With the development of electronic technology, the degree of electrification of automobiles is also increasing. The connection between the device and actuator of the automotive chassis control system has also entered the electrical signal connection stage from a 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 vehicle. The application of electronic control systems in automotive chassis technology has greatly improved the active safety of automobiles.
Common chassis control systems include traction control, brake control, suspension control, and steering control. Sensors are the core devices in electronic technology, which are devices for signal conversion. Its function is to convert the measured non electrical signals into electrical signals, and it is a key device that promotes the comprehensive development of automotive technology. Sensors are essential in the electronic control system of automotive chassis. Sensors used for chassis control refer to sensors distributed in transmission control systems, power steering systems, suspension control systems, braking systems, etc. Their functions are different in different systems, but their working principles are the same.
Fundamentals of Electronic Control Theory for Automotive Chassis
The main function of a car chassis is to enable the car to make corresponding actions according to the driver’s wishes, such as acceleration, deceleration, steering, etc. Drivers express their will by manipulating internal components such as the steering wheel, accelerator, and brake pedal. The corresponding amount of execution for these maneuvers is the steering angle of the front wheels and the driving or braking torque on the wheels. What really works is the longitudinal and lateral forces of the tire.
The main factors that affect the force on car tires include road adhesion coefficient, wheel normal force, wheel slip rate, and wheel side slip angle. The basic principle of automotive chassis control design is to adjust and control the wheel slip rate and wheel lateral angle appropriately, given the road adhesion coefficient and wheel normal force, in order to indirectly adjust the longitudinal and lateral forces of the tire, maximize the adhesion between the tire and the road, and achieve the goal of improving the vehicle’s active safety, mobility, and comfort. Automotive chassis electronic control is a complex system engineering with multiple system interactions, specifically manifested as:
(1) The same control system may have multiple actuators controlling multiple variables simultaneously.
(2) The same control objective can be individually controlled by different control systems or jointly controlled by multiple systems.
(3) The same control objective is simultaneously controlled by different control systems.
(4) Different control systems can share the same sensors or control units. https://www.slw-ele.com/
The Application Status of Sensors in Automotive Chassis Electronic Control
The Application of Sensors in Power Steering Systems
In the power steering system, the control object of the sensor is the wheel steering angle. By electronically controlling the steering angle of the wheels, the purpose of controlling the power steering system is achieved. Common power steering systems include active front wheel overlay steering system AFS, active front wheel power steering system ESP, and active rear wheel steering system RWS. The sensors used mainly include engine speed sensors, vehicle speed sensors, torque sensors, etc. The power steering electronic control system uses these sensors to achieve steering control, improve response characteristics, increase output power, reduce engine consumption, and thus save fuel.
The working principle of all power steering systems ESP, AFS, and RWS is that the driver issues commands, sensors sense road conditions, and transmit the road conditions in the form of electrical signals to electronic controllers and actuators through the network. For example, in the EPS system, this microcomputer controlled power steering system has the characteristics of fewer components, small mass, and small volume. 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 ratio will decrease, and the steering force will gradually increase, making the car’s driving direction smoother and safer.
When driving at very low speeds, the steering ratio will increase. At this point, just slightly turning the steering wheel for a small angle will result in a significant change in body displacement, which will make many tasks easier, such as parking and positioning work; The characteristic of this system is to improve the vehicle’s steering ability and steering response characteristics, while also increasing the vehicle’s stability at high speeds and maneuverability at low speeds. In addition, as EPS can apply an additional torque to the steering wheel as needed, the driver can take steering measures based on this torque prompt signal, which is the steering suggestion function of this system. The system mainly consists of an electronic controller, a motor, and a motion transmission mechanism, including a motor speed sensor, a steering torque sensor, and a steering wheel angle sensor. Other systems, such as the EPS system, have played an irreplaceable and important role.
Application of 2 sensors in suspension system control
The work of the sensor 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 synthesizes the motion of the vehicle 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 the change of vehicle posture, thus realizing the control of handling stability, driving stability and vehicle comfort. The continuous damping control system ADC is composed of four control units, CAN, four wheel vertical acceleration sensors, four body vertical acceleration sensors and four damper proportional valves.
Application of sensor in electronic control system of driving and braking
1 Sensor application in traction control system TCS
Because the driving torque of the driving wheel is too large, the driving wheel will slip relative to the ground. According to the calculation, the safe slip rate of the drive wheel should not exceed 20%, so 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 the same ECU. The work 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 condition of the car, and then take corresponding measures.
Application of 2 sensors in ESP of vehicle dynamics
ESPThe system is an active safety system, which enables the vehicle to have more comfortable handling and better Directional stability. Its basic working principle is to analyze the input signal of the sensor, perform logical operations, and determine the expected vehicle motion state of the driver; By adjusting the longitudinal force of the wheels and the driver’s expectations of the vehicle, understand the actual motion state of the vehicle. Therefore, it requires more sensors than ABS and TCS to control the vehicle’s yaw motion. This type of sensor recognizes the driver’s expectations of the vehicle, including steering wheel sensors, lateral acceleration sensors, vehicle yaw rate sensors, and brake master cylinder hydraulic sensors.
