A method for determining at least one integrity piece of information regarding the positioning result of a vehicle's GNSS-based positioning device when GNSS reception conditions change suddenly and significantly.

Abstract

To provide a method for determining at least one piece of integrity information about a localization result of a GNSS-based localization device (2) of a vehicle (1) in the case of a sudden and remarkable change in GNSS reception condition.SOLUTION: A method includes at least a step a) of using a GNSS-based localization device (2) to specify a present self position of a vehicle (1), a step b) of determining at least one piece of integrity information about the self position specified in the step a) by using the GNSS-based localization device (2), a step c) of identifying a GNSS reception condition which has suddenly and remarkably changed or is remarkably changed, and a step d) of adapting the step of determining at least one piece of integrity information to the GNSS reception condition which has changed or is changed.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for determining at least one piece of integrity information related to a positioning result of a GNSS-based positioning apparatus for a vehicle when GNSS reception conditions change suddenly and significantly. Furthermore, a computer program for carrying out the method, a machine-readable storage medium, and a correspondingly configured positioning apparatus for a vehicle are provided. The present invention is particularly usable in GNSS-based positioning systems for autonomous driving or semi-autonomous driving.

Background Art

[0002] Prior Art Using the Global Navigation Satellite System (GNSS), it is possible to achieve geospatial positioning at substantially any location on the Earth. GNSS satellites orbit the Earth and transmit encoded signals. Using these signals, a GNSS receiver calculates the distance or range from the receiver to the satellite by estimating the time difference between the time the signal is received and the transmission time. If a sufficient number of satellites (typically six or more) are being tracked, the estimated distances to the satellites can be converted into an estimation of the receiver's position. Currently, there are more than 130 GNSS satellites orbiting the Earth, which means that normally up to 65 of these satellites are visible above the local horizontal plane at any given time.

[0003] When discussing the performance of GNSS / INS (Global Navigation Satellite System) positioning sensors, the integrity criterion is usually mentioned in addition to the three criteria of accuracy, continuity, and availability. Integrity is generally defined as a measure of confidence that can be placed on the accuracy of the information provided by a GNSS or GNSS / INS system. Approaches to determining integrity that have been studied to date are substantially based on the current variance and / or standard deviation of the parameter estimates of the positioning solution. However, this approach, being primarily mathematical, may have the drawback of not being able to adequately account for changes in external influences, and thus may determine integrity values ​​that do not adequately reflect the actual situation, at least temporarily, and in the worst case, integrity values ​​that are too high. In this regard, this specification focuses particularly on further improving the positioning solutions on which integrity determination is performed. [Overview of the project] [Means for solving the problem]

[0004] Disclosure of the invention In this specification, according to claim 1, a method for determining at least one integrity piece of information relating to the positioning result of a vehicle's (at least similarly) GNSS-based positioning device in the event of a sudden and significant change in GNSS reception conditions, a) A step of determining the vehicle's current position using a GNSS-based positioning device, b) A step of determining at least one integrity piece of information relating to the self-position identified in step a) using a GNSS-based positioning device, c) A step of identifying a GNSS reception status that has changed suddenly and significantly or has been significantly altered, d) A step of adapting the step of determining at least one integrity piece of information to changed or altered GNSS reception conditions, A method is proposed that includes at least the following.

[0005] Steps a), b), c), and d) can be carried out, for example, at least once and / or repeatedly, in the order presented, in order to implement the method. Furthermore, steps a), b), c), and d), in particular steps a) and b), and possibly c), can be carried out at least partially in parallel or simultaneously.

[0006] This method can contribute to determining at least one piece of integrity information, such as a so-called protection level, during phases in which GNSS-based positioning (purely or primarily) is impossible, particularly during dead reckoning (so-called non-celestial positioning methods (dead reckoning, abbreviated as DR). Dead reckoning is particularly relevant to phases or operating modes in which positioning equipment is using inertial positioning methods, such as inertial navigation. This is possible when GNSS reception is obstructed or severely limited, as can be observed, for example, in valleys between buildings or roads, next to trucks, and / or inside tunnels.

