FR3070757A1 - AIRCRAFT NAVIGATION SYSTEM AND METHOD FOR SAVING MAGNETIC FIELD COMPENSATION DATA IN SUCH A SYSTEM - Google Patents

Abstract

An aircraft navigation system (1) comprising: - a magnetic field measuring device (2) having a magnetic field sensor (23) and a memory (22); a controller (3) adapted to obtain definition data of a magnetic field compensation model; - a communication link (6) connecting the magnetic field measuring device and the controller, on which the magnetic field measuring device transmits magnetic field values measured by said sensor; said navigation system being characterized in that: said controller is adapted to transmit on said link a model save command and said obtained definition data; said magnetic field measuring device being adapted to receive the backup command and the transmitted definition data and to, according to said command, store in the memory, said definition data.

Description

Aircraft navigation system and method for saving magnetic field compensation data in such a system

The present invention relates to aircraft navigation systems comprising a magnetic field measurement device, typically a magnetometer, suitable for measuring the terrestrial magnetic field and for transmitting the measurements over a communication link to a unit processing these measurements. . For example, the unit deduces a defect compensation model from the magnetic field measurements, and / or deduces a magnetic heading from the aircraft as a function of these transmitted field measurements and of the compensation model.

These defects in the magnetic field measurements include for example: disturbances of soft iron, corresponding to the influence, near the magnetometer, of ferromagnetic elements which are not completely magnetized which magnetize under the influence of the external field;

so-called hard iron disturbances, due to the presence of magnetized ferromagnetic materials on the aircraft; and imprecise alignment between the aircraft repository and that of the magnetometer when installing the magnetometer.

More specifically, the present invention relates to an aircraft navigation system comprising:

- a magnetic field measurement device comprising a magnetic field sensor and a memory;

- a controller adapted to obtain data defining a magnetic field compensation model associated with said magnetic field measurement device;

- A communication link connecting the magnetic field measurement device and the controller, the magnetic field measurement device being adapted to transmit, on said link, magnetic field values measured by said sensor.

Such a system appears in particular in an artificial horizon architecture, also called "stand-by instrument".

It is necessary, in such backup architectures, to set up a backup of the compensation model which can be used in the event of loss of the model stored in the unit which uses it operationally. Different solutions exist today. For example, an external maintenance means is connected to save and then restore, if necessary, the coefficients of the compensation model. Or a memory module is mounted on the aircraft to store this backup. Or the backup is made via a maintenance computer integrated into the aircraft.

However, these solutions have drawbacks, in particular in view of the occurrence of aircraft maintenance operations: the use of an external maintenance means introduces cumbersome implementation and requires switching off and disconnection of the wiring of the system; the integration of a memory module results in an increase in the cost, mass and electrical consumption of the aircraft while the use of a maintenance computer requires the adaptation of software interfaces at the system level .

To this end, according to a first aspect, the invention provides an aircraft navigation system of the aforementioned type characterized in that said controller is adapted to transmit, on said link, a command to save the model and said definition data obtained. ;

said magnetic field measuring device being adapted to receive, on said link, the backup command and the transmitted definition data and for, as a function of said received backup command, memorize in the memory, said definition data.

The invention thus makes it possible to save the compensation model in the most reliable unit of the system, without requiring external means or communication links other than those existing. The magnetometer is indeed intrinsically more reliable than the more complex calculation units (and in addition, following a disassembly of the magnetometer, a new definition of the compensation model is anyway necessary).

In embodiments, the aircraft navigation system according to the invention further comprises one or more of the following characteristics:

- The controller is adapted to transmit, on said link, a model restitution command and the magnetic field measurement device is adapted to receive, on said link, the restitution command and for, as a function of said received restitution command , extracting from the memory, the model definition data and for transmitting them over said link; the controller being adapted to receive said transmitted definition data;

the model definition data define coefficients of a hard iron vector and a soft iron matrix associated with the magnetic field measurement device and represent compensation for measurement faults in the terrestrial magnetic field due to a defect d alignment between the magnetic field sensor and the aircraft and with other magnetic fields measured by the magnetic field sensor, said coefficients having been calculated as a function of magnetic field values measured by said device;

the controller is adapted to automatically detect the provision of updated model definition data corresponding to the magnetic field measurement device and following said detection, to transmit, on said link, a command to save the model and said data updated definition;

- the communication link is a serial bus;

- the controller includes an artificial horizon backup instrument powered by the emergency power network.