Application of Three Sensors in ABS
Anti-lock braking system (ABS) is one of the most important safety components in automotive electronic devices, which has been developed for the longest time and has been widely applied. Its working principle is to control and prevent the wheel from locking when the car is braking, and ensure that the best sliding rate (5% – 20%) is achieved between the wheel and the ground. In this way, when the vehicle brakes on any road surface, the longitudinal peak coefficient of adhesion and large lateral coefficient of adhesion can be reached between the wheels and the ground, so as to ensure that the unsafe conditions such as wheel lockup, slip and loss of steering ability will not occur when the vehicle brakes, reduce the braking distance, and improve the handling stability and safety of the vehicle.
The sensor that plays a role is the anti-lock brake sensor. It mainly uses the wheel angular speed sensor to detect the wheel speed, control the brake oil pressure when the slip rate of each wheel is 20%, improve its braking performance, and achieve the purpose of ensuring vehicle handling and stability. Among them, wheel speed sensor is a very important device of ABS. Its main work is to provide the ECU with reliable and accurate wheel speed in a timely manner. If there is no 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 includes electromagnetic type, Hall type and magnetoresistive type.
Development trend of application of 4 sensors in automobile chassis electronic control
With the development of electronic technology and automobile industry, the development of automobile sensors will become one of the key factors affecting the development of high-grade, electronic and automatic automobile. The higher the degree of automation of automobiles, the greater the dependence on sensors. Therefore, many automotive electronics industries focus on the research and development of automotive sensor technology. Because the electronic control system of automobile chassis is composed of many systems, the types and quantities of sensors required by it are also diverse. Therefore, it is necessary and inevitable to develop new sensors with high accuracy, high reliability and low cost. In order to meet this need, the development trend of sensors in the future automotive chassis electronic control system will be towards integration, intelligence and miniaturization; On the basis of basic research, discover new phenomena, adopt new principles, develop new materials and adopt new technologies. Make the sensor more accurate and the technology content more and more high, so as to better promote the development of electronic technology and even the automobile industry.
Introduction to Development Trends
An intelligent sensor is a type of sensor with a microcomputer, which has various functions such as detection, judgment, and information processing. Compared with traditional sensors, it can correct measurement data by judging the working status of the sensor, thereby reducing the impact of environmental factors such as temperature. Its biggest advantage lies in its ability to comprehensively perceive the condition of drivers and passengers, transportation facilities, and surrounding environmental information; Be able to determine whether the driver and passengers are in optimal condition, whether the vehicle and personnel are in danger of life, and take corresponding measures in a timely manner. The difference is that it uses software to solve problems that are difficult for hardware in ordinary sensors. For example, completing data calculation and processing, this intelligent sensor not only has a large coverage range and output signal, but also has high accuracy, high signal-to-noise ratio, good anti-interference performance, and many also have self checking function. In the future, if this type of sensor can be applied to the automotive chassis electronic control system, 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 type of sensor can detect two or more characteristic or chemical parameters, thereby reducing the number of automotive chassis sensors and improving the accuracy of its electronic control system.
Micro sensors utilize microfabrication technology to encapsulate sensitive components, signal processors, data processors, and other components in a single chip. This type of sensor is easy to integrate, small in size, and inexpensive. 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 measuring mechanical, magnetic, and thermal quantities. Applying this sensor to the automotive chassis electronic control system will greatly optimize multiple performance of the vehicle.
Introduction to research methods and directions
The research and development of sensors is an inevitable trend in the development of electronic technology. The basic principle of various sensors is the same, which utilizes physical phenomena, chemical reactions, and biological effects. Therefore, the discovery of new phenomena and effects is an important foundation 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 high level, where we can freely control the composition of various materials. Given this, we can also design and manufacture various functional materials for sensors. For example, by adding different semiconductor oxides, various gas sensors with different performance can be manufactured; Optical fiber can be used as a sensor material, which is a significant discovery of sensor functional materials; In addition, many automotive electronics experts 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,
For sensors, the performance of their sensing components largely depends on the functional materials used. However, processing technology can also have a certain impact on the performance of components. Therefore, improving the processing technology will also be a direction for future research. With the application of various new materials such as semiconductors and ceramics in sensor sensitive components, many modern advanced processing technologies have gradually been introduced into the manufacturing process of automotive sensors, such as ion implantation technology, integration technology, micro processing technology, etc. By utilizing these new technologies, we can manufacture new sensitive components with high reliability, small size, light weight, and stable performance. For example, due to the rapid development of science and technology, the technology of Micro Electro Mechanical Systems (MEMS) is becoming increasingly mature, which has evolved from semiconductor integrated circuit technology. Microelectromechanical systems can be used to manufacture various micro sensors that can sensitively detect mechanical, magnetic, thermal, chemical, and biological quantities.
The widespread application of electronic technology in automotive technology has driven the rapid development of automotive chassis control systems towards electronic and intelligent directions, resulting in the birth of many automotive chassis electronic control systems. Sensors are the core components of electronic technology, and more and more sensors are being used in car chassis, greatly improving steering performance and vehicle driving safety.
At the same time, it also improves the economy and safety of cars. Various electronic steering control systems, such as AFS, EPS, and RWS, are more effective. They can provide 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, by combining this new information with the electronic control system of the automotive chassis, more new functions and systems will emerge, providing sufficient conditions and foundations for the development of the automotive industry.
