WO2011039457A1 - Method and device for dynamically locating a moving body - Google Patents

Abstract

The invention relates to a method for dynamically locating a moving body having a rigid structure, implemented by a hybrid locating device including a radiolocation receiver connected to a receiving antenna having a phase centre (G) and a triaxial inertial measurement unit having a central reference point (P). The method includes a step (236) of correcting each raw pseudorange p _GPS (t, i), conventionally predetermined and associated with a separate satellite (Si), to form a corresponding corrected pseudorange p _corr (t, i) on the basis of the raw pseudorange p _GPS (t, i), the current inertial information, and the angle of elevation (EI(t,i)) under which the satellite (Si) is viewed from the phase centre (G).

Description

 Method and device for dynamically locating a mobile

 The invention relates to a method for measuring the dynamic positioning of a mobile, in particular an automobile, a plane, a ship or a maritime buoy, implemented using a simple hybrid device that combines a mobile device. receiver, provided with an antenna for receiving radiolocalization beacon signals, 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 information.

 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 receiving antenna having a phase center (G) associated with a frequency f1, 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 t a plurality of radiolocation signals each transmitted at the frequency f1 by a transmitter of a different, visible satellite from the mobile,

process the received signals and conventionally determine conventional raw information of pseudo-distances p _GPS (t, i) observed at time t,

providing by the radiolocation receiver to a raw data memory the conventional raw information of pseudo-distances p _GPS (t, i) observed at time t,

 providing the inertial unit with the raw data memory at the instant t of observation of the current inertial information associated with the instant t of the mobile with respect to a local geodetic reference,

 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 viewed from the phase center (G) of the receiver antenna as a function of the global positioning coordinates of the satellite (Si) and the global position of the phase center (G), the global position of the phase center (G) being determined according to the conventional pseudo-gross distances p _GPS (t, i) associated with the satellites,

correct each pseudo-gross distance p _GPS (t, i) to a corrected pseudo-distance p _corr (t, i) corresponding to the pseudo-gross distance p _GPS (t, i), current inertial information, of the elevation angle (El (t, i)),

then, to determine the geodesic local positioning of the mobile in the local geodesic locator-ll following a conventional multi-latency procedure from the corrected pseudo-distances p _corr (t, i) as new raw data, each of the pseudo-distances corrected for a different satellite (Si).

 According to particular embodiments, the method comprises one or more of the following characteristics:

 the inertial unit is capable of determining, from three gyrometers, the Eulerian angles φ, θ, ψ, respectively called roll, pitch and yaw, of transformation of the directions of the marker-b linked to the mobile in directions of the local geodetic reference-11. and determining from a local vertical accelerometer a displacement dth (t) in translation of the mobile according to the vertical of the local geodesic landmark, and

the inertial information comprises the angles of transformation φ, Θ, ψ at the instant t, the displacement dth (t) in translation of the mobile according to the local vertical and the coordinates b _x , b _y , b _z of an arm vector lever (B ^b ) in the reference-b of the mobile, the leverage vector (B ^b ) being defined as the vector connecting the reference point (P) of the inertial unit to the center of phase (G) of the receiving antenna,

 the corrected pseudo-distance satisfies the equation:

Pcorr (t, i) = pies (, 0 + dh ² (t) + 2 sgn (dh (t)) p _GPS (t, i) dh (t) sin (EL (i, * ^' ))

where sgn (.) designates the sign function and dh (t) satisfies the equation dh (t) = 6-b _x cos 0 - b _y sin φύ Θ- b _z cos φήη Θ) + ç (b _y cos < pcos 0 -b _z sin <pcos Θ) + dth (t) the process 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 (1 8) relative to the direction of the geographic North,

 for each satellite (Si), correct the conventional gross pseudo-distance

(p _GPS (t, i)) associated with a corrected pseudo-distance (? _COT (t,) corresponding to the function of the classical pseudo-distance (p _GPS (t, i)), current inertial information, the angle of elevation (El (t, i)) and the angle of (Az (t, i)) of the satellite (Si) seen by the phase center (G) of the antenna with respect to the direction of the geographic North,

 the inertial unit being able to determine from three gyrometers the angles of transformation φ, θ, ψ of the directions of the marker-b linked to the mobile in directions of the local geodetic reference-ll, and

the current inertial information including the transformation angles φ, θ, ψ at time t, the coordinates of a lever arm vector (B ^b ) in the reference-b of the mobile, b _x , b _y , b _z , the lever arm vector (B ^b ) 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 ^{ _rr ( ^{ _> = \ -PI _PS ( ^{ _> ^{cos2 E} t, 0 + dl ² (t) - 2p _GPS (t, i) dl (t) cos (EL (t, i) cos Φ (ί, i )] / cos ² El (t,

In which d1 denotes a displacement satisfying the equation

 dl (t) = [(^ (-cos tf sin ^ + cos <9cos ^)

+ b _y (-cos if ψ + sin if #cos ψ - cos ç cos ψ + sin if #sin ψ)

+ b _z (sin 7 cos ψ cos ç sin s sin ç + sin ç sin ψ cos 7 cos 7 cos ψ) ψ

And Φ (ί, ϊ ^' ) denotes an angle satisfying the equation:

Φ (ί, i) = arccos (<i / (t) Ι 2ό _χ ) - ψ - Az (t, i)

 the method comprises the steps of;

in a step, firstly determining a vertical displacement dh (t) of the observed motive moment t as a function of the coordinates of the lever arm B, bx, by, bz, Eulerian angles φ, θ, ψ, and the vertical displacement in translation dth (t) according to the equation:

dh (t) = {0 _x -b cos O - b sin _z cos b φήη θ- φήη Θ) + <p (b _y cos Θ RCC -b sin ç _z cos Θ) + dthit) and determine the pseudo? vertical corrected distance p _c ^h _orr (ί, ϊ) 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 pseudo-classical distance p _GPS (t , i), and the elevation angle El (t, i) of the satellite (Si) seen by the phase center (G) according to the expression:

