CN115931001A - Inertial measurement unit calibration method and device, computer equipment and storage medium - Google Patents
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Abstract
The invention provides a calibration method and a calibration device for an inertial measurement unit, computer equipment and a storage medium, wherein the calibration method for the inertial measurement unit comprises the following steps: acquiring gyro angular rates in all axial directions, which are obtained when an inertia measurement unit rotates along three orthogonal axial directions of a regular hexahedron tool; calculating coupling error coefficients and scale factors of the gyroscope in each axial direction based on the angular rate of the gyroscope and the environmental parameters; obtaining position measurement values output by gyros in all axial directions and position measurement values output by accelerometers in all axial directions, which correspond to the inertia measurement unit on the preset transposition of the regular hexahedron tool; calculating the zero offset of the gyroscope in each axial direction based on the position measurement value, the coupling error coefficient and the scale factor output by the gyroscope; coupling error coefficients, scaling factors and zero offset of the accelerometers in each axis are calculated based on position measurements output by the accelerometers. The calibration tool is simple to install, and the calibration method meets the technical requirement of high universality.
Description
Technical Field
The embodiment of the invention relates to the technical field of inertial measurement, in particular to a calibration method and device of an inertial measurement unit, computer equipment and a storage medium.
Background
In the design development of an Inertial Measurement Unit (IMU), three gyros and three accelerometers are all installed according to the principle that the sensitive axes of the three accelerometers are perpendicular to each other, and the coordinate system formed by the three gyros is called an instrument system and is expressed by Oxyz. The IMU is arranged on the projectile body and is mainly used for measuring angular motion and linear motion of the projectile body in three directions in flight, wherein the three directions are the longitudinal direction, the normal direction and the transverse direction of the projectile body respectively, and a coordinate system is usually selected for the front upper and the right and is expressed by OXYZ. Generally, the coordinate axes of Oxyz and xyz are kept parallel to each other in the design, but errors are inevitably generated from machining to mounting. This "elimination" of error requires system calibration to account for.
The existing calibration method is based on a three-axis turntable, the three-axis turntable is expensive, the installation requirement is complex, the calibration method is poor in universality, cannot adapt to different IMUs, and has high requirements on manual operation capability and experience of operators.
Disclosure of Invention
The application provides an inertial measurement unit calibration method, an inertial measurement unit calibration device, computer equipment and a storage medium, and aims to solve the technical problems that a three-axis turntable in the prior art is expensive, installation requirements are complex, the calibration method is poor in universality, cannot adapt to different IMUs, and has high requirements on manual operation capacity and experience of operators.
The invention provides a first aspect of a method for calibrating an inertia measurement unit, wherein the inertia measurement unit comprises a gyroscope and an accelerometer, the inertia measurement unit is fixed in a regular hexahedron tool, the regular hexahedron tool is arranged on a platform, and a normal vector of the platform is superposed with the direction of the natural angular velocity sky component of the earth, and the method comprises the following steps: acquiring gyro angular rates in all axial directions, which are obtained when an inertia measurement unit rotates along three orthogonal axial directions of a regular hexahedron tool; calculating coupling error coefficients and scale factors of the gyroscope in each axial direction based on the angular rate of the gyroscope and environmental parameters, wherein the environmental parameters comprise the rotation angular rate of the earth and the geographic latitude under the current calibration environment; acquiring position measurement values output by gyros in all axial directions and position measurement values output by accelerometers in all axial directions, which correspond to the inertia measurement unit on the preset transposition of the regular hexahedron tool; calculating the zero offset of the gyroscope in each axial direction based on the position measurement value output by the gyroscope, the coupling error coefficient and the scale factor; coupling error coefficients, scaling factors and zero offset of the accelerometers in each axis are calculated based on position measurements output by the accelerometers.
According to the inertial measurement unit calibration method provided by the embodiment of the invention, an expensive high-precision three-axis turntable or other rate turntables are not needed, a regular hexahedron with the advantages of simple design, small volume, low cost, simplicity in installation, simplicity in operation and the like is used as a mounting base of the inertial measurement unit, the gyroscope and an accelerometer can be calibrated by means of a marble platform, the method is irrelevant to a rotation speed error, the influence of the rotation speed error on a calibration result is avoided, a certain angular rate excitation is given to an IMU, and various indexes of the gyroscope can be calculated according to an output error model of the gyroscope. Meanwhile, the calibration method has strong universality and high calibration success rate on the premise of meeting the calibration precision, can realize quick calibration of the IMU, and has lower dependence on experience and capability of operators.
Optionally, comprising: obtaining a first conversion matrix according to the coupling error coefficient of the gyroscope in each axial direction, wherein the first conversion matrix is used for converting an instrument system into a bomb system; and obtaining a second conversion matrix according to the coupling error coefficient of the accelerometer in each axial direction, wherein the second conversion matrix is used for converting the instrument system into the bomb system.
