Function of ESP
Under certain road conditions and vehicle load conditions, the maximum adhesion provided by wheels is a constant value, that is, in the limit case, the longitudinal force (along the wheel rolling direction) and the lateral force (perpendicular to the wheel rolling direction) are a trade-off relationship. The electronic stability program can control the longitudinal braking force of each wheel independently, thus exerting influence on the lateral force, thus improving the handling performance of the vehicle.
When the longitudinal force reaches the extreme value (for example, the wheel is locked), the lateral force is zero. At this time, the lateral movement of the vehicle will be out of control, that is, it will slip, and it may be impossible to change lanes or turn according to the driver's wishes. The electronic stability program can detect and prevent the vehicle from slipping. When the electronic stability program detects that the vehicle is about to get out of control, it will apply braking force to specific wheels to help the vehicle drive in the direction expected by the driver.
When turning, the feasible control strategy is as follows: when the vehicle tends to understeer, the system can apply braking force to the rear wheel inside the turn. As the longitudinal force of this wheel increases, the lateral force it can provide decreases, and then a torque will be generated to help the car turn; When there is a tendency to oversteer, the system can apply braking force to the front wheels outside the turn. As the longitudinal force of this wheel increases, the lateral force it can provide decreases, and then a torque against steering is generated on the car body. So as to ensure the driving stability. Some electronic stability program systems will also reduce the engine power when the vehicle is out of control.
Extended data:
Components of ESP
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.
1. sensors: including 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: The actuator of ESP is a four-wheel braking system. Unlike vehicles without ESP, the braking system of vehicles with ESP has the function of pressure accumulation.
4. Communication device: ESP light on the dashboard.
References:
Baidu Encyclopedia-Body Stabilization System