The automotive electronic stability system or dynamic yaw stability control system (ESP) is an anti-lock brake system ABS, a drive slip control system ASR, an electronic brake force distribution system EBD, a traction control system TCS, and an active body yaw control system AYC. The combination of basic functions such as ActiveYawControl is a new type of automotive active safety system. The system is an automotive chassis electronic control system jointly developed by Bosch GmbH (B0SCH) and Mercedes-Benz (MERCEDES-BENZ).
During the running of the car, due to external disturbances, such as sudden changes in pedestrians, vehicles, or the environment, the driver takes some emergency avoidance measures to make the car enter an unstable driving state, that is, a danger state that deviates from a predetermined driving route or flips the trend. Vehicles equipped with ESP can recognize and determine the unstable driving tendency of the car within a very short time of a few milliseconds. Through an intelligent electronic control program, the vehicle's drive transmission system and braking system can produce accurate responses. Properly eliminate these unsteady driving trends of cars, keep cars on the road and prevent rolling, and avoid traffic accidents.
The ESP system is a huge breakthrough in the active safety measures for automobiles. It controls the accidents to achieve safe driving and ensures the stability and safety of the vehicles in extremely harsh driving environments.
1. Composition of Automotive Electronic Stability System Based on ABS and ASR sensors, ESP adds yaw rate sensors, body rollover speed sensors, side acceleration sensors, hydraulic pressure sensors in the master cylinder, and the steering wheel Rotary angle sensors. The most important of these is the body rollover angular velocity sensor. This type of vehicle sensor is a similar product to the rotary angular velocity sensor used on the space shuttle and spacecraft. The body rollover speed sensor acts like a compass, monitoring the precise attitude of the car at the right time and monitoring every possible cornering speed of the car. Other sensors monitor the speed of the car and the speed difference of each wheel, and monitor the steering wheel rotation angle and the horizontal lateral acceleration of the car. When the brake occurs, the magnitude of the braking force and the distribution of the braking force of each wheel are monitored.
The ESP system includes 9 vehicle control functions, such as distance control, driver's drowsiness prevention, speed limit recognition, parallel warning, parking and night vision, ambient environment identification, integrated stability control and brake assist (BAS). Through the comprehensive application of 9 kinds of intelligent active safety technologies, ESP can reduce the risk of driver's loss of control of vehicles by about 80%.
The ESP intelligent on-board microcomputer control system monitors the driving status of the vehicle and the driver’s driving intention at any time through various sensors, and issues various instructions to the actuator in time to ensure that the vehicle is under conditions of braking, acceleration, and steering. Driving stability.
Figure 1 shows the installation of various sensors of the automotive electronic stability system ESP and the electronic stability system ECU on the car. Two ECUs with 56 kB of memory are equipped in the ECU. The ESP system uses these two microcomputers and various sensor signals to continuously monitor the working status of the electronic modules and systems in the vehicle and the driving posture of the car. For example, the speed sensor will self-check once every 20ms. The ESP system also makes full use of the advanced functions of anti-lock brake system ABS, brake assist system BAS and drive slip control system ASR through the signal exchange communication network between the electronic modules in the car. In case of emergency, such as when a stressed driver exerts insufficient braking force, the brake assist system BAS will automatically increase the braking force. When the ESP system fails to work properly, the ABS and ASR systems can still work to ensure that the car is running and braking normally.
The function of the ESP system is not simply the sum of the ABS and ASR functions, but the sum of the ABS and ASR functions, so that the car can maintain its driving stability under extremely severe conditions. The safety concept of the Mercedes-Benz A-Class sedans is the intelligent integration of advanced electronic control modules and hydraulic machinery actuators to achieve the greatest possible protection for vehicle and occupant safety.
2. The working principle of the automotive electronic stability system applies all external forces to the car, including braking force, driving force, and any kind of lateral force, which will cause the car to rotate around its center of mass. Based on this principle, the ESP system corrects the tendency of oversteering or understeering by interfering with the brake system and the drive transmission system when the car enters an unstable driving state, so that the car can maintain a stable driving state.
