A calibration system and calibration method for an inertial measurement unit

Abstract

The present invention relates to the field of data processing technology, and in particular to a calibration system and calibration method for an inertial measurement unit. The system comprises: a setting module first determines a number of key points of a test aircraft, and arranges a number of inertial measurement units accordingly. A data acquisition module collects the real-time acceleration of the inertial measurement unit at a preset frequency. A comparison module compares the real-time acceleration of each unit, determines a first acceleration range based on the result, and then determines a first calibration parameter, or adjusts the frequency and issues a secondary judgment instruction. After receiving the instruction, the route judgment module draws a real-time route map based on the real-time acceleration, compares the preset route map to determine the second calibration parameter, and adjusts the first acceleration range or issues a tertiary judgment instruction when necessary. After receiving the instruction, the temperature judgment module collects the real-time temperature value, draws a curve and analyzes it to determine the third calibration parameter. The calibration module uses the above parameters in combination to calibrate the inertial measurement unit. The present invention improves the measurement accuracy of the inertial measurement unit.

Description

Technical Field

[0001] The present invention relates to the technical field of data processing, and in particular to a calibration system and a calibration method for an inertial measurement unit. Background Art

[0002] An inertial measurement unit (IMU) is a device that integrates multiple sensors, mainly accelerometers, gyroscopes, and sometimes magnetometers. Accelerometers are used to measure the linear acceleration of an object, gyroscopes are used to measure the angular velocity of an object, and magnetometers are used to measure the direction of the Earth's magnetic field. These sensors work together to measure the motion state of an object and transmit the data to related systems for processing.

[0003] A patent document with Chinese patent application publication number CN115790664A discloses an inertial measurement unit calibration system, including: a deformation detection module, which is configured to detect the deformation amount of a circuit board equipped with an inertial measurement unit; and a control module, which is respectively communicated with the deformation detection module and the inertial measurement unit; which is configured to: call the default output of the inertial measurement unit under a set test state, and obtain the detected deformation amount output by the deformation detection module under the set test state and the actual measurement output of the inertial measurement unit corresponding to the detected deformation amount; the control module uses the actual measurement output to calibrate the default output to a first calibration output and establish a one-to-one correspondence between the calibration amount and the detected deformation amount.

[0004] The prior art only considers the influence of the circuit board deformation factor on the output of the inertial measurement unit, resulting in insufficient comprehensiveness of the calibration and difficulty in ensuring that a high-precision calibration effect can be achieved under various complex working conditions. Summary of the invention

[0005] To this end, the present invention provides a calibration system and a calibration method for an inertial measurement unit, which can solve the problem of measurement deviation in the measurement process of the calibration measurement unit.

[0006] To achieve the above object, the present invention provides a calibration system for an inertial measurement unit, comprising:

[0007] A setting module is used to determine a number of key points of the test aircraft, and to set a number of inertial measurement units on the test aircraft based on the key points;

[0008] A data acquisition module, connected to the setting module, for acquiring a number of real-time accelerations obtained by any of the inertial measurement units based on a preset frequency;

[0009] a comparison module connected to the data acquisition module, for comparing a plurality of real-time accelerations acquired by the inertial measurement units, determining a first acceleration range based on the comparison result, determining a first calibration parameter according to the comparison result between the plurality of real-time accelerations and the first acceleration range, or adjusting a preset frequency, or issuing a secondary judgment instruction;

[0010] a route determination module, connected to the comparison module, for receiving a secondary determination instruction, drawing a real-time route map based on any one of the real-time accelerations, determining a second calibration parameter based on a comparison result between the real-time route map and a preset route map, or adjusting a first acceleration range, or issuing a tertiary determination instruction;

[0011] a temperature judgment module, connected to the route judgment module, for receiving three judgment instructions, collecting real-time temperature values ​​at the corresponding moments of a plurality of real-time accelerations in real time, drawing a temperature change curve based on the plurality of real-time temperature values, analyzing the temperature change curve, and determining a third calibration parameter according to the analysis result;

[0012] The calibration module is used to calibrate the measurement data of the inertial measurement unit based on the first calibration parameter, the second calibration parameter and / or the third calibration parameter to obtain calibration data.

[0013] Furthermore, the setting module includes:

[0014] A structure determination unit is used to perform flight simulation on the test aircraft, determine stress and strain distribution, and determine several key points based on the stress and strain distribution results;

[0015] The setting unit is connected to the structure determination unit and is used to set inertial measurement units at several of the key points.

[0016] Furthermore, the comparison module comprises:

[0017] A calculation unit, used for performing time synchronization processing on the plurality of real-time accelerations based on the acquisition timestamp, and calculating statistical characteristic values ​​corresponding to any plurality of the inertial measurement units;

[0018] a range determination unit, connected to the calculation unit, for performing clustering based on a plurality of the statistical characteristic values ​​to determine a first acceleration range;

[0019] The acceleration comparison unit is connected to the range determination unit and is used to determine the first calibration parameter according to the comparison results of the real-time accelerations and the first acceleration range, or to adjust the preset frequency, or to issue a secondary determination instruction.

