Application of Sensors in Automobile Chassis Electronic Control

Abstract: Entering a new era, the development of electronic technology has become the main factor affecting the development direction of automobiles. Sensors are the core components of electronic technology and have been increasingly widely used in modern automobiles. One of its functions is to improve the braking performance, steering stability and safety of the chassis. This paper deeply studies the current application status of sensors in automobile chassis electronic control and gives a detailed introduction to its future development trend.

1 Introduction

With the development of electronic technology, the degree of electronicization of automobiles is getting higher and higher. The connection between the device and the actuator of the automobile chassis control system has also entered the stage of electrical signal connection from the simple mechanical connection stage. A good chassis electronic control system can improve the adhesion between the wheels and the ground, thereby improving the safety, power and comfort of the car [1]. The application of electronic control systems in automobile chassis technology has greatly improved the active safety of the car. Common chassis control systems include: traction control, braking control, suspension control and steering control [2]. Sensors are core components in electronic technology. They are devices for signal conversion. Their function is to convert the measured non-electrical signal into an electrical signal. They are key components for promoting the comprehensive development of automobile technology. In the automobile chassis electronic control system, control work is inseparable from sensors [3]. Sensors used for chassis control refer to sensors distributed in the transmission control system, power steering system, suspension control system, braking system, etc. Their functions are different in different systems, but their working principles are the same [4].

2 Theoretical basis of automobile chassis electronic control

The main function of the car chassis is to allow the car to make corresponding movements according to the driver's wishes, such as acceleration, deceleration and steering movements. The driver expresses his wishes by manipulating the steering wheel, accelerator and brake pedal in the car. The execution amount corresponding to these manipulations is the steering angle of the front wheel and the driving torque or braking torque on the wheel, and what really works is the longitudinal force and lateral force of the tire. The main factors affecting the tire force of the car are the adhesion coefficient of the road, the normal force of the wheel, the wheel slip rate and the wheel side slip angle. The basic principle of the car chassis control design is to appropriately adjust and control the wheel slip rate and wheel side slip angle under the premise of given road adhesion coefficient and wheel normal force, so as to achieve the purpose of indirectly regulating the longitudinal force and lateral force of the tire, maximize the adhesion between the tire and the road, and achieve the purpose of improving the active safety, maneuverability and comfort of the car. The electronic control of the car chassis is a complex system engineering in which multiple systems influence and interact with each other. The specific performance is as follows:

(1) The same control system may have multiple actuators and control multiple variables simultaneously. (2) The same control target can be controlled by different control systems alone or by multiple systems together. (3) The same control target can be controlled by different control systems at the same time. (4) Different control systems may share the same sensor or control unit [2].

3 Application Status of Sensors in Automobile Chassis Electronic Control

3.1 Application of sensors in power steering systems

In the power steering system, the sensor controls the wheel steering angle. The purpose of controlling the power steering system is achieved through electronic control of the wheel steering angle. Common power steering systems include: active front wheel superposition steering system AFS, active front wheel power steering system ESP and active rear wheel steering system RWS. The sensors used mainly include engine speed sensor, vehicle speed sensor, torque sensor, etc. Through these sensors, the power steering electronic control system can achieve easy steering operation, improve response characteristics, increase output power, reduce engine loss, and thus save fuel.

The working principle of all power steering systems ESP, AFS and RWS is that the driver issues a command, the sensor senses the road condition, and transmits the road condition to the electronic controller and actuator through the network in the form of an electrical signal. For example, in the EPS system, this microcomputer-controlled steering power system has the characteristics of few components, small mass and small size. When the system is working, if we choose the best transmission ratio, we can get the fastest response: that is, when the car is driving at high speed, the steering speed ratio will become smaller, and the steering force will gradually increase, which will make the car direction more stable and safer to drive. When driving at a very low speed, the steering speed ratio will become larger. At this time, you only need to gently turn the steering wheel at a small angle, and the body displacement will change significantly, which will make many tasks easier, such as parking. The characteristics of this system are that it improves the steering ability and steering response characteristics of the car, and it also increases the stability of the car when driving at high speed and the maneuverability when driving at low speed. In addition, since EPS can apply an additional torque to the steering wheel as needed, the driver can take steering measures based on the prompt signal of this torque. This is the steering suggestion function of this system. The system mainly consists of an electronic controller, an electric motor and a motion transmission mechanism, a motor speed sensor, a steering torque sensor and a steering wheel angle sensor. Other systems, like the EPS system, each play an irreplaceable and important role.

