DE102022112552A1 - METHOD FOR DETERMINING STABILITY OF A VEHICLE - Google Patents

Abstract

Method for determining stability of a vehicle (1) while driving, comprising the steps:a) receiving (S1) a yaw rate measurement signal (Sω) of a yaw rate sensor (4) of the vehicle (1), wherein the yaw rate measurement signal (Sω) has a plurality of in Dependence of a time (t) measured yaw rate measurement values (ω1, ω2, ..., ωn) includes,b) determining (S4) a slope (St) of the yaw rate measurement signal (Sω), andc) determining (S6) that the vehicle ( 1) is in an unstable state if the determined slope (St) of the yaw rate measurement signal (Sω) is greater than a predetermined slope threshold value (Sts) and an instantaneous speed (V) of the vehicle (1) is greater than a predetermined speed threshold value (VS). .

Description

The present invention relates to a method for determining the stability of a vehicle while driving, a corresponding computer program product, a corresponding control device for a vehicle, a corresponding sensor device for a vehicle and a vehicle.

Many vehicle systems and driver assistance systems require a value of a yaw rate of the vehicle as an input variable for their calculations, for example to localize the vehicle, determine the orientation or the vehicle's own movement. In particular, vehicle systems for stabilizing driving dynamics, such as the electronic stability program (ESP, also called Electronic Stability Control (ESC)), compare wheel sensor data, steering sensor data and yaw rate sensor data of the vehicle in order to assess vehicle stability. If an unstable state of the vehicle is determined, the vehicle system can take measures to stabilize it, such as targeted braking of individual wheels in order to counteract the vehicle swerving.

For example, from the DE 19 912 332 A1 a device for increasing driving stability in a vehicle with an automatic transmission is known. The device includes a detection device for detecting a spinning process. The detection device includes wheel speed sensors and a yaw rate sensor. The detection device is set up to output a signal corresponding to a spinning process. To increase driving safety, it is provided that the transmission control switches the automatic transmission to the neutral position when the signal generated by the detection device exceeds a predetermined threshold value.

Against this background, an object of the present invention is to provide a method and corresponding computer program product, a control device and sensor device for a vehicle and a corresponding vehicle, with which an improved determination of the stability of a vehicle while driving is possible.

1. a) Empfangen eines Gierratenmesssignals eines Gierratensensors des Fahrzeugs, wobei das Gierratenmesssignal eine Mehrzahl von in Abhängigkeit einer Zeit gemessenen Gierratenmesswerten umfasst,
2. b) Ermitteln einer Steigung des Gierratenmesssignals, und
3. c) Ermitteln, dass sich das Fahrzeug in einem instabilen Zustand befindet, wenn die ermittelte Steigung des Gierratenmesssignals größer als ein vorbestimmter Steigungsschwellwert ist und eine momentane Geschwindigkeit des Fahrzeugs größer als ein vorbestimmter Geschwindigkeitsschwellwert ist.

According to a first aspect, a method for determining stability of a vehicle while driving is provided. The procedure includes the steps:

1. a) receiving a yaw rate measurement signal from a yaw rate sensor of the vehicle, wherein the yaw rate measurement signal comprises a plurality of yaw rate measurement values measured as a function of a time,
2. b) determining a slope of the yaw rate measurement signal, and
3. c) Determine that the vehicle is in an unstable state if the determined slope of the yaw rate measurement signal is greater than a predetermined slope threshold value and an instantaneous speed of the vehicle is greater than a predetermined speed threshold value.

By determining the slope of the yaw rate measurement signal, i.e. the temporal change in the yaw rate measurement signal, an abrupt and rapid increase in the yaw rate of the vehicle can be detected while driving. By comparing the determined slope of the yaw rate measurement signal with the predetermined slope threshold value, an increase in the yaw rate that is above the slope threshold value can be characterized as an unstable state of the vehicle. Consequently, vehicle instability while driving, such as lurching or swerving of the vehicle, can be better detected. In response to the vehicle instability detected in this way, automatic measures can be taken to stabilize the vehicle, such as intervention in the steering system and in the engine and transmission control of the vehicle.

The vehicle is, for example, a motor vehicle, such as a passenger car or a truck.

The method is used in particular to determine vehicle instability, which is characterized by a rapid rotation of the vehicle (yaw) about its vertical axis (yaw axis). The method is used in particular to determine vehicle instability in relation to lateral dynamics of the vehicle. Yaw rate is an angular velocity with respect to rotation about the vertical axis of the vehicle. The yaw rate measurement signal, which includes the multiple yaw rate values, describes in particular a time course of the yaw rate. One can also say that the yaw rate measurement signal is a time-dependent yaw rate measurement signal. The slope of the yaw rate measurement signal is the change in the yaw rate measurement signal over time. In other words, the slope of the yaw rate measurement signal is the time derivative of the yaw rate measurement signal. The slope of the yaw rate measurement signal can therefore also be referred to as yaw rate acceleration.

The yaw rate sensor has, for example, a gyroscope.

In step c), the method includes, for example, determining whether the determined slope of the Yaw rate measurement signal is greater than the predetermined slope threshold value.

Determining the slope of the yaw rate measurement signal can, for example, include a computer-aided adjustment (fitting) of a linear function to the yaw rate measurement values of the yaw rate measurement signal. Determining the slope of the yaw rate measurement signal can be carried out, for example, using a statistical method. In particular, determining the slope of the yaw rate measurement signal can include forming a (simple) linear regression with or via the yaw rate measurement values. The slope (time derivative) of the linear function (straight line) determined in this way can then be checked (e.g. whether it is steep enough), in particular whether this slope exceeds the slope threshold value. This type of slope determination can also be done with limited storage space and/or limited computing time, and therefore does not require too many resources. However, other known types of slope determination are also possible.

