CN110595504A - Automatic calibration method and automatic calibration system for inertial measurement unit - Google Patents
Automatic calibration method and automatic calibration system for inertial measurement unit Download PDFInfo
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- CN110595504A CN110595504A CN201910847848.0A CN201910847848A CN110595504A CN 110595504 A CN110595504 A CN 110595504A CN 201910847848 A CN201910847848 A CN 201910847848A CN 110595504 A CN110595504 A CN 110595504A
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- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
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Abstract
The invention discloses an automatic calibration method and an automatic calibration system of an inertia measurement unit, wherein the inertia measurement unit to be tested and a processor form an inertia system to be calibrated, the inertia system to be calibrated is arranged on a turntable, and a calibration program is burnt in the processor in advance, the automatic calibration method comprises the following steps: sequentially adjusting the working state of the rotary table; when the rotary table runs at a preset calibration point, the processor sequentially acquires test data of the inertia measurement unit based on a calibration program until all test data corresponding to the preset calibration point are obtained; the processor fits preset calibration points with the test data based on the calibration program to obtain calibration parameters, and the calibration parameters are stored in a memory of the inertial system to be calibrated. According to the automatic calibration method, the acquisition and storage of the test data and the execution of the calibration algorithm are automatically executed in the processor on the side of the inertial system to be calibrated, so that the process of interactive communication between the inertial measurement system and external equipment in the prior art is avoided.
Description
Technical Field
The invention belongs to the field of sensors, and particularly relates to an automatic calibration method and an automatic calibration system of an inertia measurement unit.
Background
With the rapid development of MEMS (micro electro Mechanical Systems, abbreviated as MEMS) technology, a great number of sensors based on MEMS technology are also available, wherein an Inertial measurement unit IMU (Inertial measurement unit, abbreviated as IMU) is a rather typical MEMS sensor. However, due to the process limitation of the MEMS technology and the variability in actual production, the MEMS IMU sensor products produced by manufacturers have certain errors, for example, the orthogonality of the three reference axes of the IMU is poor, the cross-coupling error occurs in measurement, and the production variability of each IMU sensor occurs. Therefore, when the MEMS IMU sensor is actually used, particularly when relatively high-precision measurement is required, the MEMS IMU sensor needs to be calibrated one by one.
In view of the above, overcoming the drawbacks of the prior art is an urgent problem in the art.
Disclosure of Invention
Aiming at the defects or the improvement requirements of the prior art, the invention provides an automatic calibration method and an automatic calibration system of an inertial measurement unit, aiming at calibrating an IMU by the automatic calibration method to eliminate the error of the IMU, thereby solving the technical problem of error of an IMU sensor.
In order to achieve the above object, according to one aspect of the present invention, there is provided an automatic calibration method for an inertial measurement unit, in which an inertial measurement unit to be tested and a processor form an inertial system to be calibrated, the inertial system to be calibrated is disposed on a turntable, and a calibration program is pre-programmed into the processor, the automatic calibration method including:
sequentially adjusting the working state of the rotary table to enable the rotary table to operate at a preset calibration point;
when the rotary table runs at a preset calibration point, the processor sequentially acquires the test data of the inertia measurement unit based on the calibration program until all the test data corresponding to the preset calibration point are obtained;
and the processor fits the preset calibration points with the test data based on the calibration program to obtain calibration parameters, and stores the calibration parameters into a memory of the inertial system to be calibrated so as to compensate the inertial measurement unit according to the calibration parameters.
Preferably, the preset calibration point includes a preset rotation speed, and when the turntable runs at the preset calibration point, the processor sequentially obtains the test data of the inertial measurement unit based on the calibration program until all the test data corresponding to the preset calibration point are obtained includes:
acquiring the rotation speed of the rotary table through the inertia measurement unit;
when the rotating speed of the rotary table exceeds a set speed threshold value, the processor starts to store the test data of the gyroscope of the inertia measurement unit until the rotating speed of the rotary table is equal to the preset rotating speed, so as to obtain a plurality of test data corresponding to the same preset rotating speed;
and screening the plurality of test data corresponding to the same preset rotating speed to obtain the measurement data matched with the preset rotating speed.
