Hybrid ahrs system comprising a device for measuring the integrity of the calculated attitude

A system for measuring the attitude of a carrier, said system being hybridized and comprising at least:

• a satellite positioning system;
• a measurement unit comprising three gyrometers and three accelerometers;
• electronics for computing attitude information of the carrier from information obtained from the satellite positioning system and from the measurement unit,
• wherein the computation electronics comprise a means for computing an angular protection radius, that is to say an angular radius such that the risk of the error between the calculated attitude and the true attitude of the carrier not lying within this radius is less than a given probability, said radius being equal to the sum of two contributions, the first contribution being equal to the attitude errors linked to the measurement unit, the second contribution being equal to the errors induced on the attitude estimations by the position errors due to the satellite positioning system, taking into account an assumed failure of the satellite positioning system, said satellite positioning system guaranteeing that, subject to a given probability of failure, the error on the position is below an integrity radius, above this integrity radius, the satellite positioning system being declared as failed.