Calibration method, device, equipment and readable storage medium of inertial measurement unit

Abstract

The present application provides a calibration method for an inertial measurement unit, which can use a target turntable to perform a transposition operation, and realize the calibration of the gyro scale coefficient and the table scale coefficient through data comparison; implement the transposition excitation through the target turntable, set the state variables to be estimated and the observed quantities, and realize the calibration of the IMU error parameters and the IMU zero bias parameters. The present application can be applied to both strapdown inertial navigation with a built-in dual-axis transposition device and a pure strapdown IMU that uses an external turntable for transposition, and is compatible with both the presence and absence of an external arm. Therefore, the calibration process will not affect the IMU calibration accuracy, thereby improving the accuracy of the calibration results. The present application also provides a calibration device, equipment and computer-readable storage medium for an inertial measurement unit.

Description

Technical Field

[0001] The present application relates to the field of computer technology, and in particular to a calibration method, device, equipment and readable storage medium of an inertial measurement unit. Background Art

[0002] The inertial navigation system is an autonomous navigation system with good concealment and the ability to work in various complex environments. The strapdown inertial navigation system is developed based on the platform inertial navigation system.

[0003] In the strapdown inertial navigation system, the inertial measurement unit (IMU) is its most important component. Accurate calibration of the IMU is an important way to improve the accuracy of strapdown inertial navigation orientation and attitude measurement. Among them, the discrete calibration method has been widely studied and applied, and the technology is relatively mature, but it requires the use of a laboratory turntable for rotation and hovering. The calibration accuracy depends on the accuracy of the turntable, and there are limitations on the calibration occasion and calibration accuracy.

[0004] With the continuous development of inertial navigation system application platforms, higher requirements are put forward for the high dynamic orientation and attitude measurement accuracy of inertial navigation systems. Therefore, it is necessary to further improve the calibration accuracy of IMU. However, although the discrete calibration method has the advantages of short time, mature technology, and engineering application automation, the orthogonality and angular position errors of the turntable axis of the discrete calibration method lead to the same magnitude of calibration errors in the IMU installation error angle, which has a great impact on the high dynamic orientation and attitude measurement accuracy. Summary of the invention

[0005] The present application provides a calibration method, apparatus, device and computer-readable storage medium for an inertial measurement unit, which can improve the calibration accuracy of the inertial measurement unit.

[0006] In a first aspect, the present application provides a calibration method for an inertial measurement unit, wherein the inertial measurement unit IMU includes a three-axis target gyroscope and a target addition table, wherein the target addition table is an accelerometer, and the method includes all or part of the following calibration steps:

[0007] Controlling the target turntable to rotate in different ways, using the target gyro to detect the rotation angular velocity, and calibrating the scale coefficient of the target gyro based on the comparison result between the gyro detection velocity and the actual velocity of the turntable;

[0008] Control the target turntable to rotate according to different static modes, use the target adding table to detect the gravity acceleration in each static state, and calibrate the scale coefficient of the target adding table based on the comparison result between the detection speed of the adding table and the actual speed of the turntable;

[0009] Implementing a three-axis rotation excitation on the target turntable, taking an IMU error parameter as a state variable to be estimated and a velocity error as an observation, estimating and calibrating the IMU error parameter, wherein the IMU error parameter includes relevant parameters that cause an IMU detection error;

[0010] The target turntable is subjected to rotation excitation based on the azimuth axis among the three axes, and the IMU zero bias parameters are used as the state variables to be estimated and the velocity error is used as the observed quantity, so as to estimate and calibrate the IMU zero bias parameters.

[0011] Optionally, the control target turntable is indexed in different rotation modes, including:

[0012] The target turntable is controlled to rotate in the forward and reverse directions based on the three axes of the target gyroscope.

[0013] Optionally, controlling the target turntable to perform rotation according to different static modes includes:

[0014] The target turntable is controlled to be stationary in the forward and reverse directions based on the three axes of the target plus table.

[0015] Optionally, the target turntable is subjected to a three-axis-based indexing excitation, including:

[0016] According to the preset rotation sequence of the three axes, the three axes are used as references and rotated in sequence according to the preset directions; according to the reverse order of the preset rotation sequence, the three axes are used as references and rotated in sequence according to the preset directions; the rotation operations of the preset rotation sequence and the reverse order are repeated until a stop rotation instruction is received.

[0017] Optionally, implementing a rotation excitation based on an azimuth axis among three axes on the target turntable comprises:

[0018] The target turntable is controlled to rotate forwardly based on the azimuth axis among the three axes; the target turntable is controlled to rotate reversely based on the azimuth axis; and the forward and reverse rotation operations are repeated until a stop rotation instruction is received.