[0020] Furthermore, the calculation unit comprises:

[0021] A time synchronization subunit, used to determine a time difference based on a preset timestamp and an acquisition timestamp, and to perform time synchronization processing on the plurality of real-time accelerations based on the time difference and a data interpolation algorithm;

[0022] The feature calculation subunit is connected to the time synchronization subunit and is used to calculate the actual mean feature, actual variance feature and actual covariance matrix feature corresponding to a plurality of the real-time acceleration values ​​within a preset time window.

[0023] Furthermore, the acceleration comparison unit comprises:

[0024] a first calculation subunit, configured to calculate an actual proportion of a plurality of real-time accelerations that are not within a first acceleration range, compare the actual proportion with a first preset proportion, and when the actual proportion is greater than or equal to the first preset proportion, calculate a regression coefficient based on the plurality of abnormal real-time accelerations as the first calibration parameter;

[0025] a frequency adjustment subunit, connected to the first calculation subunit, for adjusting the preset frequency when the actual proportion is less than the first preset proportion and greater than the second preset proportion;

[0026] The instruction generation subunit is connected to the frequency adjustment subunit, and is used to generate a secondary judgment instruction when the actual proportion is less than the second preset proportion.

[0027] Furthermore, the route determination module includes:

[0028] A route drawing unit, used for receiving the secondary judgment instruction and drawing a real-time route map based on the initial position and the real-time accelerations;

[0029] A route comparison unit is connected to the route drawing unit, and is used to calculate the trajectory similarity between the real-time route map and the preset route map, determine the second calibration parameter based on the comparison results of the trajectory similarity with the first preset similarity and the second preset similarity, or adjust the first acceleration range, or issue three judgment instructions.

[0030] Furthermore, the route drawing unit includes:

[0031] A trajectory calculation subunit, used to construct a plurality of flight trajectory point sequences based on a plurality of real-time acceleration data and initial position information;

[0032] The graphics drawing subunit is connected to the trajectory calculation subunit and is used to draw a real-time route map based on a plurality of flight trajectory point sequences.

[0033] Furthermore, the route comparison unit includes:

[0034] A similarity calculation subunit, used to calculate the similarity between the real-time route map and the preset route map based on a similarity algorithm;

[0035] The similarity comparison subunit is used to compare the actual similarity with the preset similarity. If the actual similarity is greater than or equal to the first preset similarity, three judgment instructions are generated. If the actual similarity is less than the first preset similarity and greater than or equal to the second preset similarity, the first acceleration range is adjusted. If the actual similarity is less than or equal to the second preset similarity, the second calibration parameter is determined.

[0036] Furthermore, the temperature judgment module includes:

[0037] The temperature collection unit is used to receive three judgment instructions and collect several real-time temperature values;

[0038] A curve analysis unit connected to the temperature acquisition unit is used to draw a temperature change curve based on a number of real-time temperature values, analyze the change trend and degree of the temperature change curve, and determine whether there is an abnormality in the temperature change according to the analysis result;

[0039] The calibration parameter determination unit is used to determine a third calibration parameter according to the analysis result of the temperature variation curve.

[0040] On the other hand, the present invention also provides a calibration method for a calibration system of an inertial measurement unit, comprising:

[0041] Determine a number of key points of the test aircraft, and set a number of inertial measurement units on the test aircraft based on the number of key points;

[0042] Collecting a plurality of real-time accelerations obtained by any of the inertial measurement units based on a preset frequency;

[0043] Comparing a plurality of real-time accelerations collected by the inertial measurement units, determining a first acceleration range based on the comparison result, determining a first calibration parameter according to the comparison result between the plurality of real-time accelerations and the first acceleration range, or adjusting a preset frequency, or issuing a secondary determination instruction;

[0044] Receiving a secondary judgment instruction, drawing a real-time route map based on any one of the real-time accelerations, determining a second calibration parameter based on a comparison result between the real-time route map and a preset route map, or adjusting the first acceleration range, or issuing a third judgment instruction;

[0045] receiving three judgment instructions, collecting real-time temperature values ​​at the moments corresponding to the real-time accelerations, drawing a temperature change curve based on the real-time temperature values, analyzing the temperature change curve, and determining a third calibration parameter according to the analysis result;

[0046] The measurement data of the inertial measurement unit is calibrated based on the first calibration parameter, the second calibration parameter and / or the third calibration parameter to obtain calibration data.