Let (t, = PI _P S <A 0 + (0 + ² sgn (dh (t)) p _GPS (t, i) dh (t) sin (EL (i, /))

 where 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, b _x , b _y , b _z , Eulerian angles φ, θ, ψ according to the equation: dl = [(b _lx (- cos Θ sin ψ + cos Θ cos ψ)

+ b _ly (-cos i ψ + sin φήη #cos ψ - cos 77cos ψ + sin φήη θ ήη ψ)

+ b _lz (sin φ cos ψ - cos φ sin Θ sin ψ + sin φ sin ψ - cos φ sin Θ cos ψ) ψ

then, in the same step, determine the angle (ί, ί) 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, as a function of the horizontal displacement dl (t), the yaw angle ψ, the component b _x of the lever arm B ^b , and the angle d of the satellite Az (t, i) seen by the the phase center (G) of the antenna with respect to the direction of the geographic North, as follows:

Φ (ί, i) = arccos (<i / (t) I 2b _x ) - y / - Az (t, i)

then, in the same step, determine the horizontal corrected pseudo-distance p _c ^l _orr (t, 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 p _GPS (t, i) conventionally determined in a global positioning system between the phase center (G) and the satellite, the elevation angle El (t, i) of the satellite (Si) seen by the phase center (G) and the angle Φ (ί, ί), according to the expression: P Î _r = ÎPGPS ^cos2 + dl ² (t) - 2? _GP5 (t, <i / (t) cos (EL (t, i) cos Φ (ί,] / cos ² E / (t, in a step (236), determine a general pseudo-distance p _c ² _orr ( t, i) adjusted to the pseudorange corrected vertically p _c ^h _orr (t, i) and the pseudo-distance corrected horizontally p _œ ^the _rr (t, i), each associated with the same satellite (Si);

the corrected pseudo-general distance p _corr (t, i) is a function of the classical pseudorange p _GPS (t, i), the vertically corrected pseudo-distance p _c ^h _orr (t, i), and the pseudo-distance horizontally corrected distance p _c ^l _orr {t, i), each associated with the same satellite Si according to the expression:

P _ERAT (t, i) = P _GPS (t, i) + (P (t, i) - P _GPS (t, 0) + (p (M) _^"GPS P (t, 0)

the corrected pseudo-general distance p _corr (t, i) is an average of the vertically corrected pseudo-distance p _c ^h _orr (t, i) and of the horizontally corrected pseudo-distance p _m ' _rr (t, i) the average being selected from the set consisting of the average of the algebra, the mean of the barycentric, the geometric mean;

the radiolocation receiver, connected to a reception antenna, is bi-frequency adapted to receive signals at a first frequency f1 and at a second frequency f2 and comprises two phase centers (G1) and (G2) respectively associated with the first frequency f1 and at the second frequency f2; and the phase center (G) is the equivalent phase center (G _eq ) 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 relative to the direction of the geographic North,

correcting the equivalent phase center (G _eq ) a new equivalent phase center G _eq (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, determining the coordinates of a new lever arm B (Si) intended to be used in calculating the pseudo-distance corrected p _rrr (t, i) associated with the satellite

(Yes) ;

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 raw pseudo-distance data _GPS (t, i) as a function of the logical state of a reliability parameter (fiab (t)) of the inertial information, a function of time;

 the process comprises the steps of

 determining the angle of (Az (t, i)) of the satellite (Si) seen by the receiving antenna relative to the direction of the geographic north, and

 correcting the geometric effect called the 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 device comprising:

 a radiolocation receiver,

 a reception antenna connected to the radiolocation receiver, and having a phase center (G) associated with a frequency f1, the 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 frame (b) of the structure of the mobile, 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 instant t a plurality of radiolocation signals each transmitted at the frequency f1 by a transmitter of a different satellite , visible from the mobile, to process the received signals, to be determined conventionally, conventional raw information of pseudo-distances p _GPS (t, i) observed at time t, and supplying to a raw data memory the conventional raw information of pseudo-distances p _GPS (t, i) observed at the instant t,

 the inertial unit being able to supply 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,

 characterized in that it comprises a calculator adapted to:

first, for each fixed satellite (Si), determine the elevation angle (El (t, i)) under which the satellite (Si) is seen from the phase center (G) of the receiver antenna in function of the global positioning coordinates of the satellite (Si) and of 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 (p _GPS (t, i)) associated with the satellites,

correct each pseudo-gross distance (p _GPS (t, i)) in a corrected pseudo-distance p _mrr (t, i) corresponding to the function of the pseudo-gross distance (p _GPS (t, i)), current inertial information , the elevation angle (El (t, i)), and

then, to determine the geodesic local positioning of the mobile in the local geodesic locator-ll according to a conventional multi-latency method starting from the corrected pseudo-distances p _mrr (t, i) as new raw data, each of the pseudo-distances corrected for 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:

- Figure 1 is a sectional view of a marine buoy on which is mounted a positioning device according to the invention, FIG. 2 is a view of a set of reference marks in which the position and / or attitude coordinates of the buoy of FIG. 1 are determined,

 FIGS. 3, 4 and 5 are views defining 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 of the positioning device operating with a GPS radiolocation system,

 FIG. 7 is a flow chart of a method of positioning the buoy,

 - Figure 8 is a geometric representation of the vertical displacement of the buoy and pseudo-distance vertically corrected in a local geodesic landmark;

 - Figure 9 a geometric representation of horizontal displacement and the pseudo-distance corrected horizontally in the local geodesic coordinate system;

 FIG. 10 is a geometrical 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;

 - Figure 1 1 is a graphical representation of any displacement of the buoy with a horizontal component and a vertical component, and the pseudo-distance corrected 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 reception of two-frequency radiolocation signals with an antenna having two phase centers,

FIG. 13 is a 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 of a second time series at the same moments of the vertical positrons of the buoy. calculated from measurements of pseudo-distances determined according to the method of the invention, and FIG. 14 is a comparative view of the statistics of the short-period accuracy of the vertical position measurements of the buoy described in FIG. 13 following 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 1, 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 rigid hollow flange 22, of a toroidal shape and filled with air, sandwiched and fixed between a circular rigid lower floor 24 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 shaped of 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 housings by means of screws not shown.

