US 12,332,080 B2
Method for calibrating the difference in stiffness and/or quadrature of a vibrating inertial sensor
Nicolas Vercier, Valence (FR); and Nicolas Martin, Valence (FR)
Assigned to THALES, Courbevoie (FR)
Appl. No. 18/029,890
Filed by THALES, Courbevoie (FR)
PCT Filed Oct. 8, 2021, PCT No. PCT/EP2021/077960
§ 371(c)(1), (2) Date Mar. 31, 2023,
PCT Pub. No. WO2022/078917, PCT Pub. Date Apr. 21, 2022.
Claims priority of application No. 2010492 (FR), filed on Oct. 14, 2020.
Prior Publication US 2023/0366701 A1, Nov. 16, 2023
Int. Cl. G01C 25/00 (2006.01); G01C 19/574 (2012.01)
CPC G01C 25/005 (2013.01) [G01C 19/574 (2013.01)] 11 Claims
OG exemplary drawing
 
1. A method for calibrating a stiffness mismatch ΔK and/or a quadrature Kxy of a vibrating inertial angular sensor, the inertial sensor comprising a resonator (Res) extending about two mutually perpendicular axes x and y defining a sensor frame xy and comprising:
at least one vibrating proof mass (M1), said at least one proof mass comprising at least two parts configured to vibrate in phase opposition with respect to each other at a vibration angular frequency (ω) and in a direction x′ defining a wave frame x′y′, a vibration wave (OV) along x′ making an electrical angle (θ) to the axis x;
a plurality of electrostatic transducers controlled by electrical voltages and operating along the two axes x or y, including at least:
a pair of detection transducers (Dx, Dy) configured to detect the movements of the vibration wave along the axis x and the axis y;
a pair of excitation transducers (Ex, Ey) to which excitation forces are applied along the axis x and the axis y, respectively, via a plurality of excitation commands determined by servos on the basis of the detected movements, these being configured to maintain the wave at a constant amplitude via an amplitude command (Ca) and, where appropriate, to rotate said vibration wave via a precession command (Cp) and a command (Cq) for controlling the quadrature of the wave;
a pair of quadrature compensation transducers (Q+, Q−), controlled via a quadrature command (CTq); and
a pair of stiffness adjustment transducers (Tx, Ty), controlled via a stiffness command (CTx) setting stiffness along the axis x and a stiffness command (CTy) setting stiffness along the axis y, respectively, forming a stiffness command (CTf);
the resonator (Res) having a stiffness matrix KC in the sensor frame and a stiffness matrix KO in the wave frame;
the calibrating method being applied when the inertial sensor is in operation with a vibration wave (OV) vibrating in the direction x′;
the calibrating method comprising the steps of:
A determining an electrical angle (θk, θ(t));
B recovering at least one term of the stiffness matrix KO in the wave frame x′y′, which may be a quadrature term KO (2,1) or a stiffness term KO (1,1), said term taking the form of a sum of functions in cos(iθ) and sin(iθ), i being an integer varying between 1 and n, n being greater than or equal to 1;
steps A and B being reiterated either for a plurality of electrical angles (θk), where k is an integer varying between 1 and m, m being greater than or equal to 2, or for a duration (T) during which the vibration wave (OV) rotates continuously through an electrical angle (θ(t)) varying as a function of time (t); then
C determining amplitudes of the functions in cos(iθ) and sin(iθ); and
D determining the stiffness mismatch ΔK and the quadrature Kxy,
respectively, on the basis of the determined amplitudes.