Method and controller for shunting vehicles with defects in the single-wheel steering adjuster of the drive wheels.

Abstract

The present invention relates to a method for shunting a vehicle (100) having a defect (106) at a single-wheel steering adjuster (102) of a driven wheel (104) of the vehicle (100), wherein the torque at the wheel (104) is set according to the steering angle of the opposite wheel (104) of the vehicle (100) for shunting.

Description

Technical Field

[0001] The present invention relates to a method for adjusting a vehicle with a defect in the single-wheel steering adjuster of the driven wheel, a corresponding controller, and a corresponding computer program product. Background Technology

[0002] The vehicle can have an electromechanical steering system. Here, the driver's steering force is transmitted from the steering wheel to the steering wheels via a mechanical connection. The steering force is detected and supported by an electrically adjustable drive mechanism. Even when the adjustable drive mechanism malfunctions, the driver can still steer the wheels despite increased resistance.

[0003] In vehicles equipped with a single-wheel steering adjuster, the mechanical connection between the steering wheel and the steering wheels is eliminated. The steering force is converted into an electrical signal at the steering wheel, and the single-wheel steering adjuster is controlled by the signal.

[0004] When a single-wheel steering adjuster is defective, the affected wheel can no longer be steered as intended. This defect can be complete failure or merely a functional limitation.

[0005] When a single-wheel steering adjuster completely fails, it can be configured so that it does not apply any adjusting force to the wheel, and if it does, only a small holding force. Thus, the wheel can self-align via its kingpin caster during driving and maintain emergency operating capability. However, self-alignment achieved via kingpin caster only functions while the vehicle is in motion. Summary of the Invention

[0006] Against this backdrop, the present invention provides, according to the independent claim, a method for rangieren (adjusting) a vehicle with a defect at the single-wheel steering adjuster of the driven wheels, a corresponding controller, and a corresponding computer program product. Advantageous modifications and improvements to the present invention are derived from the specification and described in the dependent claims.

[0007] When a vehicle with a defective single-wheel steering adjuster starts moving from a standstill, the self-alignment of the wheel steered by the defective single-wheel steering adjuster only becomes effective above a certain speed. Below this speed, the angular position of the wheel is largely affected by the torque applied to the wheel, for example, through the drive unit or brakes.

[0008] The proposed scheme here influences the torque applied to the wheel to prevent undesirable angular position changes and / or to induce or facilitate desired angular changes.

[0009] The proposed solution enables a vehicle to start moving from a standstill despite the defect in the single-wheel steering adjuster, without causing the wheel with the defective single-wheel steering adjuster to twist laterally in the desired direction of travel and thus prevent it from moving.

[0010] A method is proposed for adjusting a vehicle with defects in the single-wheel steering adjuster of the driven wheel of the vehicle, wherein the torque at the wheel is set according to the steering angle of the opposite wheel of the vehicle or according to the steering wheel angle for adjusting the vehicle.

[0011] The conception of embodiments of the present invention can be particularly regarded as being based on the ideas and understandings described below.

[0012] Vehicles equipped with single-wheel steering adjusters can have a right-side single-wheel steering adjuster and a left-side single-wheel steering adjuster at the steering axle. Vehicles can also have single-wheel steering adjusters on multiple axles. Here, each single-wheel steering adjuster acts on the vehicle's own steerable wheel. The wheels of the single-wheel steering adjuster or steering axle are not mechanically coupled to each other or to the vehicle's steering wheel. The single-wheel steering adjuster is controlled by a central sensor located at the vehicle's steering wheel or steering arm via data signals.

[0013] When one of the single-wheel steering adjusters is defective, the other single-wheel steering adjuster is unaffected. In the case of a defect, the single-wheel steering adjuster may be completely unusable or only partially functional. When a single-wheel steering adjuster is completely unusable, it cannot apply steering torque to the wheel or it applies only minimal steering torque to the wheel. A defective single-wheel steering adjuster may also apply low resistive torque to the wheel. When a single-wheel steering adjuster is partially functional, it may, for example, apply reduced steering torque to the wheel and / or apply a reduced adjustment speed.

