Navigation method and device for a vehicle, system, vehicle, computer program and associated information storage medium
Patent Information
- Application Number
- FR2022009165
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2022-09-13
- Publication Date
- 2025-02-21
- Estimated Expiration
- 2042-09-13
Smart Images
Figure 00000022_0000 
Figure 00000023_0000
Abstract
Description
Title of the invention: Navigation method and device for a vehicle, associated system, vehicle, computer program and information medium Technical field
[0001] The present invention relates to the fields of navigation and positioning. More particularly, the present invention relates to a navigation method and device for a vehicle, an associated system, vehicle, computer program and information medium. The present invention finds a particularly advantageous, although in no way limiting, application for the implementation of navigation systems for aircraft. State of the prior art
[0002] There are currently, in the state of the art, various navigation systems for vehicles. In particular, it is known to use an inertial unit on board a vehicle as a navigation system. More generally, we hereinafter refer to “inertial navigation” as a navigation solution using data from an inertial measurement unit (i.e. specific force and angular velocity). The use of inertial data to implement a navigation solution, however, requires solving the well-known problem of drift over time of inertial navigation. Indeed, small errors in measuring the specific force and angular velocity are integrated over time by inertial navigation and thus lead to increasingly large speed and position errors.
[0003] To limit the drift of inertial navigation, one prior art approach involves combining inertial data with data from a satellite positioning module, such as a GPS (Global Positioning System) module. Generally speaking, a navigation solution combining data from several sensors is referred to as a “hybrid navigation” solution. However, existing hybrid inertial-GPS navigation solutions have the following drawback: a GPS module can be easily jammed and thus experience a loss of availability. Ultimately, hybrid inertial-GPS navigation solutions do not allow a vehicle to be located reliably and precisely while guaranteeing a high level of integrity. Integrity is defined as the ability to provide, in addition to an estimated quantity (e.g.the position, speed, heading of a vehicle), a protection radius associated with this quantity, that is to say a limit increasing the estimation error with a defined probability, in particular very close to 1.
[0004] It may also be envisaged to use computer vision techniques to compensate for the drift of inertial navigation from images acquired by a vehicle. However, existing computer vision devices - both cameras and image processing algorithms - have a low level of maturity such that the reliability of these devices is low. In particular, such devices have a high hourly integrity risk. The hourly integrity risk for a navigation system is defined as the hourly risk of obtaining erroneous information, i.e. an estimated quantity whose error is greater than the protection radius. In this sense, using a computer vision device to implement a navigation solution does not make it possible to achieve a sufficient level of integrity for critical applications, such as aeronautics.
[0005] There is therefore a need for a navigation solution that can improve the level of integrity and availability of existing navigation systems. Statement of the invention
[0006] The present invention aims to remedy all or part of the drawbacks of the prior art, in particular those set out above.
[0007] To this end, according to one aspect of the invention, a navigation method for a vehicle is proposed, said method comprising steps of: - determination by a first navigation module of first navigation data of said vehicle from data from an inertial measurement unit and a satellite positioning module; and determination by a second navigation module of second navigation data of said vehicle from: data from the inertial measurement unit and images acquired by said vehicle; and further from data from said satellite positioning module and / or an altimeter.
[0008] By "navigation data", reference is made here to: data relating to the position, and / or the movement of the vehicle - such as geographic coordinates (e.g. latitude, longitude, altitude), speed, heading, etc.; and / or to protection radii associated with position / movement data. In the context of the invention, a "position" may designate an absolute position defined in relation to the terrestrial reference frame, or a relative position defined in relation to a reference position.
[0009] In the context of the invention, by "inertial measurement unit" is meant a measuring device providing, for a plurality of measurement instants, data relating to the specific force (i.e. the sum of external forces other than gravitational divided by the mass) and the angular velocity of the vehicle. In addition, the The term "inertial unit" hereinafter means a navigation device integrating over time the specific force and angular velocity data produced by an inertial measurement unit and making it possible to determine vehicle navigation data.
[0010] The proposed method makes it possible to precisely determine the navigation data of a vehicle (e.g. the position and movement data of the vehicle as well as the associated protection radii) while guaranteeing a high level of integrity and availability of the navigation system.
[0011] According to one embodiment, the step of determining navigation data by the first navigation module and the step of determining navigation data by the second navigation module are carried out concomitantly (i.e. in parallel, or simultaneously). Thus, the parallel use of two separate navigation modules (i.e. said first and second navigation modules) makes it possible to improve the resilience of the vehicle's navigation system with respect to failures of the sensors used for navigation (e.g. satellite positioning module, image acquisition device), such as a failure of the satellite positioning module, a failure of the image acquisition device, or unavailability of another sensor, etc.
[0012] Furthermore, the use of a satellite and image positioning module makes it possible to compensate for inertial navigation drift and thus to accurately determine the vehicle's navigation data.
