Inertial measurement unit calibration method and device, computer device and storage medium

Abstract

This invention provides an inertial measurement unit (IMU) calibration method, apparatus, computer equipment, and storage medium. The IMU calibration method includes: acquiring the gyro angular velocities along each of the three orthogonal axes of the IMU rotating along a hexahedral fixture; calculating the coupling error coefficient and scaling factor of the gyro along each axis based on the gyro angular velocities and environmental parameters; acquiring the position measurement values ​​output by the gyro along each axis and the position measurement values ​​output by the accelerometer along each axis at a preset rotation position of the IMU on the hexahedral fixture; calculating the zero-position deviation of the gyro along each axis based on the position measurement values, coupling error coefficient, and scaling factor; and calculating the coupling error coefficient, scaling factor, and zero-position deviation of the accelerometer along each axis based on the position measurement values ​​output by the accelerometer. This method achieves the technical requirements of simple installation of the calibration fixture and strong versatility of the calibration method.

Description

Technical Field

[0001] The present invention relates to the field of inertial measurement technology, and in particular to an inertial measurement unit calibration method, apparatus, computer equipment and storage medium. Background Technology

[0002] In the design and development of the Inertial Measurement Unit (IMU), the installation of the three gyroscopes and three accelerometers follows the principle that the sensitive axes of the three instruments are perpendicular to each other. The resulting coordinate system is called the instrument system, denoted by Oxyz. The IMU is mounted on the missile body primarily to measure the missile's angular and linear motion in three directions during flight: longitudinal, normal, and lateral. A coordinate system typically chosen is OXYZ (upper right front). Generally, the Oxyz and OXYZ coordinate axes are kept parallel to each other in the design. However, errors are inevitable from manufacturing to installation. Eliminating these errors requires system calibration.

[0003] Existing calibration methods are all based on three-axis turntables, which are expensive, have complex installation requirements, and have poor versatility, making them unsuitable for different IMUs. They also require a high level of manual operation skills and experience from the operators. Summary of the Invention

[0004] This application provides an inertial measurement unit (IMU) calibration method, apparatus, computer equipment, and storage medium to solve the technical problems of existing three-axis rotary tables being expensive, having complex installation requirements, poor universality of calibration methods, being unable to adapt to different IMUs, and requiring high manual operation skills and experience from operators.

[0005] The first aspect of this invention provides a calibration method for an inertial measurement unit (IMU). The IMU includes a gyroscope and an accelerometer. The IMU is fixed in a hexahedral fixture, which is mounted on a platform. The normal vector of the platform coincides with the celestial component of the Earth's rotation angular rate. The method includes: acquiring the gyroscope angular rates along each of the three orthogonal axes of the IMU as it rotates along the hexahedral fixture; calculating the coupling error coefficient and scaling factor of the gyroscope along each axis based on the gyroscope angular rates and environmental parameters, wherein the environmental parameters include the Earth's rotation angular rate and the geographic latitude under the current calibration environment; acquiring the position measurement values ​​output by the gyroscope and the position measurement values ​​output by the accelerometer along each axis at a preset rotation position of the IMU on the hexahedral fixture; calculating the zero-position deviation of the gyroscope along each axis based on the position measurement values ​​output by the gyroscope, the coupling error coefficient, and the scaling factor; and calculating the coupling error coefficient, scaling factor, and zero-position deviation of the accelerometer along each axis based on the position measurement values ​​output by the accelerometer.

[0006] The inertial measurement unit (IMU) calibration method provided in this invention does not require expensive high-precision three-axis turntables or other rate turntables. It utilizes a regular hexahedron—which is simple in design, small in size, low in cost, and easy to install and operate—as the mounting base for the IMU. The calibration of the gyroscope and accelerometer can be completed using a marble platform. This method is independent of rotational speed errors, avoiding the influence of these errors on the calibration results. By providing the IMU with a certain angular rate excitation, various gyroscope parameters can be calculated based on the gyroscope's output error model. Furthermore, this calibration method, while meeting calibration accuracy requirements, is highly versatile, has a high success rate, enables rapid IMU calibration, and has low dependence on the operator's experience and skills.

[0007] Optionally, it includes: obtaining a first conversion matrix based on the coupling error coefficients of the gyroscopes in each axis, the first conversion matrix being used for the conversion from the instrument system to the projectile system; and obtaining a second conversion matrix based on the coupling error coefficients of the accelerometers in each axis, the second conversion matrix being used for the conversion from the instrument system to the projectile system.

[0008] Optionally, obtaining the gyro angular rate in each axis when the inertial measurement unit rotates along the three orthogonal axes of the hexahedral tool includes: responding to a timing operation when the inertial measurement unit rotates along any one of the three orthogonal axes of the hexahedral tool; obtaining the sum of the angular rates in the corresponding axis when rotating along the corresponding axis of the hexahedral tool within a preset time period; obtaining the average angle rate based on the sum of the angular rates, and using the average angle rate as the gyro angular rate in the corresponding axis.

