WO2021105010A1

WO2021105010A1 - Method and system for assigning coordinates

Info

Publication number: WO2021105010A1
Application number: PCT/EP2020/082800
Authority: WO
Inventors: Gabriel GAESSLER; Tobias DIPPER
Original assignee: Robert Bosch Gmbh
Priority date: 2019-11-25
Filing date: 2020-11-20
Publication date: 2021-06-03
Also published as: DE102019218180A1

Abstract

A method for assigning coordinates to at least one mobile base station is disclosed, wherein at least one stationary marker is used, having the steps of: setting up the base station; determining a relative position between a vehicle and the base station; and calculating the coordinates of the base station on the basis of the relative position between the vehicle and the base station.

Description

Method and system for assigning coordinates

description

The invention relates to a method for assigning coordinates to a base station according to the preamble of claim 1, as well as a system for using this method.

In the case of the autonomous control of vehicles, according to the prior art, coordinates of the vehicle are regularly required.

The document WO 2017/160467 A1 discloses a method according to which correction data from global navigation satellite system (GNSS) receivers are used to determine a precise positioning accuracy of a receiver, for example a navigation system of a vehicle. Correction data is used here, which is transmitted by satellites and which is linked to a large number of calculated correction data.

The document WO 2017/180430 A1 shows a method whereby a fixed GNSS reference station in connection with a base station assigns the satellite data of a GNSS satellite to a position of the base station with precise location. The precisely determined location of the base station is transmitted to a vehicle that can orient itself on the position of the base station.

A disadvantage of such methods and systems is that GNSS systems generally only have a limited accuracy. This is significantly influenced by atmospheric disturbances. In principle, the radio signals from the satellites do not move exactly as predicted by a simplified model that calculates the radio signals. Constant changes in the atmosphere have a noticeable impact on the radio signals from the satellites. In the above-mentioned methods, an attempt is made to minimize these disturbances with calculations and correction data.

From the manual "etieve JV AG Software Technology Jung - Earthworks Surveying with GPS Measuring Device Magellan Promark 3" it is known to set up a base station at a fixed point, with the base station continuously providing data during a measurement records. A second device called a rover is carried manually and step by step to points to be measured.

The disadvantage of this method is that the calibration of the base station involves a great deal of expenditure in terms of time and design. In addition to the construction steps that must be carefully observed, the time required for calibration is comparatively high, the base station requires a large number of satellite contacts and must not lose them during the subsequent measurements. Particular precision must also be taken into account when initializing the rover, which in turn means a delay in commissioning the entire system.

In contrast, the invention is based on the object of creating a method and a system with which the assignment of coordinates to a base station can take place within a short period of time and these assigned coordinates enable high repeatability of routes of a vehicle called paths.

This object is achieved by a method with the features of claim 1 and by a system with the features of claim 11.

The method according to the invention for assigning geographic, preferably global coordinates to a base station, with the determined coordinates being used to control an autonomous vehicle, in particular, is composed of the following steps:

At a known, fixed point, at least one marker, preferably several markers spaced apart from one another, which can preferably be located at the beginning and at the end of a route to be covered, hereinafter referred to as a path, is set up or selected. This setting up can also be referred to as setting. Such a marker can be, for example, a peg, or some other device that can be fixedly connected to a subsurface. Furthermore, a marker can also be a stationary, already existing marking, such as a milestone, a landmark, a power pole or the like.

It is basically sufficient if a marker is used. A further and / or further marker are not a mandatory requirement for the functionality of the method. In particular, the markers do not have to be on the vehicle's path. Furthermore, in particular afterwards, the base station is set up.

The following “middle three steps” can be carried out in a different order and / or in parallel with one another.

The marker is preferably detected by the vehicle.

A relative position between the marker and the vehicle is particularly preferably determined.

A relative position between the vehicle and the base station is determined according to the invention.

After these three steps, coordinates of the base station are calculated, preferably based on the relative positions from the vehicle to the marker and, according to the invention, from the base station to the vehicle.

The method according to the invention is used to initialize a system with which an autonomous vehicle can then be positioned.

The coordinates assigned according to the above method enable a very high repeatability of the vehicle along the defined path. In this way, the object set out at the beginning is achieved and the disadvantages known from the prior art are overcome.