[0047] Compared with the prior art, the beneficial effect of the present invention lies in that, by setting the setting module, the inertial measurement units are accurately arranged at key positions according to the force characteristics of different parts of the aircraft, so that the collected acceleration data comprehensively and specifically reflects the actual motion state of the aircraft, avoiding data loss or inaccuracy caused by unreasonable measurement positions, and laying a foundation for subsequent precise calibration and accurate grasp of the flight conditions of the aircraft. By setting the data acquisition module to collect real-time acceleration according to a preset frequency, the data has regularity and consistency in the time dimension, which is convenient for subsequent unified processing and analysis of the data, and provides an accurate data basis for subsequent judgments. By setting the comparison module to compare the real-time accelerations collected by different inertial measurement units, the measurement deviations caused by installation errors, differences in their own performance, etc. between the units are accurately identified, and then the inertial measurement units with differences are targetedly calibrated based on the calibration parameters, effectively improving the accuracy of the calibration. The consistency of the measurement data of each unit is improved, so that the data output by the entire inertial measurement unit system is more reliable and stable, and the overall measurement accuracy is improved. By setting the route judgment module to draw a real-time route map based on the real-time acceleration and compare it with the preset route map, the deviation in the actual flight trajectory of the aircraft can be intuitively reflected, so as to determine the second calibration parameter to effectively correct its errors in navigation-related measurements, so that the navigation system of the aircraft can plan and adjust the flight route based on more accurate measurement data, thereby greatly improving the reliability and accuracy of the aircraft navigation system. By setting the temperature judgment module to determine the third calibration parameter for temperature compensation, the measurement deviation caused by temperature factors is effectively reduced, and the measurement stability and accuracy of the inertial measurement unit under different temperature conditions are improved. By setting the inertial measurement unit to be calibrated, comprehensive calibration optimization of the inertial measurement unit is achieved, ensuring that the inertial measurement unit outputs high-precision measurement data.

[0048] In particular, by setting the structure determination unit to perform flight simulation on the test aircraft, the stress and strain distribution can be determined, and those points on the aircraft structure that are sensitive to stress and strain and are subjected to complex and critical forces during flight can be accurately found, thereby providing accurate target position information for the subsequent reasonable layout of inertial measurement units. The determined key points can make the data collected by the inertial measurement units installed at these positions more representative, thereby improving the validity of the data of the entire inertial measurement system. By setting the setting unit, the scientific and reasonable layout of the inertial measurement units can be ensured, thereby improving the accuracy and comprehensiveness of the inertial measurement unit monitoring.

[0049] In particular, by setting the calculation unit to accurately align the data collected by different inertial measurement units at the same time, the comparability of the data is ensured, which lays a foundation for accurately evaluating the working status of each unit and discovering potential differences. The statistical characteristic value corresponding to any inertial measurement unit is calculated, and the acceleration data is quantitatively described from multiple dimensions, which is convenient for more comprehensive determination of the working characteristics of the inertial measurement unit, and provides rich data basis for subsequent precise calibration. By setting the range determination unit to determine the first acceleration range based on cluster analysis, it accurately reflects the reasonable acceleration value range under the current flight conditions and the performance state of the inertial measurement unit, and improves the accuracy of subsequent judgments on whether each unit is working normally and calibration work. By setting the acceleration comparison unit to determine the first calibration parameter, the deviation of each inertial measurement unit relative to the normal range can be accurately identified, and the calibration parameter can be calculated in a targeted manner for correction, thereby improving the measurement accuracy of the entire inertial measurement system, ensuring the accuracy of various control, navigation and other operations performed by the aircraft based on inertial measurement data, and improving the reliability of the entire inertial measurement unit calibration system. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 A structural block diagram of a calibration system for an inertial measurement unit provided in an embodiment of the present invention.

[0051] Figure 2 A structural block diagram of a setting module in a calibration system of an inertial measurement unit provided by an embodiment of the present invention;

[0052] Figure 3 A structural block diagram of a comparison module in a calibration system of an inertial measurement unit provided by an embodiment of the present invention;

[0053] Figure 4 A schematic flow chart of a calibration method for an inertial measurement unit provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0054] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0055] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0056] It should be noted that, in the description of the present invention, terms such as "up", "down", "left", "right", "inside" and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings. This is merely for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be understood as a limitation on the present invention.

[0057] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0058] See also Figure 1 As shown, an embodiment of the present invention provides a calibration system for an inertial measurement unit, the system comprising:

[0059] A setting module 10 is used to determine a number of key points of the test aircraft, and to set a number of inertial measurement units on the test aircraft based on the key points;

[0060] A data acquisition module 20, connected to the setting module 10, for acquiring a plurality of real-time accelerations obtained by any of the inertial measurement units based on a preset frequency;

[0061] A comparison module 30, connected to the data acquisition module 20, for comparing a plurality of real-time accelerations acquired by the inertial measurement units, determining a first acceleration range based on the comparison result, determining a first calibration parameter according to the comparison result between the plurality of real-time accelerations and the first acceleration range, or adjusting a preset frequency, or issuing a secondary judgment instruction;

[0062] A route judgment module 40, connected to the comparison module 30, for receiving a secondary judgment instruction, drawing a real-time route map based on any one of the real-time accelerations, determining a second calibration parameter based on a comparison result between the real-time route map and a preset route map, or adjusting a first acceleration range, or issuing a tertiary judgment instruction;

[0063] The temperature judgment module 50 is connected to the route judgment module 40, and is used to receive three judgment instructions, collect real-time temperature values ​​at the corresponding moments of a plurality of real-time accelerations, draw a temperature change curve based on the plurality of real-time temperature values, and analyze the temperature change curve to determine a third calibration parameter according to the analysis result;

[0064] The calibration module 60 is used to calibrate the measurement data of the inertial measurement unit based on the first calibration parameter, the second calibration parameter and / or the third calibration parameter to obtain calibration data.