[0013] Compared to existing navigation solutions, the proposed navigation solution, by exploiting a plurality of navigation modules, makes it possible to improve the level of integrity and availability of the vehicle navigation system while accurately determining the vehicle navigation data.
[0014] More specifically, the proposed navigation solution presents: a higher level of availability than existing hybrid inertial-GPS navigation systems; and a higher level of integrity than existing hybrid inertial-vision navigation systems.
[0015] According to one embodiment, the proposed method comprises steps of: - if said satellite positioning module is functional, providing said first navigation data to a guidance module of said vehicle; and - otherwise, provision of said second navigation data to said guidance module of said vehicle.
[0016] This embodiment allows for precise guidance of a vehicle. It should be noted that this embodiment benefits from the technical advantages of the proposed navigation solution. Indeed, precise guidance of the vehicle is enabled because the data from navigation are determined precisely.
[0017] As mentioned previously, the proposed solution uses images for navigation to compensate for inertial navigation drift. According to this embodiment, the use of navigation data determined from images by the second navigation module for vehicle guidance is conditional on unavailability of the satellite positioning module (e.g. faulty or unusable module). Thus, this embodiment makes it possible to significantly relax the constraints on the reliability (i.e. the hourly integrity risk) of the image acquisition device and the associated image processing algorithms. Thus, the proposed navigation solution makes it possible to accurately determine the navigation data of a vehicle while guaranteeing a high level of integrity, even for an image acquisition device and associated image processing algorithms of low maturity.
[0018] Indeed, the second navigation module uses, according to this embodiment, data from the satellite positioning module or the altimeter in addition to the acquired images. This makes it possible to compensate with greater precision the inertial navigation drift of the second navigation module when the satellite positioning module or the altimeter are usable. Thus, this embodiment makes it possible to maintain a precise location chain by using the different sensors when they are available.
[0019] For example, suppose that during a first period, the second navigation module uses the data from the satellite positioning module to compensate for the inertial navigation drift. Then, during a second subsequent period, the satellite positioning module is no longer available. Then, although the satellite positioning module is no longer available, the second navigation module benefits during the second period from the recalibration of the inertial navigation during the first period.
[0020] According to one embodiment, the first and second navigation modules respectively comprise an inertial unit and a Kalman filter for determining said first and second navigation data. More particularly, the first navigation module comprises a first inertial unit and a first Kalman filter for determining said first navigation data; and the second navigation module comprises a second inertial unit and a second Kalman filter for determining said second navigation data.
[0021] This embodiment makes it possible to exploit data from independent sensors of different types to determine the vehicle's navigation data efficiently, in particular in terms of the precision of the navigation data obtained and the necessary hardware and software resources (e.g., navigation resources). processing, memory resources, etc.).
[0022] More specifically, this embodiment makes it possible to implement a multi-sensor data fusion to determine vehicle navigation data. The use of an inertial unit makes it possible to determine navigation data from the inertial data; and the use of a Kalman filter makes it possible to correct this navigation data from data from the other sensors (i.e. recalibration of the inertial navigation to compensate for drift). Thus, the combination of an inertial unit and a Kalman filter makes it possible to implement a multi-sensor data fusion to accurately determine the vehicle navigation data from independent sensors of different types.
[0023] According to one embodiment, the proposed method comprises steps of: - detecting at least one terrestrial reference point in said acquired images; - determination of an observed relative position of said at least one detected terrestrial reference point with respect to said vehicle from said acquired images; - determination of an estimated relative position of said at least one detected terrestrial reference point with respect to said vehicle from a position of said vehicle determined by the second navigation module and a known position of said at least one terrestrial reference point; and - determination of said second navigation data from the difference between the observed and estimated relative positions of said at least one terrestrial reference point in relation to said vehicle.
[0024] In the context of the invention, a “reference terrestrial point” is a terrestrial point whose position (e.g. the geographical coordinates) is known. Hereinafter, a reference terrestrial point is also referred to by the term “landmark”.
[0025] This embodiment makes it possible to compensate for the drift of the inertial navigation of the second navigation module from images acquired by the vehicle.
[0026] It should also be mentioned that, within the scope of the invention, other embodiments could be envisaged in which navigation data are determined from acquired images, for example using visual odometry techniques, cartographic registration techniques, machine learning algorithms, etc.
[0027] According to one embodiment, said step of detecting at least one reference terrestrial point in the acquired images comprises steps of: - selection of a portion of at least one acquired image, the coordinates of said portion being determined from a known position of said at least one terrestrial reference point, from a position of said vehicle determined by the second navigation module and information relating to the accuracy of said determined position of said vehicle provided by the second navigation module; and - detection of said at least one terrestrial reference point in said portion of said at least one acquired image.
[0028] This embodiment is advantageous in that it makes it possible to use only a portion of the image (i.e. a region of interest) to detect a reference terrestrial point and thus to restrict the portion of the image to be processed. More generally, this embodiment makes it possible to reduce the hardware and software resources (e.g. processing resources, memory resources, etc.) necessary for detecting a reference terrestrial point in acquired images and therefore for determining navigation data from acquired images.