In the ROM of the microcomputer control system, standard technical data in the control program is stored in advance. When the vehicle sensors monitor and transmit various data of the vehicle driving state to the ECU at random, the ECU immediately calls out the pre-stored standard data to compare with it, and determines whether the sedan has an unstable driving tendency and degree of instability and causes. Once it is determined that the car has an unstable driving trend, the ESP system will automatically replace the driver to control the car, issue commands to the brake actuator and engine actuator through the microcomputer control system, and take the most favorable safety measures to correct the driving force and braking force. Prevent the occurrence of potentially dangerous conditions and restore the car to safe and stable driving conditions.
The safety measure implemented by the microcomputer control system instruction means that when the car sensor detects the tendency of the car to turn or deviate from the driving route demanded by the driver, the system can selectively brake the front or rear wheel of a single car, or If necessary, increase or decrease the output torque of the engine and adjust the driving force.
Figure 2 shows the trajectory of a car as it travels on a turning road. See Figure 2(a). When a car enters a corner, if the driver turns the steering radius of the car through the steering wheel larger than the radius of the curve, this condition is called understeer. If the car speed is too fast, the car may rush out of the road. The yaw rate sensor installed on the car will measure the steering deviation. The side acceleration sensor will measure the right acceleration and the steering wheel rotation angle sensor to measure the left understeer, and immediately monitor the dangerous trend of this out of the road. The signal is input to the ECU in the electronic stability system. The ECU immediately instructs the left rear wheel to apply a pulsed braking force, which generates an inward yaw moment at the center of mass of the car, forcing the car to deflect inwards about the center of mass by an angle. At the same time, the ECU immediately instructs the engine to reduce the output torque, lowers the speed of the car, and substitutes the driver to make the car steer angle slightly larger, so that the car can run at the steering angle required by the radius of the curve and return to the correct route.
On the contrary, see Figure 2(b), the initial position of the car's trajectory. If the driver turns the steering wheel too hard and makes the car turn radius smaller than the curve radius, this condition is called oversteering. If the car speed is too fast, the car may be turned outward due to centrifugal force. The yaw rate sensor, side acceleration sensor and steering wheel angle sensor mounted on the vehicle monitor the dangerous trend of this overturn and immediately input the signal to the ECU in the electronic stability system. The ECU promptly instructs the front right wheel to perform pulse braking. The brake force generates an outward yaw moment at the center of mass of the car, counteracting the centrifugal torsion moment, forcing the car to deflect outwardly about the center of mass, preventing the car from turning sideways. At the same time, the ECU control quickly reduces the driving force, lowers the speed of the car, and substitutes the driver to make the steering angle of the vehicle slightly smaller, so that the car can run at the steering angle required by the radius of the curve.
In summary, the ESP of the automotive electronic stability system adopts two different control methods when the car has an unstable driving tendency, so that the automobile can eliminate unstable driving factors and restore and maintain the predetermined driving state of the vehicle. The two control methods are, firstly, the ESP system controls the braking process of one or more wheels (pulse braking), and distributes the braking force applied to each wheel as needed to force the car to rotate around its center of mass. The rotational torque, while replacing the driver to adjust the direction of the car. Second, when necessary (such as the speed is too fast, the engine drive torque is too large), ESP system automatically adjusts the output torque of the engine to control the speed of the car.
By adopting the above two technical measures, it is possible to effectively prevent the car from turning over when the car performs a serpentine circuit test. The ESP system not only improves the stability of the car on a dry road, but also works when the road is poorly adhered, such as freezing, slippery, and gravel. Under the above-mentioned unfavorable conditions, the adhesion between the wheel and the road surface is reduced, and even the best driver can hardly maintain a high-speed car on the predetermined route, and the car is prone to sideways slipping and deviation, losing its stable direction. Sex, even a roll-over accident during a sharp turn, requires an ESP system.
3. Reliability of Automotive Electronic Stability Systems Since 1994, Mercedes-Benz has conducted comprehensive verification tests on the suitability and reliability of ESP systems.
