Procedures for operating a vehicle and vehicle

Abstract

Method (100) for operating a vehicle (50) comprising a steer-by-wire system (10), wherein the steering angle of at least one vehicle wheel (51) of the vehicle (50) is changeable by a steering actuator (11) of the steer-by-wire system (10), the method (100) comprising: - Detecting (110) vehicle oversteer (50), - Acquiring (120) at least one driving parameter, wherein the driving parameter is characteristic for lateral guidance of the vehicle (50), - Performing (130) a steering intervention to reduce the steering angle of at least one vehicle wheel (51) in response to the oversteering of the vehicle (50), - Detection (140) of a change in at least one driving parameter resulting from the steering intervention, - Evaluating (150) the change in at least one driving parameter and providing an evaluation result and - Adjusting (160) the steering intervention depending on the evaluation result.

Description

[0001] The invention relates to a method for adjusting a steering angle in response to a detected oversteer of a vehicle, a vehicle designed to be operated according to such a method, a computer program product comprising instructions for executing such a method, a computer-readable medium on which such a computer program product is stored, and a data carrier signal that transmits such a computer program product.

[0002] The use of steer-by-wire systems in vehicles is generally known. Essentially, this involves a purely electrical connection between a control operated by the driver for lateral steering of the vehicle, in particular a steering wheel, and a steering gear, via which the steering angle of the vehicle wheels can be changed.

[0003] Systems for influencing vehicle lateral control are known, for example, from DE 197 23 841 A1, DE 10 2005 018 519 A1 or DE 10 2017 216 019 A1, which teaches how to reduce a steering angle in the event of detected oversteer of the vehicle.

[0004] Steer-by-wire systems allow driver assistance systems to intervene in the vehicle's lateral control, depending on the driving situation, to increase the safety of the vehicle occupants. Particularly in the event of oversteer, this can lead to significant steering interventions with steering angle changes of 10° or even 20°. A problem has been that the necessity of a steering intervention cannot always be definitively verified. This can result in a required steering intervention not being recognized, or an unjustified steering intervention being carried out incorrectly, in both cases significantly endangering the safety of the vehicle occupants.

[0005] It is therefore an object of the present invention to overcome at least one of the disadvantages described above, at least partially. In particular, it is an object of the invention to provide a method, a vehicle, a computer program product, and a data carrier signal that enable the safe operation of a vehicle to be supported and, in particular, to detect and correct unjustified steering interventions within the framework of a driver assistance system in a steer-by-wire system.

[0006] The foregoing problem is solved by a method with the features of independent claim 1, by a vehicle with the features of independent claim 7, by a computer program product with the features of independent claim 8, by a computer-readable medium with the features of independent claim 9, and by a data carrier signal with the features of claim 10. Further features and details of the invention will become apparent from the dependent claims, the description, and the drawings.Features and details described in connection with the method according to the invention naturally also apply in connection with the vehicle according to the invention and / or in connection with the computer program product according to the invention and / or in connection with the computer-readable medium according to the invention and / or in connection with the data carrier signal and vice versa, so that with regard to the disclosure of the individual aspects of the invention, mutual reference is always made or can always be made.

[0007] According to the invention, a method for operating a vehicle is provided, comprising a steer-by-wire system, wherein the steering angle of at least one vehicle wheel of the vehicle can be changed by at least one steering actuator of the steer-by-wire system, the method comprising: - Detecting vehicle oversteer, in particular by a control unit and / or detection unit, - Recording at least one driving parameter, wherein the driving parameter is characteristic for lateral guidance of the vehicle, in particular by a recording unit, - Performing a steering intervention to reduce the steering angle of at least one vehicle wheel in response to oversteer of the vehicle, in particular by the control unit and / or the steering actuator, - Detecting a change in at least one driving parameter resulting from the steering intervention, in particular by the detection unit, - Evaluating the change in at least one driving parameter and providing an evaluation result, in particular by the control unit and - Adjusting the steering intervention depending on the evaluation result, in particular by the control unit and / or the steer-by-wire system.

[0008] In other words, a method for operating a vehicle is proposed, wherein the vehicle comprises a steer-by-wire system by which the steering angle of at least one of the vehicle's wheels can be changed. Preferably, the vehicle is a two-track vehicle with a front axle and a rear axle, with two wheels arranged on each axle. It is preferably provided that the steering actuator allows the steering angle of the wheels on the front axle to be changed, particularly simultaneously or in a coupled manner.