[0009] Optionally, acquiring the angular velocities of the gyroscopes along each of the three orthogonal axes of the hexahedral fixture includes: acquiring the angular velocities of the gyroscopes along each of the axes when the inertial measurement unit rotates along the X-axis of the hexahedral fixture, wherein the X-axis of the hexahedral fixture coincides with the celestial component of the Earth's rotation angular rate; acquiring the angular velocities of the gyroscopes along each of the axes when the inertial measurement unit rotates along the Y-axis of the hexahedral fixture, wherein the Y-axis of the hexahedral fixture coincides with the celestial component of the Earth's rotation angular rate; and acquiring the angular velocities of the gyroscopes along each of the axes when the inertial measurement unit rotates along the Z-axis of the hexahedral fixture, wherein the Z-axis of the hexahedral fixture coincides with the celestial component of the Earth's rotation angular rate.

[0010] Optionally, rotation along the three orthogonal axes of the hexahedral tooling includes counterclockwise rotation and clockwise rotation.

[0011] Optionally, a reference surface is provided on the platform, which is perpendicular to the platform. Environmental parameters also include the angle between the reference surface and the target geographic orientation. The zero-position deviation of the gyroscope in each axis is calculated based on the position measurement value output by the gyroscope, the coupling error coefficient, and the scaling factor. This includes: calculating the zero-position deviation of the gyroscope in each axis based on the position measurement value output by the gyroscope, the coupling error coefficient, the scaling factor, and the angle between the reference surface and the target geographic orientation.

[0012] Optionally, the gyroscope is a microelectromechanical system (MEMS) gyroscope.

[0013] A second aspect of the present invention provides an apparatus for calibrating an inertial measurement unit (IMU). The IMU includes a gyroscope and an accelerometer. The IMU is fixed in a hexahedral fixture, which is mounted on a platform. The normal vector of the platform coincides with the celestial component of the Earth's rotation angular rate. The apparatus includes: a first acquisition module for acquiring the gyroscope angular rates along each of the three orthogonal axes of the IMU as it rotates along the hexahedral fixture; and a first calculation module for calculating the coupling error coefficient and scaling factor of the gyroscope along each axis based on the gyroscope angular rates and environmental parameters. The environmental parameters include the Earth's rotation angular rate and the geographical latitude under the current calibration environment; the second acquisition module is used to acquire the position measurement values ​​output by the gyroscopes in each axis and the position measurement values ​​output by the accelerometers in each axis corresponding to the preset rotation position of the inertial measurement unit on the hexahedral tooling; the second calculation module is used to calculate the zero-position deviation of the gyroscopes in each axis based on the position measurement values ​​output by the gyroscopes, the coupling error coefficient, and the scaling factor; the third calculation module is used to calculate the coupling error coefficient, scaling factor, and zero-position deviation of the accelerometers in each axis based on the position measurement values ​​output by the accelerometers.

[0014] The functions performed by each component in the inertial measurement unit calibration device provided by the present invention have been applied in any of the method embodiments of the first aspect described above, and therefore will not be repeated here.

[0015] A third aspect of the present invention provides a computer device, including a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus; the memory is used to store computer programs; and the processor is used to implement the steps of the inertial measurement unit calibration method of the first aspect when executing the program stored in the memory.

[0016] A fourth aspect of the present invention provides a computer-readable storage medium storing computer instructions for causing a computer to perform an inertial measurement unit calibration method as provided in the first aspect of the present invention. Attached Figure Description

[0017] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of coordinate system transformation in an inertial measurement unit calibration method according to an embodiment of the present invention;

[0019] Figure 2 This is a schematic flowchart of an inertial measurement unit calibration method according to an embodiment of the present invention;

[0020] Figure 3 This is a schematic diagram corresponding to an inertial measurement unit calibration method provided in an embodiment of the present invention;

[0021] Figure 4 This is a schematic diagram corresponding to an inertial measurement unit calibration method provided in an embodiment of the present invention;

[0022] Figure 5 This is a schematic diagram corresponding to an inertial measurement unit calibration method provided in an embodiment of the present invention;

[0023] Figure 6 This is a schematic diagram of an inertial measurement unit calibration device provided in an embodiment of the present invention;

[0024] Figure 7 This is a schematic diagram of a computer device structure provided for an embodiment of the present invention. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0026] Unless otherwise defined, the technical or scientific terms used in this disclosure shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms “a,” “an,” or “the,” as used in this disclosure, do not indicate a limitation of quantity, but rather indicate the presence of at least one. Terms such as “comprising” or “including” mean that an element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects.

[0027] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0028] To address the technical problems mentioned in the background section, this invention provides a method for calibrating an inertial measurement unit (IMU). The IMU includes a gyroscope and an accelerometer. The polarity of the gyroscope is as follows: when the projectile rotates counterclockwise along each axis, the gyroscope outputs a positive value; when it rotates clockwise along each axis, the gyroscope outputs a negative value. The magnitude of the rotational angular rate is directly proportional to the magnitude of the gyroscope's output value.

[0029] The polarity of the accelerometer is as follows: when the carrier undergoes linear acceleration along the positive direction of each axis, the accelerometer outputs a positive value; when the carrier undergoes linear acceleration along the negative direction of each axis, the accelerometer outputs a negative value; the magnitude of the carrier's linear acceleration is directly proportional to the value output by the accelerometer.