[0007] The positioning device (positioning sensor) may be, for example, a combined GNSS-INS sensor, or the positioning device may include such a sensor. In this context, INS stands for Inertial Navigation System. Therefore, the positioning device can be configured to perform vehicle positioning based on at least GNSS measurements. Preferably, the positioning device can also be configured to perform vehicle positioning based on GNSS measurements and inertial measurements, and / or in combination with or fused with vehicle sensor data such as ambient sensor data. Examples of vehicle sensors include steering angle sensors and / or wheel speed sensors. Examples of ambient sensors include cameras, radar sensors, lidar sensors, and / or ultrasonic sensors. Furthermore, map data from digital maps and / or messages from other vehicles can be used during positioning.

[0008] In step a), a step is performed to determine the vehicle's current position using a GNSS-based positioning device. The positioning device can perform positioning based on a combination (hybrid) GNSS and INS. If GNSS-based positioning is temporarily unavailable, INS-based positioning can be used in step a). The positioning device can perform at least one parameter estimation for positioning. Parameters that can be estimated include, for example, (self) position, (self) velocity, (self) acceleration, and / or vehicle orientation. In particular, at least the vehicle's (self) position is estimated.

[0009] In step b), a step is performed in which a GNSS-based positioning device is used to determine at least one integrity piece of information regarding the self-position identified in step a). The integrity piece may be, in particular, the integrity range of the parameter estimation (of the at least one parameter mentioned above), which represents the range in which the estimated parameter with the lowest probability lies. In other words, the integrity range represents the range in which the estimated parameter value with the lowest probability actually lies. The estimated parameter (value) essentially represents the (individual, especially current) estimation result of the parameter estimation. This means, in other words, that the integrity range represents the range in which the real or actual value of the estimated parameter with the lowest probability lies. Such an integrity range is sometimes referred to as the "Protection Level".

[0010] The lowest probability is generally a predefined minimum probability. The lowest probability is preferably 90%, particularly preferably 95%, or even 99%.

[0011] The integrity range is preferably the protection level. The protection level generally represents the (spatial, particularly two-dimensional or three-dimensional) range in which the estimated parameter (value) with the lowest probability lies. The estimated parameter (value) essentially represents the (individual, particularly current) estimation result of the parameter estimation. This means, in other words, that the protection level specifically represents the range in which the actual or actual value of the estimated parameter with the lowest probability lies.

[0012] In other words, the level of protection represents, in particular, the confidence interval or (spatial) confidence range in which the true value of the estimated parameter with the lowest probability lies. The parameter estimate is usually located at the center or middle of the confidence interval or confidence range.

[0013] The lowest probability that the estimated parameter's actual or real value actually lies within the protection level is significantly higher than in the case of the "normal" integrity range. The lowest probability here is typically greater than 99.99%, particularly preferably greater than 99.999%, or even greater than 99.9999%. Even in the case of the protection level, the lowest probability cannot be expressed as a percentage, but it can be expressed in the form of a possible error over a given time interval. For example, a protection level can be defined such that the parameter in question falls outside the protection level range at most once every ten years. The protection level can be expressed, for example, as a unitless probability, or as a rate, i.e., an error probability over a given time interval.

[0014] The protection level is a (safety) parameter of the integrity concept used in the context of urban vehicles. The protection level can also be described as a statistical error margin, which is calculated such that the probability of the absolute position error exceeding the alarm limit is below the target risk for integrity. Similar to the definition of the alarm limit, the protection level can usually be defined separately for the horizontal plane (Horizontal Protection Level, HPL) and the vertical direction (Vertical Protection Level, VPL). This specification particularly focuses on the horizontal dimension, which is defined as the horizontal protection level having the radius of a circle or (more generally) the semi-axes of an ellipse in the horizontal plane (the local plane tangent to the WGS-84 ellipsoid), with its center at the true position representing the range where compliance with the specified horizontal position is guaranteed. This is the horizontal range that satisfies the requirements for identifying malfunction and false alarm of the selected satellite set, especially when autonomous error detection is used. Generally, the alarm limit is defined by the application, and the protection level is calculated by the positioning device. Since the position error cannot be observed, alarm determination can be implemented by comparing the specified alarm limit (AL) with the calculated protection level (PL), in particular, an alarm can be triggered when PL>AL. In contrast, when PL<AL, the alarm is usually not triggered.

