FR2950702A1 - METHOD AND DEVICE FOR DYNAMICALLY LOCATING A MOBILE - Google Patents

Abstract

The method of dynamically locating a rigid structure mobile is implemented by a hybrid location device comprising a radiolocation receiver connected to a receiving antenna having a phase center and a triaxial inertial unit having a central reference point. The method comprises a step of correcting (236) each raw pseudo-distance ρ (t, i), conventionally determined and associated with a distinct satellite, to a corresponding pseudo-distance corrected ρ (t, i), a function of the raw pseudo-distance ρ (t, i) of current inertial information, and the elevation angle under which the satellite is seen from the phase center.

Description

The invention relates to a method for measuring the dynamic positioning of a mobile, in particular an automobile, an airplane, a ship or a maritime buoy, implemented using a simple hybrid device that combines a receiver, provided with a radiolocation beacon signal receiving antenna, and a triaxial inertial unit. Traditionally, radiolocation beacon signals are provided by satellite-based global positioning systems such as Global Positioning System (GPS), GLONASS, and GALILEO. When only one GPS signal receiving antenna is used, it is known that only position, time and speed information of a point of the mobile can be determined but not guidance or attitude information of the mobile. .

Thus, when it is necessary to take into account variations in the attitude of the mobile, several GPS reception antennas on the mobile are required and able, from the corresponding received signals, to determine the attitude in-formations. However, this multi-antenna configuration does not make it possible to obtain high precision positioning information when the mobile undergoes large and rapid variations of attitude, and when the applications also require mobile position measurement frequencies higher than the frequencies. between 1 Hz and 10 Hz. Indeed, the GPS system has a dynamic response too low compared to the dynamic variations of attitude experienced by the mobile. To overcome these drawbacks, it is known to integrate in a hybrid system, comprising at least one radiolocation receiver, inertial attitude sensors or gyrometers, for example sensors of SIAS type (English name of "Strap down Inertial Sensors"). ") Mounted on a linked-component inertial center or gyroscopic stabilized gimbal platform, in a global satellite positioning system and to correct the position of the mobile provided by the radiolocation signals with the information from the sensors. attitude of the inertial unit.

However, if the inertial unit is able to provide accurate and continuous attitude information in the form of angular velocities at a high frequency greater than 50 Hz, in many applications, this accuracy is degraded by noise that is difficult to filter and this degradation also significantly affects the accuracy of the mobile position information. The technical problem is to improve the positioning accuracy of a mobile provided by a hybrid location system when the mobile undergoes high frequency attitude variations. For this purpose, the subject of the invention is a method for dynamically locating a mobile having a rigid structure by a hybrid localization device comprising: a radiolocation receiver, connected to a reception antenna having a phase center (G) associated with a frequency fi, the receiving antenna being fixed relative to the structure of the mobile, and a triaxial inertial unit having a reference point (P) center of a reference mark (p) of the inertial unit, the center (P) being fixed with respect to an orthonormal reference of the structure of the mobile, comprising the steps of receiving by the radiolocation receiver and with respect to the phase center of the receiving antenna, at a predetermined observation time a plurality of radiolocation signals each transmitted at the frequency f1 by a transmitter of a different satellite, visible from the mobile, processing the received signals and determining conventional pGPS (t, i) conventional raw pseudo-range information observed at time t, providing the radiolocation receiver to a raw data memory the conventional raw data of pseudo-distances pGPS (t, i) observed at the instant t, to supply the inertial unit with the raw data memory at the instant t of observation current inertial information associated with the instant t of the mobile with respect to a local geodetic reference mark, characterized in that it comprises the steps of: first, for each fixed satellite (Si), determining the elevation angle (El (t, i)) under which the satellite (Si) is seen from the center of phase (G ) of the receiver antenna according to the global positioning coordinates of the satellite (Si) and the overall position of the phase center (G), the overall position of the phase center (G) being determined according to the pseudo-distances classical pGPS (t, i) brutes to the satellites, correct each pseudo-raw distance pGPS (t, i) in a corrected pseudo-distance pc01. (t, i) corresponding function of the raw pseudo-distance pGPS (t, i), current inertial information, elevation angle (El (t, i)), then determine the geodesic local positioning of the mobile in the local geodesic locator-II following a conventional multi-latency process from the corrected pseudo-distances pc0 (t, i) as new raw data, each of the corrected pseudo-distances corresponding to a different satellite (Si). According to particular embodiments, the method comprises one or more of the following characteristics: the inertial unit is able to determine from three gyrometers Eulerian angles cp, 8, ip, respectively called roll, pitch and yaw, of transforming the directions of the b-mark bound to the mobile in directions of the local geodetic marker-I and determining from a local vertical accelerometer a displacement dth (t) in translation of the mobile according to the vertical of the local geodesic mark, and the inertial information includes the transformation angles cp, 8, qi at the instant t, the displacement dth (t) in translation of the mobile according to the local vertical and the coordinates bX, by, bZ of a vector of the lever arm ( Bb) in the reference-b of the mobile, the leverage vector (Bb) being defined as the vector connecting the reference point (P) of the inertial unit to the center of phase (G) of the antenna of reception, - the corrected pseudo-distance satisfies the equation: p, 20, (t, i) = i-'1 (t, i) + dh2 (t) + 2 sgn (dh (t)) pGps (t, i) dh (t) sin (EL (t, i)) in which sgn (.) denotes the sign function and dh (t) satisfies the equation dh (t) = 9 (ùbx cos 0 ùb, sin ço sin 0 8) + dth (t) - the method comprises the steps of determining for each satellite (Si) the angle of (Az (t, i) ) of the satellite seen by the phase center (G) of the receiving antenna (18) with respect to the direction of the geographical north, for each satellite (Si), correcting the conventional pseudo-gross distance (pGPS (t, i )) associated with a pseudo-distance corrected (pc0 (t, i)) corresponding to the function of the classical pseudo-distance (pGps (t, i)), current inertial information, elevation angle ( El (t, i)) and the angle of (Az (t, i)) of the satellite (Si) seen by the phase center (G) of the antenna relative to the direction of the north io, the inertial unit being able to determine from three gyrometers transformation angles cp, 8, qi of the directions of the reference-b bound to the mobile in directions of the local geodesic landmark II, and the current inertial information including the angles transforming cp, 8, qi at time t, coordinates of a lever arm vector (Bb) in the b-mark of the mobile, bX, by, bZ, the lever arm vector (Bb ) being defined as the vector connecting the reference point (P) of the inertial unit to the phase center (G) of the receiving antenna, - the corrected pseudo-distance satisfies the equation: p o .. (t, i) = [pG2Ps (t, i) cOS2 E1 (t, i) + d2 (t) 2pGPS (t, i) d1 (t) cos (EL (t, i) cos c1) (t, i)] / cOS2 El (t, i) In which d1 denotes a displacement satisfying the equation dl (t) = [(b, (ùcos 9 sin tv + cos cos tv) + by (ùcos v sin tv + sin v sin O cos yr ù cos cos yr + sin v sin O sin yr) + bz q sin 9 sin yr + sin q sin tv ù cos q sin 9cos yr)] yr And c (t, i) denotes an angle satisfying the equation: c (t, i) = arccos (dl (t) / 2bx) Δt (t, i) - the method comprises the steps of; in a step, first determine a vertical displacement dh (t) of the observed mobile moment t according to the coordinates of the lever arm B, bx, by, bz, Eulerian angles cp, 8, ip, and displacement vertically in translation dth (t) according to the equation: dh (t) = 8 (ûbx cos 8 û b, sin sin 8 û bz cos sin 8) + çp (by cos çocos 8 ûbz sin çocos 8) + dth (t ) and determine the vertical corrected pseudo-distance p orr (t, i) associated with the satellite (Si) as a function of the vertical displacement (dh (t)) of the mobile determined and observed at time t, of the conventional pseudo-distance pGPS (t, i), and the elevation angle El (t, i) of the satellite (Si) seen by the phase center (G) according to the expression: p, 2, (t, i) = pG2PS (t, i) + dh2 (t) + 2 sgn (dh (t)) pGps (t, i) dh (t) sin (EL (t, i)) in which sgn (.) designates the sign function; in a step, the calculator first calculates a horizontal displacement dl (t) of the observed mobile time t function of the coordinates of the lever arm B, bX, by, bZ, Eulerian angles cp, 8, qi following the equation:

