A calibration method for ring laser gyroscopes based on the zero position signal of a circular grating encoder

Abstract

The present invention discloses a calibration method for a ring laser gyro based on the zero position signal of a circular grating encoder, which relates to the field of measurement and control technology and instruments. By establishing a measurement model of the ring laser gyro; using the measurement data of the ring laser gyro and the zero position signal of the circular grating encoder collected respectively when the turntable is stationary and when the turntable rotates uniformly forward and backward, the offset coefficient, scale factor and angular increment value of the measurement model of the ring laser gyro are calibrated. Based on the zero position signal of the circular grating encoder and the principle of circumferential closure, the scale factor in the measurement model of the ring laser gyro is calibrated, thereby calibrating the ring laser gyro. The present invention can be applied to the precise measurement and calibration of the dynamic motion parameters of the turntable.

Description

Technical Field

[0001] The present invention relates to the field of measurement and control technology and instruments, and particularly to a calibration method for a ring laser gyroscope based on the zero position signal of a circular grating encoder. Background Art

[0002] A turntable is a rotating platform whose rotation parameters can change according to specific rules and has high stability. The turntable is applied to the calibration of the angular displacement, angular velocity, angular acceleration, and dynamic characteristics of inertial devices, tests the performance of the inertial navigation system, and gives a quantitative evaluation. Therefore, to further improve the motion accuracy of the turntable and its calibration accuracy for inertial devices, higher accuracy requirements are put forward for the calibration method of inertial technology test equipment.

[0003] The ring laser gyroscope (RLG) is widely used in the measurement of angular motion parameters of a turntable. It has high resolution and relatively mature installation and positioning technology. When applied to the calibration of a turntable, it can be flexibly and conveniently installed on the turntable, with strong operability.

[0004] Before measurement, the scale factor and offset coefficient of the ring laser gyroscope need to be calibrated. The traditional calibration method is based on the turntable. This calibration method has two problems: First, not all rotation devices have sufficient rotation accuracy to calibrate the ring laser gyroscope. When the rotation accuracy of the rotation device is low, it will inevitably lead to low calibration accuracy. Therefore, this calibration method does not have universality. Second, when using the ring laser gyroscope to calibrate the turntable, the turntable is used to calibrate the ring laser gyroscope, and the ring laser gyroscope is used to calibrate the turntable, resulting in a chaotic traceability relationship, and neither the angular motion parameters of the turntable nor the ring laser gyroscope can achieve traceability.

[0005] Therefore, the existing calibration methods for ring laser gyroscopes have technical problems of lack of universality and inability to achieve traceability of angular motion parameters during calibration. Summary of the Invention

[0006] The embodiments of the present application provide a calibration method for a ring laser gyroscope based on the zero position signal of a circular grating encoder. By introducing the zero position signal of the circular grating encoder (OSE), the scale factor and offset coefficient of the ring laser gyroscope are calibrated, which is applicable to the calibration of ring laser gyroscopes in various scenarios and does not rely on the calibration of the turntable, facilitating the traceability of angular motion parameters.

[0007] The present invention adopts the following technical solutions:

[0008] The present application provides a calibration method for a ring laser gyroscope based on the zero position signal of a circular grating encoder, specifically including the following steps:

[0009] S1. Establish a measurement model for the ring laser gyroscope;

[0010] S2. When the turntable is stationary, collect the measurement pulse count of the ring laser gyroscope, and calculate the offset coefficient for calibrating the measurement model of the ring laser gyroscope according to the measurement pulse count;

[0011] S3. When the turntable rotates uniformly in the forward and reverse directions, respectively collect the measurement data of the ring laser gyroscope and the zero position signal of the circular grating encoder;

[0012] S4. Use the zero position signal to calibrate the measurement data to obtain the scale factor of the measurement model of the ring laser gyroscope;

[0013] S5. Calculate and calibrate the angular increment value of the measurement model of the ring laser gyroscope according to the offset coefficient, scale factor, measurement time and measurement pulse of the ring laser gyroscope;

[0014] S6. Input the offset coefficient, scale factor and angular increment value into the constructed measurement model of the ring laser gyroscope to obtain the calibrated measurement model of the ring laser gyroscope.

