DE102021202121A1 - Apparatus and method for mapping a vehicle's relative vehicle coordinate system to an absolute global coordinate system - Google Patents

Abstract

The invention relates to a device (1) for mapping a relative vehicle coordinate system (4) of a vehicle (3) onto an absolute global coordinate system, the device (1) having a receiving unit (2) for receiving a location of the vehicle (3) in the absolute global coordinate system by a global position determination system, and wherein the device (1) is designed to generate a global absolute first position for each vehicle's own position using a time stamp using the global position determination system in the global coordinate system, and wherein the relative vehicle coordinate system (4) of the vehicle (3) has an initial vehicle coordinate system origin, which is initialized with an absolute global position of the vehicle (3), and wherein the device (1) is designed to do so when the vehicle (3) is moving, based on a vehicle's own movement and a vehicle direction of the vehicle (3) and the initial vehicle eug coordinate system origin for each vehicle position at the time stamp to determine a global absolute second position in time corresponding to the global absolute first position in the global coordinate system, and wherein the device (1) is designed to map the relative vehicle coordinate system (4) to the global coordinate system minimizing a deviation between the global first position and the global second position. Furthermore, the invention relates to a method and a use

Description

The invention relates to a device for mapping a relative vehicle coordinate system of a vehicle onto an absolute global coordinate system. Furthermore, the invention relates to a method for mapping a relative vehicle coordinate system of a vehicle. Furthermore, the invention relates to the use of the device in a vehicle.

Electronic navigation systems support a driver in guiding his vehicle from a starting point to a destination. The global position of the vehicle is usually determined by a global navigation satellite system (GNSS) and other satellite-based position determination systems and displayed on a road map on a monitor. Such systems have been available and in use for a number of years.

The vehicle is positioned on the road shown schematically using the GNSS data. However, the Global Navigation Satellite System (GNSS) and other satellite-based positioning systems have a typical kilometric error in positioning, ranging from about 5 to 15 meters and up to 30 m in some cases. As such, the level of accuracy for these systems is not as good as most automobile manufacturers would desire to provide a high level of accuracy, for example, as to the vehicle's current location.

The number of lanes on the road to be expected for the respective position is read out, for example, from an additionally used digital navigation map. For this purpose, the digital map includes what are known as map attributes, which provide information about intersections, lane markings, traffic signs, etc.

the DE 10 2018 109 975 A1 discloses a method and system for determining a vehicle position, comprising: receiving, by a processor of a rover vehicle, vehicle position data from one or more parked vehicles; receiving, by the rover vehicle processor, global positioning system data from a GPS receiver of the rover vehicle; and the processor of the rover vehicle processing the vehicle position data and the global positioning system data to determine a position of the rover vehicle.

the DE 10 2016 223 526 A1 discloses a method for determining a first high-precision position of a vehicle, with the steps of: acquiring environmental data values by means of at least one radar sensor of the vehicle, the environmental data values representing an environment of the vehicle; Determining a rough position of the vehicle depending on the detected environmental data values; determining environmental feature data values as a function of the determined rough position of the vehicle, the environmental feature data values representing at least one environmental feature and a second highly accurate position of the at least one environmental feature; and determining the first highly accurate position of the vehicle depending on the at least one environmental feature.

It is therefore an object of the invention to specify a method and a device with which the position of a vehicle in relation to a global coordinate system can be recognized better. Furthermore, it is an object to specify use of the device in a vehicle for detecting a more precise absolute global position of the vehicle in the global coordinate system.

The object is achieved by a device with the features of claim 1 and a method with the features of claim 8. The object is also achieved by use with the features of claim 11. Advantageous developments which can be used individually or in combination with one another , are specified in the dependent claims as well as in the description.

The object is achieved by a device for mapping a relative vehicle coordinate system of a vehicle onto an absolute global coordinate system,
wherein the device has a receiving unit for receiving a location of the vehicle in the absolute global coordinate system by a global positioning system,
and wherein the device is designed to generate a global absolute first position for each vehicle's own position using a time stamp using the global positioning system in the global coordinate system, and wherein the relative vehicle coordinate system of the vehicle has an initial vehicle coordinate system origin which initializes with an absolute global position of the vehicle is,
and wherein the device is designed to calculate a global absolute second position corresponding in time to the global abso to determine the first position in the global coordinate system,
and wherein the device is configured to map the relative vehicle coordinate system to the global coordinate system by minimizing a deviation between the global first position and the global second position.

