CN109813336A - Inertial measurement unit calibration method - Google Patents

Abstract

The present invention relates to a kind of scaling methods of Inertial Measurement Unit, are applied to nine axis Inertial Measurement Units, the nine axis Inertial Measurement Unit includes three-axis gyroscope, three axis accelerometer and three axle magnetometer.The scaling method of the Inertial Measurement Unit includes: to provide three axis turntables and clamping part；The nine axis Inertial Measurement Unit is installed in the clamping part；The clamping part is installed in the three axis turntable；Control three axis turntable rotation, and record nine axis Inertial Measurement Units detection data, while the gyroscope, the accelerometer and the magnetometer are calibrated.The scaling method of above-mentioned Inertial Measurement Unit, cost is relatively low and precision is higher for calibration.The embodiment of the present invention also provides a kind of scaling method of controller, applied to the controller including nine axis Inertial Measurement Units.

Description

Inertial measurement unit calibration method

technical field

The invention relates to the technical field of sensors, in particular to a calibration method for an inertial measurement unit.

Background technique

Unmanned aerial vehicles, robots, mechanical gimbals, vehicles and ships, virtual reality/augmented reality, and human motion analysis have all achieved rapid development in recent years. In these applications, the autonomous measurement of 3D attitude and orientation is extremely important. Inertial measurement unit (Inertial measurement unit, IMU), as a sensor for measuring the three-axis attitude angle of an object, is an important component for realizing the above technologies and equipment. Especially in the development of the virtual reality/augmented reality industry, virtual reality/augmented reality equipment not only needs to satisfy the user's viewing of content, but also needs to communicate between the virtual world and the real world through attitude sensors, so that the virtual world can be connected to the virtual world through real devices. operation and control.

The traditional inertial measurement unit includes two sensors: a gyroscope (Gyroscope) and an accelerometer (Accelerometer). . In order to obtain more accurate attitude data, a nine-axis inertial measurement unit is currently being developed. On the basis of the traditional inertial measurement unit, the nine-axis inertial measurement unit adds another sensor: the magnetometer (Magnetometer) to the Yaw direction of the attitude. to compensate. Due to the deviation of the hardware manufacturing process of the three sensors of the nine-axis inertial measurement unit, the data of the sensors will have a certain deviation when sensing the outside world. Therefore, the inertial measurement unit needs to be calibrated to achieve the consistency of sensor perception data. Require. Because the measurement properties of the three sensors are different, different sensors need to be calibrated in different ways. At present, people mainly use the following methods to calibrate the nine-axis inertial measurement unit:

1) Manual calibration method: simple and quick to use, but it is necessary to use special fixtures and jigs to clamp the sensors of the nine-axis inertial measurement unit. The manual calibration method relies heavily on manual operation, is prone to errors, and has low precision, is prone to misoperation, cannot be mass-produced and controlled, and has high calibration costs and low efficiency.

2) Machine calibration method: The inertial measurement unit is calibrated by using a traditional three-axis turntable, which can improve the calibration speed and accuracy. However, this method can only calibrate the gyroscope and accelerometer of the nine-axis inertial measurement unit, and cannot be used for the calibration of the magnetometer.

3) Turn 8 method: The magnetometer is manually calibrated, but only a single magnetometer can be calibrated, and the calibration effect is inconsistent, and the calibration quality cannot define the test.

All in all, the current calibration method of the nine-axis inertial measurement unit has the problems of cumbersome operation, insufficient precision and low efficiency.

SUMMARY OF THE INVENTION

The purpose of the embodiments of the present invention is to provide a nine-axis inertial measurement unit with low cost and high precision, so as to solve the above technical problems.

A method for calibrating an inertial measurement unit is applied to a nine-axis inertial measurement unit, wherein the nine-axis inertial measurement unit includes a three-axis gyroscope, a three-axis accelerometer, and a three-axis magnetometer. The calibration method of the inertial measurement unit includes: providing a three-axis rotary table and a clamping part; installing the nine-axis inertial measurement unit in the clamping part; installing the clamping part in the three-axis inertial measurement unit; and controlling the rotation of the three-axis rotating table, recording the detection data of the nine-axis inertial measurement unit, and calibrating the gyroscope, the accelerometer and the magnetometer at the same time.

In one embodiment, after the fixture is installed on the three-axis rotary table, a controller is provided, and the controller is wirelessly connected with the nine-axis inertial measurement unit in the fixture connection; the controller is used for controlling the rotation of the three-axis turntable, and for calibrating the gyroscope, the accelerometer and the magnetometer.

In one of the embodiments, when calibrating the gyroscope, the static deviation of the gyroscope on its three axes is calibrated.

In one embodiment, when calibrating the static deviation of the gyroscope on its three axes, the gyroscope is placed in the three-axis rotary table with different predetermined attitudes and left for a predetermined time; The detected data of the gyroscope in different attitudes is calculated, and the static deviation of the gyroscope in different attitudes is calculated respectively, and the gyroscope is calibrated after the static deviation of the gyroscope is saved.

In one of the embodiments, when calibrating the gyroscope, the static deviation and the rotational distortion deviation of the gyroscope are calibrated at the same time.

In one embodiment, the accelerometer is calibrated and the offset of each axis of the accelerometer is calibrated.

In one embodiment, calibrating the offset of each axis of the accelerometer includes:

placing the clamps in the three-axis rotary table with different predetermined attitudes and leaving them for a predetermined time;

Respectively obtain the data detected by the accelerometer under each attitude; further, in order to improve the stability and accuracy of detection and calibration, multiple groups of data can be collected, and the average of all data detected under each attitude is calculated separately. value, as the data detected by the accelerometer in this attitude;

Calculate the center points of the positive and negative data of the three axes of the accelerometer respectively, so as to obtain the center of the measurement range, that is, the offset of each axis;

After saving the offset for each axis of the gyroscope, the gyroscope is calibrated.

In one of the embodiments, the magnetometer is calibrated, and the bias and scale of the magnetometer are calibrated.

In one embodiment, calibrating the deviation and scale of the magnetometer includes: rotating the magnetometer so that the magnetometer forms a spherical shape in space, and the three axes of the magnetometer obtained by the rotation are in three-dimensional coordinates The maximum and minimum values of the magnetic strength, the deviation of the magnetometer is calculated, and the magnetometer is calibrated according to the deviation.

