A method, device and storage medium for calibrating IMU heading installation deviation angle

Abstract

The present invention discloses a calibration method, device and storage medium for the heading installation deviation angle of an IMU, and relates to the technical field of attitude angle error calibration. The key points of the technical solution are as follows: the method comprises the following steps: obtaining the accelerometer data of the IMU; making a calibration state judgment based on the accelerometer data of the IMU, and recording the calibration state data, wherein the calibration state data record comprises a static initial state data record, a dynamic motion state data record and a static final state data record; making a carrier motion axial judgment based on the initial state data record and the final state data record, and obtaining a carrier uniaxial motion direction; using the conversion formula of the accelerometer, and combining the carrier uniaxial motion direction, to calculate the heading installation deviation angle between the IMU and the carrier. The present invention greatly simplifies the calibration process, reduces the calibration steps, improves the operating efficiency, and has the advantages of a wide range of adaptation and strong operability.

Description

Technical Field

[0001] The present invention relates to the technical field of attitude angle error calibration, and more specifically, to a calibration method, device and storage medium for an IMU heading installation deviation angle. Background Art

[0002] In the field of engineering machinery, IMU is widely used to measure the roll and pitch angles of the carrier. However, due to the inevitable installation errors during the manual installation process, the roll and pitch angles of the carrier calculated based on the IMU will be coupled with each other, resulting in reduced measurement accuracy. In order to improve the measurement accuracy, the installation deviation angle of the IMU needs to be calibrated.

[0003] In the prior art, a Chinese patent with the authorization announcement number CN104121926B discloses a calibration method for the installation error angle between the rotating axis and the sensitive axis of a dual-axis rotating inertial navigation system. The key points of the technical solution are: calibrate the four installation error angles of ΔθM1, ΔγM1, ΔψM2 and ΔγM2, and then compensate them to complete the demodulation of the dual-axis rotating inertial navigation. The specific steps are as follows: Step 1: Calibration and compensation of the inner ring error angles ΔθM1 and ΔγM1; Step 2: Calibration and compensation of the inner ring error angles ΔψM2 and ΔγM2. This solution divides the installation error angles of the IMU and the transposition mechanism into two groups of inner ring error angles and calibrates them separately in two steps. In both calibration steps, the navigation results and the angle output values ​​of the transposition mechanism need to be used. There are problems such as complicated definition of error angles, complicated calibration process, and calibration accuracy depending on navigation results and the output values ​​of the transposition mechanism. For example, Chinese patent publication number CN115265591A discloses a method for calibrating the installation error of a dual-axis rotating inertial navigation IMU and a transfer mechanism. This solution is still affected by the gyro accuracy of the IMU and the turntable rate accuracy. The calibration accuracy is still not high, the scope of use is limited, and the equipment cost is high.

[0004] Therefore, a new solution needs to be proposed to solve this problem. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a calibration method, device and storage medium for the IMU heading installation deviation angle, which greatly simplifies the calibration process, reduces the calibration steps, improves operational efficiency, and has the advantages of a wide adaptability range and strong operability.

[0006] The above technical purpose of the present invention is achieved through the following technical solution: A method for calibrating an IMU heading installation deviation angle comprises the following steps:

[0007] Get the accelerometer data of IMU;

[0008] Calibration state judgment is performed based on the accelerometer data of the IMU, and calibration state data is recorded, wherein the calibration state data record includes a static initial state data record, a dynamic motion state data record, and a static final state data record;

[0009] Based on the initial state data record and the final state data record, the carrier movement axis is judged to obtain a single axial movement direction of the carrier;

[0010] The heading installation deviation angle between the IMU and the carrier is calculated by using the conversion formula of the accelerometer and combining the uniaxial motion direction of the carrier.

[0011] In one embodiment, the initial state data recording, motion state data recording and final state data recording are performed sequentially.