dl = [(b1x (û cos 9 sin ty + cos 9 cos ty) + b1 (ûcos sin y / + sin qsin Gcos y / ûcos qcos y / + sin qsin Gsin yi) + b1 (sin gcostyucosgsineinty + singsintyucosgsin9costy)] ty then, in the same step, determine the angle (1) (t, i) formed between the direction of the horizontal projection of the line of sight (G) -satellite (Si) and the direction of displacement horizontal dl (t) of the mobile, as a function of the horizontal displacement dl (t), the yaw angle ip, the component bX of the lever arm Bb, and the angle of the satellite Az (t, i) seen by the phase center (G) of the antenna with respect to the direction of the geographic North, as follows: c (t, i) = arccos (dl (t) 12bx) û ty ù Az (t , i) then, in the same step, determining the pseudo-corrected horizontal distance pci0 (t, i) associated with the satellite (Si) as a function of the horizontal displacement dl (t) of the mobile determined at time t, of the pseudo -distance classical pGPS (t, i) determined in a cl assigne in an overall positioning system between the phase center (G) and the satellite, the elevation angle E1 (t, i) of the satellite (Si) seen by the phase center (G) and the angle t (t, i), according to the expression: p, 102Y (t, i) = [p, 2PS (t, i) cos 'E1 (t, i) + d1' (t) 2pGps (t, i) dl (t) cos (EL (t, i) cos 1 (t, i)] cos El (t, i) in a step (236), determine a general pseudo-distance p ,, (t, i) corrected for the pseudo-vertically corrected distance p ôYY (t, i) and the horizontally corrected pseudo-distance pc10, 7 (t, i), each associated with the same satellite (Si); the corrected pseudo-general distance pc0 (t, i) is a function of the classical pseudorange pGPS (t, i), the vertically corrected pseudo-distance p ôYY (t, i), and the pseudo-distance corrected horizontally pci0 (t, i), each associated with the same satellite Si according to the expression: PoYY (t, i) = PGPS (t, i) + (PioYY (t, i) ùPGPS (t, i)) + (P0YY (t , i) ùPGPS (t, i)) - the corrected pseudo-general distance pc0 (t, i) is an average of the vertically corrected pseudo-distance p ÔYY (t, i) and the pseudo-horizontally corrected distance pci0 ( t, i), the average being chosen from the set constituted by the average algebraic, the mean barycentric, the geometric mean; the radiolocation receiver, connected to a reception antenna, is bi-frequency adapted to receive signals at a first frequency f 1 and at a second frequency f 2 and comprises two phase centers (G 1) and (G 2) respectively associated with the first frequency fi and at the second frequency f2; and the phase center (G) is the equivalent phase center (Geq) obtained by reduction of the phase centers (G1) and (G2); the method comprises the step of: for each satellite (Si), determining the angle of (Az (t, i)) of the satellite (Si) seen by the receiving antenna with respect to the North direction geographical, correcting the equivalent phase center (Geq) a new equivalent phase center Geq (Si) depending on the elevation angle (El (t, i)) under which the satellite (Si) is seen from the antenna of reception, of the angle of (Az (t, i)) of the satellite (Si) seen by the receiving antenna with respect to the direction of the geographic North, to determine the coordinates of a new lever arm B ( Si) for use in calculating the corrected pseudo-distance pc0 (t, i) associated with the satellite (Si); the method comprises a decision step of the subsequent use or not of the current inertial data, acquired in the step, in the step of correcting the conventional pseudo-distance raw data pGPS (t, i) as a function of the logical state of a reliability parameter (fiab (t)) of the inertial information, a function of time; the method comprises the steps of determining the angle of (Az (t, i)) of the satellite (Si) seen by the receiving antenna with respect to the direction of the geographic north, and correcting the so-called geometric effect English "windup phase" from the knowledge of the relative position of the receiving antenna with respect to the geographic North or the angle of (Az (t, i)).

The invention also relates to an instruction recording medium, characterized in that it comprises instructions for the execution of a method as defined above, when these instructions are executed by an electronic computer. The invention also relates to a device for dynamic location of a mobile comprising: a radiolocation receiver, a reception antenna connected to the radiolocation receiver, and having a phase center (G) associated with a frequency fi, l ' receiving antenna being fixed relative to the structure of the mobile, a triaxial inertial unit having a reference point (P) center of a reference mark (p) of the inertial unit, the center (P) being fixed relative to an orthonormal reference (b) of the mobile structure, and a raw data memory, the receiver being able to receive with respect to the phase center (G) of the receiving antenna, at a predetermined observation time t a a plurality of radiolocation signals, each of which is transmitted at the frequency f1 by a transmitter of a different satellite, visible from the mobile, for processing the received signals, to classically determine raw information s conventional pseudo-distances pGPS (t, i) observed at time t, and to provide to a raw data memory the conventional raw information pseudo-distances pGPS (t, i) observed at time t, the an inertial unit capable of supplying the raw data memory at the observation instant t with current inertial information associated with the instant t of the mobile with respect to a local geodetic reference mark, characterized in that it comprises a computer capable of : first, for each fixed satellite (Si), determine the elevation angle (EI (t, i)) under which the satellite (Si) is seen from the phase center (G) of the receiver antenna according to the global positioning coordinates of the satellite (Si) and the overall position of the phase center (G), the overall position of the phase center (G) being determined according to the conventional pseudo-gross distances (pGPS (t, i)) associated with the satellites, correct each pseudo-gross distance (pGPS (t, i)) in a corrected pseudo-distance pc0 (t, i) corresponding to the function of the pseudo-gross distance (pGps (t, i)), current inertial information, elevation angle (EI (t, i)) )), and then, determine the geodesic local positioning of the mobile in the local geodesic locator-I following a conventional multi-latency process from the corrected pseudo-distances pc0 (t, i) as new raw data, each of pseudo-corrected distances corresponding to a different satellite (Si). The invention also relates to a mobile including an automobile, an aircraft, a ship, a marine buoy characterized in that it comprises a positioning device as defined above. The invention will be better understood on reading the description of an embodiment which will follow, given solely by way of example and with reference to the drawings in which: FIG. 1 is a view of a section of a marine buoy on which is mounted a positioning device according to the invention, - Figure 2 is a view of a set of reference marks to which are determined the position coordinates and / or attitude of the buoy of 1, FIGS. 3, 4 and 5 are views of definition of the Eulerian coordinates of the buoy's attitude relative to a mark of the buoy described in FIG. 2; FIG. 6 is a block diagram FIG. 7 is a flow diagram of a positioning device operating with a GPS radiolocation system; FIG. 7 is a flowchart of a buoy positioning method; FIG. 8 is a geometrical representation of the vertical displacement of the buoy and the pseudo- d istance corrected vertically in a geodesic local coordinate system; - Figure 9 a geometric representation of horizontal displacement and the pseudo-distance corrected horizontally in the local geodesic coordinate system; FIG. 10 is a geometric representation of the angle formed between the direction of horizontal displacement of the buoy and the aiming direction of the phase center of the antenna of the receiver on a satellite; FIG. 11 is a graphical representation of any displacement of the buoy with a horizontal component and a vertical component, and of the corrected pseudo-distance in the geodesic local coordinate system; FIG. 12 is a flowchart of a variant of the positioning method of FIG. 7 in the case of receiving bi-frequency radiolocation signals with an antenna having two phase centers; FIG. comparative view of a first time series of the vertical positrons of the buoy calculated from measurements of pseudoranges determined by a conventional method, and a second time series at the same times of the vertical positrons of the buoy calculated from measurements of pseudo -distances determined according to the method of the invention, and - Figure 14 is a comparative view of the statistics of the short-term accuracy of vertical position measurements of the buoy described in Figure 13 in each of the two time series. According to FIG. 1, a maritime buoy 2 forming a mobile comprises a floating platform 4, a first stage 6 housing an inertial unit 8 and a battery 9 for power supply, a data storage and retrieval unit 10, an emitter 11, a second stage 12 housing a GPS radiolocation receiver 14 and a hybrid processing and integration unit 16, a GPS reception antenna 18 and a protective dome 20. The flotation platform 4 comprises a flange 22 rigid hollow, shaped toric and filled with air, sandwiched and fixed between a circular lower floor 24 rigid and a circular rigid upper floor 26. The first stage 6 is a cylinder provided, at one end on a lower level 28 with fastening tabs not shown in the figure, and closed at the other end by an upper floor 30 on an upper level 32. The first stage 6 is fixed at the lower level 28 by fastening screws also not shown passing through the tabs, and sealingly at the periphery from the upper level 32 to the floating platform 4, by a seal 34 in the form of a skirt. The inertial unit 8 and the battery 10 are fixed inside the first stage 6 on the upper floor 26 of the floating platform 4 by their respective boxes by means of screws not shown. The inertial unit 8 comprises a reference point P origin of three gyroscopic axes xP, yP, ZP of reference, the point P being fixed with respect to the maritime buoy 2. The inertial unit 8 also comprises a local vertical accelerometer 35 capable of measure the vertical acceleration of the buoy along a local vertical terrestrial axis.

