Method for influencing a steering device of a vehicle

Abstract

The invention relates to a method (200) for influencing a steering device (10) of a vehicle (100), the steering device (10) comprising at least one individually controllable wheel steering-angle adjuster (12, 14), and the vehicle (100) comprising a braking device (20) having at least one individually controllable brake (22, 24) per wheel steering-angle adjuster (12, 14). The method comprises: detecting (202) a defective wheel steering-angle adjuster (12) of the steering device (10); detecting (204) a braking maneuver initiated by a user of the vehicle (100) and / or a driver assistance system (40) of the vehicle (100), which braking maneuver is represented by a specific braking effect (22a, 24a) to be generated by the at least one individually controllable brake (22, 24); determining (206) that the braking effect (22a) associated with the at least one individually controllable brake (22) of the defective wheel steering-angle adjuster (12) is maintained (208) or reduced (210) depending on at least one parameter (52) which characterizes and / or initializes the braking maneuver to be initiated.

Description

[0001] Description

[0002] title

[0003] Method for influencing a vehicle's steering system

[0004] State of the art

[0005] The invention relates to a method for influencing a steering device, in particular a wheel steering angle adjuster of the steering device, of a vehicle.

[0006] In normal vehicle operation, wheel steering angle adjusters, such as those in a steer-by-wire system, move synchronously to control the vehicle. For example, if a vehicle has two steerable front wheels whose steering angles are set by individually controllable wheel steering angle adjusters, and one of these adjusters fails or becomes passive, the vehicle remains steerable. In this case, the wheel associated with the passive wheel steering angle adjuster, which is free of torque, positions itself in a neutral position when driving straight ahead and in a curve due to externally acting lateral forces. The positioning method depends heavily on the front axle design, but is generally such that, under forces exceeding the passive displacement force, the wheel associated with the passive wheel steering angle adjuster lags behind the steering angle of the wheel associated with the active wheel steering angle adjuster by a delay.

[0007] In certain situations, such as heavy braking, heavy acceleration or reversing, the wheel assigned to the passive steering angle adjuster may fold away or inwards into a mechanical end stop; one reason for this is axle characteristics such as toe-in.

[0008] Accordingly, a method is desirable that prevents a wheel associated with a passive wheel steering angle adjuster from folding away and yet has no safety-critical effects on the driving behavior of a vehicle.

[0009] Disclosure of the invention

[0010] This is achieved through a process and a vehicle in accordance with the independent claims.

[0011] The method for influencing a steering system of a vehicle, wherein the steering system comprises at least one individually controllable wheel steering angle actuator, and wherein the vehicle comprises a braking system with at least one individually controllable brake per wheel steering angle actuator, comprises: detecting a defective wheel steering angle actuator of the steering system; detecting a braking maneuver initiated by a user of the vehicle and / or a driver assistance system of the vehicle, which is represented by a specific braking effect to be generated by the at least one individually controllable brake; and determining whether the braking effect assigned to the at least one individually controllable brake of the defective wheel steering angle actuator is maintained or reduced, depending on at least one parameter that characterizes and / or initializes the braking maneuver to be initiated.This prevents a wheel associated with the defective steering angle adjuster from folding away, thereby improving the vehicle's handling. Furthermore, full braking force can be applied in safety-critical driving situations to mitigate these situations.

[0012] The procedure may include maintaining the specific braking effect associated with the defective wheel steering angle actuator if at least one parameter characterizes a braking maneuver to be initiated that is necessary to mitigate a safety-critical driving situation, in particular full braking or emergency braking. This accepts the folding away of the wheel associated with the defective wheel steering angle actuator in order to access the full braking effect and mitigate the safety-critical driving situation. The vehicle's safety is thus increased. Full braking or emergency braking is characterized by a braking deceleration of approximately 7.5 to 10 m / s², depending on the vehicle type. 2and values ​​above. During emergency or full braking, the maximum possible braking force is generally applied. A safety-critical driving situation is characterized, for example, by the fact that a collision, an accident, or resulting uncontrollable driving behavior is imminent, unavoidable, or can only be avoided by means of full braking, emergency braking, or hazard braking.