Preferably, the preset calibration point includes a preset axial position, the preset axial position is in the same direction as the direction of the gravitational acceleration, and when the turntable operates at the preset calibration point, the processor sequentially obtains the test data of the inertial measurement unit based on the calibration program until all the test data corresponding to the preset calibration point are obtained includes:
acquiring the gravity acceleration corresponding to the target shaft of the rotary table through the inertia measurement unit in the process of rotating the target shaft of the rotary table at a preset axial position;
when the gravity acceleration corresponding to the target shaft of the rotary table exceeds a set gravity acceleration threshold value, the processor starts to store the test data of the accelerometer of the inertia measurement unit until the target shaft of the rotary table rotates to a preset axial position, so as to obtain a plurality of test data corresponding to the same preset axial position;
and screening the plurality of test data corresponding to the same preset axial position to obtain the measurement data matched with the preset axial position.
Preferably, the number of the target axes of the turntable is multiple, and the rotation of the preset axial position of each target axis is sequentially adjusted to respectively obtain the measurement data of the accelerometer of the inertia measurement unit in the positive direction of the X axis, the negative direction of the X axis, the positive direction of the Y axis, the negative direction of the Y axis, the positive direction of the Z axis and the negative direction of the Z axis.
Preferably, the fitting the preset calibration point with the test data by the processor based on the calibration program to obtain a calibration parameter, and storing the calibration parameter in a memory of the inertial system to be calibrated, so as to compensate the inertial measurement unit according to the calibration parameter includes:
the processor calculates the reference data corresponding to the preset calibration point and the test data by a least square method based on the calibration program to obtain a scale factor and an offset;
and storing the scale factor and the offset into a memory of the inertial system to be measured so as to compensate the inertial measurement unit.
Preferably, the automatic calibration method further includes:
after the calibration parameters are obtained, the rotary table is adjusted again to operate under the preset calibration point in sequence;
the processor compensates the data collected by the inertia measurement unit according to the calibration parameters to obtain compensated compensation data;
comparing the compensation data with reference data corresponding to the preset calibration point;
and when the difference between the compensation data and the reference data corresponding to the preset calibration point is smaller than a specified threshold value, taking the calibration parameter as a target calibration parameter.
Preferably, when the difference between the compensation data and the reference data corresponding to the preset calibration point is not less than a specified threshold, the inertial measurement unit is calibrated again until the difference between the compensation data and the reference data corresponding to the preset calibration point is less than the specified threshold.
Preferably, when the difference between the compensation data and the reference data corresponding to the preset calibration point is not less than a specified threshold, the inertial measurement unit is calibrated again within a set calibration number, and if the inertial measurement unit cannot meet a retest condition all the time, the inertial measurement unit is marked as a suspected faulty product to perform fault determination.
Preferably, the calibration program pre-programmed in the processor includes calibration points matched with the inertial measurement unit to be measured.
According to another aspect of the present invention, there is provided an automatic calibration system of an inertial measurement unit, the automatic calibration system comprising: the system comprises a rotary table and a control cabinet, wherein the control cabinet is connected with the rotary table, an inertia measuring unit to be tested and a processor form an inertia system to be calibrated, the inertia system to be calibrated is arranged on the rotary table, and a calibration program is burnt in the processor in advance; the control cabinet, the rotary table and the inertial system to be calibrated are matched with each other to realize the automatic calibration method.
