Application of sensors in electronic control of automobile chassis
Abstract: In the new era, the degree of development of electronic technology has become the main factor affecting the direction of automobile development. Sensors are the core components of electronic technology and have been more and more widely used in modern automobiles. One of its functions is that it can be used to improve the brake handling performance, steering performance stability and safety performance of the car. This paper deeply studies the application status of sensors in the electronic control of automobile chassis, and gives a detailed introduction to its future development trend.
1 Introduction
With the development of electronic technology, the electronic level of automobiles is getting higher and higher. The connection between the device of the car chassis control system and the actuator has also entered the stage of electrical signal contact from a simple mechanical connection stage. A good electronic control system of the chassis 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 system in car chassis technology has improved the active safety of the car. Common chassis control systems include the following: traction control, brake control, suspension control, and steering control [2]. The sensor is the core device in electronic technology and a device for signal conversion. Its function is to convert the measured non-electricity signal into an electrical energy signal. It is a key device to promote the comprehensive development of automotive technology. In the automobile chassis electronic control system, the control work is inseparable from the sensor [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 electronic control of automobile chassis
The main function of the car chassis is to allow the car to perform corresponding movements, such as acceleration, deceleration, and steering movements, according to the driver's wishes. The driver expresses his intention by manipulating the steering wheel, throttle, brake pedal and other components in the car.The amount of execution corresponding to these manipulations is the steering angle of the front wheels and the driving torque or braking torque on the wheels. The effect is the longitudinal and lateral forces of the tire. The main factors influencing automobile tire force are road surface adhesion coefficient, wheel normal force, wheel slip rate, and wheel corner angle. The basic principle of automobile chassis control design is to properly adjust and control the wheel slip rate and wheel slip angle under the premise of giving the road surface adhesion coefficient and wheel normal force, so as to achieve indirect regulation of the longitudinal force and side of the tire The purpose of the force is to maximize the adhesion between the tire and the road, so as to improve the active safety, mobility and comfort of the car. The electronic control of the car chassis is a complex system project with multiple systems interacting and interacting with each other. The specific performance is as follows:
(1) The same control system may have multiple actuators and control multiple variables at the same time. (2) The same control target can be controlled independently by different control systems or jointly controlled by multiple systems. (3) The same control target is 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 electronic control of automobile chassis
3. 1 Sensor application in power steering system
In the power steering system, the control object of the sensor is the wheel steering angle. The electronic control of the wheel steering angle achieves the purpose of controlling the power steering system. Common power steering systems are: active front wheel superimposed steering system AFS, active front wheel power steering system ESP and active rear wheel steering system RWS. The sensors used are mainly engine speed sensors, vehicle speed sensors, torque sensors, etc. Through these sensors, the power steering electronic control system realizes light steering and improved response characteristics while increasing output power and reducing engine losses, thereby It also saves fuel.
The working principle of all power steering systems ESP, AFS and RWS is that the driver issues instructions, the sensor detects the condition of the road, and transmits the road condition to the electronic controller and actuator through the network in the form of electrical signals. For example, in the EPS system, this microcomputer-controlled steering assist system has the characteristics of few parts, 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 driving. When driving at a very low driving speed, the steering speed ratio will become larger. At this time, only a small angle is required to turn the steering wheel, the body displacement will change greatly, which will make a lot of work easier, such as Work in parking; the characteristic of this system is that it improves the steering ability and steering response characteristics of the car, and at the same time it also increases the stability of the car at high speed and the maneuverability at low speed. In addition, because EPS can apply an additional torque to the steering wheel as needed, the driver can use the prompt signal of this torque to go to the steering measures. This is the function of this system's steering recommendation. The system is mainly composed of electronic controller, motor and motion transmission mechanism, motor speed sensor, steering torque sensor and steering wheel angle sensor. Other systems are also the same as EPS systems, each playing an important and irreplaceable function.
