DE102021119645A1 - Correction procedures for navigation systems on scheduled flights - Google Patents

Abstract

The invention relates to a correction method for navigation systems for scheduled flights, with the steps: a) performing a scheduled flight b) determining the position of the aircraft using a terrestrial NavAid element c) determining the position of the aircraft using a GNSS navigation system d) correcting the position of the terrestrial NavAid -Elements using the GNSS navigation system.

Description

The invention relates to a correction method for navigation systems on scheduled flights.

It is known from the prior art to use so-called NavAid elements to support navigation in aircraft. These can be terrestrial systems, for example, which the aircraft can use to determine its position. Typically, such systems are less accurate than GNSS navigation systems. Most measurements based on NavAid elements are therefore subject to a measurement error.

In order to quantify this, it is known from the prior art to carry out inspection flights using specially equipped aircraft. These aircraft have special measuring equipment that has a particularly high level of accuracy. Inspection flights are carried out for such a NavAid element at regular intervals (usually approx. 6 months), so that the measurement error existing for this NavAid element can be quantified and thus corrected.

Such inspection flights generate a great deal of effort and can therefore only be carried out at relatively large time intervals.

• - WO 2011009109 A2
• - US 8736482 B2
• - US 7546183 B1
• - US 4792904 A

Methods for correcting navigation data in air traffic are known from:

• - WO 2011009109 A2
• - US8736482B2
• - US7546183B1
• - US4792904A

The object of the invention is to provide a simplified correction method for aircraft navigation systems.

The object is achieved according to the invention by the features of claim 1.

1. a) Es wird ein Linienflug durchgeführt. Bei einem Linienflug kann es sich um jeglichen Flug handeln, der zu einem bestimmten Zweck durchgeführt wird, der nicht das Korrigieren eines Navigationssystems bzw. eines NavAid-Elements betrifft. Hierbei kann es sich beispielsweise um einen Passagierflug oder um einen Frachttransportflug handeln, sei es mit einem Starrflügler oder einem Hubschrauber.
2. b) Die Position des Flugzeugs wird unter Verwendung eines terrestrischen NavAid-Elements bestimmt. Hierbei kann beispielsweise bordseitig ein entsprechender Empfänger für die Signale des terrestrischen NavAid-Elements verwendet werden, um die NavAid-Elemente abzufragen.
3. c) Die Position des Flugzeugs wird unter Verwendung eines GNSS Navigationssystems bestimmt. Hierbei kann es sich um ein übliches GNSS Navigationssystem handeln, das in jedem Linienflugzeug vorhanden ist. Es ist somit kein spezielles GNSS Navigationssystem mit einer besonders hohen Genauigkeit notwendig.
4. d) Die Position des terrestrischen NavAid-Elements wird unter Verwendung des GNSS Navigationssystems korrigiert.

The correction method according to the invention for navigation systems on scheduled flights comprises the following steps:

1. a) A scheduled flight is operated. A scheduled flight can be any flight operated for a specific purpose other than correcting a navigation system or NavAid element. This can be, for example, a passenger flight or a cargo transport flight, be it with a fixed-wing aircraft or a helicopter.
2. b) The position of the aircraft is determined using a NavAid terrestrial element. In this case, for example, a corresponding receiver for the signals of the terrestrial NavAid element can be used on board in order to interrogate the NavAid elements.
3. c) The position of the aircraft is determined using a GNSS navigation system. This can be a standard GNSS navigation system that is present in every commercial aircraft. A special GNSS navigation system with a particularly high level of accuracy is therefore not necessary.
4. d) The position of the terrestrial NavAid element is corrected using the GNSS navigation system.

The method according to the invention makes it possible in a particularly simple manner to correct the NavAid elements used in aircraft navigation systems. These usually have lower accuracy and more errors than GNSS navigation systems. However, according to the invention, it is not necessary to carry out inspection flights with special equipment for this. Rather, it is possible to use a large number of scheduled flights, which are carried out anyway, to collect correction data using the GNSS navigation systems present in the scheduled aircraft and thereby correct the NavAid elements.

Correction data for each NavAid element is preferably aggregated using a large number of GNSS navigation data which are collected on a large number of scheduled flights. An error model is then created for each NavAid element. A large number of GNSS correction data are thus collected due to the large number of scheduled flights, without a greater effort having to be made for this. GNSS correction data are thus used, which do not have to be particularly accurate, since they were collected using normal GNSS navigation equipment, which is already present on scheduled flights. This data is less accurate than data collected during inspection flights using special equipment. This lower level of accuracy is offset by the far greater frequency at which this data can be collected. This is because they are not only collected during inspection flights, but basically on every scheduled flight.