[0015] In some specific embodiments, the method for establishing the measurement model of the ring laser gyroscope is as follows:

[0016] According to the scale factor error, the difference between the ring laser gyroscope coordinate system s system composed of the sensitive axes and the carrier coordinate system b system where the rotating tabletop is located, the offset error of the ring laser gyroscope, and the influence of the earth's rotation on the sensitive axis input, construct the measurement model of the ring laser gyroscope:

[0017]

[0018] In the formula is the coordinate transformation matrix from the navigation coordinate system to the turntable coordinate system, is the measurement pulse count of the ring laser gyroscope, S z is the scale factor in the Z-axis direction under the coordinate system, ΔS z is the scale factor error in the Z-axis direction under the coordinate system, is the offset error in the Z-axis direction under the coordinate system, where η zz is the projection of the z-axis of the carrier coordinate system on the z-axis of the ring laser gyroscope coordinate system, θ is the turntable angular displacement, T is the measurement time, Ω is the earth's rotation angular velocity, and L is the local latitude.

[0019] In some specific embodiments, simplify the constructed measurement model of the ring laser gyroscope, delete the cross terms in the measurement model, and obtain the measurement model of the ring laser gyroscope:

[0020]

[0021] In the formula S η ′ represents the scale factor, S η ′=(Sz +ΔS z )η zz , represents the offset coefficient, R = (C 32 Ωcos L + C 33 Ωsin L).

[0022] In some specific embodiments, the specific process of calculating the offset coefficient is as follows:

[0023] S21. Collect the measurement pulse sequence of the ring laser gyroscope within the first preset time T1 when the turntable is stationary, sample the measurement pulse sequence at the first time interval Δt1, and obtain the number of measurement pulses of the ring laser gyroscope within each first time interval;

[0024] S22. Calculate the ratio of each number of measurement pulses to the first time interval to obtain the offset coefficient within each first time interval The calculation formula is:

[0025]

[0026] where, represents the number of measurement pulses of the ring laser gyroscope within the k-th first time interval Δt1, k = 1, 2,..., r,

[0027] S23. Calculate the average value of the offset coefficients within all first time intervals within the first preset time T1 to obtain the offset coefficient of the measurement model of the ring laser gyroscope The calculation formula is:

[0028]

[0029] In some specific embodiments, the acquisition process of step S3 is as follows:

[0030] Count the number of zero-bit pulse signals of the zero-bit signal within the preset time. The preset time includes a complete plurality of zero-bit pulse signals, and obtain the sampling time interval according to the ratio of the preset time to the number of zero-bit pulse signals;

[0031] Intercept the pulse sequence within the preset time from the measured data of the ring laser gyroscope collected, and sample the pulse sequence at the sampling time interval to obtain the number of ring laser gyroscope pulses within each sampling time interval.

[0032] In some specific embodiments, when measuring with the turntable rotating forward at a constant speed, calibrating the measured data using the zero-bit signal specifically includes the following steps:

[0033] S311. Obtain the first pulse sequence of the ring laser gyro within the second preset time T2 from the measured data of the collected ring laser gyro;

[0034] S312. Count the number p of zero - position pulse signals within the second preset time T2 from the collected zero - position signals of the circular grating encoder;

[0035] S313. Sample the first pulse sequence at the second time interval Δt2, and count the number of first pulses of the ring laser gyro within each second time interval Δt2. The second time interval Δt2 is the ratio between the second preset time T2 and the number p of zero - position pulse signals: Δt2 = T2 / p.

[0036] In some specific embodiments, when performing the measurement of the turntable's reverse uniform rotation, using the zero - position signal to calibrate the measured data specifically includes the following steps:

[0037] S321. Obtain the second pulse sequence of the ring laser gyro within the third preset time T3 from the measured data of the collected ring laser gyro;

[0038] S322. Count the number q of zero - position pulse signals within the third preset time T3 from the collected zero - position signals of the circular grating encoder;

[0039] S323. Sample the pulse sequence at the third time interval Δt3, and count the number of second pulses of the ring laser gyro within each third time interval Δt3. The third time interval Δt3 is the ratio between the third preset time T3 and the number q of zero - position pulse signals: Δt3 = T3 / q.