The second stage 12 is a cylinder of diameter smaller than that of the first stage 6 provided with fixing lugs at one end on a lower level 36 and closed by an upper floor 38 at the other end on an upper level 40.

The second stage 12 is fixed to the upper floor 30 of the first stage 6 by unrepresented fastening screws passing through the legs of the second stage 12. The GPS radiolocation receiver 14 and the hybrid processing and integration unit 16 are attached to the upper floor 30 of the first stage 6 by their respective housings by means of screws not shown in Figure 1. The radiocommunication transmitter 11 with an integrated transmitting antenna on its upper face is fixed on the upper floor 30 on the outside second floor 12.

The GPS reception antenna 18 is fixed on the upper floor 38 of the second stage 12. The receiving antenna 18 comprises a phase center, designated G, serving as a reference for the reception of GPS signals transmitted at the same carrier phase L1 by at least four satellites of the GPS system 42, 44, 46, 48, designated respectively S1, S2, S3, S4 through corresponding radio links 50, 52, 54, 56. The protective dome 20, made of synthetic material and with high radio-frequency permittivity, is fixed at a periphery to the upper floor 38 of the second stage 12 by screws and fixing lugs, a seal being deposited between the periphery of the dome 20 and the upper floor 38.

The vector B connecting the phase reference center G of the GPS antenna 18 to the reference point P of the inertial unit 8 is called the lever arm associated with the phase L1. According to FIG. 2, the set of markers used for the positioning or the location and / or the determination of the orientation or attitude of the buoy 2 comprises a quasi-inertial reference designated in English "Inertial frame" and designated by reference-mark. i, a terrestrial reference landmark called in English "Earth-centered Earth fixed frame" and designated by e-mark, a local geodesic landmark designated in English by "Local Level frame or Navigation frame" and designated by landmark-Il, a landmark of the buoy related to the rigid structure of the buoy 2 called "body frame" designated by b-mark, and a reference of the inertial unit related to the structure of the buoy called "instrumental frame" and designated by mark-p .

The reference-i comprises an origin 0 which is the center of mass O of the Earth at a reference moment tio, an axis x ', pointing to the true vernal equinox (ascending node between the celestial equator and the ecliptic) contained in the equatorial plane, an axis z 'coincides with the mean axis of rotation at the time t; o January 1, 2000 at 12 o'clock UT (Universal Time), an axis y' directly completing the inertial reference . The reference-e comprises the origin O center of mass of the Earth, an axis xe contained in the plane of the equator and passing by the point of intersection of the equator with the meridian of Greenwich, point by which in sense equatorial longitudes, an axis ze parallel to the mean terrestrial rotation axis of the reference ellipsoid defined in the World Geodetic System (WGS 84) 1984, a y axis complementing direct way the marker-e. The e-mark is the GPS positioning reference of the GPS constellation. The reference-Il used here is a marker that is a function of the position of the mobile at a predetermined time and is ideal for navigation by inertial unit. The geodetic local coordinate system is also called the navigation marker. The H-mark is linked to the mobile, here at the reference point P of the inertial unit, and moves with the buoy 2. The mark-II comprises an axis z "which is normal to the reference ellipsoid of the Earth, an axis x "directed towards the east direction geodesic and tangent to the local meridian, and a y axis" directed to the North complementing directly the reference-Il. The marker-It is useful not to provide the coordinates of the mobile but to provide the components according to the local directions that is to say the North, East and vertical, the buoy velocity vector and / or the orientation or attitude of the buoy The directions of the marker-II intervene in the determination of the matrix of rotation (CO of passage from the reference-H to the mark-e .The mark-b is a mark arbitrarily fixed to the buoy whose origin coincides with the origin of the geodesic local reference mark II, here the reference center P of the inertial unit.

Here, the mark of the buoy comprises a zb axis said high, an axis xb said before or prou and an axis yb said left or port complementing directly the mark-b buoy. The reference-p of the inertial unit associates the reference materialized by the sensitive axes of the gyroscopic sensors constituting an oriented trihedron. This mark is not necessarily orthogonal and the transition matrices between the p-mark and the -b mark must be determined beforehand by a suitable or dynamic geometric calibration protocol. The inertial unit 8 is disposed on the buoy so as to align gyroscopic reference axes xP, yP, zP on the axes xb yb zb of the mark b of the buoy 2. According to FIGS. 3, 4, 5, the orientation of the buoy 2, also called attitude, is defined by three Euler angles cp, 8, linking the reference-b with respect to the reference gyroscopic axes xP, yP, zP of the inertial unit 8 and to the reference-Il in the case where the p-mark of the inertial unit 8 is aligned with the mark -b of the buoy. The first angle of Euler designated by the letter cp, illustrated in Figure 3 and called "roll" in English, is the angle of roll of which the buoy 2 rotates around the axis xb.

The second angle of Euler designated by the letter 8, illustrated in Figure 4 and called in English "pitch", is the pitch angle which rotates the buoy 2 around the yb axis. The third angle of Euler designated by the letter ip, illustrated in Figure 5 and called in English "yaw or heading" is the angle of heading or yaw of which the buoy 2 around the zb axis. The attitude variations cp, 8, qi respectively correspond to angular velocities obi 'of rotation of the mark b of the buoy 2 which are detected by the gyrometers of the inertial unit 8. According to FIG. 6, a positioning device 100 comprises the receiving antenna 18 of the GPS signals, the GPS radiolocation receiver 14, a coaxial link 102 connecting the antenna 18 and the receiver 14, the inertial unit 8, the hybrid processing and integration unit 16 Positioning and attitude of the buoy 2, the data storage and retrieval unit 10, and the radiocommunication transmitter 11. The positioning device 100 comprises three separate electrical energy converters, not shown in FIG. 6 and connected to the battery 10, respectively supplying the radiolocation receiver 14, the inertial unit 8 and the hybrid processing and integration unit 16. between the phase G of the receiving antenna 18, associated with the frequency f1, constitutes the reference point of the reception instant t of a GPS signal transmitted by any visible transmitting satellite 42, 44, 46, 48, on a machine at frequency f1. The radiolocation receiver 14 comprises an input 104 connected to the receiving antenna 18 via the antenna-receiver link 102 and two outputs 106, 108 able respectively to supply data signals and measurement signals.

Here, the radiolocation receiver 14 is a mono-frequency receiver f1 of GPS signals emitted by the GPS transmitter satellites, here four in number S1, S2, S3, S4, each transmitting satellite 42, 44, 46, 48 having compared to the buoy an elevation greater than a predetermined threshold value, for example equal to 5 degrees.

The radiolocation receiver 14 comprises connected in series: - a radio frequency (RF) reception chain 110 intended to amplify, filter and convert the frequency of the GPS signal received at the antenna 18, - a conversion unit 112 comprising an analog / digital converter not shown digital (CAN) coupled to an Automatic Gain Control (AGC) chain, also not shown, - a signal processing unit 114 able to demodulate the digital signal from the conversion unit 112 into data and to make rough measurements of pseudo-distances and / or phases 1 (t) and / or velocities and / or angles.

The radiolocation receiver 14 also includes a clock 116 connected at a first input 118 to the reception channel 110 to provide a reference frequency to slave to the received GPS signal.

The clock 116 is also connected to a second input 120, respectively to a third input 122, to the conversion unit 112, respectively to the signal processing unit 114, to provide the units 112, 114 with marks. of time and associated dates.

The inertial unit 8 comprises a control input 130, able to receive calibration data and an initialization command at a reference position provided by an input member 131 represented by a dotted outline, an output 132 able to provide attitude angles, the coordinates in the b-mark of the buoy of the lever arm B formed by the vector connecting the reference point P of the inertial unit 8 to the center of phase G of the antenna 18, the displacement in translation of the buoy 2 according to the local vertical, designated by dth. The inertial unit 8 here is a SINS linked component plant (English denomination "Strap down INERTIAL SYSTEM") comprising three gyrometers 134, 136, 138, here optical laser (called fiber optic gyroscope) and arranged along three orthogonal axes, each capable of detecting a respective angular velocity along a predetermined gyroscopic axis. The components of the angular velocity wbl1 are respectively denoted w, wB, w ~ according to the normals n, nB, n ~ of the faces A, B, C of the housing of the inertial unit 8 aligned with the gyroscopic axes. The inertial unit comprises the vertical accelerometer 35 capable of measuring the acceleration of the buoy 2 along the local vertical, that is to say the axis z ° and to determine the vertical displacement in translation dth of the buoy. 2 by a double temporal integration of the acceleration.

