS)

Cruise Control (Cruise Control), also known as constant speed driving system, is a control system that allows the driver to ensure that the car travels at a fixed preselected speed without operating the accelerator pedal. In long-distance driving, a cruise control system can be used. The driver does not have to step on the accelerator frequently. The constant-speed driving device will automatically adjust the throttle opening according to the driving resistance to adjust the vehicle speed to be near the constant speed. In case of climbing a hill, the vehicle speed has a downward trend, and the microcomputer control system automatically increases the throttle opening; when descending, the throttle opening is automatically closed to adjust the engine power to a certain speed. When the driver changes gear or brakes, this control system will automatically disconnect. The system can reduce the fatigue of the driver for long-distance driving, which brings great convenience to driving, and at the same time, it can also get better fuel economy.

2.3 Body Electronic Security System

Body electronic safety system includes electronic equipment in the body system, mainly including adaptive headlamp system, car night vision system, airbag, collision warning and prevention system, tire pressure monitoring system, automatic seat adjustment system, seat belt control system Etc., to improve the comfort and convenience of drivers and passengers.

2.3.1 Adaptive headlamp system (AFS)

The adaptive headlamp system can be calculated and judged within the range of headlamp lighting according to the dynamic changes of the body, the operating characteristics of the steering mechanism and other comprehensive factors, so as to determine the current driving status of the car and respond to the low beam of the headlamp. Adjustment, and can automatically open and close and anti-glare when meeting the car. It can effectively reduce the fatigue of the driver when driving on a curved road at night, so that the driver can see the actual road conditions at the turn, so that the driver can have sufficient time to steer and respond to emergency situations, thereby significantly improving the road at night. Driving safety. In Japan, some automakers have standard AFS systems in their high-end cars. For example, Toyota Motor Corporation has adopted a variable headlight "adaptive headlight system for hounds."

2.3.2 Automotive Night Vision System (N VS)

The night vision system is an all-weather electronic eye, which extends the driver's vision range to make the vision range reach 3 to 5 times of the low beam headlight range, and can help the driver to see the lights of the car coming in the distance. Objects on highways in dense fog weather can also be seen from the ground, greatly improving the safety of car driving. The car night vision system works according to the principle of infrared imaging, which belongs to passive infrared imaging technology. The system itself does not emit any signal, but detects the heat of the object in front through a sensor that acts as a camera. The heat energy is concentrated to a detector that can pass through various infrared wavelengths, and the infrared sensitive element of the detector (related to temperature The capacitance of the capacitor changes with the amount of infrared light received), and then converts the radiation into electrical and digital signals in turn, and then displays the image to the driver through the HUD or in-car display. At present, more and more car manufacturers have begun to develop and use car night vision systems, but due to price reasons, major foreign car manufacturers have only used this system in their top luxury models, such as the Hummer H2SUT, the BMW Seven Series sedan, Mercedes-Benz's new S-Class sedan, Cadillac Dewey, etc. With the development of technology and the reduction of production costs of night vision systems, vehicle-mounted night vision systems will be fully popularized.

2.3.3 Airbag (SRS)

The system is a common passive safety device on automobiles at home and abroad. In the event of a vehicle collision, the electric control element will use current to detonate the nitrided gas in the airbag placed in the center of the steering wheel (some are also installed behind the chore box on the instrument panel), which quickly burns to produce nitrogen gas and instantly fills the airbag. The function of the airbag is to form a cushion between the driver and the steering wheel, and between the front seat occupant and the instrument panel, to avoid injury from a hard impact. This device must be used in conjunction with the seat belt, otherwise the effect will be greatly reduced.

2.3.4 Collision Warning and Prevention System (CWAS)

There are many forms of this system, some of them are driving, when the distance between the two vehicles is as small as a safe distance, it will automatically alarm, if you continue driving, it will automatically control the car brake to stop the car at the moment of collision. ; Some are displaying the distance of obstacles behind the car when the car is reversing, effectively preventing the occurrence of a reversing accident.

2.3.5 Tire Pressure Monitoring System (TPWS)

The level of inflation pressure in the car tires directly affects the comfort and safety of the vehicle. If the proper wheel pressure is maintained, tire wear can be reduced, fuel consumption can be reduced, tire damage due to insufficient wheel pressure can be prevented, and the driving stability and safety of the car can be ensured. The tire pressure monitoring system can automatically warn the driver by continuously monitoring the tire pressure, temperature and wheel speed.