[0040] In some specific embodiments, the specific process of obtaining the scale factor is as follows:

[0041] S41. When the turntable rotates forward at a uniform speed, calculate the first scale factor within each sampling time interval;

[0042]

[0043] Among them, S η2i ′ represents the scale factor within the i - th time interval when the turntable rotates forward at a uniform speed, T 2i represents the i - th sampling time interval when the turntable rotates forward at a uniform speed, is the number of ring laser gyro pulses within the i - th sampling time interval, T1 represents the first preset time when the turntable is stationary, is the total number of measured pulses within the first preset time;

[0044] S42. When the turntable rotates backward at a uniform speed, calculate the second scale factor within each sampling time interval;

[0045]

[0046] Among them, S η3j ' represents the scale factor within the j-th time interval during the reverse uniform rotation of the turntable, and T 3j represents the time interval of the j-th sampling during the reverse uniform rotation of the turntable. is the number of ring laser gyro pulses within the time interval of the j-th sampling;

[0047] S43. Average the first scale factor and the second scale factor over all sampling time intervals to obtain the scale factor S of the ring laser gyro measurement model η ':

[0048]

[0049] Among them, p represents the number of zero position pulse signals during the forward uniform rotation of the turntable, and q represents the number of zero position pulse signals during the reverse uniform rotation of the turntable.

[0050] In some specific embodiments, the specific process of calculating the angular increment value is as follows:

[0051] Obtain the measurement time T of the ring laser gyro and the total number of measurement pulses within the measurement time T

[0052] Input the offset coefficient scale factor S η ', measurement time T, and the total number of measurement pulses into the ring laser gyro measurement model for calculation to obtain the angular increment θ:

[0053]

[0054] S η = 1 / S η '.

[0055] The beneficial effects of the present invention:

[0056] A calibration method for a ring laser gyro based on the zero position signal of a circular grating encoder according to the present invention calibrates the scale factor in the ring laser gyro measurement model based on the zero position signal of the circular grating encoder and the circumferential closure principle, so as to calibrate the ring laser gyro. The present invention can be applied to the precise measurement and calibration of the dynamic motion parameters of a turntable, and solves the problems that the existing calibration method for the scale factor of a ring laser gyro lacks universality and the calibration parameters cannot be traced. Description of the Drawings

[0057] Figure 1It is a flowchart of calibrating a ring laser gyroscope based on the zero position signal of a circular grating encoder in an embodiment of the present application;

[0058] Figure 2 It is a schematic diagram of the coordinate system in a ring laser gyroscope measurement model in an embodiment of the present application;

[0059] Figure 3 It is a schematic diagram of obtaining the measurement pulse number of a ring laser gyroscope when the control turntable is stationary in an embodiment of the present application;

[0060] Figure 4 It is a schematic diagram of an experimental rotation scheme for calibrating a ring laser gyroscope with the zero position signal of a circular grating encoder in an embodiment of the present application;

[0061] Figure 5 It is a schematic diagram of obtaining the measurement pulse number of a ring laser gyroscope when the control turntable rotates forward in an embodiment of the present application;

[0062] Figure 6 It is a schematic diagram of obtaining the measurement pulse number of a ring laser gyroscope when the control turntable rotates backward in an embodiment of the present application. Detailed implementation manners

[0063] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and in no way limits the present invention and its application or use. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0064] Unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions and values set forth in these embodiments do not limit the scope of the present invention.

[0065] At the same time, it should be understood that, for the sake of convenience of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship.

[0066] In addition, for the sake of clarity and conciseness, the descriptions of well-known structures, functions and configurations may be omitted. Those of ordinary skill in the art will recognize that various changes and modifications can be made to the examples described herein without departing from the spirit and scope of the present disclosure.

[0067] The techniques, methods and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the techniques, methods and devices should be regarded as part of the authorization specification.