In the ROM of the microcomputer control system, the standard technical data in the control program stored in advance should be derived from a large number of actual vehicle test data. However, due to the actual vehicle test without safety protection, it is possible to cause irreparable consequences of safety accidents. Therefore, simulators were used to obtain standard technical data. A large number of data collected through experiments are input in the simulator, which can simulate many complex road conditions and driving processes. 80 seat Mercedes simulators were used to simulate the road driving test with a speed of 100 km/h, and the responses of various vehicles with various performances were obtained. Simulator detection methods are both safe and can provide a lot of data that real vehicle tests cannot measure. For example, in the four corners of the test site, simulators were used to simulate the sudden icing of the road surface, which would reduce the adhesion between the wheel and the road by more than 70% over a few meters. If the car does not have an ESP system, 78% of drivers cannot stabilize their cars on icy roads, and they may also suffer damage caused by 3 consecutive turnovers of the car. With the ESP system, all drivers who have participated in the simulation test can avoid car rollover accidents.
In 1995, the Mercedes-Benz S-Class began to install ESP systems. The outstanding safety and security performance of the ESP system greatly reduced the possibility of turning the car under various road conditions and cornering. At the same time, the braking distance between the car on curved roads and on slippery roads is shortened, and the driving ability in the car line is enhanced in the corners. In 1998, the Mercedes-Benz A-Class minicar was also installed. The ESP system enables this type of A-class mini-car developed using a large number of high-tech technologies to overcome the shortcomings of personal injury and property loss caused by a lateral turnover when the car is steered with a small turning radius due to a narrow body. A car with excellent safety performance.
At present, Mercedes-Benz's S600, CL600, sL600, FA30, E320, 4MATIC, and high-performance E55AMG and C43AMG are all equipped with ESP systems. In 2002, all G-class cars were installed on the car.
4. Next-Generation Automotive Electronic Stability System Next-generation automotive electronic stability system integrates Active Steering Control (ASC) and Active Suspension Control (ADC) of the optional suspension mode with ESP to make the car's dynamic stability The control technology is more perfect and improves the driving stability and handling stability of the car in any situation.
In non-dangerous driving conditions, active steering control system makes driving more flexible to increase driving pleasure. Under dangerous driving conditions, the active steering control system and the braking system and engine management system jointly control the driving stability and ride comfort of the vehicle.
5. Integrated stability control system The integrated stability control system has comprehensive control of all active systems on the vehicle under any given conditions, such as the functions of driving, braking and operating systems. Compared with the current active vehicle stability control system, the integrated stability control system can continuously control the vehicle and achieve individual control.
6. Development of Electronic Control System for Chassis (1) Integrated Chassis Management System With the rapid development of electronic technologies, especially large-scale integrated circuits and micro-computer technologies, the degree of automotive electronics has become higher and higher. The chassis system of the car also changed the mechanical structure that used the hydraulic or pneumatic actuator to transmit force. It began to enter the electronic servo control (By-wire, the electrical signal is connected between the control device and the actuator instead of the mechanical device. At the connection stage, the chassis integrated control system has also begun to appear. The advanced chassis electronic control system optimizes the attachment between the wheels and the ground, significantly improving the power, safety and comfort of the car.
Car chassis electronic control system will gradually form an integrated chassis management (ICM) system. The system will integrate all the chassis electronic control subsystems to achieve the sharing of hardware, energy, and information among subsystems, so as to maximize the benefits of system integration and improve the safety, comfort, and economy of the vehicle. . Figure 3 shows the hierarchical structure of the ICM system. The upper layer of the structure diagram only contains some key monitoring functions. At this level, the system manages the engine, drive train, and chassis system through a "coordinator" ECU. Blank boxes represent other functions such as navigation and ACC functions. The lower level of the structure diagram represents the current electronic control system, but they are no longer a single working module, but are coordinated under the supervision and management of the upper unit. Sensors and actuators in the system can be divided into two categories: traditional and smart. There is only a direct physical connection between conventional sensors and actuators and their respective ECUs, and bus interfaces are used between smart sensors and actuators and ECUs to transmit data. In general, they all have self-diagnosis capabilities and certain sensor signal processing capabilities.
(2) Dynamic Body Control System (DynamicBodyControl)
For multipurpose sports cars (SUVs) and other high center-of-gravity vehicles, the power body control system maximizes steering stability and enhances driving comfort. In the off-road driving of the car, the axles cooperate with each other to obtain better traction performance. The power body control system uses 1 or 2 active balance bar modules to prevent the car from swaying when cornering by applying an adjustable preload to the balance bar. When the car body is inclined, the accelerometer monitors the tendency of the car to slide. The signal is transmitted to the control system ECU. The ECU commands the balance rod actuator to pass in pressure oil. The pressure oil generates a force that is measured according to the accelerometer. The magnitude of the lateral acceleration and the time when the car is shaken are determined.