2.3.6 Automatic seat adjustment system (AA S)

The device is the product of the combination of ergonomic technology and electronic control technology. It senses the occupant's posture through the sensor and adapts the seat state to meet the passenger's comfort requirements.

In addition to the above control systems, seat belt control systems, fatigue monitoring systems, automatic wiper systems, and intelligent rearview systems have also been applied to some vehicle models.

2.4 Information Communication System

Information communication systems include car navigation and positioning systems, voice systems, information systems, communication systems, etc.

2.4.1 Car navigation system and positioning system (NTIS)

The system can directionally select the best driving route within the city or highway network, and can display a map on the screen to indicate the position of the car while driving, as well as the direction and distance to the destination. This is actually the direction of car driving towards intelligent development, and it can become a driverless car even further.

2.4.2 Voice system (VS)

The system includes voice alarm and voice control. The voice alarm is an abnormal situation in the car, such as fuel temperature, coolant temperature, oil pressure, charging, taillights, headlights, exhaust temperature, brake fluid volume, hand brake, and the door is not closed properly. When the phenomenon or fault is detected by the self-diagnosis system, the computer outputs the information to the speaker or alarm after logical judgment. Voice control is to use the voice of the driver to direct and control certain parts and equipment of the car to perform actions.

2.4.3 Information System (IS)

The system can process the engine's working conditions and other information parameters through the microprocessor, and then output useful information for the driver. In addition to the common contents such as coolant temperature, oil pressure, vehicle speed, engine speed, etc., the displayed information also includes instantaneous fuel consumption, average fuel consumption, average vehicle speed, driving distance, outside temperature, etc. According to the needs of the driver, The information can be displayed at any time.

2.4.4 Communication system (CS)

In this regard, the real use and adoption of the most is the car phone, which is more popular in developed countries such as the United States, Japan, and Europe. The current level is constantly improving. Except for cars and roads, cars and cars, and cars and planes. In addition to the conversation between tools, it can also be connected to the international telephone network through satellites to realize international telephone communication during driving, network information exchange, and image transmission. Now cars have access to information and services anytime and anywhere due to the support of wireless telephone networks, broadband digital signals, the Internet, and other emerging wireless communication technologies.

3 Development trend of automotive electronic technology application

With the development of integrated control technology, computer technology and network technology, automotive electronic technology has clearly developed into three main directions of integration, intelligence and network.

3.1 Integration

The maturity of embedded system, local area network control and data bus technology in recent years has made the integration of automotive electronic control systems an inevitable trend in the development of automotive technology. Integrate the engine management system and automatic transmission control system into the comprehensive control of the power transmission system; integrate the brake anti-lock control system, traction control system and drive anti-skid control system for brake control; through the central chassis controller, Connect the control systems such as braking, suspension, steering, and power transmission through the bus. The controller coordinates the various subsystems through complex control operations to control the driving performance of the vehicle to the optimal level, forming an integrated chassis control system. .

3.2 Intelligent

The development of intelligent sensor technology and computer technology has accelerated the intelligent process of automobiles. Technical issues related to automotive intelligence have been highly valued by auto manufacturers. The concept of "autopilot" in its main technology will depend on the realization of electronic technology. The development of intelligent transportation system (ITS) will be combined with multiple interdisciplinary fields such as electronics and satellite positioning. It can provide the driver with the shortest distance and the best location to bypass the relatively dense concentration of vehicles according to the target data provided by the driver Driving route. It is equipped with an electronic map, which can show the road ahead and use satellite navigation. Obtain weather, traffic flow, traffic accidents, traffic jams and other conditions along the way from global positioning satellites, and automatically screen out the best driving route.

3.3 Networking

With more and more applications of electronic control devices in automobiles, data communication between in-vehicle electronic equipment becomes more and more important. It is very necessary to construct a car electronic network system based on a distributed control system. The rapid exchange of large amounts of data, high reliability, and low cost are requirements for automotive electronic network systems. In this system, each sub-processor operates independently to control and improve the performance of a certain aspect of the car, while providing data services when needed by other processors. The main processor collects and sorts the data of each sub-processor, and generates a vehicle condition display.

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