According to a second aspect, the present invention provides a method for saving compensation data for magnetic field measurements in an aircraft navigation system comprising:

a device for measuring the magnetic field comprising a magnetic field sensor and a memory, a controller, a communication link connecting the device for measuring the magnetic field and the controller, the method comprising the following steps:

- obtaining by the controller of the definition data of a magnetic field compensation model associated with said magnetic field measurement device;

- Transmission by the magnetic field measurement device, on said link, of the magnetic field values measured by said sensor;

said process being characterized in that it comprises the following stages:

- transmission by said controller, on said link, of a command to save the model and said definition data obtained;

reception, on said link, by said device for measuring the magnetic field of the backup command and of the definition data transmitted and storage, as a function of said saved command, of said definition data, in the memory.

These characteristics and advantages of the invention will appear on reading the description which follows, given solely by way of example, and made with reference to the accompanying drawings, in which:

FIG. 1 represents a view of a navigation system of an aircraft in an embodiment of the invention;

FIG. 2 is a flow diagram of steps implemented for saving a compensation model in an embodiment of the invention;

FIG. 3 is a flow chart of steps implemented for the restitution of a compensation model saved in an embodiment of the invention.

FIG. 1 represents a navigation system 1 of an aircraft in an embodiment of the invention. The aircraft, not shown, is for example, an airplane, a helicopter, a drone, etc. The navigation system 1 adapted to be, in operational mode, on board the aircraft, is for example an emergency instrument of the artificial horizon type supplied by the aircraft's uninterrupted power supply network and which serves to guide the pilot in theft especially in the event of loss of primary instruments or of the primary supply network.

In the embodiment considered, the navigation system 1 comprises a measurement device 2, a master controller 3 and a fallback controller 4 ensuring the calculation of the aircraft's magnetic compensation model, if necessary another processing unit 5 and a communication means 6 connecting together the measuring device 2, the master controller 3, the fallback controller 4 and the processing unit 5.

The communication means 6 comprises, in the embodiment considered, a serial bus, for example RS422 or ARINC (Aeronautical Radio, incorporated) ^(R) .

The data is transmitted on the bus 6 for example in the form of frames comprising a header indicating the recipient and the transmitter and a frame body comprising the useful data.

The measurement device 2 is for example a digital magnetometer 2. It comprises for example a microcontroller 21, a memory 22 and a terrestrial magnetic field sensor 23. The microcontroller 21 ensures the cyclic emission of the measurements of the magnetic field from the sensor 23, and transmits these measured field values, and the associated measurement times, to the controller 3, the fallback controller 4 and the processing unit 5 via the bus 6.

The microcontroller 21 is suitable for example for transmitting / receiving the data of aircraft magnetic compensation models saved / to be saved in its memory 22, this as a function of corresponding commands received via the bus 6 coming from the master controller 3 , the fallback controller 4 or, if applicable, the processing unit 5.

In memory 22, factory calibration information of the magnetometer 2 has been previously stored in the factory and is used by the magnetometer 2.

The master controller 3 comprises a computer 31, a memory 32 and a man-machine interface block (HMI) 33 comprising for example a screen and control keys. It is suitable for autonomously calculating the magnetic compensation model of the carrier and orchestrating the operation of the measurement device 2, the fallback controller 4 and the processing unit 5 (and possibly other units) via the bus. 6. In the embodiment considered, the master controller 3 is adapted to further determine and deliver information, relating to the aircraft, of attitude relative to the horizon, of altitude and of speed.

In the embodiment considered, the master controller 3 is adapted to perform, in a compensation definition phase, the calculations for determining the compensation model of the magnetometer 2, comprising the determination of the coefficients of the soft iron matrix (generally a 3x3 matrix reflecting soft iron disturbances and alignment problems) and of the hard iron vector (generally of dimension 3 translating hard iron disturbances) corresponding to magnetometer 2 as installed in the aircraft, as a function of measured field values transmitted by the magnetometer 2 (in other embodiments, the model is determined by another entity which transmits it to the master controller 3). Different methods exist for determining these coefficients. Such a compensation definition phase is controlled by the master controller 3 after the installation of the magnetometer 2 and if necessary at other occurrences, to update the model.

The fallback controller 4 is a replica of the master controller 3 and is adapted to take the functional place of the master controller 3 in the event of failure of the latter or of functional switching selected at the system level of the aircraft. Thus, the fallback controller 4 comprises a computer 41, a memory 42, an HMI 43.