Generally, compared with the prior art, the technical scheme of the invention has the following beneficial effects: the invention provides an automatic calibration method and an automatic calibration system of an inertia measurement unit, wherein the inertia measurement unit to be tested and a processor form an inertia system to be calibrated, the inertia system to be calibrated is arranged on a rotary table, a calibration program is burnt in the processor in advance, and the automatic calibration method comprises the following steps: sequentially adjusting the working state of the rotary table to enable the rotary table to operate at a preset calibration point; when the rotary table runs at a preset calibration point, the processor sequentially acquires the test data of the inertia measurement unit based on the calibration program until all the test data corresponding to the preset calibration point are obtained; the processor fits preset calibration points with the test data based on the calibration program to obtain calibration parameters, and the inertial measurement unit is compensated according to the calibration parameters. According to the automatic calibration method, the acquisition and storage of the test data of the inertia measurement unit and the execution of the calibration algorithm are automatically executed in the processor on the side of the inertia system to be calibrated, so that the process of frequent interactive communication between the inertia measurement system and external equipment in the prior art is avoided, manual operation can be greatly reduced, the production efficiency of products is improved, and the error rate is reduced in batch production.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required to be used in the embodiments of the present invention will be briefly described below. It is obvious that the drawings described below are only some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort.
Fig. 1 is a schematic flow chart of an automatic calibration method for an inertial measurement unit according to an embodiment of the present invention;
FIG. 2 is a schematic flow chart illustrating another method for automatically calibrating an inertial measurement unit according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of an automatic calibration system of an inertial measurement unit according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
In practical use, the MEMS IMU is the core of an inertial navigation system and plays an important role in the fields of unmanned aerial vehicles, robots, automatic driving, virtual reality and the like. Through the data of the MEMS IMU, the attitude angle and the azimuth angle of the movement at any moment can be calculated. For improving the calculation accuracy, an important measure is to eliminate the error of the MEMS IMU, i.e. to calibrate it.
At present, for the calibration of MEMS IMU, a relatively common method is a fixed rate calibration method. Specifically, the MEMS IMU system is arranged on a three-axis turntable, the turntable is set to rotate at a fixed speed, and data of MEMS IMU sensors are collected through a signal line and stored on a computer. During calibration, data needs to be continuously acquired, the processed data volume is large, much data is data in the unstable speed regulation process of the rotary table, and the data is not needed during actual calibration. Because the data volume is bigger, just need to send the data of gathering out from the system end, save on computer memory temporarily, the work load is big and loaded down with trivial details, also can increase the equipment maintenance cost and mark the complete mistake of data because of reasons such as communication interruption, manual operation mistake in the processing process.
Example 1：
In order to solve the foregoing problems, this embodiment provides an automatic calibration method for an Inertial Measurement Unit (IMU), where an inertial measurement unit to be tested and a processor form an inertial system to be calibrated, the inertial system to be calibrated is disposed on a turntable, and a calibration program is pre-programmed in the processor, and referring to fig. 1, the automatic calibration method of this embodiment includes the following steps:
step 10: and sequentially adjusting the working state of the rotary table so that the rotary table runs at a preset calibration point.
The automatic calibration method of the embodiment is mainly applicable to an assembly or system including an IMU, wherein the assembly or system including the IMU has data processing capability, and in an actual test, the assembly or system including the IMU is arranged on a three-axis turntable or a six-axis turntable, and the state of the IMU is switched by the three-axis turntable or the six-axis turntable so as to acquire output data of the IMU.
Specifically, the inertia measurement unit and the processor form an inertia system to be calibrated, the inertia system to be calibrated is arranged on the turntable, a calibration program is burnt in the processor in advance, calibration is automatically completed through the calibration program in the processor, and the process that the inertia system is frequently communicated with an external computer in the prior art is avoided.
In an actual test, the turntable is generally required to move to a specific position or rotate at a constant speed, and then data acquisition is performed through the IMU. After the turntable starts to move, the position and/or the speed of the turntable can be acquired in real time, and the fed back position information and/or speed information is compared with the preset position and/or speed information to determine whether the turntable runs under the preset calibration point.
The automatic calibration method is realized by depending on a control cabinet, wherein the control cabinet is used for adjusting the working state of the rotary table and acquiring the feedback information of the rotary table in real time so as to determine whether the rotary table operates at a preset calibration point.