Recalculating the coordinates of the base station based on the “middle three steps” mentioned above is particularly helpful and necessary if the base station has been moved. That is, these steps are preferably repeated cyclically when the base station is re-established.

Further advantageous embodiments of the invention are described in the dependent claims.

The at least one marker, but in particular each marker, preferably has an individual marking which enables the marker to be unambiguously identified. Such a marking can be, for example, a QR code or a barcode or a similar, automatically detectable sign. A digital feature such as an RFID chip or the like would also be conceivable.

It is particularly preferred if the calculated coordinates are assigned to the base station. The location of the base station is known and determined.

After the coordinates have been assigned to the base station, the vehicle can advantageously be controlled using the data from the base station, in particular along defined paths.

In a further exemplary embodiment, the relative position between the vehicle and the marker is determined in that a suitable device on the vehicle detects the marker.

In an advantageous embodiment, the device for detecting the marker is a camera. This is designed in such a way that, as soon as a marker is in the field of view of the camera, it takes pictures in order to detect the marker. A vector results from the already determined relative positions.

Depending on the design, it can be advantageous if the vector between the vehicle and the marker is known at the time of detection. For this purpose, in addition to a suitable device for detecting the marker, a distance measuring device can be provided on the vehicle, or the detection can only take place when the marker is in the detection area of the device and / or the distance measuring device.

In a preferred development, an autonomous field robot is used as the vehicle.

If the base station is set up at its place of use, it is advantageously measured using a GNSS system. The calibration takes place in a very short period of time, since an exact position with correct, i.e. error-free, coordinates is not necessary. The assignment of the coordinates, which serve as the basis for the system or the base station to supply the vehicle with coordinates so that it can move along certain paths, is carried out by calculating the relative positions and assigning the coordinates calculated from them to the base station. These assigned coordinates are also known as global coordinates. A dependency between a more exact GNSS-determined position of the There is therefore no base station and high repeatability of the vehicle's routes.

A system according to the invention is used to apply a method described above and has at least one mobile base station and at least one vehicle. Both the base station and the vehicle each have at least one transmitter and one receiver, so that data can be sent and received between the base stations and the vehicle. The connection between the individual transmitters and receivers is preferably wireless, for example via Bluetooth, a WLAN connection, radio or a similar connection that is designed to send data between the participants in almost real time. Furthermore, the system has at least one marker that can be detected by the vehicle. A relative position between the marker detected in this way and the vehicle is known, and a relative position between the vehicle and the base station is also known, so that the relative position between the base station and the stationary marker is also calculated. This calculation of the relative positions is used, starting from the stationary marker, in connection with the so known relative positions of the mobile base station, so that coordinates that are relevant for the system can be assigned. It is not a disadvantage if the previously roughly carried out calibration of the base station via a GNSS system does not match the calculated coordinates.

In a preferred exemplary embodiment, the vehicle is designed to travel specified paths with a high degree of repeatability. These lanes can in particular be defined by a marker at the beginning of the lane and a marker at the end of the lane. The markers can also be independent of the lanes. A marker does not have to be part of a track. Rather, a marker can also be located off a path and recorded there in order to assign its coordinates to the base station. The path is then identified by a sequence of GNSS coordinates, which, however, do not have to coincide with stationary markers. Data transmitted from the base station are used to determine the exact position data on the basis of which the vehicle can be controlled. Since these coordinates have been assigned as a function of the relative positions between the vehicle, marker and base station, it is not necessary to match these coordinates with more precise GNSS position data. A lengthy calibration of the base station is not necessary and an inaccuracy compared to the more precise GNSS position data has no influence on the repeatability of the vehicle along the path. The method according to the invention and the system according to the invention are preferably used to allow an autonomous field robot to control a field along a plurality of preferably parallel paths.

An embodiment of a method according to the invention and a system according to the invention is shown in the figures.

Show it

Figure 1 is a diagram of a method according to the invention,

Figure 2 shows an embodiment of a system according to the invention, and

FIG. 3 shows a detailed representation of a system according to FIG. 2.