In one embodiment, when the three-axis rotary table is provided, the magnetic field strength inside the three-axis rotary table is set to be less than or equal to 0.6 Guass.

In one of the embodiments, the three-axis turntable is made of non-magnetic conductive material.

In one embodiment, a plurality of accommodating cavities are provided in the clamping member, and the accommodating cavities are used for accommodating the nine-axis inertial measurement unit; the nine-axis inertial measurement unit is installed in the In the clamping piece, a plurality of the nine-axis inertial measurement units are simultaneously installed in the accommodating cavity of the clamping piece.

In one embodiment, the detection parameters of the nine-axis inertial measurement unit are tested, and if the test meets the requirements, the process ends, and if the detection does not meet the requirements, the nine-axis inertial measurement unit continues to be calibrated until the test results meet the requirements .

In one embodiment, when testing the detection parameters of the nine-axis inertial measurement unit, the static jitter accuracy, rotational positioning accuracy, convergence speed, static drift, dynamic drift, and rotation axis of the nine-axis inertial measurement unit are respectively tested partial.

In one embodiment, testing the detection parameters of the nine-axis inertial measurement unit includes: simultaneously testing the static jitter accuracy, rotational positioning accuracy, and static drift of the nine-axis inertial measurement unit.

In one of the embodiments, testing the detection parameters of the nine-axis inertial measurement unit further includes simultaneously testing the dynamic drift and rotational axis deflection of the nine-axis inertial measurement unit.

Embodiments of the present invention further provide a calibration method for a control device, which is applied to a control device including a nine-axis inertial measurement unit, where the nine-axis inertial measurement unit includes a three-axis gyroscope, a three-axis accelerometer, and a three-axis magnetic force. The calibration method of the inertial measurement unit includes: providing a three-axis rotary table and a clamping part; installing the control device in the clamping part; installing the clamping part on the three-axis rotary table ; And control the rotation of the three-axis rotary table, and record the detection data of the control device, while calibrating the gyroscope, the accelerometer and the magnetometer

Compared with the prior art, the calibration method of the inertial measurement unit provided by the embodiment of the present invention breaks through the limitation of the calibration of the conventional inertial measurement unit, and can use the three-axis rotary table and the clamping member to simultaneously align multiple inertial measurement units. It is installed and calibrated, and the gyroscope, accelerometer and magnetometer are calibrated at the same time, which effectively improves the calibration efficiency and accuracy of the nine-axis inertial measurement unit.

Description of drawings

In order to illustrate the technical solutions of the present invention more clearly, the following will briefly introduce the accompanying drawings used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention, which are common in the art. As far as technical personnel are concerned, other drawings can also be obtained based on these drawings without any creative effort.

1 is a schematic flowchart of a calibration method for an inertial measurement unit provided by an embodiment of the present invention;

FIG. 2 is a schematic diagram of functional modules of a nine-axis inertial measurement unit provided by an embodiment of the present invention.

Fig. 3 is the schematic diagram of the three-axis rotary table in the calibration method of the inertial measurement unit shown in Fig. 1;

Fig. 4 is the schematic diagram of the clamping member in the calibration method of the inertial measurement unit shown in Fig. 1;

Fig. 5 is a schematic diagram of one group of attitudes of the clamping member in the calibration method of the inertial measurement unit shown in Fig. 1;

Fig. 6 is the schematic diagram of another group of attitudes of the clamping member in the calibration method of the inertial measurement unit shown in Fig. 1;

FIG. 7 is a schematic view of the reading of the magnetometer of the inertial measurement unit shown in FIG. 1 during the calibration process.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Referring to FIG. 1 , an embodiment of the present invention provides a method for calibrating an inertial measurement unit, which is applied to the calibration of the nine-axis inertial measurement unit 100 shown in FIG. 2 .

The nine-axis inertial measurement unit 100 includes a gyroscope 10 , an accelerometer 30 and a magnetometer 50 . The gyroscope 10 is a three-axis gyroscope, which is used to detect the three-axis angular velocity. The accelerometer 30 is a triaxial accelerometer, which is used to detect triaxial acceleration. The magnetometer 50 is a three-axis magnetometer, which is used to detect the strength of the three-axis magnetic field.

The nine-axis inertial measurement unit 100 can be applied to devices that need to detect motion or static posture, such as intelligent mobile terminals (such as mobile phones, tablet computers, smart watches, etc.), remote control handles, game handles, somatosensory devices, unmanned aerial vehicles, etc. . Due to the manufacturing process, the nine-axis inertial measurement unit 100 may have a measurement deviation problem when it leaves the factory or is assembled in the above-mentioned device. In order to improve the stability of the output data of the nine-axis inertial measurement unit 100 and accuracy, and to verify whether the performance of the nine-axis inertial measurement unit 100 meets the application standards, the nine-axis inertial measurement unit 100 or a device equipped with the nine-axis inertial measurement unit 100 needs to be calibrated and calibrated.

During the research process of the invention, the inventor found that when using the traditional manual calibration method, the six-axis inertial measurement unit calibration method or the figure-of-eight method to calibrate the nine-axis inertial measurement unit 100, there are common problems of cumbersome operation and high accuracy. Insufficient and low-efficiency problems, so the inventor is devoted to improving the calibration accuracy and calibration efficiency of the nine-axis inertial measurement unit 100 . In the course of the above research, the inventor's research includes:

1) The gyroscope 10 is used to measure the angular velocity. Before calibration, the zero point reading and the reading linear scale relationship are inconsistent, so the zero point center and the reading scale of the gyroscope need to be calibrated.

2) The accelerometer 30 is used to measure the acceleration of the object, mainly in the form of force. Before the calibration, the measurement center point may have inconsistent offset, and there will be a certain angle deviation between the axis and the axis, so the center and scale of the accelerometer need to be calibrated.

