Calibration method, calculation device and storage medium of inertial measurement unit

Abstract

The present invention provides a calibration method, computing device, and storage medium for an inertial measurement unit. The calibration method includes: sequentially placing the inertial measurement unit in at least three different postures for a predetermined period of time; calculating the Y-axis and Z-axis zero bias of the accelerometer based on at least three sets of acceleration measurements and a predetermined formula; calculating the gyroscope zero bias based on the angular velocity measurements of the gyroscope obtained in at least one posture; calculating the X-axis gyro integral angular increment based on the X-axis angular velocity measurements obtained from the first posture to the second posture; calculating the X-axis reference angular increment based on the acceleration measurements in the first posture and the second posture; and calculating the X-axis scale factor error of the gyroscope based on the X-axis gyro integral angular increment and the reference angular increment. This method only requires measurements in at least three different postures and does not require a high-precision turntable or horizontal marble platform to complete the calibration of the inertial measurement unit.

Description

Technical Field

[0001] The present invention relates to the field of inclinometers, and in particular to a calibration method, a computing device, and a storage medium for an inertial measurement unit. Background Art

[0002] Smart excavators require the precise position of the bucket tooth tip during construction to achieve accurate construction. Tooth tip positioning requires the installation of dynamic inclinometers on the excavator body, boom, dipper, and bucket to obtain real-time inclination information at the corresponding position. The measurement accuracy of the dynamic inclinometer depends on the performance of its core components: the accelerometer and gyroscope. As the dynamic inclinometer ages, the zero bias and scale factor of the accelerometer and gyroscope change to varying degrees, resulting in a decrease in dynamic inclinometer performance. In applications with high dynamic inclinometer performance requirements, such as smart excavator bucket tooth tip positioning, regular calibration of the accelerometer and gyroscope is required.

[0003] Currently, three-axis accelerometer bias calibration is typically performed using the six-position method. Calibration requires the use of a high-precision turntable or horizontal marble platform to rotate the accelerometer to at least six specific positions, with the ±X, ±Y, and ±Z axes of the accelerometer perpendicular to the horizontal plane. As an accelerometer ages, its bias typically changes to varying degrees, resulting in performance degradation. At this point, the accelerometer is often already installed in the customer's equipment, and removing it and returning it for recalibration is costly. Self-calibration using the aforementioned six-position method requires specialized equipment such as a turntable or horizontal marble platform, and may require disassembly and installation of the accelerometer, which is time-consuming and labor-intensive.

[0004] Therefore, it is necessary to propose an improved solution to overcome the related problems. Summary of the Invention

[0005] The present invention aims to provide a calibration method, a computing device, and a storage medium for an inertial measurement unit, which only require measurements of at least three different postures, do not require the user to remove the inertial measurement unit from the device, and do not require a high-precision turntable or a horizontal marble platform to complete the calibration of the acceleration zero bias and the scale factor of the gyroscope.

[0006] To achieve the purpose of the invention, according to one aspect of the present invention, a calibration method for an inertial measurement unit is provided, wherein the inertial measurement unit includes an accelerometer and a gyroscope, and the method comprises: sequentially placing the inertial measurement unit in at least three different postures within a plane defined by a Z axis and a Y axis for a predetermined period of time, obtaining a set of acceleration measurement values ​​output by the three-axis accelerometer in each posture, obtaining an angular velocity measurement value output by the gyroscope in at least one posture, and obtaining an angular velocity measurement value of the X axis of the gyroscope during the movement of the inertial measurement unit from a first posture to a second posture, wherein each set of acceleration measurement values ​​includes acceleration measurement values ​​of three axes, and the first posture and the second posture are each one of the at least three different postures; and solving the zero bias by,b of the Y axis and the Z axis of the accelerometer based on the obtained at least three sets of acceleration measurement values ​​and a predetermined formula. z The predetermined formula is constructed based on the modulus of the true value of the three-axis acceleration being the local gravity acceleration; the zero bias of the gyroscope is calculated based on the angular velocity measurement value of the gyroscope obtained in the at least one posture; and the gyroscope integrated angle increment of the X-axis of the gyroscope during the movement from the first posture to the second posture is calculated based on the angular velocity measurement value of the X-axis of the gyroscope obtained during the movement of the inertial measurement unit from the first posture to the second posture; the first roll angle of the inertial measurement unit in the first posture is calculated based on a set of acceleration measurement values ​​in the first posture; the second roll angle of the inertial measurement unit in the second posture is calculated based on a set of acceleration measurement values ​​in the second posture; the reference angle increment of the X-axis of the gyroscope from the first posture to the second posture is calculated based on the first roll angle of the inertial measurement unit in the first posture and the second roll angle of the inertial measurement unit in the second posture; and the scale factor error of the X-axis of the gyroscope is calculated based on the gyroscope integrated angle increment and the reference angle increment of the X-axis of the gyroscope during the movement from the first posture to the second posture.

