METHOD FOR VERIFYING THE PLASIBILITIES OF A VEHICLE BODY AND DEVICE FOR EXECUTING THE METHOD

Description

[0001] The invention relates to a method for verifying the plausibility of a measured or determined roll rate of a vehicle body and a device for carrying out the method according to claims 1 and 5.

[0002] In vehicle dynamics control systems, such as an ESP (Electronic Stability Program), sensors are used to measure accelerations and yaw rates to detect vehicle movement. These sensors are typically permanently mounted to the vehicle body and, depending on the design, measure up to six degrees of freedom of the vehicle body, consisting of accelerations and yaw rates, along all three axes of the Cartesian vehicle coordinate system. To prevent malfunctions in the vehicle dynamics control systems, the sensor signals must be monitored for plausibility. From the perspective of vehicle dynamics control, the yaw rate (rotational rate) and the lateral acceleration (acceleration in the side direction of the vehicle) are the most important parameters. Accordingly, these sensors are designed to detect at least the yaw rate and often also the lateral acceleration.To monitor plausibility, these two quantities can be converted into one another using additional measured variables. Sensors that detect further degrees of freedom, often all six degrees of freedom, are being used more and more frequently. Therefore, further methods are needed to monitor the plausibility of these additionally detected degrees of freedom.

[0003] Prior art methods for monitoring sensors used to detect vehicle movement generally involve redundant measurement of the relevant parameter by at least two sensors. If the measured values ​​of the redundant sensors deviate too significantly from each other, a defect is detected, as proposed in DE102018204286A1. DE102017208375A1 presents a method for detecting a malfunctioning yaw rate sensor. Specifically, the roll rate is monitored by determining a roll angle from the yaw rate signal and checking whether it is within a valid range. Determining a roll angle from the roll rate signal is subject to errors due to noise and sensor offsets. Therefore, another measured parameter is typically used for support. This results in the inability to identify which measured parameter is the cause of a potential error.German patent DE102004020927A1 presents a method for verifying the functionality of a sensor by comparing the monitored physical quantity with that of another sensor which detects a second physical quantity that can be converted into the monitored physical quantity. As an example, the calculation of a rotation rate about the longitudinal or transverse axis of the vehicle is proposed from measured suspension travel or wheel loads. If the calculated rotation rate deviates too much from the directly measured rotation rate, a fault is detected.

[0004] The methods known from the prior art for monitoring the rotation rates around the longitudinal and lateral axes of a vehicle therefore require either the redundant installation of the corresponding sensors or, alternatively, the installation of sensors for detecting another physical quantity that correlates with the rotation rate. This entails corresponding additional costs.

[0005] Other approaches known from the literature utilize models that simulate the movement of the vehicle body. Using these models, and with one or more input variables (e.g., steering angle and vehicle speed), statements can be made about the movement of the vehicle body and thus about the rotation rates around the longitudinal and lateral axes of the vehicle. These statements can be compared with the sensor's measurement signals, and deviations can be determined. These model-based approaches are highly dependent on the quality of the modeling and the model parameters. The model parameters must be determined anew or estimated in a complex manner for each vehicle variant, which involves a corresponding increase in effort.

[0006] A generic method is known from DE102007037508 A1, wherein a roll rate plausibility check is performed by comparing a roll rate sensor value with a roll rate estimate based on sensor signals from a lateral acceleration sensor. WO 2021 / 059845A1 discloses an estimation of the roll rate of a vehicle based on a change in lateral acceleration.

[0007] The object of the invention is to provide a method for verifying the plausibility of a vehicle's recorded or determined roll rate, which can be carried out with minimal computational effort. Furthermore, a device for carrying out the method is also to be disclosed.

[0008] This problem is solved by the features of claims 1 and 5. Disclosure of the invention

[0009] A first aspect of the invention discloses a computer-implemented method for verifying the plausibility of a measured or determined roll rate φ̇ of a vehicle body about a longitudinal axis of the vehicle, in which a change in lateral acceleration äy or a lateral jerk jy is calculated from a measured or determined lateral acceleration ay in the transverse direction y of the vehicle, on the basis of which or on the basis of which a plausible value or a plausible range for the roll rate φ̇ is determined.