FIG. 1 shows a diagram which shows the sequence of a method according to the invention. In a first step S1, a marker is set or an existing marker is selected. In general, a marker means, for example, an unchangeable landmark, that is to say a surveying point, milestone, power pole or the like. In relation to the following FIG. 2, this means, for example, a peg that is introduced into the subsurface of a field 2 so that it is stationary. This marker has a marking that makes these markers clearly identifiable.

In the following step S2, the marker is detected by a vehicle via this marking. A relative position between the vehicle and the marker is determined in step S3 with an internal or external computing unit. The determination is carried out in such a way that a vector between the vehicle and the marker is known at the time of detection. For example, the vehicle can be positioned directly above the marker so that the vehicle, which is in the same position as the marker, can send the coordinates of the marker to the base station. These coordinates are stored in the system as the fixed point of the marker, so that this unchangeable position, even if the base station has changed, is known.

Using the position known in this way, a relative position between the vehicle and the base station is determined in step S4. From the relative positions determined from steps S3 and S4, global coordinates of the base station can be calculated in step S5. This calculation is also carried out on the internal or external processing unit.

Finally, in step S6, the calculated global coordinates are assigned to the base station. These global coordinates are not necessarily associated with real, exact GNSS Coordinates coincide, but this is irrelevant for the applications described below.

Steps S2 to S6 can be linked to one another repeatedly in real operation, so that the global coordinates assigned to the base station are continuously updated. These steps usually only have to be carried out once when starting the system or when the base station has been set up in a new location. If the location of the base station does not change, the steps do not need to be repeated. This is advantageous with regard to a high repeatability of the vehicle if no local base station is used.

The global coordinates determined with this system are regularly afflicted with an error that originates from an inadequate calibration of the first base station position. However, this error is approximately constant, which means that a high level of repeatability of the travel paths along the paths of the vehicle can be achieved.

FIG. 2 shows an exemplary embodiment of a system 1 according to the invention. According to the present exemplary embodiment, the system is explained using a field 2. A base station 4 is located at one edge of field 2. This base station 4 can be located on field 2 or, as shown here, away from field 2. In addition, only one base station 4 is shown for the sake of simplicity. Depending on the system size and / or other factors, several base stations 4 can also be set up.

Along a longitudinal side of the field 2, markers 6a to 6f are provided at regular or even irregular intervals. Of course, the number of markers 6a to 6f is not limited to the six markers 6a to 6f shown here; rather, fewer as well as far more markers 6a to 6f can be used. In the present exemplary embodiment, a vehicle 8a to 8f is assigned to each marker 6a to 6f. The number of vehicles 8a to 8f is also not limited to the number shown here. A direct dependency between the number of markers 6a to 6f and the number of vehicles 8a to 8f is also not absolutely necessary. It is also practicable for a vehicle 8a to 8f to be assigned to several markers 6a to 6f, or for several vehicles 8a to 8f to be assigned to one marker 6a to 6f.

The vehicles 8a to 8f proceed from the longitudinal side of the field 2, in the exemplary embodiment shown here, perpendicular to this, along tracks 10a to 10f, which are rows of seeds here. The alignment of the tracks 10a to 10f, as well as their number, is also not limited to the number shown here. In addition, it is conceivable that markers are also positioned on the side of the field 2 opposite the longitudinal side to terminate the tracks 10a to 10f (which is not shown in the present FIG. 2).

The method on which the system 1 is based has already been described above with reference to FIG. Starting from the illustration in FIG. 2, the stationary markers 6a to 6f are each set at one end of a track 10a to 10f. The base station 4 is set up at the edge of the field. This can be set up at a different location every day. A lengthy calibration does not have to be carried out, a short calibration via GNSS is sufficient. As a result of this procedure, the base station 4 has a different, not very precise global position every day. This global position of the base station 4 found in this way is occupied with an unknown but constant error as long as the base station is in one place. If the mobile base station 4 is set up at a different location, the global position and the error change, but this remains constant again for the set up period.

In the present exemplary embodiment, the markers 6a to 6f are designed as pegs and have a QR code that can be identified by a respective camera attached to the vehicles 8a to 8f. The marker 6a to 6f is stationary, that is to say remains permanently in one position. In contrast to the position of the base station 4, this position never changes.

