Translocation self-calibration method for strapdown gyroscope north seeker

Abstract

The invention relates to a translocation self-calibration method for a strapdown gyroscope north finder, which comprises the following steps of: 1, fixedly arranging the strapdown gyroscope north finder on a turntable through a structural reference leaning surface of the strapdown gyroscope north finder, and enabling a heading shaft of the strapdown gyroscope north finder to be parallel to an outer frame shaft of the turntable; 2, controlling a motor of the strapdown gyroscope north seeker to rotate to a first north seeking position; 3, controlling an outer frame of the rotary table to rotate at a constant speed, controlling a motor of the strapdown gyroscope north seeker to sequentially translocate in a range of + / -m degrees of a first north seeking position according to n degrees, and staying at the position after each translocation for t seconds to sample gyroscope data of the strapdown gyroscope north seeker; 4, processing the sampling data in the step 3 to obtain a first position of motor transposition for north seeking of the strapdown gyroscope north seeker; and 5, controlling the motor of the strapdown gyroscope north seeker to sequentially translocate to a second position, a third position and a fourth position for north seeking, and repeating the steps 3 and 4 to obtain the second position, the third position and the fourth position of the north seeking motor of the strapdown gyroscope north seeker to be calibrated. The calibration difficulty is reduced, and the calibration efficiency is improved.

Description

Technical Field

[0001] The invention relates to a strapdown gyro north finder orientation technology, in particular to a strapdown gyro north finder rotation self-calibration method. Background Art

[0002] A strapdown gyroscopic north finder is an orientation-finding instrument used for azimuth measurement. Utilizing the principle that gyros sense the angular velocity of Earth's rotation, strapdown gyroscopic north finders can autonomously find north based on Earth's rotation and provide a north reference. Even in harsh environments, such as satellite failures, strapdown gyroscopic north finders can achieve autonomous north finding without relying on other conditions, offering significant technical advantages and promising prospects in practical applications.

[0003] Common strapdown gyro north finders all use a multi-position north-finding solution that relies on motor rotation rather than mechanical limits. This rotation accuracy can severely limit the device's north-finding accuracy. To reduce costs, low-cost strapdown gyro north finders all use encoders with lower accuracy but better repeatability. However, achieving high-precision north-finding requires high-precision calibration of the motor's four rotation positions. Due to the low accuracy of the encoder, the four rotation positions of the north-finding motor are not strictly 90° apart in the encoder. Therefore, high-precision calibration is required based on an external angular reference to determine the four rotation encoder positions of the north-finding motor. This calibration operation is difficult to implement and requires the design of an external calibration solution.

[0004] Currently, the most common calibration method uses an autocollimator combined with a theodolite, or a variant of this method. This requires two people to calibrate a device for a full day, resulting in low calibration efficiency and severely limiting production efficiency. Therefore, it is urgent to develop a highly efficient, time-saving, and labor-saving method for the self-calibration of a strapdown gyro north finder with high calibration accuracy. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the present invention proposes a self-calibration method for the rotation of a strapdown gyro north finder.

[0006] The above-mentioned purpose of the present invention is achieved through the following technical solutions: A strapdown gyro north finder rotation self-calibration method is characterized in that: all four rotation positions of the strapdown gyro north finder motor are obtained through a self-calibration, including the following steps: Step 1: Fixing a strapdown gyro north finder on a turntable via its structural reference surface, wherein the heading axis of the strapdown gyro north finder is parallel to the outer frame axis of the turntable; Step 2: Control the motor of the strapdown gyro north finder to rotate to the first north-seeking position 0°; Step 3: Control the outer frame of the turntable to rotate at a constant speed of a° / s, and at the same time control the motor of the strapdown gyro north finder to rotate in sequence within the range of ±m° of the first north-seeking position 0° in steps of n°, and stay at the position after each rotation for t seconds to perform gyro data sampling of the strapdown gyro north finder; Step 4: Process the sampled data of step 3 to obtain the first position of the north-seeking motor of the strapdown gyro north-seeker; Step 5: Control the motor of the strapdown gyro north finder to rotate to the second north-seeking position of 90°, the third position of 180°, and the fourth position of 270° in sequence. Repeat steps 3 and 4 at each position to obtain the second, third, and fourth positions of the north-seeking motor of the strapdown gyro north finder to be calibrated. All four positions of the north-seeking motor of the strapdown gyro north finder are obtained through one self-calibration.

[0007] Moreover, in step 3, a is set to 20, m is set to 0.7, n is set to 0.05, and t is set to 18.

