DE102018200264A1 - Automatic calibration of a reference station for DGNSS - Google Patents

Abstract

A method (100) of operating a reference satellite navigation system (5), DGNSS (3), wherein both code-based information (33a-33d) is extracted (110) from the satellite signals (32a-32d) of the GNSS (3) the phase position (34) of the satellite signals (32a-32d) are determined (120), and from the code-based information (33a-33d) and from the phase position (34) in conjunction with the own position (5a) of the reference station (5) correction data (50) for determining the position of mobile units (1) with the GNSS (3) are evaluated (130), wherein the position (5a) of the reference station (5) is determined by the following steps:
The code-based information (33a-33d) and the phase position (34) are transmitted (140) to an external correction service (6);
In the external correction service (6) the code-based information (33a-33d) and the phasing (34) are merged (150) with additional information (61) containing at least satellite orbit information (62) and clock information (63);
As a result of this merge (150), the exact position (5a) of the reference station (5) is determined (160).
Associated computer program.

Description

The present invention relates to a method for automatically calibrating the position of a reference station for a DGNSS so that the reference station can provide correction data for highly accurate mobile unit positioning.

State of the art

Due to confined space, it is not always possible on construction sites to allocate a fixed storage space to each item. For frequently used items, and especially for consumables, continuous bookkeeping, in terms of use and storage location, is impractical. As a result, a lot of work is spent on construction sites looking for items and materials.

The US 2014 240 143 A1 discloses to determine the position of the object by means of global satellite navigation systems, GNSS, and to transmit the position information by means of sub 1 GHz radio signals. The achievable lateral accuracy is between 15 and 35 meters.

From the EP 0 826 980 A2 and from the DE 195 39 302 B4 It is known to use a reference station whose position is well known to determine correction data for the satellite signals. With the help of this correction data, the position of mobile units, which in turn have a GNSS receiver, can be improved to less than 1 m. A navigation system based on GNSS using such a reference station is referred to as a differential GNSS, or DGNSS for short.

Disclosure of the invention

In the context of the invention, a method for operating a reference station for a differential satellite-based navigation system, DGNSS, has been developed. In this method, with a correspondingly equipped GNSS receiver of the reference station both code-based information extracted from the satellite signals of the GNSS and determines the phase of the satellite signals. Correction data for determining the position of mobile units with the GNSS are evaluated in conjunction with the own position of the reference station from the code-based information as well as from the phase position.

In this case, this evaluation is not necessarily limited to the reference station itself, but can for example be made on an external server. The exact position of the reference station does not necessarily have to be known on the reference station itself. Rather, for example, the reference station can transmit a data stream to the external server, which contains the code-based information and the phase position, and / or a precursor thereof, for which the exact position of the reference station is not yet needed. The correction data can then be determined on the external server.

The positioning of mobile units is improved by merging this correction data with information that the mobile units have received from the GNSS. This merging can be done in any way. For example, the correction data can be transmitted via a radio interface to the mobile units. However, the reference station can also, for example, receive the information that the mobile units have received from the GNSS via a radio interface and merge it with the correction data itself. However, the information from the mobile units and the correction data can also, for example, be fed independently of an external server and further processed there to the exact positions of the mobile units.

The position of the reference station is determined by transmitting the code-based information and the phase position to an external correction service. In the external correction service, the code-based information and the phase are merged with additional information containing at least satellite orbit information and clock information. As a result of this merge, the exact position of the reference station is determined.

The exact position of the reference station can now be transmitted, for example, from the external correction service to the reference station. Then the reference station can calculate finished correction data. However, the exact position of the reference station can also be transmitted, for example, to an external server, which calculates the correction data and merges it with the GNSS information received from the mobile units.

It was recognized that in this way the handling of the reference station, in particular for the localization of objects on construction sites can be significantly facilitated. Just as it is not always possible on construction sites to allocate a fixed storage space to equipment and materials, even a reference station can not always be allocated an immovable space for the entire duration of the construction work. For example, a reference station may be mounted on a construction vehicle, and / or on a temporary construction site facility. It may then be necessary in the course of the work to relocate this vehicle or temporary facility.

Any such change of location makes it necessary to re-determine the exact position of the reference station. A manual calibration is associated with a high expenditure of time and money. Furthermore, this requires a high-precision surveying system that can only be operated by qualified specialist personnel.

By using the external correction service, however, it becomes possible to automatically determine the position of the reference station without a fixed point with a precisely known position within a few minutes. As a result, it is not even necessary to leave the reference station at the construction site for the entire duration of the construction work. Because of the frequent thefts on construction sites, it is common practice at the end of a working day to take all easily transportable valuables. A reference station is a high-quality precision instrument, which therefore fits into the predator's scheme of thieves. So far, the effort to re-measure the reference station every morning was too big. Now that this effort is significantly reduced, it becomes practicable to dismantle the reference station at the end of a working day and rebuild it the next morning.

