1. A system for determining parameters representing the orientation of a solid in movement, subject to a first vector field and a second vector field, said fields being of known directions in a fixed coordinate system not linked to the solid, said system comprising a first triaxial sensor and a second triaxial sensor, integral to said solid, for measuring the components of said respective vector fields along the axes of said sensors, and means for determining the rotation matrix of the solid, characterized in that said means for determining said rotation matrix comprise: correction means, which can be deactivated on command, suitable for correcting the influence exerted on the measurements of at least one of said sensors by an additional vector field of the same nature as said measured vector field, and delivering at least one corrected vector; and first means for calculating a third vector suitable for calculating said third vector which is not coplanar to the plane formed by the two vectors delivered by said correction mean, and such that the angles of the axis system formed by the third vector and the two vectors delivered by said correction means remain constant.