CN112129320B - Method and system for full-automatic calibration of MEMS-IMU sensor of unmanned aerial vehicle - Google Patents

Method and system for full-automatic calibration of MEMS-IMU sensor of unmanned aerial vehicle Download PDF

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CN112129320B
CN112129320B CN202010826434.2A CN202010826434A CN112129320B CN 112129320 B CN112129320 B CN 112129320B CN 202010826434 A CN202010826434 A CN 202010826434A CN 112129320 B CN112129320 B CN 112129320B
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accel
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徐进
宋勋
丁显
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Luneng New Energy Group Co ltd
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Abstract

The invention discloses a full-automatic calibration method for an unmanned aerial vehicle MEMS-IMU sensor, which comprises the following steps: s1, dividing the temperature range to be calibrated by taking the room temperature as a dividing point; s2, calibrating at room temperature and obtaining calibration data; s3, specifically, the method comprises the following steps: s30, determining the changed temperature, and judging whether the temperature exceeds the temperature interval; s31, if yes, completing calibration; s32, if not, compensating and calculating the data at the changed temperature, and judging whether the data is smaller than an error threshold value; s33, if yes, go to step S30; if not, calibration is performed using the new calibration point as a new calibration point, calibration data is obtained, and the process proceeds to step S30. The invention discloses a system for fully automatically calibrating an unmanned aerial vehicle MEMS-IMU sensor. The method has the advantages of realizing less calibration of an approximate linear region which is not influenced by temperature greatly, reducing the repeated labor cost and avoiding the problem of large error caused by the conventional segmented calibration.

Description

Method and system for full-automatic calibration of unmanned aerial vehicle MEMS-IMU sensor
Technical Field
The invention relates to the technical field of unmanned aerial vehicle MEMS-IMU sensor calibration. More specifically, the invention relates to a method and a system for full-automatic calibration of an unmanned aerial vehicle MEMS-IMU sensor, which are mainly used for rapid and accurate initial calibration of an Inertial Measurement Unit (IMU) of an unmanned aerial vehicle flight controller.
Background
The micro-electro-mechanical system (MEMS) of the drone comprises a MEMS-IMU sensor (inertial measurement unit (IMU)), the IMU comprising a three-axis accelerometer and a three-axis gyroscope for detecting independent three-axis acceleration and angular velocity of the carrier relative to an inertial coordinate system, and a corresponding embedded processing program that can solve the attitude of the object according to the measured angular velocity and acceleration of the object in three-dimensional space.
The MEMS-IMU sensor is low in price and small in size, and is widely applied to the fields of navigation, unmanned aerial vehicles, VR, robots, intelligent hand rings and the like, for example, MPU6050 commonly used by consumer-grade unmanned aerial vehicles, but the consistency of the IMU is poor due to environmental factors, processing errors, device differences and the like, and the influence of temperature change on the IMU sensor is particularly obvious, so that the calibration of the MEMS-IMU is particularly important. When present unmanned aerial vehicle flight control ware carries out full temperature section calibration, there is the problem that the duplication of labor cost is high, the error is big.
Disclosure of Invention
It is an object of the present invention to address at least the above problems and to provide at least the advantages described hereinafter.
The invention also aims to provide a method for fully automatically calibrating the MEMS-IMU sensor of the unmanned aerial vehicle, which realizes few calibration in an approximate linear area which is not influenced by temperature greatly, reduces the repeated labor cost and avoids the problem of large error caused by the conventional segmented calibration.
The invention also aims to provide a system for fully automatically calibrating the MEMS-IMU sensor of the unmanned aerial vehicle, and a fully-automatic calibration device.
To achieve these objects and other advantages in accordance with the purpose of the invention, as embodied and broadly described herein, there is provided a method for fully automatic calibration of an unmanned aerial vehicle MEMS-IMU sensor, comprising the steps of:
s1, dividing the temperature range to be calibrated into two temperature intervals by taking the room temperature as a demarcation point;
s2, calibrating the MEMS-IMU sensor meter at room temperature, and obtaining calibration data under the calibration point;
s3, determining a temperature interval for calibration, and calibrating the temperature interval, wherein the specific steps are as follows:
s30, determining the changed temperature by taking the current measured temperature as a temperature starting point and delta T as a temperature change value of two adjacent measurements, and judging whether the changed temperature exceeds the temperature interval;
s31, if yes, completing the calibration of the temperature interval;
s32, if not, the calibration data of the current calibration point is used for compensation and calculating the data of the MEMS-IMU sensor at the changed temperature, and whether the compensated data is smaller than an error threshold value is judged;
s33, if yes, go to step S30;
if not, the changed temperature is used as a new calibration point for calibration, calibration data at the temperature of the calibration point is obtained, and the step S30 is performed.
Preferably, the MEMS-IMU sensor includes a three-axis gyroscope and a three-axis accelerometer, and the calibrating the MEMS-IMU sensor in step S2 specifically includes calibrating the three-axis gyroscope and calibrating the three-axis accelerometer.
Preferably, the calibrating of the three-axis gyroscope is specifically:
keeping the MEMS-IMU sensor static at the temperature of the calibration point, continuously acquiring X-axis angular velocity data, Y-axis angular velocity data and Z-axis angular velocity data of the three-axis gyroscope for at least 100 times respectively, and then respectively calculating X-axis zero offset, Y-axis zero offset and Z-axis zero offset of the gyroscope corresponding to the average value;
calibrating the three-axis gyroscope according to the X-axis zero offset, the Y-axis zero offset and the Z-axis zero offset, and forming calibration data of the three-axis gyroscope at the calibration point temperature.
Preferably, the calibration of the three-axis accelerometer specifically includes:
establishing an error model Accel of the triaxial accelerometer, wherein Accel is Maccel*Saccel*(Accelimu-Biasaccel) Wherein M isaccelOrthogonality error for the three-axis accelerometer, SaccelIs the scale factor of a triaxial accelerometer, AccelimuFor the purpose of collecting triaxial accelerometer data, BiasaccelZero offset for a three-axis accelerometer;
continuously acquiring data of the triaxial accelerometer for at least 30 times at six positions respectively by adopting a hexahedral calibration method at the temperature of the calibration point, and then respectively calculating the average value to obtain Accel of the triaxial accelerometer at the six positionsimuData;
making P after matrix calculation of the error model Accelaccel＝Saccel -1*Maccel -1Write as an augmented matrix, Accelimu＝[Paccel|Biasaccel]Accel, Accel based on data from three-axis accelerometer at six positionsimuTo find PaccelLeast squares solution and zero-Bias ofaccel(ii) a Wherein the content of the first and second substances,
Figure BDA0002636358560000031
Figure BDA0002636358560000032
according to MaccelObtaining scale factor S of triaxial accelerometer with model-preserving propertyaccel；
According to Paccel＝Saccel -1*Maccel -1To obtain an orthogonality error Maccel；
According to a zero-BiasaccelScale factor SaccelOrthogonality error MaccelAnd calibrating the triaxial accelerometer, and forming calibration data of the triaxial accelerometer at the calibration point temperature.
Preferably, in step S32, the determining whether the compensated data is smaller than the error threshold specifically includes determining whether the compensated data of the three-axis gyroscope is smaller than the error threshold and determining whether the compensated data of the three-axis accelerometer is smaller than the error threshold, where the compensated data of the gyroscope is the true angular velocity of three axes of the three-axis gyroscope and the compensated data of the three-axis accelerometer is the component of the gravitational acceleration g in three axes.