The measurement object aimed at by the embodiment is an inertial measurement system including an IMU, a calibration program includes a calibration point matched with an inertial measurement unit to be calibrated, and in the calibration process, a corresponding calibration point is set on the control cabinet, so that the turntable can operate at the calibration point. In the operation process of the rotary table, the processor controls the inertia measurement unit to collect data according to the calibration program so as to monitor the motion state of the rotary table, when the rotary table rotates to the position near the calibration point, the data are stored, and data fitting is carried out based on the test data of the IMU and the reference data corresponding to the calibration point, so that the calibration parameters of the IMU are obtained.
Step 11: and when the rotary table runs at a preset calibration point, the processor sequentially acquires the test data of the inertia measurement unit based on the calibration program until all the test data corresponding to the preset calibration point are obtained.
The method comprises the steps of acquiring test data of an inertia measurement unit for each preset calibration point, controlling a rotary table to run under a certain preset calibration point in an actual calibration process, acquiring the test data corresponding to the preset calibration point, then controlling the rotary table to run under another preset calibration point, acquiring the test data corresponding to the preset calibration point, and so on to obtain all the test data corresponding to the preset calibration point.
Step 12: and the processor fits the preset calibration points with the test data based on the calibration program to obtain calibration parameters, and stores the calibration parameters into a memory of the inertial system to be calibrated so as to compensate the inertial measurement unit according to the calibration parameters.
Since the IMU is disposed on the turntable, the motion state of the IMU is the same as that of the turntable. In this embodiment, the motion state of the turntable is reflected from two different dimensions, the first dimension being: reference data which is sent by a control cabinet of the rotary table and is matched with a preset calibration point; the second dimension is: test data monitored by the IMU. The reference data in the first dimension is accurate and can be matched with the motion state of the turntable, and the accuracy of the test data in the second dimension is uncertain and is determined by the error of the IMU. In view of this, the calibration parameters of the IMU may be calculated through the test data of the IMU and the reference data matched with the preset calibration point, so as to compensate the IMU through the calibration parameters and eliminate errors.
In an optional scheme, the processor performs least square calculation on the reference data corresponding to the preset calibration point and the test data based on the calibration program to obtain a scale factor and an offset; saving the scale factor and the offset to a memory of the inertial system to compensate an inertial measurement unit.
The scale factors include a gyroscope scale factor, an accelerometer scale factor and the like so as to compensate data corresponding to a gyroscope and an accelerometer of the IMU respectively.
In this embodiment, the collection and storage of the test data of the IMU are directly performed by the processor corresponding to the IMU, and intelligent devices such as an external computer are not required to participate, so that the communication process of the external device can be greatly reduced, the data delay is reduced, and the calibration efficiency is improved. Moreover, manual operation can be greatly reduced, the production efficiency of products is improved, and the error rate is reduced in batch production.
In an implementation application scenario, a gyroscope and an accelerometer are integrated in the IMU, wherein angular velocity information can be acquired through the gyroscope, and acceleration information can be acquired through the accelerometer.
In an implementation application scenario, in the process that the turntable starts to move to a preset calibration point, the inertial system is powered on, the inertial measurement unit starts to acquire data, and thus more invalid data are generated, because the internal memory of the inertial system is limited, in order to fully utilize the internal memory, a threshold point (a threshold value described below) is set for the data acquired by the inertial measurement unit, and only effective data reaching the threshold point is stored in the internal memory, and a specific implementation manner is as follows:
in one embodiment, the preset calibration point includes a preset rotation speed, and step 12 specifically includes: acquiring the rotation speed of the rotary table through the inertia measurement unit; when the rotating speed of the rotary table exceeds a set speed threshold value, the processor starts to store the test data of the gyroscope of the inertia measurement unit until the rotating speed of the rotary table is equal to the preset rotating speed, so as to obtain a plurality of test data corresponding to the same preset rotating speed; and screening the plurality of test data corresponding to the same preset rotating speed to obtain the measurement data matched with the preset rotating speed.
The step is mainly to obtain the test data of the gyroscope of the inertial measurement unit so as to perform error compensation on the gyroscope of the inertial measurement unit.
