Methods and control devices for identifying changes in vehicle wheels

Abstract

The present invention relates to a method for identifying changes (100) in the wheels of a vehicle, wherein the steering force (102) on the wheel and the steering angle (104) of the wheel are evaluated to identify the changes (100).

Description

Technical Field

[0001] This invention relates to a method for identifying changes in vehicle wheels, a corresponding control device, and a corresponding computer program product. Background Technology

[0002] Changes in vehicle wheels (such as pressure loss within the tires) can be identified using wheel rotation speed signals, as such changes typically result in a change in the wheel's rolling radius. Pressure loss at a single wheel, in particular, is easily identifiable due to the increased rotational speed at that wheel relative to the other wheels of the vehicle. Summary of the Invention

[0003] Against this backdrop, utilizing the solution proposed herein, a method for identifying changes in vehicle wheels, a corresponding control device, and a corresponding computer program product are presented according to the independent claims. Advantageous extensions and improvements to the solution proposed herein are derived from the specification and described in the dependent claims.

[0004] Advantages of the invention When changing from winter wheels to summer wheels (or vice versa), tire size and / or rim size may change in diameter, width, or lateral position. This may alter the geometry of the vehicle's wheels or chassis. These geometries may affect the vehicle's driving and / or steering characteristics.

[0005] Changes in the geometry of a wheel can be reflected in changes in the steering force required to steer that wheel. In particular, changes in the wheel's steering roll radius can lead to changes in the steering force.

[0006] The vehicle’s assistance functions, safety functions and / or emergency driving functions can be matched based on the known geometric or mechanical relationships of the chassis and these relationships can be taken into account when they are executed, thereby enabling pre-control of intervention measures.

[0007] In the proposed scheme, changes in the geometric relationships on the wheel and / or the wheel chassis are identified, in particular, by evaluating the relationship between the steering force on the wheel and the steering angle of the wheel.

[0008] The proposed method can reliably identify such changes and, based on this, initiate a learning phase for, for example, assistive functions, safety functions, and / or emergency driving functions.

[0009] A method is proposed for identifying changes in the wheel configuration of a vehicle, wherein the steering force on the wheel and the steering angle of the wheel are evaluated to identify the changes.

[0010] The conception of embodiments of the present invention can be particularly regarded as being based on the ideas and understanding described below.

[0011] In a vehicle, the steering wheels are hinged via steering knuckle arms on their steering knuckles. The steering force of the wheel's steering actuator is applied to the steering knuckle arm via a steering tie rod. Steering actuators can hinge two wheels on a single axle via a shared steering tie rod. Similarly, each wheel can be hinged by its own individual wheel steering actuator. Therefore, steering tie rods are not absolutely necessary. Wheels with individual wheel steering actuators are mechanically uncoupled in terms of steering, or not coupled to the vehicle's steering wheel. The individual wheel steering actuators are controlled by data signals from a central sensor on the vehicle's steering wheel or steering handle.

[0012] The angle of a wheel relative to the vehicle's longitudinal axis is called the steering angle. Within the mechanically possible steering angle range of the wheel, the steering force required to turn the wheel at the steering knuckle is not constant. The kinematics of the chassis affect the variation curve of the steering force within the steering angle range.

[0013] When a wheel is driven or braked, a steering force is required to maintain a constant steering angle, even without changing the steering angle. When a wheel is braked while moving forward or driven while moving in reverse, an outward rotational torque acts on it due to the wheel's geometry. That is, without a supporting steering force, the wheel will pivot outwards when viewed from the vehicle's longitudinal axis. When a wheel is driven forward, an inward rotational torque acts on it. Therefore, without a supporting steering force, the wheel will deflect inwards towards the vehicle's longitudinal axis.