[0007] In one aspect, the predetermined formula is:

[0008]

[0009] Substitute the obtained at least three sets of acceleration measurement values ​​into the predetermined formula to solve the zero bias b of the Y axis and the Z axis. y ,b z , where y i ,z i are the acceleration measurement values ​​of the Y axis and Z axis of the three-axis accelerometer, r is the local gravity acceleration, and i is the sequence number of at least three different postures.

[0010] According to another aspect of the present invention, the present invention provides a computing device, comprising a processor and a memory, wherein the memory stores program instructions, and the program instructions are executed by the processor to implement the above-mentioned zero bias calibration method of the three-axis accelerometer.

[0011] According to yet another aspect of the present invention, the present invention provides a storage medium storing program instructions, wherein the program instructions are executed to implement the above-mentioned zero bias calibration method of the three-axis accelerometer.

[0012] Compared to the prior art, the present invention constructs a predetermined formula for the local gravitational acceleration based on the modulus of the true values ​​of the three-axis accelerations, and solves for the two-axis bias based on this predetermined formula. This allows the present invention to complete accelerometer bias calibration by requiring only measurements in at least three different postures and without the need for a high-precision turntable or horizontal marble platform. Furthermore, by using the accelerometer to calculate the reference angle increment of the gyroscope's X-axis during movement from a first posture to a second posture, the present invention can calibrate the gyroscope's X-axis scale factor error. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a flow chart of a calibration method of an inertial measurement unit in the present invention;

[0014] Figure 2 Schematic diagrams of four postures of an excavator equipped with an inertial measurement unit according to the present invention;

[0015] Figure 3 A schematic diagram of a case where the excavator is tilted and the accelerometer has an installation error in the present invention;

[0016] Figure 4 Schematic diagram of the reading distribution of the three-axis accelerometer in four postures in three different views. DETAILED DESCRIPTION

[0017] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0018] This solution proposes a calibration method for an inertial measurement unit. The dynamic tilt angle includes an accelerometer and a gyroscope. By simply controlling the inertial measurement unit to rotate to at least three different postures, the 2-axis zero bias calibration of the accelerometer and the calibration of the X-axis scale factor error of the gyroscope can be achieved. There is no need for equipment such as a high-precision turntable or a horizontal marble platform, nor is there any need to rotate the accelerometer to specific six different postures for calibration.

[0019] Figure 1This is a flow chart of a calibration method 100 of an inertial measurement unit in the present invention. The calibration method 100 can realize the zero bias calibration of the two axes of the three-axis accelerometer and the calibration of the X-axis scale factor error of the gyroscope. The calibration method in the present invention is explained below by taking the installation of the inertial measurement unit on the excavator 210 as an example. However, it is obvious that the inertial measurement unit can also be installed on other vehicles or equipment, and the calibration method in the present invention can also be used in these applications. In a typical application, the inertial measurement unit is implemented as a dynamic inclinometer, which can be installed on the body, boom, arm and bucket of the intelligent excavator to obtain real-time inclination information of the corresponding position, wherein the dynamic inclinometers on the boom, arm and bucket other than the body can apply the calibration method in the present invention. The inertial measurement unit includes a three-axis accelerometer and a gyroscope.

[0020] like Figure 1 As shown, the calibration method 100 includes the following steps.

[0021] Step 110: sequentially placing the inertial measurement unit in at least three different postures within a plane defined by the Z axis and the Y axis for a predetermined period of time, obtaining a set of acceleration measurement values ​​output by the three-axis accelerometer in each posture, obtaining an angular velocity measurement value output by the gyroscope in at least one posture, and obtaining an angular velocity measurement value of the X axis of the gyroscope during the movement of the inertial measurement unit from the first posture to the second posture, wherein each set of acceleration measurement values ​​includes acceleration measurement values ​​of three axes, and the first posture and the second posture are each one of the at least three different postures.

[0022] Specifically, the inertial measurement unit is installed on the boom, arm or bucket of the excavator, and the excavator controls the boom, arm or bucket to sequentially place the inertial measurement unit in at least three different postures within the plane defined by the Z axis and the Y axis. The accelerometer and gyroscope in the inertial measurement unit are integrated together, for example, they are set in the same unit, so the postures of the accelerometer and the gyroscope are consistent, and the directions of the X, Y, and Z axes of the accelerometer and the X, Y, and Z axes of the gyroscope are consistent. Figure 2As shown, four different postures are shown here, namely P1, P2, P3 and P4. The predetermined time length can be greater than 3 seconds, such as 4, 5, 7 seconds, etc., and the average acceleration of each axis of the three-axis accelerometer during the static period is used as the acceleration measurement value of the axis, which can eliminate some measurement errors. In the four postures, the X-axis always remains roughly horizontal, that is, parallel to the ground, so the difference in the acceleration measurement value of the X-axis in each group of acceleration measurement values ​​is very small, for example, it will be less than a predetermined threshold, so the zero bias of the X-axis of the accelerometer cannot be calibrated, and only the zero bias of the Z-axis and Y-axis of the accelerometer can be calibrated. Of course, it is also possible to only collect three groups of acceleration measurement values ​​under three postures for subsequent zero bias calibration of the accelerometer. In addition, even if the X-axis is not set horizontally, the X-axis can be made horizontal by tilt calibration later.