Preferably, Δ T is 1 ℃.
Preferably, the error threshold of the data of the three-axis gyroscope is 0.2 degrees/s, and the error threshold of the data of the three-axis accelerometer is 0.01 g.
A system for full-automatic calibration of an unmanned aerial vehicle MEMS-IMU sensor comprises:
the sensor data acquisition unit is connected with the MEMS-IMU sensor and is used for acquiring data of the MEMS-IMU sensor;
the control and data processing unit is connected with the sensor data acquisition unit through a data transmission unit, and the sensor data acquisition unit transmits acquired data to the control and data processing unit through the data transmission unit;
the rotary table unit is connected with the control and data processing unit and used for receiving and executing the angle instruction sent by the control and data processing unit, wherein the MEMS-IMU sensor is arranged on the rotary table unit;
the automatic control constant temperature unit is connected with the control and data processing unit and used for receiving and executing the temperature instruction sent by the control and data processing unit, wherein the MEMS-IMU sensor is positioned in the temperature control range of the automatic control constant temperature unit;
the room temperature is used as a demarcation point, the temperature range to be calibrated is divided into two temperature intervals, and after a start instruction is received, the control and data processing unit control flow is set as follows:
sa, determining a temperature interval for calibration, calibrating the MEMS-IMU sensor meter at room temperature, and obtaining calibration data under the calibration point;
sb, taking the current measured temperature as a temperature starting point and delta T as temperature change values of two adjacent measurements, determining the temperature after change, and judging whether the temperature after change exceeds the temperature interval;
if the temperature interval is Sc, completing the calibration of the temperature interval;
if not, sending an expected temperature to the automatic control constant temperature unit, determining that the MEMS-IMU sensor reaches the expected temperature, sending an expected angle to the turntable unit, determining that the MEMS-IMU sensor reaches the expected angle, compensating according to calibration data of a current calibration point, calculating data of the MEMS-IMU sensor at the changed temperature, and judging whether the compensated data is smaller than an error threshold value or not;
se, if so, performing a step Sb;
if not, calibrating by taking the changed temperature as a new calibration point, obtaining calibration data at the temperature of the calibration point, and performing the step Sb.
Preferably, the automatic control constant temperature unit comprises a compressor unit and a temperature box connected with the compressor unit through a hose;
the turntable unit includes:
the platform assembly comprises a rotating motor, a placing platform and four leveling telescopic motors, wherein the rotating motor is arranged below the incubator, an output shaft of the rotating motor can rotatably penetrate through the bottom surface of the incubator, the placing platform is arranged in the incubator, the four leveling telescopic motors are arranged below the incubator, the output shaft of the leveling telescopic motors can movably penetrate through the bottom surface of the incubator, a driving groove with a non-cylindrical cross section is arranged in the center of the bottom surface of the placing platform, a driving rod matched with the telescopic groove is arranged at the top end of the rotating motor, the four leveling telescopic motors are arranged in a rectangular shape coaxially arranged with the placing platform along the circumferential direction, and an X-axis groove and a Y-axis groove are arranged on the top surface of the placing platform in a crossed concave shape;
the locking assembly comprises a pair of Y-axis guide plates which are respectively arranged at two ends of the placing platform along the X-axis direction, a pair of X-axis guide plates which are respectively arranged at two ends of the placing platform along the Y-axis direction, and the Y-axis guide plates and the X-axis guide plates which are adjacent to each other along the circumferential direction are detachably and fixedly connected, wherein a longitudinal section of a turnover groove which is not circular is recessed along the axial direction of the corresponding center on one X-axis guide plate and the Y-axis guide plate on one X-axis guide plate, a longitudinal section of a moving groove which is circular is recessed along the axial direction of the corresponding center on the other X-axis guide plate and the Y-axis guide plate on the other X-axis guide plate, and the bottom surface of the moving groove is made of an iron material;
the overturning component comprises an overturning motor which is positioned outside the incubator and close to one side of one overturning groove, a turbine which is fixedly arranged on an output shaft of the overturning motor, a worm which is meshed with the turbine and is arranged, and an overturning telescopic motor which is positioned outside the incubator and opposite to the overturning motor, wherein the output shaft of the worm can rotatably penetrate through the incubator and is matched with the overturning groove, the output shaft of the overturning telescopic motor can rotatably penetrate through the incubator and is matched with the moving groove, the output shaft of the worm, the output shaft of the overturning telescopic motor, the overturning groove which is opposite to the output shaft of the worm and the moving groove which is opposite to the overturning telescopic motor are coaxially arranged, the free end of the output shaft of the overturning telescopic motor is made of a magnetic material, wherein the magnetic connecting force of the output shaft of the overturning telescopic motor and the corresponding moving groove is smaller than the force of the worm for driving the MEMS-IMU sensor to overturn, and the turntable unit comprises a turntable unit which comprises a magnetic material :
the platform assembly comprises a rotating motor, a placing platform and four leveling telescopic motors, wherein the rotating motor is arranged below the incubator, an output shaft of the rotating motor can rotatably penetrate through the bottom surface of the incubator, the placing platform is arranged in the incubator, the four leveling telescopic motors are arranged below the incubator, the output shaft of the leveling telescopic motors can movably penetrate through the bottom surface of the incubator, a driving groove with a non-cylindrical cross section is arranged in the center of the bottom surface of the placing platform, a driving rod matched with the telescopic groove is arranged at the top end of the rotating motor, the four leveling telescopic motors are arranged in a rectangular shape coaxially arranged with the placing platform along the circumferential direction, an X-axis groove 21 and a Y-axis groove are formed in the top surface of the placing platform 2 in a concave mode, and the X-axis groove and the Y-axis groove are crossed in an L shape;
the locking assembly comprises a pair of Y-axis guide plates respectively positioned at two ends of the placing platform along the X-axis direction, a pair of X-axis guide plates respectively positioned at two ends of the placing platform along the Y-axis direction, and Y-axis guide plates and X-axis guide plates which are adjacent along the circumferential direction are detachably and fixedly connected to form a space for fixedly containing the MEMS-IMU sensor, the side lengths of the Y-axis guide plates and the X-axis guide plates are equal, so that the Y-axis guide plates and the X-axis guide plates are fixedly connected to form a cube body, one of the Y-axis guide plates and one of the X-axis guide plates is sunken along the direction corresponding to the central axis and provided with a turnover groove with a non-circular end face, the other X-axis guide plate and the other Y-axis guide plate are sunken along the direction corresponding to the central axis and provided with a moving groove with a circular end face, and the bottom face of the moving groove is made of ferrous materials;
the overturning assembly comprises an overturning motor which is positioned outside the incubator and close to one side of one overturning groove, a turbine which is fixedly arranged on an output shaft of the overturning motor, a worm which is meshed with the turbine, and an overturning telescopic motor which is positioned outside the incubator and is arranged on one side opposite to the overturning motor, wherein the output shaft of the worm can rotatably penetrate through the incubator and is matched with the turnover groove, the output shaft of the turnover telescopic motor can rotatably penetrate through the incubator and is matched with the moving groove, the output shaft of the worm, the output shaft of the turnover telescopic motor, the turnover groove opposite to the output shaft of the worm and the moving groove opposite to the turnover telescopic motor are coaxially arranged, the free end of the output shaft of the turnover telescopic motor is made of magnetic materials, the magnetic connecting force between the output shaft of the turnover telescopic motor and the corresponding moving groove is smaller than the force for driving the MEMS-IMU sensor to turn over by the worm.