In another embodiment, the preset calibration point includes a preset axial position, the preset axial position is in the same direction as the direction of the gravitational acceleration, and the step 12 specifically includes: acquiring the gravity acceleration corresponding to the target shaft of the rotary table through the inertia measurement unit in the process of rotating the target shaft of the rotary table at a preset axial position; when the gravity acceleration corresponding to the target shaft of the rotary table exceeds a set gravity acceleration threshold value, the processor starts to store the test data of the accelerometer of the inertia measurement unit until the target shaft of the rotary table rotates to a preset axial position, so as to obtain a plurality of test data corresponding to the same preset axial position; and screening the plurality of test data corresponding to the same preset axial position to obtain the measurement data matched with the preset axial position.
The target axis of revolving stage is a plurality of, adjusts each target axis in proper order and locates the rotation in the preset axial position to obtain respectively inertial measurement unit's accelerometer's measuring data in X axle positive direction, X axle negative direction, Y axle positive direction, Y axle negative direction, Z axle positive direction and the Z axle negative direction.
The step is mainly to acquire test data of an accelerometer of the inertial measurement unit so as to perform error compensation on a gyroscope of the inertial measurement unit.
According to the method, a large amount of useless data can be prevented from being stored in the memory, and the utilization rate of the memory is effectively improved.
In a preferred embodiment, in order to avoid an error caused by calculation or data mis-acquisition, after the calibration parameter is obtained by calculation, the IMU is retested according to the calibration parameter, specifically, the automatic calibration method further includes: after the calibration parameters are obtained, the rotary table is adjusted again to operate under the preset calibration point in sequence; the processor compensates the data collected by the inertia measurement unit according to the calibration parameters to obtain compensated data after data compensation; comparing the compensation data with reference data corresponding to the preset calibration point; and when the difference between the compensation data and the reference data corresponding to the preset calibration point is smaller than a specified threshold value, taking the calibration parameter as a target calibration parameter. The specified threshold value can be determined according to actual conditions, and the smaller the specified threshold value is, the higher the calibration accuracy is.
In an optional scheme, when the difference between the compensation data and the reference data corresponding to the preset calibration point is not less than a specified threshold, the inertial measurement unit is calibrated again until the difference between the compensation data and the reference data corresponding to the preset calibration point is less than the specified threshold, so as to eliminate the influence of an actual calibration environment on a calibration result.
In another optional scheme, when a difference between the compensation data and reference data corresponding to the preset calibration point is not less than a specified threshold, the inertial measurement unit is calibrated again within a set calibration number, and if the inertial measurement unit cannot meet a retest condition all the time, the inertial measurement unit is marked as a suspected faulty product to perform fault determination. The preset calibration time may be 2 times, 3 times or other values, and is not limited herein. And the retest condition refers to that the difference between the compensation data and the reference data corresponding to the preset calibration point is smaller than a specified threshold value.
Different from the prior art, in the automatic calibration method of the invention, data acquisition, data storage and calibration data calculation are all completed in the MCU at the IMU side, so that the communication process (for example, the communication process of transmitting data to a computer, calculating calibration parameters on the computer and transmitting the calibration parameters back to the system) of acquiring a large amount of invalid data and the communication process of the IMU and an external terminal (in the prior art) can be avoided. The invention has simple operation and higher efficiency, can completely cancel the communication process of the original scheme, and reduces the necessary equipment addition and maintenance. Excessive data maintenance and possible data confusion errors can also be avoided when calibrating batch products. In addition, the calibration parameter can be quickly checked by adding an internal retest process.
In an actual application scenario, when calibrating different IMUs, corresponding calibration points are different, and in order to ensure that the calibration points are matched with the IMUs one by one, in a preferred embodiment, before step 10, the method further includes: the method comprises the steps of obtaining the specification and/or model of an inertial measurement unit to be calibrated, and determining a calibration point matched with the inertial measurement unit to be calibrated according to the specification and/or model of the inertial measurement unit to be calibrated.
