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Safran Electronics & Defense

Jean-Michel Caron

Alain Renault

Alain Jeanroy

Vincent Ragot

David Roberfroid

The method of aligning an inertial unit having an axially symmetrical vibrating sensor that generates vibration comprises the step of establishing the vibration in a position for which the sensor presents variation in drift error that is the smallest relative to variation in drift error for other positions of the vibration.

Method of aligning an axisymmetric vibrating sensor inertial navigation system and corresponding inertial navigation system

A method of correcting the gain of a capacitive member having electrodes that are movable relative to each other including the steps of successively applying to one of the electrodes, reduced bias voltages having opposite signs and a common value below a threshold for which a remanent field generated by said reduced bias voltages can be measured, making corresponding measurements of the output signals from the capacitive member; taking an average, and correcting the gain of the capacitive member as a function of the measured output signal.

Method of correcting the gain of a capacitive member, and a device for implementing the method

In a gyroscopic system comprising at least four vibratory gyroscopes, a first measurement is provided by said vibratory gyroscope to be calibrated, and a second measurement is provided by a combination of the measurements from the other vibratory gyroscopes of the system. At the level of the vibratory gyroscope to be calibrated, an initial command is applied in order to command a change in position from a first vibration position (&#x3b8;) to a second vibration position (&#x3b8;). A calibrated scale factor value of the vibratory gyroscope to be calibrated is then determined on the basis of a calculated value in relation to the change in position, based on the period of time during which the initial command is applied, the initial command, an angular difference between the first and second vibration positions measured according to the first measurement and an angular difference between the first and second vibration positions measured according to the second measurement.

Calibration of gyroscopic systems with vibratory gyroscopes

A gyroscopic system comprises at least four vibratory gyroscopes capable of changing vibration position. A first measurement is provided by a gyroscope to be calibrated and a second measurement is provided by a combination of the respective measurements from the other gyroscopes of the system, these first and second measurements being carried out along the same measurement axis. The determination () of a measurement drift value between the first measurement and the second measurement is followed by a command () to change the vibration position of the gyroscope to be calibrated to another vibration position and a drift value is again determined. The vibration position change command and the determination of a drift value are repeated () K times, K being a positive integer. Then, a drift model is generated () as a function of the vibration position of the gyroscope to be calibrated on the basis of the drift values obtained.

Calibration of 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

A method and device of determining a speed of rotation of an axially symmetrical vibrating sensor. The sensor has a vibrating member associated with control electrodes and with detection electrodes for generating a vibration presenting an elastic line possessing periodicity of order n and having a position that is variable as a function of the rotation of the sensor. The method includes performing successive evaluations of the speed for a predetermined number of positions of the vibration relative to the electrodes. The positions are geometrically offset relative to each other and the vibration is moved from one position to another by applying a precession command using a pre-established scale factor. The method also includes determining a speed of rotation in function of the evaluations.

Method of determining a speed of rotation of an axially symmetrical vibrating sensor, and a corresponding inertial device

The method of determining the speed of rotation of an axially symmetrical vibrating sensor of order. The method includes: performing a first evaluation of the speed of rotation while a vibration generated by the vibrating sensor lies in a first position relative to electrodes generating the vibration; applying a precession command so that the vibration comes successively into positions that are offset by 45&#xb0;, 90&#xb0;, and 135&#xb0; relative to the first position; performing evaluations of the speed of rotation while the vibration lies in the offset positions; and taking a mean of the evaluations of the speed of rotation in the various positions of the vibration.

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.

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Saint-Gratien, France

Jean-Michel Caron