[0030] Taking an inertial measurement unit (IMU) consisting of three gyroscopes and three accelerometers as an example, when the IMU is used, such as on a missile, the calculation formulas for obtaining the three angular velocities and three accelerations are as follows:

[0031] Three angular velocities ω X ω Y ω Z :

[0032]

[0033] in These are the parameters that need to be determined through calibration. ω x ω y ω z The gyroscope senses the angular velocities of the projectile in three directions, while real-time flight control requires ω. X ω Y ω Z The result is obtained through calculation using the above equation.

[0034]

[0035] This is the transformation matrix from the gyroscope instrument system Oxyz to the spring system OXYZ. For example... Figure 1 As shown, the coordinate systems are Oxyz (instrument coordinate system) and OXYZ (projectile coordinate system).

[0036] Three accelerations a X a Y a Z :

[0037]

[0038] in These are the parameters that need to be determined through calibration. x a y a z The accelerometer senses the acceleration of the projectile in three directions, while flight control requires a in real time. X a Y a Z The result is obtained through calculation using the above equation.

[0039]

[0040] This is the transformation matrix from the accelerometer instrument system Oxyz to the projectile system OXYZ. For example... Figure 1 As shown.

[0041] The transformation matrix, scaling factor, and zero-point deviation required in the calculation formulas for the three angular velocities and three accelerations needed by the inertial measurement unit (IMU) need to be obtained by calibrating the IMU. The calibration process is based on the gyroscope error model and the accelerometer error model.

[0042] The gyroscope error model can be written in matrix equation form as follows:

[0043]

[0044] Among them, G x G y G z The gyroscopes mounted along the x, y, and z axes of the instrument system output values ​​over time T (the sum or average of the angular velocities output within each period T); ω is set. X ω Y ω Z Let E be the excitation input of the actual calibrated time-launch system, and T be the set sampling time. The matrix E in (1.1) and (2.1) g They are inverses of each other and also transposes of each other.

[0045] The scale factor for the three gyroscopes; Zero-position deviation of the three gyroscopes; This represents the coupling error coefficient.

[0046] The accelerometer error model can be written in matrix equation form as follows:

[0047]

[0048] Among them, A x A y A zAccelerometers mounted along the x, y, and z axes of the instrument system output values ​​over time T (the sum or average of the acceleration values ​​output within each sampling period T); set a X a Y a Z Let E be the excitation input of the actual calibrated time-launch system, and T be the set sampling time. Matrix E in (1.2) and (2.2) a They are inverses of each other and also transposes of each other.

[0049] The scale factor for the three accelerometers; Zero bias of the three accelerometers; This represents the coupling error coefficient.

[0050] After clarifying the parameters required for the conversion between the instrument system and the missile system, namely: the conversion matrix (the nine parameters that make up the matrix are also called coupling error coefficients), the scaling factor and zero-position deviation of each instrument, and their relationship with the gyroscope error model and the accelerometer error model.

[0051] During calibration, the embodiment provided in this solution fixes the inertial measurement unit in a hexahedral fixture, which is placed on a platform, such as a marble platform. The normal vector of the platform coincides with the celestial component of the Earth's rotation angular rate. Figure 2 As shown, the steps of this method include:

[0052] Step S110: Obtain the gyro angular rate along each axis when the inertial measurement unit rotates along the three orthogonal axes of the hexahedral tooling.

[0053] For example, in order to calibrate the gyroscope scaling factor in the IMU and the coupling error coefficient between different coordinate systems, it is necessary to input a certain angular rate excitation into the IMU (ω in Equation 2.1). X ω Y ω Z This angular rate can be dynamic, and the output of the gyroscope in the corresponding axis (x, y, z axis) of the instrument system is measured. Specifically, in this embodiment, taking a marble platform and a micro-electro-mechanical system (MEMS) gyroscope as an example, the dynamic angular rate is generated by rotating a regular hexahedron based on the calibration method of the marble platform.

[0054] Before calibration, the IMU is first fixed onto a regular hexahedron. The mounting area of ​​the IMU on the hexahedron has reference surfaces; generally, only two reference surfaces are needed. The IMU housing has two corresponding reference surfaces, typically its bottom and side surfaces. The IMU housing and the hexahedron fixture, fixed together, form the elastic system OXYZ. Then, the hexahedron is placed on a marble platform. A support reference surface is provided on the platform, perpendicular to the platform, ensuring that the direction of the IMU's calibration axis coincides with the celestial component of the Earth's rotation angular rate, and that the reference surface of the hexahedron is pressed against the support reference surface on the platform. During calibration, the positions of the three calibration axes X, Y, and Z, and the instrument output, are as follows: Figure 3 , 4 As shown in Figure 5. It should be noted that the hexahedron has multiple reference faces, each with a different function. Specifically, all six faces of the hexahedron can serve as reference faces, used to rest against the platform's reference surface or the platform itself; the area where the IMU is mounted on the hexahedron also has reference faces for installation. Further details will not be elaborated here.

[0055] The tooling can rotate along three orthogonal axes, including counterclockwise and clockwise rotation.

[0056] Taking the X-axis calibration as an example, the main calibration steps are as follows:

[0057] Counterclockwise rotation: Place the cube on the platform with the positive X-axis pointing upwards, meaning the X-axis of the cube fixture coincides with the celestial component of the Earth's rotation angular rate. When the inertial measurement unit (IMU) rotates along the X-axis of the cube fixture, a timing operation is initiated. Within the sampling time T, the cube is rotated uniformly counterclockwise by N·360° around the X-axis. The angular rates of the gyroscopes along each axis are acquired as the IMU rotates along the X-axis of the cube fixture. The sum of the three gyroscope angular rates is stored. During the rotation, the cube must not leave the horizontal surface of the marble. After the rotation is completed, the cube should be pressed against the reference surface on the platform.