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3.2 Application of sensors in suspension system control

The work of the sensors in the suspension system control is to intervene and adjust the characteristics of the vehicle suspension components to achieve the purpose of vehicle dynamics control. When working, the system integrates the vehicle's motion status and the information detected by these sensors, calculates the optimal damping coefficient of each wheel suspension damper, and then makes work instructions such as automatically adjusting the vehicle height and suppressing changes in vehicle posture, thereby achieving control of handling stability, driving stability and vehicle comfort. The continuous damping control system ADC is composed of 4 control units, CAN, 4 wheel vertical acceleration sensors, 4 body vertical acceleration sensors and 4 damper proportional valves.

3.3 Application of sensors in electronic control systems for driving and braking

3.3.1 Application of sensors in traction control system TCS.

Since the driving torque of the car's driving wheel is too large, the driving wheel will slip relative to the ground. According to calculations, the safe slip rate of the driving wheel should not exceed 20%, so we need to control the driving wheel slip rate. The system that controls the driving wheel slip rate is the traction control system TCS. It is developed on the basis of ABS. In most cars, TCS and ABS share the same ECU. The job of the sensor is to sense the slip of the car, and then input the information obtained into the system in the form of electrical signals. The system analyzes the signal input by the sensor to identify and judge the driving condition of the car, and then take corresponding measures.

3.3.2 Application of sensors in vehicle dynamics electronic stability system ESP.

The ESP system is an active safety system that makes the car more comfortable to operate and has better directional stability. Its basic working principle is to analyze the sensor input signal and perform logical operations to identify the driver's expected movement state of the car; by adjusting the longitudinal force of the wheel and the driver's expectations of the car, the actual movement state of the car is obtained. Therefore, it requires more sensors than ABS and TCS to control the yaw movement of the car. This type of sensor that identifies the driver's expectations of the car includes steering wheel sensors, lateral acceleration sensors, vehicle yaw angular velocity sensors, and hydraulic sensors of the brake master cylinder [4].

3. 3. 3 Application of sensors in automobile anti-lock braking system ABS.

The anti-lock braking system (ABS) is an important safety component in automotive electronic devices that has been developed for the longest time and has been promoted and applied most rapidly. Its working principle is to control and prevent the wheels from locking when the car brakes, and ensure that the wheels reach the optimal slip rate (5%-20%) with the ground. In this way, no matter what kind of road the car brakes on, the wheels can reach the longitudinal peak adhesion coefficient and a large lateral adhesion coefficient with the ground, thereby ensuring that the vehicle will not lock, slip, lose steering ability, or other unsafe conditions when braking, thereby reducing the braking distance and improving the vehicle's handling stability and safety. The sensor that plays a role is the anti-lock braking sensor, which mainly uses the wheel angular velocity sensor to detect the wheel speed. When the slip rate of each wheel is 20%, it controls the brake oil pressure to improve its braking performance and ensure the vehicle's handling and stability [5]. Among them, the wheel speed sensor is a very important component of the ABS. Its main function is to provide the ECU with reliable and accurate wheel speed in a timely manner. Without the wheel speed sensor, the system cannot work. At the same time, the accuracy of the wheel speed sensor will directly affect the work of the system. The wheel speed sensor mainly includes electromagnetic, Hall, and magnetoresistive types.

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4 Development trend of sensor application in automobile chassis electronic control

With the development of electronic technology and the automotive industry, the development of automotive sensors will become one of the key factors affecting the development of high-end, electronic and automated automobiles. The higher the degree of automation of automobiles, the greater the dependence on sensors. Therefore, many automotive electronics industries have made automotive sensor technology a key research and development project. Since the automotive chassis electronic control system is composed of many systems, the types and quantities of sensors required are also diverse. Therefore, it is necessary and inevitable to develop new sensors with high precision, high reliability and low cost. In order to meet this need, the development trend of automotive chassis electronic control system sensors in the future will inevitably be towards integration, intelligence and miniaturization; on the basis of basic research, new phenomena will be discovered, new principles will be adopted, new materials will be developed and new processes will be adopted [7]. This will make sensors more and more accurate and have higher and higher technological content, thereby better promoting the development of electronic technology and even the automotive industry.

4.1 Introduction to development trends

An intelligent sensor is a sensor with a microcomputer that has multiple functions such as detection, judgment, and information processing. Compared with traditional sensors, it can correct the measured data by determining the working state of the sensor, thus reducing the influence of environmental factors such as temperature. Its greatest advantage is that it can fully perceive the status of the driver and passengers, traffic facilities, and information about the surrounding environment; it can determine whether the driver and passengers are in the best condition, whether the vehicle and people are in danger, and take corresponding measures in time. Its difference is that it uses software to solve problems that are difficult to solve with hardware in ordinary sensors. For example, it completes data calculation and processing. In addition, this intelligent sensor not only has a large range and a large output signal, but also has high accuracy, high signal-to-noise ratio, and good anti-interference performance. Many of them also have self-test functions [7]. In the future, if this type of sensor can be applied to the electronic control system of automobile chassis, it will bring a lot of convenience to drivers.