[0019] Optionally, the method further includes:

[0020] The IMU calibration results are solved offline using the data saved during the IMU calibration process, and the results of the offline solution are used to verify the correctness of the calibration results.

[0021] Optionally, the target turntable is a turntable in a dual-axis indexing device of a strapdown inertial navigation system, or is an external turntable of the strapdown inertial navigation system.

[0022] In a second aspect, the present application provides a calibration device for an inertial measurement unit, wherein the inertial measurement unit IMU includes a three-axis target gyroscope and a target addition table, wherein the target addition table is an accelerometer, and the device includes all or part of the following calibration units:

[0023] A gyro coefficient calibration unit, used to control the target turntable to rotate in different ways, detect the rotation angular velocity using the target gyro, and calibrate the scale coefficient of the target gyro based on the comparison result between the gyro detection speed and the actual speed of the turntable;

[0024] The addition table coefficient calibration unit is used to control the target turntable to be indexed according to different static modes, use the target addition table to detect the gravity acceleration in each static state, and calibrate the scale coefficient of the target addition table based on the comparison result between the addition table detection speed and the actual speed of the turntable;

[0025] An error parameter calibration unit is used to implement a three-axis rotation excitation on the target turntable, take an IMU error parameter as a state variable to be estimated, take a velocity error as an observation, and estimate and calibrate the IMU error parameter, wherein the IMU error parameter includes relevant parameters that cause IMU detection errors;

[0026] The zero bias parameter calibration unit is used to implement a rotation excitation based on the azimuth axis among the three axes on the target turntable, and estimate and calibrate the IMU zero bias parameters using the IMU zero bias parameters as the state variables to be estimated and the velocity error as the observed quantity.

[0027] Optionally, when controlling the target turntable to rotate in different rotation modes, the gyro coefficient calibration unit is specifically used to:

[0028] The target turntable is controlled to rotate in the forward and reverse directions based on the three axes of the target gyroscope.

[0029] Optionally, when controlling the target turntable to perform indexing in different stationary modes, the table addition coefficient calibration unit is specifically used to:

[0030] The target turntable is controlled to be stationary in the forward and reverse directions based on the three axes of the target plus table.

[0031] Optionally, when the error parameter calibration unit implements the three-axis-based indexing excitation on the target turntable, it is used to:

[0032] According to the preset rotation sequence of the three axes, the three axes are used as references and rotated in sequence according to the preset directions; according to the reverse order of the preset rotation sequence, the three axes are used as references and rotated in sequence according to the preset directions; the rotation operations of the preset rotation sequence and the reverse order are repeated until a stop rotation instruction is received.

[0033] Optionally, when the zero bias parameter calibration unit implements the rotation excitation based on the azimuth axis among the three axes on the target turntable, it is used to:

[0034] The target turntable is controlled to rotate forwardly based on the azimuth axis among the three axes; the target turntable is controlled to rotate reversely based on the azimuth axis; and the forward and reverse rotation operations are repeated until a stop rotation instruction is received.

[0035] Optionally, the device further comprises:

[0036] The offline solution unit is used to use the data saved during the IMU calibration process to perform offline solution on the IMU calibration result, and the result of the offline solution is used to verify the correctness of the calibration result.

[0037] Optionally, the target turntable is a turntable in a dual-axis indexing device of a strapdown inertial navigation system, or is an external turntable of the strapdown inertial navigation system.

[0038] In a third aspect, the present application provides an electronic device, including: a processor and a memory;

[0039] The memory is used to store computer programs;

[0040] The processor is used to execute the calibration method of the inertial measurement unit by calling the computer program.

[0041] In a fourth aspect, the present application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the calibration method of the above-mentioned inertial measurement unit.

[0042] In the technical solution provided by the present application, the target turntable can be used for the indexing operation, and the calibration of the gyro scale coefficient and the table scale coefficient can be realized through data comparison; the indexing excitation is implemented through the target turntable, and the state variables and observations to be estimated are set to realize the calibration of the IMU error parameters and the IMU zero bias parameters. The present application can be applied to both the strapdown inertial navigation with its own dual-axis indexing device and the pure strapdown IMU that uses an external turntable for indexing, and is compatible with both the presence and absence of an external arm. Therefore, the calibration process will not affect the IMU calibration accuracy, thereby improving the accuracy of the calibration results. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is an example diagram of a strapdown inertial navigation system-level calibration device shown in this application;

[0044] Figure 2 A schematic diagram of a flow chart of a calibration method of an inertial measurement unit shown in the present application;