[0012] In one embodiment, the calibration state judgment includes dynamic and static judgments, and the dynamic and static judgment methods are as follows:

[0013] Cache the accelerometer data of the IMU to a target time period, and collect the measurement data of the accelerometer of the IMU in three axes during the cache time period, wherein the three axes are respectively an x-axis, a y-axis, and a z-axis;

[0014] For the measurement data of each IMU accelerometer in the three axes within the target time period, calculate its STD value respectively;

[0015] The calculated STD values ​​of the three axes are compared with the preset thresholds respectively. If the STD value exceeds the preset threshold, it is judged as dynamic; if the STD value is less than the preset threshold, it is judged as static;

[0016] The formula for calculating the STD value is:

[0017]

[0018] Wherein, STD is the standard deviation, x is the measurement data of the IMU accelerometer in any one of the three axes, and x i represents the i-th measurement data, represents the average value of all measurement data sets, and N represents the number of samples of measurement data.

[0019] In one embodiment, when the calibration state data is recorded as the initial state data, the accelerometer data of the IMU is saved, and the roll angle and the pitch angle are calculated based on the accelerometer data. The calculation formulas of the roll angle and the pitch angle are as follows:

[0020]

[0021] Among them, Roll is the roll angle, Pitch is the pitch angle, acc x ,acc y and acc z It is the measurement data of the IMU's accelerometer in the three axes of x, y and z.

[0022] In one of the embodiments, when the calibration state data is recorded as motion state data, if the current IMU has gyroscope data, the gyroscope data is recorded; if the gyroscope data does not exist, the gyroscope data is not recorded.

[0023] In one embodiment, the roll angle and pitch angle of the accelerometer data of the IMU in the final state data recording are calculated in the same manner as in the initial state data recording.

[0024] In one embodiment, the specific method of determining the carrier movement axis based on the initial state data record and the final state data record to obtain a single-axis movement direction of the carrier is:

[0025] Subtract the Roll data recorded in the initial state data from the Roll data recorded in the final state data to obtain the Roll difference ΔRoll;

[0026] Subtract the Pitch data recorded in the initial state data from the Pitch data recorded in the final state data to obtain the Pitch difference ΔPitch;

[0027] The carrier movement axis is determined by comparing the values ​​of ΔRoll and ΔPitch, and the angle with the larger difference corresponds to the uniaxial movement direction.

[0028] In one embodiment, the conversion formula of the accelerometer is:

[0029]

[0030] Among them, yaw represents the heading installation deviation angle, a bx 、a by 、a bz They are the accelerometer values ​​in the x, y, and z axes in the IMU's own coordinate system, respectively. nx 、a ny 、a nz They are the accelerometer values ​​in the x, y and z axes in the carrier coordinate system respectively;

[0031] The specific method of using the conversion formula of the accelerometer and combining the uniaxial motion direction to calculate the heading installation deviation angle between the IMU and the carrier is:

[0032] Since the carrier moves in a single axis, only one angle in the carrier coordinate system changes, and another formula is derived based on the calculation formulas of the roll angle and the pitch angle and the conversion formula of the accelerometer. The other formula is:

[0033]

[0034] The formula describes the relationship that when one of the angles of the carrier in Roll and Pitch moves, the attitude angle of the other angle remains unchanged. They are the measurement data of the initial state data record and the final state data record in the three axes of the IMU accelerometer x, y and z, and these measurement data are all known quantities;

[0035] Since the accelerometer data of the IMU is a known quantity, and the heading installation deviation angle is the only unknown quantity, the heading installation deviation angle can be obtained using the ergodic method.

[0036] A device for calibrating an IMU heading installation deviation angle, comprising:

[0037] A data acquisition module, specifically an IMU module, configured to acquire accelerometer data of the IMU;

[0038] A calibration state judgment module is configured to perform calibration state judgment based on the accelerometer data of the IMU and to record calibration state data, wherein the calibration state data record includes a static initial state data record, a dynamic motion state data record, and a static final state data record;

[0039] A motion axis determination module is configured to determine the motion axis of the carrier based on the initial state data record and the final state data record to obtain a single-axis motion direction of the carrier;

[0040] The heading installation deviation angle calculation module is configured to calculate the heading installation deviation angle between the IMU and the carrier by using the conversion formula of the accelerometer and combining the uniaxial motion direction of the carrier.

