2012/12/22
2
8.5 The ABS functions expand 8.5.1 The ASR system 8.5.2 The ESP system
2012/12/22
3
8.5.2 The ESP system 1. The basic function of the ESP; 2. Vehicle handling characteristic introduction. 3. ESP control systems
2012/12/22 15
The higher-level controllers input the nominal values to the lower-level controllers in the form of a nominal slip. The "observer" determines the controlled state variable (vehicle slip angle β).
2012/12/22
7
⑸ Depending upon the situation, even better utilization of the adhesion potential between the tires and the road when ABS and TCS intervene, and therefore improved traction and stopping distances in addition to improved steerability and stability.
2012/12/22
6
⑶ Enhances directional stability even during extreme steering maneuvers (panic reactions), resulting in a drastic reduction in the danger of skidding;
⑷ Improved handling behavior also in limit situations. For the driver, this behavior becomes predictable as a function of his (or her) experience. The vehicle remain fully under control even in critical traffic situations;
2012/12/22
5
Further to the advantages inherent in ABS and ASR, ESP improves the active driving safety in the following points:
⑴ Provides the driver with active support, even in laterally critical dynamic; ⑵ Enhances vehicle stability and tracking performance even in limit situations in all operating modes such as full braking, partial braking, coasting, accelerating, engine drag, and load shift;
2012/12/22
14
The overall system (see Fig.), shows the vehicle as the controlled system, with Sensors (1...5) for defining the controller input variables, and actuators (6 and 7) for influencing the tractive force and the braking force. Also shown are the hierarchically structured controller comprising the higherlevel vehicle dynamics controller, and the lower-level slip controllers.
2012/12/22
10
Lateral dynamics of a vehicle 1. Step input at steering wheel, steering- wheel angle fixed; 2. Track on highμroad; 3. Track on lowμroad with "open-loop" steering correction and yaw-rate control; 4. Track on low- μ road when the slip angle is also controlled (ESP);
2012/12/22
11
3. ESP control systems ⑴ control The control of the vehicle's behavior at the physical driving limit must influence the vehicle's three degrees of freedom in the plane of the road (longitudinal and lateral velocities, and yaw moment about the vertical axis) so that vehicle handling is in line with the driver's input and with the prevailing road conditions.
18
2012/12/22
In order to determine the desired performance, the signals are evaluated which define the driver's input.
These comprise the signals from the steering-wheel sensor (3, driver's steering input), the brake-pressure sensor (2, desired deceleration input), and the engine management (7, desired drive torque).
brief
2012/12/22
4
1. The basic function of the ESP While ABS prevents wheel lockup when braking and ASR (TCS) prevents spin of the driven wheels, ESP prevents the vehicle from "pushing out" of the turn or spinning out of the turn when it is steered.
2012/12/ed value of vehicle-motion variables ESPcontroller Sideslip- angle control and yaw- rate control
Slip controller with intorface to ESP
2012/12/22
19
Apart from the vehicle speed, the calculation of the desired performance also takes the coefficients of adhesion between the tires and the road into account. These are calculated from the signals outputted by the wheel-speed sensors (1), the lateral-acceleration sensor (5), the yaw-rate sensor (4), and the brake-pressure sensor (2).
2012/12/22
9
Lateral dynamics of a vehicle 1. Step input at steering wheel, steering- wheel angle fixed; 2. Track on highμroad; 3. Track on lowμroad with "openloop" steering correction and yawrate control; 4. Track on low- μ road when the slip angle is also controlled (ESP);
The automoive electronics control technique
Southeast University Mechanical Department
Feng Chong-Yi
2012/12/22
1
Previous lessen content review lessen (12/03/2012): The 8th chapter: The brake system 8.1 brief introduction of the Brake system 8.2 Anti-lock Brake System (ABS) 8.3 Criteria of control quality 8.4 ABS Versions 8.5 The ABS functions expand The contents for today (12/06/2012)