System and method for testing near-ground velocity scale factor error of fiber-optic gyroscope

Abstract

The invention belongs to the technical field of fiber-optic gyroscope precision control, and particularly relates to a fiber-optic gyroscope near-to-ground velocity scale factor error test system and method, and the method comprises the following steps: vertically placing a fiber-optic gyroscope sensitive shaft on a rotating frame; adjusting the rotating frame, and recording the initial output of the fiber-optic gyroscope; the motor is driven to step by 10 degrees through the angle encoder every time, and each step angle data is recorded; then returning to the initial position, rotating by 180 degrees, and recording data of each stepping angle; calculating the decomposed earth rotating speed of each stepping angle, wherein the decomposed earth rotating speed is the sensitive rotating speed of the fiber-optic gyroscope; calculating the scale factor of each stepping angle through the sensitive rotating speed of the fiber-optic gyroscope; and performing least square fitting on the values, wherein the slope of a straight line after fitting is the near-to-ground velocity scale factor of the fiber-optic gyroscope. The invention ensures that forward and reverse rotating speeds are opposite numbers through the rotating mechanism, and realizes accurate measurement of scale factor errors under the condition of low rotating speeds such as near-ground speed and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of fiber optic gyroscope precision control, and in particular relates to a fiber optic gyroscope near-ground speed scaling factor error testing system and method. Background Art

[0002] With the widespread application of fiber optic gyroscopes, the accuracy requirements of fiber optic gyroscopes are increasing day by day. In particular, some high-reliability and high-precision applications have increasingly stringent requirements on scale factor indicators. Therefore, it is particularly important to accurately analyze and measure the asymmetry of the scale factor.

[0003] The asymmetric error of the scale factor is a sign that when the fiber optic gyro inputs a large reverse rotation speed, there is a numerical error in the output scale. For the rotating inertial navigation system, the above error accumulates over time and eventually affects the positioning accuracy of the system. The analysis of the asymmetry of the scale factor is as follows: In the formula, is the scale factor asymmetry, represents the positive speed scaling factor, Represents the reverse speed scale factor. Typically, this error is tested by applying a reverse speed through a rate stage and calculating the scale asymmetry from the FOG output.

[0004] , where D is the digital value output by the fiber optic gyroscope, is the actual speed output by the turntable. is the digital value of the forward speed output of the fiber optic gyroscope, It is the digital value of the reverse speed output of the fiber optic gyroscope. is the actual speed of the turntable forward output, It is the actual speed of the turntable reverse speed output.

[0005] When the forward and reverse speeds of the turntable are absolutely accurate and opposite to each other, At this time, the fiber optic gyroscope outputs the real scale asymmetry, but due to the mechanical control deficiencies in the turntable reversing process, there is inevitably a certain error in the size of the forward and reverse speeds. At this time, the asymmetric error of the turntable speed will affect the scale error of the fiber optic gyroscope. Assume that the output size of the fiber optic gyroscope is equal and the direction is opposite when the forward and reverse speeds are =- , then the fiber optic gyro scale factor error is 0, assuming But after the transfer, , Therefore, the above asymmetric error is the asymmetric error of the rotation speed of the turntable. The above error is actually the error of the test system, and it is difficult to eliminate it fundamentally even if the control accuracy of the turntable is improved.

[0006] To this end, the present invention proposes a scale factor asymmetry method that is independent of the turntable rotation speed. This method changes the direction of the signal light beam in the fiber optic gyroscope by a photoelectric method to achieve the commutation of the fiber optic gyroscope rotation speed without changing the turntable rotation direction, thereby reducing the asymmetry error of the turntable's positive and negative rotation speeds. Summary of the invention

[0007] The present invention aims to solve at least one of the technical problems existing in the related art. To this end, the present invention provides a scale factor asymmetry method that is independent of the rotation speed of a turntable, which changes the direction of a signal light beam in a fiber optic gyroscope by an optoelectronic method to achieve the reversal of the rotation speed of the fiber optic gyroscope without changing the rotation direction of the turntable, thereby realizing a fiber optic gyroscope near-ground speed scale factor error test system and method that reduces the asymmetry error of the forward and reverse rotation speeds of the turntable.