[0041] A machine-readable storage medium includes an IMU heading installation deviation angle calibration method program. When the IMU heading installation deviation angle calibration method program is executed by a processor, any of the IMU heading installation deviation angle calibration methods described above is implemented.

[0042] In summary, the present invention has the following beneficial effects: compared with the prior art, the calibration method of the heading installation deviation angle of the present invention avoids the process of dividing the installation error angles of the IMU and the carrier into multiple groups for complex calibration, and directly obtains the accelerometer data of the IMU for calibration state judgment and recording, and performs carrier motion axis judgment through initial state data recording and final state data recording. The method can accurately identify the uniaxial motion direction of the carrier, and combined with the conversion formula of the uniaxial motion direction of the carrier and the accelerometer, it can accurately calculate the heading installation deviation angle between the IMU and the carrier, greatly simplifies the calibration process, reduces the calibration steps, and improves operating efficiency. The method has low requirements on the motion accuracy of the carrier, has good adaptability, low equipment cost, and a wide range of applications. It can maintain high measurement accuracy under various installation conditions. At the same time, the method uses the relationship based on the existence of an invariant in the attitude angle during unidirectional axis motion to solve the heading installation deviation angle, and has the advantage of strong operability. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 A flowchart of a method for calibrating an IMU heading installation deviation angle according to an embodiment of the present application;

[0044] Figure 2 This is a structural block diagram of a device for calibrating an IMU heading installation deviation angle according to an embodiment of the present application.

[0045] In the figure: 2. IMU heading installation deviation angle calibration device; 21. Data acquisition module; 22. Calibration state judgment module; 23. Movement axis judgment module; 24. Heading installation deviation angle calculation module. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] like Figure 1 and Figure 2 As shown, an embodiment of the present application provides a method for calibrating an IMU heading installation deviation angle. The method is applicable to carriers such as excavators and turntables that can ensure uniaxial motion, and includes the following steps:

[0048] In step S1, the accelerometer data of the IMU (inertial measurement unit) is obtained. Specifically, the velocity data of the carrier is obtained through the accelerometer of the IMU, and these data are input and provided to the subsequent steps. In this embodiment, the IMU can be a three-axis module composed of a three-axis accelerometer, a six-axis IMU module composed of a three-axis angular velocity and a three-axis accelerometer, or a nine-axis IMU module composed of a three-axis accelerometer, a three-axis angular velocity and a three-axis magnetometer. As long as there is a three-axis accelerometer, the requirements of the technical solution can be met;

[0049] In step S2, a calibration state judgment is performed based on the accelerometer data of the IMU, and calibration state data is recorded, wherein the calibration state data record includes a static initial state data record, a dynamic motion state data record, and a static final state data record;

[0050] In step S3, the carrier movement axial direction is judged based on the initial state data record and the final state data record to obtain a single axial movement direction of the carrier;

[0051] In step S4, the heading installation deviation angle between the IMU and the carrier is calculated by using the conversion formula of the accelerometer and combining the uniaxial motion direction of the carrier.

[0052] Compared with the prior art, the calibration method of the heading installation deviation angle of the present invention avoids the process of dividing the installation error angles of the IMU and the carrier into multiple groups for complex calibration. The calibration state is judged and recorded by directly acquiring the accelerometer data of the IMU, and the axial motion of the carrier is judged by the initial state data record and the final state data record. The method can accurately identify the uniaxial motion direction of the carrier, and combine the conversion formula of the uniaxial motion direction of the carrier and the accelerometer to accurately calculate the heading installation deviation angle between the IMU and the carrier, which greatly simplifies the calibration process, reduces the calibration steps, and improves the operating efficiency. In addition, the method has low requirements on the motion accuracy of the carrier, has good adaptability, low equipment cost, and a wide range of applications. High measurement accuracy can be maintained under various installation conditions.

[0053] In this embodiment, the initial state data recording, motion state data recording and final state data recording are performed in sequence. Recording data in sequence can ensure that the IMU data is recorded completely and orderly in the entire process from static to dynamic and then to static, which not only improves the calibration accuracy and efficiency of the IMU heading installation deviation angle, but also enhances the reliability and applicability of the calibration results.

