On-site rapid calibration method and device for north seeker based on MEMS gyroscope

Abstract

The invention provides a north seeker field rapid calibration method and device based on an MEMS gyroscope. The method comprises the following steps: establishing a parameter error equation of a triaxial MEMS gyroscope; calculating a non-orthogonal error and a scale factor error of the MEMS gyroscope according to test data obtained by respectively rotating a circle clockwise and anticlockwise around three coordinate axes of the north seeker; calculating a constant drift error of the MEMS gyroscope through data acquired at a positive position and a negative position; calibration error parameters are verified through north-seeking calculation of the north seeker. Through the technical scheme of the invention, the rapid field calibration of the MEMS gyroscope north seeker is realized without depending on a traditional high-precision three-axis rate turntable, so that the dependence on equipment and environment is reduced, and the calibration process is more convenient and efficient.

Description

Technical Field

[0001] The invention belongs to the technical field of gyro orientation north finding, and in particular relates to a method and device for rapid on-site calibration of a north finder based on a MEMS gyroscope. Background Art

[0002] Inertial north-seeking has high reliability and stable performance. Except for the high latitude limit, it is not affected by external environmental factors such as weather, topography, day and night time, magnetic field, etc. It is widely used in launch devices, well logging, geological exploration and other fields.

[0003] The calibration accuracy of the gyroscope directly affects the north-seeking accuracy of the north-finder. At present, the calibration of the north-finder mostly relies on a high-precision three-axis rate turntable. The calibration method is complicated, and because the error coefficients of the MEMS gyroscope are not fixed, the parameters such as the constant drift error and scale factor of the MEMS gyroscope will change with the storage or use time. Therefore, the MEMS gyroscope needs to be calibrated regularly. The on-site rapid calibration method of the north-finder based on the MEMS gyroscope can replace the regular calibration, and the on-site calibration method does not rely on high-precision instruments such as multi-axis turntables, which improves the north-seeking accuracy of the MEMS gyroscope. Summary of the invention

[0004] In view of this, the present invention provides a method for rapid on-site calibration of a north-finder based on a MEMS gyroscope, comprising the following steps:

[0005] Step 1: Establish the parameter error equation of the three-axis MEMS gyroscope;

[0006] Step 2: Calculate the non-orthogonality error and scale factor error of the MEMS gyroscope by using the test data of rotating one circle clockwise and counterclockwise around the three coordinate axes of the north finder;

[0007] Step 3: Calculate the constant drift error of the MEMS gyroscope through the data collected from the positive and negative positions;

[0008] Step 4: Verify the calibration error parameters through the north-seeking calculation of the north-seeker.

[0009] In particular, in step 1, the parameter error equation of the three-axis MEMS gyroscope is established as follows:

[0010]

[0011] Where W x , W y , W z are the actual output values ​​of the three axes of the MEMS gyroscope; ω x0 ,ω y0 ,ω z0 is the constant drift of the MEMS gyroscope; ωx ,ω y ,ω z is the theoretical input value of the MEMS gyroscope; S kx , S ky , S kz is the scale factor of the MEMS gyroscope; K xy , K xz , K yx , K yz , K zx , K zy is the non-orthogonal error coefficient of the MEMS gyroscope.

[0012] In particular, in the step 2, the non-orthogonal error and scale factor error of the MEMS gyroscope do not require the use of a traditional high-precision three-axis rate turntable, but only require the use of an ordinary horizontal platform. By keeping the north-finder manually rotated one circle in any direction against the side of the horizontal platform, it can return to the same position. The three coordinate axes of the north-finder are placed downward on the horizontal platform respectively, and the data of one circle of forward and reverse rotation are collected and calculated.

[0013] In particular, in the step three, the constant drift error of the MEMS gyroscope is calculated by using a simple horizontal platform to collect data from two positions, one positive and one negative.

[0014] In particular, in step 4, the calibration error parameters are verified by the north-seeking calculation of the north-seeker, and the azimuth angle calculation is performed by Calculated.

[0015] is the Earth's rotation angular velocity in the north direction in the geodetic coordinate system, the pitch angle β, the roll angle γ Indicates the three-axis angular rate measured by the three-axis MEMS gyroscope.