Optionally, obtaining the gyro angular rate in each axial direction obtained when the inertia measurement unit rotates along three orthogonal axial directions of the regular hexahedron tool includes: when the inertia measuring unit rotates along any orthogonal axis of the three orthogonal axes of the regular hexahedron tool, timing operation is responded; acquiring angular rate accumulation in the corresponding axial direction when the regular hexahedron tool rotates along the corresponding axial direction within a preset time; and obtaining an angle rate average value based on the angular rate accumulation sum, and taking the angle rate average value as the gyro angular rate in the corresponding axial direction.
Optionally, obtaining the gyro angular rate in each axial direction obtained when the inertia measurement unit rotates along three orthogonal axial directions of the regular hexahedron tool includes: obtaining angular rates of the gyros in all axial directions, which are obtained when the inertia measurement unit rotates along the X axial direction of the regular hexahedron tool, wherein the X axial direction of the regular hexahedron tool is superposed with the direction of the natural component of the angular rate of rotation of the earth; obtaining the angular rate of the gyroscope in each axial direction obtained when the inertia measurement unit rotates along the Y axial direction of the regular hexahedron tool, wherein the Y axis of the regular hexahedron tool is superposed with the direction of the natural component of the earth rotation angular rate; and acquiring the angular rate of the gyroscope in each axial direction, which is obtained when the inertia measurement unit rotates along the Z axial direction of the regular hexahedron tool, wherein the Z axial direction of the regular hexahedron tool is superposed with the direction of the natural component of the angular rate of the earth.
Optionally, the rotation along three orthogonal axial directions of the regular hexahedron tool includes rotation along a counterclockwise direction and rotation along a clockwise direction.
Optionally, a bearing reference surface is arranged on the platform, the bearing reference surface is perpendicular to the platform, and the environmental parameters further include an included angle between the bearing reference surface and the target geographic position; calculating the zero offset of the gyroscope in each axial direction based on the position measurement value, the coupling error coefficient and the scale factor output by the gyroscope, and comprising the following steps: and calculating the zero offset of the gyroscope in each axial direction based on the position measurement value output by the gyroscope, the coupling error coefficient, the scale factor and the included angle between the bearing reference surface and the target geographic orientation.
Optionally, the gyroscope is a microelectromechanical system gyroscope.
The invention provides a device for calibrating an inertia measurement unit, wherein the inertia measurement unit comprises a gyroscope and an accelerometer, the inertia measurement unit is fixed in a regular hexahedron tool, the regular hexahedron tool is arranged on a platform, and a normal vector of the platform is superposed with the direction of the natural angular velocity sky component of the earth; the method comprises the following steps: the first acquisition module is used for acquiring gyro angular rates in all axial directions, which are obtained when the inertia measurement unit rotates along three orthogonal axial directions of the regular hexahedron tool; the first calculation module is used for calculating coupling error coefficients and scale factors of the gyroscope in each axial direction based on the angular rate of the gyroscope and environmental parameters, wherein the environmental parameters comprise the rotation angular rate of the earth and the geographic latitude under the current calibration environment; the second acquisition module is used for acquiring position measurement values output by the gyroscope in each axial direction and position measurement values output by the accelerometers in each axial direction, which correspond to the inertial measurement unit on the preset transposition of the regular hexahedral tool; the second calculation module is used for calculating the zero offset of the gyroscope in each axial direction based on the position measurement value output by the gyroscope, the coupling error coefficient and the scale factor; and the third calculation module is used for calculating the coupling error coefficient, the scaling factor and the zero offset of the accelerometers in each axial direction based on the position measurement values output by the accelerometers.
The functions performed by the components in the calibration apparatus for an inertial measurement unit according to the present invention are all applied to any of the embodiments of the method according to the first aspect, and therefore, are not described herein again.
The third aspect of the present invention provides a computer device, which comprises a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory complete mutual communication through the communication bus; a memory for storing a computer program; and a processor, configured to implement the steps of the calibration method for an inertial measurement unit according to the first aspect when executing the program stored in the memory.
A fourth aspect of the present invention provides a computer-readable storage medium storing computer instructions for causing a computer to execute the method for calibrating an inertial measurement unit as provided in the first aspect of the present invention.
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In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
Fig. 1 is a schematic diagram of coordinate system transformation of an inertial measurement unit calibration method according to an embodiment of the present invention;
FIG. 2 is a schematic flow chart illustrating a calibration method for an inertial measurement unit according to an embodiment of the present invention;
fig. 3 is a schematic diagram corresponding to a calibration method for an inertial measurement unit according to an embodiment of the present invention;
fig. 4 is a schematic diagram corresponding to a calibration method for an inertial measurement unit according to an embodiment of the present invention;
fig. 5 is a schematic diagram corresponding to a calibration method for an inertial measurement unit according to an embodiment of the present invention;
fig. 6 is a schematic structural diagram of an inertial measurement unit calibration apparatus according to an embodiment of the present invention;
fig. 7 is a schematic structural diagram of a computer device according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present disclosure more apparent, the technical solutions of the embodiments of the present disclosure will be described clearly and completely with reference to the drawings of the embodiments of the present disclosure. It is to be understood that the described embodiments are only a few embodiments of the present disclosure, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the disclosure without inventive step, are within the scope of protection of the disclosure.