[0045] Figure 3 This is one of the schematic diagrams of the transposition shown in this application;

[0046] Figure 4 This is the second schematic diagram of the transposition shown in this application;

[0047] Figure 5 This is the third schematic diagram of the transposition shown in this application;

[0048] Figure 6 This is the fourth schematic diagram of the transposition shown in this application;

[0049] Figure 7 A schematic diagram of the composition of a calibration device for an inertial measurement unit shown in the present application;

[0050] Figure 8 This is a schematic diagram of the structure of an electronic device shown in this application. DETAILED DESCRIPTION

[0051] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0052] The terms used in this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The singular forms of "a", "said" and "the" used in this application and the appended claims are also intended to include plural forms unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0053] It should be understood that although the terms first, second, third, etc. may be used in the present application to describe various information, these information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining".

[0054] Before introducing the embodiments of the present application, the inertial measurement unit IMU in the strapdown inertial navigation system is first introduced:

[0055] The inertial measurement unit (IMU) contains three single-axis accelerometers and three single-axis gyroscopes. The accelerometers detect the acceleration signals of the object in the three independent axes of the carrier coordinate system, while the gyroscopes detect the angular velocity signals of the carrier relative to the navigation coordinate system, measuring the angular velocity and acceleration of the object in three-dimensional space, and using this to calculate the object's posture.

[0056] The embodiment of the present application provides a calibration method for an inertial measurement unit (IMU), specifically an IMU system-level calibration method that is convenient for engineering applications, that is, a strapdown inertial navigation system-level calibration engineering automation implementation method, which is applicable to a strapdown inertial navigation system with a dual-axis indexing mechanism and a pure strapdown IMU. Among them, the dual-axis strapdown inertial navigation system uses its own indexing mechanism for indexing, and the pure strapdown IMU needs to be indexed with the help of an external turntable. The calibration processes of the two are similar, but the latter needs to consider the fact that the turntable rotation center does not coincide with the IMU sensitive center, that is, the influence of the external rod arm. The embodiment of the present application is an IMU calibration method that can be compatible with these two types of inertial navigation systems, and realizes the function of "one-click" calibration of all parameters or specified parameters of IMU, that is, it can "one-click" realize the strapdown inertial navigation system-level calibration function, and at the same time, the original data of the stored gyroscope and the addition table (i.e., accelerometer) can be used for offline solution and re-inspection, thereby improving the production efficiency of the strapdown inertial navigation and enhancing the batch production capacity of the strapdown inertial navigation.

[0057] That is to say, the IMU calibration method provided in the embodiment of the present application aims to realize the high-precision system-level calibration function of the strapdown inertial navigation in a "one-click" manner. It is a "one-click" system-level calibration method suitable for wide engineering applications. The method is compatible with both the presence and absence of an external arm. With the help of a dual-axis rotation device, it realizes the function of calibrating all parameters or specified parameters of the IMU. At the same time, the saved gyroscope and table original data can be used for offline solution and verification.

[0058] The following is a detailed introduction to the “calibration method of an inertial measurement unit” provided in an embodiment of the present application.

[0059] It should be noted that, for the inertial measurement unit IMU included in the strapdown inertial navigation system, the embodiment of the present application defines the gyroscope and accelerometer included in the IMU as a target gyroscope and a target accelerometer, respectively, that is, the IMU includes a three-axis target gyroscope and a target accelerometer.

[0060] See also Figure 1 , is an example diagram of a strapdown inertial navigation system-level calibration device provided in an embodiment of the present application, the device includes an IMU, a set of indexing mechanisms and a system-level calibration software. The calibration software will implement the calibration method of the inertial measurement unit IMU in an embodiment of the present application.

[0061] See also Figure 2 , is a flow chart of a calibration method of an inertial measurement unit provided in an embodiment of the present application, the method comprising all or part of the calibration steps in the following steps S201-S204:

[0062] S201: Control the target turntable to rotate in different ways, use the target gyroscope to detect the rotation angular velocity, and calibrate the scale coefficient of the target gyroscope based on the comparison result between the gyroscope detection speed and the actual speed of the turntable.

[0063] In an embodiment of the present application, the target turntable can be a turntable in a dual-axis indexing device of a strapdown inertial navigation system, or an external turntable of a strapdown inertial navigation system. Specifically, the embodiment of the present application is applicable to the system-level calibration of a strapdown inertial navigation system with a dual-axis indexing device and a pure strapdown IMU. The difference between the two is that the former ensures that the rotation center of the turntable is approximately coincident with the sensitive center of the IMU during structural design, and the influence of the external lever arm can be ignored in principle for the system-level calibration; while the latter needs to be installed on an external turntable, and the sensitive center of the IMU often does not coincide with the rotation center of the turntable. If the external lever arm is not considered during calibration, when the angular velocity excitation is large, it will have a greater impact on the calibration accuracy of the IMU. The embodiment of the present application takes into account both working conditions at the same time. Except that the hardware electrical connection needs to be adaptively changed, the calibration process remains consistent, which broadens the scope of application of the system-level calibration method.