[0013] It can be provided that the at least one parameter includes at least one property of a brake pedal actuation, in particular pedal pressure and / or pedal gradient and / or pedal jerk, whereby the specific braking effect associated with the defective wheel steering angle actuator is maintained when the at least one property of the brake pedal actuation exceeds a predefinable threshold. This parameter characterizes a braking maneuver initiated by the vehicle user. The properties of a brake pedal actuation represent a braking maneuver to be initiated by the user. These properties are easy to obtain and quick to evaluate.

[0014] For example, an operation with high pedal pressure and / or a high pedal gradient and / or a high pedal jerk represents an emergency stop or full stop.

[0015] It may be provided that at least one parameter includes a characteristic value provided by the driver assistance system that characterizes a vehicle environment, maintaining the specific braking effect associated with the defective wheel steering angle actuator if the characteristic value characterizes an environment in which an accident appears unavoidable or would be unavoidable without maintaining the braking effect. This can also mitigate a safety-critical driving situation that the vehicle user does not recognize or that occurs during autonomous vehicle operation, thereby increasing vehicle safety.

[0016] The procedure may include reducing the specific braking effect associated with the defective wheel steering angle actuator if at least one parameter characterizes a braking maneuver to be initiated in which the braking effect associated with the defective wheel steering angle actuator is not maintained, in particular a braking maneuver that does not serve to mitigate a safety-critical driving situation, especially light or simple braking in an ordinary traffic situation, whereby the braking effect associated with the defective wheel steering angle actuator is reduced in such a way as to prevent a wheel of the vehicle coupled to the defective wheel steering angle actuator from folding away. By reducing the braking effect associated with the defective wheel steering angle actuator, the vehicle remains drivable and generally controllable despite the defective wheel steering angle actuator.The braking effect associated with the defective wheel steering angle adjuster is reduced particularly when a driving situation is not safety-critical, i.e., no full braking, emergency braking or hazard braking is necessary to prevent an accident, a collision or uncontrollable driving behavior.

[0017] It may be provided that the vehicle has at least two individually controllable wheel steering angle actuators and that the procedure includes counter-steering by the non-defective wheel steering angle actuator when the braking effect associated with the defective wheel steering angle actuator is reduced. This can reduce any impairment of the vehicle's handling resulting from an asymmetrical distribution of braking effects.

[0018] It may be possible to adjust the braking control strategy of the braking maneuver to be initiated if the braking effect associated with the defective wheel steering angle actuator is reduced. This can reduce any impairment of the vehicle's handling resulting from an asymmetrical distribution of braking effects.

[0019] The procedure may include warning the vehicle user, particularly through visual, auditory, or haptic sensory input, and / or locking the vehicle's direction of travel when a defective wheel steering angle adjuster is detected. This informs the user of the defective wheel steering angle adjuster, allowing them to adjust their behavior accordingly. Locking the direction of travel, for example, prevents accidental reversing, which could cause the wheel to fold away and subsequently prevent forward travel.

[0020] The procedure may include reducing the drive torque of a wheel associated with the defective steering angle actuator, thus preventing uncontrolled folding of the wheel associated with the defective steering angle actuator. This prevents the wheel from folding due to high drive acceleration, and the vehicle remains drivable despite the defective steering angle actuator.

[0021] The vehicle according to the invention comprises: a steering device, in particular a steer-by-wire steering device, with at least one individually controllable wheel steering angle actuator that sets a wheel steering angle of the vehicle; a braking device, in particular a brake-by-wire braking device, which comprises at least one individually controllable brake, wherein each wheel steering angle actuator is assigned a brake that generates a braking effect assigned to the wheel steering angle actuator, and wherein the steering device and the braking device are configured to carry out the method according to the invention.

[0022] Further advantageous embodiments will become apparent from the drawing and the following description. The drawing shows:

[0023] Figure 1 shows a schematic representation of a vehicle comprising a steering device and a braking device;

[0024] Figure 2 shows a flowchart of a method for operating the steering and braking devices;

[0025] Figure 3 shows a flowchart of one embodiment of the method.