Unless otherwise defined, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this disclosure belongs. The use of "a," "an," or "the" and similar words in this disclosure also does not imply a limitation on the number, but rather the presence of at least one. The word "comprising" or "comprises", and the like, means that the element or item listed before the word covers the element or item listed after the word and its equivalents, but does not exclude other elements or items.
In addition, the technical features involved in the different embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
In view of the technical problems mentioned in the background art, an embodiment of the present invention provides a calibration method for an inertial measurement unit, where the inertial measurement unit includes a gyroscope and an accelerometer, and the gyroscope has a polarity: when the projectile body rotates anticlockwise along each axis in the positive direction, the gyroscope outputs a positive value; when the gyroscope rotates clockwise along each axis, the gyroscope outputs a negative value. The magnitude of the rotation angular rate is proportional to the magnitude of the gyro output.
The accelerometer polarity is: when the carrier does linear accelerated motion along the positive direction of each shaft, the accelerometer outputs a positive value; when the carrier does linear accelerated motion along the negative direction of each shaft, the accelerometer outputs a negative value; the magnitude of the accelerated motion of the carrier line is proportional to the value output by the accelerometer.
Taking the inertial measurement unit including three gyros and three accelerometers as an example, when the inertial measurement unit is applied, for example, when the inertial measurement unit is applied to a missile, the required three angular rates and three acceleration information are obtained and calculated according to the following formulas:
three angular rates omega X 、ω Y 、ω Z ：
Wherein
Are parameters that need to be determined by calibration. Omega x 、ω y 、ω z Angular rates in three directions for gyroscopic sensitive projectiles, and what is needed in flight control in real time is ω X 、ω Y 、ω Z Obtained by calculation of the above equation.
Is a conversion matrix from the gyro instrument system Oxyz to the elastic body system OXYZ. As shown in fig. 1, coordinate systems Oxyz (instrument coordinate system) and xyz (projectile coordinate system) are shown.
Three accelerations a X 、a Y 、a Z ：
Wherein
Are parameters that need to be determined by calibration. a is x 、a y 、a z Acceleration in three directions of the projectile sensed by accelerometers, while flight control requires a in real time X 、a Y 、a Z Obtained by calculation of the above equation.
Is a conversion matrix of an accelerometer instrument system Oxyz to a projectile system OXYZ. As shown in fig. 1.
The conversion matrix, the scale factor and the zero offset in the calculation formula for obtaining the three angular rates and the three acceleration information required by the inertial measurement unit need to be obtained by calibrating the inertial measurement unit, and the calibration process needs to be based on a gyro error model and an accelerometer error model.
The gyro error model is written in the form of a matrix equation as follows:
wherein G is x 、G y 、G z Outputting values (the accumulated sum or the average value of the angular rates output in each period T) of the gyros respectively arranged along the x axis, the y axis and the z axis of the instrument system within T time; setting omega X 、ω Y 、ω Z For the excitation input under the projectile system at actual calibration, T is the set sampleTime. Matrix E in (1.1) and (2.1) g Are in inverse relationship with each other and are also in transposed relationship.
The accelerometer error model is written in the form of a matrix equation as follows:
wherein A is x 、A y 、A z Outputting values (the accumulated sum or the average value of the acceleration values output in each sampling period T) within T time by accelerometers respectively arranged along an x axis, a y axis and a z axis of the instrument system; setting a X 、a Y 、a Z T is the set sampling time for the excitation input under the projectile system in actual calibration. Matrix E in (1.2) and (2.2) a Are in inverse relationship with each other and are also in transposed relationship.
After parameters required for converting an instrument system and an elastic system are defined, the method comprises the following steps: converting the matrix (9 parameters forming the matrix are also called coupling error coefficients), the scale factor and the zero offset of each table, and the relationship between the scale factor and the zero offset and the error model of the gyroscope and the accelerometer.
During calibration, in the embodiment provided by the present disclosure, the inertia measurement unit is fixed in a regular hexahedron tool, the regular hexahedron tool is placed on a platform, such as a marble platform, and a normal vector of the platform coincides with a direction of a natural angular velocity component of the earth, as shown in fig. 2, the method includes the steps of:
and step S110, acquiring the gyro angular rate in each axial direction obtained when the inertia measurement unit rotates along three orthogonal axial directions of the regular hexahedron tool.
Exemplarily, in order to calibrate the gyro scale factor and the coupling error coefficient between different coordinate systems in the IMU, a certain angular rate excitation (ω in equation 2.1) needs to be input to the IMU X 、ω Y 、ω Z ) The angular rate may be dynamic and the gyro output in the corresponding axis (x, y, z) of the meter system is measured. Specifically, in this embodiment, taking the platform as a marble platform and the gyroscope as a Micro-Electro-Mechanical System (MEMS) gyroscope as an example, the generation of the input dynamic angular rate is obtained by using a method of rotating a regular hexahedron based on a calibration method of the marble platform.
