The ESP system is based on the sensitive elements (sensors) and actuators of a conventional anti-lock braking system (ABS), as well as on elements of the engine management system.
The main functions of the general stability control system are as follows.
- The Electronic Stability Program (ESP) function has the highest priority in terms of impact on the vehicle compared to other functions of the overall system.
The ESP system ensures stabilization of the vehicle on the trajectory of movement when cornering and stabilization of the straight-line movement of the vehicle in the presence of deviations from the course.
- Function of conventional anti-lock braking system ABS (Antilock brake system), which is designed to prevent the wheels from locking during vehicle braking. In this case, when braking, the speed sensors of all wheels measure and compare the intensity of the deceleration of wheel rotation. The system reduces the braking force in the branch of the hydraulic brake system that corresponds to the wheel experiencing the most intense deceleration.
- Anti-slip regulation function ASR (Acceleration slip regulation) controls the drive wheels. If one of the drive wheels rotates rapidly during acceleration, the system brakes this wheel by applying precisely calculated pressure to the brake cylinder.
- ETS traction control function (Electronic traction system).
- Forced idle speed control function (engine braking) on slippery road MSR (Engine braking regulation). Regulation is carried out by means of the engine management system (CDI) by reducing the braking torque transmitted from the engine to the drive wheels. This subsystem prevents the drive wheels from slipping when the accelerator pedal is released.
- Electronic Brakeforce Distribution EBV function (Electronic brake force distribution). By performing this function, the system distributes the braking force between the front and rear wheels. The system operates in a similar way to ABS. In EBV mode, the system reacts to changes in wheel speed earlier than in ABS mode. The need for such a function is dictated by the different deceleration rates of the front and rear wheels when the vehicle is underloaded.
- Function to increase the braking force during emergency braking BAS (Brake Assist system). When the brake pedal is pressed hard (sharply), which the system evaluates as the driver's desire to brake as quickly as possible, BAS increases the pressure in the brake cylinders (while simultaneously controlling the braking process with the ABS system).
9.046 Block diagram of the ESP system
Example A
The car understeers when turning left.
In this case, the front wheels are carried beyond the required trajectory to the outside of the turn.
Text republished from the website www.mercedesman.ru
Trajectory correction is achieved by precisely calculated braking of the rear left wheel.
Example B
The car oversteers on a left turn.
The rear wheels are pulled to the outside of the turn.
Trajectory correction is achieved by precisely calculated braking of the front right wheel.
VN 9.047 Scheme of correction of the trajectory of the car when passing a turn; a. Desired direction of movement; b. The wheel to which the corrective braking force is applied; c. Torque applied to the vehicle as a result of corrective braking; d. Front wheel slippage due to centrifugal force; e. Skidding of the rear wheels under the action of centrifugal force