Mapping is essentially a mapping of the relative vehicle coordinate system to the absolute global coordinate system. The global coordinate system can be understood as the World Geodetic System 1984 (WGS 84), which is a geodetic reference system and provides a uniform basis for position information on earth. In the World Geodetic System 1984 (WGS 84), respective three-dimensional positions of the satellites are specified using Cartesian coordinates (3D rectangular coordinates). The coordinates of the observation stations, in this case the vehicles, whose positions are based on measurements from the satellites, also refer to the same global coordinate system.
The vehicle has its own relative vehicle coordinate system, usually a three-dimensional Cartesian coordinate system, which is fixed to the vehicle.

The vehicle coordinate system origin is initialized with an absolute global position of the vehicle. This initialization can take place, for example, using GNSS data from the global navigation satellite system (GNSS) or using another signal from a global positioning system that supplies a global position at the time of initialization. A new initialization preferably takes place after a predetermined period of time and/or number of kilometers. This has the effect that the deviation (error) between the global absolute first position and the global absolute second position does not become too large.

According to the invention, global absolute first positions are calculated from the GNSS (Global Navigation Satellite System) data in the global coordinate system for each reported vehicle position using the time stamp.

Absolute global second positions, which result from the vehicle's own movement, are calculated for each vehicle's own position using the initial vehicle coordinate system origin and the vehicle orientation.

The current error, i.e. deviation, is calculated from the respective distance between the first positions and the second positions. By minimizing the deviation between the global first position and the global second position (i.e. minimizing the deviation), a mapping of the relative vehicle coordinate system to the global coordinate system can be accomplished. This significantly increases the positioning accuracy of the vehicle. The use of (at least one) first position (points) provided by, for example, the Global Navigation Satellite System (GNSS) and (at least one) second position leads to better position accuracy by creating a mapping between relative vehicle coordinate system and global coordinate system by minimizing a deviation between the global first position and the global second position is performed.

The relatively high inaccuracy of the relative vehicle coordinate system therefore no longer has any influence. The inaccuracy in the vehicle alignment, which is determined using one or a maximum of two points of the vehicle position, is also corrected.

The higher position accuracy made possible by the device leads to better localization of the vehicle in the global coordinate system.
The invention avoids an inaccuracy in the position accuracy, for example due to different tire pressures or other systematic errors.

In a further refinement, the device is designed to generate a plurality of global first positions and a plurality of global second positions which correspond in time to the first global positions.
By using a number of global first positions and a number of corresponding global second positions, an averaging of the error and thus the positioning accuracy can be further increased.

In a further embodiment, the device is designed to carry out the minimization using a least squares error method, a Levenberg-Marquardt method, or a non-linear regression method or a simplex method. This is a method for solving a nonlinear optimization problem. However, assuming that the initial estimate of the vehicle orientation only deviates from the real value by a small angle (< 10°), this can be reduced to a linear optimization problem by small-angle approximation. Therefore, the linear least squares method or, for example, a linear regres sion procedures are used. These can be solved faster.

In a further refinement, the device is designed to assign a weighting to each global first position using an accuracy value transmitted by the global positioning system (GNSS) which belongs to the respective global absolute first position.

In the case of the GNSS data, for example, the accuracy is also transmitted as an estimate of the position in the form of an EPE (estimate of position error), which represents the estimated position error. This corresponds to the probability that the location that the GNSS data indicates is within the "accuracy distance" of the actual location.

Furthermore, in one embodiment, the device is designed to weight global first positions as a function of the accuracy value, i.e. to weight them all the more if the accuracy value is very high. As a result, a higher positional accuracy can be achieved. By using the accuracy of the absolute global first positions, those global absolute first positions with high accuracy can be weighted more heavily in the minimization.

• - Variation des Fahrzeugkoordinatensystemursprungs des relativen Fahrzeugkoordinatensystems,
• - Variation einer Ausrichtung des relativen Fahrzeugkoordinatensystems,
• - Variation einer Skalierung des relativen Fahrzeugkoordinatensystems.

In a further refinement, the device is designed to carry out the minimization by varying a parameter from the following group:

• - variation of the vehicle coordinate system origin of the relative vehicle coordinate system,
• - variation of an orientation of the relative vehicle coordinate system,
• - Variation of a scaling of the relative vehicle coordinate system.

Adjusting the scaling eliminates systematic errors, such as those that occur due to a change in tire pressure. By adapting the position of the relative vehicle coordinate system, improved mapping and thus greater global positioning accuracy can be achieved. Ultimately, this leads to better localization of the vehicle.

In a further development, all parameters from the group are minimized.