[0015] Step c) involves identifying GNSS reception conditions that have changed or been altered suddenly and significantly. GNSS reception conditions are characterized in particular by the number and / or constellation of GNSS satellites that can be received (without interference and / or reflection). This usually relates to GNSS satellites that can be received by the vehicle or the vehicle's GNSS antenna. “Sudden” as used herein is understood, in other words, to be a sudden change, for example, a change occurring over a period of 60 seconds or less, preferably over a period of 30 seconds or less, and most preferably over a period of 15 seconds or less. “Significant” as used herein is understood, in other words, to be a change of particular significance, for example, a change of at least 50%, preferably at least 70%, and most preferably at least 90% of the GNSS reception conditions. For example, a significant decrease in GNSS reception conditions may be observed upon entering a tunnel. The number of receivable GNSS satellites generally decreases suddenly by at least 90% or even 100%. For example, a significant increase in GNSS reception conditions may be observed upon exiting a tunnel. The number of receivable GNSS satellites generally increases suddenly. For example, a significant change in GNSS reception conditions can be observed while traveling through a tunnel. Tunnels are selected as an example of areas with significant GNSS shielding. As a comparative index, normal GNSS reception in unobstructed space is used in particular.

[0016] In step d), a step is performed to adapt the determination of at least one integrity information to the changed or altered GNSS reception conditions. For the adaptation, in particular, artificial intervention is performed in the calculation of the integrity information, which is mathematically defined by other means. In the case of normal (uninterrupted) GNSS reception conditions, the integrity information can be determined, for example, based on at least one variance and / or standard deviation of the self-position estimate. For this purpose, a localization filter, such as a Kalman filter, can be used. Such a filter generally stores an algorithm that processes GNSS data and / or INS data as input quantities and can output, within the framework of estimation, a localization result and integrity information related to the localization result, such as a variance (or standard deviation) and / or covariance matrix. In this context, the adaptation can be performed, for example, by multiplying the integrity information (variance and / or standard deviation) by a scaling factor and / or adding a surcharge to the integrity information. In the case of changes in reception conditions that are the focus of this specification, typically, values ​​that are too low may be observed with respect to integrity information, particularly the protection level, so subtraction is usually not necessary. This means, in other words, that the scaling factor and / or the markup (value) are generally always positive.

[0017] In a favorable embodiment, it is proposed that the adaptation in step d) be carried out such that changes in integrity information resulting from sudden and significant changes or alterations in GNSS reception conditions are attenuated and / or at least partially modified. "Attenuation" should be understood, in particular, as artificially canceling out excessively strong deviations downward.

[0018] In a further advantageous embodiment, it is proposed that the fitting in step d) be carried out such that the integrity information is scaled by a (positive) scaling factor and / or a calculated first (positive) surcharge is applied to the integrity information while GNSS reception is suddenly and significantly reduced. In this context, scaling by the scaling factor and / or application of the calculated first surcharge can be carried out over a first predefinable period (i.e., during a first predefinable period). The first period can be selected, for example, according to the normal transition time when entering a tunnel.

[0019] In a further advantageous embodiment, it is proposed that the conformance in step d) be carried out such that the calculated second (positive) surcharge is applied to the integrity information while GNSS reception is significantly reduced. The second period is not typically assumed, but it is also conceivable that the second surcharge be applied over a second period.

[0020] In a further advantageous embodiment, it is proposed that the fitting in step d) be carried out such that the calculated third (positive) surcharge is applied to the integrity information while GNSS reception is suddenly and significantly increasing. In this regard, the application of the calculated third surcharge can be carried out over a predefined third period (i.e., during a predefined third period). The third period can be selected, for example, according to the normal transition time when exiting a tunnel.

[0021] In a further embodiment, a computer program for carrying out the method disclosed herein is proposed. In other words, this relates in particular to a computer program (product) that, when executed by a computer, includes instructions for causing a computer to carry out the method disclosed herein.

[0022] According to a further aspect, there is proposed a machine-readable storage medium in which the computer program disclosed herein is stored or retained. Basically, the machine-readable storage medium is a computer-readable data carrier.