The inertial unit 8 comprises a reference point P origin of three gyroscopic axes x ^p , y ^p , z ^p 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 measuring 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 fixing screws passing through the tabs of the second stage 12.

 The GPS radiolocation receiver 14 and the hybrid processing and integration unit 16 are fixed to the upper floor 30 of the first stage 6 by their respective housings by means of screws not shown in FIG. 1.

 The radiocommunication transmitter 11 with an integrated transmitting antenna on its upper face is fixed on the upper floor 30 outside the second stage 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 a high radio-frequency permittivity, is fixed along the periphery of the upper floor 38 of the second stage 12 by screws and fixing lugs, a seal being deposited between the periphery of the cupola 20 and the upper floor 38.

 The vector B connecting the phase reference center G of the GPS antenna

18 at the reference point P of the inertial unit 8 is called lever arm associated with the L1 phase.

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 Ω which is the center of mass O of the Earth at a reference moment ti ₀ , an axis x ¹ , pointing to the true vernal equinox (ascending node between the celestial equator and the ecliptic ) contained in the equatorial plane, a z ¹ axis coincides with the axis of Earth's rotation means at the time tio the 1 ^st January 2000 1 2:00 UT (Universal time), a y-axis' filling directly the mark inertial.

The reference-e comprises the origin O center of mass of the Earth, an axis x ^e contained in the plane of the equator and passing through the point of intersection of the equator with the meridian of Greenwich, point by which in forward direction equatorial longitudes are measured, an axis z ^e parallel to the mean terrestrial rotation axis of the reference ellipsoid defined in the WGS 84 system (World Geodetic System denomination of 1 984), an axis y ^e filling directly the e-mark.

 The e-mark is the GPS positioning reference of the GPS constellation.

 The reference-ll 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 N-mark is linked to the mobile, here at the reference point P of the inertial unit and moves with the buoy 2.

 The ll-mark comprises an axis z "which is normal to the reference ellipsoid of the Earth, an axis x" directed to the geodetic east direction and tangent to the local meridian, and an axis y "directed to the North supplementing directly the marker-ll.

The reference-ll is useful not to provide the coordinates of the mobile but to provide the components in the local directions that is to say the North, East and vertical, the buoy velocity vector and / or still the orientation or attitude of it. The directions of the marker-ll intervene in the determination of the rotation matrix (C _a ) of passage of the reference-N to the mark-e.

The reference-b is a mark arbitrarily fixed to the buoy whose origin coincides with the origin of the geodetic local coordinate system N, here the reference center P of the inertial unit. Here, the marker of the buoy comprises a z-axis ^b of said above, an x-axis ^b said front or prou and a y-axis ^b of said left or port side directly filling the mark-b of the 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 x ^p , y ^p , z ^p on the x ^b , y ^b , z ^b axes of the mark b of the buoy 2.

According to FIGS. 3, 4, 5, the orientation of the buoy 2, also called the attitude, is defined by three angles of Euler φ, θ, ψ linking the reference-b with respect to the reference gyroscopic axes x ^p , y ^p , z ^p of the inertial unit 8 and the mark-ll 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 φ, illustrated in Figure 3 and called in English "roll", is the angle of roll which rotates the buoy 2 about the axis x ^b .

The second angle of Euler designated by the letter Θ, illustrated in Figure 4 and called in English "pitch" is the pitch angle of which the buoy 2 around the y axis ^b .

The third angle of Euler designated by the letter ψ, 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 axis z ^b .

 The attitude variations φ, θ, ψ respectively correspond to angular velocities ωζ 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 1 00 comprises the reception antenna 1 8 of the GPS signals, the GPS radiolocation receiver 14, a coaxial link 1 02 connecting the antenna 1 8 and the receiver 14, the inertial unit 8 , the hybrid processing and integration unit 1 6 position information and the attitude of the buoy 2, the 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, connected to the battery 10 and supplying respectively the radiolocation receiver 14, the inertial unit 8 and the processing unit. and hybrid integration 16.

 The phase center 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 carrier 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 radiofrequency (RF) reception chain 1 10 intended to amplify, filter and convert the frequency of the GPS signal received at the antenna 18,

 a conversion unit 1 12 comprising a not shown analog-to-digital converter (ADC) coupled to an automatic gain control (AGC) chain, also not shown,

 a signal processing unit 1 14 able to demodulate the digital signal coming from the conversion unit 1 12 into data and to make raw measurements of pseudo-distances and / or of phases Φ (ί) and / or speeds and / or angles.

The radiolocation receiver 14 also comprises a clock 1 16 connected at a first input 1 18 to the reception channel 1 10 to provide a reference frequency to slave to the received GPS signal. The clock 1 16 is also connected to a second input 120, respectively to a third input 1 22, to the conversion unit 1 1 2, respectively to the signal processing unit 1 14, to provide the units 1 1 2, 1 14 time marks and associated dates.

