Adaptation of the steering feel in steer-by-wire steering systems

Abstract

A method for adapting the steering feel for a driver of a vehicle at an input element of the vehicle is described. The vehicle has a steer-by-wire steering system. The method comprises creating a reference of the steering feel. The method further comprises selecting scaling factors for the reference model such that characteristics of the steering feel remain constant for different steering ratios. The method further comprises adapting the steering feel using the scaling factors.

Claims

1. A method for adapting a steering feel for a driver of a vehicle at an input element of the vehicle, the vehicle including a steer-by-wire steering system, the method comprising: creating a reference model of the steering feel, the reference model including a plurality of torque components; selecting a plurality of scaling factors, each respective scaling factor in the plurality of scaling factors corresponding to a respective torque component of the plurality of torque components, each respective scaling factor in the plurality of scaling factors being determined based on a reference value and an instantaneous value for the associated respective torque component, such that characteristics of the steering feel remain constant for different steering ratios; and adapting the steering feel using the reference model of the steering feel and the scaling factors.

2. The method as claimed in claim 1, the creating the reference further comprising: creating the reference model with the plurality of components including a basic steering torque component having as input variables toothed bar force and vehicle speed.

3. The method as claimed in claim 1, the selecting the plurality of scaling factors further comprising: selecting each scaling factor of the plurality of scaling factors based on a ratio of a reference ratio and an instantaneous ratio.

4. The method as claimed in claim 1, the adapting the steering feel further comprising: determining a setpoint steering feel as equal to a sum of products, each product being a product of a respective scaling factor of the plurality of scaling factors with the associated respective torque component of the plurality of torque components.

5. The method as claimed in claim 1, the selecting the plurality of scaling factors further comprising: determining each scaling factor of the plurality of scaling factors as equal to a ratio of the reference value and the instantaneous value for the associated respective torque component.

6. The method as claimed in claim 1, wherein the input element is a steering wheel.

7. A controller for adapting a steering feel for a driver of a vehicle at an input element of the vehicle, the controller being part of a steering system of the vehicle, the controller comprising: a processor configured to: create a reference model of the steering feel, the reference model including a plurality of torque components; select a plurality of scaling factors, each respective scaling factor in the plurality of scaling factors corresponding to a respective torque component of the plurality of torque components, each respective scaling factor in the plurality of scaling factors being determined based on a reference value and an instantaneous value for the associated respective torque component, such that characteristics of the steering feel remain constant for different steering ratios; and adapt the steering feel using the reference model of the steering feel and the scaling factors.

8. A steering system for a vehicle, the steering system comprising: a controller configured to adapt a steering feel for a driver of the vehicle at an input element of the vehicle, the controller having a processor configured to: create a reference model of the steering feel, the reference model including a plurality of torque components; select a plurality of scaling factors, each respective scaling factor in the plurality of scaling factors corresponding to a respective torque component of the plurality of torque components, each respective scaling factor in the plurality of scaling factors being determined based on a reference value and an instantaneous value for the associated respective torque component, such that characteristics of the steering feel remain constant for different steering ratios; and adapt the steering feel using the reference model of the steering feel and the scaling factors.

9. The steering system as claimed in claim 8, wherein the steering system includes one of (i) a central controller and (ii) a single-wheel controller.

10. The method as claimed in claim 1, the creating the reference further comprising: creating the reference model with components including an active return component having as input variables steering wheel angle, driver torque, and vehicle speed.

11. The method as claimed in claim 1, the creating the reference further comprising: creating the reference model with components including a damping component having as input variables steering wheel angular velocity, driver torque, and vehicle speed.

12. The method as claimed in claim 1, the creating the reference further comprising: creating the reference model with components including a hysteresis component having as input variables steering wheel angular velocity, driver torque, and vehicle speed.

13. The method as claimed in claim 1, the creating the reference further comprising: creating the reference model with components including an inertia component having as input variables steering wheel angular acceleration, driver torque, and vehicle speed.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further details and advantages of the disclosure become clear on the basis of the exemplary embodiments represented in the drawings. In the drawings

(2) FIG. 1 shows a representation of the elements of a steering feel application device, and

(3) FIG. 2 shows a flow chart of a sequence of a steering feel application according to the disclosure.

DETAILED DESCRIPTION

(4) FIG. 1 shows a device for forming a steering feel for the driver of the relevant vehicle, wherein the device can be made up of different components. For example, including a first component 2, which provides a basic steering torque, a component 3, which applies an active return torque, whereby a desired setpoint return behavior of the steering wheel to the center results over the entire vehicle speed range. In addition, one component 4 can generate a damping, one further component 5 yields a hysteresis behavior, and one component 6 results in an inertia.

(5) Input variables of the component basic steering torque 2 can be a toothed rod force and the vehicle speed. Input variables of the active return 3 can be the steering wheel angle, the driving torque, and the vehicle speed. With respect to the input variable of the instantaneous steering wheel angle, an appropriate setpoint return speed is predefined. This property determines the vehicle response and the return of the vehicle axle to the center. Therefore, in the case of ratios that are more direct than the reference ratio, there is a smaller steering wheel angle given the same wheel position and the return to the center must take place correspondingly more slowly. In the case of indirect ratios, the behavior is the other way around, so that the setpoint return speed must be increased in order to achieve a similar behavior as in the reference application of the steering feel. Input variables of the damping 4 can be the steering wheel angular velocity, the driving torque, and the vehicle speed. Input variables in the calculation of the hysteresis 5 can be the steering wheel angular velocity, the driving torque, and the vehicle speed. Input variables of the component 6 can be the steering wheel acceleration, the driving torque, and the vehicle speed.

(6) A particular scaling factor can be calculated for the steering wheel angle variables for all elements, which results from the ratio of the reference ratio with respect to the instantaneous ratio.

(7) The corresponding formula for the scaling factor results as: Scaling factor steering feel application=(starting ratio reference application)/(instantaneous ratio).

(8) The scaling factor necessary for all modules therefore results as a ratio of the reference ratio with respect to the instantaneous ratio. The instantaneous ratio depends on the different circumstances, such as toothed bar stroke and/or speed of the relevant vehicle. The scaling factor as the result of the ratio formation affects the angle, the angular velocity, and/or the angular acceleration of the steering wheel. The scaling factor can be additionally adapted, for example, to the driving situation or to the driving style of the driver.

(9) FIG. 2 shows a flow chart for the application of a steering feel onto a steering wheel, wherein, in a first step, a reference model is created 7 as a setpoint value of a desired steering feel. This reference model can comprise five units and, in fact, a basic steering torque, an active return, a damping, a hysteresis, and an inertia 8. If it results that the present steering feel, which a driver of the relevant vehicle perceives at the steering wheel, deviates 9 from this desired steering feel, an appropriate adaptation 10 of the steering behavior takes place, in particular of the basic steering torque, the active return, the damping, the hysteresis and/or the inertia, in order to maintain the characteristics of the steering feel.

(10) It is to be noted that the term “includes” does not rule out further elements or method steps, just as the term “a” and “one” does not rule out multiple elements and steps.

(11) The utilized reference numerals are intended merely to enhance the clarity and are not to be considered, in any way, as limiting, wherein the scope of protection of the disclosure is presented by the claims.