[0026] Figure 1 shows a schematic representation of a vehicle 100 comprising a steering system 10 and a braking system 20. The steering system 10 is specifically designed as a steer-by-wire system with at least one individually controllable wheel steering angle adjuster that sets the steering angle of one wheel of the vehicle 100. It is conceivable that the steering system 10 includes a wheel steering angle adjuster for each wheel of the vehicle 100 to be controlled. For example, the steering system 10 comprises two wheel steering angle adjusters, a first wheel steering angle adjuster 12 and a second wheel steering angle adjuster 14, each assigned to a first wheel 102 and a second wheel 104 of the vehicle, respectively, and coupled to the vehicle by means of a functional connection. The wheel steering angle adjusters 12 and 14 are configured to set the steering angle of the wheels 102 and 104, thereby controlling the vehicle 100.The wheel steering angle adjusters 12 and 14 can, for example, comprise an actuator and a gearbox. The actuator is typically an electric drive and generates a rotary motion. This motion can be converted into a translational motion by means of the gearbox, which is used to change the angular position of the wheel, in the form of the wheel steering angle. The rack can be coupled to the rotor of the actuator in various ways, e.g., as a pinion-rack or belt-ball screw drive. A purely rotary gearbox concept is also conceivable, e.g., a planetary gear, harmonic drive, etc., between the rotor of the actuator and the pivot axis of the steered wheel. The wheel steering angle adjusters 12 and 14 are generally controllable individually and independently of each other, so that they can, for example, set different wheel steering angles.

[0027] The wheel steering angle actuators 12 and 14 are assigned to a front axle of the vehicle 100, but can alternatively be provided on a rear axle of the vehicle 100. It is also conceivable that the vehicle 100 comprises more than two wheel steering angle actuators 12 and 14, for example in the form of a combined front and rear axle steering system. For controlling the vehicle 100, it includes, for example, a control device 106, such as a hand torque actuator of a steer-by-wire steering system with a steering wheel or a joystick (e.g., an active one), by means of which a user of the vehicle 100 can influence the direction of travel of the vehicle 100 in conjunction with the steering device 10. Furthermore, the vehicle 100 may include a driver assistance system 40, which, for example, enables autonomous driving and can control the vehicle 100 by means of the steering device 10.The driver assistance system 40 includes a sensor device 42 that can detect the vehicle's surroundings. The wheel steering angle actuators 12 and 14 can be configured as decentralized tie rod actuators with separate housings, so that each wheel 102 and 104 is assigned its own wheel steering angle actuator 12 and 14. Alternatively, the steering device 10 can include wheel steering angle actuators 12 and 14 arranged in a common housing, but with separate control units and gearboxes.

[0028] The braking device 20 is specifically designed as a brake-by-wire braking device comprising at least one individually controllable brake 22 and 24. Each wheel steering angle actuator 12 and 14 is assigned one of the brakes 22 and 24, respectively, which each generate a braking effect 22a and 24a corresponding to the wheel steering angle actuators 12 and 14. The brakes 22 and 24 are, for example, designed as disc brakes and serve to apply a braking torque to the wheels 102 and 104 of the vehicle 100 in the event that a braking maneuver needs to be initiated. The braking effects 22a and 24a are symbolically represented as arrows and are generated, for example, by the braking torque or a braking pressure of the brakes 22 and 24 of the braking device 20.

[0029] The braking device 20 can be operated by the user, for example, by means of a brake control device 108, for example by generating hydraulic pressure in the brake circuit or by determining a signal, such as pedal travel or pedal force, and can execute vehicle dynamics controls, such as an Electronic Stability Program (ESP) and / or an Anti-lock Braking System (ABS) application and / or implement other brake control strategies. It may also be provided that the driver assistance system 40 can operate the braking device 20.

[0030] The braking device 20 is designed to execute a braking maneuver by means of braking effects 22a and 24a. The braking maneuver is initiated by the user via the brake pedal 108 or by the driver assistance system 40. If neither a wheel steering angle actuator 12 nor 14 is defective, i.e., during normal operation, the braking maneuver to be initiated is detected and the braking device 20 implements it by means of braking effects 22a and 24a, whereby the braking effects 22a and 24a can differ, even during normal operation, depending on the driving situation and braking control strategy.