3) The magnetometer 50 is used for measuring the strength of the magnetic field, and by measuring the strength of the geomagnetic field, the north direction of the geomagnetism is calculated. The inventor found that, since the magnetometer 50 will be affected by the electronic device itself and the electromagnetic field during the layout and patching, a fixed magnetic force is formed inside the electronic product, and other external electronic products may also appear. Magnetic field effects, such as transformers, motors, magnetized iron supplies, etc., may have the effect of magnetic fields. Therefore, it is necessary to calibrate the internal and external magnetic fields to eliminate the influence of various magnetic fields on the magnetometer measurement. The center point and scale of the magnetometer will be affected by these internal and external magnetic fields, and it needs to be calibrated.

In view of the above problems, embodiments of the present invention provide the above-mentioned inertial measurement unit calibration method, which is used to improve the calibration accuracy and calibration efficiency of the nine-axis inertial measurement unit 100 .

Please refer to FIG. 1 again. Specifically, in the embodiment shown in FIG. 1 , the inertial measurement unit calibration method includes the steps:

Step S101: Provide a three-axis rotary table.

Please refer to FIG. 3 at the same time. Specifically, in some embodiments, a three-axis rotary table 200 as shown in FIG. 3 is provided. The three-axis rotary table 200 includes a base frame 210 , a first rotation mechanism 230 , a second rotation mechanism 250 and a third rotation mechanism 270 .

The first rotation mechanism 230 includes a first drive member (not shown in the figure) connected to the base frame 210 , a first turntable 231 connected to the first drive member, and a first turntable 231 connected to the first turntable 231 . The support frame 233 is used to drive the first turntable 231 and the support frame 233 to rotate relative to the base frame 210 around the first axis Z. In this embodiment, the first axis Z is a vertical axis. In some specific embodiments, the first driving member may be a motor.

The second rotation mechanism 250 includes a second drive member (not shown in the figure) connected to the support frame 233 and a second turntable 251 connected to the second drive member. The second turntable 251 is driven to rotate relative to the support frame 233 around a second axis Y, wherein the second axis Y is perpendicular to the first axis Z. In this embodiment, the second axis Y is a horizontal axis. In some specific embodiments, the second driving member may be a motor.

The third rotation mechanism 270 includes a third driving member 271 connected to the second turntable 251 , and the third driving member 271 is used to drive the nine-axis inertial measurement unit 100 to be detected to rotate relative to the second turntable 251 . The third axis X rotates, the third axis X is perpendicular to the first axis Z and the second axis Y at the same time, that is, the first axis Z, the second axis Y and the third axis The axes X are in an orthogonal state. In this embodiment, the third axis X is a horizontal axis. In some specific embodiments, the third driving member 271 may be a rotary cylinder.

In order to avoid magnetic interference to the nine-axis inertial measurement unit 100, the three-axis rotary table 200 is made of non-magnetic conductive materials, such as aluminum materials, alloy materials, and the like. Further, when both the first driving member and the second driving member are motors, the first driving member should be at a first preset distance from the second driving member, in other words, the first driving member There is a first preset distance from the second driving member, and the first preset distance is greater than or equal to 50 cm.

In some embodiments, in order to avoid magnetic interference to the nine-axis inertial measurement unit 100 , when the three-axis rotary table 200 is provided, the magnetic field strength inside the three-axis rotary table 200 is set to be less than or equal to 0.6 Guass.

Step S103: Provide a fixture, and install the device with the nine-axis inertial measurement unit in the fixture.

In this embodiment, a clamping member 400 as shown in FIG. 4 is provided. The clamping member 400 is provided with a plurality of accommodating cavities 410, which can simultaneously accommodate a plurality of devices having the nine-axis inertial measurement unit. It can be understood that, in other embodiments, when calibrating a device equipped with the nine-axis inertial measurement unit, the clamping member may include one or more accommodating cavities adapted to the device.

In some embodiments, the clamping member is a polyhedral box, preferably, the clamping member is a hexahedral box (such as a rectangular parallelepiped, a cube) as shown in FIG. The device can also have a well-defined installation orientation when installed in the fixture when calibrated. Further, in order to enable the clamping member to conveniently record its posture in the subsequent calibration process, a three-dimensional Cartesian coordinate system can be established for the clamping member, as shown in FIG. The coordinate system includes two mutually orthogonal x-axis, y-axis and z-axis.

Step S105: Install the clamping member on the three-axis rotary table. Specifically, the clamping member is connected to the third driving member of the three-axis rotary table, so that the third driving member can drive the clamping member to rotate around the third axis X.

Step S107: Provide a controller to wirelessly connect the controller with the nine-axis inertial measurement unit in the fixture. The controller is wirelessly connected and communicated with the nine-axis inertial measurement unit, and the controller can acquire detection data of the nine-axis inertial measurement unit in real time.

Step S109: Control the rotation of the three-axis rotary table, and record the detection data of the nine-axis inertial measurement unit, so as to calibrate the nine-axis inertial measurement unit.

Specifically, in some embodiments, when calibrating the nine-axis inertial measurement unit, the gyroscope, the accelerometer and the magnetometer are calibrated simultaneously. Step S109 includes:

Step S1091: Calibrate the gyroscope. Specifically, in this implementation manner, when calibrating the gyroscope, the static deviation of the gyroscope on its three axes is calibrated: the gyroscope is placed at rest in different predetermined attitudes for a predetermined time respectively; the gyroscope is obtained separately The data detected in different attitudes are calculated, and the static deviations of the gyroscopes under different attitudes are calculated respectively, and the gyroscopes are calibrated after the static deviations of the gyroscopes are saved. In this embodiment, when the gyroscope is at rest, the static deviation of the gyroscope is reflected in the data detected by the gyroscope. In order to improve the stability and accuracy of detection and calibration, multiple sets of data can be collected and an average value of multiple sets of data can be obtained to calculate the static deviation of the gyroscope on the three axes. Further, please refer to FIG. 5 at the same time, the clamping members are respectively placed at rest in different attitudes, and the static deviation of the nine-axis inertial measurement unit in the clamping member under different attitudes is detected. The above different postures include: placing the x-axis of the clamping part vertically, placing the y-axis of the clamping part vertically, and placing the z-axis of the clamping part vertically.