[0010] In this method, the plausible range or value for the roll rate φ̇ can be determined on the basis of a functional dependence of the roll rate φ̇ on the change in lateral acceleration ȧy or on the lateral jerk jy.

[0011] The functional dependence is a linear dependence and is formed by a straight line with a slope of 1 / g, where g is the acceleration due to gravity.

[0012] Specifically, the invention provides a computer-implemented method for verifying the plausibility of a measured or determined roll rate (φ̇) of a vehicle body about a longitudinal axis of the vehicle, wherein the method comprises the following steps: a) Measuring or determining the roll rate (φ̇) of the vehicle body, b) Measuring or determining a lateral acceleration (ay) in the lateral direction (y) of the vehicle in a vehicle-fixed coordinate system, c) Calculating a change in lateral acceleration (äy) or a lateral jerk (jy) as the time derivative of the lateral acceleration (ay), d) Determining a straight line with a slope of 1 / g, where g is the acceleration due to gravity, and where the straight line represents a linear dependence of the roll rate (φ̇) on the change in lateral acceleration (äy) or on the lateral jerk (jy), e) Determining a plausible range for the roll rate (φ̇) based on this straight line, and f) Checking whether the measured or determined roll rate (φ̇) lies outside or inside the plausible range for the roll rate (φ̇).

[0013] Preferably, the plausible range for the roll rate φ̇ can include a tolerance band with the straight line, in particular as its center line. Additionally, the plausible range for the roll rate φ̇ can include an extended range that stretches from the value of zero for the roll rate φ̇ up to the tolerance band.

[0014] If, in this embodiment of the method, it is determined once or several times that a measured or determined roll rate φ̇ lies outside or not within the plausible range for the roll rate φ̇, then an implausible signal can be generated, which evaluates the measured or determined roll rate φ̇ as implausible. Conversely, if it is determined once or several times that the measured or determined roll rate φ̇ lies within the plausible range for the roll rate φ̇, then, for example, no implausible signal is generated, and a plausible value for the measured or determined roll rate φ̇ is assumed.

[0015] According to another aspect, the invention discloses a device for carrying out the above-described method according to claim 5. drawing

[0016] An embodiment of the invention is explained in more detail in the following description with reference to the figures. The figures show: Fig. 1 a perspective view of a vehicle in which a method for verifying the plausibility of a measured rotation rate of the vehicle body is carried out according to a preferred embodiment of the method according to the invention; Fig. 2 a diagram showing a relationship between the roll rate and a lateral jerk of the vehicle. Fig. 1 Fig. 3 represents a flowchart of a preferred embodiment of the method according to the invention; Fig. 4 shows a schematic representation of a preferred embodiment of a device for carrying out the method of Fig. 3 . Description of the exemplary embodiment

[0017] A preferred embodiment of the method according to the invention is based on the physical background explained below. In an earth-fixed coordinate system 10 (X, Y, Z), as it exists in Fig. 1As shown, the acceleration due to gravity, g, acts in the direction of the Earth's center, i.e., in the direction of the vertical axis Z. If, for example, a vehicle body 2 of a vehicle 1 is rotated relative to the Earth-fixed coordinate system 10 (X, Y, Z) about the longitudinal axis (x-axis) and / or the transverse axis (y-axis) of a vehicle-fixed coordinate system 10' (x, y, z) of the vehicle 1, the magnitude of the acceleration due to gravity, g, measured proportionally along these axes changes. Thus, if the rotation of the vehicle body 2 changes, the measured accelerations also change. The cause of the change in rotation is irrelevant. Possible causes include, for example, a change in the inclination of the ground or a change in the angles of the vehicle body 2 relative to the chassis 3 of the vehicle 1, for example by initiating braking of the vehicle 1, whereby the vehicle body 2 then rotates around the y-axis of the vehicle-fixed vehicle coordinate system 10' (x, y, z) (pitching).The component of the acceleration due to gravity, g, measured along the longitudinal axis x and / or along the transverse axis y of vehicle 1 can be determined from trigonometric relationships. Since the expected maximum rotations of the vehicle body 2 are in a small range (< 20°), the trigonometric functions can be approximated as linear using small-angle approximation. Thus, the measured components are given by... axe and ay The following relationships exist for the acceleration due to gravity g in the x and y directions of the vehicle-fixed vehicle coordinate system 10' (x, y, z): a x = − g ⋅ θ a y = g ⋅ φ where g: acceleration due to gravity i : Nickwinkel des Fahrzeugaufbaus gegenben dem erdfesten Koordinatensystem 10 (nach DIN ISO 8855) f : Rollwinkel des Fahrzeugaufbaus gegenben dem erdfesten Koordinatensystem 10 (nach DIN ISO 8855) are.