Before calibration, the IMU is fixed on the regular hexahedron, the part of the regular hexahedron where the IMU is installed is provided with reference surfaces, generally only two reference surfaces are needed, and the IMU shell is provided with two corresponding reference surfaces, generally on the bottom surface and the side surface. The IMU housing and the square hexahedral tooling thus secured together form the elastic system xyz. And then placing the regular hexahedron on a marble platform, wherein a bearing reference surface is arranged on the platform and is vertical to the platform, so that the direction of the IMU calibrated axis is superposed with the direction of the natural angular velocity component of the earth, and the reference surface of the regular hexahedron is abutted against the reference surface on the platform. When the three calibrated axes X, Y, Z are calibrated, the positions of the three coordinate axes X, Y, Z and the output condition of the instrument are shown in fig. 3, 4 and 5. It should be noted that there are many places on the reference surface of the regular hexahedron, and the functions are different. Specifically, six faces such as a regular hexahedron can be used as reference faces for bearing the reference faces against the platform, or the platform surface; the part of the regular hexahedron where the IMU is installed is also provided with a reference surface for reference for installing the IMU. And will not be described in detail herein.
Rotating along three orthogonal axial directions of the regular hexahedron tool comprises rotating along the anticlockwise direction and rotating along the clockwise direction.
Taking calibration of the X-axis as an example, the main calibration steps are as follows:
and (3) counterclockwise rotation: and placing the regular hexahedron on the platform, and enabling the X axis to face upwards, namely enabling the X axis of the regular hexahedron tool to coincide with the direction of the natural angular velocity component of the earth. When the inertia measurement unit rotates along the X axis of the regular hexahedron tool, responding to timing operation, rotating the regular hexahedron around the X axis anticlockwise and uniformly by N.360 degrees within sampling time T, acquiring the angular rate of the gyroscope in each axial direction obtained when the inertia measurement unit rotates along the X axis of the regular hexahedron tool, and storing the output of the accumulated sum of the angular rates of the three gyroscopes
The regular hexahedron can not leave the horizontal plane of the marble in the rotating process, and the regular hexahedron is close to the reference surface of the platform after the rotation is finished.
Clockwise rotation: when the inertia measurement unit rotates along the X axis of the regular hexahedron tool, responding to timing operation, rotating the regular hexahedron around the X axis uniformly in a clockwise mode by N.360 degrees within sampling time T, acquiring the angular rate of each gyroscope in the axial direction obtained when the inertia measurement unit rotates along the X axis of the regular hexahedron tool, and storing the output of the accumulated sum of the angular rates of the three gyroscopes
The regular hexahedron can not leave the horizontal plane of the marble in the rotating process, and the regular hexahedron is close to the reference surface of the platform after the rotation is finished.
Similarly, the Y axis and the Z axis are calibrated to respectively obtain the test data of the Y, Z axis gyro, which are respectively
As an optional implementation manner, an angle rate average value may be obtained based on the angular rate accumulation sum, and the angle rate average value is taken as the gyro angular rate in the corresponding axial direction, which is not described herein again.
In the above N · 360 °, N represents the number of turns, and is a positive integer, for example, N =4, and the sampling time T may be adaptively set according to actual needs, for example, 100 seconds.
And step S120, calculating coupling error coefficients and scale factors of the gyroscope in each axial direction based on the angular rate of the gyroscope and environmental parameters, wherein the environmental parameters comprise the rotation angular rate of the earth and the geographical latitude under the current calibration environment.
Illustratively, by ω e To represent the angular rate of rotation of the earth, omega e =15.0411 degrees/hour; by using
To represent the geographic latitude in the current calibration environment. It should be noted that the rotational angular velocity ω of the earth e The horizontal component of =15.0411 degrees/hour is averaged out during N · 360 ° rotation of the regular hexahedron about a certain axis. Namely:
Wherein Ω is the input angular rate (obtained by rotating a regular hexahedron); alpha is an included angle between a bearing reference surface on the platform and a target geographic position, in the embodiment, an included angle between a marble bearing reference surface and a geographic north direction;
the angular rate of the gyro output is obtained by calibrating the gyro angular rate in step S110. When the X-axis of the missile system is forward upward and the regular hexahedron tooling rotates anticlockwise (positively) and clockwise (negatively) around the X-axis, the following equation is provided:
from the formula (3.1):
finishing to obtain:
when bullet system Y axle forward upwards, regular hexahedron frock is done anticlockwise (positive) rotation and clockwise (negative) rotation respectively around the Y axle, has the following equality:
from the formula (3.3):
finishing to obtain:
when the Z axis of the missile system is forward upward and the regular hexahedron tool respectively rotates anticlockwise (positively) and clockwise (negatively) around the Z axis, the following equations exist:
from the formula (3.5):
finishing to obtain:
due to the following:
The square sum of (3.2), (3.4) and (3.6) is finished to obtain:
from (3.2), (3.4) and (3.6):
the same treatment as the above process is carried out by (3.1), (3.3) and (3.5), and the following steps are carried out:
obtaining:
further comprising:
the same principle is as follows:
obtaining:
further comprising:
and obtaining a first conversion matrix according to the coupling error coefficients of the gyros in all the axial directions, wherein the first conversion matrix is used for realizing the conversion from the gyro instrument system to the elastic body system.