Specifically in this embodiment, the step refinement includes:

The clamping member is allowed to stand for a predetermined time in a first predetermined posture, and the first predetermined posture is a posture in which the x-axis of the clamping member is placed vertically; wherein, the x-axis of the clamping member can be along the The positive direction of gravitational acceleration can also be in the opposite direction of gravitational acceleration;

Obtain the detected data of the gyroscope, and calculate the first static deviation of the gyroscope; in this embodiment, when the gyroscope is stationary, the static deviation of the gyroscope is reflected in the detected in the data. In order to improve the stability and accuracy of detection and calibration, multiple sets of data can be collected and the average value of multiple sets of data can be collected to more accurately calculate the first static deviation of the gyroscope;

The clamping member is allowed to stand for a predetermined time in a second predetermined posture, and the second predetermined posture is a posture in which the y-axis of the clamping member is placed vertically; wherein, the y-axis of the clamping member can be along the The positive direction of gravitational acceleration can also be in the opposite direction of gravitational acceleration;

Obtain the detected data of the gyroscope, and calculate the second static deviation of the gyroscope; in order to improve the stability and accuracy of detection and calibration, multiple sets of data can be collected and the average value of multiple sets of data can be collected to compare accurately calculating a second static bias of the gyroscope;

The clamping member is allowed to stand for a predetermined time in a third predetermined posture, and the third predetermined posture is a posture in which the z-axis of the clamping member is placed vertically; wherein, the z-axis of the clamping member can be along the The positive direction of gravitational acceleration can also be in the opposite direction of gravitational acceleration;

Obtain the detected data of the gyroscope, and calculate the third static deviation of the gyroscope; in order to improve the stability and accuracy of detection and calibration, multiple sets of data can be collected and the average value of multiple sets of data can be collected to compare accurately calculating a third static bias of the gyroscope;

The first, second and third static biases of the gyroscope are saved and the gyroscope is calibrated.

In some other embodiments, in order to improve the calibration accuracy of the gyroscope, the static bias and the rotational distortion bias of the gyroscope can be calibrated at the same time. When calibrating the rotational distortion deviation of the gyroscope, the clamping member is placed in the three-axis rotary table and rotated according to a predetermined direction, and the rotational distortion deviation of the gyroscope is reflected in the detected data. In order to improve the stability and accuracy of detection and calibration, multiple sets of data can be collected to calculate the rotational distortion deviation of the gyroscope on three axes.

Further, please refer to FIG. 5 at the same time. Similar to the above-mentioned method of calibrating static deviation, the clamping member is rotated in different attitudes, and the rotational distortion deviation of the clamping member under different attitudes is detected to obtain the gyro. The gyroscope is calibrated after the rotation distortion deviation of the gyroscope on its three axes is stored, and the gyroscope rotation distortion deviation is saved. The above-mentioned different postures include: placing the x-axis of the clamping piece vertically and rotating around x circles, placing the y-axis of the clamping piece vertically and rotating around y circles, and placing the clamping piece vertically. The z-axis of the piece is placed vertically and rotated around the z-circle. Further, when rotating the clamping part, it rotates at a constant speed.

Step S1093: Calibrate the accelerometer. Specifically, in this embodiment, the accelerometer is calibrated, and the offset of each axis of the accelerometer is calibrated. Specifically, this step includes:

The clamping members are respectively placed in different predetermined postures for a predetermined time; wherein, please refer to FIG. 6 at the same time, different predetermined postures include placing the x-axis of the clamping member along the positive direction of gravitational acceleration, placing the The y-axis of the fixture is placed along the positive direction of the acceleration of gravity, the z-axis of the fixture is placed along the positive direction of the acceleration of gravity, the x-axis is placed in the opposite direction of the acceleration of gravity, and the y-axis of the fixture is placed along the positive direction of the acceleration of gravity. Place along the opposite direction of the gravitational acceleration, and place the z-axis of the clamping piece along the opposite direction of the gravitational acceleration; further, when placing the clamping piece, place the clamping piece strictly according to the predetermined attitude, so as to Each direction of the hardware of the accelerometer can be placed horizontally, so as to avoid the adverse effect of the gravitational acceleration on the accelerometer, thereby improving the calibration accuracy.

Respectively obtain the data detected by the accelerometer under each attitude; further, in order to improve the stability and accuracy of detection and calibration, multiple groups of data can be collected, and the average of all data detected under each attitude is calculated separately. value, as the data detected by the accelerometer in this attitude;

Calculate the center points of the positive and negative data of the three axes of the accelerometer respectively, so as to obtain the center of the measurement range, that is, the offset of each axis;

After saving the offset for each axis of the gyroscope, the gyroscope is calibrated.

Specifically in this embodiment, the above-mentioned step refinement includes:

Step SZ101: the clamping member is left to stand for a predetermined time in a first positive predetermined posture, and the first positive predetermined posture is a posture in which the x-axis of the clamping member is placed vertically; wherein, the clamping member is The x-axis is set along the positive direction of gravitational acceleration;

Step SZ102: Acquire the data detected by the accelerometer; further, in order to improve the stability and accuracy of detection and calibration, multiple sets of data can be collected, and the average value of all the detected data can be calculated as the first positive predetermined the data detected by the accelerometer in the attitude;

Step SZ103: leaving the clamping member in a first negative predetermined posture for a predetermined time, and the first negative predetermined posture is a posture in which the x-axis of the clamping member is placed vertically; wherein, the clamping member The x-axis is set in the opposite direction of gravitational acceleration;

Step SZ104: Obtain the data detected by the accelerometer; further, in order to improve the stability and accuracy of detection and calibration, multiple sets of data can be collected, and the average value of all the detected data can be calculated as the first negative predetermined. the data detected by the accelerometer in the attitude;

Step SZ105: Calculate the center point of the data detected by the accelerometer under the first positive predetermined attitude and the data detected by the accelerometer under the first negative predetermined attitude, as the offset of the x-axis;

Step SZ106: save the offset of the x-axis of the gyroscope, and calibrate the gyroscope;

Step SZ107: the clamping member is left to stand for a predetermined time in a second positive predetermined posture, and the second positive predetermined posture is a posture in which the y-axis of the clamping member is placed vertically; wherein, the clamping member is The y-axis of is set along the positive direction of gravitational acceleration;

