Safran Electronics & Defense

Sagem Defense Securite

Yves Becheret

David Roberfroid

Michel Destelle

Jean-Luc Demange

A method of detecting an operation to spoof a first positioning device carried by a first vehicle moving in a zone in which at least one second vehicle carrying a second positioning device is also moving, the method comprising the step of causing at least one first positioning value to be calculated for each vehicle from initial satellite signals received by each device; the method being characterized in that it further comprises the steps of: causing the second device to initiate a latching stage in order to make a new search for satellite signals and using the new satellite signals received by the second device to calculate a second positioning value for the second vehicle at the same instant as the first value; comparing the first and second values relating to the second vehicle; and issuing a warning when the two values do not coincide.

Method and device for detecting a decoy operation of a GNSS system

A method of navigating a vehicle (A) by means of a navigation algorithm arranged to determine spatial information (p(xr, yr, zr), v, a(&#x398;xr, &#x398;yr, &#x398;zr), PL) on the basis firstly of inertial measurements (Mi) coming from a signal processor circuit () for processing the signals from an inertial measurement unit (I) and secondly of pseudo-distance measurements (Mpd) determined in response to receiving signals from positioning satellites, the measurement processor circuit () having a calibration input adjustable on a self-calibration value (VCal) in order to reduce the influence of an error of the inertial measurement unit (I) on the spatial information (p(xr, yr, zr), v, a(&#x398;xr, &#x398;yr, &#x398;zr), PL) supplied by the navigation algorithm. The navigation algorithm makes use of at least: a Kalman-Schmidt filter () arranged to detect faulty measurements among the measurements and to prevent them from being used in determining the spatial information (p(xr, yr, zr), v, a(&#x398;xr, &#x398;yr, &#x398;zr), PL), a Kalman filter () that is set to supply at least one estimate (E) of at least one error affecting the inertial measurement unit (I) and covariance (Cov) associated with said estimate, and a consolidation algorithm () programmed to compare the covariance with a first covariance threshold and to store the estimate if the covariance is less than the first covariance threshold in order to update the self-calibration value by means of the estimate of the error of the inertial measurement unit.

Doubly filtered navigation method

The invention concerns a method for controlling the integrity of the value of a piece of navigation information delivered by a merging/consolidation device including a plurality of processing modules. Each module generates a navigation solution from measurements coming from one or a plurality of separate navigation devices, which involves defining, for each processing module, a radius of protection, corresponding to a given probability of failure. The method includes defining at least one consolidated area that encompasses protection areas centered on the solution values that are output from the processing modules and that correspond to the radii of protection defined for these modules. The radius of protection of the merging/consolidation device for the probability of failure itself is defined to correspond to the consolidated area.

Integrity control method and merging/consolidation device comprising a plurality of processing modules

A method of calibrating an inertial unit is provided. During a first static stage, in which the inertial unit is in a first orientation, measurements are taken by means of the accelerometers and the inertial rotation sensors. During a dynamic stage, the orientation of the inertial unit is changed, at least in part in azimuth, from the first orientation towards a second orientation, while taking measurements by means of the inertial rotation sensors. During a second static stage, in which the inertial unit is in the second position, measurements are taken by means of the accelerometers and of the inertial rotation sensors. For each static stage, a direction, an amplitude, and a mean speed of rotation for apparent gravity in an inertial frame of reference is estimated, variation is calculated in orientation between the static stages, and the accelerometer biases is deduced therefrom.

Method of calibrating an inertial assembly comprising a dynamic phase between two static phases

The invention relates to an orientation device comprising: a true north finder including a rate-gyroscope-type member, as well as sensors that can be used to measure the inclination of the device in relation to the horizontal, and associated calculation means for determining the orientation of the true north used on information provided by the rate gyroscope-type member and the sensors. According to the invention, the device also includes three feet that are used to support the device when it is placed on a support, at least one of said feet including a built-in sensor that changes state when the device is resting on a support by means of the feet, and means for automatically triggering the determination of the orientation of the north when the device is sufficiently horizontal and when the sensor indicates that it is placed on a support.

Orientation device including means for detecting that the device is lying flat on a support

A method of determining a heading in the geographical North direction by means of an inertial sensor module having three rate gyro measurement axes and three accelerometer measurement axes, the method comprising the steps of:

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Boulogne-Billancourt, France

Yves Becheret