[0009] According to the invention, vehicle oversteer is detected, in particular by a control unit and / or a detection unit. Furthermore, at least one driving parameter characteristic of, and especially current, lateral steering of the vehicle is detected, in particular by a detection unit. This means that the intensity of the vehicle's lateral steering can be derived from the driving parameter.

[0010] In response to the vehicle oversteering, a steering intervention, i.e., a change in the steering angle of at least one vehicle wheel, is carried out according to the invention. In this case, the steering intervention is carried out such that the steering angle of at least one vehicle wheel, in particular the wheels of a front axle of the vehicle, is reduced. A reduction in steering angle is understood here to mean a movement of the respective vehicle wheel in the direction of a position in which the wheel is located when the vehicle is traveling straight ahead. The steering intervention can preferably be carried out by a control unit and / or the steering actuator of the vehicle's steer-by-wire system. In particular, the steering actuator can be controlled by the control unit such that the steering actuator performs the steering intervention.The steering intervention is therefore not a steering intervention made by the driver, but a steering intervention in the sense of a driver assistance system provided by the present procedure.

[0011] According to the invention, a change in at least one driving parameter resulting from the steering input is detected, in particular by a detection unit. If multiple driving parameters are detected, a change resulting from the steering input can be determined for each driving parameter. For this purpose, the corresponding driving parameter can be detected again and compared qualitatively and / or quantitatively with the previously detected value. The change in the driving parameter(s) is evaluated, and an evaluation result is provided, in particular by a control unit. Depending on the evaluation result, the steering input is adjusted, in particular by a control unit and / or the steering actuator. In particular, the steering actuator can be controlled by the control unit in such a way that the steering input is adjusted as desired.Adjusting the steering intervention can involve maintaining a steering angle, increasing the steering angle, or decreasing the steering angle of at least one vehicle wheel, in particular the vehicle wheels of a front axle of the vehicle.

[0012] The method according to the invention offers the advantage that the vehicle's reaction to a steering intervention is immediately detected and evaluated, and any necessary correction of the steering intervention is carried out based on this evaluation. Within the scope of the invention, it was recognized that a steering intervention to stabilize an oversteering vehicle should not result in a significant change in the vehicle's lateral stability. A significant change in the vehicle's lateral stability can mean that the steering intervention was performed during a stable driving condition, i.e., that the vehicle's oversteer was incorrectly detected. A significant change in the vehicle's lateral stability also occurs if the steering intervention was too strong and the vehicle consequently deviates from the course intended by the driver.Therefore, the present procedure can support the safe operation of a vehicle by detecting and correcting unjustified steering interventions within the framework of a driver assistance system.

[0013] The evaluation result is preferably characteristic of the degree of change of the driving parameter(s). The evaluation result can be provided, for example, as an absolute and / or relative change with respect to at least one driving parameter. Additionally or alternatively, the evaluation result can be provided, with respect to at least one driving parameter, as a gradient, particularly a temporal one.

[0014] The procedure may be designed to be executed in the specified order. It may also be designed to execute at least some steps of the procedure simultaneously and / or repeatedly. Additionally or alternatively, the procedure may preferably be a computer-implemented method.

[0015] Within the scope of the invention, it may be advantageous that the detection of vehicle oversteer comprises the following: - Determining the vehicle's skew angle, - Comparing the sideslip angle with a sideslip angle limit, assuming that the vehicle will oversteer if the sideslip angle reaches or exceeds the sideslip angle limit.

[0016] The sideslip angle is defined here as the angle between the direction of motion of the vehicle, particularly at its center of gravity or at a rear axle, and the vehicle's longitudinal axis. It is possible for the determination of the sideslip angle to be model-based. Preferably, the model-based determination can be carried out using a vehicle dynamics model, in particular a single-track or two-track model. Known models can be used for this purpose. The vehicle dynamics model is defined as a functional relationship between at least one vehicle dynamics parameter and the sideslip angle, wherein the vehicle dynamics model determines the sideslip angle as an output parameter based on at least one vehicle dynamics parameter as an input parameter. At least one vehicle dynamics parameter can be acquired by at least one acquisition unit.Vehicle dynamics parameters can include, for example, vehicle accelerations, particularly longitudinal and / or lateral acceleration, and / or suspension travel at at least one wheel. Model-based determination of the sideslip angle offers the advantage of cost-effective implementation. Alternatively or additionally, the vehicle's sideslip angle can be measured, particularly using sensors. This offers the advantage of high accuracy.