[0014] During both support and active steering, steering force depends primarily on the wheel's rolling radius, in addition to the steering angle. The rolling radius is a characteristic parameter of the wheel suspension / steering system. It refers to the distance between the axis of rotation of the steering motion and the wheel's contact point, measured along the direction of the projection of the axis of rotation onto the road surface (i.e., perpendicular to the wheel within the road surface). Steering force can also depend on ground conditions, tire width, vertical load on the wheel, and other factors.

[0015] Here, a change in at least one of these factors can be identified from steering force and steering angle. In particular, a change in steering roll radius can be identified as such a change.

[0016] The changes can be identified as variations in tire type and / or rim type. In particular, different wheels can be installed. Identifying wheel variations is crucial for vehicle safety systems, assistance systems, and emergency driving capabilities, enabling the prediction of the effectiveness of interventions based on known behaviors from previous interventions.

[0017] The current steering force variation curve with respect to steering angle can be compared with at least one learned steering force variation curve with respect to steering angle for at least one known tire type and / or rim type. The tire type and / or rim type can be identified using the result of this comparison. The wheels used by the vehicle to date can be learned, and the steering forces generated under specific interventions can be stored. During these interventions, it can be identified whether known wheels or previously unknown wheels were installed.

[0018] The change can be identified by the change in steering force at a specific steering angle. With the wheels fixed, the steering force depends on the steering angle. Therefore, the change in wheel position can be identified from the change in steering force at that steering angle.

[0019] The steering torque on the wheel can be derived from the steering force, steering knuckle arm, and steering angle. The steering torque can also be applied directly to the wheel by a rotary steering actuator. Changes in the wheel can be identified by observing the variation of the steering torque with respect to the steering angle. In particular, the steering torque variation curve can be observed.

[0020] The steering force can be derived from the electrical parameters of the wheel's steering actuator. The steering force is primarily proportional to the motor current of the steering actuator; the higher the motor current, the greater the steering force.

[0021] This steering force is particularly useful during vehicle maneuvering or acceleration. During maneuvering, such as parking or pulling out of a parking space, the vehicle travels at low speed and a large steering angle is set. Due to the low speed, a large steering force is generated. Therefore, changes can be identified particularly well during maneuvering. During acceleration, there is a smaller potential hazard because even if wheel identification is incorrect, the vehicle's behavior during acceleration is relatively predictable. Conversely, incorrect identification during braking can have safety-critical consequences.

[0022] The changes can also be identified using at least one of the following information groups: steering speed, accelerator pedal position, braking pressure of the vehicle's braking system, longitudinal acceleration of the vehicle, lateral acceleration of the vehicle, vertical acceleration of the vehicle, vehicle speed, yaw angle of the vehicle, longitudinal slope of the road below the vehicle, lateral slope of the road, suspension compression of the wheel, rotational speed of the wheel, rotational speed of at least one other wheel of the vehicle, rainfall information, and temperature information.

[0023] Using other parameters can make identification more robust. For example, driving conditions can be identified by the rate of change of steering speed, i.e., the steering angle. Similarly, driving conditions can be identified by the position of the accelerator pedal, also known as the gas pedal. The accelerator pedal is typically only operated when the brake pedal is not engaged. Thus, acceleration can be distinguished from braking. Braking pressure can also characterize driving conditions. When braking pressure is greater than zero, the vehicle is generally not accelerated. High braking pressure is expected to require high counter-steering force. Based on the vehicle's acceleration in different spatial directions, driving conditions where steering force is not a significant reference point can be identified. For example, highly dynamic driving conditions can be discarded for identification. Vehicle speed and its derivative can also be used to distinguish driving conditions. Large yaw angles (i.e., the degree to which the vehicle's longitudinal direction deviates from its direction of motion about the ground) characterize dynamic driving conditions, allowing for the suspension of identification of changes in dynamic driving conditions. The road gradient beneath the vehicle affects the vertical load on the vehicle's wheels. Changes in the vertical load on the wheels cause changes in steering force, which are independent of wheel variations. Similarly, a higher steering force is generated when the wheel is compressed than when it rebounds. In extreme cases, the wheel may lift off the ground, and the steering force drops to near zero. The vehicle's wheel speed can also be used to identify driving conditions where wheel slippage detection is less reliable, such as when the wheels are slipping. Rain or general precipitation reduces the traction between the wheel and the ground. This reduces the required steering force, making wheel slippage detection difficult. Ambient temperature can be used to identify icing tendencies or generally expected traction with the ground. For example, at low temperatures, the wheel's traction on the ground may decrease, making wheel slippage detection difficult.