The inertial unit 8 also comprises a calibration and initialization memory 140, a correction unit 142 of the angular velocities, an integration unit 144 of the angular velocities corrected up to a predetermined instant tk with respect to an initial reference instant. to Eulerian angles cp (tk), 6 (tk), 1P (tk), and a transfer unit 148 of inertial data such as, in particular, the coordinates of the lever arm B in the reference-b, the Eulerian angles. and vertical displacement in translation at times tk.

The calibration memory 140 comprises an input 150 connected to the input 130 of the inertial unit 8, a first output 152 connected to the correction unit 142, a second output 153 connected to the transfer unit 148 of the inertial data, and a third output 154 connected to the angular integration unit 144. The calibration memory 140 is able to record a predetermined matrix for passing from the reference-p to the reference-b designated CP and the coordinates of the lever arm Bb in the mark b buoy 2 provided by the input member 131.

The correction unit 142 comprises a first input 156, a second input 158 and a third input 160, each input 156, 158, 160 being respectively connected to a different gyro 134, 136, 138, and a fourth input 162 connected to the first output 152 of the calibration memory 140.

The correction unit 142 of the angular velocities measured by the gyrometers 134, 136, 138 is able, as a function of the correction matrix CP supplied by the calibration memory 140, to correct bias, scale, and error errors. orthogonality due to the intrinsic defects of the gyrometers 134, 136, 138 and due to misalignment of their axes relative to the mark-b of the buoy 2 or the initial mark-II. The correction unit 144 is able to provide an angular velocity of the reference-b around the reference-Il with components in the reference-b said corrected, designated by wbb, by multiplying the same vector wlb whose components are in the reference-p by the correction matrix CP.

The angular integration unit 144 comprises a first input 164 connected to the calibration and initialization memory 140, a second input 166 connected to the output of the correction unit 142 and an output 168 connected to the control unit. transfer 148 of the inertial data at a predetermined sampling time tk with respect to an initial reference time to, with tk equal to the sum of to and k times a sampling period designated by Tech. The integration unit 144 is able to initialize at the instant to, the Eulerian angular variables of output cp (to), 8 (to), qi (to) to zero when receiving a signal from initialization command received at the first input 164 and transmitted from the calibration memory 140. The angular integration unit 144 is able to integrate the corrected angular velocity o by time slot over the sampling time Tech. in measurements of Euler angles 9 (tk-1, tk), 6 (tk-1, tk), 1P (tk-1, tk) traveled between instants tket tk, the instant tk of rank k succeeding the previous sampling time tk-1 of rank k-1, with tk equal to the sum of tk-1 and Tech, and calculating at each successive instant tk the Euler angles according to the equations: tk) = 9 (tk-1, tk) + 9 (tk-1), e (tk) = e (tk-1, tk) + e (tk-1), and 1P (tk) = lP (tk-1) 1, tk) + IP (tk-1). The transfer unit 148 of the inertial data comprises a first input 174 connected to the output 168 of the angular integration unit 144, a second input 176 connected to the second output 153 of the calibration memory 140, a third input 177 connects the local vertical accelerometer 35 and an output 178 connected to the hybrid processing and integration unit 16. The transfer unit 148 of the inertial data is adapted to receive the coordinates of the lever arm Bb in the mark-b of the buoy 2, the displacement dth of the buoy 2 according to the local vertical, that is to say the axis z °, and the angles of Euler cp (tk), 6 (tk), 1P (tk) calculated at each successive instant tk. The transfer unit 148 of the inertial data is capable of supplying the hybrid processing and integration unit 16 with the coordinates of the lever arm Bb in the marker -b of the buoy 2, the displacement dth of the buoy 2 according to the local vertical, and the Euler angles cp (tk), 6 (tk), 1P (tk) calculated at each successive instant tk. The hybrid processing and integration unit 16 comprises a first input 180 and a second input 182 respectively connected to the first output 106 and the second output 108 of the radiolocation receiver 14. The hybrid processing and integration unit 16 also comprises a third input 184 connected to the output 132 of the inertial unit 8 and a fourth input 186 connected to the input member 131 adapted to receive the coordinates of the lever arm BG formed between the center of gravity CG of the buoy 2 and the point P of the inertial unit 8 in the mark -b of the buoy.

The hybrid processing and integration unit 16 comprises an output 187 for supplying the data storage and retrieval unit 10 with a time series of positioning coordinates of the buoy 2 in the geodesic landmark.

The hybrid integration processing unit 16 comprises an input memory 188 of raw data and measurements, a computer 190 and a working memory 192 associated with the computer. The input memory 188 is input connected to the three inputs 180, 182, 184 and output to the computer 190 by a bidirectional link 194.

The input memory 188 is able to receive the measurements and the conventional raw data of radiolocation provided by the radiolocation receiver 14 and to save them in a raw data file arranged and coded in a format called RINEX (denomination of "Receiver Independent Exchange Format ") to combine receiver observations from different manufacturers and use a single post-processing software. The input memory 188 is also able to receive the Eulerian angles at the instant tk, the displacement of the buoy according to the local vertical, the coordinates of the lever arm B in the mark -b of the buoy, where appropriate the coordinates of the lever arm BGb in the same b-index when it is non-zero, and to save these data in a raw data file formatted for example according to standard type RINEX. The input memory 188 is adapted to receive positioning data from the satellites Si, i ranging from 1 to n, where n is the maximum number of channels of the buoy's radio-locating receiver, broadcast periodically in the scene by the satellites themselves, demodulated and retransmitted by the radiolocation receiver of the buoy. The computer 190 is connected to the working memory 192 through a bidirectional link 196. The computer 190 is able to execute a set of instructions forming a computer program provided from a non-recording recording medium. FIG. 6. The computer 190 is able to determine, by a conventional global positioning method, the positioning of the phase center G of the buoy receiver 2 antenna from the conventional raw data of pseudoranges and / or or phase associated with each satellite and global positioning data Si satellites. The computer 190 is adapted to determine for each satellite Si, the elevation angle of the satellite Si seen from the center of phase G from the coordinates of overall positioning of the phase G center of the antenna determined by a conventional global positioning method and from the global positioning coordinates of the Si satellite. The computer 190 is capable of determining for each satellite the angle of the satellite seen from the phase G center of the antenna relative to the direction of the geographical north. The computer 190 is able to process the conventional raw data provided by the radiolocation receiver 14 by various processing tasks to transform each conventional raw data type pseudo-distance or phase into a new raw data called raw corrected without having combined between they are conventional raw data, in particular pseudo-distance or phase data measured and determined according to a conventional method. After correction of the conventional measured pseudo-distance or phase-like raw data, the computer is able to process by conventional algorithms ordinarily applied to the conventional raw data, the raw data corrected themselves in order to determine the positioning of the buoy 2 at each moment t. The radiocommunication transmitter 11 connected to the output 187 of the computer 190 is able to retransmit the calculated position of the buoy 2 for different times t of observations or to retransmit the raw data of the input memory 188 through the computer 190 for delayed treatment. As a variant, the computer only performs the transformation tasks of the conventional raw data into corrected raw data that will be broadcast to a remote processing center for determining the positioning of the buoy 2. In a variant, the gyrometers are mechanical gyroscopes to a degree of freedom adapted to detect an angular variation of the marker b connected to the buoy around a predetermined axis.

In a variant, the inertial unit comprises an input capable of receiving a local positional signal in stationarity ("motionless" in English) from the point P of the inertial unit 8 in the reference frame e, the signal being determined by a conventional method referred to in FIG. English "gyro-compassing". According to this conventional method, the initial values of the roll, pitch and yaw angles relative to the horizontal plane and the north direction are calculated at a time t0. The accuracy of the local position in stationarity of the point P is a few centimeters. The radiocommunication transmitter 11 connected to the data storage and retrieval unit 10 is able to send through a radio link in real time or in deferred time the data stored in the storage and retrieval unit. data 10. According to Figure 7, a method of positioning or dynamic location of the buoy 2 comprises a first sequence of steps 202, 204, 206 followed by two steps 208 and 210 executed in parallel, then a succession of steps 212 , 214. Steps 202 and 204 constitute so-called geometric calibration of the system. For these steps, a so-called dynamic calibration can be considered. In the step 202 called alignment step, an operator aligns the orientation of the sensitive axes of the gyroscopes xP, yP, zP of the reference-p of the inertial unit with respect to the reference -b related to the rigid structure of the buoy 2 and / or relative to the H-mark. The alignment is performed for example by a tonometric method using tacheometers and reflective targets deposited on the buoy 2 and the inertial unit 8 at selected locations.