The invention at least comprises the following beneficial effects:
firstly, the corresponding data of the MEMS-IMU sensor in the full temperature range are calculated automatically, the labor cost is reduced, the online automatic processing is realized, the efficiency is obviously improved, the human errors caused by human operation are avoided, the consistency of the MEMS-IMU sensor after calibration is ensured, and the calibration of the MEMS-IMU sensor of multiple unmanned aerial vehicles can be carried out at one time.
Secondly, calibration is carried out at room temperature, using theory (data drift is approximately linear in slight temperature change), and then room temperature is taken as a separation point, changing the temperature by taking 1 ℃ as a temperature change value, calculating the data after the temperature change by using compensation data at room temperature (calibration point), if the compensated data is less than the error threshold value, the temperature is continuously changed, if the compensated data is greater than the error threshold value, the calibration is carried out once at the temperature to form a new calibration point, then continuously judging until the calibration of the full-temperature section is realized, realizing the calibration of few approximate linear areas which are not influenced by the temperature greatly, reducing the effect of repeated labor cost, regarding the temperature interval of the approximate task as a black box, carrying out online judgment, and carrying out calibration processing until the error is greater than a threshold value, thereby avoiding the problem of large error caused by the conventional segmented calibration;
the method is characterized in that the unmanned aerial vehicle is basically in a small dynamic state, so that the triaxial acceleration gyroscope only calculates the triaxial angular velocity zero offset in a static state, the triaxial accelerometer only calculates the importance of the triaxial angular velocity zero offset to posture and position velocity correction, and a hexahedron calibration method is adopted to calculate the zero offset, the orthogonal error and the scale factor.
Thirdly, the rotary table unit is matched with the automatic control constant temperature unit to provide the required temperature environment for the MEMS-IMU sensor to be measured and correspond to the angle adjustment of 6 positions required by a hexahedron calibration method, and the MEMS-IMU sensor is directly positioned on the placing platform and is not rigidly connected with an external transmission part when in a final measurement state, so that the leveling effect is improved; furthermore, a working heating component (a motor and the like) is not arranged in the incubator, the temperature control stability of the incubator is improved, and the service life loss of the temperature change of the incubator to the heating component is reduced.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.
Drawings
Fig. 1 is a structural block diagram of a system for full-automatic calibration of an unmanned aerial vehicle MEMS-IMU sensor according to one embodiment of the present invention;
fig. 2 is a flowchart of a method for fully automatically calibrating an unmanned aerial vehicle MEMS-IMU sensor according to one embodiment of the present invention;
fig. 3 is a schematic structural view of a turntable unit according to one embodiment of the present invention;
fig. 4 is a schematic structural diagram of the placement platform according to one embodiment of the present invention.
The reference numerals are specifically: a rotating electrical machine 1; driving the rod 10; a placing platform 2; a carry-over groove 20; an X-axis groove 21; a Y-axis slot 22; leveling the telescopic motor 3; a Y-axis guide plate 4; a turnover groove 40; a moving groove 41; a turning motor 5; a turbine 6; a worm 7; the telescopic motor 8 is turned over.
Detailed Description
The present invention is further described in detail below with reference to examples so that those skilled in the art can practice the invention with reference to the description.
< example 1>
A full-automatic calibration method for an unmanned aerial vehicle MEMS-IMU sensor comprises the following steps:
s1, determining the temperature range to be calibrated, specifically-45-70 ℃;
determining the room temperature (the current indoor temperature) to be 25 ℃, taking the room temperature as a demarcation point, dividing the temperature range to be calibrated into two temperature ranges, wherein one temperature range is defined as a low-temperature range [ -45 ℃,25 ℃), and the other temperature range is defined as a high-temperature range [25 ℃,75 ℃;
s2, calibrating the MEMS-IMU sensor meter at room temperature, and obtaining calibration data under the calibration point;
s3, determining the temperature range to be calibrated as a low-temperature range [ -45 ℃,25 ℃), and calibrating the temperature range, specifically:
s30, determining a temperature after the change to be 24 ℃, with 25 ℃ as a temperature starting point and Δ T ═ 1 ℃ as a temperature change value (each time the temperature changes to decrease by 1 ℃ in a low-temperature range);
s31, the changed temperature does not exceed the low-temperature range;
s32, performing compensation according to the calibration data of the current calibration point (25 ℃), calculating the data of the MEMS-IMU sensor at 24 ℃, and judging whether the compensated data is smaller than an error threshold value;
s33, if yes, judging that the data drift caused by the temperature change of 24 ℃ relative to 25 ℃ meets the requirement, and directly compensating the data at 24 ℃ by using the compensation data at 25 ℃ without calibrating at 24 ℃;
s34, continuously cooling to 23 ℃ (the temperature is in a low-temperature range), compensating by the calibration data of the current calibration point (25 ℃), calculating the data of the MEMS-IMU sensor at the temperature of 23 ℃, and judging whether the compensated data is smaller than an error threshold value or not;
s35, if the data drift caused by the temperature change of 23 ℃ relative to 25 ℃ does not meet the requirement, the data at 23 ℃ cannot be directly compensated by the compensation data at 25 ℃, the 23 ℃ needs to be calibrated once again to obtain calibration data at 23 ℃, and a new calibration point is formed at 23 ℃;
s36, continuously cooling to 22 ℃ (the temperature is in a low-temperature range), compensating by the calibration data of the current calibration point (23 ℃) and calculating the data of the MEMS-IMU sensor at 22 ℃, and judging whether the compensated data is smaller than an error threshold value or not;
……
sn, continuously cooling to-45 ℃ (in a low-temperature range), compensating by using calibration data of a previous calibration point at-45 ℃, calculating data of the MEMS-IMU sensor at-45 ℃, and judging whether the compensated data is smaller than an error threshold value or not;
sn +1, if yes, judging that the data drift caused by the temperature change of the-45 ℃ relative to the previous calibration point is approximately linear, and directly compensating the data at the time of-45 ℃ by using the compensation data of the previous calibration point without calibrating at the time of-45 ℃;
sn +2, continuously cooling to-46 ℃, and judging that the temperature is not in a low-temperature interval;
s4, calibrating the other temperature interval (the high temperature interval [25 ℃,75 ℃), specifically:
s40, with 25 ℃ as the starting point and Δ T ═ 1 ℃ as the temperature change value (1 ℃ rise per temperature change for the high temperature interval), determining the temperature after change to be 26 ℃;
s41, the changed temperature does not exceed the high-temperature interval;
s42, performing compensation according to the calibration data of the current calibration point (25 ℃), calculating the data of the MEMS-IMU sensor at 26 ℃, and judging whether the compensated data is smaller than an error threshold value;
s33, if yes, judging that the data drift caused by the temperature change of 26 ℃ relative to 25 ℃ meets the requirement, and directly compensating the data at 26 ℃ by using the compensation data at 25 ℃ without calibrating at 26 ℃;
s34, continuing to heat to 27 ℃ (in a low-temperature range), compensating by the calibration data of the current calibration point (25 ℃), calculating the data of the MEMS-IMU sensor at 27 ℃, and judging whether the compensated data is smaller than an error threshold value;
s35, if not, judging that the data drift caused by the temperature change of 27 ℃ relative to 25 ℃ is compared, if the data do not meet the requirement, the data at 27 ℃ cannot be directly compensated by the compensation data at 25 ℃, and the calibration data at 27 ℃ needs to be calibrated once again to obtain the calibration data at 27 ℃, wherein the 27 ℃ forms a new calibration point;
s36, continuing to heat to 28 ℃ (in a low-temperature range), compensating by the calibration data of the current calibration point (27 ℃), calculating the data of the MEMS-IMU sensor at 28 ℃, and judging whether the compensated data is smaller than an error threshold value;
……
sm, continuing to heat to 75 ℃ (in a low-temperature interval), compensating by using calibration data of the calibration point at the front temperature of 75 ℃, calculating data of the MEMS-IMU sensor at the temperature of 75 ℃, and judging whether the compensated data is smaller than an error threshold value;
sm +1, if yes, judging that the data drift caused by the temperature change of 75 ℃ relative to the previous calibration point is approximately linear, and directly compensating the data at 75 ℃ by using the compensation data of the previous calibration point without performing calibration at 75 ℃;
sm +2, continuously heating to 76 ℃, judging that the temperature is not in the high-temperature range, and finishing the calibration of the full-temperature section.