The code-based information and the phase position could in principle also be combined in the reference station itself with the additional information. For this purpose, the reference station could, for example, obtain the data stream of the additional information from the external correction service. However, it is advantageous in two respects to merge the information from the reference station in the external correction service with the additional information. On the one hand, a higher computing power is available in the external correction service than in the reference station, which can be a portable device. On the other hand, the data stream of the additional information has a significantly larger volume than the data stream of the information from the reference station. On a construction site, there is often no fixed Internet connection available, but mobile telephony has to be used, increasing costs with the volume of data.

In a particularly advantageous embodiment, the external correction service is designed to determine the exact position of the reference station according to the Precise Point Positioning method (PPP). This method is in contrast to conventional, differential evaluation approaches without immediate availability of observations of a reference station, or a network of reference stations, from. In this method, both the orbital parameters of the satellites and the clock errors are corrected. Furthermore, algorithms that correct the geometric distance between the satellite and the antenna of the receiver and models for correcting the phase observation are available. The PPP also includes a correction of the data of the observation stations due to the deformation of the earth, a compensation of tidal influences as well as a compensation of gravitational influences of sun and moon.

Advantageously, a reference station with a two-frequency receiver for the GNSS is selected. In this way, information on the influence of the ionosphere on the propagation of the satellite signals can be detected directly at the reference station, which again improves the ultimately achievable accuracy.

In a particularly advantageous embodiment, the reference station is monitored with an acceleration sensor for changes in position. Especially on a construction site, it may be the case that a construction vehicle or a temporary device carrying the reference station has to be moved, for example to make room for a work or for the passage of a vehicle. It may not be noticed or thought that the change in position will require a re-calibration of the reference station. Automatic monitoring prevents systematically calculating incorrect correction data and correspondingly falsifying the determined positions of mobile units.

For example, the position of the reference station can be invalidated if measurement results of the acceleration sensor exceed a predetermined threshold. Such an event is always at least an indication that a mechanical force has acted on the reference station or structure carrying the reference station.

However, such a force effect can also consist, for example, of an abutment which does not result in a permanent change in position. For example, a worker transporting a bulky item may hit a mast carrying the reference station. So that not every such event temporarily paralyzes the reference station, measuring results of the acceleration sensor are advantageously integrated twice over time to determine the change in position. The current position of the reference station is declared invalid if the position change thus determined exceeds a predetermined threshold.

Alternatively, or in combination, the reference station with its receiver for the GNSS are monitored for position changes. The current position of the reference station is declared invalid if the position change thus determined exceeds a predetermined threshold.

Advantageously, the position of the reference station is again determined by means of the external correction service if no further change in position has been detected for a predetermined time. In this way, on the one hand it is avoided that correction data, which immediately become invalid again at the moment of its calculation, are circulated by the reference station and possibly used for then systematically falsified mobile unit position determinations. On the other hand, resources for unnecessary positioning of the reference station are saved. A portable reference station may have limited power in batteries. Furthermore, the external correction service or the data transmission there may be associated with usage-dependent costs. By re-positioning only after a certain time without renewed movement costs can be saved here.

In a further advantageous embodiment, the reference station transmits a data stream of code-based information and the phase position to the external correction service until the external correction service responds with an acknowledgment and / or with the determined exact position of the reference station. The same amount of information from the reference station is not required at all times to accurately determine the position of the reference station. Rather, with a fixed requirement for the absolute accuracy, the required amount of information depends on the current strength of the mentioned disturbing influences and on the current satellite constellation. By means of an appropriate communication between the reference station and the external correction service, on the one hand time can be saved until the reference station can be used for the positioning of mobile units. On the other hand, data volume for transmission to the external correction service is saved.

In a further particularly advantageous embodiment, the reference station receives, via a radio interface, information from the mobile units which have derived the mobile units from GNSS signals which in turn have been received. This information can in particular already enable a position determination of the mobile units. For example, the reference station can provide the mobile units with a data stream of the correction data via the radio interface, so that the mobile units can determine their position directly very precisely.

In a further embodiment, which is particularly advantageous for use on construction sites, the reference station forwards the information received from the mobile units to an external server, and / or determines the positions of the mobile units itself from this information.

On the one hand, the mobile units can be equipped with simpler, less expensive and energy-saving hardware. On a construction site it is not known in advance which objects will be searched for later. Therefore, many objects must be provided with localizable mobile units (tags, "tags"). Accordingly, the effort for each of these units multiplies. Furthermore, due to the large number of mobile units, the aim is always to supply them with lifetime batteries in order to avoid creating any infrastructure for changing or recharging batteries.