A multifunctional integrated sensor is a sensor that integrates multiple functional sensitive components and multiple sensitive components with the same function. This sensor can detect two or more characteristic parameters or chemical parameters, thus reducing the number of sensors in the vehicle chassis and improving the accuracy of its electronic control system.

Micro sensors use micro-machining technology to encapsulate micron-level sensitive components, signal processors, data processing devices, etc. on a chip. This type of sensor is easy to integrate, small in size, and cheap. Small and precise components can significantly improve the accuracy of system testing. At present, this technology has gradually matured and can be used to produce various micro sensors for detecting mechanical quantities, magnetic quantities, thermal quantities, etc. This type of sensor is applied to the electronic control system of the automobile chassis, which will greatly optimize many performances of the automobile.

4.2 Research methods and directions

The research and development of sensors is inevitable for the development of electronic technology. The basic principles of various sensors are the same, that is, the use of physical phenomena, chemical reactions and biological effects. Therefore, the discovery of new phenomena and new effects is an important basis for the development of modern sensors.

Another important foundation for the development of sensor technology is functional materials. Due to the rapid development of materials science, material manufacturing has reached a very high level, that is, when manufacturing various materials, we can arbitrarily control the composition of the materials. In view of this, we can also design and manufacture various functional materials for sensors. For example, by adding different semiconductor oxides, gas sensors with different properties can be manufactured; optical fibers can be used as sensor materials, which is a major discovery of sensor functional materials; in addition, many experts in automotive electronics at home and abroad have also developed a strong interest in organic materials. They are speculating whether organic materials can be used as functional materials in sensors, which still needs further research by experts.

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For sensors, the performance of their sensitive elements depends largely on the functional materials used. However, the processing technology will also have a certain impact on the performance of the elements. Therefore, improving the processing technology will also be a research direction in the future. With the application of various new materials such as semiconductors and ceramics in sensor sensitive elements, many modern advanced processing technologies have also been gradually introduced into the automotive sensor manufacturing process, such as ion implantation technology, integration technology, micro-machining technology, etc. By using these new technologies, new sensitive elements with high reliability, small size, light weight and stable performance can be manufactured. For example, due to the rapid development of science and technology, micro-electromechanical system (MEMS) technology has become increasingly mature. This technology is developed from semiconductor integrated circuit technology. Using micro-electromechanical systems, various micro sensors that can sensitively detect mechanical quantities, magnetic quantities, thermal quantities, chemical quantities and biological quantities can be manufactured [8].

5 Conclusion

The widespread application of electronic technology in automobile technology has made the control system of automobile chassis develop rapidly in the direction of electronicization and intelligence, which has led to the emergence of many automobile chassis electronic control systems. Sensors are the core components of electronic technology. Automobile chassis are also increasingly using sensors. Due to the use of sensors, the braking and steering performance of the chassis and the safety performance of automobile driving have been greatly improved. At the same time, the economy and safety of the car have also been improved. Various electronic steering control systems such as AFS, EPS and RWS are even more effective. They can make reasonable suggestions to the driver or make necessary corrections to the driver's instructions when necessary. With the further development and improvement of electronic sensor technology, these new information will be combined with the automobile chassis electronic control system through integration, and more new functions and new systems will appear, thus providing sufficient conditions and foundation for the development of the automobile industry.

References

[1] Zhao Fanggeng, Jiang Ding, Zhu Xianmin, 2002. Zhao Huimin. The development of automobile chassis electronic control system. Automotive World. 10.

[2] Chen Zhenfu. 2006. Current status and development trend of automobile chassis control technology. Automotive Engineering. (28): 2.105-113.

[3] Fu Fengji, Dong Liang. Combined application of sensor technology and single chip microcomputer in automobiles. 2005. Beijing Automotive. 6.10-12.

[4] Wang Yun. 2006. Application of sensors in modern automobiles. Journal of Baicheng Normal University. (20): 4 103-105.

[5] Li Jian. 2006. Application status and development of automotive electronic technology. Automotive Applications. 9.

[6] Xiao Qing. 2006. Automotive sensors will usher in a "golden period" of development. Automotive Intelligence. 12/13. 43-48.

[7] Luo Jia. 2006. A brief discussion on the development prospects of automotive electronic technology. Automotive Industry Research. 10.23-26.

[8] Li Yazhou. 2005. The development prospects of automotive electronic technology. Bulk cement. 1.