The method may, for example, include storing the received yaw rate measurements in a memory. The memory has, for example, a ring buffer (“ring buffer”). A maximum buffer length is, for example, 20 or more, 30 or more and/or 50 or more. The method can be used, for example, to check whether a sufficient amount of yaw rate measurement values is stored in the memory (e.g. 20 or more, 30 or more and/or 50 or more values) in order to determine the slope. Whether a sufficient amount of determined yaw rate measurement values are stored in the memory also depends, for example, on the update rate of the yaw rate measurement values or the yaw rate measurement signal or the corresponding software routine or software module for determining the slope of the yaw rate measurement signal. For example, with an update rate of around 40ms, 10 values in memory may be a sufficient amount. With an update rate of around 20 ms, e.g. B. 20 values in memory would be a sufficient amount.

Before determining the slope, the method can, for example, also include subtracting a predetermined yaw rate offset value from each yaw rate value in order to compensate for influences of the measurement method (e.g. a so-called bias or a so-called drift).

The method is used in particular to determine vehicle instability as a function of the current speed of the vehicle. The current speed of the vehicle is in particular a current speed of movement of the vehicle. Since instabilities in driving dynamics predominantly occur at high speeds, the method takes into account current speeds of the vehicle above a speed threshold value.

• Empfangen mindestens eines Geschwindigkeitswertes eines Geschwindigkeitssensors des Fahrzeugs, und
• Ermitteln der momentanen Geschwindigkeit des Fahrzeugs basierend auf dem mindestens einen empfangenen Geschwindigkeitswert.

According to one embodiment, the method comprises the steps:

• Receiving at least one speed value from a speed sensor of the vehicle, and
• Determining the current speed of the vehicle based on the at least one received speed value.

The speed sensor has, for example, an acceleration sensor, a wheel sensor, a wheel speed sensor and/or a gyroscope.

For example, multiple speed values (e.g. based on repeated speed measurements) are received by the vehicle's speed sensor and the current speed of the vehicle is determined by averaging the multiple speed values. The current speed can also be determined by the speed sensor itself and transmitted as a value to the control device.

• Ermitteln, ob die momentane Geschwindigkeit des Fahrzeugs größer als der vorbestimmte Geschwindigkeitsschwellwert ist, und
• Ausführen der Schritte b) und c), wenn ermittelt wird, dass die momentane Geschwindigkeit des Fahrzeugs größer als der vorbestimmte Geschwindigkeitsschwellwert ist.

According to a further embodiment, the method comprises the steps:

• Determine whether the current speed of the vehicle is greater than the predetermined speed threshold, and
• Execute steps b) and c) if it is determined that the current speed of the vehicle is greater than the predetermined speed threshold.

Since instabilities in driving dynamics occur predominantly or exclusively at high speeds, computing efficiency can be increased by carrying out steps b) and c) only in the case in which the current speed of the vehicle is greater than the predetermined speed threshold value.

According to a further embodiment, the speed threshold is 50 km/h or more, 70 km/h or more and/or 100 km/h or more.

According to a further embodiment, the slope threshold value is in the range between 10 and 30 º/s ² , between 15 and 30 º/s ² , between 18 and 30 º/s ² and/or between 20 and 30 º/s ² and/or the slope threshold is 20 º/s ² .

• Ermitteln des Steigungsschwellwerts in Abhängigkeit der momentanen Geschwindigkeit des Fahrzeugs.

According to a further embodiment, the method comprises the step:

• Determining the gradient threshold depending on the current speed of the vehicle.

The slope value of the yaw rate measurement signal (i.e. the extent of the change in the yaw rate over time), at which a vehicle enters an unstable state with respect to driving dynamics, in particular lateral dynamics, depends on the speed of movement of the vehicle. In particular, a larger incline threshold value must be used for a faster travel speed.

By dynamically determining the slope threshold depending on the current speed of the vehicle, a non-critical state of vehicle stability can be distinguished even better and more differentiated from a critical state of vehicle stability.

In other embodiments, however, the gradient threshold value can also be a static quantity and/or independent of the current speed of the vehicle.

According to a further embodiment, the slope threshold value is determined depending on the current speed of the vehicle based on a predetermined assignment, and the predetermined assignment is an assignment of empirically determined slope values of a yaw rate measurement signal of a test vehicle to speed values.

The predetermined assignment is stored, for example, in a memory of a corresponding control device of the vehicle.

If the current speed of the vehicle is known, the associated gradient threshold value can thus be determined based on the predetermined assignment, for example selected and/or read from it.

According to a further embodiment, the slope threshold value for the current speed of the vehicle is determined by interpolating the empirically determined slope values of the predetermined assignment.

If the predetermined assignment does not contain an entry of a slope threshold value for the determined current speed of the vehicle, the slope threshold value for the current speed can be determined by interpolating the existing entries of the slope threshold values of the predetermined assignment.

In embodiments, the slope threshold value for the current speed of the vehicle can also be determined by extrapolating the empirically determined slope values of the predetermined assignment.

According to a further embodiment, the slope values of the predetermined assignment are determined empirically based on multiple types of driving maneuvers, and the multiple types of driving maneuvers include a lane change, a freeway exit, cornering and/or a circular drive, and/or the slope values of the predetermined assignment are determined empirically for a vehicle type , which corresponds to a vehicle type of the vehicle.