[0008] Moreover, step 4 specifically includes: after completing all the rotation sampling within the range of ±n° of the first position 0° of the north-seeking, obtaining the data scatter points whose horizontal coordinates are the encoder values ​​of the strapdown gyro north-seeking instrument and whose vertical coordinates are the gyro angular velocity of the strapdown gyro north-seeking instrument; then performing sinusoidal curve fitting on the data scatter points to obtain the maximum or minimum value of the vertical coordinate of the sine curve within the range of ±n°, and the horizontal coordinate corresponding to the maximum or minimum value point of the vertical coordinate is confirmed as the first rotation position of the motor of the strapdown gyro north-seeking instrument to be calibrated.

[0009] The advantages and positive effects of the present invention are: 1. The strapdown gyro north finder rotation self-calibration method provided by the present invention is simple, convenient, time-saving, labor-saving and efficient. All four positions of the strapdown gyro north finder's north-seeking motor rotation can be obtained through one self-calibration. Each strapdown gyro north finder can complete self-calibration in only one hour without manual intervention. Multiple devices can also be calibrated simultaneously according to the size of the turntable, greatly improving the calibration efficiency.

[0010] 2. The present invention can also shorten the calibration time by modifying parameters such as the turntable speed, the traversal range and the step size during calibration of each motor position.

[0011] 3. The present invention is applicable to all multi-position north-finding strapdown gyro north-finders that adopt a motor rotation method, and is not limited to the four positions described in the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a reference diagram of a strapdown gyro north finder installed on a turntable according to an embodiment of the present invention; Figure 2 This is a diagram of the on-site installation of the strapdown north finder of the present invention on a turntable, in which five strapdown north finders are installed and calibrated simultaneously; Figure 3 This is a sinusoidal curve fitting effect diagram of the encoder value and gyroscope angular velocity data scatter points when the motor is rotated to the first position of north seeking during the self-calibration process of the embodiment of the present invention; Figure 4 This is a sinusoidal curve fitting effect diagram of the encoder value and gyroscope angular velocity data scatter points at the second position of the motor in the self-calibration process of the embodiment of the present invention; Figure 5 This is a sinusoidal curve fitting effect diagram of the encoder value and gyroscope angular velocity data scatter points at the third position when the motor is rotated to the north-seeking position during the self-calibration process of the embodiment of the present invention; Figure 6 This is a sinusoidal curve fitting effect diagram of the encoder value and the gyroscope angular velocity data scatter points at the fourth position when the motor is rotated to the north-seeking position during the self-calibration process of an embodiment of the present invention. DETAILED DESCRIPTION

[0013] The structure of the present invention will be further described below with reference to the accompanying drawings and through examples. It should be noted that the present examples are descriptive rather than restrictive.

[0014] A strapdown gyro north finder rotation self-calibration method is disclosed. The invention is as follows: all four rotation positions of the strapdown gyro north finder's motor are obtained through a self-calibration, including the following steps: Step 1: Fixing a strapdown gyro north finder on a turntable via its structural reference surface, wherein the heading axis of the strapdown gyro north finder is parallel to the outer frame axis of the turntable; Step 2: Control the motor of the strapdown gyro north finder to rotate to the first north-seeking position 0°; Step 3: Control the outer frame of the turntable to rotate at a constant speed of a° / s, and at the same time control the motor of the strapdown gyro north finder to rotate in sequence within the range of ±m° of the first north-seeking position 0° in steps of n°, and stay at the position after each rotation for t seconds to perform gyro data sampling of the strapdown gyro north finder; The value of a is preferably 20, the value of m is preferably 0.7, the value of n is preferably 0.05, and the value of t is preferably 18.

[0015] Step 4. After completing all the rotation sampling within the range of ±n° of the first position 0° of north-seeking, data scatter points are obtained, whose horizontal coordinates are the encoder value of the strapdown gyro north-seeking instrument and whose vertical coordinates are the gyro angular velocity of the strapdown gyro north-seeking instrument; then, a sine curve fitting is performed on the data scatter points to obtain the maximum or minimum value of the vertical coordinate of the sine curve within the range of ±n°, and the horizontal coordinate corresponding to the maximum or minimum value point of the vertical coordinate is confirmed as the first rotation position of the motor of the strapdown gyro north-seeking instrument to be calibrated.

[0016] Step 5: Control the motor of the strapdown gyro north finder to rotate to the second north-seeking position of 90°, the third position of 180°, and the fourth position of 270° in sequence. Repeat steps 3 and 4 at each position to obtain the second, third, and fourth positions of the north-seeking motor of the strapdown gyro north finder to be calibrated. All four positions of the north-seeking motor of the strapdown gyro north finder are obtained through one self-calibration.

[0017] Example: This embodiment takes the XB35-3C strapdown gyro north finder as an example. Figure 1 The strapdown gyro north finder consists of a gyro and motor (including an encoder) installed in a strapdown configuration. The gyro is mounted sideways on the horizontal rotating portion of the motor. The gyro north-finding function is utilized to achieve gyro north-finding. The north-finding result is outputted using the structural reference surface to establish a north reference.