Step SZ108: Obtain the data detected by the accelerometer; further, in order to improve the stability and accuracy of detection and calibration, multiple sets of data can be collected, and the average value of all the detected data can be calculated as the second positive predetermined. the data detected by the accelerometer in the attitude;

Step SZ109 : the clamping member is placed in a second negative predetermined posture for a predetermined time, and the second negative predetermined posture is a posture in which the y-axis of the clamping member is vertically placed; wherein, the clamping member is The y-axis of the piece is set in the opposite direction of the gravitational acceleration;

Step SZ110: Acquire the data detected by the accelerometer; further, in order to improve the stability and accuracy of detection and calibration, multiple sets of data can be collected, and the average value of all the detected data can be calculated as the second negative predetermined the data detected by the accelerometer in the attitude;

Step SZ111: Calculate the center point of the data detected by the accelerometer under the second positive predetermined attitude and the data detected by the accelerometer under the second negative predetermined attitude, as the offset of the y-axis;

Step SZ112: save the offset of the y-axis of the gyroscope, and calibrate the gyroscope;

Step SZ113 : the clamping member is placed in a third positive predetermined posture for a predetermined time, and the third positive predetermined posture is a posture in which the z-axis of the clamping member is vertically placed; wherein the clamping member is The z-axis of the piece is set along the positive direction of gravitational acceleration;

Step SZ114: Obtain the data detected by the accelerometer; further, in order to improve the stability and accuracy of detection and calibration, multiple sets of data can be collected, and the average value of all the detected data can be calculated as the third positive predetermined. the data detected by the accelerometer in the attitude;

Step SZ115 : the clamping member is placed in a third negative predetermined posture for a predetermined time, and the third negative predetermined posture is a posture in which the z-axis of the clamping member is vertically placed; wherein the clamping member is The z-axis of the piece is set along the opposite direction of gravitational acceleration;

Step SZ116: Acquire the data detected by the accelerometer; further, in order to improve the stability and accuracy of detection and calibration, multiple sets of data can be collected, and the average value of all the detected data can be calculated as the third negative predetermined. the data detected by the accelerometer in the attitude;

Step SZ117: Calculate the center point of the data detected by the accelerometer under the third positive predetermined attitude and the data detected by the accelerometer under the third negative predetermined attitude, as the offset of the z-axis;

Step SZ118: Save the offset of the z-axis of the gyroscope, and calibrate the gyroscope.

In some other implementations, in order to improve the calibration accuracy of the accelerometer, each axis offset and scale deviation of the accelerometer can be calibrated at the same time. Further, in some embodiments, after calibrating the accelerometer, after saving the detected parameters by rotating in six directions, the offset and scale calculation formulas are used to calculate, and the scale deviation is the twist deflection parameter of each axis.

Step S1095: Calibrate the magnetometer. Specifically, in this embodiment, the magnetometer is calibrated, and the deviation and scale of the magnetometer are calibrated. Specifically, this step includes:

Rotate the magnetometer to make the reading of the magnetometer roughly form a spherical shape in the three-dimensional coordinate space, as shown in Figure 7;

The deviation of the magnetometer is calculated according to the maximum and minimum values of the magnetic force in the three-dimensional coordinates of the three axes of the magnetometer obtained by rotation; wherein, the maximum value of the above-mentioned magnetic force is the direction with the strongest magnetic field, and the minimum value of the magnetic force is the magnetic field. reverse. Because the strength of the geomagnetic field is only 50-60mGauss, and the range of the magnetometer is much larger than the strength of the geomagnetic field, in the presence of only the geomagnetic field, the magnetic strength reading of the magnetometer will have a maximum and minimum value.

The magnetometer is calibrated according to the offset.

In other embodiments, the magnetometer is calibrated using ellipse fitting.

Step S111: control the turntable to rotate to the test position, test the detection parameters of the nine-axis inertial measurement unit, if the test meets the requirements, then end, if the detection does not meet the requirements, then execute step S109, until the nine-axis inertial measurement unit test The result meets the requirements. Specifically, this step includes:

Step S1111: Test the static jitter accuracy of the nine-axis inertial measurement unit, and further test the static jitter of the nine-axis inertial measurement unit under the six predetermined attitudes shown in FIG. 6, when the jitter is less than or equal to 0.05 degrees , the static jitter accuracy test of the nine-axis inertial measurement unit passed.

Specifically, the jitter accuracy describes the stability of the fine operation of the inertial measurement unit. Since the gyroscope itself has its own accuracy, the compensation for the gyroscope should not exceed its own fine operation accuracy. Since the jitter data mainly describes the stability of the subtle operation of the inertial measurement unit, the smaller the jitter, the more subtle rotational motion can be seen. The data analysis of static jitter is to describe the jitter situation by collecting the average value of multiple data points at different points, and calculating the standard deviation of each point. The acquisition of static jitter data, positioning through the rotation angle, every N degrees (for example, in some embodiments, a point every 4 degrees, a total of 45 points), for each positioning point, calculate the data of 50 static points. standard deviation. For all n data, the average jitter distance is calculated as:

Among them, d _i is the degree of the current frame, and the greater the average deviation, the greater the jitter.

Step S1112: Test the rotation positioning accuracy of the nine-axis inertial measurement unit, and further test the rotation error of the nine-axis inertial measurement unit when it rotates around its three axes in 45-degree steps. When the rotation error is less than or equal to At 1 degree, the rotation positioning accuracy test of the nine-axis inertial measurement unit is passed.

Specifically, the rotational positioning accuracy is the accuracy of each position of the nine-axis inertial measurement unit when the nine-axis inertial measurement unit rotates in different directions, with the northeast as the reference position, and the parameter Describes how accurately the orientation of the nine-axis inertial measurement unit is restored. The rotation positioning accuracy is obtained through the three-axis rotary table to obtain the rotation position, and then the data is calculated by the nine-axis inertial measurement unit. The average deviation is used to calculate the rotational positioning accuracy of the nine-axis inertial measurement unit.