[0031] The braking maneuver can, for example, be an emergency stop or full stop, in which the maximum possible braking performance or deceleration is to be achieved. Accordingly, in this case, the braking effects 22a and 24a must be maximized, for example, by means of maximum brake pressure or braking torque. Emergency stops or full stops are characterized, for example, by decelerations, depending on the vehicle type, on a surface with a high coefficient of friction between a tire and the road surface, ranging from 7.5 to 10 m / s². 2 and more. Emergency braking or full braking is initiated by the user or the driver assistance system when a dangerous or safety-critical driving situation, such as an accident, appears unavoidable or is unavoidable. For simplicity, these braking maneuvers can be collectively referred to as emergency braking.

[0032] Other braking maneuvers include stopping at a traffic light or in a traffic jam, as well as braking with low decelerations of, for example, less than 7.5 to 10 m / s². 2 , typically with braking decelerations between 1 and 4 m / s² 2 These braking maneuvers are initiated when there is no dangerous or safety-critical driving situation, and, for example, no accident is imminent. For simplicity, these braking maneuvers are referred to as simple or light braking maneuvers.

[0033] For example, the vehicle 100 includes a computing unit 50, which is designed as a central control unit and networks the steering system 10, the braking system 20, and the driver assistance system 40. It may be provided that the braking system 20 and the steering system 10 are networked via a separate control unit or directly with each other.

[0034] The vehicle 100 can include a device 30 for distributing a drive torque, in particular a torque vectoring device. This device is configured to provide each wheel 102 and 104 of the vehicle 100 with an individual drive torque. In the example shown, the first wheel steering angle actuator 12 is defective, which is represented by a lightning bolt symbol for illustration. Defective means, for example, that an actuator of the wheel steering angle actuator 12 has failed and can therefore no longer generate any actuating torque.

[0035] The defective wheel steering angle actuator 12 can be detected by the steering unit 10 or the processing unit 50. As soon as a defective wheel steering angle actuator is detected, the processing unit 50, a decentralized control unit, or the steering unit 10 determines, based on at least one parameter 52, whether a braking effect 22a associated with the defective wheel steering angle actuator 12 is adjusted or maintained. The at least one parameter 52 characterizes a braking maneuver to be initiated, which is initiated, for example, by a user using the brake pedal 108 and / or by the driver assistance system 40.

[0036] Figure 2 shows a method 200 for operating the steering device 10 and the braking device 20. The method can be executed, for example, by the computing unit 50 or by another control unit.

[0037] In step 202, it is detected whether a wheel steering angle actuator 12, 14 is defective. In the example shown, the wheel steering angle actuator 12 is defective. In step 204, a braking maneuver to be initiated is detected. The braking maneuver can be initiated by a user via the brake pedal 108 and / or by a driver assistance system 40 and / or be a system reaction of the vehicle 100 according to the standard of the German Institute for Standardization DIN 70065:2023. The braking device 10 then implements this braking maneuver by means of the brakes 22 and 24 and the braking effects 22a and 24a. The braking maneuver to be initiated is characterized by at least one parameter 52, which indicates whether it is a simple braking maneuver or an emergency braking maneuver.

[0038] The at least one parameter 52 comprises at least one property of the actuation of the brake pedal 108, in particular pedal pressure and / or pedal gradient and / or pedal jerk, wherein the specific braking effect 22a associated with the defective wheel steering angle actuator 12 is maintained if the at least one property of the actuation of the brake pedal 108 exceeds a predefinable threshold value. The threshold value may be composed of a combination of properties of the actuation of the brake pedal 108. High pedal pressure and / or a high pedal gradient, in the form of a rapid change in the actuation speed or position of the brake pedal, and / or a high pedal jerk indicate that emergency braking should be initiated.

[0039] The at least one parameter 52 comprises, alternatively or additionally to the at least one property of an actuation of the brake pedal 108, at least one characteristic value provided by the driver assistance system 40 that characterizes an environmental situation of the vehicle 100. The specific braking effect 22a associated with the defective wheel steering angle actuator 12a is maintained if the at least one characteristic value characterizes an environmental situation in which an accident appears unavoidable or is unavoidable without maintaining the specific braking effect 22a associated with the defective wheel steering angle actuator 12a. The driver assistance system 40 uses the sensor device 42 and, for example, algorithms for evaluating data provided by the sensor device 42 to detect the environmental situation of the vehicle 100.Examples include an emergency brake assist system, a Collision Avoidance System (CAS), a pre-crash system, a forward collision warning system (FCW), an autonomous emergency braking (AEB) system and / or a collision mitigation system.