[0018] The rotation rates the and ḟ can be determined through analytical differentiation: a ˙ x = − g ⋅ θ ˙ ↔ θ ˙ = − a ˙ x / g a ˙ y = g ⋅ φ ˙ ↔ φ ˙ = a ˙ y / g

[0019] The relationship between rotation rates the and ḟand the changes in acceleration, i.e., the respective jerk jx and you in the x and y directions jx = a ˙ x jy = a ˙ y is therefore linear, where the linear dependence is defined by a straight line whose slope is 1 / g or -1 / g amounts.

[0020] The jerk jx or you is the instantaneous rate of change of acceleration over time axe or ayof vehicle 1 in the x- and y-directions. The SI unit of jerk is m / s³. Formally, jerk is the derivative of acceleration with respect to time, i.e., the second time derivative of velocity and the third time derivative of displacement. If, as here, a vehicle-fixed coordinate system 10' (x, y, z) is assumed, the jerk can be determined separately for each coordinate direction, here in particular as longitudinal jerk ax or lateral jerk ay, or more generally vectorially as the derivative of the acceleration a with respect to this vehicle-fixed coordinate system 10' (x, y, z).

[0021] A rotation rate the or ḟ Therefore, anything other than zero always results in a corresponding jerk jx = äx or jy = äy as the cause. A rotation rate the or ḟ non-zero during a jerk jx = äxor jy = ȧy equals zero or with a jerk that is too small in magnitude jx = äx or jy = ȧy is not plausible and therefore indicates a faulty sensor signal.

[0022] In addition to gravitational acceleration, the sensors also detect, for example, linear accelerations caused by vehicle dynamics. These occur, for instance, when cornering in the lateral direction y and when braking the vehicle 1 in the longitudinal direction x. These vehicle dynamics-induced linear accelerations generally lead to a rotation of the vehicle body 2 relative to the chassis 3. This rotation is limited by the vehicle's structure and also influenced by the dampers. Therefore, it is possible, for example, that the jerk jx = äx or jy = äy increases while the yaw rate yaw rate the or ḟ remains constant.

[0023] The previously described relationships between the jerk jx = ȧ x or jy = äy and the rotation rate θ̇ (Nickrate) or φ̇ (Rollrate)allow for a plausible range 4 for the rotation rate the or ḟ depending on the jerk jx = ȧ x (longitudinal jerk) or jy = äy (transverse jerk) to be defined. This plausible range is in Fig. 2 represented in relation to a straight line, which shows the linear relationship between the roll rate according to equation (4) above. ḟ (in rad / s) and the transverse jerk jy = äy (in m / s 3< ). This relationship forms a straight line 5 with a slope of 1 / g according to the above equation (4) and represents the expected relationship between the roll rate ḟ (in rad / s) and the lateral jerk jy = äy (in m / s²) without taking into account linear accelerations caused by vehicle dynamics. If, for example, the rotation of the vehicle body 2 relative to the chassis 3 changes while stationary due to a change in load, the expected roll rate will change. ḟ exactly on straight line 5.

[0024] The in Fig. 2 The grey shaded area represents the plausible range 4 for the roll rate. ḟ preferably, the plausible range for the roll rate includes 4. ḟ A tolerance band 6 with the straight line 5 as its center line. Additionally, the plausible range 4 for the roll rate can be defined. ḟ comprise an extended area 7, which extends from the value zero for the roll rate φ̇ to the tolerance band 6 and essentially forms two triangular areas, one of which is located on this side and the other on the other side of the tolerance band 6.