[0016] The present invention also proposes a device for rapid on-site calibration of a north-seeking instrument based on a MEMS gyroscope, comprising:

[0017] A parameter error equation building module is used to build the parameter error equation of the three-axis MEMS gyroscope;

[0018] A non-orthogonal error and scale factor error calculation module is used to calculate the non-orthogonal error and scale factor error of the MEMS gyroscope through test data of one rotation clockwise and one rotation counterclockwise around the three coordinate axes of the north finder;

[0019] The constant drift error calculation module calculates the constant drift error of the MEMS gyroscope through data collected from two positions, one positive and one negative;

[0020] The calibration error parameter calculation module is used to verify the calibration error parameters through the north-seeking calculation of the north-seeking instrument.

[0021] Beneficial effects:

[0022] Through the technical solution of the present invention, rapid on-site calibration of the MEMS gyroscope north finder is achieved, and it is no longer dependent on the traditional high-precision three-axis rate turntable, thereby reducing dependence on equipment and environment, making the calibration process more convenient and efficient.

[0023] The technical solution of the present invention overcomes the influence of constant drift, non-orthogonal error and scale factor error of the MEMS gyroscope during use, ensuring that a high north-seeking accuracy can be maintained under different use conditions.

[0024] Through the technical solution of the present invention, the automatic collection and processing of the positive and negative rotation data of the north-seeking instrument in each axis is realized, the influence of drift error and the earth's rotation angular rate is effectively eliminated, and the accuracy of the north-seeking result is significantly improved.

[0025] The technical solution of the present invention greatly reduces the difficulty of calibrating the north-finder, so that the calibration operation can be easily completed on site, with stronger adaptability, and is particularly suitable for scenarios that require frequent debugging and rapid deployment. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the structural composition of the north-finder in the present invention.

[0027] Figure 2 Schematic diagram of the relationship between the carrier coordinate system of the north-finder and the geographic coordinate system. DETAILED DESCRIPTION

[0028] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0029] As attached Figure 1 As shown, the north finder is composed of a three-axis MEMS acceleration sensor (Acc), a three-axis MEMS gyroscope (Wx, Wy, Wz) and a corresponding data acquisition and processing system. The three-axis MEMS acceleration sensor is used to measure the three-axis acceleration data, and the three-axis MEMS gyroscope is used to measure the three-axis angular rate data.

[0030] In the present invention, the geographic coordinate system refers to the north-east coordinate system, in which the X-axis of the geographic coordinate system points to the north, the Y-axis and the X-axis point to the east, and the Z-axis points vertically downward. The carrier coordinate system refers to a coordinate system relatively fixed to the carrier platform, and the north finder is installed along the carrier coordinate system. The X-axis of the carrier coordinate system points to the front along the longitudinal axis of the carrier, the Y-axis points to the right along the transverse axis of the carrier, and the Z-axis points downward, forming a right-handed coordinate system with the X and Y axes, as shown in the attached figure. Figure 2As shown. The azimuth measurement range is 0° to 360°, 0° when pointing to due north, and positive when rotating clockwise; the pitch angle measurement range is -90° to 90°, 0° when horizontal, positive when looking up, and negative when looking down; the roll angle measurement range is -180° to 180°, 0° when horizontal, positive when tilting to the right, and negative when tilting to the left. The length direction of the north finder is the forward direction, corresponding to the X-axis of the three-axis gyroscope and the A-axis of the three-axis accelerometer. The right direction of the north finder corresponds to the Y-axis of the three-axis gyroscope and the B-axis of the three-axis accelerometer. The vertical downward direction of the north finder corresponds to the Z-axis of the three-axis gyroscope and the C-axis of the three-axis accelerometer. The three directions constitute a right-handed coordinate system.

[0031] The accuracy of the MEMS gyroscope directly affects the accuracy of north-seeking, which is mainly manifested in the drift of the fixed constant value of the MEMS gyroscope, the sensitivity error of the gyroscope, and the scale factor error. Since the linearity of the MEMS gyroscope is very good, the mathematical model of the MEMS gyroscope output can be obtained by ignoring the quadratic cross term:

[0032]

[0033] Where W x , W y , W z are the actual output values ​​of the three axes of the MEMS gyroscope; ω x0 ,ω y0 ,ω z0 is the constant drift of the MEMS gyroscope; ω x ,ω y ,ω z is the theoretical input value of the MEMS gyroscope; S kx , S ky , S kz is the scale factor of the MEMS gyroscope; K xy , K xz , K yx , K yz , K zx , K zy is the non-orthogonal error coefficient of the MEMS gyroscope.

[0034] Place the north finder horizontally on a horizontal platform with the Z axis facing downward. Keep the north finder fixed at any initial position. After its output is stable, manually rotate the north finder clockwise around the Z axis and return to the initial position. After its output is stable, rotate it counterclockwise around the Z axis (-360°) and record the output data of the three-axis gyroscope during the rotation.