In the embodiment considered, the additional processing unit 5 is adapted to receive the magnetic field values transmitted on the bus 6, to calculate, compensated magnetic field values according to the received values and the current compensation model and to deduce a magnetic heading from the aircraft.

In the embodiment considered, the processing unit 5 is further adapted to perform, in a compensation definition phase, the calculations for determining a specific compensation model of the magnetometer 2, for example in the form of '' a compensation reinforcement initialized from the compensation model calculated by the master controller 3 or the fallback controller 4.

The processing unit 5, including in particular a microcontroller and a memory storing among other things software instructions, is adapted to transmit on the bus 6 intended for the master controller 3, the coefficients of the determined compensation model, called hereinafter updated coefficients, and to use them, after validation received from the master controller 3, to calculate the compensated fields.

Steps of a backup method 100, in one embodiment of the invention, of the compensation model thus transmitted to the master controller 3 are now described with reference to FIG. 2.

In a step 101, the master controller 3 receives the coefficients of the updated compensation model. In a step 102, the master controller 3 transmits on the bus 6 a write command to the magnetometer 2 also comprising the updated coefficients received. In a step 103, the magnetometer 2 receives the write command. Following the reception of this write command from the master controller 3, the microcontroller 21 stores the updated coefficients received in the memory 22 of the magnetometer 2, in place of the coefficients previously memorized if necessary for example.

The microcontroller 21 is adapted, for example, to carry out such a backup only if the write command comes from the master controller 3 (or the fallback controller 4 if the latter takes the place of the master controller 3). In one embodiment, any write conflict by two master controllers 3 or 4 is prevented by hardware configuration of the RS422 transmit / receive interfaces (the CEnable signal of the controllers TX drivers is managed at the system level by secure software configuration during their self-test, then modified as necessary during operation in the event of system reconfiguration).

According to the embodiments, a write command is sent by the master controller 3 for example following the reception of an operator command via ΙΊΗΜ 33, or automatically, at predefined time intervals, or automatically as soon as a new compensation model is detected available.

Steps of a method 200 for restoring a compensation model thus saved in the memory of the magnetometer are now described with reference to FIG. 2, in an embodiment of the invention.

In a step 201, the master controller 3 transmits on the bus 6 a read command to the magnetometer 2 requiring the reading and the supply of the saved compensation model. In a step 202, the magnetometer 2 receives the read command. Following receipt of this read command, the microcontroller 21 extracts the updated coefficients recently saved in the memory 22 of the magnetometer 2 and sends these coefficients on the bus 6 to the master controller

3.

In a step 203, the master controller 3 receives these coefficients. In one embodiment, these coefficients were transmitted with a signature of all of the coefficients and in such a case, the master controller 3 is adapted to compare the signature received and a signature that the master controller 3 calculates from the coefficients received to verify the integrity of the data received based on the comparison.

The microcontroller 21 is adapted, for example, to carry out such an extraction only if the read command comes from the master controller 3 (or the fallback controller 4 if the latter takes the place of the master controller 3). The serial bus interface drivers on the master controller 3, the fallback controller 4 and the processing unit 5 are adapted in secure configuration upon initialization, then in operation, to avoid any write conflict on the bus serial, for example by guaranteeing a single master controller for writing to magnetometer 2 at the electrical signal level. Conversely, the transmission controlled by a controller to the magnetometer 2 of the data of the compensation model feeds the various controllers in reception on the bus 6.

According to the embodiments, a read command is sent by the master controller 3 for example following the reception of a command from an operator via ΓΙΗΜ 33, or else automatically, at predefined time intervals, or again following a notification received by the master controller 3, for example from the processing unit 5, after a maintenance operation of this unit, or each time the master controller and the processing unit are powered up.

In one embodiment, on the screen of ΓΙΗΜ 33 the following fields are displayed:

- attitude, altitude, speed of the aircraft;

- last calculated compensated heading value;

a field giving rise, if selected by an operator, to a command to read the compensation model to the magnetometer 2 and, once the reading has been carried out, to a command to display on the screen, the coefficients of the model read;

a field giving rise, if selected by an operator (otherwise the backup operation is automatically ensured when the compensation model is valid and the aircraft on the ground) to a command to save the compensation model to the magnetometer 2, and once the backup has been duly performed, the display of the successful completion of the backup.