On the other hand, a considerable amount of bandwidth can be saved in communication via the radio interface. In particular, for the use of localization systems on constantly changing construction sites, it is highly desirable to use for the radio interface a frequency band allocated for the registration-free use by the general public. For example, communication can be via LoRaWAN or another low power WAN. However, the logon free usage is then mostly subject to maximum duty cycle conditions, i. the maximum transmission time proportion, knotted.

The information sent by the mobile units has a significantly lower data volume than the correction data. The less data is transmitted on a work cycle limited radio interface, the lower the likelihood that it comes in the transmission to waiting times or even disabilities in the data transfer.

If the processing of both the information received from the mobile units and the correction data takes place on an external server, there is greater computing capacity available for this than on the reference station itself. Furthermore, this processing can also make use of the correction service, for example the position of the reference station is determined.

In particular, the method can be implemented completely or partially in software, so that, for example, an existing reference station can be caused by uploading this software when determining its own position in the manner described with an external correction service together. The software is thus an independently marketable product. The invention therefore also relates to a computer program with machine-readable instructions which, when executed on a computer, and / or on a reference station, and / or on an external correction service or server, the computer, the reference station, the external correction service or causing the external server to execute, individually or in combination, a method according to the invention.

Further measures improving the invention will be described in more detail below together with the description of the preferred embodiments of the invention with reference to figures.

list of figures

• 1 Schematische Darstellung eines Szenarios, in dem das Verfahren 100 einsetzbar ist;
• 2 Ablaufdiagramm eines Ausführungsbeispiels des Verfahrens 100.

It shows:

• 1 Schematic representation of a scenario in which the procedure 100 can be used;
• 2 Flowchart of an embodiment of the method 100 ,

To 1 receives the reference station 5 with their dual-frequency receiver 51 signals 32a - 32d from the satellites 31a - 31d of the GNSS 3 , Each of the signals 32a - 32d contains each code-based information 33a - 33d , In addition, the recipient 51 the reference station 5 also able to phase position 34 the satellite signals 32a - 32d analyze. The code-based information 33a - 33d as well as the phase position 34 be together with your own position 5a the reference station 5 to correction data 50 processed. The correction data 50 are in turn used in conjunction with via the radio interface 53 received information 11 from mobile units 1 the positions 1a the mobile units 1 to investigate. These positions 1a be sent to an external server 7 transfer.

The from the mobile units 1 sent information 11 are from satellite signals 36a - 36d Derived the mobile units 1 have received. These satellite signals 36a - 36d have other reference numerals than those of the receiver 51 the reference station 5 received satellite signals 32a - 32d because the mobile units are in positions 1a are located by the position 5a the reference station 5 is different. Accordingly, the signal delays are from the satellites 31a - 31d to the mobile units 1 other than from the satellites 31a - 31d to the reference station 5 , The mobile units 1 For example, you can use objects 2 be located on a construction site.

To your own position 5a to determine, transmits the reference station 5 the code-based information 33a - 33d as well as the phase position 34 to an external correction service 6 , There, this information will be in the steps 150 and 160 of in 2 closer explained method 100 with additional information 61 merged, the at least satellite orbit information 62 and clock information 63 contain. The position obtained as result 5a the reference station 5 will be accompanied by a receipt 64 to the reference station 5 transmitted.

The reference station 5 monitored with an accelerometer 53 whether her position 5a changed. If necessary, the current position 5a invalidated and again with the help of the external correction service 6 determined.

As by the dashed arrow between the reference station 5 and the external server 7 indicated, the reference station 5 also from the mobile units 1 received information 11 together with the correction data 50 to the external server 7 pass. The merging of this information to the positions 1a The mobile units can then be on the external server 7 carried out the positions obtained 1a then back to the reference station 1a can transmit.

2 schematically shows an embodiment of the method 100 , From the satellite signals 32a - 32d be first in block 110 the code-based information 33a - 33d and in block 120 the phase position 34 extracted. This information is in block 130 with the position 5a the reference station 5 merged to correction data 50 for the positioning of mobile units 1 to determine.

This assumes that the current position 5a the reference station 5 is still valid, ie, that the reference station 5 after determining this position 5a was not moved anymore. This can be tested in different ways.

The reference station 5 can according to block 170 with the accelerometer 52 on changes of their position 5a be monitored. It can then according to block 180 the current position 5a the reference station 5 be invalidated when the measurement results of the acceleration sensor 52 exceed a predetermined threshold. The measurement results can also according to block 185 initially be integrated twice in time, and the current position 5a the reference station 5 can according to block 190 be declared invalid if this integral exceeds a predetermined threshold.