In the above embodiment, calibration is performed at room temperature, a theory is used (data drift is approximately linear in a slight change of temperature), then room temperature is used as a separation point, 1 ℃ is used as a temperature change value to change temperature (reduced temperature at an interval of 1 ℃ for a low-temperature interval, and increased temperature at an interval of 1 ℃ for a high-temperature interval), compensation data at room temperature (calibration point) is used to calculate data after temperature change, if the compensated data is smaller than an error threshold, temperature change is continued, if the compensated data is larger than the error threshold, calibration is performed once at the temperature to form a new calibration point, and then judgment is performed continuously until full-temperature calibration is realized, calibration in an approximately linear region with little influence of temperature is realized, labor cost is reduced, and a problem of large error caused by existing segmented calibration is avoided, and (4) regarding the approximate task temperature interval as a black box, and performing online judgment until the error is greater than a threshold value, and performing calibration processing.
< example 2>
A full-automatic calibration method for an unmanned aerial vehicle MEMS-IMU sensor comprises the following steps:
s1, determining the temperature range to be calibrated, specifically-55-100 ℃;
determining the room temperature (the current indoor temperature) to be 24 ℃, taking the room temperature as a demarcation point, dividing the temperature range to be calibrated into two temperature ranges, wherein one temperature range is defined as a low-temperature range [ -55 ℃,24 ℃), and the other temperature range is defined as a high-temperature range [24 ℃,100 ℃;
s2, calibrating the MEMS-IMU sensor meter at room temperature, and obtaining calibration data under the calibration point;
s3, determining the temperature interval for calibration as a low-temperature interval, and calibrating the temperature interval, specifically:
s30, determining a changed temperature by using the current measured temperature as a temperature starting point and Δ T ═ 1 ℃ as a temperature change value (a reduced temperature at an interval of 1 ℃) between two adjacent measurements, and determining whether the changed temperature exceeds the temperature range;
s31, if yes, completing the calibration of the temperature interval, and performing step S4;
s32, if not, the calibration data of the current calibration point is used for compensation and the data of the MEMS-IMU sensor under the changed temperature is calculated, and whether the compensated data is smaller than an error threshold value or not is judged;
s33, if yes, go to step S30;
if not, calibrating by taking the changed temperature as a new calibration point, obtaining calibration data at the temperature of the calibration point, and performing step S30;
s4, determining that the temperature interval for calibration is a high-temperature interval, and calibrating the temperature interval, specifically:
s40, taking the current measured temperature as a temperature starting point and delta T as temperature change values (rising temperature at an interval of 1 ℃) of two adjacent measurements, determining the temperature after the change, and judging whether the temperature after the change exceeds the temperature interval;
s41, if yes, completing the calibration of the whole temperature interval;
s42, if not, the calibration data of the current calibration point is used for compensation and calculating the data of the MEMS-IMU sensor at the changed temperature, and whether the compensated data is smaller than an error threshold value is judged;
s43, if yes, go to step S40;
if not, calibrating by taking the changed temperature as a new calibration point, obtaining calibration data at the temperature of the calibration point, and performing step S40;
the calibration of the MEMS-IMU sensor in the step S2 specifically comprises the calibration of the triaxial gyroscope and the calibration of the triaxial accelerometer;
the calibration of the three-axis gyroscope specifically comprises the following steps:
under the adjusted temperature point, a static placement averaging method is adopted, namely, the MEMS-IMU sensor of the unmanned aerial vehicle is kept static, data of an X axis, a Y axis and a Z axis of the three-axis gyroscope are continuously collected for 100 times respectively, and corresponding averages are respectively obtained to obtain three-axis zero offset values of the gyroscope, wherein the three-axis zero offset values are shown in formulas (1), (2) and (3):
Figure BDA0002636358560000101
Figure BDA0002636358560000102
Figure BDA0002636358560000103
wherein, Gyrox，GyroyAnd GyrozX-axis angular velocity data, Y-axis angular velocity data, Z-axis angular velocity data, Bias data, output by a three-axis gyroscope of an MEMS-IMU sensor in a static stategyrox，BiasgyroyAnd BiasgyrozThe angular speed of an X axis of the three-axis gyroscope is zero offset, the angular speed of a Y axis of the three-axis gyroscope is zero offset, and the angular speed of a Z axis of the three-axis gyroscope is zero offset;
when the adjusted temperature point is the calibration point, calibrating the temperature point, and using the X-axis angular velocity zero offset, the Y-axis angular velocity zero offset and the Z-axis angular velocity zero offset as calibration data corresponding to the calibration point of the three-axis gyroscope;
when the adjusted temperature point is a non-calibration point, compensating the acquired three-axis gyroscope by using calibration data of the calibration point corresponding to the temperature point, and calculating compensated data (the true angular velocities of three axes of the three-axis gyroscope, namely the true angular velocity of the X axis, the true angular velocity of the Y axis and the true angular velocity of the Z axis);
the calibration of the triaxial accelerometer specifically comprises the following steps:
and (4) establishing an accelerometer error model as shown in the formula (4).
Accel＝Maccel*Saccel*(Accelimu-Biasaccel) Formula (4)
Wherein Accel is the true value of the triaxial acceleration (i.e. the component of the gravitational acceleration g in three axes) in the static state, as shown in formula (5),
Figure BDA0002636358560000111
Maccelis the orthogonality error of the triaxial accelerometer, as shown in equation (6),
Figure BDA0002636358560000112
Saccelis the scale factor of the triaxial accelerometer, as shown in equation (7),
Figure BDA0002636358560000113
Accelimuthe three-axis accelerometer data collected by the MEMS-IMU accelerometer in the static state is shown in the formula (8),
Figure BDA0002636358560000114
Biasaccelis the zero offset of the triaxial accelerometer, as shown in equation (9).