In the actual calibration, the test data of the inertia measurement units of the same batch can be obtained, wherein the specifications or the models of the inertia measurement units of the same batch are the same, the test data of the inertia measurement units of the same batch are stored in the configuration table, the consistency of the test data of the inertia measurement units of the same batch is determined through data comparison, and when the test data of the inertia measurement units of the same batch is lower than a set threshold, the consistency of the inertia measurement units of the same batch is poor. In this case, the environmental information, the material information, the process information and the like of the inertia measurement units for manufacturing the batch are acquired, and the environmental information, the material information and the process information of the inertia measurement units for manufacturing the batch are rechecked to determine factors influencing the consistency, so that the problem of poor consistency is avoided, and the batch stability of the product is improved.
Example 2：
The following describes, with reference to fig. 2, an automatic calibration process of the IMU in an actual application scenario. When the IMU is calibrated, the method mainly comprises the following three stages:
(1) a preparation stage: and (4) downloading a functional program containing the MEMS IMU sensor system and a calibration method program into the MCU of the system, and then installing and fixing the IMU on the turntable. And an external circuit is arranged, so that the selection of the mode can be identified after the GPIO of the system MCU is electrified, and the calibration can be automatically carried out.
(2) A calibration stage: firstly, a system containing an IMU is powered on, and after the MCU identifies that a certain GPIO port is a specific level, the MCU runs a calibration program. In the calibration procedure, calibration points to be calibrated are preset, in the calibration process, the turntable is controlled to sequentially reach the preset calibration points, and test data of the MEMS IMU are collected. In the process, the calibration of the gyroscope and the calibration of the accelerometer are mainly divided.
In this embodiment, the calibration of the gyroscope is performed first, but in other embodiments, the calibration of the accelerometer may be performed first. Firstly, the turntable is started to rotate, and in the speed regulation process that the turntable does not reach the set rotating speed, the MCU can read the measurement data of the MEMS IMU, but cannot store the data of the MEMS IMU.
By setting a sampling threshold in a calibration program of the MCU, the MCU can save the read MEMS IMU data only when the turntable rotates to a position near a preset calibration point, and primarily process the data, and update the stable MEMS IMU data to a final memory as test data corresponding to the preset calibration point. After the data acquisition of all the preset calibration points is finished, the MCU prompts the completion of the data acquisition of the current calibration point so as to carry out the data acquisition of the calibration point corresponding to the accelerometer.
Then, MEMS IMU accelerometer data acquisition is performed. Similarly, a sampling threshold of the accelerometer is arranged in the MCU, the movement of the turntable is adjusted, a certain axial direction of the turntable is adjusted to the direction in the same direction as the gravity acceleration, and the MCU reads and stores actual output data of the MEMS IMU accelerometer. And after the data acquisition of all the preset calibration points is finished, the MCU prompts that the data acquisition of the current calibration point is finished. Data of the accelerometers +/-X, + -Y, + -Z and six directions are collected in sequence according to the mode.
After the acquisition of the calibration point data of the gyroscope and the acquisition of the calibration point data of the accelerometer are completed, a fitting algorithm is carried out according to the data corresponding to the preset calibration point and the acquired test data to obtain calibration parameters, and the scale factor and the offset are stored in a specific memory address of the MCU.
(3) And (3) retesting: and after the calibration parameters are calculated, retesting the calibration parameters to verify the calibration parameters. Specifically, the turntable is adjusted to rotate at a calibration speed in sequence and maintain a specific calibration axis direction, and at the moment, since calibration parameters (scale factors and offset) exist in a specific address of the MCU, a program can automatically use the parameters to compensate the original data of the MEMS IMU, compare the obtained compensation data with data corresponding to a calibration point, and when a set difference threshold value is met, the calibration parameters are accurate, so that the calibration of the IMU is completed.