During the running of the car, due to external disturbances, such as sudden changes in pedestrians, vehicles, or the environment, the driver takes some emergency avoidance measures to make the car enter an unstable driving state, that is, a danger state that deviates from a predetermined driving route or flips the trend. Vehicles equipped with ESP can recognize and determine the unstable driving tendency of the car within a very short time of a few milliseconds. Through an intelligent electronic control program, the vehicle's drive transmission system and braking system can produce accurate responses. Properly eliminate these unsteady driving trends of cars, keep cars on the road and prevent rolling, and avoid traffic accidents.
The ESP system is a huge breakthrough in the active safety measures for automobiles. It controls the accidents to achieve safe driving and ensures the stability and safety of the vehicles in extremely harsh driving environments.
1. Composition of Automotive Electronic Stability System Based on ABS and ASR sensors, ESP adds yaw rate sensors, body rollover speed sensors, side acceleration sensors, hydraulic pressure sensors in the master cylinder, and the steering wheel Rotary angle sensors. The most important of these is the body rollover angular velocity sensor. This type of vehicle sensor is a similar product to the rotary angular velocity sensor used on the space shuttle and spacecraft. The body rollover speed sensor acts like a compass, monitoring the precise attitude of the car at the right time and monitoring every possible cornering speed of the car. Other sensors monitor the speed of the car and the speed difference of each wheel, and monitor the steering wheel rotation angle and the horizontal lateral acceleration of the car. When the brake occurs, the magnitude of the braking force and the distribution of the braking force of each wheel are monitored.
The ESP system includes 9 vehicle control functions, such as distance control, driver's drowsiness prevention, speed limit recognition, parallel warning, parking and night vision, ambient environment identification, integrated stability control and brake assist (BAS). Through the comprehensive application of 9 kinds of intelligent active safety technologies, ESP can reduce the risk of driver's loss of control of vehicles by about 80%.
The ESP intelligent on-board microcomputer control system monitors the driving status of the vehicle and the driver’s driving intention at any time through various sensors, and issues various instructions to the actuator in time to ensure that the vehicle is under conditions of braking, acceleration, and steering. Driving stability.
Figure 1 shows the installation of various sensors of the automotive electronic stability system ESP and the electronic stability system ECU on the car. Two ECUs with 56 kB of memory are equipped in the ECU. The ESP system uses these two microcomputers and various sensor signals to continuously monitor the working status of the electronic modules and systems in the vehicle and the driving posture of the car. For example, the speed sensor will self-check once every 20ms. The ESP system also makes full use of the advanced functions of anti-lock brake system ABS, brake assist system BAS and drive slip control system ASR through the signal exchange communication network between the electronic modules in the car. In case of emergency, such as when a stressed driver exerts insufficient braking force, the brake assist system BAS will automatically increase the braking force. When the ESP system fails to work properly, the ABS and ASR systems can still work to ensure that the car is running and braking normally.
The function of the ESP system is not simply the sum of the ABS and ASR functions, but the sum of the ABS and ASR functions, so that the car can maintain its driving stability under extremely severe conditions. The safety concept of the Mercedes-Benz A-Class sedans is the intelligent integration of advanced electronic control modules and hydraulic machinery actuators to achieve the greatest possible protection for vehicle and occupant safety.
2. The working principle of the automotive electronic stability system applies all external forces to the car, including braking force, driving force, and any kind of lateral force, which will cause the car to rotate around its center of mass. Based on this principle, the ESP system corrects the tendency of oversteering or understeering by interfering with the brake system and the drive transmission system when the car enters an unstable driving state, so that the car can maintain a stable driving state.
In the ROM of the microcomputer control system, standard technical data in the control program is stored in advance. When the vehicle sensors monitor and transmit various data of the vehicle driving state to the ECU at random, the ECU immediately calls out the pre-stored standard data to compare with it, and determines whether the sedan has an unstable driving tendency and degree of instability and causes. Once it is determined that the car has an unstable driving trend, the ESP system will automatically replace the driver to control the car, issue commands to the brake actuator and engine actuator through the microcomputer control system, and take the most favorable safety measures to correct the driving force and braking force. Prevent the occurrence of potentially dangerous conditions and restore the car to safe and stable driving conditions.