[0025] The plausible range for the nick rate the can then be determined analogously on the basis of a straight line which, according to the above equation (3), represents the linear relationship between the longitudinal jerk jx = ȧ x and the nick rate the represents, whereby the slope of the line then has a negative sign according to the equation (3) above.

[0026] Since both the roll rate ḟ as well as the nick rate the Each representing a rotation rate, the terms "roll rate" will be used in the following description of a preferred embodiment of the method as a replacement for the terms "roll rate". ḟ " and "Nickrate the The term "rotation rate" is used.

[0027] A device for carrying out the method according to the invention comprises, in accordance with Fig. 4For example, a sensor device 8 with an acceleration sensor and a gyroscope, and a computing and evaluation device 9 in which a program is implemented by which the method is realized. The computing and evaluation device comprises, in particular, at least one microprocessor and a memory. The sensor device, for example, feeds acceleration signals representing the acceleration and gyroscope signals representing the gyroscope rate into the computing and evaluation device, where they are then evaluated in accordance with the method according to the invention.

[0028] This program will be described below using the example in Fig. 3 described in the illustrated schedule.

[0029] In step 100, for example, the rotation rate of the vehicle body 2 of the vehicle 1 is measured using the rotation rate sensor of the sensor device 8, with reference to Fig. 2 for example the roll rate ḟ. Alternatively, the rotation rate can also be derived from another quantity measured by a sensor.

[0030] In step 200, the acceleration a of the vehicle is then measured using the acceleration sensor of the sensor device 8, or determined in the computing and evaluation unit from another quantity that affects the vehicle structure 2 in the same direction with respect to the rotation rate, with reference to Fig. 2 for example, the lateral acceleration ay.

[0031] In step 300, the calculation and evaluation unit then calculates the time-dependent acceleration change ȧ or the jerk j as the time derivative of the acceleration a from the measured or determined acceleration. From the acceleration change ȧ or the jerk j, the calculation and evaluation unit then determines, in step 400, the straight line 5 and, based on this straight line 5, the plausible range 4 for the rotation rate, specifically for the roll rate. ḟ .

[0032] In step 500, the processing and evaluation unit 9 then checks whether the measured or determined rotation rate lies outside or within the plausible range 4. This can be achieved, for example, by updating a running counter, which preferably starts at zero, by a count value, e.g., "0 + 1", if the measured or determined rotation rate, in particular the roll rate, is outside the plausible range 4. ḟ...is outside or not within the plausible range 4. If this updated counter "1" then exceeds a threshold, e.g., threshold "2", this means that the measured or determined rotation rate, in particular the roll rate, is incorrect. ḟ several times it was outside the plausible range 4.

[0033] Then, in the calculation and evaluation unit 9, an implausible signal is generated in a step of 600, which represents the (last) measured or determined rotation rate, in particular the measured or determined roll rate. ḟ assessed as implausible. Therefore, preferably, the calculation and evaluation unit 9 must have repeatedly determined in step 600 that a measured or determined rotation rate, in particular the measured or determined roll rate, is correct. ḟThe implausible signal is generated if the measured or determined rotation rate, in particular the measured or determined roll rate, is outside the respective plausible range 4 before the implausible signal is generated. Alternatively, it can also be provided that if, in step 500, the measured or determined rotation rate, in particular the measured or determined roll rate, ḟ The implausible signal is generated by the computing and evaluation unit 9 only once if the value is outside or not within the plausible range.

[0034] Otherwise, i.e., if the calculation and evaluation unit has determined in step 500 that the measured or determined rotation rate, in particular the measured or determined roll rate, is incorrect. ḟ If the value lies or has lain once or several times within or not outside the plausible range 4, then the computing and evaluation unit 9 does not generate an implausible signal and then, in a step 700, the measured or determined rotation rate, in particular the measured or determined roll rate, is calculated. ḟFor example, it can be used as an input variable for a vehicle dynamics control system. This can be done by the processing and evaluation unit 9 then using the measured or determined yaw rate, in particular the measured or determined roll rate. ḟ into the vehicle dynamics control system.