[0068] In all the examples shown and discussed here, any specific value should be construed as merely exemplary and not as a limitation. Thus, other examples of the exemplary embodiments may have different values.

[0069] Embodiment 1

[0070] As Figure 1 shown, this embodiment provides a calibration method for a ring laser gyroscope based on the zero position signal of a circular grating encoder, which specifically includes the following steps:

[0071] S1. Establish a measurement model for the ring laser gyroscope;

[0072] The method for establishing the measurement model of the ring laser gyroscope is as follows:

[0073] According to the coordinate system as Figure 2 shown, the ring laser gyroscope (RLG) is placed on the rotating table of the platform, and a ring laser gyroscope coordinate system s system composed of the sensitive axes of the ring laser gyroscope, a carrier coordinate system b system where the rotating table of the turntable is located, and a turntable coordinate system t system are constructed. Then, according to the scale factor error, the difference between the coordinate system s system composed of the sensitive axes and the coordinate system b system where the rotating table of the turntable is located, the offset error of the ring laser gyroscope, and the influence of the earth's rotation on the input of the sensitive axis, a measurement model of the ring laser gyroscope is constructed:

[0074]

[0075] In the formula is the coordinate transformation matrix from the navigation coordinate system to the turntable coordinate system, is the number of measurement pulses of the ring laser gyroscope, S z is the scale factor in the Z-axis direction under the coordinate system, ΔS z is the scale factor error in the Z-axis direction under the coordinate system, is the offset error in the Z-axis direction under the coordinate system, where η ij is the projection of the i-axis of the carrier coordinate system on the j-axis of the ring laser gyroscope coordinate system, θ is the angular displacement of the turntable, T is the measurement time, Ω is the earth's rotation angular velocity, and L is the local latitude. The navigation coordinate system is selected as the geographic coordinate system, that is, the x-axis points due east, the y-axis points due north, and the z-axis points vertically upward. The carrier coordinate system b system is fixedly connected to the rotating table of the turntable and rotates with the turntable.

[0076] For the convenience of subsequent calculations, the constructed measurement model of the ring laser gyroscope is simplified, and the cross terms in the measurement model are deleted to obtain the measurement model of the ring laser gyroscope:

[0077]

[0078] In the formula S η′ represents the scale factor, S η ′ = (S z + ΔS z )η zz , represents the offset coefficient, R = (C 32 Ωcos L + C 33 ΩsinL).

[0079] S2. When the turntable is stationary, collect the measurement pulse number of the ring laser gyroscope, and calculate the offset coefficient of the calibration measurement model of the ring laser gyroscope according to the measurement pulse number;

[0080] The specific process of calculating the offset coefficient is as follows:

[0081] S11. Collect the measurement pulse sequence of the ring laser gyroscope within the first preset time T1 when the turntable is stationary, sample the measurement pulse sequence at the first time interval Δt1, and obtain the measurement pulse number of the ring laser gyroscope within each first time interval;

[0082] S12. Calculate the ratio of each measurement pulse number to the first time interval to obtain the offset coefficient within each first time interval The calculation formula is:

[0083]

[0084] where, represents the measurement pulse number of the ring laser gyroscope within the k-th first time interval Δt1, k = 1, 2,..., r,

[0085] S13. Calculate the average value of the offset coefficients within all first time intervals within the first preset time T1 to obtain the offset coefficient of the measurement model of the ring laser gyroscope The calculation formula is:

[0086]

[0087] S3. When the turntable rotates forward and backward at a constant speed, respectively collect the measurement data of the ring laser gyroscope and the zero position signal of the circular grating encoder;

[0088] Count the number of zero position pulse signals of the zero position signal within the preset time. The preset time includes a complete multiple of zero position pulse signals. According to the ratio of the preset time to the number of zero position pulse signals, obtain the sampling time interval;

[0089] Intercept a pulse sequence within a preset time from the measured data of the ring laser gyroscope, and sample the pulse sequence at the sampling time interval to obtain the number of ring laser gyroscope pulses within each sampling time interval.