And step S130, acquiring position measurement values output by the gyroscope in each axial direction and position measurement values output by the accelerometers in each axial direction, which correspond to the inertial measurement unit on the preset transposition position of the regular hexahedron tool.
Illustratively, indexing refers to the different positions formed by turning the regular hexahedron so that the axes in the ammunition system are placed on the platform in different orientations when the position calibration is performed. The preset transposition refers to a preset position formed by turning the regular hexahedron. The position measurement value is obtained by placing the regular hexahedron on a platform and standing, and then obtaining the output values of the gyroscope and the accelerometer in each axial direction.
The speed calibration of the gyro is completed according to the steps S110 to S120, and the gyro is extracted
Scale factor sum->
Coupling error coefficients. />
Then, position calibration is carried out on the gyro and the accelerometer on the basis, and the zero-order term D of the gyro is extracted gyro 0x 、D gyro 0y 、D gyro 0z And zero order term of accelerometer
Scale factor>
And a coupling error coefficient.
For position calibration, there are many calibration options, including but not limited to, six-position method, eight-position method, etc. In the present embodiment, the preset indexing position takes a six-position method as an example, and the six positions are:
(1) south, west, (2) south, east, earth and north (3) east, east and north
(4) North, west and south (5, 6)
It is emphasized that the X, Y, Z axis is required to coincide with the corresponding position direction. Such as: "south-west" means that the X-axis points forward to "south", the Y-axis points forward to "day", and the Z-axis points forward to "west".
Zero calibration is carried out on the gyroscope:
the gyroscope needs to use environmental parameters for zero calibration, and comprises an included angle alpha between a bearing reference surface on a platform and a target geographic position, the local latitude is phi, and the rotational angular velocity omega of the earth at the moment e The components in each axial direction of the instrument system are:
where e represents a component in the x-axis direction in the instrument cluster, n represents a component in the y-axis direction in the instrument cluster, and t represents a component in the z-axis direction in the instrument cluster.
Corresponding to the preset six positions, there is a relative instrument at each positionPosition measurement of x-axis gyro measurement output under a system of meters
(i =1 south-west, 2 southeast, 3 northeast, 4 northeast, 5 northwest, 6 southwest).
The same principle is that:
corresponding to the preset six positions, there is a position measured value about the y-axis gyro measurement output under the instrument system at each position
(i =1 south-west, 2 south-east, 3 north-east, 4 north-east, 5 north-west, 6 west-south);
corresponding to the preset six positions, there is a position measured value about the z-axis gyro measuring output under the instrument system at each position
(i =1 south-west, 2 southeast, 3 northeast, 4 northeast, 5 northwest, 6 southwest).
In the process of calibrating the zero position of the gyroscope at the six positions, the position measurement value related to the accelerometer is also determined:
position measurement value output by x-axis accelerometer
position measurement value output by y-axis accelerometer
position measurement value output by z-axis accelerometer
And step S140, calculating the zero offset of the gyroscope in each axial direction based on the position measurement value output by the gyroscope, the coupling error coefficient and the scale factor.
Corresponding to the six positions of the turnover, an equation about the measurement output of the x-axis gyroscope under the instrument system is arranged at each position, 6 equations are obtained in total, and the equations are written into a matrix equation in the form of formula 4.1:
Summing the two ends of the 6 equations in (4.1) respectively to obtain:
corresponding to the flipped six positions, there is one equation for the y-axis gyro measurement output under the instrumentation train at each position, resulting in 6 equations, which are written in the form of matrix equations as follows.
summing the two ends of the 6 equations in (4.3) respectively to obtain:
corresponding to the flipped six positions, there is one equation for the z-axis gyro measurement output under the instrumentation train at each position, resulting in 6 equations, which are written in the form of matrix equations as follows.
summing up the two ends of the 6 equations in (4.5) respectively, we get:
and step S150, calculating the coupling error coefficient, the scale factor and the zero offset of the accelerometers in each axial direction based on the position measurement values output by the accelerometers.
In the process of calibrating the gyro zero position at six positions, all parameters related to the accelerometer are also determined.
In the six positions, the x-accelerometer measurement output is:
From (4.7) can be obtained:
because:
then:
further, the following are obtained:
the two ends of the 6 equations in (4.7) are added to obtain:
in the six positions, the y accelerometer measurement output is:
because:
then there are:
further obtaining:
the two ends of the 6 equations in (4.8) are added to obtain:
in the six positions, the z-accelerometer measurement output is:
because:
then there are:
further obtaining:
and obtaining a second conversion matrix according to the coupling error coefficients of the accelerometers in all the axial directions, wherein the second conversion matrix is used for realizing the conversion from the accelerometer system to the elastic system.