For example, in some specific embodiments, the data acquisition of the rotational positioning accuracy includes the step of: dividing the three axes into fixed-angle rotational positions, every N degrees (for example, a point every 45 degrees, a total of 8 points) , through the rotation of the rotary table to locate M points, the angle at which the inertial measurement unit is rotated to this point is obtained, and then the data is calibrated by the rotation origin alignment, so that the angle of each inertial measurement unit is consistent with the angle of the rotary table, and the inertial measurement unit is calculated. The rotational positioning deviation between the angle of the measuring unit and the actual angle of the turntable is:

in, is the angle of the i-th rotary table, is the angle of the i-th inertial measurement unit. The larger the rotational positioning deviation of the inertial measurement unit, the worse the accuracy of restoring the original angle. Step S1113: Test the convergence speed of the nine-axis inertial measurement unit, and further test the nine-axis inertial measurement unit to rotate around its three axes with different step angles and rotation speeds, and then stop the rotation. The convergence angle and time of the nine-axis inertial measurement unit. When the convergence angle is less than or equal to 1 degree, and the convergence time is less than or equal to 200ms, the convergence test of the nine-axis inertial measurement unit passes.

Specifically, the convergence accuracy is a comprehensive parameter that describes the data acquisition speed, transmission efficiency and fusion algorithm solution speed of the inertial measurement unit. The positioning speed of the inertial measurement unit depends on the size of the speed. When the same rotary table moves with the same amplitude, the higher the speed, the faster the convergence speed, the faster the convergence speed, and the faster the virtual position returns to the handle position, which reduces the delay and improves the response speed. However, due to the problem of jitter in some solutions, in the process of returning to positive, the tail will have a certain rotation process, but the faster the convergence speed, the more difficult the rotation process is to detect.

The convergence data mainly analyzes the return speed of the inertial measurement unit in the solution. The data is obtained by continuously recording the data changes during the motion of the rotating table of the inertial measurement unit. By calculating the rate of data change, the convergence speed of the inertial measurement unit solution is calculated. The speed of the data depends on the data generation speed of the sensor on the one hand, and the algorithm solution speed on the other hand. The convergence speed measures the convergence speed of the data generated by the combination of the two.

Test different speeds on the three axes, in the case of the same step, the ratio of the movement time of the system to the stop time, calculate the time proportion of the system in the movement process, so as to estimate the convergence time of the system. According to the same movement in the same direction of movement and static time, the rotary table is used to move around three axes in three directions, and each data of the system during the movement process is stored. The proportion of the convergence time is (N%-50%)*time/2, which is the convergence time.

In another embodiment, the time when the system moves to a standstill is calculated, and the time is defined as the convergence time, but the time includes the system operation time and data transmission time, and the final calculated convergence time needs to exclude the system operation time and data. transfer time.

Step S1114: test the static drift of the nine-axis inertial measurement unit, further, test the data drift of the nine-axis inertial measurement unit when it is stationary under the six predetermined attitudes shown in FIG. 6, when the data drift is less than or When equal to 1 degree/min, the static drift test of the nine-axis inertial measurement unit passes.

Specifically, in some embodiments, the static drift tests the degree by which the inertial measurement unit deviates from the starting position after being stationary for a period of time. On the stage, leave it for a certain time, for example, 1 minute, 5 minutes, 10 minutes, 30 minutes, 60 minutes. After placement, take the IMU reading and compare it to the starting position to get the deviation from static drift.

Step S1115: Test the dynamic drift of the nine-axis inertial measurement unit, and further, test the nine-axis inertial measurement unit to rotate around its three axes with different step angles and rotation speeds, and then stop the rotation. The speed and time that the nine-axis inertial measurement unit continues to move. When the movement speed is less than or equal to 0.1 degrees/second, and the movement time is less than or equal to 200ms, the dynamic drift test of the nine-axis inertial measurement unit is passed.

Specifically, the static drift tests the degree by which the inertial measurement unit deviates from the starting position after a long period of motion. The test method starts from a point, such as the origin, and continuously rotates around three axes through the turntable to time As a benchmark, after testing different time rotations, when the inertial measurement unit returns to the starting point position, the deviation of its reading from the original starting point reading is used as the accuracy of static drift.

Step S1116: Test the rotation axis deviation of the nine-axis inertial measurement unit, and further test the axis deviation generated when the nine-axis inertial measurement unit rotates around its three axes at different speeds. When the axis is too small At or equal to 1 degree, the rotation axis deflection test of the nine-axis inertial measurement unit passes.

Specifically, the rotation axis deflection calculates the deflection between the axis and the axis of the inertial measurement unit during the rotation process. Ideally, when the inertial measurement unit rotates around a certain axis, the reading of the axis should be stable, but Due to the problems of the device and the solution algorithm, its axes may not be parallel, which will lead to the situation of axis deviation. If the axis deviation is too large, it will affect the user's experience.

In the test of the rotation axis deviation, the rotating table continuously rotates around the three axes to obtain the reading of the axis during the rotation process, and calculate its standard deviation and maximum deviation, which are the average deviation and the maximum deviation of the axis.

In some embodiments provided by the present invention, when the above-mentioned test step S111 is performed, in the test process of steps S1111 to S1116, one or more of the steps can be tested in parallel, or each step can be tested one by one. The order of precedence is not limited to the numbering restrictions described above. For example, in another embodiment of the present invention, when performing the above-mentioned test step S111, the static jitter accuracy test, the rotational positioning accuracy test, and the static drift test are integrated into one test step S115; the dynamic drift test and the rotation axis deviation test are integrated. A test step S117 is integrated to form a production line test solution with two-step test steps, so as to reduce the test time and improve the production efficiency. In some embodiments, specific test steps are performed as follows:

Step S115: Simultaneously test the static jitter accuracy, rotational positioning accuracy, and static drift of the nine-axis inertial measurement unit. Specifically, in the three-axis direction, every 45 degrees is used as the test angle, and the three-axis is divided into 8+8+4, a test process of a total of 20 test points. For each fixed point, 5 seconds of data are stored, and the mean and standard deviation are calculated. The standard deviation (jitter accuracy) of the 20 sample positions is averaged as the static jitter accuracy of the system. Calculate the total offset between the system position and the rotating platform by making the difference between the angle of the 20 points and the angle of the rotating platform, then add the total offset to each point to get the offset of each position point, and finally calculate 20 samples The average offset of the point is used for the rotation positioning accuracy. At the same time, the maximum deviation of each point is calculated as the size of the static drift, and the average deviation of 20 sample points is calculated as the static drift accuracy.