 The inertial unit 8 comprises a control input 1 30, able to receive calibration data and an initialization command at a reference position provided by an input member 1 31 represented by a dotted outline, an output 1 32 adapted to provide angles of attitude, the coordinates in the reference-b of the buoy lever arm B formed by the vector connecting the reference point P of the inertial unit 8 at 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 is here a SINS (Strap down INertiel System) connected component central unit comprising three very bright 1 34, 1 36, 1 38, here optical laser (called Fiber Optical 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 co _m ^b are designated respectively by ω, ω, o _c ^b according to the normals n _A ^b , n _B ^b , n _c ^b 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. t ₀ at eulerian angles cp (tk), 9 (tk), ijj (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 angles Eulerian and vertical displacement in translation at times t _k . 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 capable of recording a predetermined matrix for passing from the p-mark to the b-mark designated C _P ^b and the coordinates of the lever arm B ^b in the mark b of the buoy 2 provided by the control member. entrance 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 C _p ^b provided by the calibration memory 140, to correct bias errors, scale, and orthogonality due to 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-ll.

The correction unit 144 is able to provide an angular velocity of the reference mark -b around the reference-ll with components in the reference-b said corrected, designated by co _m ^h , by multiplying the same vector a> f _lb whose components are in the p-mark by the correction matrix C _p ^b .

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 to a predetermined sampling time t _k with respect to an initial reference time t ₀ , with t _k equal to the sum of t ₀ and k times a sampling period designated by T _eC h.

The integration unit 144 is able to initialize at time t ₀ , the Eulerian angular output variables cp (t ₀ ), θ (ΐ ₀ ), ψ (ΐ ₀ ) to zero when receiving a signal. if- initialization control signal received at the first input 164 and transmitted from the calibration memory 140.

The angular integration unit 144 is able to integrate in time slice on the sampling time T _eC h the corrected angular velocity ω in Euler angle measurements (p (t _k- -i, t _k ), G (t _k -i, t _k ), ψ (ΐκ - ι, t _k ) traveled between instants t _k- 1 and t _k , the instant t _k of rank k succeeding the sampling instant t _k -i previous of rank k-1, with t _k equal to the sum of t _k -i and T _eC h, and to calculate at each successive moment t _k the angles of Euler according to the equations:

cp (t _k ) = ⁽ P (t _k -i, t _k ) + cp (t _k -i),

9 (t _k ) = e (t _k -i, tk) + 9 (t _k -i), and

i | ^j (tk) = i | ^j (t _k -i, t _k ) + i | ^j (t _k -i).

 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 connected 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 able to receive the coordinates of the lever arm B ^B 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 z-axis ", and the Euler angles cp (t _k), 9 (t _k), ijj (t _k) calculated at each subsequent instant t _k.

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 B ^B 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 (t _k), 9 (t _k), ψ (ίκ) calculated at each subsequent instant t _k.

 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 able to receive the coordinates of the lever arm B _G 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 t _k , the displacement of the buoy according to the local vertical, the coordinates of the lever arm B in the mark -b of the buoy, the where appropriate, the coordinates of the lever arm B _G ^b 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 the RINEX type standard.

 The input memory 188 is able to receive satellite positioning data Si, i ranging from 1 to n, where n is the maximum number of channels of the buoy radiolocation 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 adapted to execute a set of instructions forming a computer program provided from a recording medium not shown in FIG. 6.

The computer 190 is able to determine by a conventional global positioning method the positioning of the phase center G of the antenna of the buoy 2 receiver from the conventional raw data of pseudoranges and / or phase associated with each satellite and global positioning data Si satellites.

 The computer 190 is able to determine, for each satellite Si, the elevation angle of the satellite Si seen from the center of phase G from the global positioning coordinates of the phase center G of the antenna determined by a conventional method of global positioning and from the global positioning coordinates of the satellite Si.

 The computer 190 is able to determine for each satellite If 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 pseudo-distance or phase-like raw data into a new corrected raw raw data without having combined with each other. the conventional raw data including 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 1 1 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 calculator 190 for delayed processing.

 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 with a degree of freedom capable of detecting 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 direction to the North 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 capable of sending the data stored in the storage and retrieval unit through a radio link in real time or in deferred time. data 10.

 According to FIG. 7, a method of positioning or dynamic location of the buoy 2 comprises a first succession 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 the alignment step, an operator aligns the orientation of the sensitive axes of the gyroscopes x ^p , y ^p , z ^p of the reference-p of the inertial unit with respect to the reference -b linked to the rigid structure of buoy 2 and / or relative to the N-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 G _G of the buoy 2, the fixed reference point P of the inertial unit 8 are accurately determined by an optical method using tacheometers. and / or a method using a radiolocation benchmarking base, in the b-coordinate system or in the N-coordinate system which has also been accurately 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 measurements and calibration data, the correction matrix

C _p ^b is determined for a b-mark aligned with the -N mark.

The correction matrix C _p ^b , the coordinates of the lever arms B ^b are loaded into the calibration memory 140.

In the initialization and synchronization step 206, at an initialization time t ₀ , an initialization control signal is emitted by the calibration memory 140 and then the integration unit 144 calculates the angular variables. initial eulerian output cp (t ₀ ), θ (ΐ ₀ ), ψ (ΐ ₀ ) to zero. This procedure refers to the procedure of leveling the inertial unit called "levellings". At time t _0, the b-mark linked to the tag 2 and the-ll mark are aligned.

In the same step 206 of initialization and synchronization, at time t ₀ the clock 1 1 6 of the receiver 14 is synchronized with the Si GPS satellite clocks with different clock offsets according to each satellite Si. Each respective phase Oi (t ₀ ) 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 can be processed. the receiver 14.

