Planar structure for a triaxial gyrometer

An inertial sensor able to measure information relating to rotation in three (X, Y, Z) orthogonal axes, said inertial sensor comprising:

• a support and a sensitive element secured to the support;
• said sensitive element being adapted to vibrate relative to the support in a primary vibration mode when it is excited by an excitation device, and in secondary vibration modes induced by a Coriolis force, when the inertial sensor is moved about an axis and the sensitive element is excited by an excitation device;
• said sensitive element comprising a deformable frame which extends in a plane (X-Y) and at least two deformable projections which extend in the same plane (X-Y);
• said primary vibration mode implementing a deformation of the deformable frame;
• said secondary vibration modes implementing in-plane or out-of-plane bending deformations of said at least two deformable projections wherein:
• each of said at least two deformable projections is a beam of a substantially square cross-section whose longitudinal axis is rectilinear;
• each of said beams being connected only by one of its ends to the deformable frame at a location at which the amplitude of the primary vibration mode is at a maximum so that in the primary vibration mode, each of said beams is translated on its longitudinal axis;
• the inertial sensor extends in one and the same plane;
• the deformable frame and said at least two deformable projections possess a plane of symmetry parallel to the (X-Y) plane, due to which the translation of said at least two deformable projections occurs without deformation or stress;
• the longitudinal axes of said at least two deformable projections, along which the latter are displaced by the primary vibration, are non-collinear;
• and the inertial sensor further comprises a device for detecting each of the secondary vibration modes;
• said detection device exploiting an effect caused by the deformation of said beams.