Figure BDA0002636358560000115
Known from the accelerometer error model, AccelimuOnly need to calculate Maccel，SaccelAnd BiasaccelThus, the value of Accel can be obtained, and equation (10) can be obtained by matrix calculation using equation (4):
Accelimu＝(Maccel*Saccel)-1*Accel+Biasaccel＝Saccel -1*Maccel -1*Accel+Biasaccelformula (10)
Let Paccel＝Saccel -1*Maccel -1Then, then
Figure BDA0002636358560000116
Written as an augmentation matrix, as shown in equation (11):
Accelimu＝[Paccel|Biasaccel]accel formula (11)
Wherein the content of the first and second substances,
Figure BDA0002636358560000121
adopting a hexahedron calibration method, namely respectively placing the sensors at six positions of upward X axis, downward X axis, upward Y axis, downward Y axis, upward Z axis and downward Z axis, respectively and continuously acquiring the data of the triaxial accelerometer at the six positions for 30 times, respectively calculating the average value to obtain the data Accel of the triaxial acceleration at the six positionsimu；
According to the principle of gravity, neglecting the rotation and revolution of the earth, when the object is placed still, the object can be subjected to the vertical downward direction with the size of about 9.806m/s2G, so that Accel is obtained when the X-axis is directed downwardsx＝g，Accely＝0，AccelzBy analogy with 0, it is possible to obtain,
Figure BDA0002636358560000122
averaging Accel of triaxial acceleration acquired at six positionsimuCarry over to formula (11) to determine PaccelLeast squares solution of (3) and BiasaccelAnd then according to the orthogonality error matrix MaccelThe property of preserving the modulus (i.e. the modulus of each column is 1) can be used to obtain the scale factor S of the tri-axial accelerometeraccelAs shown in the formula 12,
Figure BDA0002636358560000123
then according to Paccel＝Saccel -1*Maccel -1Then M is obtainedaccel＝Paccel -1*Saccel -1。
To obtain the MEMS-IMU accelerometer sensorZero Bias of (triaxial accelerometer)accelOrthogonality error MaccelAnd a scale factor SaccelAnd then Accel is obtained;
when the adjusted temperature point is the calibration point, calibrating the temperature point, and then using BiasaccelOrthogonality error MaccelAnd a scale factor SaccelThe calibration data corresponding to the calibration points of the triaxial accelerometer are used;
and when the adjusted temperature point is a non-calibration point, compensating the acquired triaxial accelerometer by using calibration data of the calibration point corresponding to the temperature point, and calculating compensated data (triaxial real acceleration data, namely the component of the gravity acceleration g in three axes).
In the above embodiment, it is considered that the unmanned aerial vehicle is basically in a small dynamic state, so that only the three-axis angular velocity zero offset in a static state is calculated for the three-axis acceleration gyroscope, and the importance of the three-axis acceleration gyroscope on posture and position velocity correction is considered for the three-axis acceleration gyroscope, and the zero offset, the orthogonal error and the scale factor are calculated by adopting a hexahedron calibration method.
As shown in fig. 1-4, the present invention provides a system for fully automatically calibrating an unmanned aerial vehicle MEMS-IMU sensor, comprising:
the sensor data acquisition unit is connected with the MEMS-IMU sensor and is used for acquiring data of the MEMS-IMU sensor, and the sensor data acquisition unit specifically comprises data of a three-axis gyroscope and a three-axis accelerometer;
the control and data processing unit is connected with the sensor data acquisition unit through the data transmission unit, and the sensor data acquisition unit transmits acquired data to the control and data processing unit through the data transmission unit, wherein the acquired data can be transmitted in a wired or wireless mode and transmitted by adopting but not limited to a TTL serial port;
the rotating platform unit is connected with the control and data processing unit and used for receiving and executing angle instructions sent by the control and data processing unit, wherein the MEMS-IMU sensor is arranged on the rotating platform unit, the rotating platform unit can particularly realize the omnidirectional rotation of the platform by mainly rotating through two motors which are distributed orthogonally, and the angle of the motor is acquired through a motor encoder to carry out feedback control, so that the platform is ensured to accurately rotate to a desired angle sent by the control and data processing unit, and the MEMS-IMU sensor is ensured to obtain data at different angles;
the automatic control constant temperature unit is connected with the control and data processing unit and used for receiving and executing the temperature instruction sent by the control and data processing unit, wherein the MEMS-IMU sensor is positioned in the temperature control range of the automatic control constant temperature unit and is mainly used for responding to the expected temperature sent by the control and data processing unit and ensuring that the temperature is in a stable state, so that the MEMS-IMU sensor is calibrated at different temperatures;
wherein, carry out horizontal calibration to the spirit level for the platform that is used for installing the revolving stage unit, confirm the orthogonality of revolving stage diaxon, then fix sensor data acquisition unit (including MEMS-IMU sensor) on the platform of diaxon revolving stage unit, and confirm that sensor data acquisition unit is located automatic control constant temperature unit control range (place pivot platform cooperation sensor data acquisition unit whole in automatic control constant temperature unit, also can link firmly automatic control constant temperature unit on the platform of diaxon revolving stage unit), system circular telegram is initialized to accomplish the back, manual operation control and data processing unit send and begin to mark the instruction, the system begins full-automatic operation and marks the school task, after receiving and begins the instruction, the flow that the system automatic operation marks the school task is shown as figure 2, specifically do:
step 1, a control and data processing unit sends an expected temperature to a thermostat (an automatic control constant temperature unit);
step 2, automatically controlling a constant temperature unit to change the temperature of the constant temperature box to an expected temperature;
step 3, the control and data processing unit judges whether the temperature in the constant temperature box reaches the expected temperature or not through feedback temperature, if not, step 2 is carried out, and if yes, step 4 is carried out;
step 4, the control and data processing unit sends the expected angle to the rotary table unit;
step 5, changing the angle of the turntable unit to a desired angle;
step 6, the control and data processing unit judges whether the angle of the rotary table unit reaches the expected angle through the feedback angle, if not, the step 5 is carried out, and if so, the step 7 is carried out;
step 7, the control and data processing unit acquires data through the sensor data acquisition unit (the triaxial accelerometer is calibrated by adopting a hexahedron calibration method);
step 8, judging whether the six positions (the sensors are respectively placed at six positions of an X axis upwards, an X axis downwards, a Y axis upwards, a Y axis downwards, a Z axis upwards and a Z axis downwards) are completely collected, if not, performing step 6, and if so, performing step 9;
step 9, if the temperature is room temperature, calculating error calibration data at the temperature (step 2 and step 3 may not be performed);
if the temperature is not the room temperature, the calibration data of the calibration point corresponding to the temperature is used for compensation and calculating the data of the MEMS-IMU sensor at the temperature, whether the compensated data is smaller than an error threshold value or not is judged, if yes, the step 10 is carried out, and if not, the step 11 is carried out;
s10, taking the current measured temperature as a temperature starting point, taking delta T as a temperature change value of two adjacent measurements, determining the temperature after change, judging whether the temperature after change exceeds the temperature interval, if so, finishing calibration, and if not, performing the step 1;
and S11, calibrating by taking the changed temperature as a new calibration point, obtaining calibration data at the temperature of the calibration point, and performing the step 10.
In the above technical solution, the room temperature is used as a demarcation point, the temperature range to be calibrated is divided into two temperature intervals, and after receiving the start instruction, the control and data processing unit sets the control flow as:
sa, determining a temperature interval for calibration, calibrating the MEMS-IMU sensor meter at room temperature, and obtaining calibration data under the calibration point;
sb, taking the current measured temperature as a temperature starting point and delta T as temperature change values of two adjacent measurements, determining the temperature after change, and judging whether the temperature after change exceeds the temperature interval;
if the temperature interval is Sc, completing the calibration of the temperature interval;
if not, sending an expected temperature to the automatic control constant temperature unit, determining that the MEMS-IMU sensor reaches the expected temperature, sending an expected angle to the turntable unit, determining that the MEMS-IMU sensor reaches the expected angle, compensating by using calibration data of a current calibration point, calculating data of the MEMS-IMU sensor at the changed temperature, and judging whether the compensated data is smaller than an error threshold value or not;
se, if so, performing the step Sb;
if not, calibrating by taking the changed temperature as a new calibration point, obtaining calibration data at the temperature of the calibration point, and performing the step Sb; by adopting the technical scheme, the corresponding data of the MEMS-IMU sensor in the full temperature range are calculated in a full-automatic mode, the labor cost is reduced, the online automatic processing is realized, the efficiency is obviously improved, the human error caused by human operation is avoided, the consistency of the MEMS-IMU sensor after calibration is ensured, and the calibration can be carried out on the MEMS-IMU sensor of multiple unmanned aerial vehicles at one time.