 In a next step 208, two steps 21 6 and 21 8 are executed successively.

In the step 21 6, at the time of measurement t, for each satellite Si, i ranging from 1 to n, the phase Oi (t) and / or a propagation time r _; (t) a signal, emitted by the satellite Si, between the satellite Si and the center of phase G, is measured for a moment t of reception at the buoy.

p _GPS (t, i) generically designates the classical pseudo-gross distance, calculated from Oi (t) and / or f _; (t), separating the satellite Si from the center of phase G.

 For i varying from 1 to n, each phase Oi (t) expressed in number of cycles can be converted into a pseudo-spatial distance Li (t) defined by the equation:

- Φί(ί₀)] = p_GPS (t, i) où λι désigne la longueur d'onde de la porteuse à la fréquence f1 . L i (t) =

- Φί (ί ₀ )] = p _GPS (t, i) where λι 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) = cT _i (t) = p _GPS (t, i)

 where c is the speed of light in a 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 offset _i that the replica must undergo in order to with the received code corresponds to the propagation time that the signal has put to traverse the distance separating the satellite Si to the receiver at the instant 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 Oi (t) of the carrier wave at the frequency f1 consists in 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 1 1 6 and theoretically, this phase difference oscillates between 0 and 2π.

Thus, the phase difference measurement Oi (t) - Oi (t ₀ ) can be interpreted as an accurate measurement of the variation of the receiver distance 14 (phase center G1) - satellite Si since the initial time t ₀ . The resolution of a phase measurement can reach a few millimeters.

It is sufficient that one of the magnitudes f _; (t), Oi (t), Li (t), Pi (t) is supplied to the raw data input memory 188 as an observable to be able to determine the conventional raw pseudo-distance g _GPS (t , i).

For example, the observable Oi (t) is supplied to the raw data input memory 188 as a number of cycles, the number having an integer portion and a fractional portion. In particular, when the receiver 14 has acquired the phase of the GPS signal received for example with a Costas loop, the initial phase Oi (t ₀ ) for each index value i is set to zero.

 In the same step 6 6, the receiver receives at time t the GPS coordinates of each satellite Si supplier of the radiolocation signals buoy 2 corresponding to the time of reception t. These coordinates are regularly broadcast by the satellites of the constellation.

These coordinates for i fixed are for example the longitude designated by Ā _GPS (t, i), the latitude designated by <i> _GPS (t, i) e. the height designated by h _GPS (t, i).

In step 218, one of the magnitudes f _; (t), Oi (t), Li (t), Pi (t) is supplied to the raw data input memory 188 as an observer to determine the conventional gross pseudo- _GPS distance (t, i). respective associated with a separate satellite Si.

 In the same step 21 8, the global positioning coordinates of each satellite Si providing the radiolocation signals of the buoy 2 and corresponding to an instant sufficiently close to or equal to the instant t are provided to the input memory 188 of data gross.

 In step 210, executed in parallel with step 208, the inertial unit 8 determines the coordinates of the lever arm B "in the reference-ll.

 Step 21 0 comprises a sequence of steps 220, 222, 224 and 226,

In step 220, the correction unit transforms the vector of the angular variations provided by the gyrometers in the b-frame by multiplying it by the rotation matrix C _P ^b resulting from the geometrical calibration.

In step 222, the angular integration unit 1 44 integrates the corrected angular velocity vectors emitted by the correction unit between the initial time t ₀ and the sampling time tk internal to the unit d. integration 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 corresponding Eulerian angles cp (t), θ (ΐ), ψ (ΐ).

In the same step 222, the vertical accelerometer 35 determines the vertical translational displacement of the buoy 2 designated by dth (t) by a double in- 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 inertial data transfer unit 148 receives the coordinates of the lever arm B ^b emitted from the calibration and initialization memory 140, the Eulerian angles cp (t), θ (ΐ), ψ (ΐ) provided by the angular integration unit 144 and the vertical translation displacement 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 B ^b designated b _x , b _y , b _z in the b-mark of the buoy, the values of Eulerian angles φ, Θ, ψ considered at time t, and the vertical displacement in translation of the buoy 2 dth (t), called in English "heave".

In the same step 226, the input memory 188 receives the coordinates of the lever arm B _G ^b from the input member 131.

In a variant, the provision of the coordinates of the lever arm B _G ^b to the input memory 188 is performed once at the same time as the initialization step 206.

In step 212, for each satellite Si of index i, a corrected gross pseudo-distance pt _rr (t, i) is computed as a function of the pseudo-classical distance p _GPS (t, i) associated with the same satellite Si , Eulerian gyroscopic angles considered at the same time t and designated respectively by φ, θ, ψ, the vertical displacement displacement of the buoy 2, dth (t), the 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 G center of the antenna in the positioning system global, here GPS from the pseudo-classical distances _GPS p (t, i) associated with satellites Si, i ranging 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.

 Also known, the calculator determines for each satellite Si the angle of the satellite seen by the center of phase G of the antenna relative to the direction of the geographical 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) depending on the coordinates of lever arm B, bx, by, bz, Eulerian angles φ, θ, ψ observed at the moment t, and of the vertical displacement in translation dth (t) according to the equation: dh (t) = 6-b _x cos O -b sin ç m O-b _z cos ç? sin Θ ) + <p (b _y cos çcos Θ -b _z sin ç cos Θ) + dth (t) Then, in the same step 232, the calculator determines the vertical corrected pseudorange p _c ^h _orr (ί, ϊ) associated with the satellite Si as a function of the vertical displacement of the buoy calculated and observed at time t, dh (t), of the classical pseudo-distance _GPS (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 elevation angle El (t, i) of the satellite Si seen by the center of phase G according to the expression:

Let (* * *) = PIPS <A 0 + (0 + ² sgn (dh (t)) p _GPS (t, i) dh (t) sm (EL (t, i))

 where 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 _G ² _PS (t, i) +

{{-B _× cos θ - b _ly sin φ η θ - _lz b cos φ η θ) + ç {b _ly cos Θ RCC _lz -b sin #> cos #) + ώ¾) ²

+ 2 sgn (A)? _GPi , i) sin (EL (t, i)) (0 (-b _ix cos Θ - b _ly sin çsin Θ - b _lz cos #> sin #) + cos #> cos Θ

-b sin #> cos Θ) + 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 lever arm B, bx, by, bz, Eulerian angles φ, θ, ψ according to the equation: dl = [(b _lx (- cos Θ sin ψ + cos Θ cos ψ)

+ b _ly (- cos i ψ + sin φήη # cos ψ - cos cos ψ + sin φ ήη # sin ψ)

+ b _lz (sin φ cos ψ - cos φ sin θ ήη ψ + sin sin ψ - cos sin Θ cos ^)] ^ ^"

 Then, in the same step 234, the calculator determines the angle, denoted by <i> (Y, and formed between the direction of the horizontal projection of the phase center line G-satellite Si and the direction of the horizontal displacement dl (t) of the buoy 2, as a function of the horizontal displacement dl (t), the yaw angle ψ, 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 relative to the direction of the geographic North, as follows:

Φ (ί, ï) = arccos (<i / (12b _x ) - y / - Az (t, i)

Then, in the same step 234, the computer determines the horizontal corrected pseudorange p _m ' _rr (ί, ϊ) associated with the satellite Si as a function of the horizontal displacement of the buoy 2 calculated and observed at time t, dl (t) , of the classical pseudo-distance _GPS (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 satellite Si seen by the center of phase G and the angle Φ (ί, ί), according to the expression:

P rr (> *) = PGPS ^{cos2 El} (t _> + d1 ² (t) - 2p _GPS (t, i) dl {t) cos (EL (t, i) cos Φ (ί, i)] I cos ² E / (t, i) The geometric representation of the expression the horizontal corrected pseudo-distance p _c ' _o ² _rr (t, i) is described in FIG. 9 as the relations existing between the sides of the triangles (A, Si, C) and (A, If, B).

 The geometric representation of the expression Φ (Υ, is described in Figure 10 as the relations existing between the sides of the triangles (A, B, D) and (A, B, C).

The detailed expression of the horizontal pseudo-distance p _c ^l _orr {t, I) associated with the corrected If satellite is:

P _GPS ^cos El (t, i) +

[b _lx {-cos θ η ψ + cos Θ cos ψ) + b _ly (- cos if ψ + sin if Θ cos ψ

- cos φ cos ψ + sin φ sin Θ sin ψ) + b _lz (sin φ cos ψ - cos φ sin Θ sin ψ

Ρ _ο Λ ^ Ϊ) = + sin φ sin ψ - cos φ sin Θ cos ψ)] ² ψ ² / cos El {t, i)

- 2p _GPS (t, i) cos (EL (t, i) cos Φ (ί, ί) ψ [φ _ίχ (- cos Θ sin ψ + cos Θ cos ψ)

+ b _ly (- cos (p sin ψ + sin sin Θ cos - cos cos + sin (p sin ^ sin ψ)

+ b _lz (sin cos ψ - cos sin Θ sin + sin sin - cos (p sin # cos ç))

In step 236, the calculator determines the pseudo-general corrected distance designated by p ² _orr (t, i), associated with the satellite Si, the vertical displacement and the horizontal displacement respectively determined in step 232 and in step 234.

The general pseudo-distance p ² _orr (t, i) associated with the satellite is determined as a function of the pseudo-classical distance p _GPS (t, i), the vertically corrected pseudo-distance p _c ^h _orr {t, ï), the pseudo-distance corrected horizontally p _c ^l _orr (t, i), each associated with the same satellite, according to the expression:

P (t, i) = PG _P S (t, 0 + (p (t, - P _GPS (t, 0) + (p (t, 0 - P _GPS (t, 0)

As a variant, the general pseudo-distance p _corr (t, ï) is an average of the vertically corrected pseudo-distance ρ _c ^h _orr (t, ï) and of the horizontally corrected pseudo-distance p ^l _{c orr} (t, i ), the average being chosen from the set constituted by the average algebraic, the mean barycentric, the geometric mean. In step 214, the positioning of the buoy 2 is determined by a conventional method from the corrected pseudo-distances p _corr (t, i) according to the invention, for i varying 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 corresponding to the corrected pseudo-distances p _corr (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 adapted to receive 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, denoted G _eq , 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 make it possible conventionally to correct the position of the equivalent phase center G _eq .

The position of the equivalent phase center G _eq is thus a function for a given satellite Si of the associated elevation El (t, i) and 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 positioning method 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 31 1 with two outputs.

 Depending on the output of test step 31 1, a step 312 or 313 is implemented, each followed by step 214.

Step 304 is step 204 in which the center of phase G described in FIG. 1 is the equivalent phase center G _eq obtained by reduction of the phase centers G1 and G2.

 Step 310 includes the same steps 220, 224, 226 as step 210 except for step 322 which replaces step 222.

In step 322, the same tasks as step 222 are performed in particular. In step 322, the inertial unit 18 is able, from the measurement data provided by the accelerometer 35 and / or the unit. 144 to estimate a parameter of reliability of the inertial information, time function and designated by fiab (t), in view of the decision of future use of the inertial data in the conventional raw data correction algorithm p _GPS (t , i) pseudo-distance, or with a view to their non-use and the 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 φ, θ, ψ and / or of displacement in translation dth are non-existent, which corresponds to a "hole", or else erroneous by the highlighting drifts or offsets of excessive instruments.