The two ends of the 6 equations in (4.9) are added to obtain:
therefore, under the test condition of the existing laboratory, instrument error compensation parameters required by the IMU can be obtained through reasonably planning the test process based on the regular hexahedron and the platform. The calibration parameter formula obtained by the method is as follows:
1) The parameters related to the three gyros are
The specific calculation is as follows: />
2) The parameters associated with the three accelerometers are
The calculation formula is as follows:
according to the inertial measurement unit calibration method provided by the embodiment of the invention, an expensive high-precision three-axis turntable or other rate turntables are not needed, a regular hexahedron with the advantages of simple design, small volume, low cost, simplicity in installation, simplicity in operation and the like is used as a mounting base of the inertial measurement unit, the calibration method of the gyroscope and the accelerometer can be completed by means of a marble platform, the method is irrelevant to a rotation speed error, the influence of the rotation speed error on a calibration result is avoided, a certain angular rate excitation is given to an IMU, and various indexes of the gyroscope can be calculated according to an output error model of the gyroscope. Meanwhile, the calibration method has strong universality and high calibration success rate on the premise of meeting the calibration precision, can realize quick calibration of the IMU, and has lower dependence on experience and capability of operators.
Fig. 6 is a device for calibrating an inertial measurement unit according to an embodiment of the present invention, where the inertial measurement unit includes a gyroscope and an accelerometer, the inertial measurement unit is fixed in a regular hexahedron fixture, the regular hexahedron fixture is placed on a platform, and a normal vector of the platform coincides with an earth rotation angular rate sky-direction component direction, and the device includes:
the first obtaining module 210 is configured to obtain a gyro angular rate in each axial direction obtained when the inertia measurement unit rotates along three orthogonal axial directions of the regular hexahedron tool. For details, refer to the description of the corresponding steps in the above embodiments, and are not repeated herein.
And the first calculation module 220 is configured to calculate a coupling error coefficient and a scaling factor of the gyroscope in each axis based on the gyroscope angular rate and environmental parameters, where the environmental parameters include the earth rotation angular rate and the geographic latitude in the current calibration environment. For details, refer to the description of the corresponding steps in the above embodiments, and are not repeated herein.
The second obtaining module 230 is configured to obtain position measurement values output by the inertial measurement unit on the preset transposition of the regular hexahedron tool in each axial direction from the gyroscope and position measurement values output by the accelerometers in each axial direction. For details, refer to the description of the corresponding steps in the above embodiments, and are not repeated herein.
And the second calculation module 240 is used for calculating the zero offset of the gyroscope in each axial direction based on the position measurement value output by the gyroscope, the coupling error coefficient and the scale factor. For details, refer to the description of the corresponding steps in the above embodiments, which are not repeated herein.
A third calculation module 250 for calculating the coupling error coefficient, the scaling factor and the null offset of each of the accelerometers in the axial direction based on the position measurements output by the accelerometers. For details, refer to the description of the corresponding steps in the above embodiments, which are not repeated herein.
As an optional implementation apparatus of the present invention, the apparatus further includes:
the first construction module is used for obtaining a first conversion matrix according to the coupling error coefficients of the gyros in all the axial directions, and the first conversion matrix is used for converting the instrument system into the elastic body system. For details, refer to the description of the corresponding steps in the above embodiments, which are not repeated herein.
And the second construction module is used for obtaining a second conversion matrix according to the coupling error coefficient of the accelerometer in each axial direction, and the second conversion matrix is used for converting the instrument system into the bomb system. For details, refer to the description of the corresponding steps in the above embodiments, which are not repeated herein.
As an optional implementation apparatus of the present invention, the first obtaining module 210 includes:
and the first timing submodule is used for responding to timing operation when the inertia measuring unit rotates along any orthogonal axis in three orthogonal axes of the regular hexahedron tool. For details, refer to the description of the corresponding steps in the above embodiments, and are not repeated herein.
The first obtaining submodule is used for obtaining angular rate accumulation in the corresponding axial direction when the corresponding axial direction of the regular hexahedron tool rotates within preset time. For details, refer to the description of the corresponding steps in the above embodiments, which are not repeated herein.
And the first calculation submodule is used for obtaining an angle rate average value based on the angular rate accumulation sum and taking the angle rate average value as the gyro angular rate in the corresponding axial direction. For details, refer to the description of the corresponding steps in the above embodiments, which are not repeated herein.
As an optional implementation apparatus of the present invention, the first obtaining module 210 includes:
and the second acquisition submodule is used for acquiring the angular rate of the gyroscope in each axial direction, which is obtained when the inertia measurement unit rotates along the axial direction of the regular hexahedron tool X, wherein the direction of the X axis of the regular hexahedron tool is superposed with the direction of the natural angular rate component of the earth. For details, refer to the description of the corresponding steps in the above embodiments, which are not repeated herein.
And the third acquisition submodule is used for acquiring the angular rate of the gyroscope in each axial direction, which is obtained when the inertia measurement unit rotates along the Y axial direction of the regular hexahedron tool, wherein the Y axis of the regular hexahedron tool is superposed with the direction of the natural component of the rotation angular rate of the earth. For details, refer to the description of the corresponding steps in the above embodiments, which are not repeated herein.