[0023] According to a further aspect, there is proposed a positioning apparatus for a vehicle, which is configured to carry out the method described herein. The apparatus may for example comprise a computing device and / or a control device (controller) capable of executing instructions for implementing the method. For this purpose, the computing device or the control device can for example execute the specified computer program. For example, the computing device or the control device can access the specified storage medium to enable execution of the computer program. The positioning apparatus can for example be, in particular, a motion sensor and a position sensor arranged in or on the vehicle.

[0024] The details, features and advantageous embodiments discussed in connection with the method can also be correspondingly embodied in the computer program and / or the storage medium and / or the positioning apparatus disclosed herein, and vice versa. To that extent, reference is made in full scope to the description herein for more detailed characterization of the features.

[0025] Hereinafter, the solution disclosed herein and the technical environment thereof will be described in more detail based on the drawings. It should be noted that the present invention is not intended to be limited by the presented embodiments. In particular, unless otherwise explicitly stated, it is also possible to extract partial aspects of the subject matter described in the drawings and combine them with other components and / or knowledge from other drawings and / or the present description. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] [Figure 1] It is a diagram showing an exemplary sequence of the method disclosed herein. [Figure 2]This figure shows an exemplary vehicle location device as described herein. [Modes for carrying out the invention]

[0027] Figure 1 schematically illustrates an exemplary sequence of the method disclosed herein. This method is used to determine at least one integrity piece of information regarding the positioning result of a GNSS-based positioning device 2 of a vehicle 1 when GNSS reception conditions change suddenly and significantly. The order of steps a), b), c), and d) illustrated by blocks 110, 120, 130, and 140 is exemplary, and the method can be carried out by following the illustrated order at least once, for example.

[0028] According to step a) in block 110, a step is performed in which the current self-position of vehicle 1 is determined using the GNSS-based positioning device 2. According to step b) in block 120, a step is performed in which at least one integrity piece of information relating to the self-position determined in step a) is determined using the GNSS-based positioning device 2. According to step c) in block 130, a step is performed in which a GNSS reception condition that has suddenly and significantly changed or been significantly altered is identified. According to step d) in block 140, a step is performed in which the step of determining at least one integrity piece of information is adapted to the changed or altered GNSS reception condition.

[0029] The modifications in step d) can be carried out so that changes in integrity information resulting from sudden and significant changes or alterations in GNSS reception conditions are attenuated and / or at least partially corrected.

[0030] The adaptation in step d) can be carried out so that the integrity information is scaled by a scaling factor and / or a calculated first surcharge is applied to the integrity information while GNSS reception is suddenly and significantly reduced. In this context, scaling by a scaling factor and / or application of a calculated first surcharge can be carried out over a first predefinable period.

[0031] For example, when entering a non-celestial position estimation domain, or immediately after entering a non-celestial position estimation domain, the current protection level (PL), used exemplary as integrity information for a first period, is given by the following formula: PL(t) = s·sigma + b It can be calculated according to [the formula].

[0032] Here, t is the (current) time, s is the first scaling factor, b is the first overlay, and sigma is the (current) standard deviation (or root of variance) of the self-position estimate.

[0033] The first period can be calculated experimentally. For example, in this embodiment, 10 seconds can be used. The first scaling factor can also be calculated experimentally. Sigma is, for example, the estimated (current) standard deviation from the localization filter of the localization device.

[0034] The first surcharge can be used to correct for systematic errors (biases) and can be calculated as follows: If PL_zuletzt - PL_DR > 0, then PL_zuletzt - PL_DR, Otherwise, it is 0 (zero).

[0035] Here, PL_zuletzt is the last protection level value before entering the non-celestial position estimation domain, and PL_DR is the first protection level value after entering the non-celestial position estimation domain.

[0036] The start and end of the non-celestial position estimation domain or non-celestial position estimation (DR) mode can be identified, for example, by the (higher-level) system of the vehicle and / or positioning device, in particular by identifying that the positioning method has been changed and / or that GNSS reception has significantly decreased or increased.

[0037] Furthermore, the adjustment in step d) can be implemented so that the calculated second surcharge is applied to the integrity information while GNSS reception is significantly reduced.