The driving maneuver types are, in particular, safe driving maneuver types; one can also say intended or permitted types of driving maneuvers.

It is advantageous to determine the slope values of the predetermined assignment empirically based on several types of driving maneuvers, since the maximum slope of the yaw rate measurement signal for which the vehicle is still in a stable state depends not only on the speed of movement of the vehicle but also on the type of driving maneuver. Furthermore, the said maximum gradient also depends on the vehicle type.

Because the multiple types of driving maneuvers and/or the respective vehicle type are taken into account in the empirical determination of the slope values of the predetermined assignment, an unstable driving state dependent on the yaw rate can be determined even better and in a more differentiated manner.

1. i) Empfangen mindestens eines Wertes einer momentanen Geschwindigkeit eines Testfahrzeugs von einem Geschwindigkeitssensor des Testfahrzeugs,
2. ii) Empfangen eines Gierratenmesssignals eines Gierratensensors des Testfahrzeugs, wobei das Gierratenmesssignal eine Mehrzahl von in Abhängigkeit einer Zeit gemessenen Gierratenmesswerten umfasst,
3. iii) Ermitteln einer Steigung des Gierratenmesssignals, und
4. iv) Ermitteln des Steigungsschwellwerts des Gierratenmesssignals basierend auf der ermittelten Steigung,

wobei die Schritte i) bis iii) für mehrere voneinander verschiedene momentane Geschwindigkeiten des Testfahrzeugs und für mehrere voneinander verschiedene Fahrmanöverarten ausgeführt werden, und wobei in Schritt iv) für jede momentane Geschwindigkeit des Testfahrzeugs der Steigungsschwellwert basierend auf den mehreren ermittelten Steigungen für die mehreren Fahrmanöverarten ermittelt wird.For example, the slope threshold value of the yaw rate measurement signal is determined empirically using a method that includes the following steps:

1. i) receiving at least one value of a current speed of a test vehicle from a speed sensor of the test vehicle,
2. ii) receiving a yaw rate measurement signal from a yaw rate sensor of the test vehicle, wherein the yaw rate measurement signal comprises a plurality of yaw rate measurement values measured as a function of a time,
3. iii) determining a slope of the yaw rate measurement signal, and
4. iv) determining the slope threshold value of the yaw rate measurement signal based on the determined slope,

wherein steps i) to iii) are carried out for several different current speeds of the test vehicle and for several different types of driving maneuvers, and in step iv) the slope threshold value is determined for each current speed of the test vehicle based on the several determined slopes for the several types of driving maneuvers becomes.

Furthermore, this method for determining the slope threshold value of the yaw rate measurement signal can be carried out for several test vehicles, which correspond to different vehicle types.

According to a further embodiment, the predetermined assignment has a plurality of speed values and gradient values correspondingly assigned to the plurality of speed values, and a respective gradient value is based on a maximum value of gradient values empirically determined for the plurality of driving maneuver types for the respective speed value.

For example, for a certain type of vehicle with a current vehicle speed of 80 km/h, an empirically determined gradient value is 5.7 º/s ² when changing lanes and 6.9 º/s ² for a wide curve (“L-curve”) and when driving in a circle 9.7 º/s ² . A maximum value of these three empirically determined gradient values, which were determined accordingly for the exemplary three types of driving maneuvers (lane change, wide curve, circular driving), is therefore 9.7 º/s ² . This means that an incline value based on the maximum value of 9.7 º/s ² can be entered (saved) in the predetermined assignment for a speed value of 80 km/h.

According to a further embodiment, the respective slope value of the predetermined assignment is equal to the maximum value of the slope values empirically determined for the several driving maneuver types for the respective speed value, or is the respective slope value of the predetermined assignment equal to the maximum value multiplied by a distance parameter, in particular a distance parameter in the range between 1 and 3, between 1 and 2 and/or from 1.5.

In the above example, an incline value which is equal to the maximum value of 9.7 º/s ² can be entered (saved) in the predetermined assignment for the speed value of 80 km/h. Alternatively, an incline value which is equal to the maximum value multiplied by the distance parameter can be entered (saved) in the predetermined assignment for the speed value of 80 km/h, for example 14.55 º/s ² (= 9.7 º/ s ² × 1.5).

According to a second aspect, a computer program product is provided that includes instructions that, when the program is executed by a computer, cause it to carry out the method described above.

A computer program product, such as a computer program means, can be provided or delivered, for example, as a storage medium, such as a memory card, USB stick, CD-ROM, DVD, or in the form of a downloadable file from a server in a network. This can be done, for example, in a wireless communication network by transmitting a corresponding file with the computer program product or the computer program means.

According to a third aspect, a control device for a vehicle for determining stability of the vehicle while driving is provided. The control device is designed to carry out the method described above.

The control device is in particular set up to process the computer program product described above (for example on a processor of the control device).

• mindestens einen Gierratensensor, und
• eine wie vorstehend beschriebene Steuereinrichtung.

According to a fourth aspect, a sensor device for a vehicle for determining stability of the vehicle while driving is provided. The sensor device has:

• at least one yaw rate sensor, and
• a control device as described above.

The control device and/or the sensor device can in particular be designed in the form of or as part of a driving assistance system. The driving assistance system serves in particular to support a driver of the vehicle (SAE level 1 or 2) and/or for semi-autonomous or fully autonomous operation of the vehicle (SAE level 3 to 5). The SAE levels are classifications according to the SAE classification system J3016, “Taxonomy and Definitions for Terms Related to On-Road Motor Vehicle Automated Driving Systems,” 2014 by SAE International, an automotive standards organization.