This method can be supplemented by auxiliary GPS reception measurements made at well chosen locations. In the calibration step 204, the respective positions of the phase center G, the center of gravity GG of the buoy 2, the fixed reference point P of the inertial unit 8 are determined accurately by an optical method using tacheometers and or a method using a radiolocation calibration-base, in the b-coordinate system or in the II-coordinate system, which has also been precisely determined.

In the same calibrating calibration step 204, the inertial unit 8 can be calibrated by measurements of angular variations called dynamic calibration from axes and calibration angular velocities known precision of the buoy 2 mounted on a robotic arm in a laboratory.

From the measurements and calibration data, the correction matrix CP is determined for a b-mark aligned with the H-mark. The correction matrix CP, the coordinates of the lever arms Bb are loaded into the calibration memory 140. In the initial step 206 initialization and synchronization, at a time to initialization, an initialization control signal is output from the calibration memory 140 and then the integration unit 144 calculates the original Eulerian angular output variables cp (to), 8 (to), qi (to) to zero. This procedure refers to the procedure of leveling the inertial unit called "levellings". At time to, the b-mark linked to the tag 2 and the marker-Il are aligned.

In the same step 206 initialization and synchronization, at the instant to the clock 116 of the receiver 14 is synchronized with the Si GPS satellite clocks with different clock offsets according to each satellite Si. Each respective phase 1i (to) corresponding to the carrier at the frequency f1 of each satellite Si is measured by the receiver 14. The index i varies from 1 to n, n denoting the number of maximum GPS channels that the receiver 14 can process. In a next step 208, two steps 216 and 218 are executed successively. In step 216, at the measurement instant t, for each satellite Si, i varying from 1 to n, the phase 1i (t) and / or a propagation time 'ti (t) of a signal, emitted by the satellite Si, between the satellite Si and the center of phase G, is measured for a time of receipt at the buoy. PGPS (t, i) generically designates the conventional gross pseudo-distance, calculated from 1i (t) and / or zt (t), separating the satellite Si from the center of phase G.

For i varying from 1 to n, each phase 1i (t) expressed in number of cycles can be converted into a pseudo-spatial distance Li (t) defined by the equation: L i (t) = Â [4 i (t ) ù 4 i (to)] = PGPS (t, i) where A denotes the wavelength of the carrier at the frequency f1. For i varying from 1 to n, each propagation time r. (t) can be converted to a pseudo-distance designated by Pi (t) defined by the relation: Pi (t) = cr (t) = PGPS (t, i) where c denotes the speed of light in the vacuum. In known manner, the measurement of the propagation time r. (t) required for a signal transmitted by the satellite Si to reach the receiver is implemented by signals encoded on the carrier waves by modulating the phase thereof. So that the receiver can recognize the observed satellite If, each satellite Si transmits a code of its own. A replica of the code sequence is generated by the receiver together with the satellite. The shift r. that the replica must undergo in order to with the received code corresponds to the propagation time that put the signal to traverse the distance separating the satellite Si to the receiver at the moment of reception t. The time offset multiplied by the speed of light in the vacuum provides the pseudo-distance measurement Pi (t). The order of magnitude of the resolution of the pseudo-distance measurement Pi (t) is between ± 0.3 meters and ± 3 meters. In known manner, the measurement of the phase 1i (t) of the carrier wave at the frequency f1 consists of comparing the phase of the modulated carrier of the received GPS signal with the phase of a wave generated inside the receiver 14 by the clock unit 116 and theoretically, this phase difference oscillates between 0 and 2rr. Thus, the phase difference measurement 1i (t) ù 1i (to) can be interpreted as an accurate measurement of the variation of the receiver distance 14 (phase center G1) - satellite Si since the initial time to. The resolution of a phase measurement can reach a few millimeters. It is enough that one of the sizes r. (t), 1i (t), Li (t), Pi (t) is supplied to raw data input memory 188 as an observable to be able to determine the classical raw pseudo-distance pGPS (t, i). For example, the observable 1i (t) is supplied to the raw data input memory 188 as a number of cycles, the number having an integer part and a fractional part.

In particular, when the receiver 14 has acquired the phase of the GPS signal received for example with a Costas loop, the initial phase 1i (to) for each index value i is set to zero. In the same step 216, the receiver receives, at time t, the GPS coordinates of each satellite Si supplying the radiolocation signals of the buoy 2 corresponding to the instant t of reception. These coordinates are regularly broadcast by the satellites of the constellation. These coordinates for i fixed are for example the longitude designated by 2.GPS (t, i), the latitude designated by cIDGps (t, i) and the height designated by hGps (t, i).

In step 218, one of the magnitudes zti (t), 1i (t), Li (t), Pi (t) is supplied to raw data input memory 188 as an observer to determine the pseudo-distance pGPS (t, i) respective conventional gross associated with a separate satellite Si. In the same step 218, the global positioning coordinates of each satellite Si supplying the radiolocation signals of the buoy 2 and corresponding to an instant sufficiently close to or equal to the instant t are given to the input memory 188 of raw data. In step 210, executed in parallel with step 208, the inertial unit 8 determines the coordinates of the lever arm B ° in the reference-Il.

Step 210 comprises a sequence of steps 220, 222, 224 and 226. In step 220, the correction unit transforms the corll vector, angular variations provided by the gyrometers in the b-frame into the multiplying by the rotation matrix CP resulting from the geometric calibration In step 222, the angular integration unit 144 integrates the corrected angular velocity vectors emitted by the correction unit between the initial moment to and the sampling time tk internal to the integration unit 144 corresponding most closely to the instant t of reception and observation of the GPS signals by the receiver 14. The angular integration unit then determines the Eulerian angles corresponding cp (t), 8 (t), yi (t).

In the same step 222, the vertical accelerometer 35 determines the vertical displacement in translation of the buoy 2 designated by dth (t) by a double temporal integration of the measured acceleration. Like the gyroscopes, a calibration step has been carried out beforehand. In the same step 222, the vertical accelerometer 35 determines the vertical displacement displacement of the buoy 2, denoted by dth (t), by a double temporal integration of the measured acceleration. In the same step 222, a synchronization procedure is started using the clock of the receiver 14 and a dating clock of the observations provided by the gyrometers and the accelerometer 35. In step 224, the transfer unit 148 of inertial data receives the coordinates of the lever arm Bb emitted from the calibration and initialization memory 140, the Eulerian angles cp (t), 8 (t), p (t) provided by the unit of angular integration 144 and the vertical displacement in translation of the buoy 2, dth (t) provided by the local vertical accelerometer 35. Then, in step 226, the inertial data transfer unit 148 supplies the input memory 188 with the coordinates of the lever arm Bb designated by bX, by, bZ in the buoy mark-b, the values Eulerian angles cp, 8, considered at time t, and the vertical displacement in translation of the buoy 2 dth (t), denominated in English "heave". In the same step 226, the input memory 188 receives the coordinates of the lever arm BGb from the input member 131. As a variant, the provision of the coordinates of the lever arm BGb to the input memory 188 is performed only once at the same time as the initialization step 206. In the step 212, for each satellite Si of index i, a corrected pseudo-gross distance po, (t, i) is calculated as a function of the pseudo-classical distance pGPS (t, i) associated with the same satellite Si, Eulerian gyroscopic angles considered at the same instant t and designated respectively by cp, 8, ip, of the vertical displacement displacement of buoy 2, dth ( t), global positioning coordinates of each satellite Si.

Step 212 comprises a succession of steps 230, 232, 234, 236. In step 230, in a known manner, the computer determines the overall position of the phase center G of the antenna in the global positioning system, here GPS from the classical pseudo-distances pGps (t, i) associated with the satellites Si, i varying from 1 to n. In known manner, for each satellite Si, the computer determines the elevation angle of the satellite Si seen by the phase center G of the antenna and designated by E (t, i) from the global positioning coordinates of the phase G center of the antenna 18 determined by a conventional global positioning method and from the global positioning coordinates of the satellite Si. In a manner also known, the computer determines for each satellite Si the angle of the satellite seen by the phase G center of the antenna with respect to the direction of the geographic North and designated by Az (t, i). In step 232, the calculator first calculates a vertical displacement of the buoy observed at time t and denoted by dh (t) as a function of the coordinates of lever arm B, bx, by, bz, Eulerian angles cp, 8, qi observed at time t, and of the vertical displacement in translation dth (t) according to the equation: dh (t) = 8 (ùbx cos 8 ùby sin çosin 8 ùbz cos çosin 8) + ço (bycos çocos 8 Then, in the same step 232, the calculator determines the vertical corrected pseudo-resistance po, (t, i) associated with the satellite Si as a function of the vertical displacement of the buoy calculated and observed at the instant t, dh (t), of the classical pseudo-distance pGPS (t, i) determined in a conventional manner Si in a global positioning system between the center of phase G and the satellite Si, and of the angle d elevation El (t, i) of the satellite Si seen by the center of phase G according to the expression: p, 27 (t, i) = p, 2PS (t, i) + dh2 (t) + 2 sgn (dh (t)) pGps (t, i) dh (t) sin (EL (t, i)) in which sgn (.) designates the sign function.

