Method for operating a steering system

Abstract

Method for operating a steering system (102) in a vehicle (100), in which data on a road condition of at least one road section ahead are evaluated and a steering characteristic of the steering system (102) is adapted as a function of this evaluation.

Description

[0001] The invention relates to a method for operating a steering system, in particular a steer-by-wire steering system, and an arrangement for carrying out the method. State of the art

[0002] In vehicles, steering is a device that serves to influence the direction of travel of the vehicle.

[0003] A steer-by-wire steering system transmits a steering command from a sensor via one or more control units exclusively electrically to an electromechanical actuator, which executes the steering command. Such a steering system typically includes a feedback actuator, e.g., a steering actuator, e.g., a rack and pinion actuator, and a unit for evaluating and calculating signals, which is implemented, for example, in software or software functions.

[0004] It is also known to select a steering characteristic depending on environmental influences and / or driving situations with the aid of information provided by an external information system, e.g. a cloud.

[0005] The publication DE 10 2020 212 447 A1 describes a method for adapting at least one steering characteristic of a steering system during its operation. In the method, adaptation information is retrieved or received from an external computing system using a communication module in at least one operating state. Using this adaptation information, the steering characteristic is dynamically adapted. The steering characteristic is, in particular, a steering behavior of the steering system and / or a steering feel of the steering system perceivable at a steering handle.

[0006] It is also known to convey to a driver a loss of road contact through a light steering feeling. Disclosure of the invention

[0007] Against this background, a method having the features of claim 1 and an arrangement according to claim 8 are presented. Embodiments emerge from the dependent claims and from the description.

[0008] A method for operating a steering system is presented in which data on a road condition of at least one road section ahead are evaluated and, depending on this evaluation, a steering characteristic of the steering system is adapted.

[0009] For example, at least one steering profile can be specified that represents the determined steering characteristics. This at least one steering profile is transferred to the steering system. The steering characteristics are then adjusted according to the at least one steering profile.

[0010] A fundamental distinction is made between steering characteristics, steering profile, and steering behavior. The steering profile comprises parameters, e.g., in the form of characteristic curves, which are used to operate the feedback actuator and the steering actuator. The application of the steering profile affects the steering characteristics. The steering profile can, for example, be present as software in the form of characteristic curves or parameters. The steering characteristics result from the interaction of software and mechanics when a specific steering profile is applied. The steering behavior is the behavior that is conveyed to the driver. This depends on the selected steering characteristic. The steering behavior is conveyed to the driver as steering feel.

[0011] The steering profile can also be selected based on exceedances and / or under-exceedances of the road surface friction coefficient.

[0012] In this embodiment, data on the road conditions in the area of ​​the vehicle are transmitted to the vehicle. This data is evaluated to determine whether the road conditions of a section of road ahead are such that an adjustment of the steering characteristics appears necessary. This adjustment is then carried out preventively, i.e., before the vehicle enters the relevant section of road.

[0013] The method can consider data from a navigation system, an electronic map, and also from the vehicle's navigation system to determine which road sections the vehicle will drive on in the future. As soon as a potentially dangerous future driving situation is detected due to the road conditions, the steering characteristics are adjusted. This occurs preventively, i.e., before driving on the relevant road section, and in sufficient time for the driver to be aware of the situation and adjust their driving style if necessary. If no critical road conditions are detected, the steering characteristics are maintained.

[0014] The steering characteristics can be adjusted individually for each driver or vehicle.

[0015] The steer-by-wire steering system used in the method typically comprises a feedback actuator associated with a steering handle and a steering actuator, e.g., a rack and pinion actuator. In one embodiment, the steering handle is designed as a steering wheel. However, other steering handles are also conceivable.

[0016] In one embodiment, at least one steering profile is adapted to the steering system. The steering profile typically represents the steering characteristics and is available, for example, in the form of a characteristic curve or a mathematical description of the course of a characteristic curve. This at least one steering profile can be created based on the specified steering characteristics. However, a steering profile can also be selected from a number of steering profiles. This selected steering profile is then best suited to implementing the specified steering characteristics.

[0017] In this embodiment, the steering characteristic refers to the steering behavior of the steering system. This steering behavior can be determined or described, for example, by a steering ratio. Alternatively or additionally, the steering characteristic can be a steering feel perceptible at a steering handle, in particular a steering feel perceptible by a driver. This steering feel is typically perceptible or tangible to the driver via the haptic feedback at the steering handle and can be conveyed by the feedback actuator.

[0018] A steering profile or characteristic curve can then be provided for the steering behavior and a steering profile or characteristic curve for the perceived steering feel. Dependencies may exist between these two steering profiles.

[0019] This design provides the driver with a steering feel that reflects the risk, or the impending or imminent risk, of a slippery road surface. This occurs, in particular, in a temporally or spatially advanced or extended manner, so that the driver can be proactively sensitized to critical road conditions. In this embodiment, the steering feel is thus applied not only directly in the area of ​​slippery conditions, but also for a wider area.

[0020] For the specific adjustment of the steering feel, it can be intended to provide at least a smoother steering in a conventional electromechanical power steering system, for example by introducing a higher steering assistance.

[0021] With a steer-by-wire steering system, the perceived smoothness can be achieved by reducing the counter-torque on the feedback actuator.

[0022] In order to avoid accidental oversteering resulting from the low steering torque, the steering ratio can be reduced at the same time in a steering system, e.g. a steer-by-wire steering system.

[0023] It is important that the automatic adaptation to environmental influences is specifically related to a smooth road surface and that this can automatically and temporarily provide a smoother steering profile with a possibly modified gear ratio.