[0064] In this step S201, the scale coefficient of the target gyroscope is roughly calibrated by using the angular velocity of the target turntable as input and the detection data of the angular velocity of the target gyroscope in the IMU as output, and using the two to preliminarily calibrate the scale coefficient of the target gyroscope.

[0065] In one implementation of the embodiment of the present application, "controlling the target turntable to rotate in different rotation modes" in S201 may include: controlling the target turntable to rotate in the forward and reverse directions respectively with the three axes of the target gyroscope as references. In this implementation, the target turntable is set to rotate continuously in the forward and reverse directions along the three sensitive axes of the target gyroscope. During this process, the detection data of the target gyroscope is collected so as to compare the angular velocity detected by the target gyroscope with the actual angular velocity of the target turntable. Based on the comparison result, a preliminary result of the gyroscope scale factor is obtained, that is, the scale coefficient of the target gyroscope is obtained.

[0066] like Figure 3 One of the transposition diagrams shown. Figure 3 In the example, the three sensitive axes of the target gyroscope are divided into the x-axis, y-axis and z-axis. The target turntable is set to perform the indexing operation based on the y-axis, z-axis and x-axis. The indexing operation sequence is as follows:

[0067] Taking the y-axis as the reference (i.e. the y-axis remains unchanged), rotate the xz plane in the positive direction ( Figure 3 The viewing angle is rotated outward), and then the xz face is rotated in the opposite direction ( Figure 3 The viewing angle is rotated inward); taking the z-axis as the reference (i.e. the z-axis remains unchanged), the xy plane is rotated in the positive direction ( Figure 3 The viewing angle is rotated to the left), and then the xy plane is rotated in the opposite direction ( Figure 3 The viewing angle is rotated to the right); taking the x-axis as the reference (i.e. the x-axis remains unchanged), the yz plane is rotated in the positive direction ( Figure 3 The viewing angle is rotated outward), and then the yz plane is rotated in the opposite direction ( Figure 3 The perspective is rotated inwards).

[0068] It should be noted that the present embodiment does not limit the indexing method of step S201, which can adopt the above Figure 3 The illustrated indexing method may also be used in other indexing methods (such as changing the order of sensitive axes and / or changing the order of indexing directions).

[0069] S202: Control the target turntable to rotate according to different static modes, use the target meter to detect the gravity acceleration in each static state, and calibrate the scale coefficient of the target meter based on the comparison result of the meter detection speed and the actual speed of the turntable.

[0070] In this step S202, the scale coefficient of the target meter is roughly calibrated. The calibration method uses the gravitational acceleration of the target turntable in a static horizontal state as input, and the detection data of the acceleration of the target meter in the IMU as output, and uses the two to preliminarily calibrate the scale coefficient of the target meter.

[0071] In one implementation of the embodiment of the present application, "controlling the target turntable to rotate according to different static modes" in S202 may include: controlling the target turntable to be static in the forward and reverse directions respectively based on the three axes of the target plus table. In this implementation, the target turntable is set to be static in the forward and reverse directions along the three sensitive axes of the target plus table, and the target plus table detects the gravitational acceleration in each static state, so as to compare the acceleration detected by the target plus table with the actual acceleration of the target turntable, and based on the comparison result, a preliminary result of the scale factor of the plus table is obtained, that is, the scale coefficient of the target plus table is obtained.

[0072] like Figure 4 The second schematic diagram of the translocation is shown in FIG. Figure 4 In the target table, the three sensitive axes are divided into x-axis, y-axis and z-axis. The target turntable is set to perform indexing operation based on y-axis, z-axis and x-axis. The indexing operation sequence is as follows:

[0073] Take the z-axis as the reference for static placement, and first place it in the positive direction of the z-axis ( Figure 4 The viewing angle is z-axis upward), and then stand still in the opposite direction of z-axis ( Figure 4 The viewing angle is the z-axis downward); take the x-axis as the reference for static placement, and first place it in the positive direction of the x-axis ( Figure 4 The viewing angle is x-axis upward), and then stand still in the opposite direction of the x-axis ( Figure 4 The viewing angle is from the x-axis downward); take the y-axis as the reference for static placement, and first place it in the positive direction of the y-axis ( Figure 4 The viewing angle is y-axis upward), and then stand still in the opposite direction of the y-axis ( Figure 4 The viewing angle is downward on the y-axis).