[0065] Specifically, the embodiment of the present invention arranges the inertial measurement units accurately at key positions according to the force characteristics of different parts of the aircraft by setting the setting module, so that the collected acceleration data comprehensively and specifically reflects the actual motion state of the aircraft, avoids data loss or inaccuracy caused by unreasonable measurement positions, and lays a foundation for subsequent precise calibration and accurate grasp of the flight conditions of the aircraft. By setting the data acquisition module to collect real-time acceleration according to a preset frequency, the data has regularity and consistency in the time dimension, which is convenient for subsequent unified processing and analysis of the data, and provides an accurate data basis for subsequent judgments. By setting the comparison module to compare the real-time accelerations collected by different inertial measurement units, the measurement deviations caused by installation errors, differences in their own performance, etc. between the units are accurately identified, and then the inertial measurement units with differences are targeted for calibration based on the calibration parameters, effectively improving the calibration of each unit. The consistency of the measurement data makes the data output by the entire inertial measurement unit system more reliable and stable, and improves the overall measurement accuracy. By setting the route judgment module to draw a real-time route map based on real-time acceleration and compare it with the preset route map, the deviation in the actual flight trajectory of the aircraft can be intuitively reflected, so as to determine the second calibration parameter to effectively correct its errors in navigation-related measurements, so that the navigation system of the aircraft can plan and adjust the flight route based on more accurate measurement data, thereby greatly improving the reliability and accuracy of the aircraft navigation system. By setting the temperature judgment module to determine the third calibration parameter for temperature compensation, the measurement deviation caused by temperature factors is effectively reduced, and the measurement stability and accuracy of the inertial measurement unit under different temperature conditions are improved. By setting the inertial measurement unit to calibrate, comprehensive calibration optimization of the inertial measurement unit is achieved, ensuring that the inertial measurement unit outputs high-precision measurement data.

[0066] It can be understood that the preset frequency in the embodiment of the present invention is 5s / time.

[0067] See also Figure 2 As shown, the setting module 10 includes:

[0068] The structure determination unit 11 is used to perform flight simulation on the test aircraft, determine the stress and strain distribution, and determine a number of key points based on the stress and strain distribution results;

[0069] The setting unit 12 is connected to the structure determination unit 11 and is used to set inertial measurement units at some of the key points.

[0070] Specifically, the embodiment of the present invention sets the structure determination unit to perform flight simulation on the test aircraft to determine the stress and strain distribution, accurately find out those points on the aircraft structure that are sensitive to stress and strain and have complex and critical force conditions during flight, and provide accurate target position information for the subsequent reasonable layout of inertial measurement units. The determined key points can make the data collected by the inertial measurement units installed at these positions more representative, thereby improving the validity of the data of the entire inertial measurement system. By setting the setting unit, the scientific and reasonable layout of the inertial measurement units is ensured, and the accuracy and comprehensiveness of the inertial measurement unit monitoring are improved.

[0071] It can be understood that the structure determination unit in the embodiment of the present invention includes:

[0072] a distribution determination subunit, configured to simulate the test aircraft based on simulation software, obtain a number of simulated flow field pressure data, convert the plurality of simulated flow field pressure data into a load distribution acting on the aircraft structure, and determine the stress-strain distribution based on the load distribution;

[0073] The point determination subunit is connected to the distribution determination subunit, and is used to set the stress value range, compare a number of simulated stress values ​​corresponding to the stress-strain distribution with the stress value range, and determine the key points based on the comparison results, or calculate the stress mutation value, and compare the stress mutation value with the preset mutation value to determine the key points.

[0074] It can be understood that the simulation software described in the embodiment of the present invention is computational fluid dynamics (CFD) and structural mechanics coupling simulation software, such as a coupling module of ANSYS Fluent and ANSYS Mechanical.

[0075] It can be understood that the distribution determination subunit described in the embodiment of the present invention is used to simulate and analyze the flow field around the aircraft based on the computational fluid dynamics principle according to the simulation software, and calculate the flow field pressure data at various positions on the aircraft surface under different flight conditions by solving the basic fluid mechanics equations such as the Navier-Stokes equations. Then, the obtained simulated flow field pressure data is converted into concentrated forces and moments acting on the structural nodes through the equivalent principle of force, thereby constructing a load condition matching the finite element model of the aircraft structure, and the constructed load distribution is loaded onto the finite element model of the aircraft structure. The structural mechanics solver is used for solution calculation. The finite element model discretizes the aircraft structure into a large number of units (such as tetrahedral units, hexahedral units, etc.) and nodes, each unit having a specific material constitutive relationship and mechanical behavior. The displacement response of each unit node under different load conditions is obtained through solver calculation, and then the stress-strain distribution at various positions inside the aircraft structure is further calculated according to the stress-strain relationship of the material. The above process is a prior art and will not be repeated here.