The safety measure implemented by the microcomputer control system instruction means that when the car sensor detects the tendency of the car to turn or deviate from the driving route demanded by the driver, the system can selectively brake the front or rear wheel of a single car, or If necessary, increase or decrease the output torque of the engine and adjust the driving force.
Figure 2 shows the trajectory of a car as it travels on a turning road. See Figure 2(a). When a car enters a corner, if the driver turns the steering radius of the car through the steering wheel larger than the radius of the curve, this condition is called understeer. If the car speed is too fast, the car may rush out of the road. The yaw rate sensor installed on the car will measure the steering deviation. The side acceleration sensor will measure the right acceleration and the steering wheel rotation angle sensor to measure the left understeer, and immediately monitor the dangerous trend of this out of the road. The signal is input to the ECU in the electronic stability system. The ECU immediately instructs the left rear wheel to apply a pulsed braking force, which generates an inward yaw moment at the center of mass of the car, forcing the car to deflect inwards about the center of mass by an angle. At the same time, the ECU immediately instructs the engine to reduce the output torque, lowers the speed of the car, and substitutes the driver to make the car steer angle slightly larger, so that the car can run at the steering angle required by the radius of the curve and return to the correct route.
On the contrary, see Figure 2(b), the initial position of the car's trajectory. If the driver turns the steering wheel too hard and makes the car turn radius smaller than the curve radius, this condition is called oversteering. If the car speed is too fast, the car may be turned outward due to centrifugal force. The yaw rate sensor, side acceleration sensor and steering wheel angle sensor mounted on the vehicle monitor the dangerous trend of this overturn and immediately input the signal to the ECU in the electronic stability system. The ECU promptly instructs the front right wheel to perform pulse braking. The brake force generates an outward yaw moment at the center of mass of the car, counteracting the centrifugal torsion moment, forcing the car to deflect outwardly about the center of mass, preventing the car from turning sideways. At the same time, the ECU control quickly reduces the driving force, lowers the speed of the car, and substitutes the driver to make the steering angle of the vehicle slightly smaller, so that the car can run at the steering angle required by the radius of the curve.
In summary, the ESP of the automotive electronic stability system adopts two different control methods when the car has an unstable driving tendency, so that the automobile can eliminate unstable driving factors and restore and maintain the predetermined driving state of the vehicle. The two control methods are, firstly, the ESP system controls the braking process of one or more wheels (pulse braking), and distributes the braking force applied to each wheel as needed to force the car to rotate around its center of mass. The rotational torque, while replacing the driver to adjust the direction of the car. Second, when necessary (such as the speed is too fast, the engine drive torque is too large), ESP system automatically adjusts the output torque of the engine to control the speed of the car.
By adopting the above two technical measures, it is possible to effectively prevent the car from turning over when the car performs a serpentine circuit test. The ESP system not only improves the stability of the car on a dry road, but also works when the road is poorly adhered, such as freezing, slippery, and gravel. Under the above-mentioned unfavorable conditions, the adhesion between the wheel and the road surface is reduced, and even the best driver can hardly maintain a high-speed car on the predetermined route, and the car is prone to sideways slipping and deviation, losing its stable direction. Sex, even a roll-over accident during a sharp turn, requires an ESP system.
3. Reliability of Automotive Electronic Stability Systems Since 1994, Mercedes-Benz has conducted comprehensive verification tests on the suitability and reliability of ESP systems.
In the ROM of the microcomputer control system, the standard technical data in the control program stored in advance should be derived from a large number of actual vehicle test data. However, due to the actual vehicle test without safety protection, it is possible to cause irreparable consequences of safety accidents. Therefore, simulators were used to obtain standard technical data. A large number of data collected through experiments are input in the simulator, which can simulate many complex road conditions and driving processes. 80 seat Mercedes simulators were used to simulate the road driving test with a speed of 100 km/h, and the responses of various vehicles with various performances were obtained. Simulator detection methods are both safe and can provide a lot of data that real vehicle tests cannot measure. For example, in the four corners of the test site, simulators were used to simulate the sudden icing of the road surface, which would reduce the adhesion between the wheel and the road by more than 70% over a few meters. If the car does not have an ESP system, 78% of drivers cannot stabilize their cars on icy roads, and they may also suffer damage caused by 3 consecutive turnovers of the car. With the ESP system, all drivers who have participated in the simulation test can avoid car rollover accidents.