[0054] In this embodiment, the calibration state judgment includes dynamic and static judgments, and the dynamic and static judgment methods are as follows:

[0055] Cache the accelerometer data of the IMU to a target time period, and collect the measurement data of the accelerometer of the IMU in three axes during the cache time period, wherein the three axes are respectively an x-axis, a y-axis, and a z-axis;

[0056] For the measurement data of each IMU accelerometer in the three axes within the target time period, calculate its STD value, i.e. standard deviation value;

[0057] The calculated STD values ​​of the three axes are compared with the preset thresholds respectively. If the three STD values ​​exceed the preset thresholds, it is judged as dynamic. If the three STD values ​​are less than the preset thresholds, it is judged as static.

[0058] The formula for calculating the STD value is:

[0059]

[0060] Wherein, STD is the standard deviation, x is the measurement data of the IMU accelerometer in any one of the three axes, and x i represents the i-th measurement data, represents the average value of all measurement data sets, and N represents the number of samples of measurement data.

[0061] In this embodiment, when the calibration state data is recorded as the initial state data, the accelerometer data of the IMU is saved, and the roll angle and the pitch angle are calculated based on the accelerometer data. The calculation formulas of the roll angle and the pitch angle are as follows:

[0062]

[0063] Among them, Roll is the roll angle, Pitch is the pitch angle, acc x ,acc y and acc z It is the measurement data of the IMU's accelerometer in the three axes of x, y and z.

[0064] In the above method, roll angle and pitch angle are important parameters to describe the carrier's attitude. By accurately calculating these two angles, the carrier's attitude can be accurately estimated. The accelerometer data is recorded in the initial state and directly used to calculate the roll angle and pitch angle, which simplifies the IMU calibration process. Compared with traditional calibration methods, this method reduces the dependence on calibration equipment and environment, reduces calibration costs, and improves calibration efficiency.

[0065] In this embodiment, when the calibration state data is recorded as motion state data, if the current IMU has gyroscope data, the gyroscope data is recorded; if the gyroscope data does not exist, the gyroscope data is not recorded.

[0066] In the above method, the gyroscope is optional. For IMUs equipped with gyroscopes, recording gyroscope data in motion can provide more comprehensive motion information. For IMUs not equipped with gyroscopes, not recording gyroscope data can avoid unnecessary waste of resources. This includes storage space, processing time, and possible energy consumption. By only recording available and necessary data, resource usage can be optimized and the overall efficiency of the system can be improved.

[0067] In this embodiment, the roll angle and pitch angle of the accelerometer data of the IMU when recording the final state data are calculated in the same manner as in the initial state data recording.

[0068] In this embodiment, the specific method of determining the carrier movement axis based on the initial state data record and the final state data record to obtain a single-axis movement direction of the carrier is:

[0069] Subtract the Roll data recorded in the initial state data from the Roll data recorded in the final state data to obtain the Roll difference ΔRoll;

[0070] Subtract the Pitch data recorded in the initial state data from the Pitch data recorded in the final state data to obtain the Pitch difference ΔPitch;

[0071] The carrier movement axis is determined by comparing the size of ΔRoll and ΔPitch, and the angle with the larger difference corresponds to the uniaxial movement direction. For example, if ΔRoll is much larger than ΔPitch, it can be considered that the carrier mainly rotates around the x-axis, so the movement axis is the X-axis; if Pitch is much larger than ΔRollΔ, it can be considered that the carrier mainly rotates around the y-axis, so the movement axis is the y-axis; it should be noted that if the carrier rotates around the Z-axis, then the changes in ΔRoll and ΔPitch should be very small, because the rotation of the z-axis will not directly cause changes in Roll and Pitch. Roll corresponds to the x-axis, Pitch corresponds to the y-axis, and the Z-axis represents the vertical axis (yaw axis), and vertically upward is positive.