[0076] It can be understood that the point determination subunit described in the embodiment of the present invention is used to determine the corresponding point as a key point when any simulated stress value is greater than the stress value range, and when any simulated stress value is within the stress value range, calculate the difference between the simulated stress value and the simulated stress values ​​corresponding to the surrounding points as the stress mutation value, and when the stress mutation value is greater than the preset mutation value, the point is used as the key point.

[0077] It can be understood that the stress value range described in the embodiment of the present invention is for small and light aircraft, such as some drones used for low-altitude and short-distance flights, whose structures are subjected to relatively small stresses. The upper limit of the stress value range may be set at around tens of MPa (e.g., 50MPa-100MPa), and the lower limit is usually set based on basic mechanical properties such as the yield strength and allowable stress of the material. Generally, a certain proportion of the yield strength of the material (e.g., 30% to 50%) is selected as the lower limit;

[0078] The preset mutation value is 10MPa.

[0079] See also Figure 3 As shown, the comparison module 30 includes:

[0080] A calculation unit 31, configured to perform time synchronization processing on the plurality of real-time accelerations based on an acquisition timestamp, and calculate statistical characteristic values ​​corresponding to any plurality of the inertial measurement units;

[0081] a range determination unit 32, connected to the calculation unit 31, for performing clustering based on a plurality of the statistical characteristic values ​​to determine a first acceleration range;

[0082] The acceleration comparison unit 33 is connected to the range determination unit 32, and is used to determine the first calibration parameter according to the comparison results between the real-time accelerations and the first acceleration range, or to adjust the preset frequency, or to issue a secondary determination instruction.

[0083] Specifically, the embodiment of the present invention accurately aligns the data collected by different inertial measurement units at the same time by setting the calculation unit, thereby ensuring the comparability between the data, laying a foundation for accurately evaluating the working status of each unit and discovering potential differences, calculating the statistical characteristic value corresponding to any inertial measurement unit, and quantitatively describing the acceleration data from multiple dimensions, so as to more comprehensively determine the working characteristics of the inertial measurement unit, and provide rich data basis for subsequent precise calibration, and accurately reflects the reasonable acceleration value range under the current flight conditions and the performance state of the inertial measurement unit by setting the range determination unit. The accuracy of the subsequent judgment of whether each unit is working normally and the accuracy of the calibration work is improved, and the acceleration comparison unit is set to determine the first calibration parameter, so that the deviation of each inertial measurement unit relative to the normal range can be accurately identified, and the calibration parameter can be calculated and corrected in a targeted manner, thereby improving the measurement accuracy of the entire inertial measurement system, ensuring the accuracy of various control, navigation and other operations performed by the aircraft based on the inertial measurement data, and improving the reliability of the entire inertial measurement unit calibration system.

[0084] Specifically, the computing unit includes:

[0085] A time synchronization subunit, used to determine a time difference based on a preset timestamp and an acquisition timestamp, and to perform time synchronization processing on the plurality of real-time accelerations based on the time difference and a data interpolation algorithm;

[0086] The feature calculation subunit is connected to the time synchronization subunit and is used to calculate the actual mean feature, actual variance feature and actual covariance matrix feature corresponding to a plurality of the real-time acceleration values ​​within a preset time window.

[0087] It can be understood that the preset timestamp described in the embodiment of the present invention is a preset acquisition timestamp determined according to the preset acquisition frequency. If the data acquisition frequency is 100 Hz, that is, data is collected 100 times per second, then the preset timestamp needs to generate a new timestamp at a corresponding interval (every 10 milliseconds) to ensure that the time information of each data point can be accurately recorded.

[0088] It can be understood that the mean calculation in the embodiment of the present invention is: the arithmetic mean method is adopted to add up all the real-time acceleration data collected in the time window and divide it by the number of data points to obtain the mean of the acceleration in each coordinate axis direction (such as X, Y, and Z axes, corresponding to different directions of the aircraft) in the time window, so as to characterize the average acceleration of the inertial measurement unit in this time period.

[0089] Variance calculation: The variance of the acceleration data is obtained by calculating the sum of the squares of the difference between each data point and the mean, and then dividing it by the number of data points minus 1. The variance can reflect the degree of dispersion of the acceleration data in the time window. If the variance is too large, it means that the data fluctuates violently, which may indicate that the inertial measurement unit has unstable measurements.