[0040] It may be provided that parameter 52 characterizes the braking maneuver to be initiated by a combination of at least one characteristic value and at least one property of an actuation of the brake pedal 108. It is conceivable that parameter 52 characterizes an emergency braking maneuver if at least one property of an actuation of the brake pedal 108 or at least one characteristic value characterizes an emergency braking maneuver.

[0041] In step 206, depending on parameter 52, it is determined that the braking effect 22a assigned to the at least one individually controllable brake 22 of the defective wheel steering angle actuator 12 is maintained in step 208 or reduced in step 210, depending on the at least one parameter 52 that characterizes and / or initializes the braking maneuver to be initiated.

[0042] The specific braking effect 22a assigned to the defective wheel steering angle actuator 12 is maintained 208 if at least one parameter 52 characterizes a braking maneuver to be initiated that is required to defuse a safety-critical driving situation, in particular full braking or emergency braking. The specific braking effect 22a assigned to the defective wheel steering angle actuator 12 corresponds to the braking effect that would be provided in normal operation with a functioning wheel steering angle actuator 12, as illustrated by the reference numeral 22a".

[0043] The braking effect 22a associated with the defective wheel steering angle actuator 12 is reduced 210 when at least one parameter 52 characterizes a braking maneuver to be initiated in which the braking effect 22a, 22a" associated with the defective wheel steering angle actuator 12 is not maintained, in particular a simple braking maneuver. The braking effect 22a associated with the defective wheel steering angle actuator 12 is reduced in such a way as to prevent the wheel 102 of the vehicle 100, coupled to the defective wheel steering angle actuator 12, from folding away. It is provided that the reduction 210 includes switching off the braking effect 22a at the defective wheel steering angle actuator 12a. In Figure 2, a reduced braking effect 22a is designated by the reference numeral 22a'.

[0044] Figure 3 shows an embodiment of the method 200. This embodiment includes a step 212 in which the non-defective wheel steering angle actuator 14 is counter-steered when the braking effect 22a associated with the defective wheel steering angle actuator 12 is reduced. For this purpose, the vehicle 100 comprises at least two individually controllable wheel steering angle actuators 12 and 14. Reducing 210 the braking effect 22a associated with the defective wheel steering angle actuator 12 results in an asymmetrical distribution of braking effects, which affects the driving behavior of the vehicle 100. This influence can be reduced or compensated for by counter-steering 212 of the non-defective wheel steering angle actuator 14. The method 200 may include warning the user of the vehicle 100, in particular by visual, acoustic, or haptic sensory impressions, when a defective wheel steering angle actuator 12 is detected 202.The warning can be implemented, for example, by a vibration of the operating device 106 and / or by an increased stiffness of the operating device 106 and / or by visual and acoustic warning signals.

[0045] Furthermore, it is conceivable that the procedure includes blocking a reversal of the vehicle 100's direction of travel if a defective wheel steering angle adjuster 12 is detected. A reversal of the direction of travel, in particular a reverse movement initiated from forward travel of the vehicle 100, greatly increases the probability of the wheel 102 coupled to the defective wheel steering angle adjuster 12 folding away. With a folded-away wheel, further travel or maneuvering is no longer possible, and the vehicle 100 is inoperable.

[0046] In one embodiment, the method 200 comprises reducing the drive torque of a wheel 102 associated with the defective steering angle actuator 12, thus preventing the wheel 102 associated with the defective steering angle actuator 12 from folding in. The drive torque of the wheel 102 associated with the defective steering angle actuator 12 can be reduced by means of the drive torque distribution device 30 or by reducing or limiting the propulsion request of the vehicle 100 user, which the user expresses, for example, by means of an accelerator pedal position, through an interface of an Electronic Stability Program (ESP) to a drive management system of the vehicle. During high accelerations of the vehicle 100, the probability of the wheel 102 associated with the defective steering angle actuator 12 folding in increases.

[0047] It may be provided that a speed, in particular a maximum speed of the vehicle 100, is reduced, for example in accordance with German Institute for Standardization DIN 70065:2023, as soon as a defective wheel steering angle adjuster 12 is detected 202.