[0038] For example, after entering the non-celestial position estimation domain and after the first period has elapsed, the protection level (PL), which is used exemplary as integrity information, can be calculated according to the following formula. PL(t) = sigma + delta

[0039] Here, delta is the second additional value, delta=PL_DR,a-sigma(a) It can be calculated as follows.

[0040] Here, PL_DR,a is the protection level value at the end of the first period, and sigma(a) is the standard deviation of the estimated position at the end of the first period.

[0041] Furthermore, the adaptation in step d) can be implemented so that the calculated third surcharge is applied to the integrity information while GNSS reception is suddenly and significantly increasing. In this context, the application of the calculated third surcharge can be implemented over a predefined third period.

[0042] For example, when leaving a non-celestial position estimation domain, or immediately after leaving a non-celestial position estimation domain, the (current) protection level (PL), which is used exemplary as integrity information for a third period, can be calculated according to the following formula. PL(t) = sigma + D

[0043] Here, D is the third additional value, D=PL_DR,zuletzt-sigma(t_zuletztDR) It can be calculated as follows.

[0044] Here, PL_DR,zuletzt is the last protection level value within the non-astronomical position estimation domain, t_zuletztDR is the last time within the non-astronomical position estimation domain, and therefore sigma(t_zuletztDR) is the last standard deviation within the non-astronomical position estimation domain.

[0045] Figure 2 schematically shows an exemplary location tracking device 2 in the vehicle 1 described herein. The location tracking device 2 is configured to carry out the method described herein. In this embodiment, the location tracking device 2 is, for example, a GNSS-INS location tracking device.

[0046] When using GNSS-INS positioning equipment for positioning, the number of available GNSS signals is often reduced or lost due to surrounding obstacles or driving through tunnels. This situation is usually referred to as the non-celestial position estimation (DR) mode. Therefore, to calculate integrity information, such as the protection level (PL), it is advantageous to use a hybrid approach that achieves an accurate PL transition when entering DR mode, acquires a highly reliable PL during DR mode, and achieves an accurate transition when exiting DR mode.

[0047] The proposed method can advantageously contribute to a corresponding hybrid approach for maintaining the integrity of GNSS / INS-based positioning sensors in DR mode and / or when GNSS reception suddenly changes from its normal state. In particular, the method can advantageously contribute to preventing the protection level from experiencing meaningless sudden changes even when a sudden change occurs between the DR state and the normal state.

Claims

1. A method for determining at least one integrity piece of information regarding the position determination result of a vehicle (1) based on GNSS (Global Navigation System) (2) in the event of a sudden and significant change in GNSS reception conditions, a) A step of determining the current position of the vehicle (1) using the GNSS-based positioning device (2), b) A step of determining at least one integrity piece of information relating to the self-position identified in step a) using the GNSS-based positioning device (2), c) A step of identifying a GNSS reception status that has changed suddenly and significantly or has been significantly altered, d) The step of determining the at least one integrity information is to adapt it to the changed or altered GNSS reception conditions, It includes at least, The conformity in step d) is, While GNSS reception is significantly decreasing, the calculated second surcharge is applied to the integrity information. The conformity in step d) is, A method in which a calculated third surcharge is applied to the integrity information while GNSS reception is suddenly and significantly increasing.

2. The conformity in step d) is, The changes in integrity information resulting from the sudden and significant changes or alterations in GNSS reception conditions are to be attenuated and / or at least partially modified. The method according to claim 1.

3. The conformity in step d) is, While GNSS reception is suddenly and significantly decreasing, the integrity information is scaled by a scaling factor and / or a calculated first surcharge is applied to the integrity information. The method according to claim 1 or 2.

4. The scaling and / or the application of the calculated first surcharge by the scaling factor is carried out over a first predefinable period. The method according to claim 3.

5. The application of the aforementioned calculated third surcharge is carried out over a predefined third period. The method according to claim 1.

6. A computer program for carrying out the method described in any one of claims 1 to 5.

7. A machine-readable storage medium in which the computer program described in claim 6 is stored.

8. A location-finding device (2) for a vehicle (1), configured to carry out the method described in any one of claims 1 to 5.

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