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's suspension elements, so as to achieve the purpose of achieving vehicle dynamics control. When working, the system integrates the vehicle's movement 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. Thus, control of steering stability, driving stability and vehicle comfort is achieved. The continuous damping control system ADC is composed of 4 control units, CAN, 4 wheel vertical acceleration sensors, 4 vehicle body vertical acceleration sensors and 4 damper proportional valves.
3. 3 sensor application in the electronic control system of driving and braking
3. 3. 1 The sensor is used in the traction control system TCS.
Because the driving torque of the driving wheel of the car is too large, the driving wheel will make a sliding motion relative to the ground. According to the calculation, the safe slip rate of the drive wheel should not exceed 20%. Therefore, we need to control the slip rate of the drive wheel. The system that controls the slip rate of the drive wheel is the traction control system TCS. It is developed on the basis of ABS. In most cars, TCS and ABS share an ECU. The job of the sensor is to sense the slip of the car, and then input the obtained information into the system in the form of electrical signals. , The system analyzes the signal input by the sensor to identify and judge the driving status of the car, so as to take corresponding measures.
3.3.2 The application of sensors in the automotive dynamics electronic stability system ESP.
The ESP system is an active safety system that makes the car more comfortable to maneuver and better direction stability. Its basic working principle is to analyze the input signal of the sensor and perform logical operations to identify the driver's desired motion state for the car ; By adjusting the longitudinal force of the wheels and the driver's expectations of the car, the actual movement state of the car is known. Therefore, it needs more sensors than ABS and TCS to control the yaw motion of the car. This type of sensor recognizes the driver's expectations of the car, including the steering wheel sensor, lateral acceleration sensor, car yaw rate sensor and hydraulic sensor of the master cylinder [4]].
3. 3. 3 The application of the sensor in the automobile anti-lock braking system ABS.
The anti-lock braking system ABS is one of the most important safety components in automotive electronic devices with the longest development time and the fastest application. Its working principle is: control to prevent the wheels from locking when the car brakes, and ensure that the best slip rate between the wheels and the ground (5% -20%) is achieved. In this way, when the car brakes on any road surface, the longitudinal peak adhesion coefficient and the larger lateral adhesion coefficient can be achieved between the wheels and the ground, thereby ensuring that the vehicle will not lock and slip when braking. Unsafe working conditions such as the loss of steering ability reduce the braking distance and improve the handling stability and safety of the car. The functioning sensor is the anti-lock brake sensor, which mainly detects the wheel speed by using the wheel angular velocity sensor, and controls the brake oil pressure when the slip rate of each wheel is 20% to improve its braking performance. The purpose of ensuring vehicle maneuverability and stability [5]. Among them, the wheel speed sensor is a very important device of ABS. Its main job is to provide reliable and accurate wheel speed to the ECU in time. Without the wheel speed sensor, the work of the system cannot be completed. At the same time, the accuracy of the wheel speed sensor will directly affect the work of the system. The wheel speed sensor mainly There are several types of electromagnetic, Hall, and magnetoresistive.
4 The development trend of the application of sensors in the electronic control of automobile chassis
With the development of electronic technology and the automotive industry, the development status of automotive sensors will become one of the key factors affecting the development of automotive high-end, electronic, and automation. The higher the degree of automation of automobiles, the greater the dependence on sensors. Therefore, many automotive electronics industries regard vehicle sensor technology as a key research and development technology project. Because the automobile chassis electronic control system is composed of many systems, the types and number of sensors required are also varied. Then, it is necessary and inevitable to develop new sensors with high accuracy, high reliability and low cost. In order to meet this need, the future development trend of automotive chassis electronic control system sensors will definitely be toward the direction of integration, intelligence and miniaturization; on the basis of basic research, new phenomena, new principles, new developments will be discovered Materials and new processes [7]. The sensors are becoming more precise and the technology content is getting higher and higher, so as to better promote the development of electronic technology and even the automotive industry.