Claims

Claims 1. Method (200) for influencing a steering device (10) of a vehicle (100), wherein the steering device (10) comprises at least one individually controllable wheel steering angle actuator (12, 14), and the vehicle (100) comprises a braking device (20) with at least one individually controllable brake (22, 24) per wheel steering angle actuator (12, 14), comprising: Detection (202) of a defective wheel steering angle adjuster (12) of the steering device (10); Detection (204) of a braking maneuver initiated by a user of the vehicle (100) and / or a driver assistance system (40) of the vehicle (100), which is represented by a specific braking effect (22a, 24a) to be generated by at least one individually controllable brake (22, 24); Determine (206) that the braking effect (22a) assigned to the at least one individually controllable brake (22) of the defective wheel steering angle actuator (12) is maintained (208) or reduced (210), depending on at least one parameter (52) that characterizes and / or initializes the braking maneuver to be initiated.

2. The method (200) according to claim 1, comprising maintaining (208) the specific braking effect (22a) associated with the defective wheel steering angle adjuster (12) when the at least one parameter (52) characterizes a braking maneuver to be initiated, in particular a full braking or an emergency braking maneuver, which is required to defuse a safety-critical driving situation.

3. The method (200) according to claim 2, wherein the at least one parameter (52) comprises at least one property of an actuation of a brake pedal (108), in particular a pedal pressure and / or a pedal gradient and / or a pedal jerk, wherein the defective wheel steering angle adjuster (12a) the specific braking effect (22a) associated with it is maintained if at least one characteristic of the actuation of the brake pedal (108) exceeds a predeterminable threshold.

4. The method (200) according to one of claims 2 or 3, wherein the at least one parameter (52) comprises at least one characteristic value provided by the driver assistance system (40) and which characterizes an environmental situation of the vehicle (100), wherein the specific braking effect (22a) associated with the defective wheel steering angle actuator (12a) is maintained when the at least one characteristic value characterizes an environmental situation in which an accident appears unavoidable or is unavoidable without maintaining (208).

5. The method (200) according to one of claims 2 to 4, comprising reducing (210) the specific braking effect (22a) associated with the defective wheel steering angle actuator (12a) when the at least one parameter (52) characterizes a braking maneuver to be initiated in which the braking effect associated with the defective wheel steering angle actuator (12) is not maintained, in particular a braking maneuver that does not serve to defuse a safety-critical driving situation, in particular a light or simple braking in an ordinary traffic situation, wherein the braking effect (22a) associated with the defective wheel steering angle actuator (12) is reduced in such a way as to prevent a wheel (102) of the vehicle (100) coupled to the defective wheel steering angle actuator (12) from folding away.

6. The method (200) according to claim 5, wherein the vehicle comprises at least two individually controllable wheel steering angle actuators (12, 14), comprising counter-steering (212) of the non-defective wheel steering angle actuator (14) when the braking effect (22a) associated with the defective wheel steering angle actuator (12) is reduced (210).

7. The method (200) according to one of claims 5 or 6, wherein a brake control strategy of the braking maneuver to be initiated is adapted when the braking effect (22a) associated with the defective wheel steering angle actuator (12) is reduced (210).

8. The method (200) according to one of the preceding claims, comprising warning the user of the vehicle (100), in particular by visual, acoustic or haptic sensory impressions and / or blocking a reversal of a direction of travel of the vehicle (100) when a defective wheel steering angle adjuster (12) is detected.

9. The method (200) according to one of the preceding claims, comprising reducing a drive torque of a wheel (102) associated with the defective wheel steering angle adjuster (12, 14) such that a folding away of the wheel (102) associated with the defective wheel steering angle adjuster (12) is prevented.

10. Vehicle (100) comprising: a steering device (10), in particular a steer-by-wire steering device, with at least one individually controllable wheel steering angle actuator (12, 12) that sets a wheel steering angle of the vehicle (100); a braking device (20), in particular a brake-by-wire braking device, comprising at least one individually controllable brake (22, 24), wherein each wheel steering angle actuator (12, 24) is assigned a brake (12, 24) that generates a braking effect (22a, 24a) assigned to the wheel steering angle actuator (12, 14); wherein the steering device (10) and the braking device (20) are configured to carry out the method (200) according to any one of claims 1 to 9.

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