[0029] According to another aspect of the invention, there is provided a navigation device for a vehicle comprising: - a first navigation module configured to determine first navigation data of said vehicle from data from an inertial measurement unit and a satellite positioning module; and - a second navigation module configured to determine second navigation data of said vehicle from data from the inertial measurement unit and images acquired by said vehicle; and further from data from said satellite positioning module and / or an altimeter.
[0030] The proposed navigation device has the advantages described above in connection with the proposed navigation method. According to one embodiment, the navigation device implements all or part of the steps of the proposed navigation method.
[0031] According to one embodiment, the proposed device comprises a control module configured to: - if said satellite positioning module is functional, providing said first navigation data to a guidance module of said vehicle; and - otherwise, provide said second navigation data to said guidance module of said vehicle
[0032] According to one aspect of the invention, there is provided a navigation system for a vehicle comprising: a navigation device according to the invention; an inertial measurement unit; a satellite positioning module; and an image acquisition device.
[0033] The proposed navigation system has the advantages described above in connection with the proposed navigation method. According to one embodiment, the navigation system The proposed navigation process implements all or part of the steps of the proposed navigation process.
[0034] According to one embodiment, the navigation system comprises a computer vision device configured to determine at least one position of the vehicle from the images acquired by said image acquisition device.
[0035] According to one embodiment, the navigation system comprises a guidance module configured to guide said vehicle based on navigation data determined by said navigation device according to the invention.
[0036] According to one aspect of the invention, there is provided a vehicle comprising a navigation system according to the invention.
[0037] According to one aspect of the invention, there is provided a computer program comprising instructions for implementing the steps of a method according to the invention, when the computer program is executed by at least one processor or computer.
[0038] The computer program may be formed of one or more sub-parts stored in the same memory or in separate memories. The program may use any programming language, and be in the form of source code, object code, or intermediate code between source code and object code, such as in a partially compiled form, or in any other desirable form.
[0039] According to one aspect of the invention, there is provided a computer-readable information medium comprising a computer program according to the invention.
[0040] The information carrier may be any entity or device capable of storing the program. For example, the carrier may comprise a storage means, such as a non-volatile memory or ROM, for example a CD-ROM or a microelectronic circuit ROM, or a magnetic recording means, for example a floppy disk or a hard disk. Furthermore, the storage medium may be a transmissible medium such as an electrical or optical signal, which may be conveyed via an electrical or optical cable, by radio or by a telecommunications network or by a computer network or by other means. The program according to the invention may in particular be downloaded onto a computer network. Alternatively, the information carrier may be an integrated circuit in which the program is incorporated, the circuit being adapted to execute or to be used in the execution of the method in question.
[0041] Brief description of the drawings
[0042] Other features and advantages of the present invention will become apparent from the description provided below of embodiments of the invention. These embodiments lisation are given as an illustrative example and are not intended to be limiting. The description provided below is illustrated by the attached drawings:
[0043] [Fig.l] [Fig.l] schematically represents an example of software and hardware architecture of a navigation system according to an embodiment of the invention;
[0044] [Fig.2A]-[Fig.2B] Figures 2A and 2B represent, schematically and in flowchart form, steps of a navigation method according to an embodiment of the invention; and
[0045] [Fig.3] [Fig.3] schematically represents an example of software and hardware architecture of a navigation system according to an embodiment of the invention.
[0046] Description of the embodiments
[0047] The present invention relates to a navigation method and device for a vehicle, as well as an associated system, vehicle, computer program and information medium.
[0048] [Fig.l] schematically represents an example of software and hardware architecture of a navigation system according to an embodiment of the invention.
[0049] As illustrated by [Fig.l], according to one embodiment, the navigation system SYS proposed for a vehicle comprises at least the following elements: a set of sensors SENS; a navigation device APP; and a guidance module CMD.
[0050] The navigation device APP is configured to determine, from the data from the set of sensors SENS, navigation data IN_NAV_CMD of the vehicle.
[0051] The CMD guidance module is configured to guide the vehicle based on the IN_NAV_CMD navigation data provided by the APP device.
[0052] According to one embodiment, the SYS system is embedded in a vehicle, for example in a land vehicle: car, truck, train, etc., or in a marine vehicle: boat, frigate, or even in an air vehicle: an aircraft, a helicopter, an airplane, a drone, etc. In particular, the SYS system is, according to an alternative embodiment, embedded in an aircraft.
[0053] In the context of the invention, navigation data of a vehicle designates data relating to the position, and / or the movement of the vehicle and includes, for example, geographical coordinates (e.g. latitude, longitude, altitude), a speed, a heading. The navigation data can be defined absolutely with respect to the terrestrial reference frame, or relatively with respect to a reference position (e.g. a landing strip). For example, a relative position of the vehicle at a given time determined by the navigation device APP can include one or more coordinates from the following set: an azimuth, a vertical distance, a longitudinal distance, and a lateral distance defined relative to a reference position.