[0014] When one of the single-wheel steering adjusters is defective, essentially only the wheel coupled to the other, intact single-wheel steering adjuster on the steering axle can still be fully steered. When the vehicle moves and the wheel with the defective single-wheel steering adjuster moves freely or only a small torque acts on it, the wheel with the defective single-wheel steering adjuster can self-center via its kingpin caster, thus its angle is essentially adapted to the vehicle's direction of motion. When external torques, such as driving or braking torques, at the wheel with the defective single-wheel steering adjuster exceed the self-centering torque and / or resisting torque of the defective single-wheel steering adjuster, the wheel will wobble inward, and its angle will thus deviate from the vehicle's direction of motion, i.e., tilted or lateral relative to that direction of motion.

[0015] During shunting, the vehicle is stationary, starts moving from a standstill, and travels at very low speeds. Therefore, wheel self-alignment achieved through kingpin caster is either only partially effective or completely ineffective. During shunting, the vehicle travels, for example, within a speed range of 0 km / h to 7 km / h.

[0016] If a torque causes a wheel to turn in the opposite direction to the steering angle at the other wheel and thus impedes the direction of the vehicle's movement, then the torque can be suppressed, delayed, and / or at least weakened.

[0017] Furthermore, the torque can be set based on the current angular position of the wheel. If the current angular position of the wheel substantially corresponds to the steering angle of the other wheel, then, for example, only a portion of the torque normally used can be applied so as not to significantly change the angular position of the wheel. However, if the angular position deviates significantly from the steering angle, a forward or reverse-direction torque can be applied to actively bring the angular position of the wheel at least close to the steering angle. The torque used for wheel orientation can be applied before the driving torque is applied to the opposing wheel, thus ensuring that the wheel is at least nearly oriented before the vehicle begins to move. When the vehicle begins to move, the wheel can achieve self-centering through its caster.

[0018] Furthermore, the torque can be set based on the driving torque at the opposite wheel. The applied torque can be set to be less than the driving torque. Only a portion of the driving torque can be set at the wheel. This prevents the inward sway. The torque can also be set in the opposite direction to the driving torque, thereby allowing the slightly inward-swaying wheel to swerve outward. When the wheel is swerved outward, only a portion of the driving torque can be set again in the direction of the driving torque.

[0019] The torque can be set to be a factor lower than the initially set driving torque. For example, the torque can be set to 1 / 3 or 1 / 4 of the driving torque.

[0020] The torque can be set in a way that is time-displaced relative to the driving torque at the opposite wheel. First, a driving torque can be applied to move the vehicle. Thus, the wheel with the defective single-wheel steering adjuster can be oriented in the steering direction of a normally operating wheel. Then, the torque can be set. Here, a reduced torque can also be set.

[0021] It can reduce the torque gradient. It can also reduce the driving torque gradient. By reducing the gradient, shocks at the wheels and wheel sway can be avoided. Alternatively, the torque gradient can be set to be less than the driving torque gradient. As a result, the torque can rise more slowly than the driving torque. This allows the wheels time to self-align.

[0022] The torque can be set according to the vehicle's speed. The slower the vehicle moves, the smaller the torque can be set. The self-aligning effect of the wheels becomes stronger as speed increases. As a result, increasingly larger torques can be transmitted without causing the wheels to wobble inward.

[0023] The method is preferably implemented by a computer and can be implemented, for example, in software or hardware or in a hybrid form of software and hardware, such as in a driver assistance system.

[0024] Furthermore, the proposed solution provides a controller, wherein the controller is configured to perform, manipulate, or implement a variation of the proposed method in a corresponding device.

[0025] The controller can be an electrical device having at least one computing unit for processing signals or data, at least one storage unit for storing signals or data, and at least one interface and / or communication interface for reading in or outputting data embedded in a communication protocol. The computing unit can be, for example, a signal processor, a so-called system ASIC, or a microcontroller for processing sensor signals and outputting data signals based on the sensor signals. The storage unit can be, for example, flash memory, EPROM, or magnetic storage. The interface can be configured as a sensor interface for reading sensor signals from a sensor, and / or an actuator interface for outputting data signals and / or control signals to an actuator. The communication interface can be configured for wirelessly and / or wiredly reading in or outputting data. The interface can also be a software module, which may coexist with other software modules on the microcontroller, for example.