[0058] Clockwise rotation: When the inertial measurement unit rotates along the X-axis of the hexahedral fixture, a timing operation is initiated. Within the sampling time T, the hexahedron is rotated uniformly N·360° clockwise around the X-axis. The angular velocities of the gyroscopes along each axis are acquired as the inertial measurement unit rotates along the X-axis of the hexahedral fixture. The sum of the three gyroscope angular velocities is stored. During the rotation, the cube must not leave the horizontal surface of the marble. After the rotation is completed, the cube should be pressed against the reference surface on the platform.

[0059] Similarly, the Y-axis and Z-axis were calibrated to obtain the test data for the Y-axis and Z-axis gyroscopes, respectively.

[0060] As an optional implementation, the average angle rate can be obtained by summing the angular rates, and the average angle rate can be used as the gyro angular rate on the corresponding axis. This will not be elaborated further here.

[0061] In the above N·360°, N represents the number of rotations and is a positive integer, such as N=4. The sampling time T can be adaptively set according to actual needs, such as 100 seconds.

[0062] Step S120: Based on the gyroscope angular rate and environmental parameters, calculate the coupling error coefficient and scaling factor of the gyroscope in each axis. The environmental parameters include the Earth's rotation angular rate and the geographic latitude under the current calibration environment.

[0063] For example, using ω e To represent the Earth's angular rate of rotation, ω e = 15.0411 degrees / hour; using This represents the geographical latitude under the current calibration environment. It should be noted that the Earth's rotational angular velocity ω... e The horizontal component, 15.0411 degrees / hour, is averaged out as the cube rotates N·360° around a certain axis. That is: Where Ω is the input angular rate (obtained by rotating a regular hexahedron); α is the angle between the reference surface on the platform and the geographical orientation of the target, which in this embodiment is the angle between the marble reference surface and the geographical north direction;

[0064] By calibrating the gyroscope's angular rate in step S110, the angular rate output by the gyroscope is obtained. With the positive X-axis pointing upwards, and the hexahedral fixture rotating counterclockwise (positive) and clockwise (negative) around the X-axis respectively, the following equation holds:

[0065]

[0066] From equation (3.1), we get:

[0067]

[0068]

[0069] After sorting, we can obtain:

[0070] With the Y-axis pointing upwards, when the hexahedral tool rotates counterclockwise (positive) and clockwise (negative) around the Y-axis, the following equation holds:

[0071]

[0072] From equation (3.3), we get:

[0073]

[0074]

[0075] Summarized as follows:

[0076] With the Z-axis of the elastic system pointing upwards, when the hexahedral tool rotates counterclockwise (positive) and clockwise (negative) around the Z-axis respectively, the following equation holds:

[0077]

[0078] From equation (3.5), we get:

[0079]

[0080]

[0081] Summarized as follows: because: From the sum of squares of (3.2), (3.4), and (3.6), we can rearrange to obtain:

[0082]

[0083] From (3.2), (3.4) and (3.6), we get:

[0084]

[0085] From (3.1), (3.3), and (3.5), after the same processing as described above, we have:

[0086] get:

[0087]

[0088] Furthermore:

[0089]

[0090] Similarly, we have:

[0091]

[0092] get:

[0093]

[0094] Furthermore:

[0095]

[0096] The first transformation matrix is ​​obtained based on the coupling error coefficients of the gyroscopes in each axis, which is used to realize the transformation from the gyroscope instrument system to the projectile system.

[0097]

[0098] Step S130: Obtain the position measurement values ​​of the gyroscope outputs on each axis and the position measurement values ​​of the accelerometer outputs on each axis corresponding to the preset indexing position of the inertial measurement unit on the hexahedral tooling.

[0099] For example, rotation refers to the different positions formed when the hexahedron is rotated and placed on a platform with different orientations for each axis of the projectile during position calibration. Preset rotation refers to the pre-setting of the position formed by rotating the hexahedron. Position measurement values ​​refer to the output values ​​of the gyroscope and accelerometer along each axis after the hexahedron is placed on the platform and left to stand still.

[0100] The speed calibration of the gyroscope was completed according to steps S110 to S120, and the gyroscope's velocity was extracted. Scale factors Coupling error coefficient.

[0101] Then, based on this, the position of the gyroscope and accelerometer is calibrated, and the zero-order term D of the gyroscope is extracted. gyro 0x D gyro 0y D gyro 0z and the zero term of the accelerometer scale factor and coupling error coefficient.

[0102] For position calibration, there are various calibration methods available, including but not limited to the six-position method and the eight-position method. In this embodiment, the preset rotation uses the six-position method as an example. These six positions are:

[0103] (1) South to the west (2) Southeast to the earth (3) North to the east

[0104] (4) Earth North East (5) North West Sky (6) West Earth South

[0105] It is important to emphasize that the X, Y, and Z axes must be aligned with the corresponding positional directions. For example, "South to the West" means that the positive X-axis points to "South", the positive Y-axis points to "Sky", and the positive Z-axis points to "West".