[0090] Covariance matrix calculation: Considering that the acceleration of the aircraft is a three-dimensional vector (usually corresponding to the three coordinate axes of X, Y, and Z), in order to analyze the correlation between the accelerations in different coordinate axis directions, the covariance matrix is ​​calculated. The elements in the covariance matrix represent the degree of linear correlation between the accelerations in different coordinate axis directions. For example, the element in the i-th row and j-th column of the covariance matrix reflects the covariance between the acceleration in the i-th coordinate axis direction and the acceleration in the j-th coordinate axis direction. Through it, we can gain a deeper understanding of the relationship between the various acceleration components, which helps to more comprehensively judge the working status of the inertial measurement unit.

[0091] It can be understood that the range determination unit in the embodiment of the present invention includes:

[0092] A feature integration subunit is used to normalize and integrate a number of statistical feature values ​​corresponding to any inertial measurement unit to obtain a feature vector;

[0093] The clustering analysis subunit is connected to the feature integration subunit, and is used to perform clustering processing on a plurality of the feature vectors based on a clustering algorithm, and determine the first acceleration range based on the clustering result.

[0094] It can be understood that the clustering algorithm in the embodiment of the present invention may be a K-Means clustering algorithm.

[0095] It can be understood that the cluster analysis subunit described in the embodiment of the present invention is used to select the cluster containing the largest number of data points as a benchmark, determine the reasonable interval of its statistical characteristic values ​​such as mean and variance in each coordinate axis direction, and thus construct the first acceleration range. For example, for the X-axis direction, the average value of the X-axis acceleration mean of each unit in the cluster is taken as the center value, and its mean ±1 is used as the first acceleration range in the X-axis direction; the same method is used to determine the corresponding ranges in the Y-axis and Z-axis directions.

[0096] Specifically, the acceleration comparison unit includes:

[0097] a first calculation subunit, configured to calculate an actual proportion of a plurality of real-time accelerations that are not within a first acceleration range, compare the actual proportion with a first preset proportion, and when the actual proportion is greater than or equal to the first preset proportion, calculate a regression coefficient based on the plurality of abnormal real-time accelerations as the first calibration parameter;

[0098] a frequency adjustment subunit, connected to the first calculation subunit, for adjusting the preset frequency when the actual proportion is less than the first preset proportion and greater than the second preset proportion;

[0099] The instruction generation subunit is connected to the frequency adjustment subunit, and is used to generate a secondary judgment instruction when the actual proportion is less than the second preset proportion.

[0100] It can be understood that the first preset proportion in the embodiment of the present invention is 1 / 3;

[0101] The second preset ratio is 1 / 6.

[0102] It can be understood that the first calculation subunit of the embodiment of the present invention is used to take several abnormal real-time acceleration values ​​as dependent variables and normal real-time acceleration values ​​as independent variables to construct a multivariate linear regression model, and to fit and solve the model through optimization algorithms such as the least squares method to obtain the regression coefficient. This is the prior art and will not be repeated here.

[0103] It can be understood that the frequency adjustment subunit described in the embodiment of the present invention is used to adjust the preset frequency by using the difference between the first preset proportion and the actual proportion as an increase factor when the actual proportion is less than the first preset proportion and greater than the second preset proportion, and the adjusted preset frequency = (1+increase factor)×preset frequency.

[0104] Specifically, the route determination module includes:

[0105] A route drawing unit, used for receiving the secondary judgment instruction and drawing a real-time route map based on the initial position and the real-time accelerations;

[0106] A route comparison unit is connected to the route drawing unit, and is used to calculate the trajectory similarity between the real-time route map and the preset route map, determine the second calibration parameter based on the comparison results of the trajectory similarity with the first preset similarity and the second preset similarity, or adjust the first acceleration range, or issue three judgment instructions.

[0107] It can be understood that the first preset similarity in the embodiment of the present invention is 90%;

[0108] The second preset similarity is 85%.

[0109] Specifically, the route drawing unit includes:

[0110] A trajectory calculation subunit, used to construct a plurality of flight trajectory point sequences based on a plurality of real-time acceleration data and initial position information;

[0111] The graphics drawing subunit is connected to the trajectory calculation subunit and is used to draw a real-time route map based on a plurality of flight trajectory point sequences.

[0112] It can be understood that the initial position information in the embodiment of the present invention is the position of the aircraft corresponding to when the characteristics of the test aircraft are collected.

[0113] Specifically, the route comparison unit includes:

[0114] A similarity calculation subunit, used to calculate the similarity between the real-time route map and the preset route map based on a similarity algorithm;

[0115] The similarity comparison subunit is used to compare the actual similarity with the preset similarity. If the actual similarity is greater than or equal to the first preset similarity, three judgment instructions are generated. If the actual similarity is less than the first preset similarity and greater than or equal to the second preset similarity, the first acceleration range is adjusted. If the actual similarity is less than or equal to the second preset similarity, the second calibration parameter is determined.

[0116] It can be understood that the similarity comparison subunit described in the embodiment of the present invention is used to expand the first acceleration range when the actual similarity is less than the first preset similarity and is greater than or equal to the second preset similarity. When the actual similarity is less than or equal to the second preset similarity, the second calibration parameter is the difference between the second preset similarity and the actual similarity.