[0074] It should be noted that the present embodiment does not limit the indexing method of step S202, which can adopt the above Figure 4 The illustrated indexing method may also be used in other indexing methods (such as changing the order of sensitive axes and / or changing the order of indexing directions).

[0075] S203: Implement three-axis rotation excitation on the target turntable, use IMU error parameters as state variables to be estimated and velocity errors as observation quantities, and estimate and calibrate IMU error parameters, wherein the IMU error parameters include relevant parameters that cause IMU detection errors.

[0076] In this step S203, the IMU installation error matrix, lever arm parameters, etc. are calibrated. Specifically, a series of transposition excitations can be implemented, that is, based on the angular velocity excitation of the three axes, so that the IMU error parameters such as the gyro installation error, lever arm error, and quadratic error of the gyro in the IMU are transferred to the navigation results (such as position, velocity, attitude, etc.). Therefore, a 39-dimensional Kalman filter can be designed, with the IMU error parameters as the state variables to be estimated and the velocity error as the observed quantity, and the piecewise linear constant system (PWCS) theory and the singular value decomposition method are used to estimate the IMU error parameters.

[0077] In one implementation of the embodiment of the present application, "implementing three-axis rotation excitation on the target turntable" in S203 may include: according to the preset rotation axis order of the three axes, taking the three axes as the reference, and rotating in the preset direction in sequence; according to the reverse order of the preset rotation axis order, taking the three axes as the reference, and rotating in the preset direction in sequence; repeating the rotation operation of the preset rotation axis order and the reverse order until a stop rotation instruction is received.

[0078] In this implementation, the x-axis, y-axis and z-axis can be sorted, and based on the sorting results, the rotation operation in the same direction can be performed with each axis as the reference in turn; after completion, the rotation operation in the same direction can be performed with each axis as the reference in turn based on the reverse order of the above three-axis sorting results, and one round of rotation operation is completed; then, the above rotation operation can be continuously repeated until a stop rotation instruction is received, wherein the stop rotation instruction can be triggered manually or preset manually (for example, setting the rotation operation duration, or completing the above N rounds of operations).

[0079] like Figure 5 The third schematic diagram of the translocation is shown in FIG. Figure 5 In the process, the Y-axis, X-axis and Z-axis are used as references in sequence, and then the Z-axis, X-axis and Y-axis are used as references in sequence, and the direction of each translation is the same.

[0080] It should be noted that the present embodiment does not limit the indexing method of step S203, which can adopt the above Figure 5 The illustrated indexing method may also be used in other indexing methods (such as changing the order of sensitive axes and / or changing the order of indexing directions).

[0081] S204: Implementing a rotation excitation based on the azimuth axis among the three axes on the target turntable, taking the IMU zero bias parameter as the state variable to be estimated and the velocity error as the observed quantity, and estimating and calibrating the IMU zero bias parameter.

[0082] In this step S204, the IMU zero bias (zero point bias) parameters are calibrated. Specifically, the IMU zero bias parameters can be estimated by implementing the displacement excitation of the orientation axis in the three axes, designing a 12-dimensional Kalman filter, using the IMU zero bias parameters as the state variables to be estimated, using the velocity error as the observed quantity, and using the PWCS theory and singular value decomposition method.

[0083] In one implementation of the embodiment of the present application, "implementing rotation excitation on the target turntable based on the azimuth axis among the three axes" in S204 may include: controlling the target turntable to rotate forward based on the azimuth axis among the three axes; controlling the target turntable to rotate reversely based on the azimuth axis; repeating the above-mentioned forward rotation and reverse rotation operations until a stop rotation instruction is received.

[0084] like Figure 6 The fourth transposition diagram shown in FIG. Figure 6 In the example, the z-axis is the azimuth axis. Taking the z-axis as the reference (i.e. the z-axis remains unchanged), first rotate the xy plane in the positive direction ( Figure 6 The viewing angle is rotated to the left), and then the xy plane is rotated in the opposite direction ( Figure 6 The viewing angle is rotated to the right); then, rotate the xy face in the opposite direction ( Figure 6 The viewing angle is rotated to the right), and then the xy plane is rotated in the positive direction ( Figure 6 The viewing angle is rotated to the left), and one round of operation is completed at this time; then, the above-mentioned rotation operation can be continuously repeated until a stop rotation instruction is received, wherein the stop rotation instruction can be triggered manually or preset manually (for example, setting the rotation operation duration, or completing the above-mentioned N rounds of operation).