The control device and/or the sensor device (or the driving assistance system) can, for example, be designed, among other things, to localize the vehicle, determine the orientation of the vehicle and/or estimate the vehicle's own movement.

According to a fifth aspect, a vehicle is provided with a control device as described above and/or a sensor device as described above.

The respective unit or device described above or below, such as the control device, can be implemented in hardware and/or software. In the case of a hardware implementation, the respective unit can be designed, for example, as a computer or as a microprocessor. In the case of a software implementation, the respective unit can be designed as a computer program product, as a function, as a routine, as an algorithm, as part of a program code or as an executable object. Furthermore, each of the units or devices mentioned above or below, such as the control device, can also be designed as part of a higher-level control system of the vehicle, such as a central electronic control device (ECU).

The embodiments and features described for the first aspect apply accordingly to the other aspects (second to fifth aspects) and vice versa.

Further possible implementations of the invention also include combinations of features or embodiments described above or below with regard to the exemplary embodiments that are not explicitly mentioned. The person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the invention.

Further advantageous refinements and aspects of the invention are the subject of the subclaims and the exemplary embodiments of the invention described below.

• 1 zeigt eine schematische Draufsicht eines Fahrzeugs mit einer Sensorvorrichtung gemäß einer Ausführungsform;
• 2 zeigt ein Diagramm eines beispielhaften Gierratenmesssignals des Fahrzeugs aus 1;
• 3 zeigt ein Flussablaufdiagramm eines Verfahrens zum Ermitteln einer Stabilität des Fahrzeugs aus 1 während des Fahrens;
• 4 zeigt eine vorbestimmte Zuordnung von empirisch ermittelten Steigungswerten eines Gierratenmesssignals eines Testfahrzeugs zu Fahrzeuggeschwindigkeitswerten ;
• 5 zeigt eine Ansicht ähnlich 2, wobei eine ermittelte Steigung des Gierratenmesssignals gekennzeichnet ist;
• 6 zeigt ein Diagramm eines zeitabhängigen Gierratenmesssignals eines Testfahrzeugs bei einer Kurvenfahrt;
• 7 zeigt ein Diagramm eines zeitabhängigen Gierratenmesssignals eines Testfahrzeugs bei einem Fahrbahnwechsel;
• 8 zeigt eine Steigung des Gierratenmesssignals aus 6 und des Gierratenmesssignals aus 7 jeweils in Abhängigkeit einer Fahrzeuggeschwindigkeit des Testfahrzeugs sowie eine daraus ermittelte geschwindigkeitsabhängige Steigungsschwellwertfunktion; und
• 9 zeigt eine Tabelle mit empirisch ermittelten, geschwindigkeitsabhängigen Steigungswerten von Gierratenmesssignalen des Testfahrzeugs für verschiedene Fahrmanöverarten.

The invention is further explained in more detail using preferred embodiments with reference to the accompanying figures.

• 1 shows a schematic top view of a vehicle with a sensor device according to an embodiment;
• 2 shows a diagram of an exemplary yaw rate measurement signal of the vehicle 1 ;
• 3 shows a flowchart of a method for determining stability of the vehicle 1 during driving;
• 4 shows a predetermined assignment of empirically determined slope values of a yaw rate measurement signal of a test vehicle to vehicle speed values;
• 5 shows a view similar 2 , wherein a determined slope of the yaw rate measurement signal is characterized;
• 6 shows a diagram of a time-dependent yaw rate measurement signal of a test vehicle when cornering;
• 7 shows a diagram of a time-dependent yaw rate measurement signal of a test vehicle when changing lanes;
• 8th shows a slope of the yaw rate measurement signal 6 and the yaw rate measurement signal 7 each depending on a vehicle speed of the test vehicle and a speed-dependent gradient threshold function determined therefrom; and
• 9 shows a table with empirically determined, speed-dependent slope values of yaw rate measurement signals of the test vehicle for various types of driving maneuvers.

In the figures, identical or functionally identical elements have been given the same reference numbers unless otherwise stated.

1 shows a schematic top view of a vehicle 1 with a sensor device 2 according to an embodiment. The vehicle 1 is in the example of 1 a motor vehicle, especially a passenger car. The sensor device 2 is designed, for example, in the form of or as part of a driving assistance system. The sensor device 2 and/or the driving assistance system serves, for example, to support a driver of the vehicle 1. Furthermore, the sensor device 2 and/or the driving assistance system can also be designed for semi-autonomous or fully autonomous operation of the vehicle 1. The sensor device 2 and/or the driving assistance system is designed, for example, to control components of the vehicle 1, such as a braking system, a steering system and a drive system, so that driver assistance, semi-autonomous and/or fully autonomous operation can be carried out. The sensor device 2 and/or the driving assistance system is designed in particular for operation at higher speeds, as usually occurs when driving on roads in local areas and overland areas. In addition, the sensor device 2 and/or the driving assistance system can also be operated at low temperatures Speeds such as those that occur when parking and/or maneuvering, for example, must be designed.

The sensor device 2 includes a control device 3 and a yaw rate sensor 4, for example a gyroscope. The control device 3 is set up to carry out the method described below for determining the stability of the vehicle 1 while driving. The yaw rate sensor 4 is connected wirelessly and/or wired to the control device 3 for transmitting data. The reference number 5 denotes a data connection, such as a line, a data line, a vehicle bus and/or a wireless data transmission, between the yaw rate sensor 4 and the control device 3. The control device 3 can receive a yaw rate measurement signal S _ω from the yaw rate sensor 4 via the connection 5 , which includes a plurality of yaw rate measurements ω ₁ , ω ₂ , ..., ω _n .