The present invention thus makes it possible to propose a simple, secure solution, of least impact as regards the component cost and operating cost in terms of duration, weight, additional constraint (le). The existing memory of the magnetometer is advantageously used to store the compensation model. It does not require any dedicated or additional physical communication link, no additional hardware resource such as a connector or a so-called “discrete” signal to reserve and wire at the main connector of magnetometer 2. There is an increase in overall reliability linked to the addition of the backup function in the navigation system according to the invention without the addition of additional hardware. The reliability of the field measurement device being approximately 10 times higher than that of the computers where the backup of the compensation model could be stored beforehand, the present invention induces a significant reduction in the cost induced by new compensations since in case of dismantling of a computer in a system according to the invention, no additional compensation operation has to be carried out.

In addition, the backup takes place while keeping the various modules powered up, facilitating maintenance operations and significantly reducing the operating cost over time compared to other existing solutions.

Claims (10)

1. - Aircraft navigation system (1) comprising: - a magnetic field measurement device (2) comprising a magnetic field sensor (23) and a memory (22); - a controller (3) adapted to obtain data defining a magnetic field compensation model associated with said magnetic field measurement device; - a communication link (6) connecting the magnetic field measurement device and the controller, the magnetic field measurement device being adapted to transmit, on said link, magnetic field values measured by said sensor; said navigation system being characterized in that: said controller is adapted to transmit, on said link, a command for saving the model and said definition data obtained; said magnetic field measuring device being adapted to receive, on said link, the backup command and the transmitted definition data and for, as a function of said received backup command, memorize in the memory, said definition data. 2. - aircraft navigation system (1) according to claim 1, in which: - the controller (3) is adapted to transmit, on said link, a command to restore a model and the magnetic field measurement device (2) is adapted to receive, on said link, the command to restore and for, depending on from said retrieval command received, extracting from the memory the model definition data and for transmitting them over said link; - the controller being adapted to receive said transmitted definition data. 3. - aircraft navigation system (1) according to claim 1 or 2, in which the model definition data define coefficients of a hard iron vector and a soft iron matrix associated with the measurement device. of the magnetic field (2) and represent compensation for measurement faults in the earth's magnetic field due to a misalignment between the magnetic field sensor and the aircraft and to other magnetic fields measured by the magnetic field sensor, said coefficients having been calculated as a function of magnetic field values measured by said device. 4, - aircraft navigation system (1) according to one of the preceding claims, in which the controller (3) is adapted to automatically detect the provision of updated model definition data corresponding to the field measurement device. magnetic (2) and following said detection, for transmitting, on said link, a command to save the model and said updated definition data. 5. - aircraft navigation system (1) according to one of the preceding claims, in which the communication link (6) is a serial bus. 6. -Aircraft navigation system (1) according to one of the preceding claims, in which the controller (3) comprises an instrument on board an artificial emergency horizon (3) supplied by the emergency supply network. . 7, - Method for saving magnetic field compensation data in an aircraft navigation system (1) comprising: - a magnetic field measuring device (2) comprising a magnetic field sensor (23) and a memory (22), a controller (3), a communication link (6) connecting the magnetic field measuring device and the controller, the method comprising the following steps: - obtaining by the controller (3) data defining a magnetic field compensation model associated with said magnetic field measurement device; - Transmission by the magnetic field measurement device, on said link, of the magnetic field values measured by said sensor; said process being characterized in that it comprises the following stages: - transmission by said controller, on said link, of a command to save the model and said definition data obtained; reception, on said link, by said device for measuring the magnetic field of the backup command and of the definition data transmitted and storage, as a function of said saved command, of said definition data, in the memory. 8. - backup method according to claim 7, comprising the following steps: - transmission by the controller (3) over said link of a model restore command; - by the magnetic field measurement device (2), reception on said link, of the restitution command, extraction of the memory, as a function of said restitution command received, of the model definition data and transmission of said data on said liaison; - reception by the controller of said transmitted definition data. 9. - backup method according to claim 7 or 8, according to which the model definition data define coefficients of a hard iron vector and a soft iron matrix associated with the magnetic field measurement device (2) and represent compensation for measurement faults in the earth's magnetic field due to a misalignment between the magnetic field sensor and the aircraft and to other magnetic fields measured by the magnetic field sensor, said coefficients having been calculated in function of magnetic field values measured by said device. 10. - Backup method according to one of claims 7 to 9, comprising the following steps: - automatic detection by the controller (3) of the provision of updated model definition data corresponding to the magnetic field measurement device (2); and - following said detection, transmission, on said link, of a model save command and said updated definition data.