The geometric representation of the above expression is described in FIG. 8 as the relation existing between the sides of the triangle (H +, G, Si) or the triangle (H-, G, Si), the choice of the triangle depending on the sign of vertical displacement dh (t). The detailed expression of the corrected vertical pseudo-distance associated with the satellite Si is written: P o (t Z) 1/2 P ~ PS (t, i) + (0 (ùb1 cos0ub1 sincpsin0ub1 coscpsin0) + çp (blycoscpcos0ub1 sincpcos0 ) + dth) 2 + 2sgn (h) pGPS (t, i) sin (EL (t, i)) (0 (ùb1 cos0ub1 sincpsin0ub1 coscpsin0) + çp (bl, cos cos ùb1 sincpcos0) + dth) In step 234, the calculator first calculates a horizontal displacement of the buoy observed at time t and designated by dl (t) function of the coordinates of the lever arm B, bx, by, bz, Eulerian angles cp, 8, qi next the equation: dl = [(b1 (ùcos9sinty + cos9costy) + b1 (ù cos q sin ty + sin q sin 9 cos ty ù cos cos ty + sin q sin 9 sin ty) + b1z (sin cos cos y cos Then, in the same step 234, the calculator determines the angle, designated by (1) (t, i), and formed between the direction of the horizontal projection of the center line of phase G-satellite Si and the direction of displacement t buoy 2, as a function of the horizontal displacement dl (t), the yaw angle ip, the x component of the lever arm, and the angle of the satellite Az (t (i) seen by the phase G center of the antenna with respect to the direction of the geographic north, as follows: c (t, i) = arccos (dl (t) / 2bx) ù yr ù Az (t) i) Next, in the same step 234, the calculator determines the horizontal corrected pseudorange pci0 (t, i) associated with the satellite Si as a function of the horizontal displacement of the buoy 2 calculated and observed at time t, dl ( t), the conventional pseudo-distance pGPS (t, i) conventionally determined in a global positioning system between the phase center G and the satellite, of the elevation angle E1 (t, i) of the satellite Si seen by the center of phase G and of the angle (D (t, i), according to the expression: p, 102Y (t, i) = ['1 (t, i) cos2El (t, i ) + dl2 (t) ù2pGps (t, i) dl (t) cos (EL (t, i) cos 1 (t, i)] / cos2El (t, i) 26 The geometrical representation of e the expression the horizontal corrected pseudo-distance p, (t, i) is described in FIG. 9 as the relations existing between the sides of the triangles (A, Si, C) and (A, Si, B). The geometric representation of the expression (1) (t, i) is described in FIG. 10 as the relations existing between the sides of the triangles (A, B, D) and (A, B, C). The detailed expression of the pseudo-horizontal distance pci01. (t, i) corrected associated with the satellite Si is written:

p2PS (t, i) cos2 El (t, i) + [blx (ùcos 9 sin + cos 9 cos v) + bly (ùcos sin + sin sin 9 cos ù cos vcos + sin sin 9 sin v) + b1Z (sin vcos ù cos sin 9 sin Plorr (t, i) = + sin sin ù cos sin cos v) 12 v2 ù 2pGPS (t, i) cos (EL (t, i) cos t (t, i) t // [ (w cos sin cos sin cos cos cos) cos v) + b1 (ù cos sin + sin 9 cos ù cos cos + sin sin sin sin v) + b1 (sin cos ù cos sin sin sin + sin sin ù cos sin 9 cos ~ r) I In step 236, the calculator determines the pseudo-general corrected distance designated by p ÔYY (t, i), associated with the satellite Si, the vertical displacement and the horizontal displacement respectively determined in step 232 and at step 234. The general pseudo-distance p 0YY (t, i) associated with the satellite is determined as a function of the conventional pseudo-distance pGPS (t, i), the pseudo-distance vertically corrected p ôYY (t, i), the horizontally corrected pseudo-distance pcio, (t, i), each associated with the same satellite, according to the expression: Pc0 (t, i ) = PGPS (t, i) + (Pion. (T, i) ûPGPS (t, i)) + (PyYY (t, i) ûPGPS (t, i)) Alternatively, the pseudo-general distance pc0 (t i) is an average of the pseudo-vertically corrected distance p ôYY (t, i) and the horizontally corrected pseudo-distance pci0 (t, i), the mean being selected from the set consisting of the algebraic mean, the mean barycentric, the geometric mean. In stage 214, the positioning of the buoy 2 is determined by a conventional method from the corrected pseudo-distances pc0 (t, i) according to the invention, for i variant. from 1 to n as new raw data, each corresponding to a different satellite Si.

The methods used in step 214 return to use the principle of spatial trilateration in which a measure of the unknown position of a point, here the point P or equivalently the point G in a three-dimensional space is made from the distance measurement on three transmitting points, here three different satellites S1, S2, S3 whose coordinates known by a precision orbitography have been corrected by deterministic correction coordinates corresponding to the attitude displacement of the buoy 2. The position sought here of the point P is therefore at the intersection of three spheres, each of the three spheres being centered at the known position of the satellite (calculated with the ephemeris) at the moment t of the corrected distance measurement of the attitude data. buoy 2, the radius of the spheres corre- sponding to the corrected pseudo-distances pc0 (t, i). Known methods of statistical or deterministic filtering may be used to a posteriori decrease the various effects of error sources contributing to the amplitude of the error residue.

Sources of errors include clock errors, orbits, and ionospheric and tropospheric refractions. It should be noted that if more than four satellites are observed, the accuracy and reliability of the positioning of the buoy 2 are higher. It should be noted here that single-frequency GPS receivers placed in the vicinity of the Earth's surface can use ionography scattered in the satellite reference message in the form of coefficients of a coarse model of the ionosphere adjusted by CET (Total Electronic Content). According to FIG. 12, a variant 300 of the method of FIG. 7 is implemented by a positioning device similar to that described in FIG. 6 but comprising a dual-frequency radiolocation receiver 14, that is to say capable of receiving GPS signals having a first carrier at a frequency f1 and a second carrier at a frequency f2. In this case, the GPS reception antenna 18 comprises a first phase center G1 associated with the frequency f1 and a second phase center G2, distinct from G1 and associated with the frequency f2. In known manner, an equivalent phase center, designated Geq, is defined by reducing the G1 and G2 phase centers to a single phase center. When the orientation of the GPS antenna of the radiolocation receiver 18 with respect to a satellite considered as Si is known, maps provided by the international GNSS service referenced with respect to the geographical north conventionally allow to correct the Equivalent phase center position Geq. The position of the equivalent phase center Geq is thus a function for a given satellite Si of the associated elevation E1 (t, i) and of the associated Az (t, i).

Like the method of Figure 7, the identical steps of the positioning method 300 of the buoy 2 are designated by the same reference numerals. The method of positioning 300 of the buoy comprises a first succession of steps 202, 304, 206 followed by two steps 208 and 310 executed in parallel, then a test step 311 with two outputs. Depending on the output of the test step 311, a step 312 or 313 is carried out, each being followed by the step 214. The step 304 is the step 204 in which the phase center G describes FIG. 1 is the equivalent phase center Geq obtained by reduction of the G1 and G2 phase centers. Step 310 includes the same steps 220, 224, 226 as step 210, except for step 322 that replaces step 222. In step 322, the same tasks as the step are executed. 222. In step 322, the inertial unit 18 is able, from the measurement data provided by the accelerometer 35 and / or the integration unit 144 to estimate a parameter of reliability of the inertial information, according to of time and designated by fiab (t), with a view to the decision of future use of the inertial data in the algorithm of correction of the conventional raw data pGPS (t, i) of pseudo-distance, or with a view to their non use and implementation of a statistical adjustment algorithm. The reliability parameter will translate a lack of reliability of the inertial data when the information of the Eulerian angles cp, 8, and / or of displacement in translation dth are non-existent, which corresponds to a "hole", or else erroneous by the setting evidence of drifts or offsets of excessive instruments. Steps 216 and 218 are executed identically to those of method 100.