[0085] It should be noted that the present embodiment does not limit the indexing method of step S204, which can adopt the above Figure 6 The illustrated indexing method may also be used in other indexing methods (such as changing the order of sensitive axes and / or changing the order of indexing directions).

[0086] It should also be noted that the embodiment of the present application does not limit the execution order of the above-mentioned calibration steps, and the order can be based on the system default order or manually set order.

[0087] Furthermore, the embodiment of the present application may also include: using the data saved during the IMU calibration process to perform offline solution on the IMU calibration result, wherein the result of the offline solution is used to verify the correctness of the calibration result. Specifically, the automated system-level calibration method provided in the embodiment of the present application can be directly applied to engineering, and the IMU error parameters and other data are automatically written into the DSP after the calibration is completed; in order to ensure that the calibration results are accurate and reliable, the functions of data storage and offline solution verification are added, and the gyro and table raw data saved during online calibration can be used for offline solution, and the results are consistent with the online calibration results.

[0088] Furthermore, based on Figure 1 The hardware electrical connection relationship of each part in the device shown is used to further illustrate the implementation steps of the embodiment of the present application.

[0089] 1. Full parameter calibration

[0090] (1) IMU is powered on and the system enters the ready state after initialization is completed;

[0091] (2) Set the serial port characteristics for turntable and IMU data acquisition;

[0092] (3) When "Start full parameter calibration" is selected, the system-level calibration software will run in sequence according to the calibration order of all parameters, and the process data will be displayed on the software interface. After the calibration is completed, the software will automatically write the calibration parameter results into the register of the DSP specified address of the IMU.

[0093] 2. Calibration of some parameters

[0094] (1) IMU is powered on and the system enters the ready state after initialization is completed;

[0095] (2) Set the serial port characteristics for turntable and IMU data acquisition;

[0096] (3) When some parameters that need to be calibrated are selected (the above-mentioned scale factor / installation error matrix, lever arm / zero bias), the system-level calibration software will run in sequence according to the calibration order of some parameters, and the process data will be displayed on the interface. After the calibration is completed, the software will automatically write the calibration parameter results into the register of the DSP specified address of the IMU.

[0097] 3. Offline solution

[0098] (1) Select the IMU raw data file and enter the start data number and end data number to be solved;

[0099] (2) Click "Start Offline Solution". The offline solution result data will be displayed on the interface. The offline solution result should be consistent with the online calibration result.

[0100] From the above content introduced in the embodiments of the present application, it can be seen that the embodiments of the present application can be applied to both the strapdown inertial navigation with its own dual-axis indexing device and the pure strapdown IMU system-level calibration using an external turntable for indexing; the "one-click" calibration function of all parameters or partially specified parameters is realized, which improves the production efficiency of the strapdown inertial navigation and enhances the batch production capacity of the strapdown inertial navigation; it has the functions of data storage and re-verification, and can review and recalculate the results of online calibration; the calibration results are more accurate, which is suitable for directional attitude measurement of high-dynamic carriers, and improves the maneuverability of the inertial navigation platform.

[0101] It can be seen that in the calibration method of the inertial measurement unit provided in the above embodiment of the present application, the target turntable can be used for the indexing operation, and the calibration of the gyro scale coefficient and the addition table scale coefficient can be realized through data comparison; the indexing excitation is implemented through the target turntable, and the state variables and observations to be estimated are set to realize the calibration of the IMU error parameters and the IMU zero bias parameters. The embodiment of the present application can be applied to both the strapdown inertial navigation with its own dual-axis indexing device and the pure strapdown IMU that uses an external turntable for indexing, and is compatible with both the presence and absence of an external arm. Therefore, the calibration process will not affect the IMU calibration accuracy, thereby improving the accuracy of the calibration result.

[0102] See also Figure 7 , is a schematic diagram of the composition of a calibration device of an inertial measurement unit provided in an embodiment of the present application. The inertial measurement unit IMU includes a three-axis target gyroscope and a target addition table, the target addition table is an accelerometer, and the device includes all or part of the following calibration units:

[0103] A gyro coefficient calibration unit 710 is used to control the target turntable to rotate in different ways, detect the rotation angular velocity using the target gyro, and calibrate the scale coefficient of the target gyro based on the comparison result between the gyro detection velocity and the actual velocity of the turntable;

[0104] The addition table coefficient calibration unit 720 is used to control the target turntable to be indexed according to different static modes, use the target addition table to detect the gravity acceleration in each static state, and calibrate the scale coefficient of the target addition table based on the comparison result between the addition table detection speed and the actual speed of the turntable;

[0105] The error parameter calibration unit 730 is used to implement a three-axis rotation excitation on the target turntable, use the IMU error parameter as the state variable to be estimated and the velocity error as the observation quantity, and estimate and calibrate the IMU error parameter, wherein the IMU error parameter includes relevant parameters that cause IMU detection errors;

[0106] The zero bias parameter calibration unit 740 is used to implement a rotation excitation based on the azimuth axis among the three axes on the target turntable, and estimate and calibrate the IMU zero bias parameters using the IMU zero bias parameters as the state variables to be estimated and the velocity error as the observed quantity.