[0026] It is also advantageous to have a computer program product or a computer program having program code that can be stored on a machine-readable carrier or storage medium such as semiconductor memory, hard disk memory or optical memory, and especially when the program product or program is executed on a computer, controller or device, it is used to perform, implement and / or manipulate the steps of the method according to one of the above embodiments.

[0027] It should be noted that these possible features and advantages of the present invention are described herein with reference to different embodiments. Those skilled in the art will recognize that the features of the controller and the features of the method can be combined, adjusted, or exchanged in a suitable manner to obtain other embodiments of the invention. Attached Figure Description

[0028] The embodiments of the present invention will now be described with reference to the accompanying drawings, which should not be construed as limiting the invention.

[0029] Figure 1 An illustration shows a vehicle with a defective single-wheel steering adjuster being adjusted using a method according to one embodiment; and Figure 2 A diagram illustrating the steering angle variation curve and torque variation curve according to a method according to one embodiment is shown.

[0030] The accompanying drawings are schematic only and are not to scale. The same reference numerals denote the same or equivalent features. Detailed Implementation

[0031] Figure 1 A diagram is shown illustrating a vehicle 100 with a defective single-wheel steering adjuster 102 during styling according to one embodiment. The vehicle 100 has a front-wheel drive system. The front wheels 104 of the vehicle 100 are thus capable of steering and are coupled to the vehicle 100's drive system. The drive system is configured to provide individually set torques on the two front wheels 104. Here, the torque at the front wheel 104 with the defective single-wheel steering adjuster 102 is referred to as torque. The torque at the front wheel 104 with a properly functioning single-wheel steering adjuster 102 is referred to as driving torque.

[0032] Here, for example, the left-side single-wheel steering adjuster 102 has a defect 106. The right-side single-wheel steering adjuster 102 functions perfectly. The defective single-wheel steering adjuster 102 cannot apply steering torque to the left front wheel 104. Due to the defect 106, the single-wheel steering adjuster 102 can only provide a reduced steering torque instead. Here, the defective single-wheel steering adjuster 102 only applies a low holding torque to the left front wheel 104. Therefore, when the vehicle 100 rolls, if the torque generated by the kingpin caster is greater than the holding torque and greater than the external torque generated by braking or driving the front wheel 104, the left front wheel 104 can adapt its steering angle to the direction of movement of the vehicle 100 through its kingpin caster.

[0033] Here, vehicle 100 is, for example, in a parking space between two obstacles 108 (e.g., other parked vehicles) parallel to the right-hand curb 110. In order to leave the parking space, vehicle 100 must begin to move and turn at a large steering angle. Since the distance to the obstacle 108 in front is greater than the distance to the obstacle 108 behind, it is necessary to begin moving forward and turning to the left.

[0034] By applying torque to the wheel being steered, an external torque is generated through the steering kingpin offset (Lenkroll radius) and / or interference arm, which causes the wheel to swerve inward about the wheel steering axis.

[0035] At the right front wheel 104 of vehicle 100, a properly functioning right-side single-wheel steering adjuster 102 supports the external torque and thus prevents uncontrolled leftward swerving. The right-side single-wheel steering adjuster 102 applies a steering torque to turn the right front wheel 102 to the left. At the right front wheel 104, the external torque and the steering torque thus complement each other. This only applies here because inward steering occurs.

[0036] At the left front wheel 104, the defective left-side single-wheel steering adjuster 102 can only support the external torque with the remaining holding torque. If the external torque is greater than the holding torque, the left front wheel 104 will swing inward to the right and thus laterally to the desired direction of travel.

[0037] In the proposed solution, the torque at the front wheel 104 with the defective single-wheel steering adjuster 102 is controlled according to the desired driving direction of the vehicle 100 to prevent inward sway.

[0038] In one embodiment, the torque is set based on the driving torque set at the right front wheel 104. Here, this torque is set to be smaller than the driving torque. For example, the torque is set to be smaller than the driving torque by a scaling factor. With the reduced torque, the tendency of the left front wheel 104 to wobble inward is also reduced.