[0008] A method for testing a ground speed scale factor error of a fiber optic gyroscope comprises the following steps: S1. Place the sensitive axis of the fiber optic gyroscope vertically on the rotating frame; S2. Adjust the rotating frame and record the initial output of the fiber optic gyroscope: The east-finding method is used to ensure that the sensitive axis of the fiber optic gyroscope points to the east. The position pointing to the east is taken as the initial position. The initial value of the angle encoder is zero. The output F0 of the fiber optic gyroscope is recorded at this position. Then the motor drives the rotating frame to rotate 180° and then stop. The output F of the fiber optic gyroscope is recorded. 0- ; S3. Each time the angle encoder drives the motor to step 10°, and records each step angle data F i ; Then return to the initial position, rotate 180 degrees and record each step angle data F i- , where i=0,1,2....9; S4. Calculate the decomposition of the earth speed for each step angle, where the decomposition of the earth speed is the fiber optic gyro sensitive speed V i ; S5. Sensing rotation speed V through fiber optic gyro i Calculate the scale factor K for each step angle i ; S6. Through K i The value of is fitted by the least square method, and the slope K of the fitted straight line is the fiber optic gyro ground speed scaling factor.

[0009] Furthermore, the method for calculating the earth speed decomposed by each step angle in step S4 is: According to the local latitude Ф value, ground speed Ωe =15° / h; Fiber optic gyro sensitive speed V i Expressed as V i =Ω e •sin(Ф+i•10).

[0010] Furthermore, in step S5, the scaling factor K of each step angle is i Expressed as K i =(F i -F i- ) / (2•V i ).

[0011] A fiber optic gyroscope ground speed scale factor error test system, which executes the fiber optic gyroscope ground speed scale factor error test method. It includes a frame driving device for fixing the fiber optic gyroscope and an angle encoder for driving the frame driving device. The frame driving device includes a rotating frame, a frame driving shaft connected to the rotating frame, and a driving motor for driving the frame driving shaft. The fiber optic gyroscope is vertically fixed on the rotating frame, and the angle encoder drives the driving motor to rotate.

[0012] Furthermore, the sensitive axis of the fiber optic gyroscope is perpendicular to the ground normal of the rotating frame.

[0013] Furthermore, the frame drive shaft is supported by bearings on both sides of the relatively rotating frame.

[0014] Furthermore, the angle accuracy of the angle encoder is 1 arc second.

[0015] Furthermore, the rotation angle Φ of the angle encoder and the rotation angle Φ+180° are positioned by positioning pins to ensure repeatability.

[0016] The above one or more technical solutions in the embodiments of the present invention have at least one of the following technical effects: The present invention does not use a turntable as the input speed, but proposes to use the ground speed decomposition method to obtain the input speed, and ensures that the forward and reverse speeds are opposite to each other through a rotating mechanism, which can effectively overcome the hysteresis of the traditional rate turntable, especially the defect of large error of the turntable at low speed. Accurately measure the scale factor error at low speeds such as near ground speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 It is a schematic diagram of the sensitive ground speed process of the fiber optic gyroscope provided in the embodiment of the present invention.

[0019] Figure 2 It is a schematic diagram of precise rotation control of the sensitive axis of the fiber optic gyroscope provided in an embodiment of the present invention.

[0020] In the figure: 1. Fiber optic gyroscope, 2. Rotating frame, 3. Frame drive shaft, 4. Bearing support, 5. Drive motor, 6. Angle encoder, 7. Frame drive device, 8. Earth axis, 9. Earth. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention. The following embodiments are used to illustrate the present invention, but cannot be used to limit the scope of the present invention.

[0022] In the description of the embodiments of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limitations on the embodiments of the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0023] In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0024] In the embodiments of the present invention, unless otherwise clearly specified and limited, the first feature being "above" or "below" the second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0025] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0026] Combine the following Figure 1-Figure 2 The present invention describes a fiber optic gyroscope near-ground speed scale factor error testing system and method.

[0027] The fiber optic gyroscope near-ground speed scale factor error test system includes a frame drive device 7 for fixing the fiber optic gyroscope 1 and an angle encoder 6 for driving the frame drive device. The frame drive device includes a rotating frame 2, a frame drive shaft 3 connected to the rotating frame, and a drive motor 5 for driving the frame drive shaft. The fiber optic gyroscope is vertically fixed on the rotating frame, and the angle encoder drives the drive motor to rotate.

[0028] The fiber optic gyroscope 1 is fixed on the rotating frame 2 to ensure that the sensitive axis is perpendicular to the frame ground normal. The driving motor 5 drives the rotating frame 2 to rotate through the frame driving shaft 3. The above connections are all good rigid connections without distortion angles. The rotating frame 2 and the bearing support 4 are well rigidly connected without bending deformation. The motor drive angle can be accurately controlled by the angle encoder 6, and the angle accuracy is 1 arc second. In particular, the two positions of the rotation angle Φ and the rotation Φ+180° have positioning pins to ensure high repeatability, and the angle error is better than 1 arc second.