[0035] Integrating both sides of formula (1) simultaneously yields:

[0036]

[0037] The integral value on the left side of formula (1) can be obtained by integrating the output data of the three-axis gyroscope. When the north finder rotates clockwise around the Z axis, Among them, t0 and t1 are the start time and end time of clockwise rotation respectively. When the north finder rotates counterclockwise around the Z axis, Among them, t2 and t3 are the start time and end time of clockwise rotation respectively. Subtracting the data of one clockwise rotation from the data of one counterclockwise rotation can eliminate the influence of constant drift and the angular rate of the earth's rotation. Expanding the matrix after subtracting the two equations can be obtained:

[0038]

[0039] in, is the integrated value of the three-axis acceleration when rotating clockwise, is the integral value of the three-axis acceleration when rotating counterclockwise. K can be calculated by formula (3): xz , K yz , S kz .

[0040] Similarly, place the north finder on a horizontal platform with the X axis facing downward, and rotate it clockwise and counterclockwise around the X axis to calculate S kx , K yx , K zx Place the north finder on a horizontal platform with the Y axis facing downwards, and rotate it clockwise and counterclockwise around the Y axis to calculate K xy , S ky , K zy .

[0041] The non-orthogonality error and scale factor error coefficient of the gyroscope are calculated by using the test data of one rotation clockwise and one counterclockwise around the three coordinate axes of the north finder.

[0042] Place the north-finder horizontally on a horizontal platform with the Z axis facing downward. Keep the north-finder stationary along any side and record the output of the three-axis gyroscope at this time (t+ moment). Rotate the north-finder 180° around the Z axis (the outputs of the X axis and the Y axis are in opposite directions) and record the output of the three-axis gyroscope at this time (t- moment).

[0043] Adding the outputs at time t+ and time t- gives:

[0044]

[0045] The theoretical outputs of the X-axis and Y-axis gyroscopes on the north finder at time t+ and time t- are equal in magnitude and opposite in direction, that is:

[0046]

[0047] Substituting equation (5) into equation (4) yields ω x0 and ω y0 .

[0048] Similarly, place the north finder on a horizontal platform with the X axis facing downward, rotate the north finder 180° around the X axis, and record the output of the three-axis gyroscope at two positions to obtain ω. z0 .

[0049] By using a simple horizontal platform to approach the edge, the constant drift error of the MEMS gyroscope is calculated through the data collected from two positions, one positive and one negative.

[0050] Substituting the calculated non-orthogonal error, scale factor error and constant drift error parameters back into formula (1), the theoretical input value of the three-axis gyroscope is obtained, which is the corrected three-axis gyroscope output:

[0051]

[0052] According to the Euler rotation relationship, the matrix representation of the conversion relationship between the carrier coordinate system (b system) and the geographic coordinate system (n system) can be obtained:

[0053]

[0054] Among them, β is the pitch angle, γ is the roll angle, and α is the azimuth angle.

[0055] The calculation method of pitch angle β and roll angle γ is: the horizontal projection of the earth's gravitational acceleration in the geographic coordinate system is 0, and the value in the vertical downward direction is g, then:

[0056]

[0057] In the formula, is the value of the three-axis acceleration measured in the coordinate system of the north-seeker carrier. By solving equation (2), the pitch angle β and the roll angle γ can be calculated:

[0058]

[0059] Similarly, the theoretical value of the three-axis angular rate measured by the north finder in the carrier coordinate system is It can be obtained by the following formula (6):

[0060]

[0061] in, are the projections of the Earth's rotation angular rate in the north direction and the vertical downward direction in the geodetic coordinate system, ω ie is the Earth's rotation angular rate, and L is the local latitude.

[0062] Expanding equation (6) yields the three-axis angular velocity measured by the three-axis MEMS gyroscope:

[0063]

[0064] Based on this solution, the azimuth angle is calculated as:

[0065]

[0066] The present invention also discloses a device for rapid on-site calibration of a north-seeking instrument based on a MEMS gyroscope, comprising:

[0067] A parameter error equation building module is used to build the parameter error equation of the three-axis MEMS gyroscope;

[0068] A non-orthogonal error and scale factor error calculation module is used to calculate the non-orthogonal error and scale factor error of the MEMS gyroscope through test data of one rotation clockwise and one rotation counterclockwise around the three coordinate axes of the north finder;

[0069] The constant drift error calculation module calculates the constant drift error of the MEMS gyroscope through data collected from two positions, one positive and one negative;

[0070] The calibration error parameter calculation module is used to verify the calibration error parameters through the north-seeking calculation of the north-seeking instrument.