The origin, the orientation and the scaling of the relative vehicle coordinate system is thus determined via the optimization/minimization of the distances between global first positions and from the global second positions calculated by the vehicle's own movement.

The higher positioning accuracy ultimately leads to better localization of the vehicle.

In another embodiment, the global coordinate system is the World Geodetic System 1984 (WGS 84). The World Geodetic System 1984 is a geodetic reference system that represents a uniform basis for position information on earth and which is currently the most common global reference system.

• - empfangen eines Standorts des Fahrzeugs in dem absoluten globalen Koordinatensystem anhand eines globalen Positionsbestimmungssystems durch eine Empfangseinheit und generieren für jede Fahrzeugeigenposition anhand eines Zeitstempels eine globale absolute erste Position mittels des globalen Positionsbestimmungssystems im globalen Koordinatensystem,
• - bestimmen bei Fahrt des Fahrzeugs anhand einer Fahrzeugeigenbewegung und einer Fahrzeugrichtung des Fahrzeugs und des initialen Fahrzeugkoordinatensystemursprungs für jede Fahrzeugeigenposition bei dem Zeitstempel die globale absolute zweite Position zeitlich korrespondierend zu der globalen absoluten ersten Position im globalen Koordinatensystem,
• - abbilden des relativen Fahrzeugkoordinatensystems auf das globale Koordinatensystem durch Minimierung einer Abweichung zwischen der globalen ersten Position und der globalen zweiten Position.

Furthermore, the object is achieved by a method for mapping a relative vehicle coordinate system of a vehicle onto an absolute global coordinate system, the relative vehicle coordinate system having an initial vehicle coordinate system origin which is initialized with an absolute global position of the vehicle, comprising the steps:

• - receiving a location of the vehicle in the absolute global coordinate system using a global positioning system by a receiving unit and generating a global absolute first position using the global positioning system in the global coordinate system for each vehicle's own position using a time stamp,
• - determine when the vehicle is moving based on a vehicle's own movement and a vehicle direction of the vehicle and the initial vehicle coordinate system origin for each vehicle's own position in the time stamp, the global absolute second position corresponding in time to the global absolute first position in the global coordinate system,
• - mapping the relative vehicle coordinate system to the global coordinate system by minimizing a deviation between the global first position and the global second position.

The advantages of the device can also be transferred to the method.

• - Variation des Fahrzeugkoordinatensystemursprungs des relativen Fahrzeugkoordinatensystems,
• - Variation einer Ausrichtung des relativen Fahrzeugkoordinatensystems,
• - Variation einer Skalierung des relativen Fahrzeugkoordinatensystems.

In a further embodiment, minimization is carried out by varying a parameter from the following group:

• - variation of the vehicle coordinate system origin of the relative vehicle coordinate system,
• - variation of an orientation of the relative vehicle coordinate system,
• - Variation of a scaling of the relative vehicle coordinate system.

Furthermore, there are a number of global first positions and a number of global second positions corresponding in time to the global first positions. In this case, each first position is assigned a weighting based on an accuracy value transmitted by the global positioning system (GNSS) for each global absolute first position.

Furthermore, the object is achieved by using the device as described above in a vehicle for detecting an exact absolute global position of the vehicle in the global coordinate system.

In a further embodiment, the vehicle has a camera for detecting traffic signs, the device being designed to use the absolute position of the vehicle determined by the device to determine the absolute global position of the detected traffic signs. Vehicles use a camera to recognize traffic signs and calculate their position relative to the vehicle or the camera. The global position of the traffic signs can now be recognized by a more precisely recognized global position.

• 1: ein Fahrzeug mit einer erfindungsgemäßen Vorrichtung,
• 2: eine Verwendung der Vorrichtung zum Erkennen der globalen Position von Verkehrsschildern.

Further features, properties and advantages of the present invention result from the following description with reference to the enclosed figures. It shows schematically:

• 1 : a vehicle with a device according to the invention,
• 2 : a use of the device for recognizing the global position of traffic signs.

1 shows a vehicle 3 with a device 1 according to the invention. The device 1 according to the invention has a receiving unit 2 .

The receiving unit 2 is designed to receive radio waves, which are transmitted from a global positioning system, for example from a global navigation satellite system (GNSS) 5 with a global coordinate system, in order to detect a current location of the vehicle 3 .

