Structural characteristics and diagnosis of Bosch ESP

ESP body electronic stability system ESP and bosch company

Electronic Stability Program (ESP) is a patent of Bosch Company [1]. 10 years ago, Bosch was the first company to put electronic stability program (ESP) into mass production. Because ESP is a patented product of Bosch, only Bosch's body electronic stability system can be called ESP. After Bosch, many companies have developed similar systems, such as vehicle dynamic control system (VDC) developed by Nissan [2] and vehicle stability control system (VSC) developed by Toyota [3]. Vehicle stability auxiliary control system (VSA) developed by Honda [4], dynamic stability control system (DSC) developed by BMW [5] and so on.

ESP overview

ESP system is actually a traction control system. Compared with other traction control systems, ESP can control not only the driving wheel but also the driven wheel. For example, rear-wheel drive cars often turn too much. At this time, the rear wheel is out of control and the ESP will slow down the outer front wheel to stabilize the car. When the steering is too little, ESP will slow down the inner rear wheel to correct the tracking direction, thus correcting the driving direction.

ESP system includes ABS (Anti-lock Brake System) and ASR (Anti-Side Slip System), which are the functional extensions of these two systems. Therefore, ESP can be regarded as the most advanced form of automobile anti-skid device at present. ESP system consists of control unit, steering sensor (monitoring the steering angle of the steering wheel), wheel sensor (monitoring the rotating speed of each wheel), sideslip sensor (monitoring the rotation state of the car body around the vertical axis), lateral acceleration sensor (monitoring the centrifugal force when the car turns) and so on. The control unit judges the driving state of the vehicle through the signals of these sensors, and then sends out control instructions. The difference between a car with ESP and a car with ABS and ASR is that ABS and ASR can only react passively, while ESP can detect and analyze the condition of the car and correct the driving mistakes before they occur. ESP is particularly sensitive to oversteer or understeer. For example, when a car turns left and oversteers (turns too fast), it will flick its tail to the right. When the sensor senses the slip, it will quickly brake the right front wheel to restore its adhesion and generate the opposite torque to keep the car in the original lane. Of course, there is a limit to everything. If the driver drives too fast blindly, it will be difficult to keep any existing safety devices.

Components of ESP

Sensors: steering sensor, wheel sensor, sideslip sensor, lateral acceleration sensor, steering wheel accelerator brake pedal sensor, etc. These sensors are responsible for collecting data on the state of the car body.

2.ESP computer: calculate the data collected by the sensor, calculate the physical state, and compare it with the preset data in the memory. When the data calculated by the computer exceeds the pre-stored value in the memory, that is, when the car body approaches or is out of control, the actuator is ordered to work to ensure that the driving state of the car body conforms to the driver's intention as much as possible.

3. Actuator: To put it bluntly, the actuator of ESP is the braking system of four wheels. In fact, ESP is to help drivers step on the brakes. Unlike a car without ESP, the brake system of a car with ESP has the function of accumulating pressure. Simply put, pressure storage means that when the driver doesn't step on the brakes as needed, the computer can pressurize the brake pipe of a wheel for the driver to make the wheel generate braking force. In addition, ESP can also control the power output of the engine. Anyway, he can get involved in related equipment!

4. Communication with the driver: ESP light on the dashboard.

Key technology of electrostatic precipitator

At present, the typical structure of automobile control system includes traditional brake system vacuum booster, pipeline and brake, sensor, wheel speed sensor, steering wheel angle sensor, lateral acceleration sensor, yaw rate sensor, brake master cylinder pressure sensor, hydraulic regulator, automobile stability control electronic control unit and auxiliary system engine management system.

Therefore, the development of the system depends on the breakthrough of the following key technologies.

① Improvement of sensing technology ". Sensors used in the system include automobile yaw rate sensor, lateral acceleration sensor, steering wheel angle sensor, brake pressure sensor and throttle opening sensor. They are all indispensable and important parts of the system. Improving its reliability and reducing its cost has always been the goal pursued by developers in this field.

(2) The structure design of hydraulic braking system is small in size, light in weight and low in cost.

③ Software and hardware design. Because it is necessary to estimate the state variables of vehicle operation and calculate the corresponding motion control quantity, the calculation processing capacity and program capacity are several times larger than the system. Generally, a variety of structures are adopted. The research of software is the most important, and the modern control theory based on model has been difficult to adapt to the control of such a complex system, so it is necessary to find a nonlinear control algorithm with strong robustness.

④ Improve the control function. Through the interconnection with the engine and transmission system, its control function can be better played. For example, the automatic transmission transmits the current mechanical transmission ratio, the torque ratio of the torque converter and the gear position to estimate the driving force on the driving wheel. When it is recognized that it is on the road with low adhesion coefficient, the driver will be prohibited from engaging in low gear. When starting on this road, the transmission system will inform you in advance to shift into second gear, which will significantly improve the starting comfort of high-powered vehicles.

Working process of electric submersible pump

1, this car turns left when the vehicle turns understeer (that is, turns too fast). The ESP sensor will tell the computer the news of understeer, and then the computer will control the brake of the left rear wheel to generate tension and torsion to counter the understeer trend of the front wheel pushing to the right.

2, or turn left, when the rear wheel grip is insufficient or the accelerator driven by the rear wheel is pressed hard, there will be excessive steering (that is, ass dumping). ESP will control the right front wheel brake and reduce the power output of the engine. Correct the wrong steering posture.

3. When the linear brake deviates due to uneven ground adhesion (cars with ABS will also appear. When it snows, I always play in the snow, and my car will go sideways. ESP will control the wheels with strong adhesion to reduce the braking force and let the car follow the driver's expected driving route. Similarly, when turning while braking, ESP will also control some wheels to increase or decrease the braking force, so that the car can run according to the driver's intention.

The most important feature of ESP

This is its initiative. If ABS reacts passively, then ESP can nip in the bud.