[0071] In summary, the above are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

[0072] It is obvious to those skilled in the art that the embodiments of the present invention are not limited to the details of the above exemplary embodiments, and that the embodiments of the present invention can be implemented in other specific forms without departing from the spirit or basic features of the embodiments of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the embodiments of the present invention is limited by the attached claims rather than the above description, so it is intended to include all changes that fall within the meaning and scope of the equivalent elements of the claims in the embodiments of the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved. In addition, it is obvious that the word "comprising" does not exclude other units or steps, and the singular does not exclude the plural. Multiple units, modules or devices stated in the system, device or terminal claims can also be implemented by the same unit, module or device through software or hardware. The words first, second, etc. are used to indicate names, and do not indicate any particular order.

[0073] Finally, it should be noted that the above implementation modes are only used to illustrate the technical solutions of the embodiments of the present invention and are not intended to limit them. Although the embodiments of the present invention have been described in detail with reference to the above preferred implementation modes, those skilled in the art should understand that the technical solutions of the embodiments of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for rapid on-site calibration of a north-seeking instrument based on a MEMS gyroscope, characterized in that: The following steps are involved: Step 1: Establish the parameter error equation of the three-axis MEMS gyroscope; Step 2: Calculate the non-orthogonality error and scale factor error of the MEMS gyroscope by using the test data of rotating one circle clockwise and counterclockwise around the three coordinate axes of the north finder; Step 3: Calculate the constant drift error of the MEMS gyroscope through the data collected from the positive and negative positions; Step 4: Verify the calibration error parameters through the north-seeking calculation of the north-seeker.

2. The method for rapid on-site calibration of a north-seeker based on a MEMS gyroscope as claimed in claim 1, characterized in that: In step 1, the parameter error equation of the three-axis MEMS gyroscope is established as follows: Where W x , W y , W z They are the actual output values ​​of the three axes of the MEMS gyroscope; ω x0 ,ω y0 ,ω z0 is the constant drift of the MEMS gyroscope; ω x ,ω y ,ω z is the theoretical input value of the MEMS gyroscope; S kx , S ky , S kz is the scale factor of the MEMS gyroscope; K xy , K xz , K yx , K yz , K zx , K zy is the non-orthogonal error coefficient of the MEMS gyroscope.

3. The method for rapid on-site calibration of a north-seeking instrument based on a MEMS gyroscope as claimed in claim 1, characterized in that: In the step 2, the non-orthogonal error and scale factor error of the MEMS gyroscope do not require the use of a traditional high-precision three-axis rate turntable, but only require the use of an ordinary horizontal platform. By manually rotating the north-finder in any direction against the side of the horizontal platform for one circle, the north-finder can return to the same position. The three coordinate axes of the north-finder are placed downward on the horizontal platform, and the data of one forward and reverse rotation are collected and calculated.

4. The method for rapid on-site calibration of a north-seeking instrument based on a MEMS gyroscope as claimed in claim 1, characterized in that: In the step three, the constant drift error of the MEMS gyroscope is calculated by using a simple horizontal platform to collect data from two positions, one positive and one negative.

5. The method for rapid on-site calibration of a north-seeking instrument based on a MEMS gyroscope as claimed in claim 1, characterized in that: In step 4, the calibration error parameters are verified by the north-seeking calculation of the north-seeker. The azimuth angle calculation is performed by Calculated. is the Earth's rotation angular velocity in the north direction in the geodetic coordinate system, the pitch angle β, the roll angle γ Indicates the three-axis angular rate measured by the three-axis MEMS gyroscope.

6. A device for rapid on-site calibration of a north-seeking instrument based on a MEMS gyroscope, characterized in that: include: A parameter error equation building module is used to build the parameter error equation of the three-axis MEMS gyroscope; A non-orthogonal error and scale factor error calculation module is used to calculate the non-orthogonal error and scale factor error of the MEMS gyroscope through test data of one rotation clockwise and one rotation counterclockwise around the three coordinate axes of the north finder; The constant drift error calculation module calculates the constant drift error of the MEMS gyroscope through data collected from two positions, one positive and one negative; The calibration error parameter calculation module is used to verify the calibration error parameters through the north-seeking calculation of the north-seeking instrument.

Images