Method for operating vehicle with defect in individual wheel steering adjuster and control device

Abstract

To provide a method for operating a vehicle (100) with a defect (106) in an individual wheel steering adjuster (102).SOLUTION: In the method, an avoidance direction (112) for steering intervention for avoiding a collision is determined depending on a speed of the vehicle (100) and a side of the defect (106).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for operating a vehicle with defects in the individual wheel steering regulators, a corresponding control device and a corresponding computer program product. [Background technology]

[0002] The vehicle may have an emergency brake assistance system that is able to initiate emergency braking of the vehicle by automated braking intervention if the vehicle gets too close to an obstacle and is at risk of a collision, for example if the driver of the vehicle fails to see the tail of a traffic jam, which may cause a collision with at least one vehicle at the tail of the traffic jam.

[0003] The enhanced emergency braking assistance system may also initiate evasive maneuvers by automated steering intervention to steer the vehicle sideways around an obstacle to avoid an otherwise unavoidable collision or to mitigate the need for heavy braking. For example, the enhanced emergency braking assistance system may steer the vehicle into an open lane adjacent to the tail end of a traffic jam, thereby avoiding a collision. Summary of the Invention [Problem to be solved by the invention]

[0004] Disclosure of the Invention Against this background, a method for operating a vehicle with defects in the individual wheel steering regulators using the approach presented herein, a corresponding control device and a corresponding computer program product are presented according to the independent claims. Preferred developments and improvements of the approach presented herein are evident from the description and are also set out in the dependent claims. [Means for solving the problem]

[0005] Advantages of the invention A two-track vehicle typically has two steerable wheels on the same axle, each of which is typically assigned a specific individual wheel steering regulator. Accordingly, a vehicle generally has two controllably actuable individual wheel steering regulators that are operated independently of one another.

[0006] If a defect exists in a vehicle's individual wheel steering adjuster, the vehicle's steering capabilities may be limited. For example, the vehicle may not be able to steer more in one direction than in the other. This may result in the vehicle no longer being able to take unlimited evasive action to avoid a collision.

[0007] The approach presented herein takes advantage of the fact that depending on how fast the vehicle is traveling, it may be more appropriate to steer the vehicle towards the side with the defect or away from the defect. Therefore, in the approach presented herein, defects are registered and taken into account along with the vehicle's speed when planning a trajectory for the vehicle.

[0008] The approach presented here allows for predefining an avoidance direction that is compatible with the current speed, thereby avoiding situations where the planned avoidance trajectory cannot be achieved. As the speed changes, the avoidance direction may also change.

[0009] Here, a method is presented for operating a vehicle with a defect in an individual wheel steering adjuster, in which the avoidance direction for steering intervention to avoid a collision is determined depending on the speed and / or lateral acceleration of the vehicle and the side of the defect.

[0010] The ideas for the embodiments of the present invention can be considered to be based, inter alia, on the considerations and knowledge set forth below.

[0011] A vehicle with individual wheel steering adjusters can have a right individual wheel steering adjuster and a left individual wheel steering adjuster at the steering axle. A vehicle can also have individual wheel steering adjusters at multiple axles. Each individual wheel steering adjuster acts on a specific steerable wheel of the vehicle. The individual wheel steering adjusters or the wheels of the steered axles are not mechanically connected to each other in terms of steering or to the steering wheel of the vehicle. The individual wheel steering adjusters are controlled via a data signal from a central transmitter at the steering wheel or steering lever of the vehicle.

[0012] If one individual wheel steering regulator is defective, the other individual wheel steering regulator generally does not. If defective, the individual wheel steering regulator may be completely non-functional or may have limited functionality. If the individual wheel steering regulator is completely non-functional, it may not apply steering torque to the wheel or may only apply minimal steering torque. A defective individual wheel steering regulator may also apply a small blocking torque to the wheel. If the individual wheel steering regulator has limited functionality, it may, for example, apply a reduced steering torque to the wheel and / or provide a reduced adjustment speed.