[0024] This method is preferably implemented by a computer, for example, in software or hardware, or in a hybrid form in a driver assistance system.

[0025] The proposed solution also provides a control device configured to perform, manipulate, or implement the steps of a variation of the proposed method in a corresponding apparatus.

[0026] The control device 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 to read in or output data wirelessly and / or via a wired connection. The interface can also be a software module, for example, existing on the same microcontroller along with other software modules.

[0027] Also advantageous is a computer program product or computer program containing 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 used to perform, implement, and / or manipulate the steps of any of the methods described above when the program product or program is run on a computer, control device, or device.

[0028] It should be noted that this document describes some possible features and advantages of the invention with reference to different embodiments. Those skilled in the art will recognize that features of the control device and method can be appropriately combined, adjusted, or replaced to derive further embodiments of the invention. Attached Figure Description

[0029] Embodiments of the present invention will now be described with reference to the accompanying drawings, but the drawings and descriptions should not be construed as limiting the present invention.

[0030] Figure 1 A schematic diagram illustrating the use of a method according to one embodiment to identify changes in vehicle wheels is shown; and Figure 2 A schematic diagram is shown illustrating the identification of changes in vehicle wheels using an extended method according to one embodiment.

[0031] The accompanying drawings are schematic only and are not drawn to scale. The same reference numerals indicate the same or equivalent features. Detailed Implementation

[0032] Figure 1 A schematic diagram is shown illustrating the identification of a change 100 in a vehicle wheel using a method according to one embodiment. This change 100 is identified by using a steering force 102 on the wheel and a steering angle 104 of the wheel.

[0033] Here, the steering force 102 and steering angle 104 are read in by the vehicle's data processing unit 106, and the change 100 is output by the data processing unit 106.

[0034] In one embodiment, the steering force 102 at a specific steering angle 104 is compared with a stored value of the steering force 102 at that specific steering angle 104 to identify a change 100.

[0035] In one embodiment, the change in the wheel's steering roll radius 108 is output as variation 100. Here, the steering roll radius 108 is the distance between the center plane of the wheel and the point where the steering axis of the wheel's steering knuckle intersects the ground beneath the wheel. The steering roll radius 108 and its variation can be calculated using physical equations.

[0036] In one embodiment, the data processing device 106 reads the steering torque 110 and steering angle 104 on the wheel.

[0037] In one embodiment, the variation 100 output wheel is a moderate change of the identified tire and / or rim, such as when changing from a winter wheel with a winter tire on a first rim to a summer wheel with a summer tire on a second rim; when replacing a worn tire with a new tire on the same rim; and / or when changing from one rim model to another rim model on the same tire.

[0038] In one embodiment, the curve of the steering force 102 as a function of the steering angle 104 is evaluated to identify the variation 100.

[0039] In one embodiment, the curve of change of steering force 102 is compared with a stored curve of change. In particular, the curve of change is evaluated during at least one specific driving situation to identify change 100. This driving situation is particularly a maneuver at low speed and with a large steering angle or a large change in steering angle over a short period of time. However, this driving situation could also be an acceleration phase of the vehicle at a small steering angle. During maneuvering, the steering force 102 used to change the steering angle 104 can be evaluated; during acceleration, the steering force 102 used to maintain the steering angle 104 can be evaluated. The steering force 102 during maneuvering can be in the same direction, while the steering force 102 during acceleration can be in the opposite direction.