[0090] Specifically, when measuring the uniform rotation of the turntable in the forward direction, calibrating the measured data using the zero position signal specifically includes the following steps:

[0091] S311. Obtain the first pulse sequence of the ring laser gyroscope within the second preset time T2 from the measured data of the ring laser gyroscope collected;

[0092] S312. Count the number p of zero position pulse signals within the second preset time T2 from the zero position signals of the circular grating encoder collected;

[0093] S313. Sample the first pulse sequence at the second time interval Δt2, and count the first number of pulses of the ring laser gyroscope within each second time interval Δt2. The second time interval Δt2 is the time interval between two adjacent zero position pulse signals, that is, the ratio between the second preset time T2 and the number p of zero position pulse signals: Δt2 = T2 / p.

[0094] Similarly, when measuring the uniform rotation of the turntable in the reverse direction, calibrating the measured data using the zero position signal specifically includes the following steps:

[0095] S321. Obtain the second pulse sequence of the ring laser gyroscope within the third preset time T3 from the measured data of the ring laser gyroscope collected;

[0096] S322. Count the number q of zero position pulse signals within the third preset time T3 from the zero position signals of the circular grating encoder collected;

[0097] S323. Sample the pulse sequence at the third time interval Δt3, and count the second number of pulses of the ring laser gyroscope within each third time interval Δt3. The third time interval Δt3 is the ratio between the third preset time T3 and the number q of zero position pulse signals: Δt3 = T3 / q.

[0098] S4. Calibrate the measured data using the zero position signal to obtain the scale factor of the ring laser gyroscope measurement model;

[0099] The specific process of obtaining the scale factor is as follows:

[0100] S41. When the turntable rotates uniformly in the forward direction, calculate the first scale factor within each sampling time interval;

[0101]

[0102] Among them, S η2i′ represents the scale factor within the i-th time interval during the forward uniform rotation of the turntable, T 2i represents the time interval of the i-th sampling during the forward uniform rotation of the turntable, is the number of ring laser gyro pulses within the i-th sampling time interval, T1 represents the first preset time when the turntable is stationary, is the total number of measurement pulses within the first preset time T1;

[0103] S42. During the reverse uniform rotation of the turntable, calculate the second scale factor within each sampling time interval;

[0104]

[0105] wherein, S η3j ′ represents the scale factor within the j-th time interval during the reverse uniform rotation of the turntable, T 3j represents the time interval of the j-th sampling during the reverse uniform rotation of the turntable, is the number of ring laser gyro pulses within the j-th sampling time interval;

[0106] S43. Average the first scale factor and the second scale factor within all sampling time intervals to obtain the scale factor S η ′ of the ring laser gyro measurement model:

[0107]

[0108] wherein, p represents the number of zero position pulse signals during the forward uniform rotation of the turntable, and q represents the number of zero position pulse signals during the reverse uniform rotation of the turntable.

[0109] S5. Calculate the angular increment value for calibrating the ring laser gyro measurement model according to the offset coefficient, the scale factor, and the measurement time and measurement pulses of the ring laser gyro;

[0110] The specific process of calculating the angular increment value is as follows:

[0111] Obtain the measurement time T of the ring laser gyro and the total number of measurement pulses within the measurement time T

[0112] Input the offset coefficient scale factor S η ′, measurement time T, and the total number of measurement pulses into the ring laser gyro measurement model for calculation to obtain the angular increment θ:

[0113]

[0114] S η = 1 / S η ′.

[0115] S6. Input the offset coefficient, scale factor, and angular increment value into the constructed ring laser gyro measurement model to obtain a calibrated ring laser gyro measurement model.