The global navigation satellite system (GNSS) 5 uses GNSS satellites which transmit radio waves including GNSS data (GNSS signal) indicating the current positions of the satellites (so-called ephemeris data). The radio waves transmitted from the GNSS satellites are used by the vehicle 3 to identify the current global position in a global coordinate system. The GNSS satellites correspond to positioning satellites. Furthermore, the accuracy of the transmitted position is transmitted with each GNSS signal in the form of an EPE (estimate of position error) value, which represents the estimated position error. This corresponds to the probability that the location that the GNSS data indicates is within the "accuracy distance" of the actual location.

The receiving unit 3 can be designed as an antenna.
The device 1 uses a number of time stamps to generate corresponding global absolute first positions for each vehicle's own position, also referred to simply as global first positions.

Furthermore, the vehicle 3 has its own fixed vehicle coordinate system 4 . This can also be in the form of a Cartesian coordinate system.

The vehicle coordinate system 4 has an initial vehicle coordinate system origin, which is initialized with an absolute global position of the vehicle 3 . This initialization can take place, for example, using GNSS data from the global navigation satellite system (GNSS) 5 . This provides a global absolute position at the time of initialization. This means that the vehicle coordinate system origin is hard-wired/connected to a global position. A new initialization preferably takes place after a predetermined period of time and/or number of kilometers. This ensures that the deviation (error) between the vehicle position in the vehicle coordinate system 4 and the vehicle position in the global coordinate system does not become too large, i.e. the initial estimate of the vehicle orientation only deviates by a small angle (<10°) from the real value.

Furthermore, the device 1 is designed to generate corresponding global absolute second positions for each vehicle position in the time stamp when the vehicle 3 is moving based on a vehicle's own movement of the vehicle 3 and the vehicle direction of the vehicle 3, taking into account the initial vehicle coordinate system origin. These correspond in time to the global absolute first positions in the global coordinate system.

Furthermore, a weight is preferably assigned to each global first position. This depends on the EPE (estimate of position error), ie the estimated position error and thus gives an accuracy value. The more precise the accuracy value is, ie the smaller the estimated position error, the higher the respective global first position is weighted.

The current deviation (error) is calculated as the sum of the squares of the distances between the pairs of second positions and the weighted first positions.

• - Variation des Fahrzeugkoordinatensystemursprungs des relativen Fahrzeugkoordinatensystems 4,
• - Variation einer Ausrichtung des relativen Fahrzeugkoordinatensystems 4,
• - Variation einer Skalierung des relativen Fahrzeugkoordinatensystems 4.

This deviation is now minimized by varying the following three parameters:

• - Variation of the vehicle coordinate system origin of the relative vehicle coordinate system 4,
• - Variation of an orientation of the relative vehicle coordinate system 4,
• - Variation of a scaling of the relative vehicle coordinate system 4.

This means that the vehicle coordinate system origin, the orientation and the scaling of the relative vehicle coordinate system 4 of the vehicle 3 are varied by optimizing the distances between absolute first positions calculated by the GNSS data and from the absolute second positions calculated by the vehicle's own movement.

By using several first and second positions, an averaging of the error is achieved, which increases the imaging and thus the positional accuracy. Furthermore, the imaging and thus the positional accuracy is increased by using a weighting of individual first positions that is matched to the accuracy value of the GNSS data. As a result, first positions with higher accuracy have a higher weight in the minimization. Adjusting the scaling also eliminates systematic errors that occur, for example, due to a change in tire pressure.

This is a nonlinear optimization problem.
However, assuming that the initial estimate of the vehicle orientation deviates from the real value by only a small angle (< 10°), this can be reduced to a linear problem by small-angle approximation, which can be solved very easily, for example, by a weighted linear least squares method leaves.

As a result, the relative vehicle coordinate system 4 can be mapped onto the global coordinate system, i.e. it can be imaged, which leads to a higher positional accuracy.

The higher position accuracy leads to better localization of the vehicle 3.

2 shows a use of the device 1 according to the invention in the recognition and localization of traffic signs 7.

Vehicles 3 recognize traffic signs 7 with the aid of a camera 6 and calculate their position relative to the camera 6/vehicle 3. The vehicle 3 usually knows its absolute position from the GNSS data and the vehicle orientation. However, the determination of the vehicle orientation is imprecise, since it is determined using one or a maximum of two points. Furthermore, the accuracy depends very much on the accuracy of a single GNSS measurement at the time of sighting.

The inaccuracy is further increased by the fact that the camera 6 calibrates a conversion of its movement into absolute distances using the distance provided by the vehicle 3 (wheel ticks). If the distance supplied by the vehicle 3 is imprecise, for example due to a change in tire pressure, this also affects the positional accuracy.

This is now avoided by using the device 1 . The mapping and the higher positional accuracy associated with it ultimately leads to better localization of the vehicle 3. An increase in the positional accuracy of traffic signs 7 can thereby be achieved.