[0054] As illustrated by [Fig. 1], according to one embodiment, the set of sensors SENS comprises at least one of the following sensors: at least one inertial measurement unit IMU; at least one GPS satellite positioning module; at least one BARO altimeter; a VISION sensor (hereinafter referred to as a computer vision device or sensor); at least one odometer; a Pitot probe; and a magnetometer.
[0055] The inertial measurement unit IMU provides OUT_IMU data, also called inertial data. According to one embodiment, the inertial data OUT_IMU comprise, for a plurality of measurement instants, data relating to the specific force Fs (i.e. the sum of the external forces other than gravitational forces divided by the mass) and the angular velocity Q of the vehicle. Typically, the inertial measurement unit IMU comprises: three gyrometers measuring the three components of the angular velocity Q (rates of variation of the roll, pitch and yaw angles); and three accelerometers measuring the three components of the specific force Fs.
[0056] The GPS satellite positioning module provides OUT_GPS navigation data. According to one embodiment, the OUT_GPS navigation data comprise, for a plurality of measurement times, a position Pos and a speed Vel of the vehicle. Typically, the GPS satellite positioning module provides an absolute position Pos relative to the terrestrial reference frame comprising one or more coordinates from the following set: latitude, longitude; and altitude. According to one embodiment, the satellite positioning module complies with the “Global Positioning System”, more commonly referred to by the acronym GPS. However, within the scope of the invention, other embodiments could also be envisaged in which all types of GNSS modules (acronym for “Geolocation and Navigation by a Satellite System”) would be used, such as Galileo, Glonass modules, etc.
[0057] The BARO altimeter provides OUT_BARO data as output, called altimetric data. The BARO altimeter is, according to one embodiment, a barometric altimeter. In particular, the OUT_BARO altimetric data are, for a plurality of measurement times, representative of the altitude Alt of the vehicle or of variations in altitude of said vehicle.
[0058] The computer vision sensor VISION (also referred to as a “computer vision device”) provides OUT_VIS data as output. According to one embodiment, the sensor VISION comprises or is configured to communicate with: a recording medium DB; and an image acquisition device CAM. The recording medium DB, for example a database, comprises the positions (i.e. geographic coordinates) of a plurality of AMER reference terrestrial points (hereinafter referred to as landmarks) as well as information relating to the graphical representations of the AMER reference terrestrial points. For example, the reference terrestrial points may be a landing runway, a navigation light, an approach slope indicator ("Precision Approach Path Indicator" in English), etc. The CAM image acquisition device comprises at least one camera on board the vehicle and having an electromagnetic radiation sensor whose wavelengths belong to the visible light and / or infrared spectrum.According to one embodiment, the CAM image acquisition device comprises at least one camera from among the following: a visible light camera; a near-infrared camera, a short-wavelength infrared camera, a medium-wavelength infrared camera, and a long-wavelength infrared camera. The CAM image acquisition device is configured to acquire a plurality of images for a plurality of measurement times.
[0059] The computer vision sensor VISION takes as input: the images acquired by the image acquisition device CAM; and the navigation data OUT_LOC_VIS from the navigation module LOC_VISION, in particular the position of the vehicle. The sensor VISION is, according to one embodiment, configured to: detect the terrestrial reference points AMER in the acquired images; and determine the observed relative positions of the detected terrestrial reference points AMER relative to the vehicle from said acquired images. The sensor VISION is further configured to, according to one embodiment, determine estimated relative positions of the detected terrestrial reference points AMER relative to the vehicle from a position of the vehicle determined by the navigation module LOC_VISION and known positions of the terrestrial reference points AMER.According to one embodiment, the OUT_VIS data provided by the VISION sensor comprises, for a plurality of measurement times, differences ax, ay between the observed and estimated relative positions of the terrestrial reference points AMER relative to the vehicle. Typically, the relative position (observed or estimated) of a landmark relative to the vehicle is defined by two angles - a lateral angle and a vertical angle - characterizing the line of sight of the landmark relative to the longitudinal axis of the vehicle.
[0060] According to one embodiment, to detect a reference terrestrial point in an image, the VISION sensor is configured to select in this image a region of interest (i.e. a portion of this image) and detect the reference terrestrial point in this region of interest. In particular, the coordinates of the region of interest are defined completed from: the known position of the terrestrial reference point; the position of the vehicle determined by the LOC_VISION navigation module; and information provided by the LOC_VISION navigation module relating to the protection radius of the determined position of the vehicle (i.e. the probability that the position error is less than the protection radius is greater than a defined value, in particular very close to 1). Using a region of interest makes it possible to restrict the portion of the image to be processed to detect a landmark and thus makes it possible to reduce the hardware and software resources (e.g. processing time, memory, etc.) necessary for detecting a landmark in acquired images.