[0116] As an example, the turntable can be controlled to return to zero and remain stationary within the time range of 0 to T1, where T1 = 120 s. Obtain the number of pulses of the ring laser gyro within a fixed time interval Δt1 = 1 s and record them in sequence as As Figure 3 shown, according to the simplified ring laser gyro measurement model, it can be obtained that:

[0117]

[0118] Reduce the error to obtain the offset coefficient

[0119]

[0120] Substitute the values and calculate the offset coefficient according to the above formula The result can be calculated as

[0121] Then, in actual operation, control the turntable to rotate according to the rule as Figure 4 shown (only need to rotate more than 3600°, in this embodiment, 3630° is taken as an example), where the time interval between adjacent two circles is ΔT = 8 s, the angular rate is set to 30° / s, and the angular acceleration rate is set to 30° / s 2 . From Figure 4 the shown rotation scheme, it can be seen that the turntable rotates 30 circles forward at a constant speed and 30 circles backward at a constant speed. Record the measurement pulses of the ring laser gyro within the time interval of the adjacent zero position pulse signals of the circular grating encoder. In this article, the total time for rotating 30 circles forward (each zero position signal triggers the ring laser gyro to rotate one circle forward) is T2 (excluding the interval ΔT for each circle), and the total time for rotating 30 circles backward (each zero position signal triggers the ring laser gyro to rotate one circle backward) is T3 (excluding the interval ΔT for each circle).

[0122] Specifically, when performing the forward uniform rotation measurement of the turntable, simultaneously collect the measurement data S RLG of the ring laser gyro and the zero position signal S OSE of the circular grating encoder. As Figure 5 shown, obtain the number of pulses of the ring laser gyro within the time period from t2 to t2 + T2. The time period from t2 to t2 + T2 includes a total of p zero position pulse signals. The time intervals between adjacent zero position pulse signals of the circular grating encoder are recorded as T 21 , T 22 , …, T 2p, and their corresponding turntable angular displacements are all 360°. The number of measurement pulses of the ring laser gyroscope within these time intervals are sequentially denoted as As Figure 5 shown.

[0123] When performing the measurement of the reverse uniform rotation of the turntable, the measurement data of the ring laser gyroscope and the zero position signal of the circular grating encoder are collected simultaneously, and the number of pulses of the ring laser gyroscope within the time period from t3 to t3 + T3 is obtained. There are q zero position pulse signals in total within the time period from t3 to t3 + T3. The time intervals between adjacent zero position pulse signals of the circular grating encoder are sequentially denoted as T 31 , T 32 , …, T 3q , and their corresponding turntable angular displacements are all 360°. The number of measurement pulses of the ring laser gyroscope within these time intervals are sequentially denoted as As Figure 6 shown.

[0124] Then, according to Figures 5 - 6 the collected data, the scale factor is calculated. Exemplarily, when calculating the scale factor in the measurement model of the ring laser gyroscope, from the simplified ring laser measurement model, the scale factor S η2i ' for the i-th second time interval calculated by controlling the forward rotation of the turntable is:

[0125]

[0126] The scale factor S η3j ' for the j-th third time interval calculated by controlling the reverse rotation of the turntable is:

[0127]

[0128] The scale factor S η ' is calculated by reducing the error:

[0129]

[0130] According to the rotation law as Figure 4 , the data is collected according to the steps in step S3, and the scale factor is calculated using the above formula, and the result is S η ' = 1.382585976.

[0131] According to the calculated scale factor S η ', let S η = 1 / S η ', then the relationship between the number of measurement pulses of the ring laser gyroscope and the angular increment θ is:

[0132]

[0133] where T is the measurement time of the ring laser gyro. The offset coefficient obtained above and the scale factor S η ′ = 1.382585976, the angular increment value can be calculated from the known measurement time and measurement pulses in the measurement of the ring laser gyro.

[0134] Among them, the number of measurement pulses is output by the ring laser gyro based on its measurement principle when the turntable rotates. The number of measurement pulses depends on the rotation angle of the turntable. For example, when the ring laser gyro rotates 10° with the turntable, it outputs the corresponding number of measurement pulses 100. As long as other measurement conditions remain unchanged and the turntable rotates 10°, it is 100. Therefore, after the turntable rotates a certain angle, it becomes a known quantity. The acquisition of the measurement time T is realized by the timing function in the ring laser acquisition box. That is, in the external trigger mode, the ring laser gyro acquisition box can time the interval between two adjacent trigger signals input, and the interval time of the output adjacent trigger signals (i.e., zero position signals) is T. In this article, T is the time interval between two zero position signals when rotating a complete circle (there are two zero position signals in a complete circle, and 1 T can be obtained. There are three zero position signals in two consecutive complete circles, and 2 Ts can be obtained).