[0017] It is preferable that the maximum permissible sideslip angle is greater than 2°, in particular at least 3°, preferably at least 4°, and most preferably at least 5°. Sideslip angles greater than 3° are often perceived by the driver or occupants of the vehicle as an abnormal driving situation. At sideslip angles of 10° or greater, the vehicle is in a drift state that can only be controlled by experienced drivers.

[0018] Additionally or alternatively, it may be advantageously provided that the detection of vehicle oversteer includes the following: - Determining the yaw rate of the vehicle around a vehicle vertical axis, - Comparing the yaw rate with a yaw rate limit, assuming that the vehicle will oversteer if the yaw rate reaches or exceeds the yaw rate limit.

[0019] To detect the yaw rate, it may be provided that at least one detection unit comprises at least one inertial sensor, in particular a rotation rate sensor or yaw rate sensor.

[0020] It can be provided that the strength of the steering intervention, i.e., the quantitative reduction of the steering angle, is proportional to the measured sideslip angle of the vehicle or to the deviation of the sideslip angle from the sideslip angle limit. In this context, a linear or non-linear proportionality is conceivable. In particular, it is conceivable that the proportionality can be adjusted by specifying a proportionality curve. For example, a vehicle user could select a proportionality curve from a number of vehicle-provided proportionality curves to influence the vehicle's handling as desired. At least one of the vehicle-provided proportionality curves could also be modifiable by the vehicle user to further enhance the individuality of the handling.

[0021] It can be provided that the strength of the steering intervention, i.e., the quantitative reduction of the steering angle, is proportional to the measured yaw rate of the vehicle or to the deviation of the yaw rate from the yaw rate limit. In this context, a linear or non-linear proportionality is conceivable. In particular, it is conceivable that the proportionality can be adjusted by specifying a proportionality curve. For example, a vehicle user could select a proportionality curve from a number of vehicle-provided proportionality curves to influence the vehicle's handling as desired. At least one of the vehicle-provided proportionality curves could also be modifiable by the vehicle user to further enhance the individuality of the handling.

[0022] It may be provided that at least one of the following is included: - Selection of a proportionality characteristic curve by a user, in particular the driver, of the vehicle, wherein the proportionality characteristic curve establishes a relationship between the determined sideslip angle of the vehicle or the deviation of the sideslip angle from the sideslip angle limit value and / or the determined yaw rate of the vehicle or the deviation of the yaw rate from the yaw rate limit value on the one hand and the strength of the steering intervention on the other hand and / or - Determining the strength of the steering intervention based on the proportionality characteristic curve.

[0023] Within the scope of the invention, it may be provided that the acquisition of at least one driving parameter comprises the following: - Detecting the lateral acceleration of the vehicle, - Detection of a steering force applied to a steering gear of the steer-by-wire system.

[0024] In other words, a driving parameter characteristic of lateral acceleration can be the lateral acceleration of the vehicle or a steering force applied to a steering gear of the steer-by-wire system. The steering force is, in particular, proportional to a restoring torque applied to at least one wheel. The use of lateral acceleration and / or steering force has proven particularly effective in relation to the present invention for verifying the justification of a steering intervention.

[0025] It is also conceivable that adjusting the steering intervention includes the following: - Maintaining or reducing the steering angle of at least one vehicle wheel, provided that the change in at least one driving parameter is less than or equal to a specified change limit.

[0026] In other words, the steering intervention is maintained or even intensified if the change in at least one driving parameter, or in particular all driving parameters, remains below a predetermined change threshold or reaches but does not exceed it. Therefore, if no or no significant change in the vehicle's lateral stability is detected despite the steering intervention, the intervention was justified, and the vehicle will henceforth be driven with greater stability, but still on the course desired by the driver.

[0027] It is also conceivable that adjusting the steering intervention includes the following: - Increasing the steering angle of at least one vehicle wheel, provided that the change in at least one driving parameter is greater than or equal to a specified change limit.

[0028] In other words, the steering intervention is at least partially withdrawn or weakened if the change in at least one driving parameter, or in particular all driving parameters, reaches or exceeds a predetermined limit value. In this case, there is a significant change in the vehicle's lateral stability, which suggests an unjustified steering intervention or a deviation of the vehicle from the course desired by the driver.