[0061] Obviously, the set of sensors SYS can comprise one or more of each of the IMU, GPS, BARO, VISION sensors as described above.
[0062] As illustrated by [Fig. 1], the navigation device APP comprises, according to one embodiment: a navigation module LOC_GPS (called first navigation module); a navigation module LOC_VISION (called second navigation module); and a control module SWITCH. The navigation modules LOC_GPS and LOC_VISION respectively provide navigation data OUT_LOC_GPS (called first navigation data) and navigation data OUT_LOC_VIS (called second navigation data). It should be noted that the navigation modules LOC_GPS and LOC_VISION produce the navigation data OUT_LOC_GPS and OUT_LOC_VIS independently and, more particularly, simultaneously (i.e. in parallel).According to one embodiment, the navigation data OUT_LOC_GPS and OUT_LOC_VIS respectively comprise, for a plurality of measurement times, a position Pos, a speed Vel and a direction Cap of the vehicle and associated protection radii PL.
[0063] It should be noted that the parallel use of the two separate navigation modules LOC_GPS and LOC_VISION makes it possible to improve the integrity of the vehicle's SYS navigation system and thus the resilience of the SYS system with respect to failures of the sensors used for navigation.
[0064] The LOC_GPS navigation module determines the OUT_LOC_GPS navigation data from the data from the IMU inertial measurement unit, the GPS satellite positioning module, and the BARO altimeter.
[0065] As illustrated by [Fig. 1], according to one embodiment, the navigation module LOC_GPS comprises: an inertial unit NAV_IMU_GPS; and a Kalman filter KAL_FLT_GPS. The inertial unit NAV_IMU_GPS is configured to integrate over time the specific force Fs and angular velocity Q data produced by the inertial measurement unit IMU and thus determine navigation data Pos, Vel, Cap of the vehicle. The Kalman filter KAL_FILT_GPS determines, from the data from the GPS and BARO sensors, corrections ôPos, ôVel, ôCap, ôFs, and ôQ to be applied to the inertial unit NAV_IMU_GPS. The OUT_LOC_GPS navigation data provided as output thus correspond, according to one embodiment, to the navigation data determined by the inertial unit NAV_IMU_GPS corrected (i.e. recalibrated) from the data from the Kalman filter KAL_FLT_GPS. In other words, the Kalman filter KAL_FLT_GPS makes it possible to compensate for the inertial navigation drift (i.e. recalibrate) from the data from the GPS and BARO sensors.
[0066] It should be noted that, when the GPS satellite positioning module is not functional (e.g. unavailable, broken down, faulty, unusable), the LOC_GPS navigation module continues to output the OUT_LOC_GPS navigation data. However, in this case, the LOC_GPS navigation module cannot use the data from the GPS satellite positioning module to compensate for the drift (i.e. recalibration) of the NAV_IMU_GPS inertial unit. The same is true when the BARO altimeter is not available.
[0067] The LOC_VISION navigation module determines the OUT_LOC_VIS navigation data from the data from the IMU inertial measurement unit, the GPS satellite positioning module, the BARO altimeter and the VISION sensor.
[0068] As illustrated by [Fig.l], the LOC_VISION navigation module has, according to one embodiment, an architecture similar to the LOC_GPS navigation module. According to this embodiment, the LOC_VISION navigation module comprises: an inertial unit NAV_IMU_VIS; and a Kalman filter KAL_FLT_VIS. The OUT_LOC_GPS navigation data provided as output thus correspond, according to one embodiment, to the navigation data determined by the inertial unit NAV_IMU_VIS to which the corrections determined by the KAL_FILT_VIS filter are applied from the data from the GPS, BARO and VISION sensors. In other words, the KAL_FLT_GPS Kalman filter makes it possible to compensate for the inertial navigation drift (i.e. recalibration) from the data from the GPS, BARO and VISION sensors.
[0069] Within the framework of the invention, other embodiments could also be envisaged according to which one or both of the navigation modules LOC_GPS and LOC_VISION respectively use a Kalman filter (e.g. an extended Kalman filter) taking as input the data from all or part of the sensors of the SENS set and producing said navigation data as output.
[0070] It should be mentioned that the LOC_VISION navigation module uses, to recalibrate the NAV_IMU_VIS inertial unit, the data from the other GPS, BARO, VISION sensors when these data are available. According to one example, the VISION sensor cannot be used by the LOC_VISION navigation module for recalibrate the NAV_IMU_VIS inertial unit only after detecting a landmark. In another example, the LOC_VISION navigation module does not use data from the GPS satellite positioning module when the GPS module is faulty or unusable.
