Abstract: A method of monitoring at least first and second inertial measurement units, the first inertial measurement unit and the second inertial measurement unit being connected to the same electronic processor circuit and being arranged to determine both a specific force vector in an accelerometer measurement reference frame and also rotation data concerning turning of the accelerometer measurement reference frame relative to an inertial reference frame; the electronic processor circuit performs the steps of projecting the specific force vectors into an inertial reference frame by using the rotation data; comparing the two specific force vectors as projected into said reference frame with each other in order to determine a difference between them; and monitoring variation in this difference over time.

Abstract: A method of monitoring at least first and second inertial measurement units, the first inertial measurement unit and the second inertial measurement unit being connected to the same electronic processor circuit and being arranged to determine both a specific force vector in an accelerometer measurement reference frame and also rotation data concerning turning of the accelerometer measurement reference frame relative to an inertial reference frame; the electronic processor circuit performs the steps of projecting the specific force vectors into an inertial reference frame by using the rotation data; comparing the two specific force vectors as projected into said reference frame with each other in order to determine a difference between them; and monitoring variation in this difference over time.

Abstract: A device for measuring rotation including an NMR gyroscope having a sensing axis, a computer, a generating member configured to generate a magnetic field directed along the sensing axis, and a MEMS gyroscope rigidly connected to the NMR gyroscope, the MEMS gyroscope having a sensing axis aligned with the sensing axis of the NMR gyroscope, the MEMS gyroscope being suitable for delivering a MEMS signal representing a rotation about the sensing axis, the computer being configured to calculate, from an NMR signal output by the NMR gyroscope, information relating to a rotation about the sensing axis, and to analyse the MEMS signal over time in order to determine a current cut-off frequency, the computer also being configured to control the generating member in order to generate, over time, a magnetic field of which the amplitude is a function of the current cut-off frequency.

Abstract: The invention relates to a navigational aid method for an inertial navigation system including at least one inertial sensor (4) having a sensitive axis (X-X), each inertial sensor (4) comprising an ASG gyroscope (8) able to deliver an ASG signal representative of a rotation about the corresponding sensitive axis (X-X), and a MEMS gyroscope (10) able to deliver a MEMS signal representative of a rotation about the corresponding sensitive axis (X-X), the method including the steps of: between a first date and a subsequent third date, calculating a path from the MEMS signals; from the third date, calculating the path from the ASG signals; estimating a bias vector introduced by the MEMS gyroscopes (10), from the MEMS signals and ASG signals; at a fourth date subsequent to the third date, resetting the path.

Abstract: A device for measuring rotation including an NMR gyroscope having a sensing axis, a computer, a generating member configured to generate a magnetic field directed along the sensing axis, and a MEMS gyroscope rigidly connected to the NMR gyroscope, the MEMS gyroscope having a sensing axis aligned with the sensing axis of the NMR gyroscope, the MEMS gyroscope being suitable for delivering a MEMS signal representing a rotation about the sensing axis, the computer being configured to calculate, from an NMR signal output by the NMR gyroscope, information relating to a rotation about the sensing axis, and to analyse the MEMS signal over time in order to determine a current cut-off frequency, the computer also being configured to control the generating member in order to generate, over time, a magnetic field of which the amplitude is a function of the current cut-off frequency.

Abstract: The invention relates to a navigational aid method for an inertial navigation system including at least one inertial sensor (4) having a sensitive axis (X-X), each inertial sensor (4) comprising an ASG gyroscope (8) able to deliver an ASG signal representative of a rotation about the corresponding sensitive axis (X-X), and a MEMS gyroscope (10) able to deliver a MEMS signal representative of a rotation about the corresponding sensitive axis (X-X), the method including the steps of: between a first date and a subsequent third date, calculating a path from the MEMS signals; from the third date, calculating the path from the ASG signals; estimating a bias vector introduced by the MEMS gyroscopes (10), from the MEMS signals and ASG signals; at a fourth date subsequent to the third date, resetting the path.

Abstract: An inertial unit comprising an inertial core (3) that is connected to a control unit (50) and that includes three gyros (9, 10, 11) that are mounted relative to one another so as to have sensing axes (X, Y, Z) that are substantially perpendicular to one another, the gyros being vibrating axisymmetric gyros with hemispherical resonators, the unit being characterized in that the core is mounted on a carousel (2) arranged to drive the inertial core in rotation about an axis of rotation (4) at at least one frequency that corresponds to a minimum for spectral error density of the gyros. An angle-measurement method making use of the unit.

Abstract: An inertial unit comprising an inertial core (3) that is connected to a control unit. (50) and that includes three gyros (9, 10, 11) that are mounted relative to one another so as to have sensing axes (X, Y, Z) that are substantially perpendicular to one another, the gyros being vibrating axisymmetric gyros with hemispherical resonators, the unit being characterized in that the core is mounted on a carousel (2) arranged to drive the inertial core in rotation about an axis of rotation (4) at at least one frequency that corresponds to a minimum for spectral error density of the gyros. An angle-measurement method making use of the unit.

Abstract: A first strapdown navigation unit (2) generating a first state vector (X2u) whose components give position, attitude and speed values of a carrier with a small instantaneous error. The method includes actions consisting of: generating by means of a second navigation unit (1), a second state vector (X1u) whose components give position, attitude and speed values of the said carrier with a small long-term error; combining the first and second state vector to obtain an error observation vector (&dgr;Y); generating an error estimate vector ({circumflex over ( )}&dgr;X2u) from the error observation vector (&dgr;Y), by means of a filter (5); combining the error estimate vector ({circumflex over ( )}&dgr;X2u) thus obtained with the first state vector (X2u) so as to obtain an estimated vector ({circumflex over ( )}X2u) of the carrier position, attitude and speed values with a small instantaneous error and a small long-term error.

Abstract: Using an inertial master box mounted on a carrier for measuring its movements with respect to a geographic frame of reference of fixed directions along three axes Xg, Yg, Zg, a measuring method provides for continuously measuring an orientation of a frame of reference Xm, Ym, Zm tied to the inertial master box. Positioning is provided by applying a sequence of cycles of eight inversions of the inertial master box while keeping the axis Ym in a direction parallel to the axis Yg. A first motor causes a gimbal to pivot on a first axle secured to the carrier, while a second motor causes the inertial master box to pivot about a second perpendicular axle secured to the gimbal. A processor calculates three attitude angles by running a first inertial navigation program of the strapdown type and controls the first and second motors by running a second program.

Abstract: A first strapdown navigation unit (2) generating a first state vector (X2u) whose components give position, attitude and speed values of a carrier with a small instantaneous error.

Abstract: Using an inertial master box (3) mounted on a carrier for measuring its movements with respect to a geographic frame of reference of fixed directions along three axes Xg, Yg, Zg, the method comprises measuring actions which consist in constantly measuring an orientation of a frame of reference tied to the inertial master box Xm, Ym, Zm by using the inertial master box (3) in the geographic frame of reference, positioning actions which consist in applying a sequence of cycles of eight turnings-over of the inertial master box (3) each of which keeps the axis Ym in a direction parallel to the axis Yg, a succession of two turnings-over about the axis Xm being preceded and followed by a turning-over about the axis Zm, a succession of two turnings-over about the axis Zm being preceded and followed by a turning-over about the axis Xm.