Step S117: Simultaneously test the dynamic drift and rotational axis deflection of the nine-axis inertial measurement unit. Specifically, rotate around three axes respectively, and each axis rotates for 20 seconds; record the starting position of the three axes, and stop to the starting position after rotating for 20 seconds; store the Euler angle data for 20 seconds, and calculate the standard of the rotating axis The difference is used as the rotation axis deviation accuracy; the maximum deviation of each axis is calculated, which is the most dynamic drift size.

In other embodiments provided by the present invention, when performing the above-mentioned test step S111, in the test process of steps S1111 to S1116, one or more of the steps can be subjected to a simplified test, and the sequence of the test steps is not limited to The numbering restrictions described above. For example, in another embodiment of the present invention, when performing the above-mentioned test step S111, the specific test steps are performed as follows:

Step S1191: Test the static jitter accuracy of the nine-axis inertial measurement unit. Further, the handle can be rotated on a plane to check the jitter condition. When it is judged that the jitter amplitude is greater than a preset value, the test fails. Further, when the jitter is less than or equal to 0.05 degrees, the static jitter accuracy test of the nine-axis inertial measurement unit is passed.

Step S1192: Test the rotation positioning accuracy of the nine-axis inertial measurement unit. Further, you can manually rotate 90 degrees to see how large the deviation of the 90-degree data is. When it is judged that the deviation is greater than the preset value, the test fails. Further, when the rotation error is less than or equal to 1 degree, the rotation positioning accuracy test of the nine-axis inertial measurement unit is passed.

Step S1193: Test the static drift of the nine-axis inertial measurement unit. Further, it can be directly placed on the table, the Euler angle of the initial position can be recorded, and after a period of time, the data can be read again to obtain the size of its static drift. Further, when the data drift is less than or equal to 1 degree, the static drift test of the nine-axis inertial measurement unit is passed.

Step S1194: test the dynamic drift of the nine-axis inertial measurement unit, further, through the method of emergency stop, it can move back and forth, and then stop suddenly, and then observe whether each axis drifts after the motion is stationary, and the data increases In the case of reduction, if the drift is too large, it is considered not to pass. Further, when the data drift is less than or equal to 15 degrees, the dynamic drift test of the nine-axis inertial measurement unit is passed.

Step S1195: Test the rotation axis deviation of the nine-axis inertial measurement unit. Further, rotate the handle around three axes to see the direction of the three axes. When rotating, whether the axis is relatively deviated, and if the rotation direction and rotation If the axis is too large, it is considered not to pass. Further, when the axis deviation is less than or equal to 1 degree, the rotation axis deviation test of the nine-axis inertial measurement unit is passed.

The above-mentioned simplification of the test steps can achieve the effect of rapid verification, which can allow the R&D personnel to understand the corresponding relationship between the test parameters and the physical quantities in the actual application scene after the test, and through some specific phenomena, it is more convenient to judge the nine Whether the performance of the axis inertial measurement unit is qualified or not improves the detection efficiency of the nine-axis inertial measurement unit.

An embodiment of the present invention further provides a control device, the control device includes the above-mentioned nine-axis inertial measurement unit, and the control device can emit light to allow a machine vision device to recognize. At the same time, the present invention also provides a calibration method for a control device equipped with a nine-axis inertial measurement unit, and the calibration method is used for calibrating and testing the nine-axis inertial measurement unit of the control device. The calibration method of the control device equipped with the nine-axis inertial measurement unit is roughly the same as the calibration method of the above-mentioned inertial measurement unit, and the difference lies in:

When calibrating the control device, the entire control device equipped with the nine-axis inertial measurement unit is installed in a suitable fixture, and the nine-axis inertial measurement unit in the control device is calibrated and tested .

The calibration method of the inertial measurement unit provided by the embodiment of the present invention breaks through the limitation of the calibration of the conventional inertial measurement unit. The gyroscope, accelerometer and magnetometer are calibrated at the same time during calibration, which effectively improves the efficiency and accuracy of the calibration of the nine-axis inertial measurement unit.

In the description of this specification, description with reference to the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples", etc., mean specific features described in connection with the embodiment or example , structure, material or feature is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily directed 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, those skilled in the art may combine and combine the different embodiments or examples described in this specification, as well as the features of the different embodiments or examples, without conflicting each other.

In addition, the terms "first" and "second" are only used for descriptive purposes, and should not be construed as indicating or implying relative importance or implying the number of indicated technical features. Thus, a feature delimited with "first", "second" may expressly or implicitly include at least one of that feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise expressly and specifically defined.

Any description of a process or method in the flowcharts or otherwise described herein may be understood to represent a module, segment or portion of code comprising one or more executable instructions for implementing a specified logical function or step of the process , and the scope of the preferred embodiments of the present invention includes alternative implementations in which the functions may be performed out of the order shown or discussed, including performing the functions substantially concurrently or in the reverse order depending upon the functions involved, which should It is understood by those skilled in the art to which the embodiments of the present invention belong.

The logic and/or steps represented in flowcharts or otherwise described herein, for example, may be considered an ordered listing of executable instructions for implementing the logical functions, may be embodied in any computer-readable medium, For use with, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a system including a processor, or other system that can fetch instructions from and execute instructions from an instruction execution system, apparatus, or apparatus) or equipment. For the purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport the program for use by or in connection with an instruction execution system, apparatus, or apparatus.

More specific examples (non-exhaustive list) of computer readable media include the following: electrical connections with one or more wiring (mobile terminals), portable computer disk cartridges (magnetic devices), random access memory (RAM), Read Only Memory (ROM), Erasable Editable Read Only Memory (EPROM or Flash Memory), Fiber Optic Devices, and Portable Compact Disc Read Only Memory (CDROM). In addition, the computer readable medium may even be paper or other suitable medium on which the program may be printed, as the paper or other medium may be optically scanned, for example, followed by editing, interpretation, or other suitable medium as necessary process to obtain the program electronically and then store it in computer memory.