[0106] Zero-position calibration of the gyroscope:

[0107] Zero-position calibration of a gyroscope requires environmental parameters, including the angle α between the reference plane on the platform and the geographical location of the target, the local latitude φ, and the Earth's rotational speed ω. e The components along each axis of the instrument system are:

[0108]

[0109] Where e represents the x-axis component in the instrument system, n represents the y-axis component in the instrument system, and t represents the z-axis component in the instrument system.

[0110] Corresponding to the six preset positions, each position has a position measurement value relative to the x-axis gyroscope measurement output of the instrument system. (i = 1 South Sky West, 2 Southeast Earth, 3 Sky Northeast, 4 Earth North East, 5 North West Sky, 6 West Earth South).

[0111] Similarly:

[0112] Corresponding to the six preset positions, each position has a position measurement value output by the y-axis gyroscope under the instrument system. (i = 1 South Sky West, 2 Southeast Earth, 3 Sky Northeast, 4 Earth North East, 5 North West Sky, 6 West Earth South);

[0113] Corresponding to the six preset positions, each position has a position measurement value output from the z-axis gyroscope under the instrument system. (i = 1 South Sky West, 2 Southeast Earth, 3 Sky Northeast, 4 Earth North East, 5 North West Sky, 6 West Earth South).

[0114] During the six-position calibration of the gyroscope to its zero position, the position measurements related to the accelerometer were also determined:

[0115] The x-axis accelerometer measures the position value output by the accelerometer.

[0116] (i = 1 South Sky West, 2 Southeast Earth, 3 Sky Northeast, 4 Earth North East, 5 North West Sky, 6 West Earth South);

[0117] The position measurement value output by the y-axis accelerometer

[0118] (i = 1 South Sky West, 2 Southeast Earth, 3 Sky Northeast, 4 Earth North East, 5 North West Sky, 6 West Earth South);

[0119] The z-axis accelerometer measures the position value output.

[0120] (i = 1 South Sky West, 2 Southeast Earth, 3 Sky Northeast, 4 Earth North East, 5 North West Sky, 6 West Earth South).

[0121] Step S140: Calculate the zero-position deviation of the gyroscope in each axis based on the position measurement value output by the gyroscope, the coupling error coefficient, and the scaling factor.

[0122] Corresponding to the six flip positions, there is an equation for the x-axis gyroscope measurement output under the instrument system at each position, resulting in a total of six equations, which can be written in matrix form as shown in Equation 4.1:

[0123]

[0124] (i = 1 South Sky West, 2 Southeast Earth, 3 Sky Northeast, 4 Earth North East, 5 North West Sky, 6 West Earth South) represents the output of the x-axis gyroscope at each position within the sampling time T.

[0125] Summing both sides of the six equations in (4.1), we get:

[0126]

[0127] Corresponding to the six flip positions, there is an equation for the y-axis gyroscope measurement output under the instrument system at each position, resulting in a total of 6 equations, which can be written in matrix form as follows.

[0128]

[0129] (i = 1 South Sky West, 2 Southeast Earth, 3 Sky Northeast, 4 Earth North East, 5 North West Sky, 6 West Earth South) represents the output of the y-axis gyroscope at each position within the sampling time T;

[0130] Summing both sides of the six equations in (4.3), we get:

[0131]

[0132] Corresponding to the six flip positions, there is an equation for the z-axis gyroscope measurement output under the instrument system at each position, resulting in a total of 6 equations, which can be written in matrix form as follows.

[0133]

[0134] (i = 1 South Sky West, 2 Southeast Earth, 3 Sky Northeast, 4 Earth North East, 5 North West Sky, 6 West Earth South) represents the output of the z-axis gyroscope at each position within the sampling time T;

[0135] Summing both sides of the six equations in (4.5), we get:

[0136]

[0137] Step S150: Calculate the coupling error coefficient, scaling factor, and zero-position deviation of the accelerometers in each axis based on the position measurement values ​​output by the accelerometers.

[0138] For example, during the process of calibrating the gyroscope to zero position at six positions, all parameters related to the accelerometer are also determined.

[0139] In the six positions, the x-accelerometer measurement output is:

[0140]

[0141] (i = 1 South Sky West, 2 Southeast Earth, 3 Sky Northeast, 4 Earth North East, 5 North West Sky, 6 West Earth South) is the output of the sum of x-axis accelerometer values ​​at each position within the sampling time T, and g is the gravitational acceleration.

[0142] From (4.7), we can obtain:

[0143]

[0144]

[0145]

[0146] because:

[0147]

[0148] but:

[0149]

[0150] Therefore, we get:

[0151]

[0152] By adding both sides of the six equations in (4.7), we get:

[0153]

[0154] In the six positions, the y-accelerometer measurement output is:

[0155]

[0156] (i = 1 South Sky West, 2 Southeast Earth, 3 Sky Northeast, 4 Earth North East, 5 North West Sky, 6 West Earth South) represents the sum of the y-axis acceleration values ​​at each position within the sampling time T, where g is the gravitational acceleration. From (4.8), we can obtain:

[0157]

[0158] because:

[0159]

[0160] Then we have:

[0161]

[0162] Therefore, we get:

[0163]

[0164] By adding both sides of the six equations in (4.8), we get:

[0165]

[0166] In the six positions, the z-accelerometer measurement output is:

[0167]

[0168] (i = 1 South Sky West, 2 Southeast Earth, 3 Sky Northeast, 4 Earth North East, 5 North West Sky, 6 West Earth South) represents the sum of the z-axis acceleration values ​​at each position within the sampling time T, where g is the gravitational acceleration. From (4.9), we can obtain:

[0169]

[0170] because:

[0171]

[0172] Then we have:

[0173]

[0174] Therefore, we get:

[0175]

[0176] The second transformation matrix is ​​obtained based on the coupling error coefficients of the accelerometers in each axis, which is used to realize the transformation from the accelerometer instrument system to the projectile system.