[0029] The above-mentioned problem is further solved by a vehicle according to the invention, comprising a steer-by-wire system, wherein the steering angle of at least one vehicle wheel can be changed by a steering actuator of the steer-by-wire system, and wherein the vehicle is configured to be operated according to a method according to the invention, in particular according to a method according to any one of claims 1 to 6. This results in the same advantages with respect to a vehicle according to the invention as have already been described with respect to a method according to the invention. Preferably, the vehicle can be configured as a car, in particular a passenger car. Alternatively, the vehicle can be configured as a commercial vehicle, in particular a truck.

[0030] The vehicle, in particular the steer-by-wire system, can include at least one control unit.

[0031] At least one control unit and / or acquisition unit may include data processing means. The data processing means may preferably include at least one processor and / or at least one data storage device and / or at least one non-volatile data storage device. Additionally or alternatively, at least one control unit and / or acquisition unit may include at least one communication interface for establishing wireless or wired communication.

[0032] At least one detection unit can preferably comprise at least one sensor element for detecting a driving parameter and / or vehicle dynamics parameter. At least one sensor element can be configured as a yaw rate sensor for detecting the vehicle's yaw rate and / or an acceleration sensor for detecting the vehicle's lateral and / or longitudinal acceleration and / or a force sensor for detecting steering force.

[0033] In particular, it may be provided that at least one control unit and at least one sensor unit and / or at least one steering actuator can be brought into a communication link, at least temporarily, and in particular a bidirectional one. In this way, data, especially sensor data, can be transmitted from the sensor unit to the control unit and further processed by the control unit. Based on this data, the control unit can generate control signals and transmit them to the steering actuator in order to adjust a steering angle at at least one wheel of the vehicle.

[0034] The steer-by-wire system can, in particular, comprise a steering gear and at least one steering actuator operatively connected to the steering gear. The steering actuator is preferably configured to adjust the steering angle of at least one vehicle wheel via the steering gear. The steering gear can preferably be designed as a rack and pinion drive.

[0035] Preferably, the steer-by-wire system comprises a steering handle for the driver of the vehicle, in particular a steering wheel, and a steering angle sensor for detecting a steering angle at the steering handle. The steering angle sensor may be directly or indirectly connected to the steering actuator via a wireless or wired communication link, so that a steering angle corresponding to the steering angle detected at the steering handle can be set at at least one vehicle wheel by the steering actuator.

[0036] The above-mentioned problem is further solved by a computer program product according to the invention, comprising instructions that cause a vehicle according to the invention, in particular a vehicle according to claim 7, to execute a method according to the invention, in particular a method according to any one of claims 1 to 6. This results in the same advantages with respect to a computer program product according to the invention as have already been described with respect to a method and / or a vehicle according to the invention.

[0037] The above problem is further solved by a computer-readable medium, in particular a storage medium, on which a computer program product according to the invention, in particular a computer program product according to claim 8, is stored. This results in the same advantages with respect to a computer-readable medium according to the invention as have already been described with respect to a method and / or a vehicle and / or a computer program product according to the invention.

[0038] Furthermore, the above-mentioned problem is solved by a data carrier signal that transmits a computer program product according to the invention, in particular a computer program product according to claim 8. This results in the same advantages with respect to a data carrier signal according to the invention as have already been described with respect to a method and / or a vehicle according to the invention and / or a computer program product according to the invention and / or a computer-readable medium according to the invention.

[0039] Further advantages, features, and details of the invention will become apparent from the following description, in which several embodiments of the invention are described in detail with reference to the drawings. The features mentioned in the claims and in the description can each be essential to the invention individually or in any combination. The following is shown: Fig. 1 a schematic view of a procedure, Fig. 2 a schematic view of a vehicle and Fig. 3 A schematic view of a steer-by-wire system.

[0040] The figures use identical reference numerals for the same technical features, even for different embodiments.

[0041] The Fig. Figure 1 shows a schematic view of a method 100 for operating a vehicle 50, comprising a steer-by-wire system 10, wherein the steering angle of at least one vehicle wheel 51 of the vehicle 50 can be changed by a steering actuator 11 of the steer-by-wire system 10, the method 100 comprising: - Detect 110 of vehicle oversteer 50, - Capture 120 at least one driving parameter, where the driving parameter is characteristic for lateral guidance of the vehicle 50, - Performing 130 a steering intervention to reduce the steering angle of at least one vehicle wheel 51, - Detecting 140 of a change in at least one driving parameter resulting from the steering intervention, - Evaluate 150 of the change in at least one driving parameter and provide an evaluation result and - Adjusting the steering intervention 160 depending on the evaluation result.