[0107] In one implementation of the embodiment of the present application, the gyro coefficient calibration unit 710 is specifically used to:

[0108] The target turntable is controlled to rotate in the forward and reverse directions based on the three axes of the target gyroscope.

[0109] In an implementation of the embodiment of the present application, the table addition coefficient calibration unit 720 is specifically used to control the target turntable to perform indexing according to different stationary modes:

[0110] The target turntable is controlled to be stationary in the forward and reverse directions based on the three axes of the target plus table.

[0111] In one implementation of the embodiment of the present application, when the error parameter calibration unit 730 implements the three-axis-based indexing excitation on the target turntable, it is used to:

[0112] According to the preset rotation sequence of the three axes, the three axes are used as references and rotated in sequence according to the preset directions; according to the reverse order of the preset rotation sequence, the three axes are used as references and rotated in sequence according to the preset directions; the rotation operations of the preset rotation sequence and the reverse order are repeated until a stop rotation instruction is received.

[0113] In an implementation of the embodiment of the present application, when the zero bias parameter calibration unit 740 implements the rotation excitation based on the azimuth axis among the three axes on the target turntable, it is used to:

[0114] The target turntable is controlled to rotate forwardly based on the azimuth axis among the three axes; the target turntable is controlled to rotate reversely based on the azimuth axis; and the forward and reverse rotation operations are repeated until a stop rotation instruction is received.

[0115] In one implementation of the embodiment of the present application, the device further includes:

[0116] The offline solution unit is used to use the data saved during the IMU calibration process to perform offline solution on the IMU calibration result, and the result of the offline solution is used to verify the correctness of the calibration result.

[0117] In an implementation manner of the embodiment of the present application, the target turntable is a turntable in a dual-axis indexing device of a strapdown inertial navigation system, or is an external turntable of the strapdown inertial navigation system.

[0118] The implementation process of the functions and effects of each unit in the above-mentioned device is specifically described in the implementation process of the corresponding steps in the above-mentioned method, and will not be repeated here.

[0119] For the device embodiment, since it basically corresponds to the method embodiment, the relevant parts can refer to the partial description of the method embodiment. The device embodiment described above is only schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the present application scheme. A person of ordinary skill in the art can understand and implement it without paying any creative work.

[0120] The present application also provides an electronic device. The structural diagram of the electronic device is as follows: Figure 8 As shown, the electronic device 8000 includes at least one processor 8001, a memory 8002 and a bus 8003, and the at least one processor 8001 is electrically connected to the memory 8002; the memory 8002 is configured to store at least one computer-executable instruction, and the processor 8001 is configured to execute the at least one computer-executable instruction, thereby executing the steps of any inertial measurement unit calibration method provided in any embodiment or any optional implementation manner in the present application.

[0121] Furthermore, the processor 8001 may be a Field-Programmable Gate Array (FPGA) or other devices with logic processing capabilities, such as a Microcontroller Unit (MCU) or a Central Process Unit (CPU).

[0122] The application of the embodiments of the present application can be applicable to both strapdown inertial navigation systems with built-in dual-axis rotation devices and pure strapdown IMUs that use external turntables for rotation, and is compatible with both situations with and without external arm rods. Therefore, the calibration process will not affect the IMU calibration accuracy, thereby improving the accuracy of the calibration results.

[0123] An embodiment of the present application also provides another computer-readable storage medium storing a computer program, which is used to implement the steps of any inertial measurement unit calibration method provided in any embodiment or any optional implementation manner in the present application when executed by a processor.

[0124] The computer-readable storage medium provided in the embodiments of the present application includes, but is not limited to, any type of disk (including floppy disk, hard disk, optical disk, CD-ROM, and magneto-optical disk), ROM (Read-Only Memory), RAM (Random Access Memory), EPROM (Erasable Programmable Read-Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory), flash memory, magnetic card or optical card. That is, the readable storage medium includes any medium that can store or transmit information in a readable form by a device (e.g., a computer).