The control device 3 is in the in 1 shown embodiment is further coupled with wheel sensors 6, which are attached to the wheels (not shown) of the vehicle 1. The wheel sensors 6 are, for example, wheel angle sensors and/or wheel speed sensors. The wheel sensors 6, for example, provide so-called wheel pulses that characterize the rotations of the wheels. Several pulses can be generated per revolution. In the exemplary embodiment shown, the wheel sensors 6 are also connected wirelessly and/or wired via connections 5 (e.g. lines, data lines, a vehicle bus and/or wireless data transmission) to the control device 3 for transmitting data. Alternatively, they can also be connected to the control device 3 via other connections and/or lines. The control device 3 can in the example of 1 The wheel pulses are also received via connections 5.

The control device 3 is in the exemplary embodiment 1 also coupled to a steering and/or drive device 7. For example, the control device 3 is connected wirelessly and/or wired (e.g. by a line) to the steering and/or drive device 7 via a connection 8 for transmitting data. The control device 3 can send control signals to the steering and/or drive device 7 via the connection 8. The control signals are used, for example, to control a steering angle and/or a longitudinal guidance of the vehicle 1 by controlling the steering device. Alternatively or additionally, the control signals can also serve to automatically accelerate and/or brake the vehicle 1 by controlling the drive device.

In the in 1 In the exemplary embodiment shown, the control device 3 also receives sensor data from surrounding sensors 9. The surrounding sensors 9 can, for example, be designed to detect objects and / or obstacles in the surroundings of the vehicle 1. The environment sensors 9 include, for example, ultrasonic sensors, radar sensors (radio detection and ranging), lidar sensors (light detection and ranging), optical distance sensors and/or cameras.

The sensor device 2 can also include further sensors (not shown), such as a longitudinal acceleration sensor for detecting the longitudinal acceleration of the vehicle 1.

Furthermore, the control device 3 includes a computer program product which has program code means which are stored in a computer-readable medium in order to be able to carry out the method described below for determining the stability of the vehicle. In particular, the computer program product is formed on a processor (not shown) of the electronic control device 3 and is processed there.

The sensor device 2 and/or the driving assistance system requires a reliable yaw rate as an input variable for calculations that are carried out in the control device 3. The calculations are used, for example, to localize the vehicle 1, determine the orientation of the vehicle 1 and/or estimate the vehicle 1's own movement. In particular, the sensor device 2 is used to detect vehicle instability based on data from the yaw rate sensor 4 and thus, for example, a roll of the vehicle. The yaw rate is a rotational angular velocity of the vehicle 1 with respect to a rotation about its vertical axis H (vertical axis H) and describes a speed of a yaw movement of the vehicle 1. It is important to provide a reliable method for determining the stability of the vehicle based on yaw rate measurement signals. In particular, it is important to reliably distinguish between safe driving dynamics states and unsafe driving dynamics states.

2 shows a diagram of an exemplary yaw rate measurement signal S _ω of the yaw rate sensor 4 of the sensor device 2 of the vehicle 1 ( 1 ). The yaw rate measurement signal S _ω represents a time course and is in the diagram in 2 plotted over time t. The yaw rate measurement signal S _ω comprises a plurality of yaw rate measurement values ω ₁ , ω ₂ , ..., ω _n , which were detected by the yaw rate sensor 4 at different times t. The y-axis of the chart in 2 indicates the yaw rate measurement signal S _ω , or the yaw rate measurement values ω ₁ , ω ₂ , ..., ω _n in the unit [°/s]. The unit [°/s] denotes a rotation angle per second with respect to a rotation of the vehicle 1 about the vertical axis H ( 1 ). The x-axis of the chart in 2 indicates the time t.

The plurality of yaw rate measurements ω ₁ , ω ₂ , ..., ω _n were detected by the yaw rate sensor 4 and sent to the control device 3. The control device 3 thus receives the plurality of yaw rate measurement values ω ₁ , ω ₂ , ..., ω _n , which represent the yaw rate measurement signal S _ω .

As in 2 As can be seen, the yaw rate measurement signal S _ω is relatively constant in the period from time t ₀ to t ₁ and has (approximately) the value ω _A . As time progresses from time t ₁ to t ₂ , the yaw rate measurement signal S _ω increases abruptly and sharply to a value ω _B. The increase is essentially linear and/or continuous and has a positive slope. A sharp increase in the yaw rate measurement signal S _ω of the vehicle 1 can be an indication of an unstable state of the vehicle 1 with respect to driving dynamics, in particular lateral dynamics, of the vehicle 1. It is advantageous to distinguish as reliably as possible between an increase in the yaw rate measurement signal S _ω , which corresponds to a permitted driving maneuver such as cornering, and an increase in the yaw rate measurement signal S _ω , which corresponds to an unstable state of the vehicle 1, such as a lurching or swerving of the vehicle 1 , to distinguish.

The following is with reference to 3 a method for determining stability of the vehicle 1 based on a yaw rate measurement signal S _ω is described. 3 shows a flowchart of an exemplary embodiment of the method.

In a first step S1 of the method, the control device 3 receives a yaw rate measurement signal S _ω from the yaw rate sensor 4. The yaw rate measurement signal S _ω comprises a plurality of yaw rate measurement values ω ₁ , ω ₂ , ..., ω _n , which represent a time profile of the yaw rate sensor 4 represent the measured yaw rate of the vehicle 1.