[0035] In general, the proposed method therefore starts, for example, with a measurement of the rotation rates of the vehicle body 2 about at least two mutually perpendicular axes, here, for example, about the x-axis (longitudinal axis of the vehicle 1) and the y-axis (transverse axis of the vehicle 2) in the vehicle-fixed coordinate system 10'. The plane that these axes together span is preferably parallel to a plane spanned by the longitudinal axis x and the transverse axis y of the vehicle-fixed coordinate system 10'. Furthermore, the relative rotation of the vehicle-fixed coordinate system 10' with respect to the Earth-fixed coordinate system 10 must preferably be known or determined so that the measured rotation rates can be converted into a rotation rate about the longitudinal axis x and a rotation rate about the transverse axis y of the vehicle.

[0036] For example, another requirement is the measurement of the accelerations a of the vehicle body 2, also in at least two mutually perpendicular axes. The measured accelerations must preferably be convertible, analogous to the rotation rates, into an acceleration ax in the direction of the longitudinal axis x and into an acceleration ay in the direction of the transverse axis y of the vehicle 1. REFERENCE MARK LIST

[0037] 1 Vehicle 2 Vehicle body 3 Chassis 4 Plausible range 5 Straight line 6 Tolerance band 7 Extended range 8 Sensor device 9 Computing and evaluation device 10 Earth-fixed coordinate system 10' Vehicle-fixed coordinate system g Acceleration due to gravity i Pitching angle f roll angle the Nickrate ḟ Roll rate axe Longitudinal acceleration ay Lateral acceleration ȧ x, jx Longitudinal acceleration change / longitudinal jerk ȧy, jy Lateral acceleration change / lateral jerk

Claims

1. A computer-implemented method for checking the plausibility of a measured or determined roll rate (φ̇) of a vehicle body (2) of a vehicle (1) about a longitudinal axis (x) of the vehicle (1), wherein the method comprises the following steps: a) measuring or determining (100) the roll rate (φ̇) of the vehicle body (2), b) measuring or determining (200) a lateral acceleration (ay) in the lateral direction (y) of the vehicle (1) in a vehicle-fixed coordinate system (10'), characterized by c) calculating (300) a change in lateral acceleration (ȧy) or a lateral jerk (jy) as the time derivative of the lateral acceleration (ay), and d) determining (400) a straight line (5) with a gradient 1 / g, where g is gravitational acceleration, and wherein the straight line (5) represents a linear dependency between the roll rate (φ̇) and the change in lateral acceleration (ȧy) or the lateral jerk (jy), and e) determining (400) the plausible range (4) for the roll rate (φ̇) on the basis of this straight line (5), and f) checking (500) whether the measured or determined roll rate (φ̇) lies outside or within the plausible range for the roll rate (φ̇).

2. The method as claimed in claim 1, characterized in that the plausible range (4) for the roll rate (φ̇) comprises a tolerance band (6) with the straight line (5), in particular as the centerline.

3. The method as claimed in claim 2, characterized in that the plausible range (4) for the roll rate (φ̇) comprises at least one extended range (7) that extends from the value zero for the roll rate (φ̇) to the tolerance band (6).

4. The method as claimed in any one of the preceding claims, characterized in that a) if it has been determined once or repeatedly that a or the measured or determined roll rate (φ̇) is outside or not within the plausible range (4) for the roll rate (φ̇) then a Not-Plausible signal is generated that assesses the measured or determined roll rate (φ̇) as not plausible, and b) if it has been determined once or repeatedly that a or the measured or determined roll rate (φ̇) is within the plausible range for the roll rate (φ̇), then no Not-Plausible signal is generated and a plausible value for the measured or determined roll rate (φ̇) is assumed.

5. A device for carrying out the method as claimed in any one of the preceding claims, comprising at least: a) a sensor apparatus having at least one acceleration sensor and at least one rotation rate sensor, b) a computing and evaluation apparatus that processes acceleration signals from the at least one acceleration sensor and the at least one rotation rate sensor according to the method.