[0117] Specifically, the temperature judgment module includes:

[0118] The temperature collection unit is used to receive three judgment instructions and collect several real-time temperature values;

[0119] A curve analysis unit connected to the temperature acquisition unit is used to draw a temperature change curve based on a number of real-time temperature values, analyze the change trend and degree of the temperature change curve, and determine whether there is an abnormality in the temperature change according to the analysis result;

[0120] The calibration parameter determination unit is used to determine a third calibration parameter according to the analysis result of the temperature variation curve.

[0121] It can be understood that, according to the analysis results of the curve analysis subunit, if there is a significant correlation between temperature and acceleration, a multivariate linear regression model is used to establish a mathematical relationship between temperature and acceleration deviation. With the temperature value as the independent variable and the deviation of acceleration in the three coordinate axes of X, Y, and Z as the dependent variable, a regression analysis is performed on a number of temperature data and their corresponding acceleration deviation data to determine the regression coefficient, thereby obtaining the third calibration parameter.

[0122] It can be understood that the calibration module is used to calibrate the corresponding inertial measurement unit according to the first calibration parameter, the second calibration parameter and the third calibration parameter.

[0123] It can be understood that an example of the calibration module described in an embodiment of the present invention is that for the measurement value of the acceleration data in the X-axis direction, the scale is first adjusted according to the X-axis scale correction coefficient in the first calibration parameter, and then the X-axis zero bias correction value in the second calibration parameter is added, and finally temperature compensation is performed according to the current temperature value and the temperature compensation coefficient in the third calibration parameter to obtain the corrected X-axis acceleration data.

[0124] See also Figure 4 As shown, an embodiment of the present invention further provides a calibration method for an inertial measurement unit, the method comprising:

[0125] Step S100, determining a number of key points of the test aircraft, and setting a number of inertial measurement units on the test aircraft based on the key points;

[0126] Step S200, collecting a plurality of real-time accelerations obtained by any of the inertial measurement units based on a preset frequency;

[0127] Step S300, comparing a plurality of real-time accelerations collected by the inertial measurement units, determining a first acceleration range based on the comparison result, determining a first calibration parameter according to the comparison result between the plurality of real-time accelerations and the first acceleration range, or adjusting a preset frequency, or issuing a secondary determination instruction;

[0128] Step S400, receiving a secondary judgment instruction, drawing a real-time route map based on any one of the real-time accelerations, determining a second calibration parameter based on a comparison result between the real-time route map and a preset route map, or adjusting the first acceleration range, or issuing a third judgment instruction;

[0129] Step S500, receiving three judgment instructions, collecting real-time temperature values ​​at the corresponding moments of a plurality of real-time accelerations in real time, drawing a temperature change curve based on the plurality of real-time temperature values, analyzing the temperature change curve, and determining a third calibration parameter according to the analysis result;

[0130] Step S600: calibrate the measurement data of the inertial measurement unit based on the first calibration parameter, the second calibration parameter and / or the third calibration parameter to obtain calibration data.

[0131] Specifically, the calibration method of the inertial measurement unit provided in the embodiment of the present invention can execute the calibration system of the inertial measurement unit mentioned above to achieve the same technical effect, which will not be described in detail here.

[0132] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

[0133] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A calibration system for an inertial measurement unit, characterized in that: include: A setting module is used to determine a number of key points of the test aircraft, and to set a number of inertial measurement units on the test aircraft based on the key points; A data acquisition module, connected to the setting module, for acquiring a number of real-time accelerations obtained by any of the inertial measurement units based on a preset frequency; a comparison module connected to the data acquisition module, for comparing a plurality of real-time accelerations acquired by the inertial measurement units, determining a first acceleration range based on the comparison result, determining a first calibration parameter according to the comparison result between the plurality of real-time accelerations and the first acceleration range, or adjusting a preset frequency, or issuing a secondary judgment instruction; a route determination module, connected to the comparison module, for receiving a secondary determination instruction, drawing a real-time route map based on any one of the real-time accelerations, determining a second calibration parameter based on a comparison result between the real-time route map and a preset route map, or adjusting a first acceleration range, or issuing a tertiary determination instruction; a temperature judgment module, connected to the route judgment module, for receiving three judgment instructions, collecting real-time temperature values ​​at the corresponding moments of a plurality of real-time accelerations in real time, drawing a temperature change curve based on the plurality of real-time temperature values, analyzing the temperature change curve, and determining a third calibration parameter according to the analysis result; a calibration module, configured to calibrate measurement data of the inertial measurement unit based on the first calibration parameter, the second calibration parameter and / or the third calibration parameter to obtain calibration data; The comparison module comprises: A calculation unit, used for performing time synchronization processing on the plurality of real-time accelerations based on the acquisition timestamp, and calculating statistical characteristic values ​​corresponding to any plurality of the inertial measurement units; a range determination unit, connected to the calculation unit, for performing clustering based on a plurality of the statistical characteristic values ​​to determine a first acceleration range; An acceleration comparison unit connected to the range determination unit, for determining a first calibration parameter according to a comparison result between a plurality of real-time accelerations and a first acceleration range, or adjusting a preset frequency, or issuing a secondary determination instruction; The acceleration comparison unit comprises: a first calculation subunit, configured to calculate an actual proportion of a plurality of real-time accelerations that are not within a first acceleration range, compare the actual proportion with a first preset proportion, and when the actual proportion is greater than or equal to the first preset proportion, calculate a regression coefficient based on the plurality of abnormal real-time accelerations as the first calibration parameter; a frequency adjustment subunit, connected to the first calculation subunit, for adjusting the preset frequency when the actual proportion is less than the first preset proportion and greater than the second preset proportion; The instruction generation subunit is connected to the frequency adjustment subunit, and is used to generate a secondary judgment instruction when the actual proportion is less than the second preset proportion.