When the vehicle 8a to 8f, here for example an autonomous field robot, drives over the marker 6a to 6f, or reaches a distance to be achieved in another predetermined manner, the QR code of the marker 6a to 6f is recorded with the camera the position relative to the vehicle 8a to 8f is known. The vehicle 8a to 8f also knows its position relative to the base station 4. Thus, the base station 4 can be assigned global coordinates that do not have to be globally exact.

However, this procedure ensures that all coordinates that the vehicle 8a to 8f determines on the field 2, viewed relative to the position of the respective marker 6a to 6f, are always exact and repeatable.

According to a further exemplary embodiment, not shown, the method can also be used in a system without a local base station 4. In this case, a network of existing global stations is used instead of the mobile base station 4. In this case, a correction vector would be faulty. The error in the correction vector would have a relatively small drift, that is to say only slightly over a short period of time to change. The vehicle 8a to 8f would detect a marker 6a to 6f at the beginning of a path 10a to 10f and thus calculate the current error in the correction vector and use it for compensation. The correction value determined in this way would get worse with increasing time. In order to counteract this, the vehicle 8a to 8f, as in the exemplary embodiment described above, must detect further markers 6a to 6f at regular (time) intervals. So the correction is calculated repeatedly.

Based on the exemplary embodiment according to FIG. 2, FIG. 3 shows a detailed illustration of a system according to the invention with two base stations 4, a marker 6a and a vehicle 8a. Vectors d1, d2 are drawn between the devices of the system.

The illustration in FIG. 3 shows a snapshot; the following statements relate to a static moment of the system. This description makes it clear how the global coordinates of the two base stations 4 are calculated.

The vector d1, d2 between the marker 6a and the vehicle 8a is constant, regardless of where the base station 4 is set up in the area of the system 1 and the error with which the position is afflicted with regard to an exact positioning via GNSS. The total vector consists of the sum of the two vectors dla, d2a from the marker to the base station 4 and the vector dlb, d2b from the base station 4 to the vehicle 8a. This dependency of the distances changes with each movement along the path 10 of the vehicle 8a, but applies repeatedly for each snapshot.

A method and a system for assigning coordinates to a base station are disclosed.

Claims

Expectations

1. A method for assigning coordinates to at least one mobile base station (4), wherein at least one stationary marker (6) is used, with the steps

Setting up the base station (4);

Determining a relative position between a vehicle (8) and the base station (4); and

Calculating the coordinates of the base station (4) based on the relative position between the vehicle (8) and the base station (4).

2. The method according to claim 1 with the additional steps

Detecting the marker (6) with the vehicle (8)

Determining a relative position between the vehicle (8) and the marker (6), the calculation of the coordinates of the base station (4) also being based on the relative position between the vehicle (8) and the marker (6).

3. The method according to any one of the preceding claims, characterized in that the at least one marker (6) has an individual marking for unambiguous identification.

4. The method according to any one of the preceding claims, characterized in that the calculated coordinates are assigned to the base station.

5. The method according to claim 4, characterized in that the at least one vehicle (8) can be positioned by the base station (4) after the assignment of the coordinates.

6. The method according to any one of the preceding claims, characterized in that the relative position between the vehicle (8) and the marker (6) is determined by detecting the marker (6) by a device attached to the vehicle (8).

7. The method according to claim 6, characterized in that the device is a camera.

8. The method according to any one of the preceding claims, characterized in that a vector between the vehicle (8) and the marker (6) is known.

9. The method according to any one of the preceding claims, characterized in that a vector between the base station (4) and the marker (6) is known.

10. The method according to any one of the preceding claims, characterized in that an autonomous field robot is used as the vehicle (8).

11. System for applying a method according to one of the preceding claims, with at least one mobile base station (4) and with at least one vehicle (8), each having at least one transmitter and one receiver and wirelessly connectable to one another, and with at least one marker (6), characterized in that the mobile base station (4) can be assigned coordinates via relative positions between the base station (4) and marker (6) and between the base station (4) and the vehicle (8).

12. System according to claim 11, characterized in that the vehicle (8) is designed to travel along specified paths (10) with a high level of repeatability.