The automatic calibration method provided by the invention has the following characteristics: simultaneously burning a functional program and a calibration program of the MEMS IMU system into an MCU of the system in advance; accessing a specific level by configuring GPIO of the MCU, so that the MCU runs a calibration program; by setting a sampling threshold value in a calibration program, the MCU can store sampling data only when the threshold value is met; the data fitting algorithm is used as a part of a calibration program, runs calculation in a system MCU, and stores calibration parameters; and completing self-checking of the calibration parameters by adding a retest process.
Different from the prior art, in the automatic calibration method of the invention, data acquisition, data storage and calibration data calculation are all completed in the MCU at the IMU side, so that the communication process (for example, the communication process of transmitting data to a computer, calculating calibration parameters on the computer and transmitting the calibration parameters back to the system) of acquiring a large amount of invalid data and the communication process of the IMU and an external terminal (in the prior art) can be avoided. The invention has simple operation and higher efficiency, can completely cancel the communication process of the original scheme, and reduces the necessary equipment addition and maintenance. Excessive data maintenance and possible data confusion errors can also be avoided when calibrating batch products. In addition, the calibration parameter can be quickly checked by adding an internal retest process.
Example 3：
Based on the automatic calibration method of the foregoing embodiment, this embodiment provides an automatic calibration system of an inertial measurement unit, and referring to fig. 3, the automatic calibration system includes: the system comprises a rotary table and a control cabinet, wherein the control cabinet is connected with the rotary table, an inertia measuring unit to be tested and a processor form an inertia system to be calibrated, the inertia system to be calibrated is arranged on the rotary table, and a calibration program is burnt in the processor in advance; the control cabinet, the rotary table and the inertial measurement system to be calibrated are matched with each other, and are used for realizing the automatic calibration method of any one of the embodiments.
Specifically, the control cabinet is configured to sequentially adjust a working state of the turntable, so that the turntable operates at a preset calibration point, where the preset calibration point is burned into the processor in advance, and may be determined based on an actual measurement requirement of the inertia measurement unit.
Sequentially acquiring the test data of the inertia measurement unit by a corresponding processor in the IMU system based on a pre-burnt calibration program until all the test data corresponding to the preset calibration point are obtained; and the processor fits the preset calibration points with the test data based on a calibration program to obtain calibration parameters, and stores the calibration parameters into a memory of the inertial system to be calibrated so as to compensate the inertial measurement unit according to the calibration parameters.
For details of the automatic calibration method, please refer to embodiment 1 and embodiment 2, which are not described herein again.
It should be noted that, for the information interaction, execution process and other contents between the modules and units in the apparatus and system, the specific contents may refer to the description in the embodiment of the method of the present invention because the same concept is used as the embodiment of the processing method of the present invention, and are not described herein again.
Those of ordinary skill in the art will appreciate that all or part of the steps of the various methods of the embodiments may be implemented by associated hardware as instructed by a program, which may be stored on a computer-readable storage medium, which may include: a Read Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and the like.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (10)
1. An automatic calibration method for an inertial measurement unit is characterized in that the inertial measurement unit to be tested and a processor form an inertial system to be calibrated, the inertial system to be calibrated is arranged on a rotary table, and a calibration program is burnt in the processor in advance, and the automatic calibration method comprises the following steps:
sequentially adjusting the working state of the rotary table to enable the rotary table to operate at a preset calibration point;
when the rotary table runs at a preset calibration point, the processor sequentially acquires the test data of the inertia measurement unit based on the calibration program until all the test data corresponding to the preset calibration point are obtained;
and the processor fits the preset calibration points with the test data based on the calibration program to obtain calibration parameters, and stores the calibration parameters into a memory of the inertial system to be calibrated so as to compensate the inertial measurement unit according to the calibration parameters.
2. The automatic calibration method according to claim 1, wherein the preset calibration point comprises a preset rotation speed, and when the turntable runs at the preset calibration point, the processor sequentially obtains the test data of the inertial measurement unit based on the calibration program until all the test data corresponding to the preset calibration point are obtained comprises:
acquiring the rotation speed of the rotary table through the inertia measurement unit;
when the rotating speed of the rotary table exceeds a set speed threshold value, the processor starts to store the test data of the gyroscope of the inertia measurement unit until the rotating speed of the rotary table is equal to the preset rotating speed, so as to obtain a plurality of test data corresponding to the same preset rotating speed;
and screening the plurality of test data corresponding to the same preset rotating speed to obtain the measurement data matched with the preset rotating speed.