2. The calibration system of the inertial measurement unit according to claim 1, characterized in that: The setting module includes: A structure determination unit is used to perform flight simulation on the test aircraft, determine stress and strain distribution, and determine several key points based on the stress and strain distribution results; The setting unit is connected to the structure determination unit and is used to set inertial measurement units at several of the key points.

3. The calibration system of an inertial measurement unit according to claim 1, characterized in that: The computing unit comprises: A time synchronization subunit, used to determine a time difference based on a preset timestamp and an acquisition timestamp, and to perform time synchronization processing on the plurality of real-time accelerations based on the time difference and a data interpolation algorithm; The feature calculation subunit is connected to the time synchronization subunit and is used to calculate the actual mean feature, actual variance feature and actual covariance matrix feature corresponding to a plurality of the real-time acceleration values ​​within a preset time window.

4. The calibration system of an inertial measurement unit according to claim 1, characterized in that: The route determination module comprises: A route drawing unit, used for receiving the secondary judgment instruction and drawing a real-time route map based on the initial position and the real-time accelerations; A route comparison unit is connected to the route drawing unit, and is used to calculate the trajectory similarity between the real-time route map and the preset route map, determine the second calibration parameter based on the comparison results of the trajectory similarity with the first preset similarity and the second preset similarity, or adjust the first acceleration range, or issue three judgment instructions.

5. The calibration system of the inertial measurement unit according to claim 4, characterized in that: The route drawing unit comprises: A trajectory calculation subunit, used to construct a plurality of flight trajectory point sequences based on a plurality of real-time acceleration data and initial position information; The graphics drawing subunit is connected to the trajectory calculation subunit and is used to draw a real-time route map based on a plurality of flight trajectory point sequences.

6. The calibration system of the inertial measurement unit according to claim 5, characterized in that: The route comparison unit comprises: A similarity calculation subunit, used to calculate the similarity between the real-time route map and the preset route map based on a similarity algorithm; The similarity comparison subunit is used to compare the actual similarity with the preset similarity. If the actual similarity is greater than or equal to the first preset similarity, three judgment instructions are generated. If the actual similarity is less than the first preset similarity and greater than or equal to the second preset similarity, the first acceleration range is adjusted. If the actual similarity is less than or equal to the second preset similarity, the second calibration parameter is determined.

7. The calibration system of the inertial measurement unit according to claim 6, characterized in that: The temperature judgment module comprises: The temperature collection unit is used to receive three judgment instructions and collect several real-time temperature values; A curve analysis unit connected to the temperature acquisition unit is used to draw a temperature change curve based on a number of real-time temperature values, analyze the change trend and degree of the temperature change curve, and determine whether there is an abnormality in the temperature change according to the analysis result; The calibration parameter determination unit is used to determine a third calibration parameter according to the analysis result of the temperature variation curve.

8. A calibration method for a calibration system of an inertial measurement unit according to any one of claims 1 to 7, characterized in that: include: Determine a number of key points of the test aircraft, and set a number of inertial measurement units on the test aircraft based on the number of key points; Collecting a plurality of real-time accelerations obtained by any of the inertial measurement units based on a preset frequency; Comparing a plurality of real-time accelerations collected by the inertial measurement units, determining a first acceleration range based on the comparison result, determining a first calibration parameter according to the comparison result between the plurality of real-time accelerations and the first acceleration range, or adjusting a preset frequency, or issuing a secondary determination instruction; Receiving a secondary judgment instruction, drawing a real-time route map based on any one of the real-time accelerations, determining a second calibration parameter based on a comparison result between the real-time route map and a preset route map, or adjusting the first acceleration range, or issuing a third judgment instruction; receiving three judgment instructions, collecting real-time temperature values ​​at the moments corresponding to the real-time accelerations, drawing a temperature change curve based on the real-time temperature values, analyzing the temperature change curve, and determining a third calibration parameter according to the analysis result; The measurement data of the inertial measurement unit is calibrated based on the first calibration parameter, the second calibration parameter and / or the third calibration parameter to obtain calibration data.

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