[0177]

[0178] By adding both sides of the six equations in (4.9), we get:

[0179]

[0180] Therefore, under existing laboratory testing conditions, based on a regular hexahedron and platform, and through reasonable planning of the testing process, the instrument error compensation parameters required by the IMU can be obtained. The calibration parameter formulas obtained by this method are as follows:

[0181] 1) The parameters related to the three gyroscopes are: The specific calculations are as follows:

[0182]

[0183]

[0184]

[0185]

[0186]

[0187]

[0188]

[0189] 2) The parameters related to the three accelerometers are: The calculation formula is as follows:

[0190]

[0191]

[0192]

[0193]

[0194]

[0195]

[0196]

[0197]

[0198]

[0199] The inertial measurement unit (IMU) calibration method provided in this invention does not require expensive high-precision three-axis turntables or other rate turntables. It utilizes a regular hexahedron—which is simple in design, small in size, low in cost, and easy to install and operate—as the mounting base for the IMU. The calibration of the gyroscope and accelerometer can be completed using a marble platform. This method is independent of rotational speed errors, avoiding the influence of these errors on the calibration results. By providing the IMU with a certain angular rate excitation, various gyroscope parameters can be calculated based on the gyroscope's output error model. Furthermore, this calibration method, while meeting calibration accuracy requirements, is highly versatile, has a high success rate, enables rapid IMU calibration, and has low dependence on the operator's experience and skills.

[0200] Figure 6 An inertial measurement unit (IMU) calibration device is provided according to an embodiment of the present invention. The IMU includes a gyroscope and an accelerometer. The IMU is fixed in a hexahedral fixture, which is mounted on a platform. The normal vector of the platform coincides with the celestial component of the Earth's rotation angular rate. The device includes:

[0201] The first acquisition module 210 is used to acquire the gyro angular velocities along each axis obtained when the inertial measurement unit rotates along the three orthogonal axes of the hexahedral tooling. For details, please refer to the description of the corresponding steps in the above embodiments, which will not be repeated here.

[0202] The first calculation module 220 is used to calculate the coupling error coefficient and scaling factor of the gyroscope in each axis based on the gyroscope angular rate and environmental parameters. The environmental parameters include the Earth's rotation angular rate and the geographic latitude under the current calibration environment. For details, please refer to the description of the corresponding steps in the above embodiments, which will not be repeated here.

[0203] The second acquisition module 230 is used to acquire the position measurement values ​​output by the gyroscopes along each axis and the position measurement values ​​output by the accelerometers along each axis on the preset indexing position of the inertial measurement unit on the hexahedral tooling. For details, please refer to the description of the corresponding steps in the above embodiments, which will not be repeated here.

[0204] The second calculation module 240 is used to calculate the zero-position deviation of the gyroscope in each axis based on the position measurement value output by the gyroscope, the coupling error coefficient, and the scaling factor. For details, please refer to the description of the corresponding steps in the above embodiments, which will not be repeated here.

[0205] The third calculation module 250 is used to calculate the coupling error coefficient, scaling factor, and zero-position deviation of the accelerometers in each axis based on the position measurement values ​​output by the accelerometers. For details, please refer to the description of the corresponding steps in the above embodiments, which will not be repeated here.

[0206] As an optional embodiment of the present invention, it further includes:

[0207] The first construction module is used to obtain a first transformation matrix based on the coupling error coefficients of the gyroscopes in each axis. The first transformation matrix is ​​used for the transformation from the instrument system to the missile system. For details, please refer to the description of the corresponding steps in the above embodiments, which will not be repeated here.

[0208] The second construction module is used to obtain the second transformation matrix based on the coupling error coefficients of the accelerometers in each axis. The second transformation matrix is ​​used for the transformation from the instrument system to the projectile system. For details, please refer to the description of the corresponding steps in the above embodiments, which will not be repeated here.

[0209] As an optional embodiment of the present invention, the first acquisition module 210 includes:

[0210] The first timing submodule is used to respond to timing operations when the inertial measurement unit rotates along any one of the three orthogonal axes of the hexahedral tooling. For details, please refer to the description of the corresponding steps in the above embodiments, which will not be repeated here.

[0211] The first acquisition submodule is used to acquire the cumulative angular velocity along the corresponding axis when the hexahedral tool rotates within a preset time period. For details, please refer to the description of the corresponding steps in the above embodiments, which will not be repeated here.

[0212] The first calculation submodule is used to obtain the average angle rate based on the sum of the angular rates, and then use the average angle rate as the gyro angular rate along the corresponding axis. For details, please refer to the description of the corresponding steps in the above embodiments, which will not be repeated here.