[0040] In one embodiment, the motor current of the steering actuator of the wheel is measured as a measure of the steering force 102, and the steering force 102 is derived from the motor current.

[0041] Figure 2 A schematic diagram is shown illustrating the identification of changes 100 in vehicle wheels using an extended method according to one embodiment. The method is essentially the same as... Figure 1The method is the same as in [previous section]. In addition, at least one additional parameter is read in here to identify variation 100.

[0042] In one embodiment, in addition to the steering force 102 or steering torque and steering angle 104, a steering speed 200 is also read in. The steering speed 200 can be used to identify the dynamic characteristics of the steering process. During steering processes with high steering speeds 200, the change 100 has a particularly strong effect.

[0043] In one embodiment, the position 202 of the vehicle's accelerator pedal or gas pedal is read. When the gas pedal is pressed deeply, the vehicle accelerates violently, and the change 100 will have a strong impact on the measured steering force 102.

[0044] In one embodiment, the braking pressure 204 of the vehicle's braking system is read in. The braking pressure 204 can be used to identify vehicle braking. Here, the timing of braking by the auxiliary system can also be identified from the braking pressure 204. During braking, the identification of changes 100 can be paused to avoid false identification.

[0045] In one embodiment, the vehicle speed 206 is read in. Vehicle speed 206 can be effectively used to identify driving situations suitable for recognizing changes 100. In particular, vehicle speed 206 can effectively identify maneuvering and acceleration situations.

[0046] In one embodiment, the slope 208 of the ground beneath the vehicle is read. A sloping surface can cause the vehicle's center of gravity to shift relative to its contact point with the ground. A sloping surface results in wheels on the downhill side bearing a higher load, while wheels on the uphill side bear a lighter load. This uneven distribution of wheel load can hinder or distort the recognition of variation 100. Therefore, recognition can be paused from the predetermined slope 208.

[0047] In one embodiment, these input variables are processed in a neural network to identify the change 100.

[0048] The possible embodiments of the present invention will be summarized again below, or stated in slightly different terms.

[0049] A method for identifying steering roll radius and tire type from steering force is proposed.

[0050] For many years, all passenger cars have been equipped with electric power steering systems. The trend is towards removing the mechanical connection between the steering wheel and the vehicle's wheels (steer-by-wire). The next possible step is to drive the steering angle of each wheel on the front axle separately. Another development, already offered as standard equipment in some vehicles, is rear-wheel steering systems that are always implemented as steer-by-wire, sometimes even with each wheel controlled independently.

[0051] Wheel speed has been used to determine various other information, such as tire pressure or the coefficient of friction μ between the tire and the road surface, and also for identification within the range of homologous tires used in vehicles.

[0052] However, the proposed solution addresses the time following wheel replacement and involves enabling the vehicle and its controls to be automatically and optimally configured, while ensuring improved tire recognition.

[0053] Currently, vehicles cannot reliably identify tire changes, such as between summer and winter wheels. Therefore, relying solely on wheel speed and existing signals for identification does not provide a reliable and definitive match. The identified tire type often switches back and forth between, for example, two tires, and the associated target tire pressure recommendations also change. Wheel changes, due to differences in rim offset, can cause (unexpected) changes in vehicle driving characteristics, especially due to changes in the steering roll radius. This is also crucial for safety. By applying the solution proposed in this paper, information about wheel changes and the resulting changes in driving dynamics can be determined without additional sensors using available signals from the steering system, and this information is further provided to ESP for vehicle stability.

[0054] In the proposed scheme, the steering force required under specific driving conditions is used to determine the wheel's steering roll radius. This allows for reliable identification of the mounted wheels. Based on performance, learning can be performed, and the scheme can then be used only to identify known wheels. Alternatively, the system can autonomously identify previously unknown tires.

[0055] This method can likely be extended to other feature parameters. In particular, the steering roll radius is an important parameter that is well-suited to this method.