The reference station 5 but also according to block 195 with her receiver 51 for the GNSS 3 on changes of their position 5a be monitored. The current position 5a can then according to block 200 be invalidated if the change in position thus determined 5a exceeds a predetermined threshold.

According to block 210 can then be checked, whether since the last movement of the reference station 5 at least a predetermined time has elapsed. If this is the case (truth value 1 ), become the code-based information 33a - 33d as well as the phase position 34 according to block 140 to the external correction service 6 transmitted.

The external correction service 6 performs the code-based information 33a - 33d as well as the phase position 34 according to block 150 with the additional information 61 together and determined according to block 160 the new position 5a the reference station 5 , From this point on, the reference station is 5 who has lost their qualification as such due to the change in position.

As indicated by the dashed lines in 2 indicated, according to step 145 the transmission 140 the stream of code-based information 33a - 33d and phasing 34 continue to the external correction service until the external correction service 6 according to step 165 with the new position 5a , and / or with a receipt 64 , answers.

QUOTES INCLUDE IN THE DESCRIPTION

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

Cited patent literature

• US 2014240143 A1 [0003]
• EP 0826980 A2 [0004]
• DE 19539302 B4 [0004]

Claims (13)

A method (100) of operating a reference satellite navigation system (5), DGNSS (3), wherein both code-based information (33a-33d) is extracted (110) from the satellite signals (32a-32d) of the GNSS (3) the phase position (34) of the satellite signals (32a-32d) are determined (120), and from the code-based information (33a-33d) and from the phase position (34) in conjunction with the own position (5a) of the reference station (5) correction data (50) for determining the position of mobile units (1) with the GNSS (3) are evaluated (130), characterized in that the position (5a) of the reference station (5) with the following steps is determined: • the code-based information (33a -33d) and the phase position (34) are transmitted to an external correction service (6) (140); In the external correction service (6) the code-based information (33a-33d) and the phasing (34) are merged (150) with additional information (61) containing at least satellite orbit information (62) and clock information (63); As a result of this merge (150), the exact position (5a) of the reference station (5) is determined (160). Method (100) according to Claim 1 , characterized in that the external correction service (6) is adapted to determine the exact position (5a) of the reference station (5) according to the Precise Point Positioning method. Method (100) according to one of Claims 1 to 2 , characterized in that a reference station (5) with a dual-frequency receiver (51) for the GNSS (3) is selected. Method (100) according to one of Claims 1 to 3 , characterized in that the reference station (5) with an acceleration sensor (52) is monitored for changes in its position (5a) (170). Method (100) according to Claim 4 , characterized in that the current position (5a) of the reference station (5) is invalidated when measurement results of the acceleration sensor (52) exceed a predetermined threshold (180). Method (100) according to one of Claims 4 to 5 , characterized in that for determining the change of the position (5a) measurement results of the acceleration sensor (52) are integrated twice in time (185) and the current position (5a) of the reference station (5) is declared invalid if the thus determined change of Position (5a) exceeds a predetermined threshold (190). Method (100) according to one of Claims 1 to 6 , characterized in that the reference station (5) with its receiver (51) for the GNSS (3) is monitored for changes in the position (5a) (195) and the current position (5a) of the reference station (5) is invalidated if the thus determined change of the position (5a) exceeds a predetermined threshold value (200). Method (100) according to one of Claims 4 to 7 , characterized in that the position (5a) of the reference station (5) is again determined (140-160) using the external correction service (6) if no further position change has been detected for a predetermined time (210). Method (100) according to one of Claims 1 to 8th , characterized in that the reference station (5) transmits (145) a data stream of code-based information (33a-33d) and the phase position (34) to the external correction service (6) until the external correction service (6) with an acknowledgment (64 ), and / or responds to the determined exact position (5a) of the reference station (165). Method (100) according to one of Claims 1 to 9 , characterized in that a reference station (5) is selected which is mounted on a construction vehicle, and / or on a temporary construction site device. Method (100) according to one of Claims 1 to 10 , characterized in that the reference station (5) via a radio interface (53) information (11) of the mobile units (1), which have derived the mobile units (1) in turn received GNSS signals (36a-36d) receives. Method (100) according to Claim 11 , characterized in that the reference station (5) forwards the information (11) received from the mobile units (1) to an external server (7), and / or from this information (11) the positions (la) of the mobile units (11) 11). Computer program comprising machine-readable instructions which, when executed on a computer, and / or on a reference station (5), and / or on an external correction service (6) or server (7), the computer, the reference station (5 ), the external correction service (6) or the external server (7) cause, individually or in combination, a method according to one of Claims 1 to 12 perform.

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