RU1839886C - Method of setting sensitivity axis of pendulum accelerometer - Google Patents

Abstract

FIELD: instrument industry.

SUBSTANCE: method comprises measuring the component of the gravity force in two positions of the accelerometer. The given axis and axis of the maximum sensitivity of the accelerometer are set horizontally. The output signals of the accelerometer at two opposite directions of the axis of minimum sensitivity is measured, and the axis of maximum sensitivity is deflected by the angle defined as the half-difference of the values measured.

EFFECT: enhanced precision.

Description

The present invention relates to the field of instrumentation and can be used when adjusting the pendulum accelerometers (lateral stabilization) BS and AUD (automatic range control) when adjusting in gyroscopic platforms. The proposed method allows to increase the accuracy of the exposure axis of the sensitivity of the accelerometers relative to the program axis and to simplify the adjustment operation.

A known method of exhibiting the sensitivity axis of the accelerometer relative to the program axis, based on the measurement of accurately specified values of the component of the acceleration of gravity.

A known method of adjusting the position of the sensing element in a plane perpendicular to the direction of the pendulum is as follows:

1. The program axis perpendicular to the axis of the accelerometer suspension is set exactly to the horizon. In this case, the axis of the pendulum is in the horizon with the feedback turned on, the angle sensor - the torque sensor and the output signal of the accelerometer gives the value of the projection of gravity on the sensitivity axis of the accelerometer.

2. Using the adjusting device, the suspension axis of the pendulum accelerometer is tilted strictly in the vertical plane around the direction of the pendulum by the required angle, achieving the minimum value of the feedback current.

The minimum value of the feedback current is determined by the perpendicularity of the axis of rotation of the accelerometer of the program axis, the perpendicularity of the pendulum of the program axis, the angle of deviation of the axis of rotation of the accelerometer from the vertical and the moment of tension.

To estimate the error value of the sensitivity axis exhibition relative to the program axis, the previously obtained value of the self-weight current is used.

The disadvantages of this method are as follows:

1. The need to accurately expose the program axis to the horizon. The error of non-horizontalness is completely included in the error of adjustment.

2. The impossibility of taking into account the moment of tension of the moving system of the accelerometer and the increase in the error of the sensitivity axis exhibition relative to the program axis as a consequence of this.

3. The use of the measured value of the current of its own weight in assessing the error of adjustment.

4. Deformation of the device on which the accelerometer and program axis are mounted when tilted at angles of ± 60 °.

5. The impossibility of checking the position of the sensitivity axis in a fully assembled instrument - gyro platform due to the need for accurate angles.

The aim of the invention is to increase the accuracy of exhibiting the sensitivity axis relative to the program axis and simplifying the alignment process.

The objectives of the invention are realized by eliminating the exact definition of angles and excluding angles of inclination. Feedback current is measured at the horizontal position of the program axis with vertical positions of the accelerometer suspension axis differing by 180 °, and the accuracy of exposing the program axis to the horizon and the accelerometer turning around the program axis can be carried out with low accuracy - up to ± 30 angles. min

The essence of the invention will be clear from the description below.

The program axis perpendicular to the axis of rotation of the accelerometer pendulum and the direction of the pendulum with some initial error is roughly set to the horizon, the axis of rotation of the accelerometer pendulum perpendicular to the program axis is stopped by rotating the program axis vertically.

In this position of the accelerometer, a feedback current is measured. Then the accelerometer is turned so that the axis of rotation of the pendulum of the accelerometer is turned 180 ° relative to the first position, and the feedback current is measured. After taking measurements using the adjusting means, the axis of rotation of the pendulum of the accelerometer relative to the program axis is rotated by an angle determined by the half difference of measurements obtained in the first (0 °) and second (180 °) positions. To obtain the accuracy of exhibiting the sensitivity axis relative to the program axis of the order of 2 angles. sec it is enough to level the program axis with an accuracy of 15 angles. min and set the axis of rotation of the pendulum of the accelerometer with an accuracy of ~ 10 ang. min

We denote the angles of the considered scheme as follows:

φ ₁ is the angle between the axis of rotation of the pendulum of the accelerometer and the plane perpendicular to the program axis;

φ ₂ is the angle formed by the program axis with the horizon plane;

ψ ₁ is the angle formed by the axis of rotation of the pendulum of the accelerometer with a vertical plane passing through the program axis;

ψ ₂ is the angle of non-perpendicularity of the axis of the pendulum to the program axis.

Taking into account the accepted notation, it can be shown that the expression defining the difference in the absolute values of the feedback current at the positions 0 ° and 180 ° of the axis of rotation of the accelerometer pendulum relative to the program axis, up to the proportionality coefficient, has the form:

ΔI = i _{oc0 °} -i _{oc180 °} ≈k (2φ ₁ -2φ ₂ ² · φ ₁ -0.75φ ₁ ³ -ψ ₂ ² φ ₁ -2ψ ₁ ψ ₂ φ ₁ -ψ ₁ ² φ ₁ )

Given the smallness of φ ₂ , ψ ₁ , ψ ₂ we have:

Δi≈2φ ₁

When values of φ ₂ , ψ ₁ and ψ _{2 are of the} order of several angular minutes, their influence on the error of the sensitivity axis exhibition relative to the program axis due to the neglect of discarded terms does not exceed several angular seconds.

With this method, errors associated with the deformation of the alignment device during tilting are eliminated, since the tilts of the program axis themselves are absent. An exact exposition of the program axis relative to the horizon plane is not required, which greatly simplifies the alignment process. The proposed method can be used to check the position of the sensitivity axis relative to the program axis in the assembled devices (gyroplatforms), since accelerometers usually have the ability to rotate around program axes, for example, lateral stabilization system accelerometers.

The company conducted experimental studies that showed a fairly high stability of measurements of feedback current in the positions 0 ° and 180 °. This technique is used when adjusting prototypes of instruments.

Claims (1)

The method of exhibiting the axis of sensitivity of the accelerometer along a given axis of the coordinate system by measuring the component of gravity in its two positions, characterized in that in order to increase the accuracy of the exhibition, the specified axis of the coordinate system and the axis of maximum sensitivity of the accelerometer are set horizontally, the output signals of the accelerometer are measured in two opposite directions axis of minimum sensitivity and deflect the axis of maximum sensitivity in a vertical plane at an angle defined by half of the measurements values.