[0213] As an optional embodiment of the present invention, the first acquisition module 210 includes:

[0214] The second acquisition submodule is used to acquire the angular velocities of the gyroscopes along each axis obtained when the inertial measurement unit rotates along the X-axis of the hexahedral fixture, wherein the X-axis of the hexahedral fixture coincides with the celestial component of the Earth's rotation angular rate. For details, please refer to the description of the corresponding steps in the above embodiments, which will not be repeated here.

[0215] The third acquisition submodule is used to acquire the angular velocities of the gyroscopes along each axis obtained when the inertial measurement unit rotates along the Y-axis of the hexahedral fixture, wherein the Y-axis of the hexahedral fixture coincides with the celestial component of the Earth's rotation angular rate. For details, please refer to the description of the corresponding steps in the above embodiments, which will not be repeated here.

[0216] The fourth acquisition submodule is used to acquire the angular velocities of the gyroscopes along each axis obtained when the inertial measurement unit rotates along the Z-axis of the hexahedral fixture, wherein the Z-axis of the hexahedral fixture coincides with the celestial component of the Earth's rotation angular rate. For details, please refer to the descriptions of the corresponding steps in the above embodiments, which will not be repeated here.

[0217] As an optional embodiment of the present invention, the device includes: rotating along three orthogonal axes of the hexahedral tool, including counterclockwise rotation and clockwise rotation. For details, please refer to the description of the corresponding steps in the above embodiments, which will not be repeated here.

[0218] As an optional embodiment of the present invention, a bearing reference surface is provided on the platform, the bearing reference surface is perpendicular to the platform, and the environmental parameters also include the angle between the bearing reference surface and the target geographical orientation; the second calculation module 240 includes:

[0219] The second calculation submodule is used to calculate the zero-position deviation of the gyroscope in each axis based on the position measurement value output by the gyroscope, the coupling error coefficient, the scaling factor, and the angle between the reference plane and the geographical orientation of the target. For details, please refer to the description of the corresponding steps in the above embodiments, which will not be repeated here.

[0220] As an optional embodiment of the present invention, the device includes: the gyroscope is a microelectromechanical system gyroscope.

[0221] This invention provides a computer device, such as... Figure 7 As shown, the device includes one or more processors 810 and a memory 820, the memory 820 including persistent memory, volatile memory, and a hard disk. Figure 7 Taking a processor 810 as an example, the device may also include an input device 830 and an output device 840.

[0222] The processor 810, memory 820, input device 830, and output device 840 can be connected via a bus or other means. Figure 7 Taking the example of a connection between China and Israel via a bus.

[0223] Processor 810 may be a Central Processing Unit (CPU). Processor 810 may also be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or combinations thereof. The general-purpose processor may be a microprocessor or any conventional processor. Memory 820 may include a program storage area and a data storage area. The program storage area may store the operating system and at least one application program required for a function; the data storage area may store data created based on the use of the inertial measurement unit calibration device. Furthermore, memory 820 may include high-speed random access memory and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some embodiments, memory 820 may optionally include memories remotely located relative to processor 810, which can be connected to the inertial measurement unit calibration device via a network. The input device 830 can receive calculation requests (or other numerical or character information) input by the user, and generate key signal inputs related to the inertial measurement unit calibration device. The output device 840 may include a display screen or other display device for outputting the calculation results.

[0224] This invention provides a computer-readable storage medium that stores computer instructions. The computer storage medium stores computer-executable instructions that can execute the inertial measurement unit calibration method described in any of the above-described method embodiments. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk drive (HDD), or solid-state drive (SSD), etc.; the storage medium may also include combinations of the above types of memory.

[0225] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable storage medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable storage medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable storage media include: electrical connections (electronic devices) having one or more wires, portable computer disk drives (magnetic devices), random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), fiber optic devices, and compact disc read-only memory (CDROM). Furthermore, computer-readable storage media can even be paper or other suitable media on which programs can be printed, because programs can be obtained electronically, for example, by optically scanning the paper or other media, followed by editing, interpreting, or otherwise processing as necessary, and then stored in computer memory.