Step 311 is a step of testing and switching on one of steps 312 or 313 depending on the binary state of the reliability parameter When a first state of the reliability parameter reflects a lack of reliability of the inertial information from the inertial unit 8, then the steps of correction of the pseudo-range raw data pGPS (t, i) for each of the satellites Si as a function of the inertial information are not executed and only the pseudo-distances pGPS (t, i ) determined by the conventional radiolocation methods are implemented in step 313. In the same step 313, a statistical adjustment algorithm on a predetermined model is applied to the conventional raw data pGPS (t, i) pseudo distances not corrected by current inertial information. In the same step 313, a prediction of the inertial information is carried out and a reset of the initial conditions of the integration units of the inertial unit is implemented for the Eulerian angles and the displacement-ment in translation.

When a second state of the reliability parameter indicates the presence of reliability of the inertial information, then the correction step 312 of the pseudo-distance raw data is implemented. Like step 212, step 312 includes steps 230, 232, 234, 236.

Step 312 comprises a step 330 interposed between steps 230 and 232 in which the position of the equivalent phase center Geq is corrected according to the knowledge for each satellite Si of the associated elevation E1 (t, i) and del ' associated Az (t, i) and maps provided by the International GNSS Center. This correction makes it possible to obtain for each satellite Si a new distinct lever arm B (Si) corresponding and to provide new coordinates of lever arm B (Si) for the implementation of the following steps 232, 234. The advantage to choose one of the two steps 312 and 313 is to take advantage of the improved positioning accuracy of the buoy provided by the method of the invention only at times when said method is effective. The advantage of measurements with a code carried by two carrier waves at frequencies f1 and f2 is that the corresponding pseudo-distances and phase observations can be finely corrected to remove the effect of the ionospheric delay. According to Figure 13, a first time series of the buoy's vertical positrons, calculated from measurements of gross pseudo-distances, which are determined by a conventional method, is represented by a curve in black line, the density of the curve. following the direction of the abscissae being such that it appears in the form of a band filled with black. According to FIG. 13, a second time series at the same times of the vertical positions of the buoy, calculated from pseudo-distance measurements corrected according to the method of the invention described in FIG. 7, is represented by a gray curve whose the variations are included in those of the curve representing the first series. It appears that the standard deviation of the fluctuations of the curve representing the vertical positioning of the buoy determined in a conventional manner, that is to say in black, is much greater than the standard deviation of the gray curve representing the positioning of the buoy determined according to the method of the invention of Figure 7. Thus, it appears that the accuracy of the positioning of the buoy 2 is improved when the method of the invention is implemented.

The accuracy is further improved when the method, described in Figure 12, is implemented. According to Figure 14, the accuracies are translated through the standard deviations of the fluctuations of the curves compared to the average of the measurements over a short period of observation, precisely on slippery windows of 120 seconds. According to Figure 14, the accuracy statistics for vertical buoy position measurements described by the curves in Figure 13 reflect the reliability and stability of the measurements over a short observation period. The ratio of the standard deviation of the black curve of the first series of measurements to the standard deviation of the gray curve of the second series of measurements indicates a reduction of the measurement noise by a factor of 10. In Alternatively, the increase in observations can be made by measurements of ground reference stations retransmitted to the radiolocation receiver 14 of the buoy. As a variant, a geometrical effect called the English "windup phase" is corrected from the knowledge of the relative position of the antenna of the receiver relative to the geographic North, ie the angle of rotation dz. Z axis in the mark -b of the buoy. According to the so-called "windup phase" effect, when the antenna of the receiver rotates relative to the satellite transmitter antenna Si by a predetermined angle, the phase angle measured as the difference between the angle of the instantaneous field, polarized circularly to the right and received by the antenna 18 of the receiver, and a predetermined reference direction on the antenna 18 of the receiver varies depending on the h of the antenna 18 of the receiver. Therefore, from the knowledge of the angle of h of the antenna of the receiver with respect to a satellite Si considered, the associated pseudo-distance Li (t) corresponding to 1i (t) can be corrected additionally. to become a pseudo-distance corrected more precisely.

Claims (15)

