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Innalabs, Inc.

Alain Renault

Jose Beitia

Isaak M Okon

Alain Jeanroy

Jean-Michel Caron

Vincent Ragot

Paul Vandebeuque

Alain Giani

Pierre Loisel

Jérôme Dido

Christian Lignon

Christopher Fell

Dmitri V Simonenko

Paul Featonby

Johann Courteaud

André Boyer

Bernard Varusio

Philippe Combette

Etienne Brunstein

Isaak Markovich Okon

Nicolas Crespy

Alain Boyer

The invention relates to an inertial navigation system for a carrier comprising a core comprising gyroscopic sensors making it possible to determine the angular velocity thereof according to three axes defining a reference trihedron, two of the axes defining a reference plane and the third axis being at right angles to this plane. The device comprises command and control means making it possible to rotate the core about the third axis and to determine the direction of the geographic north on the basis of the information supplied by the gyroscopic sensors and by an accelerometer placed in the reference plane; the rotation of the core being performed with a period for which the value of the Allan variance of the stability error of the gyroscopic sensors is lower than a given value guaranteeing the accuracy with which the direction of the geographic north can be known.

Inertial navigation system with improved accuracy

A gyroscope comprising a resonant structure and a plurality of transducers configured to drive a vibrational mode in the resonant structure and detect vibrations of the resonant structure, wherein at least one of the plurality of transducers comprises a piezoelectric mono crystal.

Gyroscope with piezoelectric monocrystal transducers

The present invention is concerned with a method of calibrating a vibrating gyroscope. The method comprises exciting a vibration along an excitation axis of a resonant structure wherein the excitation axis is positioned at a first angular position, sensing the vibration of the resonant structure on a first sensing axis of the resonant structure while the excitation axis is positioned at the first angular position, generating a first sensing signal indicative of the sensed vibration of the resonant structure on the first sensing axis, rotating the excitation axis in a continuous manner around the resonant structure to a second angular position, sensing the vibration of the resonant structure on a second sensing axis of the resonant structure while the excitation axis is positioned at the second angular position, generating a second sensing signal indicative of the sensed vibration of the resonant structure on the second sensing axis and adding the first sensing signal to the second sensing signal in order to derive a bias of the gyroscope.

Method for calibrating vibratory gyroscope

The invention relates to gyroscopic instruments. The method for calibrating the scale factor of an angular velocity sensor or an axisymmetric vibratory gyroscope, which method uses a control amplitude signal, a control precessional signal CP and a control quadrature signal CQ for exciting the vibration of a resonator on a resonant frequency, involves a first step of pre-calibration which consists of measuring and recording an initial scale factor and the value of an initial control signal, and a second step of measuring the value of the current control signal and establishing a scale factor SF that is corrected on the basis of a proportional relationship involving the initial scale factor SF&#xb0;, the initial value of the control signal Y&#xb0; and the current value of the control signal Y&#xb0; according to the formula SF=SF&#xb0;Y/Y&#xb0;.

Calibration method for the scale factor of an axisymmetric vibratory gyroscope or gyrometer

An inertial unit comprising an inertial core () that is connected to a control unit () and that includes three gyros () that are mounted relative to one another so as to have sensing axes (X, Y, Z) that are substantially perpendicular to one another, the gyros being vibrating axisymmetric gyros with hemispherical resonators, the unit being characterized in that the core is mounted on a carousel () arranged to drive the inertial core in rotation about an axis of rotation () at at least one frequency that corresponds to a minimum for spectral error density of the gyros. An angle-measurement method making use of the unit.

Inertial unit having vibrating gyros mounted on a carousel, and an angle-measurement method

An effective and precise method and system for compensation and measurement of a zero-bias in an axisymmetrical CVG (Coriolis Vibrating Gyroscope) is provided. Principal mode is driven according to an X-axis. Angular velocity is measured through Coriolis mode excitation along Y-axis. The sensitive axis of the gyroscope is reversed by 180 degrees by switching input and sense signals. Vibration is then driven along Y-axis and angular velocity is sensed along X-axis. On each position, after an arbitrary period of time, the gyroscope output is stored. Half-difference in outputs between two opposite position gives angular velocity and zero-bias effect is canceled. Half-sum in outputs between two opposite position gives the zero-bias error.