3. The automatic calibration method according to claim 1, wherein the preset calibration point includes a preset axial position, the preset axial position is in the same direction as the direction of the gravitational acceleration, and when the turntable operates at the preset calibration point, the processor sequentially obtains the test data of the inertial measurement unit based on the calibration program until obtaining all the test data corresponding to the preset calibration point includes:
acquiring the gravity acceleration corresponding to the target shaft of the rotary table through the inertia measurement unit in the process of rotating the target shaft of the rotary table at a preset axial position;
when the gravity acceleration corresponding to the target shaft of the rotary table exceeds a set gravity acceleration threshold value, the processor starts to store the test data of the accelerometer of the inertia measurement unit until the target shaft of the rotary table rotates to a preset axial position, so as to obtain a plurality of test data corresponding to the same preset axial position;
and screening the plurality of test data corresponding to the same preset axial position to obtain the measurement data matched with the preset axial position.
4. The automatic calibration method according to claim 3, wherein the number of the target axes of the turntable is plural, and the rotation of each target axis is sequentially adjusted to a preset axial position to obtain the measurement data of the accelerometer of the inertial measurement unit in the positive X-axis direction, the negative X-axis direction, the positive Y-axis direction, the negative Y-axis direction, the positive Z-axis direction and the negative Z-axis direction, respectively.
5. The automatic calibration method according to any one of claims 1 to 4, wherein the fitting of the preset calibration points to the test data by the processor based on the calibration program to obtain calibration parameters, and storing the calibration parameters in a memory of the inertial system to be calibrated, so as to compensate the inertial measurement unit according to the calibration parameters comprises:
the processor calculates the reference data corresponding to the preset calibration point and the test data by a least square method based on the calibration program to obtain a scale factor and an offset;
and storing the scale factor and the offset into a memory of the inertial system to be measured so as to compensate the inertial measurement unit.
6. The automatic calibration method according to any one of claims 1 to 4, further comprising:
after the calibration parameters are obtained, the rotary table is adjusted again to operate under the preset calibration point in sequence;
the processor compensates the data collected by the inertia measurement unit according to the calibration parameters to obtain compensated compensation data;
comparing the compensation data with reference data corresponding to the preset calibration point;
and when the difference between the compensation data and the reference data corresponding to the preset calibration point is smaller than a specified threshold value, taking the calibration parameter as a target calibration parameter.
7. The automatic calibration method according to claim 6, further comprising:
when the difference between the compensation data and the reference data corresponding to the preset calibration point is not less than a specified threshold value, the inertial measurement unit is calibrated again until the difference between the compensation data and the reference data corresponding to the preset calibration point is less than the specified threshold value.
8. The automatic calibration method according to claim 6, further comprising:
when the difference between the compensation data and the reference data corresponding to the preset calibration point is not less than a specified threshold value, the inertial measurement unit is calibrated again within a set calibration frequency, and if the inertial measurement unit cannot meet retest conditions all the time, the inertial measurement unit is marked as a suspected fault product so as to perform fault judgment.
9. The automatic calibration program according to any one of claims 1 to 4, wherein the calibration program pre-programmed in the processor includes calibration points matching the inertial measurement unit to be measured.
10. An automatic calibration system for an inertial measurement unit, the automatic calibration system comprising: the system comprises a rotary table and a control cabinet, wherein the control cabinet is connected with the rotary table, an inertia measuring unit to be tested and a processor form an inertia system to be calibrated, the inertia system to be calibrated is arranged on the rotary table, and a calibration program is burnt in the processor in advance;
the control cabinet, the rotary table and the inertial system to be calibrated are matched with each other to realize the automatic calibration method as claimed in any one of claims 1 to 9.
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