REVENDICATIONS1. A method of dynamically locating a mobile (2) having a rigid structure by a hybrid locating device (100) comprising: a radiolocation receiver (14) connected to a receiving antenna (18) having a center of phase (G) ) associated with a frequency f1, the receiving antenna (18) being fixed relative to the structure of the mobile (2), and a triaxial inertial unit (8) having a reference point (P) center of a reference mark of reference (p) of the inertial unit (8), the center (P) being fixed relative to an orthonormal frame (b) of the structure of the mobile (2), comprising the steps of receiving by the radiolocation receiver (14) ) and with respect to the phase center (G) of the receiving antenna (18), at a predetermined observation time t a plurality of radiolocation signals each transmitted at the frequency f1 by a transmitter of a satellite (50). , 52, 54, 56) different, visible from the mobile (2), treat the Received signals and conventionally determining (208) conventional raw pseudo-range information pGPS (t, i) observed at time t, providing (208) by the radiolocation receiver to a data memory raw (188) the classical raw pseudo-range information pGPS (t, i) observed at time t, providing (226) by the inertial unit (8) to the raw data memory (188) at time t for observing current inertial information associated with the instant t of the mobile (2) with respect to a local geodetic reference mark, characterized in that it comprises the steps of: first, for each fixed satellite (Si), determining (230) the elevation angle (EI (t, i)) under which the satellite (Si) is viewed from the phase center (G) of the receiver antenna as a function of the global positioning coordinates of the satellite (Si ) and the overall position of the phase center (G), the overall position of the phase center (G) being terminated according to the conventional pseudo-gross distances pGPS (t, i) associated with the satellites (50, 52, 54, 56), correcting (236) each pseudo-raw distance pGPS (t, i) to a corrected pseudorange pc0 (t , i) corresponding function of the raw pseudo-distance PGPS (t, i), current inertial information, elevation angle (El (t, i)), then determine (214) the geodesic local positioning of the in the geodesic local coordinate system It follows a conventional method of multilateration from the corrected pseudo-distances pc0 (t, i) as new raw data, each of the corrected pseudo-distances corresponding to a different satellite (Si). 2. A method of dynamically locating a mobile (2) according to claim 1, characterized in that the inertial unit (8) is able to determine from three gyrometers (134, 136, 138) angles Eulerian cp , 8, ip, respectively called roll, tan-gage and yaw, of transformation of the directions of the reference-b linked to the mobile (2) in directions of the local geodetic marker-II and to be determined from an accelerometer of local vertical (35) a displacement dth (t) in translation of the mobile (2) according to the vertical of the geodesic local coordinate system, and in that the inertial information comprises the transformation angles cp, 8, qi at time t, the displacement dth (t) in translation of the mobile (2) according to the local vertical and the coordinates bX, by, bZ of a lever arm vector (Bb) in the reference-b of the mobile (2), the arm vector lever (Bb) being defined as the vector connecting the reference point (P) of the inertial unit (8) at the phase center (G) of the receiving antenna (14), 3. Dynamic location method according to claim 2, characterized in that the corrected pseudo-distance satisfies the equation: p 0, (t, i) = pG2PS (t, i) + dh2 (t) + 2 sgn (dh (t)) pGps (t, i) dh (t) sin (EL (t, i)) in which sgn (.) denotes the sign function and dh (t) satisfies the equation dh (t) = 8 (bx) cos 8 û b, sin sin 8 û bz cos çosin 8) + ço (by cos çocos 8 ûbz sin çocos 8) + dth (t) 4. Dynamic location method according to claim 1, characterized in that it comprises the steps of determining for each satellite (Si) the angle of (Az (t, i)) of the satellite as seen by the phase center (G) of the receiving antenna (18) relative to the direction of the geographic North, for each satellite (Si), correcting the associated conventional pseudo-gross distance (pGPS (t, i)) to a corrected pseudo-distance (p ,,, (t, i)) corresponding function of the classical raw pseudo-distance (pGps (t, i)), current inertial information, elevation angle (El (t, i) ) and the angle of (Az (t, i)) of the satellite (Si) seen by the phase center (G) of the antenna (18) relative to the direction of the geographic north, the inertial unit ( 8) being able to determine from three gyrometers transformation angles cp, 8, p of the directions of the reference-b linked to the mobile (2) in directions of the local geodetic reference-Il, and the iner information current trends comprising the transformation angles cp, 8, .p at time t, the coordinates of a lever arm vector (Bb) in the reference-b of the mobile (2), bX, by, bZ, the lever arm vector (Bb) being defined as the vector connecting the reference point (P) of the inertial unit (8) to the phase center (G) of the receiving antenna (14), 5. Dynamic locating method according to claim 4, characterized in that the corrected pseudo-distance satisfies the equation: p oa (t, i) = [pG2Ps (t, i) cos2 El (t, i) + d12 ( t) ù 2pGPS (t, i) dl (t) cos (EL (t, i) cos "t, i)] / cos2 El (t, i) where d1 denotes a displacement satisfying the equation dl (t) = [(b, (ùcos 9 sin tv + cos 9 cos tv) + by (ùcos v sin tv + sin v sin O cos tv ù cos v cos tv + sin v sin O sin tv) + bz (singcostyucos ~ psinGsinty + sin ~ psintyùcos ~ psinGcostv)] ty And c (t, i) designates an angle satisfying the equation: c (t, i) = arccos (dl (t) / 2bx) ùtvùAz (t, i) 6. Dynamic locating method according to claims 2 and 4, characterized in that it comprises the steps of; in a step (232), first determine a vertical displacement dh (t) of the mobile (2) observed at time t as a function of the coordinates of the lever arm B, bx, by, bz, Eulerian angles cp, 8 , 4), and of the vertical displacement in translation dth (t) according to the equation: dh (t) = 8 (ùbx cos 8 ù by sin sin 8 ùbz cos sin 8) + ç (by cos çocos 8 ùbz sin çocos 8) + dth (t) and determine the pseudo-distance corrected vertical po, (t, i) associated with the satellite (Si) as a function of the vertical displacement (dh (t)) of the mobile (2) determined and observed at the moment t, the pseudo-classical distance pGPS (t, i), and the elevation angle El (t, i) of the satellite (Si) seen by the phase center (G) according to the expression p oYY ( t, i) = pG2PS (t, i) + dh2 (t) + 2 sgn (dh (t)) pGPS (t, i) dh (t) sin (EL (t, i)) in which sgn (.) denotes the sign function; in a step (234), the calculator first calculates a horizontal displacement dl (t) of the moving part (2) observed at time t, depending on the coordinates of the lever arm B, bX, by, bZ, Eulerian angles cp, 8, according to the equation: dl = [(box (cos cos sin sin + cos cos cos) + b1 (cos cos sin sin / sin sin cos cos VI cos cos VI + sin q sin G sin Then, in the same step (234), determine the angle t (t, t, i). ) formed between the direction of the horizontal projection of the line of sight of the phase center (G) -satellite (Si) and the direction of the horizontal displacement dl (t) of the mobile (2), as a function of the horizontal displacement dl (t) , the yaw angle ip, the component bX of the lever arm Bb, and the angle of the satellite Az (t, i) seen by the phase center (G) of the antenna (18) by relation to the direction of the geographic North, according to the expression c (t, i) = arccos (dl (t) 12bx) û ty ù Az (t, i) then, da in the same step (234), determine the pseudo-horizontal corrected distance pci0 (t, i) associated with the satellite (Si) as a function of the horizontal displacement dl (t) of the mobile (2) determined at time t, of the classical pseudo-distance pGPS (t, i) conventionally determined in a global positioning system between the phase center (G) and the satellite, of the elevation angle E1 (t, i) of the satellite ( If) seen by the phase center (G) and the angle t (t, i), according to the expression p, 102, (t, i) = [pG2PS (t, i) cos2 El (t, i ) + dl2 (t) 2pGps (t, i) dl (t) cos (EL (t, i) cos 1 (t, i)] / cos 2 El (t, i) in a step (236), determining a general pseudo-distance p 0, (t, i) corrected according to the vertically corrected pseudo-distance po, (t, i) and the pseudo-distance corrected horizontally pci01. (t, i), each associated with the same satellite (Si). 7. A method of dynamically locating a mobile (2) according to claim 6, characterized in that the pseudo-general distance pc0 (t, i) corrected is a function of the pseudo-classical distance pGPS (t, i) , the vertically corrected pseudo-distance p ôYY (t, i), and the pseudo-distance corrected horizontally pci0 (t, i), each associated with the same satellite Si according to the expression:. pc0 (t, i) = PGPS (t, i) + (pIOYY (t, i) ûPGPS (t, i)) + (p0YY (t, i) ûPGPS (t, i)) 8. A method of dynamically locating a mobile (2) according to claim 6, characterized in that the pseudo-general distance pc0 (t, i) corrected is an average of the pseudo-distance vertically corrected p ôYY (t, i ) and the pseudo-distance corrected horizontally pci0 (t, i), the average being selected from the set consisting of the average algebraic, the mean barycentric, the geometric mean. 9. A method of dynamically locating a mobile (2) according to any one of claims 1 to 8, characterized in that: the radiolocation receiver (14), connected to a receiving antenna (18) is bi -frequency adapted to receive signals at a first frequency f1 and a second frequency f2 and comprises two phase centers (G1) and (G2) respectively associated with the first frequency f1 and the second frequency f2; and in that the phase center (G) is the equivalent phase center (Geq) obtained by reducing the phase centers (G1) and (G2). 10. A method of dynamically locating a mobile (2) according to claim 9, characterized in that it comprises the step of: for each satellite (Si), determine the angle of (Az (t, i )) of the satellite (Si) seen by the receiving antenna (18) relative to the direction of the geographic North, correcting the equivalent phase center (Geq) a new equivalent phase center Geq (Si) depending on the angle of elevation (EI (t, i)) under which the satellite (Si) is seen from the receiving antenna (18), the angle of (Az (t, i)) of the satellite (Si) seen by the receiving antenna (18) with respect to the direction of the geographic north, determining the coordinates of a new lever arm B (Si) for use in calculating the corrected pseudo-distance pc0 (t, i) associated with the satellite (Si). 11. Dynamic location method according to any one of claims 1 to 10, characterized in that it comprises a decision step (311) of the subsequent use or not of the current inertial data, acquired in step (208), in the step of correcting the pseudo-range pseudo-distance raw data pGPS (t, i) as a function of the logical state of a reliability parameter (fiab (t)) of the inertial information, a function of time . 12. Dynamic location method according to any one of claims 1 to 11, characterized in that it comprises the steps of determining the angle of (Az (t, i)) of the satellite (Si) seen by the receiving antenna (18) with respect to the direction of the geographic north, and correcting the geometric effect known as the English "windup phase" from the knowledge of the relative position of the receiving antenna (18) with respect to the Geographical North or the angle of (Az (t, i)). 13. Instruction recording medium, characterized in that it comprises instructions for the execution of a method according to any one of claims 1 to 12, when these instructions are executed by an electronic calculator . 14. Device for locating a mobile (2) comprising: a radiolocation receiver (14), a reception antenna (18) connected to the radiolocation receiver (14), and having a phase center (G) associated with a frequency f1, the receiving antenna (18) being fixed relative to the structure of the mobile (2), a triaxial inertial unit (8) having a reference point (P) center of a reference mark (p) of the inertial unit (8), the center (P) being fixed with respect to an orthonormal reference (b) of the structure of the mobile (2), and a raw data memory (188), the receiver (14) being adapted to receiving, with respect to the phase center (G) of the receiving antenna (18), at a predetermined observation time t a plurality of radiolocation signals each transmitted at the frequency f1 by a transmitter of a satellite ( 50, 52, 54, 56), visible from the mobile (2), to process the received signals, to determine conventional raw pseudo-range information pGPS (t, i) observed at time t, and providing (208) to a raw data memory (188) the conventional raw pseudorange information pGPS (t , i) observed at time t, the inertial unit (8) being able to supply to the raw data memory (188) at the observation instant t current inertial information associated with the instant t of the mobile (2) with respect to a local geodetic reference mark, characterized in that it comprises a calculator suitable for: first, for each fixed satellite (Si), determining the elevation angle (EI (t, i)) under which the satellite (Si) is viewed from the phase center (G) of the receiver antenna according to the global positioning coordinates of the satellite (Si) and the overall position of the phase center (G), the overall position the phase center (G) being determined according to the associated conventional pseudo-gross distances (pGPS (t, i)) to the satellites (50, 52, 54, 56), correcting each pseudo-raw distance (pGPS (t, i)) to a corrected pseudo-distance pc01. (t, i) corresponding function of the raw pseudo-distance (pGPS (t, i)), current inertial information, elevation angle (EI (t, i)), and then determine local positioning geodesic of the mobile in the local geodesic locator-II according to a conventional multi-latency method from the corrected pseudo-distances pc0 (t, i) as new raw data, each of the corrected pseudo-distances corresponding to a satellite (Si ) different. Mobile, in particular an automobile, an airplane, a ship, a marine buoy, characterized in that it comprises a positioning device (100) defined according to claim 14.