It should be understood that various parts of the present invention may be implemented in hardware, software, firmware or a combination thereof. In the above-described embodiments, various steps or methods may be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented by any one or a combination of the following techniques known in the art: Discrete logic circuits, application specific integrated circuits with suitable combinational logic gates, Programmable Gate Arrays (PGA), Field Programmable Gate Arrays (FPGA), etc.

Those skilled in the art can understand that all or part of the steps carried by the methods of the above embodiments can be completed by instructing the relevant hardware through a program, and the program can be stored in a computer-readable storage medium, and the program can be stored in a computer-readable storage medium. When executed, one or a combination of the steps of the method embodiment is included. In addition, each functional unit in each embodiment of the present invention may be integrated into one processing module, or each unit may exist physically alone, or two or more units may be integrated into one module. The above-mentioned integrated modules can be implemented in the form of hardware, and can also be implemented in the form of software function modules. If the integrated modules are implemented in the form of software functional modules and sold or used as independent products, they may also be stored in a computer-readable storage medium.

The above-mentioned storage medium may be a read-only memory, a magnetic disk or an optical disk, and the like. Although the embodiments of the present invention have been shown and described above, it should be understood that the above-mentioned embodiments are exemplary and should not be construed as limiting the present invention. Embodiments are subject to variations, modifications, substitutions and variations.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand: it can still be The technical solutions described in the foregoing embodiments are modified, or some technical features thereof are equivalently replaced; and these modifications or replacements do not drive the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (10)

1. The calibration method of the inertial measurement unit is characterized by being applied to a nine-axis inertial measurement unit, wherein the nine-axis inertial measurement unit comprises a three-axis gyroscope, a three-axis accelerometer and a three-axis magnetometer; the calibration method of the inertial measurement unit comprises the following steps:

providing a three-axis rotating platform and a clamping piece;

installing the nine-axis inertia measurement unit in the clamping piece;

installing the clamping piece on the three-axis rotating table; and

and controlling the three-axis rotating platform to rotate, recording detection data of the nine-axis inertia measurement unit, and calibrating the gyroscope, the accelerometer and the magnetometer.

2. The method for calibrating an inertial measurement unit according to claim 1, wherein after the clamping member is mounted on the three-axis rotating table, a controller is provided, and the controller is wirelessly connected with the nine-axis inertial measurement unit in the clamping member; the controller is configured to control the rotation of the three axis rotation stage and to calibrate the gyroscope, the accelerometer, and the magnetometer.

3. A method of calibrating an inertial measurement unit according to claim 2, wherein the gyroscope is calibrated by calibrating the static offset of the gyroscope in its three axes;

when the static deviation of the gyroscope on the three axes of the gyroscope is calibrated, the gyroscope is respectively placed in the three-axis rotating table in different preset postures and is kept still for preset time; respectively acquiring the detected data of the gyroscope in different postures, respectively calculating the static deviation of the gyroscope in different postures, and calibrating the gyroscope after storing the static deviation of the gyroscope.

4. A calibration method for an inertial measurement unit according to claim 2, characterized in that, when calibrating the gyroscope, the static deviation and the rotational distortion deviation of the gyroscope are calibrated simultaneously;

calibrating the accelerometer, calibrating the offset of each axis of the accelerometer;

calibrating the offset of each axis of the accelerometer, comprising:

placing the clamping pieces in different preset postures in the three-axis rotating table respectively and standing for preset time;

respectively acquiring data detected by the accelerometer under each posture; furthermore, in order to improve the stability and accuracy of detection and calibration, multiple groups of data can be collected, and the average value of all the data detected in each attitude is calculated respectively and used as the data detected by the accelerometer in the attitude;

respectively calculating the central points of positive and negative data of three axes of the accelerometer, thereby obtaining the center of a measuring range, namely the offset of each axis;

after the offset of each axis of the gyroscope is saved, the gyroscope is calibrated.

5. A method of calibrating an inertial measurement unit according to claim 2, wherein the magnetometers are calibrated, the magnetometers are calibrated for bias and scale;

calibrating bias and scale for the magnetometer, comprising: and rotating the magnetometer to enable the magnetometer to form a spherical shape in space, calculating the deviation of the magnetometer according to the maximum and minimum values of the magnetic strength of the three axes of the rotated magnetometer in three-dimensional coordinates, and calibrating the magnetometer according to the deviation.

6. A calibration method for an inertial measurement unit according to claim 1, wherein when the three-axis rotating table is provided, the magnetic field strength inside the three-axis rotating table is made less than or equal to 0.6 Guass; the three-axis turntable is made of a non-magnetic conductive material.

7. The method for calibrating an inertial measurement unit according to claim 1, wherein a plurality of receiving cavities are provided in the clamping member, the receiving cavities being configured to receive the nine-axis inertial measurement unit; and when the nine-axis inertia measurement unit is arranged in the clamping piece, the nine-axis inertia measurement units are simultaneously arranged in the accommodating cavity of the clamping piece.

8. The method for calibrating an inertial measurement unit according to claim 1, wherein the test parameters of the nine-axis inertial measurement unit are tested, and if the test meets the requirements, the test is terminated, and if the test does not meet the requirements, the nine-axis inertial measurement unit is continuously calibrated until the test results meet the requirements.

9. The method for calibrating an inertial measurement unit according to claim 8, wherein when testing the detection parameters of the nine-axis inertial measurement unit, the nine-axis inertial measurement unit is tested for static jitter accuracy, rotational positioning accuracy, convergence speed, static drift, dynamic drift, and rotational misalignment;

or, testing the detection parameters of the nine-axis inertial measurement unit, including: and simultaneously testing the static shaking precision, the rotation positioning precision, the static drift, the dynamic drift and the rotation shaft deflection of the nine-shaft inertia measurement unit.

10. The calibration method of the control equipment is characterized by being applied to the control equipment comprising a nine-axis inertial measurement unit, wherein the nine-axis inertial measurement unit comprises a three-axis gyroscope, a three-axis accelerometer and a three-axis magnetometer; the calibration method of the inertial measurement unit comprises the following steps:

providing a three-axis rotating platform and a clamping piece;

installing the control equipment in the clamping piece;

installing the clamping piece on the three-axis rotating table; and

and controlling the three-axis rotating platform to rotate, recording detection data of the control equipment, and calibrating the gyroscope, the accelerometer and the magnetometer.