[0072] In this embodiment, the conversion formula of the accelerometer is:

[0073]

[0074] Among them, yaw represents the heading installation deviation angle, a bx 、a by 、a bz They are the accelerometer values ​​in the x, y, and z axes in the IMU's own coordinate system, respectively. nx 、a ny 、a nzThey are the accelerometer values ​​in the x, y and z axes in the carrier coordinate system respectively;

[0075] The specific method of using the conversion formula of the accelerometer and combining the uniaxial motion direction to calculate the heading installation deviation angle between the IMU and the carrier is:

[0076] Since the carrier moves in a single axis, only one angle in the carrier coordinate system changes, and another formula is derived based on the calculation formulas of the roll angle and the pitch angle and the conversion formula of the accelerometer. The other formula is:

[0077]

[0078] The formula describes the relationship that when one of the angles of the carrier in Roll and Pitch moves, the attitude angle of the other angle remains unchanged. are the accelerometer data of IMU, and they are all known quantities;

[0079] Since the accelerometer data of the IMU is a known quantity, and the heading installation deviation angle is the only unknown quantity, the heading installation deviation angle can be obtained using the traversal method. The specific method is: traverse the yaw angle (heading installation deviation angle) within the range of positive and negative 180 degrees, and substitute it into the other formula for calculation. By comparing the residuals of the angle values ​​calculated in the initial state and the final state, find the yaw angle value with the smallest residual, which is the installation deviation angle.

[0080] In the above method, the heading installation deviation angle is solved by utilizing the relationship that the attitude angle exists as an invariant when the unidirectional axis moves, which has the advantage of strong operability.

[0081] The present invention also discloses a calibration device 2 for an IMU heading installation deviation angle, comprising:

[0082] A data acquisition module 21 is configured to acquire accelerometer data of the IMU;

[0083] The calibration state judgment module 22 is configured to perform calibration state judgment based on the accelerometer data of the IMU and record calibration state data, wherein the calibration state data record includes a static initial state data record, a dynamic motion state data record, and a static final state data record;

[0084] A motion axis determination module 23 is configured to determine the motion axis of the carrier based on the initial state data record and the final state data record to obtain a single-axis motion direction of the carrier;

[0085] The heading installation deviation angle calculation module 24 is configured to calculate the heading installation deviation angle between the IMU and the carrier by using the conversion formula of the accelerometer and combining the uniaxial motion direction of the carrier.

[0086] Optionally, if gyroscope data exists, after calculating the yaw angle, the integral value of the gyroscope angular velocity can be substituted into the conversion formula of the accelerometer to calculate the residual value of the non-rotation angle. If the residual value is less than the set threshold, it is considered to meet the requirements. If the residual value is greater than the threshold, it may be necessary to recalibrate the heading installation deviation angle. Of course, this step can also be ignored according to actual conditions.

[0087] The present invention also discloses a machine-readable storage medium, which includes a calibration method program for an IMU heading installation deviation angle. When the calibration method program for the IMU heading installation deviation angle is executed by a processor, any of the calibration methods for the IMU heading installation deviation angle is implemented.

[0088] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A method for calibrating an IMU heading installation deviation angle, characterized in that: The steps include: Get the accelerometer data of IMU; Calibration state judgment is performed based on the accelerometer data of the IMU, and calibration state data is recorded, wherein the calibration state data record includes a static initial state data record, a dynamic motion state data record, and a static final state data record; Based on the initial state data record and the final state data record, the carrier movement axis is judged to obtain a single axial movement direction of the carrier; The heading installation deviation angle between the IMU and the carrier is calculated by using the conversion formula of the accelerometer and combining the uniaxial motion direction of the carrier.

2. The method for calibrating the IMU heading installation deviation angle according to claim 1, characterized in that: The initial state data recording, motion state data recording and final state data recording are executed in sequence.

3. The method for calibrating the IMU heading installation deviation angle according to claim 1, characterized in that: The calibration state judgment includes dynamic and static judgment, and the dynamic and static judgment methods are as follows: Cache the accelerometer data of the IMU to a target time period, and collect the measurement data of the accelerometer of the IMU in three axes during the cache time period, wherein the three axes are respectively an x-axis, a y-axis, and a z-axis; For the measurement data of each IMU accelerometer in the three axes within the target time period, calculate its STD value respectively; The calculated STD values ​​of the three axes are compared with the preset thresholds respectively. If the STD value exceeds the preset threshold, it is judged as dynamic; if the STD value is less than the preset threshold, it is judged as static; The formula for calculating the STD value is: Wherein, STD is the standard deviation, x is the measurement data of the IMU accelerometer in any one of the three axes, and x i represents the i-th measurement data, represents the average value of all measurement data sets, and N represents the number of samples of measurement data.