[0056] Automakers typically pre-define wheel options for specific vehicle models and vehicles of the same origin. In some countries, vehicles can only use winter and summer wheels of the same category (i.e., diameter, width, and a set of characteristics). In other countries, there is significantly more room for flexibility, allowing for some deviation (especially in width), and wheels from different origins may also be installed due to end-user errors or misjudgments. Even while maintaining roughly the same outer diameter, the rim diameter can sometimes vary. If summer and winter wheels are not mounted on rims with identical structures, the rim offset will also differ, resulting in subtle differences, particularly in the lateral position of the tires on the vehicle.

[0057] The lateral distance of the wheel center plane relative to the steering axis defined by the vehicle's suspension structure is called the steering roll radius (rs).

[0058] Steering roll radius has a significant impact in various driving situations. The first is when turning in place, such as when parking. Here, a larger steering roll radius acts as a lever arm around the steering axis, directly resulting in greater steering force, especially when the wheels are braked. Therefore, this is a very suitable scenario for calibrating the proposed function and identifying the mounted tires.

[0059] In the case of a single-wheel actuator, the required torque on each side can be directly obtained by converting the motor current into a measurable variable; for a central actuator, the total torque can be used. Because of the force changes during parking, which are directly related to the required actuator torque, it is possible to identify if a wheel has been replaced. This can then be automatically verified based on other parameters or driving conditions.

[0060] The reason for additional calibration / verification is that steering force can vary depending on the load or the road surface. Furthermore, tire radius is a crucial factor for tire type identification. Therefore, signals from the wheel speed sensors can be additionally utilized.

[0061] If an independent wheel steering system exists, braking or driving is another suitable option for determining the steering roll radius. In this case, the steering roll radius, together with the longitudinal force, generates a moment about the steering axis. However, compared to parking, braking driving conditions have significantly higher safety requirements and are more critical for safety. Therefore, the advantage of the proposed approach lies in using non-critical situations (such as parking or straight-line driving) for identification and calibration. Using a data-driven method, the steering roll radius and tire type can be reliably determined.

[0062] Therefore, the core of the proposed solution describes using steering torque or steering force in the actuator and steering angle to determine the steering roll radius. The steering roll radius is then assigned to homogeneous tires to identify the tire type.

[0063] Other signals present in the vehicle can also be used to improve this recognition (e.g., by combining it with data from the ESP) and to make it applicable to different driving conditions. Other possible signals include: steering speed, accelerator pedal position, brake pressure, longitudinal, lateral and vertical acceleration, vehicle speed, vehicle yaw angle, longitudinal and lateral slope of the road, suspension compression, wheel speed, as well as information from the rain sensor and external temperature.

[0064] The more of these signals available, the more robust the identification process will be. Influences to be identified include, for example: steering behavior (smooth / high frequency, fast / slow), whether the vehicle is accelerating or decelerating, overall driving conditions, vehicle load, longitudinal and lateral road gradients, tire pressure, and estimates of the tire / road friction coefficient.

[0065] To assess the correlation between individual signals, simple equations are applied. To account for multiple effects and perform calibration during continuous operation, data-driven methods can be used. Regardless of the chosen method and implementation, the identified parameters can then be used in critical situations (such as driving and braking) to improve the handling of driving dynamics control.

[0066] The driving actions mentioned can be triggered partially or intentionally, or they can wait until the vehicle is already in that state of motion. Intentionally applying slight braking to the wheels is already existing technology in the field of ESP.

[0067] Information derived from steering data can then be used in the vehicle. In many vehicles, ESP values ​​are recalibrated after tire changes. A simple application is to automatically trigger this calibration when a tire change is detected. In other applications, this information can be used to directly control individual systems (e.g., ABS, ESP) in different ways, thereby improving safety. Changes in the steering roll radius also significantly affect vehicle behavior during braking, especially in situations with uneven friction coefficients (such as braking on surfaces with varying coefficients of adhesion, μ-split braking). Here, a change in the steering roll radius sign can have fatal consequences, as the wheel rotation direction may reverse, leading to unexpected driving situations. In one application example, a warning could be issued if the driver has installed inappropriate wheels to prevent safety-critical situations.