[0071] However, it is important to emphasize that the navigation data determined at a given instant are a function of the navigation data determined at previous instants. Indeed, the inertial units NAV_IMU_GPS and NAV_IMU_VIS integrate over time the specific force Fs and angular velocity Q data produced by the inertial measurement unit IMU to determine navigation data OUT_LOC_GPS and OUT_LOC_VIS. Also, small errors in measuring the specific force Fs and angular velocity Q are integrated over time by the inertial units and thus lead to speed and position errors that increase over time (i.e. drift of the inertial navigation). Consequently, using a sensor at a given instant to recalibrate an inertial unit makes it possible to improve the accuracy of the navigation data determined at later instants.
[0072] Let us suppose for example that during a first period, the LOC_VISION navigation module uses the data from the GPS module to compensate for the drift of the NAV_IMU_VIS inertial unit. Then, during a second subsequent period, the GPS satellite positioning module is no longer available. During the second period, although the GPS module is no longer available, the LOC_VISION navigation module determines OUT_LOC_VIS navigation data that is more precise than a navigation module that never uses data from a GPS module. Indeed, the LOC_VISION navigation module benefits during the second period from the recalibration of the inertial unit during the first period.
[0073] The control module SWITCH receives the navigation data OUT_LOC_GPS and OUT_LOC_VIS respectively produced by the navigation modules LOC_GPS and LOC_VISION and provides the guidance module CMD with navigation data IN_NAV_CMD. According to one embodiment, the control module SWITCH provides the guidance module CMD with either the navigation data OUT_LOC_GPS or the navigation data OUT_LOC_VIS. In particular, the control module SWITCH is configured to select the navigation data to be provided depending on the availability (i.e. functional or non-functional) of the GPS satellite positioning module, this embodiment being detailed below with reference to FIGS. 2A and 2B.
[0074] Figures 2A and 2B represent, schematically and in the form of a flowchart, steps of a navigation method according to one embodiment of the invention.
[0075] As illustrated by Figures 2A and 2B, and according to one embodiment of the invention, the proposed navigation method comprises at least one of the following steps S10 to S50 implemented by the proposed navigation system SYS. According to a particular embodiment, steps S10 to S50 are implemented in a chronological order as described below.
[0076] During step S10, the navigation module LOC_GPS determines navigation data OUT_LOC_GPS of the vehicle from the data from the inertial measurement unit IMU, the GPS satellite positioning module, and the BARO altimeter.
[0077] During step S20, the navigation module LOC_VISION determines navigation data OUT_LOC_VISION of the vehicle from the data from the inertial measurement unit IMU, the GPS satellite positioning module, the BARO altimeter, and the VISION computer vision sensor. According to one embodiment, step S20 comprises sub-steps S21 to S24 detailed below with reference to [Fig.2B].
[0078] Steps S10 and S20 can be performed simultaneously, one before the other or vice versa. According to a particular embodiment, steps S10 and S20 are performed in parallel.
[0079] As mentioned previously, if one of the GPS, BARO, or VISION sensors is not functional (e.g. unavailable, broken, faulty, unusable), the LOC_GPS and LOC_VISION navigation modules continue to output the OUT_LOC_GPS and OUT_LOC_VIS navigation data. However, in this case, the LOC_GPS and LOC_VISION navigation modules cannot use the data from the non-functional sensor to compensate for the drift (i.e. recalibration) of the NAV_IMU_GPS and NAV_IMU_VIS inertial units.
[0080] During step S30, the SWITCH control module determines whether the GPS satellite positioning module is functional (i.e. available and usable). For information purposes, the GPS satellite positioning module may not be functional (i.e. faulty, broken down) due to a failure of one of the satellites in the GPS constellation, or a failure of the onboard GPS module itself. During step S30, the SWITCH control module implements, according to one embodiment, a step of detecting a failure (i.e. failure) of the GPS satellite positioning module to determine whether the GPS satellite positioning module is functional.
[0081] During step S40, if, and only if, it has been determined in step S30 that the GPS satellite positioning module is functional, the control module SWITCH provides the navigation data OUT_LOC_GPS to the guidance module CMD of the vehicle.
[0082] During step S50, if it has been determined in step S30 that the posi module If GPS satellite operation is not functional (GPS module is unavailable, faulty, broken or not usable), the SWITCH control module provides OUT_LOC_VIS navigation data to the vehicle's CMD guidance module.
[0083] Following step S50, the navigation system implements, according to one embodiment, steps S10 and S20 previously detailed. Thus, the proposed navigation method comprises, according to this embodiment, several iterations of steps S10 to S50 described above.
[0084] As illustrated by [Fig.2B], step S20 comprises, according to one embodiment, at least one of steps S21 to S24 detailed below with reference to [Fig.2B] and implemented by the proposed navigation system SYS.
[0085] During step S21, the VISION sensor detects at least one terrestrial reference point AMER in images acquired by the image acquisition device CAM.