4. The method for calibrating the IMU heading installation deviation angle according to claim 3, characterized in that: When the calibration state data record is the initial state data record, the accelerometer data of the IMU is saved, and the roll angle and the pitch angle are calculated based on the accelerometer data. The calculation formulas of the roll angle and the pitch angle are as follows: Among them, Roll is the roll angle, Pitch is the pitch angle, acc x ,acc y and acc z It is the measurement data of the IMU's accelerometer in the three axes of x, y and z.

5. The method for calibrating the IMU heading installation deviation angle according to claim 3, characterized in that: When the calibration state data is recorded as motion state data, if the current IMU has gyroscope data, the gyroscope data is recorded; if the gyroscope data does not exist, the gyroscope data is not recorded.

6. The method for calibrating the IMU heading installation deviation angle according to claim 4, characterized in that: The roll and pitch angles of the IMU accelerometer data for the final state data recording are calculated in the same manner as for the initial state data recording.

7. The method for calibrating the IMU heading installation deviation angle according to claim 6, characterized in that: The specific method of determining the carrier movement axis based on the initial state data record and the final state data record to obtain a single axial movement direction of the carrier is: Subtract the Roll data recorded in the initial state data from the Roll data recorded in the final state data to obtain the Roll difference ΔRoll; Subtract the Pitch data recorded in the initial state data from the Pitch data recorded in the final state data to obtain the Pitch difference ΔPitch; The carrier movement axis is determined by comparing the values ​​of ΔRoll and ΔPitch, and the angle with the larger difference corresponds to the uniaxial movement direction.

8. The method for calibrating the IMU heading installation deviation angle according to claim 5, characterized in that: The conversion formula of the accelerometer is: Among them, yaw represents the heading installation deviation angle, a bx 、a by 、a bz They are the accelerometer values ​​in the x, y, and z axes in the IMU's own coordinate system, respectively. nx 、a ny 、a nz They are the accelerometer values ​​in the x, y, and z axes in the carrier coordinate system; The specific method of using the conversion formula of the accelerometer and combining the uniaxial motion direction to calculate the heading installation deviation angle between the IMU and the carrier is: Since the carrier moves in a single axis, only one angle in the carrier coordinate system changes, and another formula is derived based on the calculation formulas of the roll angle and the pitch angle and the conversion formula of the accelerometer. The other formula is: The formula describes the relationship that when one of the angles of the carrier in Roll and Pitch moves, the attitude angle of the other angle remains unchanged. They are the measurement data of the initial state data record and the final state data record in the three axes of the IMU accelerometer x, y and z, and these measurement data are all known quantities; Since the accelerometer data of the IMU is a known quantity, and the heading installation deviation angle is the only unknown quantity, the heading installation deviation angle can be obtained using the ergodic method.

9. A calibration device for an IMU heading installation deviation angle, characterized in that: include: A data acquisition module configured to acquire accelerometer data of the IMU; A calibration state judgment module is configured to perform calibration state judgment based on the accelerometer data of the IMU and to record calibration state data, wherein the calibration state data record includes a static initial state data record, a dynamic motion state data record, and a static final state data record; A motion axis determination module is configured to determine the motion axis of the carrier based on the initial state data record and the final state data record to obtain a single-axis motion direction of the carrier; The heading installation deviation angle calculation module is configured to calculate the heading installation deviation angle between the IMU and the carrier by using the conversion formula of the accelerometer and combining the uniaxial motion direction of the carrier.

10. A machine-readable storage medium, characterized in that: The machine-readable storage medium includes a calibration method program for the IMU heading installation deviation angle. When the calibration method program for the IMU heading installation deviation angle is executed by a processor, the calibration method for the IMU heading installation deviation angle as described in any one of claims 1-8 is implemented.

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