[0135] It can be understood that as long as there is a trigger signal, and T can be obtained from the upper computer of the ring laser gyro. After calibration, S η is calculated, after calibration, through this formula, θ can be calculated. The calibration method in this article is an inverse process. In fact, it is to give the ring laser gyro an accurate angle. As shown in the following figure, during calibration , the turntable is made stationary, that is, θ = 0°, and then the and T output by the upper computer of the ring laser gyro are recorded, then when calibrating S η ′ (S η ′ = 1 / S η ), the turntable is rotated a complete circle, and the circular grating encoder outputs two zero position signals to trigger the ring laser gyro. When the two zero position signals trigger, it can be considered that the turntable has rotated 360°, that is, θ = 360°. Then the and T output by the upper computer of the ring laser gyro are recorded, then Theoretically, S η ′ can be calculated after rotating a complete circle. However, in order to reduce the calibration error, this article uses 30 forward rotations and 30 reverse rotations to calculate 60 S η ′ and then take the average.

[0136] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Based on the technical essence of the present invention, any simple modifications, equivalent replacements, and improvements made to the above embodiments within the spirit and principles of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A ring laser gyro calibration method based on a circular grating encoder zero position signal, characterized in that: The specific steps include: S1. Establish a ring laser gyro measurement model; S2, collecting the number of measurement pulses of the ring laser gyro when the turntable is stationary, and calculating the offset coefficient of the ring laser gyro measurement model for calibration according to the number of measurement pulses; S3, when the turntable rotates at a constant speed in the forward and reverse directions, respectively collect the measurement data of the ring laser gyro and the zero position signal of the circular grating encoder; S4, calibrating the measurement data using the zero-position signal to obtain a scale factor of the ring laser gyro measurement model; The specific process of obtaining the scale factor is: S41, when the turntable rotates at a uniform speed in the forward direction, calculating the first scale factor within each sampling time interval; Among them, S η2i ′ represents the scale factor in the i-th time interval when the turntable rotates at a uniform speed in the positive direction, T 2i represents the time interval of the ith sampling when the turntable rotates at a uniform speed in the positive direction, is the number of ring laser gyro pulses in the i-th sampling time interval, T1 represents the first preset time when the turntable is stationary, is the total number of measured pulses within the first preset time; S42, when the turntable rotates in the reverse direction at a uniform speed, calculating the second scale factor within each sampling time interval; Among them, S η3j ′ represents the scale factor in the jth time interval when the turntable rotates in the reverse direction at a uniform speed, T 3j represents the time interval of the jth sampling when the turntable rotates in the reverse direction at a uniform speed, is the number of ring laser gyro pulses in the jth sampling time interval; S43, averaging the first scale factor and the second scale factor in all sampling time intervals to obtain a scale factor S of the ring laser gyro measurement model. η ′: Wherein, p represents the number of zero-position pulse signals when the turntable rotates at a uniform speed in the forward direction, and q represents the number of zero-position pulse signals when the turntable rotates at a uniform speed in the reverse direction; S5, calculating an angular increment value for calibrating a ring laser gyro measurement model according to the offset coefficient, the scale factor, and the measurement time and measurement pulse of the ring laser gyro; The specific process of calculating the angular increment value is: Get the measurement time T of the ring laser gyro and the total number of measurement pulses within the measurement time T The offset coefficient Scale factor S η ′, measurement time T and total number of measurement pulses Input it into the ring laser gyro measurement model to calculate and obtain the angular increment θ: S η =1 / S η ′。 2. The ring laser gyro calibration method based on the zero position signal of the circular grating encoder according to claim 1 is characterized in that: The method to establish the ring laser gyro measurement model is: According to the scale factor error, the difference between the ring laser gyro coordinate system s composed of the sensitive axis and the carrier coordinate system b where the rotating table of the turntable is located, the offset error of the ring laser gyro and the influence of the earth's rotation on the sensitive axis input, the measurement model of the ring laser gyro is constructed: In the formula is the coordinate transformation matrix from the navigation coordinate system to the turntable coordinate system, is the measurement pulse number of the ring laser gyro, S z is the scale factor in the Z-axis direction of the coordinate system, ΔS z is the scale factor error in the Z-axis direction of the coordinate system, is the offset error in the Z-axis direction in the coordinate system, where η zz is the projection of the z-axis of the carrier coordinate system on the z-axis of the ring laser gyro coordinate system, η xz is the projection of the x-axis of the carrier coordinate system on the z-axis of the ring laser gyro coordinate system, η yz is the projection of the y-axis of the carrier coordinate system on the z-axis of the ring laser gyro coordinate system, θ is the angular displacement of the turntable, T is the measurement time, Ω is the angular rate of the earth's rotation, and L is the local latitude.