[0039] In one embodiment, the torque at the left front wheel 104 is applied more slowly than the driving torque at the right front wheel 104. By applying it slowly, the torque rises less per unit of time than the driving torque. In other words, the gradient or slope of the torque is reduced relative to the driving torque. This slower rise reduces the tendency of the left front wheel 104 to wobble inwards.

[0040] In one embodiment, torque is applied to the left front wheel 104 with a time delay. Here, a driving torque is first applied to the right front wheel 104, and then torque is applied to the left front wheel 104 with a time delay. Due to the time delay, the left front wheel 104 begins to roll without torque and can freely orient itself, or stabilize. The torque is applied after the left front wheel 104 has oriented or stabilized.

[0041] In one embodiment, torque is applied according to the vehicle's speed. Here, a lower torque is applied at low speeds and a higher torque is applied at higher speeds. Due to the speed, the wheel is self-stabilized by its kingpin caster and can withstand external torques caused by the torque generated by the kingpin caster.

[0042] Figure 2The diagram illustrates the steering angle variation curve 200, angular position variation curve 202, driving torque variation curve 204, torque variation curve 206, and speed variation curve 208 when a vehicle is maneuvered according to one embodiment. Here, the vehicle essentially corresponds to... Figure 1 The vehicle is shown in the diagram. Steering angle variation curve 200 shows the time-varying steering angle of the right front wheel. The right front wheel is steered by a functional single-wheel steering adjuster. Angle position variation curve 202 shows the time-varying angle position of the left front wheel. The left front wheel is coupled to a defective single-wheel steering adjuster. Steering angle variation curve 200 and angle position variation curve 202 can be referred to as track angle variation curves. Driving torque variation curve 204 shows the time-varying driving torque at the right front wheel. Torque variation curve 206 shows the time-varying torque at the left front wheel. Speed ​​variation curve 208 shows the time-varying speed of the vehicle.

[0043] These variation curves are shown in a graph, which plots time on its horizontal axis and angular position, steering angle, driving torque, torque, and speed on its vertical axis.

[0044] Initially, the steering angle and angular position are equal to zero degrees (0°). The two front wheels are therefore oriented along the longitudinal direction of the vehicle. To maneuver out of the parking space, turn left. Here, due to a defect in the single-wheel steering adjuster on the left, only the steering angle of the right front wheel changes. The angular position of the left front wheel remains unchanged at zero degrees.

[0045] Then, apply driving torque or torque to the two front wheels. Apply torque according to the steering angle.

[0046] In one embodiment, a lower driving torque is applied to the left front wheel with a defective single-wheel steering adjuster than to the right front wheel.

[0047] In one embodiment, one-third of the total torque is applied to the left front wheel and two-thirds of the total torque is applied to the right front wheel.

[0048] In one embodiment, torque is applied at a gradient lower than the driving torque.

[0049] In one embodiment not shown, the torque is applied in a manner that offsets the time following the driving torque.

[0050] By applying torque and driving torque differentially, the vehicle begins to move and its speed increases. During the initial movement, the angular position of the left front wheel changes to the left, and at this point even briefly exceeds the target steering angle based on the steering angle of the reference wheel.

[0051] After the angle of the left front wheel has been matched with the steering angle of the right front wheel, the vehicle moves out of the parking space, and the right front wheel turns to the right. As the moving speed increases, the self-centering of the left front wheel begins, and the angle of the left front wheel follows the right steering angle of the right front wheel with a slight delay.

[0052] Subsequently, the right front wheel aligns again. The left front wheel follows the alignment movement again with a slight delay. After both front wheels are once again essentially oriented along the vehicle's longitudinal direction, torque and drive torque are reduced, and the vehicle comes to a stop. Thus, despite the defect in the left-side single-wheel steering adjuster, the slewing was still performed and is now complete.

[0053] Next, the possible design schemes of the present invention will be summarized again or presented in slightly different terms.

[0054] An operational strategy for distributing drive torque during the parking process in the event of a defect in the single-wheel steering adjuster is proposed.