[0042] Fig. Figure 2 shows a schematic view of a vehicle 50 as well as a representation of the vehicle's longitudinal axis X, the vehicle's transverse axis Y and the vehicle's vertical axis Z. The vehicle 50 comprises a Fig. 3. A steer-by-wire system 10, shown in more detail, and four vehicle wheels 51, wherein two vehicle wheels 51 are arranged on a front axle and two on a rear axle of the vehicle 50. The steering angle of the vehicle wheels 51 of the front axle is adjustable by a steering actuator 11 of the steer-by-wire system 10.

[0043] Out of Fig. Figure 3 shows that the steer-by-wire system 10 comprises a steering gear 12 and at least one steering actuator 11 operatively connected to the steering gear 12. The steering actuator 11 is designed to adjust the steering angle of at least one vehicle wheel 51 via the steering gear 12. The steering gear 12 is designed as a rack and pinion drive.

[0044] The steer-by-wire system 10 further comprises a steering handle 13 for initiating a steering movement by a driver of the vehicle 50 and a steering angle sensor 14 for detecting a steering angle at the steering handle 13. The steering angle sensor 14 is directly or indirectly in communication with the steering actuator 11, so that a steering angle corresponding to the steering angle detected at the steering handle 13 can be set at at least one vehicle wheel 51 by the steering actuator 11. Reference symbol list 10 Steer-by-Wire System 11 Steering actuator 12 Steering gear 13 Steering handle 14 Steering angle sensor 50 vehicles 51 vehicle wheel 100 procedures 110 Detect 120 Capture 130 Perform 140 Capture Evaluate 150 160 Adjust X Vehicle longitudinal axis Y vehicle transverse axis Z vehicle vertical axis

Claims

[1] Method (100) for operating a vehicle (50) comprising a steer-by-wire system (10) wherein the steering angle of at least one vehicle wheel (51) of the vehicle (50) is changeable by a steering actuator (11) of the steer-by-wire system (10), the method (100) comprising: - Detecting (110) vehicle oversteer (50), - Acquiring (120) at least one driving parameter, wherein the driving parameter is characteristic for lateral guidance of the vehicle (50), - Performing (130) a steering intervention to reduce the steering angle of at least one vehicle wheel (51) in response to the oversteering of the vehicle (50), - Detection (140) of a change in at least one driving parameter resulting from the steering intervention, - Evaluating (150) the change in at least one driving parameter and providing an evaluation result and - Adjusting (160) the steering intervention depending on the evaluation result. [2] Method (100) according to claim 1, characterized by , that detecting (110) vehicle oversteer (50) includes the following: - Determining the vehicle's skew angle (50°), - Comparing the swimming angle with a swimming angle limit value, where oversteer of the vehicle (50) is assumed if the sideslip angle reaches or exceeds the sideslip angle limit. [3] Method (100) according to any one of the preceding claims, characterized by , that detecting (110) vehicle oversteer (50) includes the following: - Determining the yaw rate of the vehicle (50) about a vehicle vertical axis (Z), - Comparing the yaw rate with a yaw rate limit, where oversteering of the vehicle (50) is assumed if the yaw rate reaches or exceeds the yaw rate limit. [4] Method (100) according to any one of the preceding claims, characterized by , that the acquisition (120) of at least one driving parameter includes the following: - Recording the lateral acceleration of the vehicle (50) as a driving parameter and / or - Capturing a steering force applied in a steering gear (12) of the steer-by-wire system (10) as a driving parameter. [5] Method (100) according to any one of the preceding claims, characterized by , that adjusting (160) the steering intervention includes the following: - Maintaining or reducing the steering angle of at least one vehicle wheel (51), provided that the change in at least one driving parameter is less than or equal to a specified change limit. [6] Method (100) according to any one of the preceding claims, characterized by, that adjusting (160) the steering intervention includes the following: - Increasing the steering angle of at least one vehicle wheel (51), provided that the change in at least one driving parameter is greater than or equal to a specified change limit value. [7] Vehicle (50) comprising a steer-by-wire system (10), wherein the steering angle of at least one vehicle wheel (51) is changeable by a steering actuator (11) of the steer-by-wire system (10) and wherein the vehicle (50) is configured to be operated according to a method (100) according to one of the preceding claims. [8] Computer program product comprising instructions that cause a vehicle (50) according to the preceding claim to execute a method (100) according to any one of claims 1 to 6. [9] Computer-readable medium on which a computer program product according to the preceding claim is stored. [10] Data carrier signal that transmits a computer program product according to claim 9.

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