4.1 Introduction to development trends
Intelligent sensor is a kind of sensor with microcomputer, which has multiple functions of detection, judgment, information processing and so on. Compared with traditional sensors, it can correct the measurement data by determining the working status of the sensor, thus reducing environmental factors such as the influence of temperature. Its biggest advantage is that it can fully perceive the status of the driver and passengers, transportation facilities and surrounding environment; can determine whether the driver and passengers are in the best condition, whether the vehicle and people will be in danger, and take corresponding measures in time. The difference is that it uses software to solve the problems, and these problems are difficult to solve in ordinary sensors. For example, to complete the calculation and processing of data, and this intelligent sensor not only has a large range coverage and a large output signal, but also has high accuracy, high signal-to-noise ratio, good anti-interference performance, and many have a self-check function [7] . In the future, if this kind of sensor can be applied to the electronic control system of the car chassis, it will bring a lot of convenience to the driver.
The 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, which reduces the number of car chassis sensors and improves the accuracy of its electronic control system.
The micro-sensor uses micro-machining technology to encapsulate micron-level sensitive components, signal processors, data processing devices, etc. on a single chip. This sensor is easy to integrate, small in size, and inexpensive. Small and precise components can be obvious Improve system test accuracy. At present, this technology has gradually matured, and can produce various miniature sensors such as detecting mechanical quantities, magnetic quantities, and thermal quantities. This sensor is used in the electronic control system of the car chassis, which will greatly optimize many car performances.
4.2 Introduction of 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 foundation for the development of modern sensors.
Another important basis 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 There has been a strong interest in organic materials. They are speculating whether organic materials can be used as functional materials in sensors. This needs further research by experts.
For sensors, the performance of their sensitive components depends largely on the functional materials used. However, the processing technology will also have a certain impact on the performance of the component. Therefore, improving the processing technology will also be a direction for future research. With a variety of new materials such as semiconductors, ceramics, etc. used in sensor sensitive components, many modern advanced processing technologies have also been gradually introduced into automobile sensor manufacturing processes, such as ion implantation technology, integration technology, micro-processing technology, etc. By using these new technologies, new sensitive components 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-electro-mechanical system (MEMS) technology has gradually matured, this technology is developed from the semiconductor integrated circuit technology. Using micro-electromechanical systems, various miniature sensors that can sensitively detect mechanical quantities, magnetic quantities, thermal quantities, chemical quantities, and biomass can be made [8].
For sensors, the performance of their sensitive components depends largely on the functional materials used. However, the processing technology will also have a certain impact on the performance of the component. Therefore, improving the processing technology will also be a direction for future research. With a variety of new materials such as semiconductors, ceramics, etc. used in sensor sensitive components, many modern advanced processing technologies have also been gradually introduced into the manufacturing process of automotive sensors, such as ion implantation technology, integration technology, fine processing technology, etc. By using these new technologies, new sensitive components 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-electro-mechanical system (MEMS) technology has gradually matured, this technology is developed from the semiconductor integrated circuit technology. Using micro-electromechanical systems, various miniature sensors that can sensitively detect mechanical quantities, magnetic quantities, thermal quantities, chemical quantities, and biomass can be made [8].
5 Conclusion
The wide application of electronic technology in automobile technology has made the control system of automobile chassis rapidly developing in the direction of electronic and intelligence, which has led to the emergence of many electronic control systems of automobile chassis, and the sensor is the core device of electronic technology. In addition, more and more sensors are used in automobile chassis. Because of the use of sensors, the brake handling performance, steering performance and safety performance of automobile driving have been greatly improved. At the same time, it also improves the economy and safety of the car. Various electronic steering control systems such as AFS, EPS and RWS are very effective. It 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, through the integration of these new information with the car chassis electronic control system, there will be more new functions and new systems, thus providing sufficient conditions for the development of the automotive industry and basis.
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