In another technical scheme, the automatic control constant temperature unit comprises a compressor unit and a warm box connected with the compressor unit through a hose, the warm box is supported by a support, and the compressor unit works to control the temperature in the warm box in the working process;
the turntable unit includes:
the platform assembly comprises a rotating motor 1 which is arranged below the incubator and an output shaft of which can rotatably penetrate through the bottom surface of the incubator, a placing platform 2 which is arranged in the incubator, and four leveling telescopic motors 3 which are arranged below the incubator and output shafts of which can movably penetrate through the bottom surface of the incubator, wherein a driving groove 20 with a non-cylindrical cross section is arranged at the center of the bottom surface of the placing platform 2, a driving rod 10 which is matched with the telescopic groove is arranged at the top end of the rotating motor 1, the four leveling telescopic motors 3 are arranged in a rectangular shape which is coaxial with the placing platform 2 along the circumferential direction, an X-axis groove 21 and a Y-axis groove 22 are recessed in the top surface of the placing platform 2, and the X-axis groove and the Y-axis groove 22 are crossed in an L shape;
the locking assembly comprises a pair of Y-axis guide plates 4 which are respectively positioned at two ends of the placing platform 2 along the X-axis direction, a pair of X-axis guide plates which are respectively positioned at two ends of the placing platform 2 along the Y-axis direction, and the Y-axis guide plates 4 and the X-axis guide plates which are adjacent along the circumference are detachably and fixedly connected to form a space for fixedly containing the MEMS-IMU sensor, wherein the side lengths of the Y-axis guide plates and the X-axis guide plates are equal, so that the Y-axis guide plates and the X-axis guide plates are fixedly connected to form a cube, one of the Y-axis guide plates and one of the X-axis guide plates 4 is sunken along the direction corresponding to the central axis and is provided with an overturning groove 40 with a non-circular end surface, the other of the X-axis guide plate and the other Y-axis guide plate 4 are sunken along the direction corresponding to the central axis and are provided with a moving groove 41 with a circular end surface, and the bottom surface of the moving groove 41 is made of ferrous material;
the overturning component comprises an overturning motor 5 which is positioned outside the incubator and close to one side of one overturning groove 40, a turbine 6 which is fixedly arranged on an output shaft of the overturning motor 5, a worm 7 which is meshed with the turbine 6, and an overturning telescopic motor 8 which is positioned outside the incubator and is arranged on one side opposite to the overturning motor 5, wherein the output shaft of the worm 7 can rotatably penetrate through the incubator and is matched with the overturning groove 40, the output shaft of the overturning telescopic motor 8 can rotatably penetrate through the incubator and is matched with the moving groove 41, the output shaft of the worm 7, the output shaft of the overturning telescopic motor 8, the overturning groove 40 which is opposite to the output shaft of the worm 7 and the moving groove 41 which is opposite to the overturning telescopic motor 8 are coaxially arranged, and the free end of the output shaft of the overturning telescopic motor 8 is made of a magnetic material;
the X-axis groove 21 is arranged along the X-axis direction of the MEMS-IMU sensor, the Y-axis groove 22 is arranged along the Y-axis direction of the MEMS-IMU sensor, the X-axis guide plate is matched with the Y-axis guide plate 4 to realize the fixation of the MEMS-IMU sensor along the circumferential direction, the positioned X-axis guide plate, the corresponding overturning groove 40 and the corresponding moving groove 41 are all parallel to the X-axis groove 21, and the positioned Y-axis guide plate 4, the corresponding overturning groove 40 and the corresponding moving groove 41 are all parallel to the Y-axis groove 22;
when the four leveling telescopic motors 3 are contracted until the highest end of the output shaft is lower than the highest end of the output shaft connecting moving rod 10 of the rotating motor 1, the driving rod 10 of the rotating motor 1 is arranged in the driving groove 20 in a matching manner, the rotating motor 1 works to drive the placing platform 2 to rotate and adjust the relative positions of the X-axis groove 21, the Y-axis groove 22 and the overturning component, wherein the magnetic connecting force between the output shaft of the overturning telescopic motor 8 and the corresponding moving groove 41 is smaller than the force of the worm 7 driving the MEMS-IMU sensor to overturn.
In the using process, the method comprises the following steps:
installing a locking assembly;
placing an MEMS-IMU sensor in a groove body (an X-axis groove) on the top surface of a placing platform 2, enabling the X axis of the MEMS-IMU sensor to be parallel to the X-axis groove 21, enabling the Y axis to be parallel to the Y-axis groove 22, controlling four leveling telescopic motors 3 to level the placing platform 2, and enabling an overturning groove 40 and a moving groove 41 on a Y-axis guide plate to be coaxially arranged with an output shaft of a worm 7 and an output shaft of the overturning telescopic motor 8 respectively to achieve that the Z axis is upward;
the output shaft of the overturning telescopic motor 8 extends to enable the output shaft of the overturning telescopic motor 8 to be inserted into the corresponding moving groove 41 in a matching manner (the end part of the output shaft of the overturning telescopic motor 8 is in magnetic connection with the corresponding moving groove 41), the overturning telescopic motor 8 continues to extend to drive the MEMS-IMU sensor to move in the X-axis groove 21 (the overturning component is arranged on two sides of the Y-axis groove 22 along the length direction), the output shaft of the overturning motor 5 is arranged in the corresponding overturning groove 40 in a matching manner, the four leveling telescopic motors 3 are controlled to contract to provide a space for the overturning motor 5 to work to drive the MEMS-IMU sensor to overturn for 90 degrees (relative to a worm, the MEMS-IMU sensor rotates 90 degrees clockwise), after overturning, the leveling telescopic motors 3 extend to bear the overturned MEMS-IMU sensor, namely, the leveling telescopic motors 3 extend to drive the placing platform 2 to support the MEMS-IMU sensor, the telescopic motor 8 contracts to enable an output shaft of the telescopic motor to be separated from the moving groove 41 under the resistance of the groove wall of the X-axis groove 21, four leveling telescopic motors 3 are controlled to enable the placing platform 2 to be leveled, and a pair of overturning grooves 40 and the moving groove 41 are coaxially arranged with the output shaft of the worm 7 and the output shaft of the telescopic motor 8, so that the Y axis is upward;
the turning telescopic motor 8 extends to enable an output shaft of the turning telescopic motor 8 to be inserted into the corresponding moving groove 41 in a matching mode (the output shaft of the turning telescopic motor 8 is in magnetic connection with the corresponding moving groove 41), the turning telescopic motor 8 continues to extend to drive the MEMS-IMU sensor to move in the X-axis groove 21 (the turning component is arranged on two sides of the Y-axis groove 22 along the length direction), the output shaft of the turning motor 5 is arranged in the corresponding turning groove 40 in a matching mode, the four leveling telescopic motors 3 are controlled to contract to provide the turning motor 5 to work to drive the MEMS-IMU sensor to continue to turn for 90 degrees (clockwise continuous rotation is 90 degrees relative to the worm), the leveling telescopic motors 3 extend to receive the MEMS-IMU sensor after turning, namely the leveling telescopic motors 3 extend to drive the placing platform 2 to support the MEMS-IMU sensor, and the turning telescopic motor 8 contracts to enable the output shaft to be separated from the moving groove 41 under the resisting of the wall of the X-axis groove 21 Controlling four leveling telescopic motors 3 to level the placing platform 2, wherein a pair of overturning grooves 40 and a pair of moving grooves 41 are coaxially arranged with an output shaft of the worm 7 and an output shaft of the overturning telescopic motor 8, so that a Z axis is downward;
the overturning telescopic motor 8 extends to enable an output shaft of the overturning telescopic motor to be arranged in a corresponding moving groove 41 in a matching mode (the output shaft of the overturning motor 5 is in magnetic connection with the corresponding moving groove 41), the overturning telescopic motor 8 extends continuously to drive the MEMS-IMU sensor to move in the X-axis groove 21 (overturning components are arranged on two sides of the Y-axis groove 22), the output shaft of the overturning motor 5 is arranged in a corresponding overturning groove 40 in a matching mode, four leveling telescopic motors 3 are controlled to contract to provide a space for the overturning motor 5 to work to drive the MEMS-IMU sensor to continuously overturn for 90 degrees, the leveling telescopic motors 3 extend to receive the overturned MEMS-IMU sensor, the leveling telescopic motors 3 extend to drive the placing platform 2 to support the MEMS-IMU sensor, the overturning telescopic motors 8 contract to enable the output shaft of the overturning telescopic motors to be separated from the moving groove 41 under the resisting of the wall of the X-axis groove 21, controlling the four leveling telescopic motors 3 to level the placing platform 2 to realize that the Y axis faces downwards;