3. The ring laser gyro calibration method based on the zero position signal of the circular grating encoder according to claim 2 is characterized in that: The constructed measurement model of the ring laser gyroscope is simplified, and the cross terms in the measurement model are deleted to obtain the measurement model of the ring laser gyroscope: Where S η ′ represents the scale factor, S η ′=(S z +ΔS z )η zz , represents the offset coefficient, R=(C 32 Ωcos L+C 33 ΩsinL).

4. The ring laser gyro calibration method based on the zero position signal of the circular grating encoder according to claim 3 is characterized in that: The specific process of calculating the offset coefficient is: S21, collecting a measurement pulse sequence of the ring laser gyro within a first preset time T1 when the turntable is stationary, sampling the measurement pulse sequence according to a first time interval Δt1, and obtaining the number of measurement pulses of the ring laser gyro within each first time interval; S22, calculating the ratio of each measured pulse number to the first time interval to obtain the offset coefficient within each first time interval The calculation formula is: in, represents the number of measurement pulses of the ring laser gyro in the kth first time interval Δt1, k=1,2,…,r, S23, calculating the average value of the offset coefficients in all first time intervals within the first preset time T1, and obtaining the offset coefficient of the ring laser gyro measurement model The calculation formula is:

5. The ring laser gyro calibration method based on the zero position signal of the circular grating encoder according to claim 4 is characterized in that: The collection process of step S3 is: Counting the number of zero-position pulse signals of the zero-position signal within a preset time, the preset time includes a plurality of complete zero-position pulse signals, and obtaining a sampling time interval according to a ratio of the preset time to the number of zero-position pulse signals; A pulse sequence within a preset time is intercepted from the collected measurement data of the ring laser gyro, and the pulse sequence is sampled according to a sampling time interval to obtain the number of ring laser gyro pulses within each sampling time interval.

6. The ring laser gyro calibration method based on the zero position signal of the circular grating encoder according to claim 5 is characterized in that: When the turntable is rotating at a uniform speed in the forward direction for measurement, calibrating the measurement data using the zero position signal specifically includes the following steps: S311, acquiring a first pulse sequence of the ring laser gyro within a second preset time T2 from the collected measurement data of the ring laser gyro; S312, counting the number p of zero-position pulse signals within a second preset time T2 from the collected zero-position signal of the circular grating encoder; S313, sampling the first pulse sequence according to the second time interval Δt2, and counting the number of first pulses of the ring laser gyroscope in each second time interval Δt2, where the second time interval Δt2 is the ratio of the second preset time T2 to the number p of zero-position pulse signals: Δt2=T2 / p.

7. The ring laser gyro calibration method based on the zero position signal of the circular grating encoder according to claim 5, characterized in that: When performing the measurement of the turntable's reverse uniform rotation, calibrating the measurement data using the zero position signal specifically includes the following steps: S321, acquiring a second pulse sequence of the ring laser gyro within a third preset time T3 from the collected measurement data of the ring laser gyro; S322, counting the number q of zero-position pulse signals within a third preset time T3 from the collected zero-position signal of the circular grating encoder; S323, sampling the pulse sequence according to the third time interval Δt3, and counting the number of second pulses of the ring laser gyroscope in each third time interval Δt3, where the third time interval Δt3 is the ratio of the third preset time T3 to the number of zero-position pulse signals q: Δt3=T3 / q.

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