In a second step S2 of the method, the control device 3 determines whether a current speed V (travel speed V) of the vehicle 1 is greater than a predetermined speed threshold V _S. The predetermined speed threshold V _S is, for example, 50 km/h, 70 km/h or 100 km/h. This method step checks whether the travel speed V of the vehicle 1 is in a speed range in which the risk of lurching or other vehicle instabilities plays a role.

For example, in step S2, the control device 3 receives at least one speed value (e.g. wheel pulse) from a speed sensor, such as the wheel sensor 6 ( 1 ), of the vehicle 1. Furthermore, the control device 3 determines the current speed V of the vehicle 1 based on the at least one speed value. For example, in step S2, the control device 3 receives a plurality of speed values from a speed sensor of the vehicle 1 and determines the current speed V of the vehicle 1 based on averaging the plurality of speed values. For example, in step S2, the control device 3 receives one or more wheel pulses from the speed sensor 6 (wheel sensor) and determines the current speed V of the vehicle 1 based on the one or more wheel pulses. For example, in step S2, the control device 3 receives one or more acceleration values from a speed sensor (acceleration sensor) and determines the current speed V of the vehicle 1 based on the one or more acceleration values.

If it is determined in step S2 that the current speed V of the vehicle 1 is not greater than the speed threshold V _S (branch N for “No” in 3 ), then the procedure ends at this point.

However, if it is determined in step S2 that the instantaneous speed V of the vehicle 1 is greater than the speed threshold V _S (branch J for “Yes” in 3 ), then the process continues.

In an optional third step S3 of the method, a slope threshold value Sts can first be determined as a function of the current speed V of the vehicle 1. For example, the slope threshold Sts is based on a predetermined mapping 10 (e.g. Table 10 in 4 ) from empirically determined slope values St _e of a respective test yaw rate measurement signal (similar to the yaw rate measurement signal S _ω ) to determine speed values V _e . The predetermined assignment 10 is stored, for example, in a memory (not shown) of the control device 3 of the vehicle 1.

The slope threshold value Sts can be selected and/or read from the assignment table 10, for example. For example, in step S2 an instantaneous speed V des Vehicle 1 is determined to be 100 km/h, then a gradient threshold value Sts of 16.2º/s ² can be read directly from the allocation table 10.

If the predetermined assignment 10 does not contain an entry of a slope value St _e for the determined current speed V of the vehicle 1, the slope threshold value Sts for the current speed V can also be determined by interpolating the existing entries of the slope threshold values St _e of the predetermined assignment 10. For example, if a current speed V of the vehicle 1 of 110 km/h is determined in step S2, then the empirically determined gradient values St _e can be at a speed V _e of 100 km/h (16.2 º/s ² ) and at a Speed V _e of 120 km/h (22.1 º/s ² ) are interpolated in order to determine a slope threshold value Sts for a current speed V of the vehicle 1 of 110 km/h.

Through the optional step S3 of determining a slope threshold value Sts depending on the current speed V of the vehicle 1, vehicle instability can be recognized even better, in particular more precisely. This is because the extent of the temporal change in the yaw rate at which vehicle instability occurs depends on the travel speed V of the vehicle 1. In particular, for a faster travel speed V, a larger gradient threshold value Sts must be used in order to differentiate more clearly between a permitted driving maneuver and an unstable state.

In a fourth step S4 of the method, the control device 3 determines a slope St of the yaw rate measurement signal S _ω 2 . In other words, an extent of a temporal change in the time-dependent yaw rate measurement signal S _ω is determined in step S4. 5 shows a similar illustration 2 , where the slope St of the yaw rate measurement signal S _ω was plotted.

Optionally, the method checks in step S4 whether there are enough yaw rate measurement values ω ₁ , ω ₂ , ..., ω _n to determine a slope St. For example, the yaw rate measurements ω ₁ , ω ₂ , ..., ω _n are stored in a memory (not shown). The memory can, for example, be designed as a ring memory (e.g. with a maximum buffer length of 50 or another buffer length). The memory is in particular part of the control device 3 or is connected to it directly for data transmission. In the method, for calibrating the measured values (correction of bias and/or drift), for example before storing the yaw rate measured values ω ₁ , ω ₂ , ..., ω _n of each yaw rate measured values 'ω ₁ , ω ₂ , ..., ω _n an offset value can be subtracted.

The slope St can be determined, for example, by computer-aided adjustment (fitting) of a linear function G (straight line G) to the yaw rate measured values ω ₁ , ω ₂ , ..., ω _n . For example, the slope St is determined by forming a (simple) linear regression with the yaw rate measured values ω ₁ , ω ₂ , ..., ω _n .

In a fifth step S5 of the method, the control device 3 determines whether the slope St of the yaw rate measurement signal S _ω determined in S4 is greater than a predetermined slope threshold value Sts. For example, it can be checked whether the slope St of the straight line G determined in step S4 is steep enough to indicate an unstable vehicle condition.

In a first variant of the method, the predetermined slope threshold value Sts used in step S5 can be a static variable which is in particular independent of the current speed V of the vehicle 1. In other words, one and the same value of a predetermined slope threshold Sts can be used for the check in step S5, regardless of what value the current speed V of the vehicle 1 is (as long as it is greater than the speed threshold V _S ). For example, a value of a static slope threshold Sts is in a range between 18 and 30°/s ² .

In a second variant of the method, step S3 is carried out before step S5 (e.g. also before step S4). This means that a gradient threshold value Sts is first determined as a function of the current speed V (dynamic gradient threshold value Sts). In the second variant of the method, the dynamic slope threshold Sts is then applied in step S5.