[0018] The turntable used is a 902C-3 dual-axis position rate turntable. Five strapdown gyro north finders are fixed on the turntable according to the structural reference surface, ensuring that the heading axes of all strapdown gyro north finders are parallel to the turntable outer frame axis. Figure 2 Control the motors of all strapdown gyro north finders to rotate to the first north-seeking position of 0°, control the outer frame of the turntable to rotate at a constant speed of 20° / s, and at the same time control the motors of all strapdown gyro north finders to rotate in sequence within the range of ±0.7° of the first north-seeking position of 0° in 0.05° steps. Stay at the position after each rotation for 18 seconds and sample the gyros of all strapdown gyro north finders. After completing all rotation sampling within the range of ±0.7° of the first north-seeking position of 0°, obtain data scatter points with the horizontal coordinate being the encoder value of the strapdown gyro north finder and the vertical coordinate being the gyro angular velocity of the strapdown gyro north finder. Perform sinusoidal curve fitting on these data scatter points to obtain the maximum or minimum value of the vertical coordinate of the sine curve within the range of ±0.7°. The horizontal coordinate corresponding to the maximum or minimum value point of the vertical coordinate is the first rotation position of the strapdown gyro north finder north-seeking motor to be calibrated, see Figure 3 ; Control the motors of all strapdown gyro north finders to rotate to the second north-seeking position of 90° (see Figure 4 ), the third position 180° (see Figure 5), the fourth position 270° (see Figure 6 Repeat the above steps to obtain the second, third, and fourth north-seeking motor positions for all strapdown gyro north-finders to be calibrated. Finally, after a single self-calibration, all four north-seeking motor positions are obtained for all strapdown gyro north-finders. After all strapdown gyro north-finders have completed self-calibration, a north-seeking verification test is performed simultaneously on a turntable.

[0019] The relevant record charts of the self-calibration of device X in this embodiment are as follows: the four rotation positions of the motor obtained by self-calibration are shown in Table 1, and the sine curve fitting effect of the encoder value and the gyroscope angular velocity data scatter points at the four rotation positions of the motor during the self-calibration process is shown in Table 1. Figure 2 The north-seeking verification test results after self-calibration are shown in Table 2.

[0020] Table 1 Four indexing positions of the motor after self-calibration of equipment No. X

[0021] Table 2 North-seeking verification test results after self-calibration of device X

[0022] Although the embodiments and drawings of the present invention are disclosed for illustrative purposes, those skilled in the art will understand that various replacements, changes and modifications are possible without departing from the spirit of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims

1. A strapdown gyro north finder rotation self-calibration method, characterized by: The strapdown gyro north finder's north-seeking motor indexing position is obtained through a self-calibration, including the following steps: Step 1: Fixing a strapdown gyro north finder on a turntable via its structural reference surface, wherein the heading axis of the strapdown gyro north finder is parallel to the outer frame axis of the turntable; Step 2: Control the motor of the strapdown gyro north finder to rotate to the first north-seeking position 0°; Step 3: Control the outer frame of the turntable to rotate at a constant speed of a° / s, and at the same time control the motor of the strapdown gyro north finder to rotate in sequence within the range of ±m° of the first north-seeking position 0° in steps of n°, and stay at the position after each rotation for t seconds to perform gyro data sampling of the strapdown gyro north finder; Step 4: Process the sampled data of step 3 to obtain the first position of the north-seeking motor of the strapdown gyro north-seeker; Step 5: Control the motor of the strapdown gyro north finder to rotate to the second north-seeking position of 90°, the third position of 180°, and the fourth position of 270° in sequence. Repeat steps 3 and 4 at each position to obtain the second, third, and fourth positions of the north-seeking motor of the strapdown gyro north finder to be calibrated. All four positions of the north-seeking motor of the strapdown gyro north finder are obtained through one self-calibration.

2. The strapdown gyro north finder rotation self-calibration method according to claim 1, characterized in that: In step 3, a is set to 20, m is set to 0.7, n is set to 0.05, and t is set to 18.

3. The strapdown gyro north finder rotation self-calibration method according to claim 1, characterized in that: Step 4 specifically includes: after completing all the rotation sampling within the range of ±n° of the first position 0° of the north-seeking, obtaining data scatter points whose horizontal coordinates are the encoder values ​​of the strapdown gyro north-seeking instrument and whose vertical coordinates are the gyro angular velocity of the strapdown gyro north-seeking instrument; then performing sinusoidal curve fitting on the data scatter points to obtain the maximum or minimum value of the vertical coordinate of the sine curve within the range of ±n°, and the horizontal coordinate corresponding to the maximum or minimum value point of the vertical coordinate is confirmed as the first rotation position of the motor of the strapdown gyro north-seeking instrument to be calibrated.

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