[0086] According to a particular embodiment, to detect a terrestrial reference point AMER in an image, the VISION sensor implements the following steps. The VISION sensor selects a portion of this image (i.e. a region of interest), the coordinates of the image portion being determined from: the known position (e.g. geographic coordinates) of the terrestrial reference point AMER; the position of the vehicle determined by the LOC_VISION navigation module; and information relating to the accuracy of the position of the vehicle provided by the LOC_VISION navigation module (i.e. the protection radius). Following the selection of the image portion, the VISION sensor detects the terrestrial reference point AMER in the image portion.
[0087] During step S22, the VISION sensor determines an observed relative position POS_AMER_OBS of the detected reference terrestrial point AMER relative to the vehicle from the acquired images.
[0088] During step S23, the VISION sensor determines an estimated relative position POS_AMER_EST of the detected reference terrestrial point AMER relative to the vehicle from a position of the vehicle provided by the navigation module LOC_VISION and a known position of the reference terrestrial point AMER.
[0089] During step S24, the VISION sensor provides the navigation module LOC_VISION with the difference ax, ay between the observed relative position POS_AMER_OBS and the estimated relative position POS_AMER_EST of the reference terrestrial point AMER relative to the vehicle; and the navigation module LOV_VISION determines navigation data OUT_LOC_VIS in particular from this difference ax, ay.
[0090] [Fig.3] schematically represents an example of software and hardware architecture of a navigation system according to an embodiment of the invention.
[0091] As illustrated by [Fig.3], according to one embodiment, the navigation device The proposed APP comprises: at least one processing unit or processor PROC; and at least one memory MEM.
[0092] The APP device has, according to one embodiment, the hardware architecture of a computer and comprises, as such, a processor PROC, a random access memory, a read-only memory MEM, and a non-volatile memory. The memory MEM associated with the APP device constitutes an information or recording medium in accordance with the invention, readable by a computer and by the PROC processor, on which a PROG computer program in accordance with the invention is recorded. The PROG computer program comprises instructions for carrying out steps of a method in accordance with the invention and implemented by the APP device, when the PROG computer program is executed by the PROC processor.
[0093] As illustrated by [Fig.3], according to one embodiment, the APP device has of a COM communication module configured to communicate with at least one of the following elements: one or more sensors of the SENS sensor set; and the CMD guidance module. Obviously, no limitation is attached to the nature of the communication interfaces between the proposed APP device and respectively: the sensors of the SENS set; and the CMD guidance module, which may be wired or wireless, and may implement any protocol known to those skilled in the art (Ethernet, Wi-Fi, Bluetooth, 3G, 4G, 5G, 6G, etc.).
[0094] According to one embodiment (not shown), the VISION sensor (also called a computer vision device) has the hardware architecture of a computer and comprises, as such, a processor, a random access memory, a read-only memory, and a non-volatile memory. In the embodiment described here, the memory associated with the VISION sensor constitutes an information medium, readable by a computer and on which a computer program is recorded. This computer program comprises instructions for carrying out steps of a method according to the invention and implemented by the VISION sensor, when this computer program is executed by a processor.
[0095] The proposed SYS navigation system makes it possible to accurately determine the navigation data of a vehicle while guaranteeing a high level of integrity, allowing the SYS navigation system to be integrated into a critical system such as an aircraft.
[0096] In particular, the proposed SYS navigation system makes it possible to ensure a high level of integrity while significantly relaxing the constraints of integrity time risk on the VISION computer vision sensor. In other words, the proposed SYS navigation system makes it possible to ensure a high level of integrity, even with a VISION computer vision sensor of low maturity.
[0097] Let us take as an example a reference navigation system comprising a single navigation module using data from an inertial measurement unit, a satellite positioning module and a computer vision sensor. Such a navigation system does not ensure a high level of integrity and could not be integrated into a critical system. Indeed, the hourly integrity risk conditions to be verified for the computer vision sensor are not achievable with this reference system, due to the lack of maturity of the computer vision sensor and the computer vision techniques.
[0098] In comparison with the aforementioned reference system, the proposed navigation system SYS has two navigation modules LOC_GPS and LOC_VISION and conditions the use of the VISION computer vision sensor to situations for which the GPS satellite positioning module is not available. Thus, the proposed SYS navigation system and, more particularly, the architecture of the APP navigation device make it possible to significantly relax the constraints on the hourly integrity risk to be verified for the VISION computer vision sensor.
[0099] The term module can correspond to a software component as well as to a hardware component or a set of hardware and software components, a software component itself corresponding to one or more computer programs or sub-programs or more generally to any element of a program capable of implementing a function or a set of functions as described for the modules concerned. In the same way, a hardware component corresponds to any element of a hardware assembly capable of implementing a function or a set of functions for the module concerned (integrated circuit, smart card, memory card, etc.).
[0100] It should be noted that the order in which the steps of a method according to the invention are carried out, in particular with reference to the attached drawings, constitutes only an example of an embodiment without any limiting character, variants being possible.