[0125] The application of the embodiments of the present application can be applicable to both strapdown inertial navigation systems with built-in dual-axis rotation devices and pure strapdown IMUs that use external turntables for rotation, and is compatible with both situations with and without external arm rods. Therefore, the calibration process will not affect the IMU calibration accuracy, thereby improving the accuracy of the calibration results.

[0126] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A calibration method for an inertial measurement unit, characterized in that: The inertial measurement unit IMU includes a three-axis target gyroscope and a target accelerometer, and the target accelerometer is an accelerometer. The method includes all or part of the following calibration steps: Controlling the target turntable to rotate in different ways, using the target gyro to detect the rotation angular velocity, and calibrating the scale coefficient of the target gyro based on the comparison result between the gyro detection velocity and the actual velocity of the turntable; Control the target turntable to rotate according to different static modes, use the target adding table to detect the gravity acceleration in each static state, and calibrate the scale coefficient of the target adding table based on the comparison result between the detection speed of the adding table and the actual speed of the turntable; Implementing a three-axis rotation excitation on the target turntable, taking an IMU error parameter as a state variable to be estimated and a velocity error as an observation, estimating and calibrating the IMU error parameter, wherein the IMU error parameter includes relevant parameters that cause an IMU detection error; The target turntable is subjected to rotation excitation based on the azimuth axis among the three axes, and the IMU zero bias parameters are used as the state variables to be estimated and the velocity error is used as the observed quantity, so as to estimate and calibrate the IMU zero bias parameters.

2. The method according to claim 1, characterized in that The control target turntable is indexed according to different rotation modes, including: The target turntable is controlled to rotate in the forward and reverse directions based on the three axes of the target gyroscope.

3. The method according to claim 1, characterized in that The controlling the target turntable to perform rotation according to different static modes includes: The target turntable is controlled to be stationary in the forward and reverse directions based on the three axes of the target plus table.

4. The method according to claim 1, characterized in that: Implementing three-axis indexing excitation on the target turntable, including: According to the preset rotation order of the three axes, the three axes are used as references and the rotation is performed in sequence according to the preset directions; According to the reverse order of the preset rotation axis sequence, the three axes are used as references respectively, and the rotation is performed in sequence according to the preset directions; The indexing operation of the preset rotation axis sequence and the reverse sequence is repeated until a stop indexing instruction is received.

5. The method according to claim 1, characterized in that Implementing a rotation excitation based on the azimuth axis among the three axes on the target turntable, comprising: Taking the azimuth axis among the three axes as a reference, controlling the target turntable to rotate in a forward direction; Taking the azimuth axis as a reference, controlling the target turntable to rotate in the opposite direction; The indexing operation of forward rotation and reverse rotation is repeated until a stop indexing instruction is received.

6. The method according to any one of claims 1 to 5, characterized in that: The method further comprises: The IMU calibration results are solved offline using the data saved during the IMU calibration process, and the results of the offline solution are used to verify the correctness of the calibration results.

7. The method according to any one of claims 1 to 5, characterized in that: The target turntable is a turntable in a dual-axis indexing device of a strapdown inertial navigation system, or is an external turntable of the strapdown inertial navigation system.

8. A calibration device for an inertial measurement unit, characterized in that: The inertial measurement unit IMU includes a three-axis target gyroscope and a target addition table, the target addition table is an accelerometer, and the device includes all or part of the following calibration units: A gyro coefficient calibration unit, used to control the target turntable to rotate in different ways, detect the rotation angular velocity using the target gyro, and calibrate the scale coefficient of the target gyro based on the comparison result between the gyro detection speed and the actual speed of the turntable; The addition table coefficient calibration unit is used to control the target turntable to be indexed according to different static modes, use the target addition table to detect the gravity acceleration in each static state, and calibrate the scale coefficient of the target addition table based on the comparison result between the addition table detection speed and the actual speed of the turntable; An error parameter calibration unit is used to implement a three-axis rotation excitation on the target turntable, take an IMU error parameter as a state variable to be estimated, take a velocity error as an observation, and estimate and calibrate the IMU error parameter, wherein the IMU error parameter includes relevant parameters that cause IMU detection errors; The zero bias parameter calibration unit is used to implement a rotation excitation based on the azimuth axis among the three axes on the target turntable, and estimate and calibrate the IMU zero bias parameters using the IMU zero bias parameters as the state variables to be estimated and the velocity error as the observed quantity.

9. An electronic device, characterized in that: include: Processor, memory; The memory is used to store computer programs; The processor is used to execute the calibration method of the inertial measurement unit according to any one of claims 1 to 7 by calling the computer program.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the calibration method of the inertial measurement unit described in any one of claims 1 to 7 is implemented.

Images