If it is determined in step S5 that the determined slope St of the yaw rate measurement signal S _ω is not greater than the predetermined (static or dynamic) slope threshold value Sts (branch N for "No" in 3 ), then the procedure ends at this point.

However, if it is determined in step S5 that the determined slope St of the yaw rate measurement signal S _ω ( 5 ) is greater than the predetermined (static or dynamic) slope threshold Sts (branch J for “Yes” in 3 ), then the method is continued and step S6 is carried out.

In a sixth step S6 of the method, the control device 3 determines that the vehicle 1 is in an unstable state.

If it is determined in the method that the vehicle is in an unstable state in terms of driving dynamics, the control device 3 can control the steering/drive device 7 of the vehicle 1 in order to automatically stabilize the vehicle. For example, a steering angle, longitudinal guidance and/or braking of the vehicle 1 can be controlled in this way.

In the 6 until 9 is an empirical determination of the predetermined assignment 10 ( 4 ) illustrated. The 6 until 9 relate in particular to determining the predetermined assignment 10 before the vehicle 1 is put into operation, for example before the vehicle 1 is put into operation for the first time.

While above with reference to the 1 until 5 a method for determining vehicle stability while driving (ie in particular a method for operating the vehicle 1) has been described, illustrate the 6 until 9 a method for determining a slope threshold value Sts before the (e.g. first) commissioning of the vehicle 1.

Like in the 6 and 7 illustrated, the predetermined assignment 10 ( 4 ) can be determined empirically before putting the vehicle 1 into operation, for example based on several different types of driving maneuvers 11, 12. The several types of driving maneuvers 11, 12 include, for example, cornering 11 ( 6 ) and/or a lane change 12 ( 7 ). Although not shown in the figures, the multiple types of driving maneuvers may also include, for example, a highway exit or a circular drive as a special cornering.

The predetermined assignment 10 ( 4 ) can, for example, also be determined empirically before the vehicle 1 is put into operation specifically for a vehicle type that corresponds to a vehicle type of the vehicle 1. This means that a corresponding predetermined assignment (similar to the predetermined assignment 10) can be determined empirically at the factory for each vehicle type produced. The assignment determined empirically in this way (similar to the predetermined assignment 10) can then be stored in a memory of a control device (similar to the control device 3 of the vehicle 1 in 1 ) are saved as configuration data.

As in 6 illustrated, a test drive is carried out with a test vehicle (similar to vehicle 1) at a speed V _e of 100 km/h through a curve (curve 11). For example, a control device of the test vehicle (similar to the control device 3 of the vehicle 1) receives a yaw rate measurement signal S' _ω ( 6 ) of a yaw rate sensor of the test vehicle (similar to the yaw rate measurement signal S _ω of the yaw rate sensor 4 of the vehicle 1). The yaw rate measurement signal S' _ω comprises a plurality of yaw rate measurement values measured as a function of a time t. A slope St _e of the yaw rate measurement signal S' _ω is then determined. In the example of 6 For example, a slope St' _e of 10.8 º/s ² is determined.

As in 7 illustrated, for example, a further test drive is carried out with a test vehicle (similar to vehicle 1) at a speed of 120 km/h with a lane change 12. For example, the control device of the test vehicle (similar to the control device 3 of the vehicle 1) receives a yaw rate measurement signal S'' _ω ( 7 ) of a yaw rate sensor of the test vehicle (similar to the yaw rate measurement signal S _ω of the yaw rate sensor 4 of the vehicle 1). The yaw rate measurement signal S'' _ω comprises a plurality of yaw rate measurement values measured as a function of a time t. A slope St' _e of the yaw rate measurement signal S'' _ω is then determined. In the example of 7 For example, a slope St' _e of 5.2 º/s ² is determined.

Similar test drives are then carried out for several different speeds V _e of the test vehicle and, for example, for other types of driving maneuvers.

8th shows a diagram in which the gradient St _e or St' _e depends on the vehicle speed V _e for the in the 6 and 7 Driving maneuver types 11, 12 shown are shown. A graph is marked with reference number 13, which describes the results of test drives with cornering 11 for speeds between 80 and 170 km/h. A graph is marked with reference number 14, which describes the results of test drives with a lane change 12 for speeds between 80 and 170 km/h.

9 shows results of test drives in a table form.

In 8th a speed-dependent function 15 of the slope threshold value Sts determined from graphs 13 and 14 is shown. The slope threshold function 15 is determined such that it is greater than a maximum value M of the graphs 13 and 14 for each speed V _e . For example, for a specific vehicle type at a current speed, V _e is the test drive vehicle of 80 km/h an empirically determined gradient value St _e , St' _e when changing lanes is 5.7 º/s ² , when driving on a wide curve (“L-curve”) 6.9 º/s ² and when driving in a circle it is 9 .7º/s ² ( 9 ). A maximum value M of these three empirically determined gradient values St _e , St' _e , which were determined for the exemplary three types of driving maneuvers (lane change, wide curve, circular driving), is therefore 9.7 º/s ² . This means that in the predetermined assignment 10 ( 4 ) for a speed value V _e of 80 km/h, an incline value based on the maximum value M of 9.7 º/s ² can be entered (saved).

In the 8th The slope threshold function 15 shown, determined from graphs 13 and 14, can also be determined in such a way that the respective slope value St _e of the predetermined assignment 10 corresponds to the maximum value M multiplied by a distance parameter A. The distance parameter A is, for example, 1.5. In the example above, in the predetermined assignment 10 for the speed value of 80 km/h z. B. a slope value St _e of 9.7 º/s ² can be entered (saved) (St _e = M = 9.7 º/s ² ). Alternatively, an incline value corresponding to the maximum value M multiplied by the distance parameter A can be entered (saved) in the predetermined assignment 10 for the speed value of 80 km/h, for example 14.55 º/s ² (M x A = 9.7 º/s ² × 1.5).