[0101] A person skilled in the art will understand that the embodiments and variants described above constitute only non-limiting examples of implementation of the invention. In particular, a person skilled in the art will be able to envisage any adaptation or combination of the embodiments and variants described above in order to meet a very specific need.
Claims
Claims
1. A method of navigation for a vehicle, said method comprising steps of: - determination (S 10) by a first navigation module (LOC_GPS) of first navigation data of said vehicle (OUT_LOC_GPS) from data (0UT_IMU, OUT_GPS) from an inertial measurement unit (IMU) and a satellite positioning module (GPS); and - determination (S20) by a second navigation module (LOC_VISION) of second navigation data of said vehicle (OUT_LOC_VIS) from: data (OUT_IMU, OUT_VIS) from the inertial measurement unit (IMU), and from images acquired by said vehicle; and further from data (OUT_GPS, OUT_BARO) from said satellite positioning module (GPS) and / or from an altimeter (BARO).
2. Method according to claim 1, wherein: - the first navigation module (LOC_GPS) and the second navigation module (LOC_VISION) use the data (OUT_GPS) from the satellite positioning module (GPS) when the satellite positioning module (GPS) is operational; - said method comprises steps of: • if said satellite positioning module (GPS) is operational (S30), providing (S40) said first navigation data (OUT_LOC_GPS) to a guidance module (CMD) of said vehicle; and • otherwise, providing (S50) said second navigation data (OUT_LOC_VIS) to said guidance module (CMD) of said vehicle; and - said method comprises several iterations of said steps of determining (S 10, 20) and providing (S40, S50).
3. Method according to claim 1 or 2, wherein the first (LOC_GPS) and second navigation modules (LOC_VISION) com- respectively take an inertial unit (NAV_IMU_VIS, NAV_IMU_GPS) and a Kalman filter (KAL_FILT_GPS, KAL_FILT_VIS) to determine (S 10, S20) said first and second navigation data (OUT_LOC_GPS, OUT_LOC_VIS).
4. Method according to one of claims 1 to 3, comprising steps of: - detecting (S21) at least one terrestrial reference point (AMER) in said acquired images; - determining (S22) an observed relative position (POS_AMER_OBS) of said at least one detected terrestrial reference point (AMER) with respect to said vehicle from said acquired images; - determining (S23) an estimated relative position (POS_AMER_EST) of said at least one detected terrestrial reference point (AMER) with respect to said vehicle from a position of said vehicle determined by the second navigation module (LOC_VISION) and a known position of said at least one terrestrial reference point (AMER);and - determination (S24) of said second navigation data (OUT_LOC_VIS) from the difference (ax, ay) between the observed (POS_AMER_OBS) and estimated (POS_AMER_EST) relative positions of said at least one terrestrial reference point (AMER) relative to said vehicle.;
5. Method according to claim 4, wherein said step of detecting (S21) at least one terrestrial reference point (AMER) in the acquired images comprises steps of: - selecting a portion of at least one acquired image, the coordinates of said portion being determined from a known position of said at least one terrestrial reference point (AMER), from a position of said vehicle determined by the second navigation module (LOC_VISION) and from information relating to the accuracy of said determined position of said vehicle provided by the second navigation module (LOC_VISION); and - detecting said at least one terrestrial reference point (AMER) in said portion of said at least one image acquired.
6. Navigation device (APP) for a vehicle, said device (APP) comprising: - a first navigation module (LOC_GPS) configured to determine (S 10) first navigation data of said vehicle (OUT_LOC_GPS) from data (0UT_IMU, OUT_GPS) from an inertial measurement unit (IMU) and a satellite positioning module (GPS); and - a second navigation module (LOC_VISION) configured to determine (S20) second navigation data of said vehicle (OUT_LOC_VIS) from: data (OUT_IMU, OUT_VIS) from the inertial measurement unit (IMU) and images acquired by said vehicle; and further from data (OUT_GPS, OUT_BARO) from said satellite positioning module (GPS) and / or an altimeter (BARO).
7. Navigation system (SYS) for a vehicle, said system (SYS) comprising: - a navigation device (APP) according to claim 6; - an inertial measurement unit (IMU); - a satellite positioning module (GPS); and - an image acquisition device (CAM).
8. Navigation system (SYS) according to claim 7, comprising a computer vision device (VISION) configured to determine at least one position of the vehicle from the images acquired by the image acquisition device (CAM).
9. Navigation system (SYS) according to claim 7 or 8, comprising a guidance module (CMD) configured to guide said vehicle from navigation data (IN_NAV_CMD) determined by said navigation device (APP).
10. Vehicle comprising a navigation system (SYS) according to one of claims 7 to 9.
11. Computer program (PROG) comprising instructions for the implementing the steps of a method according to any one of claims 1 to 5, when said computer program (PROG) is executed by at least one processor (PROC).
12. Computer-readable information medium (MEM) comprising a computer program (PROG) according to claim 11.