 Steps 216 and 218 are executed identically to those of method 100.

 Step 31 1 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 indicates a lack of reliability of the inertial information coming from the inertial unit 8, then the steps of correction of the pseudo-distance raw data _GPS (t, i) for each of the satellites Si in function inertial information is not executed and only the pseudo-distances p _GPS (t, i) determined by 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 p _GPS (t, i) of pseudo-distances not corrected by the 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 in translation.

 When a second state of the reliability parameter reflects the presence of reliability of the inertial information, then the correction step 312 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 G _eq is corrected in knowledge function for each satellite Si of the associated elevation El (t, i) and 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 separate lever arm B (Si) corresponding and to provide new lever arm coordinates B (Si) for the implementation of the following steps 232, 234.

 The advantage of choosing 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 the frequencies f 1 and f 2 is that the corresponding pseudo-distances and phase observations can be corrected finely 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 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 with respect to the average of the measurements on a short period of observation, precisely on slippery windows of 120 seconds.

 According to Figure 14, the statistics of the accuracies of the measurements of the vertical buoy positions described by the curves in Figure 1 3 reflect the reliability and the stability of the measurements over a short period of observation.

 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 shows a reduction of the measurement noise by a factor of 10.

 Alternatively, the increase in observations may be made by measurements of ground reference stations retransmitted to the buoy radiolocation receiver 14.

 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.

 Consequently, 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 Oi (t) can be corrected additionally. to become a pseudo-distance corrected more precisely.