For example, fixing a NavAid item using more than 2 Correction data records are made with a permissible standard deviation of at least 1 m.

In a preferred embodiment, only such GNSS correction data are stored and/or transmitted by the aircraft for creating the error model that belong to a NavAid element for which there is only a number of correction data that is below a defined threshold value. In this way it can be avoided that GNSS correction data for NavAid elements for which a very large number of correction data is already available is unnecessarily transmitted again. This can be the case, for example, on heavily frequented flight routes on which a sufficiently large number of GNSS correction data has already been collected in the past through the scheduled flights carried out.

It is also preferred that, given at least two possible flight routes to a desired destination, a route is suggested along those NavAid elements for which more useful GNSS correction data can be expected. In other words, the flight route is thus also determined according to the criterion on which flight route more useful GNSS correction data can be collected. More useful GNSS correction data can be assumed for those NavAid elements for which the confidence interval is still relatively large, i.e. for which no or comparatively few corrections have been made. The confidence interval is the parameter to be optimized. If there are several routes or an infinite number of routes to choose from during a flight, then it is advantageous to select the route that runs along those NavAid elements for which the fewest correction data are available. Along these routes there are NavAid elements with the largest confidence intervals, which then improve by 1/(2*N^(3/2)) with each flight, i.e. the derivative of 1/N^(1/2)) .

Preferred embodiments of the invention are explained below with reference to figures:

The figure shows the correction according to the invention of a NavAid element using GNSS navigation data. A reference position of the aircraft is determined using this GNSS navigation data. Based on this reference position, a reference distance or reference angle Γ to the NavAid element can be determined. A measured value r is also determined on the basis of the measurement data of the NavAid element, which also designates the distance or angle of the aircraft to the NavAid element. A measurement error can thus be calculated as follows: $$e_{\mathrm{right}}=\widehat{\mathrm{right}}-\mathrm{right}.$$

Each new value of Er is stored in a memory with historical values of Er collected on past flights. There is thus a memory for a large number of aircraft positions. If a memory for a specific aircraft position contains a sufficient number of correction measurements, it can be assumed that the position determined by the NavAid element at this aircraft position is sufficiently reliable so that the NavAid element can be used at this aircraft position.

The method according to the invention offers advantages in particular when the transmission channel for a terrestrial NavAid element changes over time due to external circumstances. The method according to the invention enables faster correction of the navigation data that has been corrupted as a result.

As a concrete example of the use of the method according to the invention, a scenario can be considered in which ten correction measurements with a standard deviation of one meter would be necessary for verification of the measured position by a NavAid element at a specific aircraft position. Assuming that a 95% confidence interval can be achieved in this way, the same confidence interval could be achieved with 100 measurements with a standard deviation of ten meters. Within the scope of the method according to the invention, these could be carried out by GNSS measurements on normal scheduled flights without the use of special equipment.

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

• WO 2011009109 A2 [0005]
• US 8736482 B2 [0005]
• US7546183B1 [0005]
• US4792904A [0005]

Claims (5)

Correction procedure for navigation systems on scheduled flights, comprising the steps: a) Operation of a scheduled flight b) determining the position of the aircraft using a NavAid terrestrial element c) determining the position of the aircraft using a GNSS navigation system d) correcting the position of the terrestrial NavAid element using the GNSS navigation system. Correction procedures for navigation systems on scheduled flights claim 1 , characterized by - aggregating correction data for each NavAid element using a plurality of GNSS navigation data collected on a plurality of scheduled flights - creating an error model for each NavAid element. Correction procedures for navigation systems on scheduled flights claim 1 or 2 , characterized in that a NavAid element is corrected using more than 1 correction data sets with a permissible standard deviation of 1 m. Correction procedures for navigation systems on scheduled flights claim 1 - 3 , characterized in that only such GNSS correction data are transmitted from the aircraft for the creation of the error model, which belong to a NavAid element for which there is only a number of correction data that is below a defined threshold value. Correction procedures for navigation systems on scheduled flights claim 1 - 4 , characterized in that with at least two possible flight routes to a desired destination, a route is suggested along NavAid elements for which more useful GNSS correction data can be expected.

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