And the fourth acquisition submodule is used for acquiring the angular rate of the gyroscope in each axial direction, which is obtained when the inertia measurement unit rotates along the Z axial direction of the regular hexahedron tool, wherein the Z axial direction of the regular hexahedron tool is superposed with the direction of the natural angular rate component of the earth. For details, refer to the description of the corresponding steps in the above embodiments, and are not repeated herein.
As an optional implementation device of the invention, the device comprises: rotate including along anticlockwise rotation and along clockwise rotation along the three quadrature axial of regular hexahedron frock. For details, refer to the description of the corresponding steps in the above embodiments, and are not repeated herein.
As an optional implementation device of the invention, the platform is provided with a bearing reference surface which is vertical to the platform, and the environmental parameters further comprise an included angle between the bearing reference surface and the target geographic position; a second calculation module 240 comprising:
and the second calculation submodule is used for calculating the zero offset of the gyroscope in each axial direction based on the position measurement value output by the gyroscope, the coupling error coefficient, the scale factor and the included angle between the bearing reference surface and the target geographic orientation. For details, refer to the description of the corresponding steps in the above embodiments, and are not repeated herein.
As an optional implementation device of the invention, the device comprises: the gyroscope is a micro-electro-mechanical system gyroscope.
An embodiment of the present invention provides a computer apparatus, as shown in fig. 7, the apparatus includes one or more processors 810 and a storage 820, the storage 820 includes a persistent memory, a volatile memory, and a hard disk, and one processor 810 is taken as an example in fig. 7. The apparatus may further include: an input device 830 and an output device 840.
The processor 810, memory 820, input device 830, and output device 840 may be connected by a bus or other means, such as by bus in fig. 7.
An embodiment of the present invention provides a computer-readable storage medium, where the computer-readable storage medium stores computer instructions, and the computer-readable storage medium stores computer-executable instructions, where the computer-executable instructions may execute the method for calibrating an inertial measurement unit in any of the above method embodiments. The storage medium may be a magnetic Disk, an optical Disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a Flash Memory (Flash Memory), a Hard Disk (Hard Disk Drive, abbreviated as HDD), a Solid State Drive (SSD), or the like; the storage medium may also comprise a combination of memories of the kind described above.
The logic and/or steps represented in the flowcharts or otherwise described herein, such as an ordered listing of executable instructions that can be considered to implement logical functions, can be embodied in any computer-readable storage medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. For the purposes of this description, a "computer-readable storage medium" can be any means that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of the computer readable storage medium would include the following: an electrical connection (electronic device) having one or more wires, a portable computer cartridge (magnetic device), a Random Access Memory (RAM), a Read-Only Memory (ROM), an Erasable Programmable Read-Only Memory (EPROM or flash Memory), an optical fiber device, and a portable Compact Disc Read-Only Memory (CDROM). Additionally, the computer-readable storage medium may even be paper or another suitable medium upon which the program is printed, as the program can be electronically captured, via for instance optical scanning of the paper or other medium, then compiled, interpreted or otherwise processed in a suitable manner if necessary, and then stored in a computer memory.
It should be understood that portions of the present disclosure may be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, various steps or methods may be implemented in software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, any one or combination of the following techniques, which are known in the art, may be used: discrete logic circuits having logic Gate circuits for implementing logic functions on data signals, application specific integrated circuits having appropriate combinational logic Gate circuits, programmable Gate Arrays (PGAs), field Programmable Gate Arrays (FPGAs), and the like.
In the description herein, reference to the description of the terms "this embodiment," "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present disclosure. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction. In the description of the present disclosure, "a plurality" means at least two, e.g., two, three, etc., unless explicitly specifically limited otherwise.
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications of the invention may be made without departing from the spirit or scope of the invention.
Claims (10)
1. An inertial measurement unit calibration method comprises a gyroscope and an accelerometer, wherein the inertial measurement unit is fixed in a regular hexahedron tool, the regular hexahedron tool is arranged on a platform, and a normal vector of the platform is superposed with the direction of the natural angular velocity component of the earth; characterized in that the method comprises:
acquiring gyro angular rates in all axial directions, which are obtained when an inertia measurement unit rotates along three orthogonal axial directions of a regular hexahedron tool;
calculating coupling error coefficients and scale factors of the gyros in all the axial directions based on the angular rates of the gyros and environmental parameters, wherein the environmental parameters comprise the rotation angular rates of the earth and the geographic latitudes under the current calibration environment;
obtaining position measurement values output by gyros in all axial directions and position measurement values output by accelerometers in all axial directions, which correspond to the inertia measurement unit on the preset transposition of the regular hexahedron tool;
calculating the zero offset of the gyroscope in each axial direction based on the position measurement value output by the gyroscope, the coupling error coefficient and the scale factor;
coupling error coefficients, scaling factors and zero offset of the accelerometers in each axis are calculated based on position measurements output by the accelerometers.
2. The inertial measurement unit calibration method of claim 1, further comprising:
obtaining a first conversion matrix according to coupling error coefficients of the gyros in all axial directions, wherein the first conversion matrix is used for converting an instrument system into a projectile system;
and obtaining a second conversion matrix according to the coupling error coefficient of the accelerometer in each axial direction, wherein the second conversion matrix is used for converting the instrument system into the bomb system.