In 1995, the Mercedes-Benz S-Class began to install ESP systems. The outstanding safety and security performance of the ESP system greatly reduced the possibility of turning the car under various road conditions and cornering. At the same time, the braking distance between the car on curved roads and on slippery roads is shortened, and the driving ability in the car line is enhanced in the corners. In 1998, the Mercedes-Benz A-Class minicar was also installed. The ESP system enables this type of A-class mini-car developed using a large number of high-tech technologies to overcome the shortcomings of personal injury and property loss caused by a lateral turnover when the car is steered with a small turning radius due to a narrow body. A car with excellent safety performance.
At present, Mercedes-Benz's S600, CL600, sL600, FA30, E320, 4MATIC, and high-performance E55AMG and C43AMG are all equipped with ESP systems. In 2002, all G-class cars were installed on the car.
4. Next-Generation Automotive Electronic Stability System Next-generation automotive electronic stability system integrates Active Steering Control (ASC) and Active Suspension Control (ADC) of the optional suspension mode with ESP to make the car's dynamic stability The control technology is more perfect and improves the driving stability and handling stability of the car in any situation.
In non-dangerous driving conditions, active steering control system makes driving more flexible to increase driving pleasure. Under dangerous driving conditions, the active steering control system and the braking system and engine management system jointly control the driving stability and ride comfort of the vehicle.
5. Integrated stability control system The integrated stability control system has comprehensive control of all active systems on the vehicle under any given conditions, such as the functions of driving, braking and operating systems. Compared with the current active vehicle stability control system, the integrated stability control system can continuously control the vehicle and achieve individual control.
6. Development of Electronic Control System for Chassis (1) Integrated Chassis Management System With the rapid development of electronic technologies, especially large-scale integrated circuits and micro-computer technologies, the degree of automotive electronics has become higher and higher. The chassis system of the car also changed the mechanical structure that used the hydraulic or pneumatic actuator to transmit force. It began to enter the electronic servo control (By-wire, the electrical signal is connected between the control device and the actuator instead of the mechanical device. At the connection stage, the chassis integrated control system has also begun to appear. The advanced chassis electronic control system optimizes the attachment between the wheels and the ground, significantly improving the power, safety and comfort of the car.
Car chassis electronic control system will gradually form an integrated chassis management (ICM) system. The system will integrate all the chassis electronic control subsystems to achieve the sharing of hardware, energy, and information among subsystems, so as to maximize the benefits of system integration and improve the safety, comfort, and economy of the vehicle. . Figure 3 shows the hierarchical structure of the ICM system. The upper layer of the structure diagram only contains some key monitoring functions. At this level, the system manages the engine, drive train, and chassis system through a "coordinator" ECU. Blank boxes represent other functions such as navigation and ACC functions. The lower level of the structure diagram represents the current electronic control system, but they are no longer a single working module, but are coordinated under the supervision and management of the upper unit. Sensors and actuators in the system can be divided into two categories: traditional and smart. There is only a direct physical connection between conventional sensors and actuators and their respective ECUs, and bus interfaces are used between smart sensors and actuators and ECUs to transmit data. In general, they all have self-diagnosis capabilities and certain sensor signal processing capabilities.
(2) Dynamic Body Control System (DynamicBodyControl)
For multipurpose sports cars (SUVs) and other high center-of-gravity vehicles, the power body control system maximizes steering stability and enhances driving comfort. In the off-road driving of the car, the axles cooperate with each other to obtain better traction performance. The power body control system uses 1 or 2 active balance bar modules to prevent the car from swaying when cornering by applying an adjustable preload to the balance bar. When the car body is inclined, the accelerometer monitors the tendency of the car to slide. The signal is transmitted to the control system ECU. The ECU commands the balance rod actuator to pass in pressure oil. The pressure oil generates a force that is measured according to the accelerometer. The magnitude of the lateral acceleration and the time when the car is shaken are determined.
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