Claims

1. 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 phase center (G) associated with a frequency f1, the receiving antenna (18) being fixed with respect to the structure of the mobile (2) ), and  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),  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 different satellite (50, 52, 54, 56), visible from the mobile (2), processing the received signals and conventionally determining (208) conventional raw information of pseudo-distances p _GPS (t, i) observed at time t, providing (208) by the radiolocation receiver to a raw data memory (188) the conventional raw information of pseudo-distances P _GPS () observed at time t,  providing (226) by the inertial unit (8) to the raw data memory (188) at the instant t of observation of the current inertial information associated with the instant t of the mobile (2) with respect to a local geodetic reference,  characterized in that it comprises the steps of:  first, for each fixed satellite (Si), determining (230) the elevation angle (El (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 global position of the phase center (G), the global position of the phase center (G) being determined as a function of the conventional pseudo-gross distances p _GPS (t, i) associated with the satellites (50, 52, 54, 56), correct (236) each raw pseudo-distance p _GPS (t, i) to a corrected pseudorange p _corr (t, i) corresponding to the pseudo-gross distance p _GPS (t, i), current inertial information, elevation angle (El (t, i)), Next, determine (214) the geodesic local positioning of the mobile in the local geodesic locator-ll according to a conventional multiresolution process from the corrected pseudo-distances _corr (t, i) as new raw data, each of pseudo-corrected 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) Eulerian angles φ, θ, ψ, respectively called roll, pitch and yaw, of transformation of the directions of the reference-b linked to the mobile (2) in directions of the local geodetic locator 11 and to be determined from a local vertical accelerometer (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 includes the angles of transformation φ, Θ, ψ at the instant t, the displacement dth (t) in translation of the mobile (2) according to the local vertical and the coordinates b _x , b _y , b _z of a lever arm vector (B ^b ) in the b-mark of the mobile (2), the lever arm vector (B ^b ) 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),  Dynamic location method according to claim 2, characterized in that the corrected pseudo-distance satisfies the equation: p] _orr (t, i) = p _G ² _PS (t, i) + dh ² (t) + 2 sgn (dh (t)) p _GPS (t, i) dh (t) sin (EL (i, 0) where sgn (.) denotes the sign function and dh (t) satisfies the equation dh (t) = 0 {-b _x cos Θ -b sin φήη Θ -b _z cos φήη Θ) + <p (b _y cos O -b _z sin çcos Θ) + dth (t) 4. Dynamic location method according to claim 1, characterized in that it comprises the steps of  determine 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) with respect to the direction of the Geographic North, for each satellite (Si), correcting the conventional pseudo-gross distance (p _GPS (t, i)) associated with a corrected pseudo-distance (? _COTr (t,) corresponding to the function of the classical pseudo-gross distance (p _GPS ( t, i)), current inertial information, the 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 the angles of transformation φ, θ, ψ of the directions of the reference-b connected to the mobile (2) in directions of the local geodetic reference-11, and the current inertial information including the angles of transformation φ, θ, ψ at time t, the coordinates of a leverage vector (B ^b ) in the reference-b of the mobile (2), b _x , b _y , b _z , the leverage vector (B ^b ) 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) ,  Dynamic locating method according to claim 4, characterized in that the corrected pseudo-distance satisfies the equation: P ^{ _rr ( ^{ _> = -PI _PS ( ^{ _> ^{cos2 E} t, 0 + dl ² (t) - 2p _GPS (t, i) dl (t) cos (EL (t, i) cos Φ (ί, i) ] / cos ² El (t, In which d1 denotes a displacement satisfying the equation  dl (t) = [(^ (-cos tf sin ^ + cos <9cos ^) + b _y (- cos φ sin ψ + sin φ sin Θ cos ψ - cos φ cos ψ + sin φ sin Θ sin ψ) + b _z (sin 77cos ψ cos ç sin ssin ψ + sin φήη ψ cos cos sin cos ψ) ψ And Φ (ί, ϊ ^' ) denotes an angle satisfying the equation: Φ (ί, i) = arccos (<i / (t) Ι 2ό _χ ) - ψ - Az (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 φ, θ , ψ, and of the vertical displacement in translation dth (t) according to the equation: dh (t) = 6-b _x cos? e -? b sin φήη θ- b _z cos φ sin Θ) + <p (b _y cos Θ RCC -b sin ç _z cos Θ) + dth (t) and determining the vertical corrected pseudo-distance p _c ^h _orr associated with the satellite (Si) as a function of the vertical displacement (dh (t)) of the mobile (2) determined and observed at time t, of the pseudo-classical distance _GPS (t, i), and of the elevation angle El (t, i) of the satellite (Si) seen by the following phase center (G) the expression: P _c L (t, i) = PI _PS <A 0 + dh ² (t) + 2 sgn (dh (t)) p _GPS (t, i) dh (t) sin (EL (i, 0)  where sgn (.) designates 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 and a function of the coordinates of the lever arm B, b _x , b _y , b _z , angles Eulerian φ, θ, ψ according to the equation: dl = [(b _lx (- cos Θ sin ψ + cos Θ cos ψ) + b _ly (-cos i ψ + sin φήη # cos ψ - cos cos ψ + sin φήη # sin ψ) + b _lz (sin φ cos ψ - cos φ sin Θ sin ψ + sin φ sin ψ - cos φ sin Θ cos ψ) ψ then, in the same step (234), determining the angle Φ (ί,) 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 ψ, the component b _x of the lever arm B ^b , and the angle d of the satellite Az (t , i) seen by the phase center (G) of the antenna (18) relative to the direction of the geographic North, as follows: Φ (ί, i) = arccos (<i / (t) Ι 2ό _χ ) - ψ - Az (t, i) then, in the same step (234), determining the pseudo-corrected horizontal distance p _m ' _rr (ί, ϊ) associated with the satellite (Si) as a function of the horizontal displacement dl (t) of the mobile (2) determined at the instant t, of the pseudo-classical distance _GPS (t, i) conventionally determined in a global positioning system between the phase center (G) and the satellite, of the elevation angle El (t, i ) of the satellite (Si) seen by the phase center (G) and the angle Φ (ί, ϊ), according to the expression: Pit _rr = IP _GPS ^{cos2 El} (^ + (t) - ^ P _GFS (t, i) dl {t) cos (EL (t, i) cos Φ (ί, i)] I cos ² E / (t, i) in a step (236), determining a general pseudo-distance p _c ² _orr (t, i) corrected according to the vertically corrected pseudo-distance p _c ^h _orr (t, i) and the pseudo-distance corrected horizontally p _c ^l _orr {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 p _corr (t, ï) corrected is a function of the pseudo-distance classical p _GPS (t, i) , of the vertically corrected pseudo-distance p _c ^h _orr (t, i), and of the pseudo-distance corrected horizontally p _c ^l _orr {t, i), each associated with the same satellite Si according to the expression:. Pcrr C = P GPS C + (PC ^" P GPS C 0) + (p C ^" P GPS C 0) ^■  8. A method of dynamically locating a mobile (2) according to claim 6, characterized in that the corrected pseudo-general distance p _corr (t, i) is an average of the vertically corrected pseudo-distance p _c ^h _orr (t, i) and of the pseudo-distance corrected horizontally p _c ^l _orr (t, i), the average being selected from the set consisting of the average algebraic, the average 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) associated respectively with the first frequency f1 and the second frequency f2; and in that the phase center (G) is the equivalent phase center (G _eq ) obtained by reduction of 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 (G _eq ) a new equivalent phase center G _eq (Si) depending on the elevation angle (El (t, i)) under which the satellite (Si) is seen from the antenna receiving (18), the angle of (Az (t, i)) of the satellite (Si) seen by the receiving antenna (18) relative to the direction of the geographic North, determining the coordinates of a new lever arm B (Si) intended to be used in calculating the corrected pseudo-distance p _corr (t) associated with the satellite (Si). 1 1. Dynamic locating method according to any one of claims 1 to 10, characterized in that it comprises a decision step (31 1) of the subsequent use or not of the current inertial data acquired in the step ( 208), in the step of correcting the conventional pseudo-distance _GPS raw data (t, i) as a function of the logical state of a reliability parameter (fiab (t)) inertial information, a function of time.  12. Dynamic locating method according to any one of claims 1 to 1 1, 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) relative to the direction of the geographic North, and  correcting the geometric effect called the English "windup phase" from the knowledge of the relative position of the receiving antenna (18) with respect to the geographic 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 receiving 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 with respect 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 able to receive, 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 émet- of a different satellite (50, 52, 54, 56), visible from the mobile (2), to process the received signals, to conventionally determine conventional raw information of pseudo-distances p _GPS (t, i) observed at time t, and supplying (208) to a raw data memory (188) the conventional raw information of pseudo-distances _GPS (t, i) observed at time t,  the inertial unit (8) being able to supply the raw data memory (188) at the instant t of observation with current inertial information associated with the instant t of the mobile (2) with respect to a local geodetic reference,  characterized in that it comprises a calculator adapted to:  first, for each satellite (Si) fixed, determine the elevation angle (El (t, i)) under which the satellite (Si) is seen 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 center of phase (G), the overall position of the phase center (G) being determined according to the conventional pseudo-gross distances (Pcps it 'i)) associated with the satellites (50, 52, 54, 56), correct each pseudo-gross distance (p _GPS (t, i)) to a corrected pseudo-distance p _corr (t, ï) corresponding to the function of the pseudo-gross distance (p _GPS (t, i)), current inertial information , the elevation angle (El (t, i)), and then, to determine the geodesic local positioning of the mobile in the local geodesic locator-ll following a conventional multi-latency procedure from the corrected pseudo-distances p _corr (t, i) as new raw data, each of the pseudo-distances corrected for a different satellite (Si).  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.