[0013] If one individual wheel steering adjuster is defective, essentially only the wheel connected to the other individual wheel steering adjuster can still be actively steered. When the vehicle starts moving and the wheel with the defective individual wheel steering adjuster moves freely or only a small torque acts on it, the wheel with the defective individual wheel steering adjuster can self-align via its own caster, i.e., can substantially adapt its angle to the direction of vehicle movement. If an external torque, such as a driving torque or braking torque, on the wheel with the defective individual wheel steering adjuster exceeds the self-aligning torque and / or blocking torque of the defective individual wheel steering adjuster, or if the aligning force is too low, and an excessively large steering angle is set via the intact adjuster, the wheel may turn inward, which may cause its angle to deviate from the direction of vehicle movement, i.e., be aligned obliquely or laterally relative to the direction of movement.

[0014] When the vehicle is traveling and the wheels connected to the functioning individual wheel steering regulators are steered, a narrow steering radius for avoiding a collision, for example, for avoiding an obstacle ahead, can be determined depending on the vehicle speed, favoring steering toward the defective individual wheel steering regulator or steering toward the functioning individual wheel steering regulator. That is, the avoidance direction can be selected depending on the speed. This avoidance direction can also be continuously determined depending on the speed as a preferred avoidance direction, even if no situation requiring the vehicle to avoid an obstacle occurs. The avoidance direction can be stored in a memory, for example, and can be read out when an avoidance maneuver is required. The stored avoidance direction can be changed depending on the speed.

[0015] The avoidance direction can further depend on the distance to the collision object. The collision object can be, for example, a stationary or slow-moving vehicle in one lane or on the track of the vehicle. The collision object can also be, for example, a vehicle at the end of a traffic jam ahead of the vehicle. The vehicle can also be a vehicle that suddenly reduces its speed, for example, due to an unexpected need to brake suddenly or being involved in an accident. The distance to the collision object determines the radius of curvature required for successful avoidance. The smaller this distance, the smaller or narrower the radius of curvature during avoidance may be. The collision object can also be a potential collision object, i.e., a vehicle traveling ahead. In this case, the avoidance direction can be stored in a memory for the avoidance case.

[0016] The avoidance direction can be determined when moving away from the fault side at a speed lower than a threshold value. Alternatively or additionally, the avoidance direction can be determined when moving away from the fault side at a distance greater than a distance value. "Fault side" or "side of the faulty individual wheel steering regulator" is understood here to mean the side of the vehicle on which the faulty individual wheel steering regulator is located. At low speeds and large radii of curvature, i.e. when dynamic avoidance maneuvers are slight, the wheels of the vehicle on the inside of the curve are the lane-determining side, i.e. they determine in which direction the vehicle will travel. The wheels on the outside of the curve can now follow with their own caster. If the distance is long enough, avoidance can be achieved with a large radii of curvature. Above the threshold value and / or below the distance value, e.g. 4 m / s 2 The lateral acceleration can exceed that of

[0017] The avoidance direction can be determined when the vehicle moves toward the defect at a speed higher than the threshold value. Alternatively or additionally, the avoidance direction can be determined when the vehicle moves toward the defect at a distance smaller than the distance value. When the speed is high and the radius of curvature is small, i.e., in the case of a relatively large dynamic avoidance maneuver, the vehicle rolls at the start of the movement, and the wheels on the outside of the curve of the vehicle are loaded more, while the wheels on the inside of the curve are unloaded. This allows the wheels on the outside of the curve to transmit more side force than the wheels on the inside of the curve as a basis. In other words, the wheels on the outside of the curve of the vehicle are the lane-determining side during a relatively large dynamic avoidance maneuver and determine which direction the vehicle will travel.

[0018] A steering intervention can be evaluated as inappropriate if the required avoidance space in the preferred avoidance direction is occupied. The avoidance space for the avoidance maneuver can be located to the right or left of the collision object. The avoidance space can be located, in particular, in a lane or a siding located to the right or left of the collision object. A sensor system of the vehicle can monitor the surroundings of the vehicle. This sensor system can monitor the avoidance space here. If another vehicle or another obstacle is identified in the avoidance space, the vehicle will cause an alternative collision when avoiding into the avoidance space in front of the collision object. If another vehicle or another obstacle is identified in the avoidance space, this avoidance space can be identified as occupied. An alternative collision can thereby be prevented. Monitoring of the avoidance space can be performed continuously, and the avoidance space can be stored in a memory as currently occupied or currently vacant, respectively.

[0019] Furthermore, an intervention distance for braking intervention to avoid a collision can be set depending on the speed, the available avoidance space, and the side of the defect. The intervention distance can be the distance to the collision object, from which an automated braking intervention to avoid a collision is initiated. The intervention distance can be extended if a defect is identified. The intervention distance can be extended with an increase in speed. If the avoidance space is identified as occupied, the intervention distance can be further extended to prevent or at least mitigate a collision even without avoidance.

