초록 ▼

The invention pertains to the monitoring of the integrity of position and speed information arising from a hybridization between an inertial reference system and a satellite-based positioning receiver. The invention relates more precisely to a navigation apparatus known in the art by the name INS/GN

The invention pertains to the monitoring of the integrity of position and speed information arising from a hybridization between an inertial reference system and a satellite-based positioning receiver. The invention relates more precisely to a navigation apparatus known in the art by the name INS/GNSS system (for “Inertial Navigation System” and “Global Navigation Satellite System”) hybridized in closed loop.

대표청구항 ▼

The invention claimed is: 1. A INS/GNSS hybrid system with integrity monitoring, comprising: a barometric module BARO delivering measurements of barometric altitude MBA; an inertial measurement unit UMI delivering angle increments Δθ and speed increments ΔV; a virtual platform PFV

The invention claimed is: 1. A INS/GNSS hybrid system with integrity monitoring, comprising: a barometric module BARO delivering measurements of barometric altitude MBA; an inertial measurement unit UMI delivering angle increments Δθ and speed increments ΔV; a virtual platform PFV receiving the angle increments Δθ, the speed increments ΔV and producing inertial positioning and speed data PPVI constituting respectively a hybrid position and a hybrid speed; a satellite-based positioning receiver GNSS operating on the basis of a constellation of N tracked visible satellites, and producing raw measurements, MBi of the signals transmitted by these satellites, i denoting a satellite index and lying between 1 and N; a Kalman hybridization filter MKF receiving the inertial positioning and speed data PPVI, the measurements of barometric altitude MBA, and the raw measurements MBi of the signals transmitted by the N satellites, said filter delivering: a hybrid correction HYC comprising an estimation of a state vector VE corresponding to the errors of the hybrid system and obtained by observing the deviations between the inertial positioning and speed data PPVI and the raw measurements MBi, and a variance/covariance matrix MHYP of the error made in the estimation of the state vector VE; a bank of N secondary filters KSFi each receiving the inertial positioning and speed PPVI, the measurements of barometric altitude MBA, and the raw measurements MBi of the signals transmitted by the tracked satellites except the satellite of index i, said secondary filters KSFi delivering hybrid parameters SHYPi comprising an estimation of a state vector EVEi corresponding to the errors of the hybrid system, calculated by observing deviations between the inertial positioning and speed data PPVI and the raw measurements of the signals transmitted by the tracked satellites except the satellite i SPPi, and a secondary variance/covariance matrix Pi of the error made in the estimation of the state vector EVEi; a calculation module CAL receiving the hybrid parameters SHYPi and the variance/covariance matrix, MHYP, said calculation module CAL determining a horizontal protection radius RT associated with the hybrid position, and, when components of the estimation of the state vector EVEi relating to the position are greater than a detection threshold THi, triggering an alarm upon a failure of a secondary filter KSFi, and optionally identifying a failed satellite from among the N tracked visible satellites, wherein the secondary filters KSFi and the virtual platform PFV furthermore receive the hybrid correction HYC. 2. The system as claimed in claim 1, wherein, when the calculation module CAL identifies the satellite of index i as having failed, the secondary filter KSFi is substituted for the Kalman filter MKF. 3. A method for determining a horizontal protection radius RPT for monitoring integrity of hybrid positions delivered by a virtual platform PFV of a hybrid system as claimed in claim 1, said method implemented by the calculation module CAL of the hybrid comprising the steps of: determining an auxiliary horizontal protection radius RPH1, under an hypothesis termed H1, that one of the raw measurements, MBi is erroneous, determining an auxiliary horizontal protection radius RPH0, under an hypothesis termed H0, that none of the raw measurements, MBi is erroneous; fixing the value of the horizontal protection radius RPT as a maximum of the horizontal auxiliary protection radii RPH0 and RPH1, wherein the determination of the auxiliary horizontal protection radii RPH0 and RPH1 is based on determining a radius of a circle enveloping a confidence ellipse in a horizontal plane, and in that the confidence ellipse is determined on the basis of a variance/covariance matrix and of a sought-after probability value. 4. The method as claimed in claim 3, wherein the determination of the auxiliary horizontal protection radius RPH1 is based on a desired false alarm probability value τ1 and on a desired missed detection probability value τ2. 5. The method as claimed in claim 3, wherein the determination of the auxiliary horizontal protection radius RPH0 is based on a desired missed detection probability value τ2 and on a value of probability of occurrence of an undetected satellite defect τ3. 6. The method as claimed in claim 4, wherein a variance/covariance matrix PEi, of dimension 2×2, is extracted from an auxiliary matrix PSi=Pi−MHYP with axes corresponding to the horizontal positions, and wherein the determination of the auxiliary horizontal protection radius RPH1 under the hypothesis H1, comprises the steps of: Determining P01=1−Σ1/N; Determining a test threshold value THi based on the value P01 and on the matrix PEi; Determining P02=1−τ2; Determining a value of auxiliary protection radius di as equal to the radius of the circle enveloping an ellipse determined on the basis of the matrix PEi and of the probability P02; Determining the radius value RPH0 as a maximum value of (THi+di), for all the values of i between 1 and N. 7. The method as claimed in claim 5, wherein a variance/covariance matrix P of dimension 2×2 being extracted from the variance/covariance matrix MHYP with axes corresponding to the horizontal positions, and wherein the determination of the auxiliary horizontal protection radius RPH0 under the hypothesis H0, comprises the steps of: determining P03=1−τ2·τ3; determining the radius value RPH0 as equal to the radius of the circle enveloping an ellipse determined on the basis of the matrix P and of the probability P03.