The test drives described with the test vehicle can be carried out for several test vehicles which have different vehicle types. This allows a dynamic gradient threshold Sts to be determined tailored to different vehicle types and in relation to the 1 until 5 procedures described can be used.

Although the present invention has been described using exemplary embodiments, it can be modified in many ways.

REFERENCE SYMBOL LIST

1

vehicle

2

Sensor device

3

Control device

4

Yaw rate sensor

5

Connection

6

Wheel sensor

7

Steering and/or drive device

8th

Connection

9

Environment sensor

10

Assignment

11

Driving maneuver type

12

Driving maneuver type

13

graph

14

graph

15

Slope threshold

A

Distance parameters

G

linear function (even)

H

vertical axis

M

Maximum value

S1-S6

Procedural steps

Sω

Yaw rate measurement signal

S'ω

Yaw rate measurement signal

S''ω

Yaw rate measurement signal

St

pitch

St'

pitch

St''

pitch

Sts

Slope threshold

Ste

slope value

St'e

slope value

t

Time

t1

Time

t2

Time

t3

Time

v

speed

Ve

Speed value

VS

Speed threshold

ω1-ωn

Yaw rate measurements

waa

Yaw rate value

ωB

Yaw rate value

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 19912332 A1 [0003]

Claims (15)

Method for determining stability of a vehicle (1) while driving, comprising the steps: a) receiving (S1) a yaw rate measurement signal (S _ω ) of a yaw rate sensor (4) of the vehicle (1), wherein the yaw rate measurement signal (S _ω ) has a plurality of yaw rate measurements (ω ₁ , ω ₂ , ..., ω _n ) measured as a function of a time (t), b) determining (S4) a slope (St) of the yaw rate measurement signal (S _ω ), and c) determining (S6 ), that the vehicle (1) is in an unstable state if the determined slope (St) of the yaw rate measurement signal (S _ω ) is greater than a predetermined slope threshold value (Sts) and an instantaneous speed (V) of the vehicle (1) is greater than a predetermined speed threshold (V _S ). Procedure according to Claim 1 , comprising: receiving at least one speed value of a speed sensor of the vehicle (1), and determining the current speed (V) of the vehicle (1) based on the at least one received speed value. Procedure according to Claim 1 or 2 , comprising: determining (S2) whether the current speed (V) of the vehicle (1) is greater than the predetermined speed threshold (V _S ), and executing steps b) and c) if it is determined that the current speed ( V) of the vehicle (1) is greater than the predetermined speed threshold (V _S ). Method according to one of the preceding claims, wherein the speed threshold (V _S ) is 50 km/h or more, 70 km/h or more and/or 100 km/h or more. Method according to one of the preceding claims, wherein the slope threshold value (St _S ) is in the range between 10 and 30º/s ² , between 15 and 30º/s ² , between 18 and 30º/s ² and/or between 20 and 30º /s ² and/or 20º/s ² . Method according to one of the preceding claims, comprising: Determining (S3) the gradient threshold value (Sts) as a function of the current speed (V) of the vehicle (1). Procedure according to Claim 6 , wherein the slope threshold value (Sts) is determined as a function of the instantaneous speed (V) of the vehicle (1) based on a predetermined assignment (10), and the predetermined assignment (10) is an assignment of empirically determined slope values (St _e ) of a yaw rate measurement signal (S' _ω , S'' _ω ) of a test vehicle to speed values (V _e ). Procedure according to Claim 7 , wherein the slope threshold value (Sts) for the current speed (V) of the vehicle (1) is determined by interpolating the empirically determined slope values (St _e ) of the predetermined assignment (10). Procedure according to Claim 7 or 8th , wherein the gradient values (St _e ) of the predetermined assignment (10) are determined empirically based on several types of driving maneuvers (11, 12), and the several types of driving maneuvers (11, 12) include a lane change (12), a freeway exit, cornering (11) and/or include a circular drive, and/or wherein the slope values (St _e ) of the predetermined assignment (10) are determined empirically for a vehicle type that corresponds to a vehicle type of the vehicle (1). Procedure according to Claim 9 , wherein the predetermined assignment (10) has a plurality of speed values (V _e ) and gradient values (St _e ) corresponding to the plurality of speed values, and a respective gradient value (St _e ) at a maximum value of empirically determined for the several types of driving maneuvers (11, 12). Slope values (St _e ) for the respective speed value (V _e ). Procedure according to Claim 10 , whereby the respective slope value (St _e ) of the predetermined assignment (10) is equal to the maximum value of the slope values (St _e ) empirically determined for the several types of driving maneuvers (11, 12) for the respective speed value (V _e ), or the respective slope value ( St _e ) of the predetermined assignment (10) is equal to the maximum value multiplied by a distance parameter (A), in particular a distance parameter (A) in the range between 1 and 3, between 1 and 2 and / or 1.5. Computer program product, comprising instructions which, when the program is executed by a computer, cause it to carry out the method according to one of the preceding claims. Control device (3) for a vehicle (1) for determining stability of the vehicle (1) while driving, which is designed to use the method according to one of Claims 1 - 11 to carry out. Sensor device (2) for a vehicle (1) for determining the stability of the vehicle (1) while driving, comprising: at least one yaw rate sensor (4), and a control device (3). Claim 13 . Vehicle (1) with a control device (3). Claim 13 and/or a sensor device (2). Claim 14 .

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