Force-rebalance coriolis vibratory gyroscope

The method of calibrating a scale factor of an axially-symmetrical vibrating rate gyro operating by applying an amplitude control signal (CA) and a precession control signal (CP) to a vibrator member () set into vibration at a given frequency comprises a pre-calibration step consisting in calculating a reference gain ratio between a drive gain (Gmx) in a first direction and a drive gain (Gmy) in a second direction in modal quadrature with the first direction, and in storing the reference gain ratio, and a calibration step consisting in calculating a value for a measurable magnitude associated with the scale factor by a proportionality relationship including the reference gain ratio, and calculating a corrected scale factor on the basis of the value of the measurable magnitude and the stored reference gain ratio.

Method for calibrating a scale factor in an axisymmetrical vibrating gyrometer

The acceleration measurement system has a first thermal cell optimized in sensitivity and a second thermal cell optimized in passband, which cells are connected to inputs of a servo-control loop including an amplifier presenting gain that varies as a function of input signal frequency.

Thermal cell system for measuring acceleration

A thermal accelerometer comprising two detector strands having resistivity that is temperature sensitive, a detector member for detecting a temperature difference between the detector strands, a feedback member for establishing temperature equilibrium between the detector strands by supplying the detector strands with pulse feedback signals of variable width, a member for calculating acceleration, and a multiplexer member connected to the detector strands, to the detector member, and to the feedback member so as to perform the following in alternation: measuring the temperature difference between the detector strands; and providing the detector strands with the feedback signals, the widths of the pulse signals being determined by comparing a sawtooth signal with DC signals representative of the temperature difference between the detector strands.

Thermal accelerometer with automatic zero control

The method serves to compensates anisotropy in an inertial rotation sensor comprising a metallized vibrating bell () having a bias voltage applied thereto, the vibrating bell () having an edge () electrodes (), and the method comprises the steps of measuring, preferably by multiplexing, the anisotropy between the electrodes and of applying to the electrodes a fraction of the bias voltage that depends on the differences measured between the electrodes.

Method of compensating anisotropy in a vibrating-bell inertial rotation sensor

In an implementation in rate gyro mode, the method includes exciting the vibrating member with a combination of control signals including an amplitude control signal at a frequency twice the resonant frequency, and a quadrature control signal at DC. In free gyro mode, the method includes the steps of applying a combination of signals to common electrodesand of applying the combination in alternation to main electrodesandand to auxiliary electrodesandinterleaved between the main electrodes.

Method for implementing a resonator under electrostatic forces

The thermal accelerometer of the invention comprises an enclosure having disposed therein a central filament powered by alternating electric current of zero mean amplitude and having a frequency lying between first and second resonant modes of vibration of the central filament, the central filament lying between detector filaments adjacent to reaction filaments powered by alternating electric current of zero mean amplitude and having a frequency lying between the first and second resonant modes of vibration of the reaction filaments.

Thermal accelerometer with reduced sensitivity to external magnetic fields

The inertial rotation sensor comprising a vibrating resonator associated with transducers defining a pair of control channels and a pair of detection channels, preferably comprises a single multiplexer member for all of the channels, the multiplexer member being associated with a processing unit generating cycles comprising control action times on each control channel followed by detection action times on each detection channel, with two succession action times being separated by a relaxation time.

Vibrating resonator inertial rotation sensor

In an implementation in rate gyro mode, the method comprises the steps of exciting the vibrating member by means of a combination of control signals comprising an amplitude control signal at the resonant frequency of the vibrating member or at a frequency twice the resonant frequency, a precession control signal at a frequency twice the resonant frequency, and a quadrature control signal at DC, at the resonant frequency, or at a frequency twice the resonant frequency. In free gyro mode, the method includes the steps of applying a combination of signals to common electrodesand of applying said combination in alternation to main electrodesandand to secondary electrodesandinterleaved between the main electrodes.

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Pontoise, France

Alain Renault