[0055] Modern vehicles are equipped with electromechanical steering systems connected to both wheels. The development of steering systems is increasingly trending towards steer-by-wire systems that are mechanically decoupled from the driver, eliminating the traditional mechanical connection between the driver and the wheels via the steering wheel. In the event of steering, the corresponding actuation is achieved purely through one or more adjusters. A central steer-by-wire adjuster is installed at the rear axle, but distributed steer-by-wire adjusters (ZF: AKC) are also used. At the front axle, the first prototype vehicles (such as the SpeedE development vehicle) use steer-by-wire single-wheel adjusters.

[0056] Active torque transfer at the non-steering axle can support or influence the vehicle's cornering characteristics. It has been shown that, in the case of a fault, the free-moving nature of the single-wheel steering adjuster is advantageous. Here, torque transfer is adapted for fault conditions in a single-wheel steering adjuster at the driven wheel.

[0057] The proposed solution here addresses single-wheel steering adjusters in the event of steering adjuster failure, providing an optimized handling strategy for parking. Specifically, vehicles with front-wheel drive present challenges due to the kinematic relationship between drive torque and the resulting steering torque. In the case of single-wheel steering adjuster failure, special handling of the drive unit and brakes is required because the axle's centering effect, particularly due to kingpin inclination, is speed-dependent. At low speeds, such as when parking, this centering effect is insufficient to stabilize the wheels. This, along with other effects, can lead to passive failure of the single-wheel steering adjuster, causing inward sway.

[0058] With the steering adjuster functioning correctly, the adjustment prevents movement caused by the driving torque, or rather, adjusts the vehicle to the target position. Therefore, a core element of the proposed solution is to prevent the wheels from unfavorably turning inward about the vertical axis due to steering kingpin offset and driving torque. When the drive unit and / or brakes are not properly controlled, the combination of steering kingpin offset and driving torque can lead to undesirable wheel movement or even wheel wegklappen when the adjuster fails, hindering further vehicle maneuverability. Therefore, a control strategy for the drive unit is proposed that prevents this adverse performance condition when the vehicle is front-axle driven.

[0059] To enable starting from a parking space in the forward direction even with a single-wheel steering adjuster failure, different operating strategies are proposed. The following analysis exemplifies the failure of the adjuster on the inside of the left-hand curve.

[0060] Without further intervention, when starting with a steering wheel angle of 360° to 480° and adjusting the wheel steering angle accordingly only on the side of the intact adjuster, a lift of the front body occurs first, followed by inward sway of the defective steering adjuster. The driving torque in this situation promotes inward sway because it further enhances the inward rotation of the wheels about the vertical axis.

[0061] To counteract this situation, for example, it is possible to set a different drive torque distribution between the intact wheel and the defective wheel (right and left in this example). By reducing the drive torque on the defective adjuster side, the tendency to wobble can be reduced or completely avoided. On the intact side, unrestricted drive torque can continue to be applied or an increase in drive torque can be achieved, which compensates for the reduction in drive torque on the defective adjuster side.

[0062] Alternatively or additionally, the application of the driving torque can be extended until the target driving torque is reached, thus reducing the gradient of the driving torque accordingly. The impact of undesirable wheel rotation is mitigated by deceleration (first on both sides in this variant).

[0063] The gradient of the driving torque can also be reduced only on the defective side. On the intact regulator side, the gradient can be set as in normal operation.

[0064] These operating strategies can be applied in combination. That is, they can simultaneously redistribute the driving torque on both sides and adjust for changes in the driving torque over time.

[0065] Similarly, driving torque can be applied initially only on the intact adjuster side to initiate vehicle movement. Driving torque is then applied to the defective side only as the vehicle moves. Alternatively or additionally, the steering angle on the intact adjuster side can be applied directly or only when the vehicle is slightly moving, in order to utilize the kingpin caster effect on the defective side.

[0066] Additionally, the target steering angle is not applied directly to the normal adjuster at the normal ratio, but is instead achieved using a modified characteristic curve that operates with a smaller wheel steering angle when stationary and at low speeds (e.g., <5 km / h).