[0020] The method is preferably computer-implemented, and may for example be implemented in software or hardware, or in a mixed form of software and hardware, for example in a driver assistance system.

[0021] The approach presented herein further provides a control device, wherein the control device is configured to perform, drive or execute the steps of the method variants presented herein in a corresponding device.

[0022] The control device may be an electrical device comprising at least one computing unit for processing signals or data, at least one memory unit for storing signals or data, and at least one interface and / or communication interface for reading or outputting data embedded in a communication protocol. The computing unit may be, for example, a signal processor, a so-called system ASIC, or a microcontroller for processing sensor signals and outputting data signals depending on the sensor signals. The memory unit may be, for example, a flash memory, an EPROM, or a magnetic memory unit. The interface may be configured as a sensor interface for reading sensor signals from sensors and / or as an actuator interface for outputting data and / or control signals to actuators. The communication interface may be configured for reading or outputting data wirelessly and / or via a wired connection. The interface may be, for example, a software module residing on a microcontroller adjacent to other software modules.

[0023] Also advantageous is a computer program product or computer program having a program code, which may be stored on a machine-readable carrier or storage medium, such as a semiconductor memory, a hard disk memory or an optical memory, and which is in particular used for implementing, executing and / or driving control the steps of the method according to one of the above-described embodiments when the computer program product or computer program is run on a computer, in a control device or in an apparatus.

[0024] It should be noted that some of the possible features and advantages of the present invention are described herein with reference to different embodiments, and those skilled in the art will recognize that the features of the control devices and methods can be mixed, matched, or exchanged as appropriate to arrive at further embodiments of the present invention.

[0025] In the following, embodiments of the present invention will be described with reference to the accompanying drawings, whereby neither the drawings nor the description should be construed as limiting the present invention. [Brief explanation of the drawings]

[0026] [Figure 1] 1 illustrates vehicles with faulty individual wheel steering regulators and different speeds when implementing an evasive maneuver using the method according to one embodiment. [Figure 2] 1 illustrates vehicles with faulty individual wheel steering regulators and different speeds when implementing an evasive maneuver using the method according to one embodiment.

[0027] The drawings are merely schematic and are not to scale. Identical reference symbols indicate identical or equivalently acting features. DETAILED DESCRIPTION OF THE INVENTION

[0028] Embodiments of the invention FIG. 1 shows a depiction of a vehicle 100 with a faulty individual wheel steering modulator 102 and low speed when performing an evasive maneuver using a method according to one embodiment.

[0029] FIG. 2 shows a depiction of a vehicle 100 with a faulty individual wheel steering modulator 102 and high speed when performing an evasive maneuver using a method according to one embodiment.

[0030] In both figures, the vehicle 100 has front wheels 104 that are steered via one individual wheel steering adjuster 102. In the illustrated example, the left individual wheel steering adjuster 102 has a fault 106. The right individual wheel steering adjuster 102 has unlimited functionality. The faulty individual wheel steering adjuster 102 is now unable to apply a steering torque to the left front wheel 104. This fault 106 could alternatively cause the individual wheel steering adjuster to only provide a reduced steering torque. Here, the faulty individual wheel steering adjuster 102 can only apply a small holding torque to the left front wheel 104. Therefore, when the vehicle 100 starts to move, the left front wheel 104 can adapt its steering angle via its caster to the direction of movement of the vehicle 100 if the torque generated by the caster is greater than the holding torque and the external torque generated by braking or driving the front wheel 104.

[0031] In both figures, a vehicle 100 is traveling towards a collision object 108 or obstacle. The collision object 108 is here, for example, a stationary truck. If the vehicle 100 is not braked and / or avoided, a collision with the collision object 108 will occur. The available braking distance to the collision object 108 may already be so small that a collision may occur despite emergency braking intervention. By avoiding into an avoidance space 110 adjacent to the collision object 108, the collision can be prevented and emergency braking intervention can be performed with a reduced braking torque, because an extended braking distance is provided by the avoidance space 110.

[0032] 1, the vehicle 100 is traveling at a low speed. This low speed results in a slight dynamic avoidance maneuver in which the weight of the vehicle 100 is only slightly shifted to the vehicle's outside wheel. Therefore, the front wheel 104 on the inside of the curve at low speed is the lane-determining side.