3. The method for calibrating the inertial measurement unit according to claim 1, wherein the obtaining of the gyro angular rate in each axial direction obtained when the inertial measurement unit rotates along three orthogonal axial directions of the regular hexahedron tool comprises:
when the inertia measuring unit rotates along any orthogonal axis of the three orthogonal axes of the regular hexahedron tool, timing operation is responded;
acquiring the angular rate accumulated sum in the corresponding axial direction when the regular hexahedron tool rotates along the corresponding axial direction within a preset time;
and obtaining an angle rate average value based on the angular rate accumulation sum, and taking the angle rate average value as the gyro angular rate in the corresponding axial direction.
4. The method for calibrating the inertial measurement unit according to claim 1, wherein the obtaining of the gyro angular rate in each axial direction obtained when the inertial measurement unit rotates along three orthogonal axial directions of the regular hexahedron tool comprises:
obtaining the angular rate of the gyroscope in each axial direction obtained when the inertia measurement unit rotates along the axial direction of a regular hexahedron tool X, wherein the X axis of the regular hexahedron tool is superposed with the direction of the natural component of the angular rate of the earth rotation;
obtaining the angular rate of the gyroscope in each axial direction obtained when the inertia measurement unit rotates along the Y axial direction of the regular hexahedron tool, wherein the Y axis of the regular hexahedron tool is superposed with the direction of the natural component of the earth rotation angular rate;
and obtaining the angular rate of the gyroscope in each axial direction obtained when the inertia measurement unit rotates along the Z axial direction of the regular hexahedron tool, wherein the Z axial direction of the regular hexahedron tool is superposed with the direction of the natural component of the angular rate of the earth rotation.
5. The inertial measurement unit calibration method of claim 1, wherein the rotation along three orthogonal axes of the regular hexahedron tooling comprises counterclockwise rotation and clockwise rotation.
6. The inertial measurement unit calibration method according to claim 1, wherein a bearing reference plane is arranged on the platform, the bearing reference plane is perpendicular to the platform, and the environmental parameters further include an included angle between the bearing reference plane and a target geographic position; the calculating of the zero offset of the gyroscope in each axial direction based on the position measurement value output by the gyroscope, the coupling error coefficient and the scale factor comprises:
and calculating the zero offset of the gyroscope in each axial direction based on the position measurement value output by the gyroscope, the coupling error coefficient, the scale factor and the included angle between the bearing reference surface and the target geographic orientation.
7. The inertial measurement unit calibration method of claim 1, wherein the gyroscope is a micro-electromechanical system gyroscope.
8. An inertial measurement unit calibration device comprises a gyroscope and an accelerometer, wherein the inertial measurement unit is fixed in a regular hexahedron tool, the regular hexahedron tool is arranged on a platform, and a normal vector of the platform is superposed with the direction of the natural angular velocity component of the earth; it is characterized by comprising the following steps:
the first acquisition module is used for acquiring gyro angular rates in all axial directions obtained when the inertia measurement unit rotates along three orthogonal axial directions of the regular hexahedron tool;
the first calculation module is used for calculating a coupling error coefficient and a scale factor of the gyroscope in each axial direction based on the angular rate of the gyroscope and environmental parameters, wherein the environmental parameters comprise the rotation angular rate of the earth and the geographic latitude under the current calibration environment;
the second acquisition module is used for acquiring position measurement values output by the gyroscope in each axial direction and position measurement values output by the accelerometers in each axial direction, which correspond to the inertial measurement unit on the preset transposition of the regular hexahedral tool;
the second calculation module is used for calculating the zero offset of the gyroscope in each axial direction based on the position measurement value output by the gyroscope, the coupling error coefficient and the scale factor;
and the third calculation module is used for calculating the coupling error coefficient, the scaling factor and the zero offset of the accelerometers in each axial direction based on the position measurement values output by the accelerometers.
9. The computer equipment is characterized by comprising a processor, a communication interface, a memory and a communication bus, wherein the processor and the communication interface are used for realizing the communication between the processor and the memory through the communication bus;
a memory for storing a computer program;
a processor for implementing the steps of the inertial measurement unit calibration method of any one of claims 1-7 when executing the program stored on the memory.
10. A computer-readable storage medium, on which a computer program is stored which, when being executed by a processor, carries out the steps of the inertial measurement unit calibration method of any one of claims 1-7.
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| CN116990045A (en) * | 2023-05-18 | 2023-11-03 | 运来智能装备(无锡)有限公司 | Drive-by-wire chassis scale factor calibration method, system and medium based on inertial measurement |
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| CN116990045A (en) * | 2023-05-18 | 2023-11-03 | 运来智能装备(无锡)有限公司 | Drive-by-wire chassis scale factor calibration method, system and medium based on inertial measurement |
| CN116990045B (en) * | 2023-05-18 | 2024-04-05 | 运来智能装备(无锡)有限公司 | Drive-by-wire chassis scale factor calibration method, system and medium based on inertial measurement |
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