[0226] It should be understood that various parts of this disclosure can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0227] In the description of this specification, the references to terms such as "this embodiment," "an embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this disclosure. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples, without contradiction. In the description of this disclosure, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0228] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for calibrating an inertial measurement unit (IMU), the IMU comprising a gyroscope and an accelerometer, the IMU being fixed in a hexahedral fixture, the hexahedral fixture being mounted on a platform, the normal vector of the platform coinciding with the celestial component of the Earth's rotation angular rate; characterized in that, The method includes: The gyro angular velocities along each axis are obtained when the inertial measurement unit rotates along the three orthogonal axes of the hexahedral tooling. Based on the gyroscope angular rate and environmental parameters, the coupling error coefficient and scaling factor of the gyroscope in each axis are calculated, wherein the environmental parameters include the Earth's rotation angular rate and the geographic latitude under the current calibration environment; Acquire the position measurement values ​​of the gyroscope outputs in each axis and the position measurement values ​​of the accelerometer outputs in each axis on the preset indexing position of the inertial measurement unit on the hexahedral tooling; The zero-position deviation of the gyroscope in each axis is calculated based on the position measurement value output by the gyroscope, the coupling error coefficient, and the scaling factor. Calculate the coupling error coefficient, scale factor, and zero-position deviation of the accelerometers in each axis based on the position measurement values ​​output by the accelerometers; The acquisition of the gyro angular velocities along each axis obtained when the inertial measurement unit rotates along the three orthogonal axes of the hexahedral tooling includes: When the inertial measurement unit rotates along any one of the three orthogonal axes of the hexahedral tooling, a timing operation is initiated; the sum of the angular rates along the corresponding axis during rotation within a preset time period is obtained; the average angle rate is obtained based on the sum of the angular rates, and the average angle rate is used as the gyro angular rate along the corresponding axis. Alternatively, obtain the angular velocities of the gyroscopes along each axis when the inertial measurement unit rotates along the X-axis of the hexahedral fixture, wherein the X-axis of the hexahedral fixture coincides with the celestial component of the Earth's rotation angular rate; obtain the angular velocities of the gyroscopes along each axis when the inertial measurement unit rotates along the Y-axis of the hexahedral fixture, wherein the Y-axis of the hexahedral fixture coincides with the celestial component of the Earth's rotation angular rate; obtain the angular velocities of the gyroscopes along each axis when the inertial measurement unit rotates along the Z-axis of the hexahedral fixture, wherein the Z-axis of the hexahedral fixture coincides with the celestial component of the Earth's rotation angular rate.

2. The inertial measurement unit calibration method according to claim 1, characterized in that, Also includes: The first transformation matrix is ​​obtained based on the coupling error coefficients of the gyroscopes in each axis. The first transformation matrix is ​​used for the transformation from the instrument system to the missile system. The second transformation matrix is ​​obtained based on the coupling error coefficients of the accelerometers in each axis. The second transformation matrix is ​​used for the transformation from the instrument system to the projectile system.

3. The inertial measurement unit calibration method according to claim 1, characterized in that, The rotation along the three orthogonal axes of the hexahedral tooling includes counterclockwise rotation and clockwise rotation.

4. The inertial measurement unit calibration method according to claim 1, characterized in that, A reference surface is provided on the platform, which is perpendicular to the platform. The environmental parameters also include the angle between the reference surface and the target geographical location. The calculation of the zero-position deviation of the gyroscope in each axis based on the position measurement value output by the gyroscope, the coupling error coefficient, and the scaling factor includes: The zero-position deviation of the gyroscope in each axis is calculated based on the position measurement value output by the gyroscope, the coupling error coefficient, the scaling factor, and the angle between the reference plane and the geographical orientation of the target.

5. The inertial measurement unit calibration method according to claim 1, characterized in that, The gyroscope is a microelectromechanical system (MEMS) gyroscope.

6. An inertial measurement unit (IMU) calibration device, wherein the IMU comprises a gyroscope and an accelerometer, the IMU is fixed in a hexahedral fixture, the hexahedral fixture is mounted on a platform, and the normal vector of the platform coincides with the celestial component of the Earth's rotation angular rate; characterized in that, include: The first acquisition module is used to acquire the gyro angular rate in each axis when the inertial measurement unit rotates along the three orthogonal axes of the hexahedral tooling. The first calculation module is used to calculate the coupling error coefficient and scaling factor of the gyroscope in each axis based on the gyroscope angular rate and environmental parameters, wherein the environmental parameters include the Earth's rotation angular rate and the geographical latitude under the current calibration environment; The second acquisition module is used to acquire the position measurement values ​​of the gyroscope outputs in each axis and the position measurement values ​​of the accelerometer outputs in each axis corresponding to the preset indexing position of the inertial measurement unit on the hexahedral tooling. The second calculation module is used to calculate the zero-position deviation of the gyroscope in each axis based on the position measurement value output by the gyroscope, the coupling error coefficient, and the scaling factor. The third calculation module is used to calculate the coupling error coefficient, scale factor and zero-position deviation of the accelerometers in each axis based on the position measurement values ​​output by the accelerometers. The first acquisition module is specifically used for: When the inertial measurement unit rotates along any one of the three orthogonal axes of the hexahedral tooling, a timing operation is initiated; the sum of the angular rates along the corresponding axis during rotation within a preset time period is obtained; the average angle rate is obtained based on the sum of the angular rates, and the average angle rate is used as the gyro angular rate along the corresponding axis. or, The angular velocities of the gyroscopes along each axis are obtained when the inertial measurement unit rotates along the X-axis of the hexahedral fixture, wherein the X-axis of the hexahedral fixture coincides with the celestial component of the Earth's rotation angular rate; the angular velocities of the gyroscopes along each axis are obtained when the inertial measurement unit rotates along the Y-axis of the hexahedral fixture, wherein the Y-axis of the hexahedral fixture coincides with the celestial component of the Earth's rotation angular rate; the angular velocities of the gyroscopes along each axis are obtained when the inertial measurement unit rotates along the Z-axis of the hexahedral fixture, wherein the Z-axis of the hexahedral fixture coincides with the celestial component of the Earth's rotation angular rate.

7. A computer device, characterized in that, It includes a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus; Memory, used to store computer programs; When a processor executes a program stored in a memory, it implements the steps of the inertial measurement unit calibration method according to any one of claims 1-5.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the inertial measurement unit calibration method as described in any one of claims 1-5.

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