[0029] Combination Figure 1 and Figure 2 The measurement process of precise rotation control of the sensitive axis of the fiber optic gyroscope is to place the sensitive axis of the fiber optic gyroscope 1 vertically on the rotating frame 2 to ensure good contact and rigid connection. Adjust the rotating frame, record the output of the fiber optic gyroscope, and combine the earth's axis 8 with the earth's 9 to ensure that the sensitive axis of the fiber optic gyroscope points to the east through the east-finding method. This position is used as the initial position, and the initial value of the angle encoder is zero degrees. Record the output F0 of the fiber optic gyroscope at this position. Then the motor drives the rotating frame to rotate 180° and then stop, and record the output F of the fiber optic gyroscope. 0- . Each time the angle encoder drives the motor to step 10°, the data F is recorded i At this time, the F9 fiber optic gyro sensitive axis points to the north. Then return to the initial position, rotate 180 degrees and record data F i- Then according to the local latitude Φ value, ground speed Ω e =15° / h. Calculate the earth speed for each step angle, and the decomposed earth speed is the fiber optic gyro sensitive speed V i , V i =Ω e •sin(Ф+i•10), where i=0,1,2....9. The scaling factor of each step angle is K i =(F i -F i- ) / (2•V i ); by K i The value of is fitted by the least square method, and the slope K of the fitted straight line is the fiber optic gyro ground speed scaling factor.

[0030] The present invention does not use a turntable as the input speed, but proposes to use the ground speed decomposition method to obtain the input speed, and ensures that the forward and reverse speeds are opposite to each other through a rotating mechanism, which can effectively overcome the hysteresis of the traditional rate turntable, especially the defect of large error of the turntable at low speed. Accurately measure the scale factor error at low speeds such as near ground speed.

[0031] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for testing the ground speed scale factor error of a fiber optic gyroscope, characterized in that: The steps include: S1. Place the sensitive axis of the fiber optic gyroscope vertically on the rotating frame; S2. Adjust the rotating frame and record the initial output of the fiber optic gyroscope: The east-finding method is used to ensure that the sensitive axis of the fiber optic gyroscope points to the east. The position pointing to the east is taken as the initial position. The initial value of the angle encoder is zero. The output F0 of the fiber optic gyroscope is recorded at this position. Then the motor drives the rotating frame to rotate 180° and then stop. The output F of the fiber optic gyroscope is recorded. 0- ; S3. Each time the angle encoder drives the motor to step 10°, and records each step angle data F i ; Then return to the initial position, rotate 180 degrees and record each step angle data F i- , where i=0,1,2....9; S4. Calculate the decomposition of the earth speed for each step angle, where the decomposition of the earth speed is the fiber optic gyro sensitive speed V i ; S5. Sensing rotation speed V through fiber optic gyro i Calculate the scale factor K for each step angle i ; S6. Through K i The value of is fitted by the least square method, and the slope K of the fitted straight line is the fiber optic gyro ground speed scaling factor.

2. A method for testing near-ground speed scaling factor error of a fiber optic gyroscope according to claim 1, characterized in that: The method for calculating the earth speed resolution for each step angle in step S4 is: According to the local latitude Ф value, ground speed Ω e =15° / h; Fiber optic gyro sensitive speed V i Expressed as V i =Oh e ·sin(Φ+i•10).

3. A method for testing near-ground speed scaling factor error of an optical fiber gyroscope according to claim 1, characterized in that: In step S5, the scale factor K of each step angle i Expressed as K i =(F i -F i- ) / (2•V i )。 4. A fiber optic gyroscope ground speed scale factor error test system, which implements the fiber optic gyroscope ground speed scale factor error test method described in any one of claims 1 to 3, characterized in that: It includes a frame driving device for fixing the fiber optic gyroscope and an angle encoder for driving the frame driving device. The frame driving device includes a rotating frame, a frame driving shaft connected to the rotating frame, and a driving motor for driving the frame driving shaft. The fiber optic gyroscope is vertically fixed on the rotating frame, and the angle encoder drives the driving motor to rotate.

5. The fiber optic gyro near ground speed scale factor error test system according to claim 4, characterized in that: The sensitive axis of the fiber optic gyroscope is perpendicular to the ground normal of the rotating frame.

6. The fiber optic gyro near ground speed scale factor error test system according to claim 4, characterized in that: The frame drive shaft is supported by bearings on both sides of the relatively rotating frame.

7. A fiber optic gyroscope near ground speed scale factor error test system according to any one of claims 4 to 6, characterized in that: The angle encoder has an angular accuracy of 1 arc second.

8. A fiber optic gyroscope near ground speed scale factor error test system according to any one of claims 4 to 6, characterized in that: The rotation angle Φ and the rotation Φ+180° positions of the angle encoder are ensured to have repeatability by means of positioning pins.

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