the four leveling telescopic motors 3 are contracted until the highest end of an output shaft is lower than the highest end of an output shaft connecting moving rod 10 of the rotating motor 1, the driving rod 10 of the rotating motor 1 is arranged in a driving groove 20 in a matching way, and the rotating motor 1 works to drive the placing platform 2 to rotate and adjust so that the Y-axis groove 22 and the overturning assembly are in relative positions, namely the overturning groove 40 and the moving groove 41 on the X-axis guide plate are in relative positions with the overturning assembly respectively;
four leveling telescopic motors 3 are controlled to level the placing platform 2, a pair of turning grooves 40 and moving grooves 41 along the Y axis are coaxially arranged with the output shaft of the worm 7 and the output shaft of the turning telescopic motor 8, the turning telescopic motor 8 extends to enable the output shaft of the turning telescopic motor to be matched and arranged in the corresponding moving groove 41 (the output shaft of the turning telescopic motor 8 is in magnetic connection with the corresponding moving groove 41), the turning telescopic motor 8 continues to extend to drive the MEMS-IMU sensor to move in the Y axis groove 22 (turning components are arranged on two sides of the X axis groove 21), the output shaft of the turning motor 5 is matched and arranged in the corresponding turning groove 40, the four leveling telescopic motors 3 are controlled to contract to provide a space for the turning motor 5 to work to drive the MEMS-IMU sensor to turn by 90 degrees, the leveling telescopic motors 3 extend to receive the MEMS-IMU sensor after turning, the leveling telescopic motors 3 extend to drive the placing platform 2 to support the MEMS-IMU sensor, the overturning telescopic motors 8 contract to enable output shafts of the overturning telescopic motors to be separated from the moving grooves 41 under the resisting of the groove walls of the Y-axis grooves 22, the four leveling telescopic motors 3 are controlled to enable the placing platform 2 to be leveled, and a pair of overturning grooves 40 and the moving grooves 41 are coaxially arranged with the output shafts of the worms 7 and the output shafts of the overturning telescopic motors 8, so that the X axis is upward;
the overturning telescopic motor 8 extends to enable an output shaft of the overturning telescopic motor to be arranged in a corresponding moving groove 41 in a matching mode (the output shaft of the overturning motor 5 is in magnetic connection with the corresponding moving groove 41), the overturning telescopic motor 8 continues to extend to drive the MEMS-IMU sensor to move in the Y-axis groove 22 (the overturning components are arranged on two sides of the X-axis groove 21), the output shaft of the overturning motor 5 is arranged in a corresponding overturning groove 40 in a matching mode, four leveling telescopic motors 3 are controlled to contract to provide a space for the overturning motor 5 to work to drive the MEMS-IMU sensor to overturn for 270 degrees, the leveling telescopic motors 3 extend to receive the overturned MEMS-IMU sensor, the leveling telescopic motors 3 extend to drive the placing platform 2 to support the MEMS-IMU sensor, and the overturning telescopic motor 8 contracts to enable the output shaft of the overturning telescopic motor to be separated from the moving groove 41 under the abutting of the wall of the Y-axis groove 22, and controlling the four leveling telescopic motors 3 to level the placing platform 2, so as to realize that the X axis faces downwards. By adopting the scheme, the rotary table unit is matched with the automatic control constant temperature unit to provide the required temperature environment for the MEMS-IMU sensor to be measured and correspondingly adjust the angle of 6 positions required by a hexahedron calibration method, and the MEMS-IMU sensor is directly positioned on the placing platform 2 when in the final measurement state and is not rigidly connected with an external transmission part, so that the leveling effect is improved; furthermore, a working heating component (a motor and the like) is not arranged in the incubator, the temperature control stability of the incubator is improved, and the service life loss of the temperature change of the incubator to the heating component is reduced.
While embodiments of the invention have been described above, it is not intended to be limited to the details shown, described and illustrated herein, but is to be accorded the widest scope consistent with the principles and novel features herein disclosed, and to such extent that such modifications are readily available to those skilled in the art, and it is not intended to be limited to the details shown and described herein without departing from the general concept as defined by the appended claims and their equivalents.

Claims (5)

1. The full-automatic calibration method for the MEMS-IMU sensor of the unmanned aerial vehicle is characterized by comprising the following steps:
s1, dividing the temperature range to be calibrated into two temperature ranges by taking the room temperature as a demarcation point;
s2, calibrating the MEMS-IMU sensor at room temperature, and obtaining calibration data at the calibration point at room temperature;
s3, determining a temperature interval for calibration, and calibrating the temperature interval, specifically:
s30, taking the current measured temperature as a temperature starting point and delta T as temperature change values of two adjacent measurements, determining the temperature after change, and judging whether the temperature after change exceeds the temperature interval;
s31, if yes, completing the calibration of the temperature interval;
s32, if not, the calibration data of the current calibration point is used for compensation and the data of the MEMS-IMU sensor under the changed temperature is calculated, and whether the compensated data is smaller than an error threshold value or not is judged;
s33, if yes, go to step S30;
if not, calibrating by taking the changed temperature as a new calibration point, obtaining calibration data at the temperature of the calibration point, and performing step S30;
the MEMS-IMU sensor comprises a three-axis gyroscope and a three-axis accelerometer, and the step S2 of calibrating the MEMS-IMU sensor specifically comprises the steps of calibrating the three-axis gyroscope and calibrating the three-axis accelerometer;
the calibration of the three-axis gyroscope specifically comprises the following steps:
keeping the MEMS-IMU sensor static at the temperature of the calibration point, continuously acquiring X-axis angular velocity data, Y-axis angular velocity data and Z-axis angular velocity data of the three-axis gyroscope for at least 100 times respectively, and then respectively obtaining X-axis zero offset, Y-axis zero offset and Z-axis zero offset of the gyroscope corresponding to the average value;
calibrating the three-axis gyroscope according to the X-axis zero offset, the Y-axis zero offset and the Z-axis zero offset, and forming calibration data of the three-axis gyroscope at the calibration point temperature;
the calibration of the triaxial accelerometer specifically comprises the following steps:
establishing an error model Accel of the triaxial accelerometer, wherein Accel is Maccel*Saccel*(Accelimu-Biasaccel) Wherein, M isaccelFor orthogonality errors of the three-axis accelerometer, SaccelIs the scale factor of a triaxial accelerometer, AccelimuFor the purpose of collecting triaxial accelerometer data, BiasaccelZero offset for a three-axis accelerometer;
continuously acquiring data of the triaxial accelerometer for at least 30 times at six positions respectively by adopting a hexahedral calibration method at the temperature of the calibration point, and then respectively calculating the average value to obtain Accel of the triaxial accelerometer at the six positionsimuData;
performing matrix calculation on the error model Accel and then ordering Paccel＝Saccel -1*Maccel -1Write as an augmented matrix, Accelimu＝[Paccel|Biasaccel]Accel, Accel based on data from the tri-axial accelerometer at six positionsimuObtaining PaccelLeast squares solution and zero-Bias ofaccel(ii) a Wherein the content of the first and second substances,
Figure FDA0003557661320000021
Figure FDA0003557661320000022
according to MaccelObtaining scale factor S of triaxial accelerometer with model-preserving propertyaccel；
According to Paccel＝Saccel -1*Maccel -1To obtain an orthogonality error Maccel；
According to a zero-BiasaccelA scale factor SaccelOrthogonality error MaccelAnd calibrating the triaxial accelerometer, and forming calibration data of the triaxial accelerometer at the temperature of the calibration point.