[0033] 2, the vehicle 100 is traveling at a high speed. This high speed results in a dynamic avoidance maneuver that shifts most of the weight of the vehicle 100 to the outside front wheel 104 of the curve, unloading the inside front wheel 104. Therefore, the high speed outside front wheel 104 of the curve is the lane-determining side.

[0034] Since the speed determines which side is the lane-determining side, in the approach presented herein, the side of the fault 106 and the speed are used to determine the avoidance direction 112 for the avoidance maneuver. In this case, the avoidance direction 112 is determined such that the individual wheel steering coordinator 102 with functionality is the lane-determining side, and the individual wheel steering coordinator 102 with the fault 106 is not the lane-determining side. The avoidance direction 112 can be determined continuously here and can be called up if a risk of collision is identified. Therefore, the duration of the decision can be saved.

[0035] In one embodiment, for speeds below the threshold, the wheel on the inside of the curve is assumed to be the lane determining side, and for speeds above the threshold, the wheel on the outside of the curve is assumed to be the lane determining side. Correspondingly, the avoidance direction 112 is determined to be away from the defect 106 for speeds below the threshold and towards the defect 106 for speeds above the threshold.

[0036] In one embodiment, the avoidance direction 112 is further determined using the distance to the collision object 108. If a risk of collision is identified, the closer the vehicle 100 is to the collision object 108, the more dynamic the avoidance maneuver must be to be successful. Here, for example, the speed threshold may be reduced as the distance decreases.

[0037] In one embodiment, the avoidance direction 112 is determined only if the avoidance space 110 is free in this avoidance direction 112. If the avoidance space 110 in the avoidance direction 112 is occupied, the avoidance direction 112 is not stored and emergency braking is performed without avoidance if there is a risk of collision.

[0038] In one embodiment, the intervention distance for the avoidance maneuver is set depending on the side of the defect 106, the speed, and the available avoidance space 110. That is, for example, if the avoidance space 110 is only available on the opposite side of the defect 106, a dynamic avoidance maneuver to the side of the defect 106 is not possible. In other words, to still be able to perform an avoidance maneuver, a slight dynamic avoidance maneuver away from the side of the defect 106 is required. This slight dynamic avoidance maneuver can only be performed with an extended distance to the collision object 108, i.e., if the intervention distance is extended. When the avoidance space 110 on the side of the defect 106 becomes available again, the intervention distance can be reduced again.

[0039] In the following, possible embodiments of the invention are summarized again or presented with slightly different wording.

[0040] Here, an operating strategy is presented for speed-dependent actuation control of individual wheel steering regulators in the event of a steering regulator failure or degradation.

[0041] Today's vehicles are equipped with electromechanical steering connected to both wheels. Development of steering systems is increasingly moving in the direction of by-wire systems, which are mechanically decoupled from the driver. Here, the classic mechanical connection between the driver and the wheels themselves via the steering wheel is omitted. In the case of steering, the corresponding operation is carried out purely via one or more regulators. Centralized as well as decentralized by-wire steering regulators are already installed on the rear axle. For the front axle, the first prototype vehicles with by-wire individual wheel steering regulators are known, such as the research vehicle SpeedE.

[0042] The driver assistance automatic collision avoidance system (ACA) can assist in dangerous situations, such as when the driver recognizes the end of a traffic jam too late. In contrast to conventional emergency braking functions, this system can automatically steer the vehicle into an open lane if there is not enough space for emergency braking in the current lane. If the distance to the end of the traffic jam is large enough, the assistance system will stop the car using conventional emergency braking. Automated collision avoidance supports the driver on highways up to speeds of 130 km / h.

[0043] In the future, NCAP testing will include requirements for automated avoidance.

[0044] So far, there is no optimal drive control strategy for individual wheel steering regulators for avoidance in the event of regulator failure. A strategy for handling drive and braking in the event of a defective individual wheel steering regulator can take into account the partially reduced braking capacity on the part of the defective steering regulator, which makes avoidance even more relevant, since the braking capacity is reduced to avoid the wheels turning in / out due to the defective regulator.

[0045] The approach presented here takes advantage of the fact that different optimal drive controls for the remaining individual wheel steering regulators occur depending on the speed or lateral acceleration and the associated variations in wheel load.