[0067] In another control strategy, the desired driving torque can be applied to the intact side. On the defective side, an adjuster is used to apply torque via the drive mechanism, causing the wheel to turn in the desired direction. This approach can be combined with driving the defective wheel as well, provided the appropriate steering angle allows.

[0068] In the proposed solution, a slight increase in maneuvering space is considered acceptable given the defective adjuster, as a serious fault already exists in the system and optimal handling performance cannot be expected. Without the proposed solution, the vehicle would no longer be able to steer.

[0069] Kinematic parameters such as steering kingpin offset and disturbance arm play a decisive role in wheel steering characteristics under conditions of adjuster failure. In particular, the braking torque and drag parameters can vary in magnitude and even sign depending on vehicle type and wheel condition. The proposed solution here can compensate for these effects.

[0070] Therefore, the operating strategy proposed here allows for good vehicle handling even in the event of a single-wheel steering adjuster failure. For electronic drive systems, with drive units installed at both the front and rear axles, the front-wheel drive can be shut off in the event of a single-wheel steering adjuster failure, allowing vehicle movement to be achieved solely through the rear axle drive.

[0071] exist Figure 2 The diagram shows the torque variation curves for the drive torque distribution. The drive torque is actually symmetrically distributed and adapted to the steering angle. Here, the actual required drive torque at the wheels ( The Chinese name is M 适配 It is derived in the following way: When driving backwards, ; Otherwise, when moving forward, ; otherwise, .

[0072] Here, These are variable parameters, which can be correlated, for example, with vehicle speed and axle kinematics. Furthermore, factors... The value is positive for the right front wheel and negative for the left front wheel, so that (in conjunction with "for left turns")... (The Chinese is a) 方向盘 The convention of ">0)" reduces the driving torque at the wheels on the inside of the curve. It is the required driving torque in a symmetrically distributed system. (Through proportional...) (The Chinese is a) 方向盘 / a 方向盘最大 This achieves the effect of not applying a large differential torque when the steering wheel angle and corresponding wheel steering angle are small. When the steering wheel angle is large, a correspondingly larger differential torque is required because a relatively large wheel steering angle is also needed in this case.

[0073] In principle, the operating strategy proposed here can also be applied to degraded single-wheel steering adjusters, such as those with 50% remaining steering torque, if this is no longer sufficient to counteract the driving force or excessively affect the adjuster's target position. When the steering kingpin offset is precisely designed so that the driving torque favors steering motion in the target direction, the driving torque distribution can also be adjusted accordingly.

[0074] Finally, it should be noted that terms such as "having" or "comprising" do not exclude other elements or steps, and terms such as "a" or "an" do not exclude multiple. Reference numerals in the claims should not be considered restrictive.

Claims

1. A method for shunting a vehicle (100), wherein the vehicle has a defect (106) at a single-wheel steering adjuster (102) of a driven wheel (104) of the vehicle (100), wherein, The torque at the wheel (104) is set according to the steering angle of the opposite wheel (104) of the vehicle (100) for shunting.

2. The method according to claim 1, wherein, Furthermore, the torque is set according to the current angular position of the wheel (104).

3. The method according to any one of the preceding claims, wherein, Furthermore, the torque is set according to the driving torque at the opposite wheel (104).

4. The method according to claim 3, wherein, The torque is set to be lower than the driving torque.

5. The method according to any one of claims 3 to 4, wherein, The torque is set in a manner that is time-off relative to the driving torque at the opposite wheel (104).

6. The method according to any one of the preceding claims, wherein, Reduce the gradient of the torque.

7. The method according to claim 6, wherein, Furthermore, the gradient of the driving torque at the opposite wheel (104) is reduced.

8. The method according to any one of the preceding claims, wherein, Furthermore, the torque is set according to the speed of the vehicle (100).

9. Controller, wherein, The controller is configured to perform, implement, and / or manipulate the method according to any one of the preceding claims in a corresponding device.

10. A computer program product configured to instruct a processor, when executing the computer program product, to perform, implement, and / or manipulate the method according to any one of claims 1 to 8.

11. A machine-readable storage medium on which the computer program product according to claim 10 is stored.

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