[0024] In one embodiment, it is proposed that the steering profile be automatically and preventively adjusted when a road surface with a low coefficient of static friction is detected. The road surface is detected directly in the respective vehicle, e.g., with the aid of the steering system, ESP, or other sensors. A friction coefficient map, such as one provided by a cloud, is suitable for preventative detection.

[0025] In this configuration, steering assistance is increased in response to the detected road surface, thus enhancing the perceived ease of steering, which may already be present to some extent due to the slippery road surface. This provides the driver with a clearer haptic signal that contact with the road surface is being lost or is about to be lost.

[0026] With steer-by-wire steering, the steering ratio can also be made more indirect, reducing unwanted, excessive steering. This prevents the vehicle from suddenly reacting too strongly when the vehicle regains contact with the road.

[0027] The smoothness effect can be temporally or locally configured, for example, depending on the route and / or wheel rotation, so that it applies either precisely in the measured slippery area, as long as this can be precisely localized, or also in a defined area beyond it. This ensures that the driver is aware of the slippery road surface even when contact with the slippery area is very brief and therefore not noticeable under normal circumstances. This sensitizes the driver to the poor road conditions. In particular, a more indirect transmission ratio seems sensible in this case to avoid unintentionally sharp steering when there is grip and to ensure the familiar steering feel.

[0028] Additional steering profile characteristics, such as active return or damping, can also be included in the "black ice profile" display. However, these should be individually configured for each vehicle through tuning.

[0029] With the proposed system, drivers are informed early and intuitively via the steering system that the road surface is slippery or potentially slippery in some areas. This is possible even if there are only isolated slippery patches that might not be noticed by the driver without this function. The driver is encouraged to drive cautiously, which contributes to road safety.

[0030] The presented procedure is basically applicable to all steering systems, especially to steer-by-wire steering systems.

[0031] The presented arrangement is configured to carry out the described method and, for this purpose, has an evaluation unit for evaluating data on road conditions and for controlling the steering by influencing the steering characteristics or for specifying at least one steering profile. The arrangement can be implemented in hardware and / or software. Furthermore, the arrangement can be integrated into a control unit of a vehicle, in particular a motor vehicle, or be designed as such a control unit.

[0032] A steering system or a steering mechanism with such an arrangement is also presented. This steering mechanism is, for example, designed as a steer-by-wire steering mechanism and typically includes a feedback actuator, a steering actuator. The steering mechanism is typically associated with a steering handle, which can also be considered a component of the steering mechanism.

[0033] Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings.

[0034] It is understood that the features mentioned above and those to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own, without departing from the scope of the present invention. Short description of the drawings Fig. 1 shows a flow chart of a possible sequence of the presented procedure. Fig. 2 shows a schematic, highly simplified representation of a vehicle with an embodiment of the described arrangement for carrying out the presented method. Embodiments of the invention

[0035] The invention is illustrated schematically in the drawings using embodiments and is described in detail below with reference to the drawings.

[0036] Fig. 1 shows a flowchart of a possible embodiment of the presented method. In a first step 50, the vehicle begins its journey. In a next step 52, information on road conditions in the area of ​​the vehicle is retrieved, whereby the vehicle's planned route can also be specifically taken into account. If it is detected in a step 54 that a road condition is imminent on the planned route that could impair driving safety, e.g., due to a slippery road surface, the steering feel perceived by the driver is preventively adjusted in a step 56 so that the driver is warned in good time and can adapt their driving style, e.g., by reducing their speed.

[0037] Fig. Figure 2 shows a schematic representation of a vehicle, designated overall by reference numeral 100. This vehicle has a steer-by-wire steering system 102 with a feedback actuator 104, to which a steering handle 105 is assigned, and a steering actuator 106, as well as an arrangement 108 for carrying out the presented method. This arrangement 108 is implemented, for example, by software functions.

[0038] The arrangement 108 comprises an evaluation unit 110 configured to evaluate data on road conditions, in particular on upcoming road conditions, and to influence or adapt the steering characteristics of the steer-by-wire steering system 102 based on this evaluation. This is done, for example, by specifying at least one steering profile 114, which can be sent to the steering system 102 via a signal.

[0039] The illustration also shows an interface 112, via which data on the road conditions in the area of ​​the vehicle, and in particular on the planned route, can be received. This data can be provided by a cloud. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2020 212 447 A1

[0005]

Claims

[1] Method for operating a steering system (102) in a vehicle (100), in which data on a road condition of at least one road section ahead are evaluated and a steering characteristic of the steering system (102) is adapted as a function of this evaluation. [2] Method according to claim 1, in which a steer-by-wire steering system is operated. [3] Method according to claim 1, in which at least one steering profile is specified which is a representation of the determined steering characteristic, and this at least one steering profile is transferred to the steering and the steering characteristic is adapted according to the at least one steering profile. [4] Method according to claim 3, wherein the selection of the at least one steering profile is made on the basis of an exceedance of a limit value and / or an undershoot of the friction coefficient of the road surface. [5] Method according to one of claims 1 to 4, in which a steering ratio is reduced. [6] Method according to one of claims 1 to 5, wherein the steering characteristic describes a steering feel perceptible at a steering handle (105) of the steering (102). [7] Method according to claim 6, in which a higher steering assistance is applied in order to achieve a smoother steering (102). [8] Method according to claim 6 or 7, wherein a counter-holding torque on a feedback actuator (104) of the steering (102) is reduced. [9] Method according to one of claims 1 to 8, wherein the data are obtained from a friction coefficient map provided by a cloud. [10] Arrangement for operating a steering system (102) with an evaluation unit (110) which is designed to carry out a method according to one of claims 1 to 9.

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