The absolute global positions of the traffic signs 7 obtained in this way are consolidated in the backend of the vehicle 3 and made available to vehicles. Among other things, they can use the sign positions to carry out a localization. Furthermore, the exact absolute position of the traffic signs 7 can be entered in maps and thus be made generally available.

Reference List

1.

contraption

2

receiving unit

3

vehicle

4

relative vehicle coordinate system

5

Global Navigation Satellite System (GNSS)

6

camera

7

traffic sign

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited 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.

Patent Literature Cited

• DE 102018109975 A1 [0005]
• DE 102016223526 A1 [0006]

Claims (12)

Device (1) for mapping a relative vehicle coordinate system (4) of a vehicle (3) onto an absolute global coordinate system, the device (1) having a receiving unit (2) for receiving a location of the vehicle (3) in the absolute global coordinate system by a has a global positioning system, and wherein the device (1) is designed to use a time stamp to generate a global absolute first position for each vehicle's own position using the global position determination system in the global coordinate system, and wherein the relative vehicle coordinate system (4) of the vehicle (3) has an initial vehicle coordinate system origin, which is initialized with an absolute global position of the vehicle (3), and wherein the device (1) is designed to do so when the vehicle (3) is moving using a Vehicle own movement and a vehicle direction of the vehicle (3) and the initial vehicle coordinate system origin for each vehicle own position at the time stamp to determine a global absolute second position in time corresponding to the global absolute first position in the global coordinate system, and wherein the device (1) is designed to bring about a mapping of the relative vehicle coordinate system (4) onto the global coordinate system by minimizing a deviation between the global first position and the global second position. Device (1) after claim 1 , characterized in that the device (1) is designed to generate a plurality of global first positions as well as a plurality of global second positions corresponding in time to the first global positions. Device (1) after claim 2 , characterized in that the device (1) is designed to carry out the minimization using a least squares error method, a Levenberg-Marquardt method, or a non-linear regression method or a simplex method. Device (1) after claim 2 or 3 , characterized in that the device (1) is designed to assign a weighting to each first position, based on an accuracy value transmitted by the global positioning system, which belongs to the respective global absolute first position. Device (1) after claim 4 , characterized in that the device (1) is designed to weight global first positions depending on the accuracy value. Device (1) according to one of the preceding claims, characterized in that the device (1) is designed to carry out the minimization by varying a parameter from the following group: - variation of the vehicle coordinate system origin of the relative vehicle coordinate system (4), - variation of an alignment of the relative vehicle coordinate system (4), - variation of a scaling of the relative vehicle coordinate system (4). Device (1) according to one of the preceding claims, characterized in that the global coordinate system is the World Geodetic System 1984 (WGS 84). Method for mapping a relative vehicle coordinate system (4) of a vehicle (3) onto an absolute global coordinate system, the relative vehicle coordinate system having an initial vehicle coordinate system origin which is initialized with an absolute global position of the vehicle (3), comprising the steps: - receiving a location of the vehicle (3) in the absolute global coordinate system using a global positioning system by a receiving unit (2) and generating a global absolute first position for each vehicle's own position using a time stamp using the global positioning system in the global coordinate system, - determine when the vehicle (3) is moving based on a vehicle's own movement and a vehicle direction of the vehicle (3) and the initial vehicle coordinate system origin for each vehicle's own position in the time stamp, the global absolute second position corresponding in time to the global absolute first position in the global coordinate system, - mapping the relative vehicle coordinate system (4) to the global coordinate system by minimizing a deviation between the global first position and the global second position. procedure after claim 8 , characterized in that a minimization is carried out by varying a parameter from the following group: - variation of the vehicle coordinate system origin of the relative vehicle coordinate system (4), - variation of an orientation of the relative vehicle coordinate system (4), - Variation of a scaling of the relative vehicle coordinate system (4). procedure after claim 8 or 9 , characterized in that a plurality of global first positions and a plurality of global second positions corresponding in time to the global first positions are present, and each first position is assigned a weighting based on an accuracy value transmitted by the global positioning system for each global absolute first position. Use of the device (1) according to one of the preceding Claims 1 until 7 in a vehicle, for detecting an accurate absolute global position of the vehicle (3) in the global coordinate system. use after claim 11 , wherein the vehicle (3) has a camera (6) for recognizing traffic signs (7), the device (1) being designed to determine the absolute position of the vehicle (3) by the device (1) in order to determine the absolute to use the global position of the recognized traffic signs (7).

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