[0068] Braking can assist steering, which is particularly important for fault-tolerant safety and ASIL ratings. This involves braking the wheels. Due to the existence of a steering roll radius, a steering torque is generated, causing the wheels to rotate, where the yaw moment of the entire vehicle is not considered. These interventions are typically based on a known steering roll radius to better evaluate the effect (pre-control). Therefore, in another application example, the available information provided by sensors determining braking and steering during normal operation is used to determine the steering roll radius and other possible characteristic parameters. Subsequently, the vehicle is able to achieve better performance and ensure safety at a known operating point. Thus, the scheme proposed in this paper helps to guarantee the performance of degradation mechanisms used in the design of the vehicle and actuator architecture and assumed to be functional. In another embodiment, the steering roll radius is continuously monitored to ensure, for example, that the effect chain required for braking steering is intact and does not exceed the tolerances necessary for this function. In this case, with the scheme proposed in this paper, such monitoring can provide early warning of erroneous behavior or potential defects in the vehicle.

[0069] The full potential of the proposed solution can only be realized by considering other sensors within the vehicle. Whether simply to identify whether a wheel has been replaced, or to directly reparameterize the model or driving dynamics control, the solution demonstrates significant potential. It may also be able to determine additional vehicle characteristics. The focus is on achieving these additional functionalities. If this makes the sensor redundant, the overall system cost can be reduced. In any case, data processing is required to reliably determine relevant information. In the simplest case, changes can be detected, leading to inferences that a wheel may have been replaced or the steering roll radius may have changed, or in any case, prompting a need to recalibrate stored parameters.

[0070] Finally, it should be noted that terms such as "having" or "comprising" do not exclude the presence of other elements or steps, and terms such as "a" do not exclude plural cases. Reference numerals in the claims should not be considered limiting.

Claims

1. A method for identifying changes (100) in the wheels of a vehicle, wherein a steering force (102) on the wheel and a steering angle (104) of the wheel are evaluated to identify the changes (100).

2. The method according to claim 1, wherein, The change in the steering rolling radius (108) of the wheel is identified as the change (100).

3. The method according to any one of the preceding claims, wherein, Changes in tire type and / or rim type are identified as the changes (100).

4. The method according to claim 2, wherein, The current steering force variation curve with respect to the steering angle (104) is compared with a learned steering force variation curve with respect to the steering angle (104) for at least one known tire type and / or rim type, wherein the tire type and / or rim type is identified by using the result of the comparison.

5. The method according to any one of the preceding claims, wherein, The change (100) is identified by the change in the steering force (102) at a specific steering angle (104).

6. The method according to any one of the preceding claims, wherein, The steering force (102) is derived from the electrical parameters of the steering actuator of the wheel.

7. The method according to any one of the preceding claims, wherein, Steering force (102) is used during the shunting or acceleration process of the vehicle.

8. The method according to any one of the preceding claims, wherein, The change (100) is further identified using at least one piece of information selected from the following information groups: steering speed (200), position of the vehicle's accelerator pedal (202), braking pressure of the vehicle's braking system (204), longitudinal acceleration of the vehicle, lateral acceleration of the vehicle, vertical acceleration of the vehicle, vehicle speed (206), yaw angle of the vehicle, longitudinal slope of the road below the vehicle, lateral slope of the road, suspension compression of the wheel, wheel speed, speed of at least one other wheel of the vehicle, rainfall information, and temperature information.

9. A control device, wherein, The control device is configured to perform, implement, and / or manipulate the method described in any of the preceding claims within a corresponding apparatus.

10. A computer program product configured to, when the computer program product is executed, direct a processor to execute, implement, and / or manipulate the method according to any one of claims 1 to 8.

11. A machine-readable storage medium having a computer program product according to claim 10 stored thereon.

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