2. The method for fully automatically calibrating the unmanned aerial vehicle MEMS-IMU sensor according to claim 1, wherein in step S32, determining whether the compensated data is smaller than an error threshold, specifically including determining whether the compensated data of the tri-axial gyroscope is smaller than the error threshold and determining whether the compensated data of the tri-axial accelerometer is smaller than the error threshold, wherein the compensated data of the tri-axial gyroscope is a true angular velocity of three axes of the tri-axial gyroscope, and the compensated data of the tri-axial accelerometer is a component of the gravitational acceleration g in three axes.
3. The method for fully automatic calibration of unmanned aerial vehicle MEMS-IMU sensors according to claim 1, wherein Δ T-1 ℃.
4. The method for fully automatic calibration of MEMS-IMU sensors of unmanned aerial vehicles according to claim 2, wherein the error threshold of the tri-axial gyroscope data is 0.2 °/s and the error threshold of the tri-axial accelerometer data is 0.01 g.
5. The utility model provides a system of full-automatic calibration of unmanned aerial vehicle MEMS-IMU sensor which characterized in that includes:
the sensor data acquisition unit is connected with the MEMS-IMU sensor and is used for acquiring data of the MEMS-IMU sensor;
the control and data processing unit is connected with the sensor data acquisition unit through the data transmission unit, and the sensor data acquisition unit transmits acquired data to the control and data processing unit through the data transmission unit;
the rotary table unit is connected with the control and data processing unit and used for receiving and executing the angle instruction sent by the control and data processing unit, wherein the MEMS-IMU sensor is arranged on the rotary table unit;
the automatic control constant temperature unit is connected with the control and data processing unit and is used for receiving and executing the temperature instruction sent by the control and data processing unit, wherein the MEMS-IMU sensor is positioned in the temperature control range of the automatic control constant temperature unit;
the room temperature is used as a demarcation point, the temperature range to be calibrated is divided into two temperature intervals, and after a start instruction is received, the control and data processing unit control flow is set as follows:
sa, determining a temperature interval for calibration, calibrating the MEMS-IMU sensor at room temperature, and obtaining calibration data at a room temperature calibration point;
sb, taking the current measured temperature as a temperature starting point and delta T as temperature change values of two adjacent measurements, determining the temperature after change, and judging whether the temperature after change exceeds the temperature interval;
if the Sc is in the range, completing the calibration of the temperature range;
if not, sending an expected temperature to the automatic control constant temperature unit, determining that the MEMS-IMU sensor reaches the expected temperature, sending an expected angle to the turntable unit, determining that the MEMS-IMU sensor reaches the expected angle, compensating according to calibration data of a current calibration point, calculating data of the MEMS-IMU sensor at the changed temperature, and judging whether the compensated data is smaller than an error threshold value or not;
se, if so, performing the step Sb;
if not, calibrating by taking the changed temperature as a new calibration point, obtaining calibration data at the temperature of the calibration point, and performing the step Sb;
the automatic control constant temperature unit comprises a compressor unit and a temperature box connected with the compressor unit through a hose;
the turntable unit includes:
the platform assembly comprises a rotating motor, a placing platform and four leveling telescopic motors, wherein the rotating motor is arranged below the incubator, an output shaft of the rotating motor can rotatably penetrate through the bottom surface of the incubator, the placing platform is arranged in the incubator, the four leveling telescopic motors are arranged below the incubator, the output shaft of the leveling telescopic motors can movably penetrate through the bottom surface of the incubator, a driving groove with a non-cylindrical cross section is arranged in the center of the bottom surface of the placing platform, a driving rod matched with the driving groove is arranged at the top end of the rotating motor, the four leveling telescopic motors are arranged in a rectangular shape coaxially arranged with the placing platform along the circumferential direction, an X-axis groove and a Y-axis groove are formed in the top surface of the placing platform in a concave mode, and the X-axis groove and the Y-axis groove are crossed in an L shape;
the locking assembly comprises a pair of Y-axis guide plates respectively positioned at two ends of the placing platform along the X-axis direction, a pair of X-axis guide plates respectively positioned at two ends of the placing platform along the Y-axis direction, and Y-axis guide plates and X-axis guide plates which are adjacent along the circumferential direction are detachably and fixedly connected to form a space for fixedly containing the MEMS-IMU sensor, the side lengths of the Y-axis guide plates and the X-axis guide plates are equal, so that the Y-axis guide plates and the X-axis guide plates are fixedly connected to form a cube body, one of the Y-axis guide plates and one of the X-axis guide plates is sunken along the direction corresponding to the central axis and provided with a turnover groove with a non-circular end face, the other X-axis guide plate and the other Y-axis guide plate are sunken along the direction corresponding to the central axis and provided with a moving groove with a circular end face, and the bottom face of the moving groove is made of ferrous materials;
a turnover assembly which comprises a turnover motor positioned outside the incubator and close to one side of one turnover groove, a turbine fixedly arranged on an output shaft of the turnover motor, a worm meshed with the turbine, and a turnover telescopic motor positioned outside the incubator and arranged at the side opposite to the turnover motor, wherein the output shaft of the worm can rotatably penetrate through the incubator and is matched with the turnover groove, the output shaft of the turnover telescopic motor can rotatably penetrate through the incubator and is matched with the moving groove, the output shaft of the worm, the output shaft of the turning telescopic motor, the turning groove opposite to the output shaft of the worm and the moving groove opposite to the turning telescopic motor are coaxially arranged, the free end of the output shaft of the turning telescopic motor is made of magnetic materials, the magnetic connecting force between the output shaft of the turnover telescopic motor and the corresponding moving groove is smaller than the force for driving the MEMS-IMU sensor to turn over by the worm.
CN202010826434.2A 2020-08-17 2020-08-17 Method and system for full-automatic calibration of MEMS-IMU sensor of unmanned aerial vehicle Active CN112129320B (en)

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