[0046] Lateral acceleration is 4m / s 2 In slightly dynamic driving below 100°, the inside wheel takes the lane lead when cornering due to the steering geometry designed near Ackermann, i.e. is decisive for the driving trajectory.

[0047] At correspondingly high speeds or narrow curvature radii, the wheel on the outside of the curve will have lane dominance due to dynamic wheel load displacement (rolling).

[0048] This obviously means that, for example, when approaching the tail of a traffic jam, swerving to one side (left or right of the tail of the traffic jam) will result in a collision depending on the faulty regulator side, and not on the other side. Furthermore, this would leave more distance for the initiation of further measures, for example based on a narrower radius of curvature.

[0049] With the approach presented here, this information can be provided to the emergency brake assistance so that it knows from when only full braking is still possible and to which side avoidance is still possible. These measures can be used to determine the remaining duration when approaching an obstacle, which is input to the emergency brake assistance system.

[0050] If the distance is sufficient, avoidance and braking are possible in both directions.

[0051] If the distance is too small, avoidance and braking are still possible only on one side, the side of the faulty steering regulator being taken into account here.

[0052] If only emergency braking is still possible, the operational strategies presented herein improve survivability in the event of a system failure, and thus increase safety.

[0053] If replaced by an individual wheel steering regulator, this means that, for example, when approaching a stationary obstacle, if the left steering regulator fails in the region of low speed or lateral acceleration, it is advantageous to avoid to the right based on a purely kinematic steering effect without wheel load displacement, because the remaining right wheel can steer more strongly on the inside of the curve. At high speed or lateral acceleration, avoiding to the left side is advantageous in terms of the achievable curvature radius, because the wheel on the outside of the curve has an advantage in terms of lane guidance.

[0054] Furthermore, the functions presented herein can incorporate information from environmental sensors to identify corresponding acceptable avoidance trajectories and determine the minimum necessary but maximum possible dynamics. If the ideal avoidance direction is unlikely to be acceptable based on, for example, traffic ahead or traffic following behind, a less preferred direction can be selected, or avoidance can be omitted in favor of braking with maximum deceleration. Alternatively, measures such as braking can be initiated correspondingly earlier.

[0055] For example, if the left adjuster fails passively, at low speeds / lateral accelerations the avoidance will be to the right, and at high speeds / lateral accelerations the avoidance will be to the left.

[0056] The operating strategy presented here is also applicable to degraded individual wheel steering regulators when it appears that they are no longer sufficient to dynamically bring about the target steering angle, i.e., for example, when 50% steering torque remains.

[0057] Additionally, the operating strategies presented herein can also be applied to steer-by-wire and EPS centralized regulators.

[0058] Finally, it should be noted that words such as "comprise" and "include" do not exclude other elements or steps, and words such as "a" and "an" do not exclude a plurality. Reference signs in the claims are not to be construed as limiting.

Claims

1. A method for operating a vehicle (100) with a defect (106) in an individual wheel steering regulator (102), comprising: A method, wherein an avoidance direction (112) for steering intervention to avoid a collision is determined depending on the speed of the vehicle (100) and the side of the defect (106).

2. The method of claim 1 , wherein the avoidance direction (112) is further determined depending on a distance to a collision object (108).

3. The method of claim 1 or 2, wherein the avoidance direction (112) is determined in case of a speed less than a threshold value and / or a distance greater than a distance value away from a side of the defect (106).

4. 4. The method according to claim 1, wherein the avoidance direction (112) is determined in case of a speed greater than a threshold value and / or a distance less than a distance value towards the side of the defect (106).

5. 5. The method according to claim 1, wherein the steering intervention is evaluated as inappropriate if the required avoidance space (110) in the preferred avoidance direction (112) is occupied.

6. 6. The method according to claim 1, further comprising setting an intervention distance for a braking intervention to avoid a collision depending on the speed, the available avoidance space (110) and the side of the defect (106).

7. The method according to claims 5 and 6, wherein the intervention distance is increased if the avoidance space (110) is occupied.

8. A control device adapted to implement, execute and / or drive a method according to any one of claims 1 to 7 in a corresponding device.

9. 8. A computer program product configured to cause a processor to perform, execute and / or drive a method according to any one of claims 1 to 7, when the computer program product is executed.

10. 10. A machine-readable storage medium having stored thereon the computer program product of claim 9.

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