EP-4549268-B1 - METHOD FOR CONTROLLING THE WHEEL SLIP OF A MOTOR VEHICLE, CONTROL DEVICE AND MOTOR VEHICLE

Inventors

• LAPIS, Leonard

Dates

Publication Date

20260513

Application Date

20241025

Claims (7)

1. Method for controlling the wheel slip of a motor vehicle having at least two wheels (10), an electromechanical braking system (11), an electric drive system (12) and a steer-by-wire steering system (13), wherein the method comprises the following steps: - converting a target trajectory (14) of the motor vehicle into a target movement of the motor vehicle; - determining wheel-specific target longitudinal and target transverse slip values (15) for the wheels (10) based on the target movement using a vehicle and tyre model (16), wherein the vehicle and tyre model (16) maps the ratio of longitudinal and transverse slip values of the wheels (10) to the maximum transmissible longitudinal and transverse forces of the wheels (10); and - adjusting actual longitudinal and actual transverse slip values of the wheels (10) to the respective target longitudinal and target transverse slip values (15) by the electromechanical brake system (11) and the electric drive system (12) as a function of a steering angle of the steer-by-wire steering system (13).
2. Method according to Claim 1, characterized in that the target longitudinal and target transverse slip values (15) are determined on the basis of the actual longitudinal and actual transverse slip values.
3. Method according to Claim 1 or Claim 2, characterized in that the ratio is mapped as a function of, in particular predicted, static and/or dynamic wheel loads of the wheels (10).
4. Method according to one of the preceding claims, characterized in that the ratio is mapped as a function of a coefficient of friction, in particular an estimated coefficient of friction, between the wheels (10) and the roadway.
5. Method according to one of the preceding claims, characterized in that the target trajectory (14) is provided by a human-machine interface and/or a computer-implemented method.
6. Control device for controlling the wheel slip of a motor vehicle having at least two wheels (10), an electromechanical braking system (11), an electric drive system (12) and a steer-by-wire steering system (13), wherein the control device is adapted to perform the following steps: - converting a target trajectory (14) of the motor vehicle into a target movement of the motor vehicle; - determining wheel-specific target longitudinal and target transverse slip values (15) for the wheels (10) based on the target movement using a vehicle and tyre model (16), wherein the vehicle and tyre model (16) maps the ratio of longitudinal and transverse slip values of the wheels (10) to the maximum transmissible longitudinal and transverse forces of the wheels (10); and - adjusting actual longitudinal and actual transverse slip values of the wheels (10) to the respective target longitudinal and target transverse slip values (15) by the electromechanical brake system (11) and the electric drive system (12) as a function of a steering angle of the steer-by-wire steering system (13).
7. Motor vehicle with a control unit (19) according to Claim 6.

Description

The invention relates to a method for controlling the wheel slip of a motor vehicle, a control unit and a motor vehicle. The document US2023/311849 This document describes a method for controlling actuators that act on the wheels of a motor vehicle to improve motion control for autonomous and manual driving. US2023/311849 aims to enable coordinated actuator operation and optimize vehicle operation, taking into account limitations such as friction-related restrictions on wheel forces and limitations of the actuators. To propel a motor vehicle, longitudinal and lateral forces are transmitted between the wheels or tires and the road surface. The vehicle's stability is ensured as long as the maximum transmissible longitudinal and lateral forces, i.e., the available force potential or the limit of adhesion, of the wheels are not exceeded. The maximum transmissible longitudinal and lateral forces of a wheel depend primarily on wheel slip, wheel load, and the coefficient of friction between the wheel and the road surface. Since wheel load and coefficient of friction are only partially controllable, wheel slip is the key parameter for actively ensuring the driving stability of a motor vehicle. Wheel slip is typically controlled by wheel actuators that brake and/or accelerate the wheels to adjust the actual longitudinal and lateral slip values to target values. It is known to determine these target longitudinal and lateral slip values based on a target trajectory provided by a human-machine interface, such as a control system with a steering wheel, pedals, and/or gearshift lever, or by software for automated and/or autonomous driving. Controlling wheel slip involves overcoming inertia and is subject to modeling and estimation errors. To ensure vehicle stability in every situation, control is therefore usually achieved with a safety margin above the adhesion limit, meaning that the available force potential of the wheels is only utilized up to a certain point. However, this can lead to deviations from the intended trajectory, especially in extreme situations, and thus compromise driving safety. The invention is therefore based on the objective of providing a method that enables the control of wheel slip in a motor vehicle with a reduced safety margin to the traction limit of the wheels. The invention is further based on the objective of providing a corresponding control unit and a motor vehicle. According to the invention, the problem is solved with regard to the method by the subject matter of claim 1, with regard to the control unit by the subject matter of claim 6 and with regard to the motor vehicle by the subject matter of claim 7. Specifically, the problem is solved by a method for controlling the wheel slip of a motor vehicle that has at least two wheels, an electromechanical braking system, an electric drive system and a steer-by-wire steering system. The process includes the following steps: Translating a target trajectory of the motor vehicle into a target movement of the motor vehicle; Determining wheel-specific target longitudinal and lateral slip values for the wheels based on the target movement using a vehicle and tire model; and Adjustment of the actual longitudinal and lateral slip values of the wheels to the respective target longitudinal and target lateral slip values by the electromechanical braking system and the electric drive system depending on a steering angle of the steer-by-wire steering system. The method according to the invention is based, firstly, on the idea of translating the target trajectory into a target movement of the motor vehicle in an intermediate step. This allows the target longitudinal and target lateral slip values to be determined using a vehicle and tire model in such a way that they represent the target movement with particular precision. In this way, modeling and estimation errors in determining the target longitudinal and target lateral slip values are reduced, so that only a small safety margin to the traction limit of the wheels needs to be maintained. Furthermore, it is advantageously provided that an electromechanical braking system and an electric drive system are used to adjust the actual longitudinal and lateral slip values to the target longitudinal and lateral slip values. Due to their reduced inertia, these systems enable a particularly rapid adjustment of the actual longitudinal and lateral slip values to the target longitudinal and lateral slip values, thus advantageously further reducing the required safety margin to the adhesion limit. The advantages mentioned in connection with the method also apply accordingly to the control unit according to the invention. The process steps described in connection with the method also apply in connection with the The control unit discloses, in such a way that the control unit is configured or adapted to carry out these procedural steps. A trajectory refers specifically to the temporal development of a motor vehicle's