[0023] In one embodiment, the maximum angle difference between the Y axis and the gravity line in each posture is greater than a first predetermined angle threshold, and the maximum angle difference between the Z axis and the gravity line in each posture is greater than a second predetermined angle threshold. Figure 2 As shown in the figure, the angle between the Y axis and the gravity line is the smallest in the P1 posture, and the angle between the Y axis and the gravity line is the largest in the P2 posture. Therefore, the angle difference between the angle between the Y axis and the gravity line in the P1 posture and the angle between the Y axis and the gravity line in the P2 posture is the maximum angle difference, and this maximum angle difference is about more than 180 degrees. Similarly, Figure 2 As shown, the angle between the Z axis and the gravity line is the smallest in the P1 posture, and the angle between the Z axis and the gravity line is the largest in the P2 posture. Therefore, the angle difference between the angle between the Z axis and the gravity line in the P1 posture and the angle between the Z axis and the gravity line in the P2 posture is the maximum angle difference, and this maximum angle difference is approximately more than 180 degrees. When the maximum angle difference is relatively large, the subsequent calibration effect will be more accurate. For smaller maximum angle differences, the calibration method of the present invention is also applicable. In one embodiment, the first predetermined angle threshold and the second predetermined angle threshold are both greater than or equal to 30 degrees.

[0024] It should be noted that, in the present invention, the plane in which the excavator's boom 220 can move is defined as the plane of the Y-axis and the Z-axis, and the direction perpendicular to the plane of movement is defined as the X-axis. The X-axis, Y-axis, and Z-axis are already defined when the accelerometer is installed. In other descriptions, other definitions may also be used.

[0025] Specifically, such as Figure 2As shown, the inertial measurement unit can be placed in posture P1 for 5 seconds, then moved from posture P1 to posture P2, and then placed in posture P2 for 5 seconds. Then, it can be moved from posture P2 to posture P3, and then placed in posture P3 for 5 seconds. Then, it can be moved from posture P3 to posture P4, and then placed in posture P4 for 5 seconds. In each posture, the accelerometer and the gyroscope can sample to obtain acceleration measurement values ​​and angular velocity measurement values. During the process of moving from one posture to another, the gyroscope can also sample to obtain angular velocity measurement values. The first posture can be posture P1, P2, or P3, and the second posture can be posture P2, P3, or P4.

[0026] Step 120: Calculate the zero bias b of the Y axis and the Z axis based on the obtained at least three sets of acceleration measurement values ​​and a predetermined formula. y ,b z The predetermined formula is constructed based on the modulus of the true value of the three-axis acceleration as the local gravity acceleration.

[0027] In one embodiment, the predetermined formula is:

[0028]

[0029] Substitute the obtained at least three sets of acceleration measurement values ​​into the predetermined formula to solve the zero bias b of the Y axis and the Z axis. y ,b z , where y i ,z i where y and z are the acceleration measurements of the three-axis accelerometer, r is the local acceleration due to gravity, and i is the index of at least three different postures. The x-axis is usually parallel to the ground plane. Even if it is not parallel, it needs to be compensated to make it parallel to the ground.

[0030] The following describes the derivation process of the above predetermined formula.

[0031] The measurement model of the accelerometer is:

[0032]

[0033] in: is the accelerometer measurement value, f is the accelerometer true value, b f is the zero bias of the accelerometer, and s is the scale factor error of the accelerometer.

[0034] According to actual engineering experience, the scale factor error of the accelerometer is generally small, so we simplify formula (1) to obtain:

[0035]

[0036] Let: xi ,y i ,z i is the measurement value of the triaxial accelerometer, b x ,b y ,b z is the zero bias of each axis of the three-axis accelerometer, and r is the local gravity acceleration. According to the modulus of the true value of the three-axis acceleration as the local gravity acceleration, the equation is constructed:

[0037] (x i -b x ) 2 +(y i -b y ) 2 +(z i -b z ) 2 =r 2 (3)

[0038] Equation (3) shows that the zero bias calibration of a three-axis accelerometer is essentially a problem of solving the sphere center and radius based on sphere fitting. That is, given the coordinates of at least three points on the surface of a spatial sphere, the coordinates of the circle center and the length of the radius are solved. Therefore, the more dispersed the distribution of multiple points on the sphere, the more accurate the sphere fitting result. In special cases, when the distribution of multiple points approximates a circle, Equation (3) degenerates into the equation of a plane circle. For example, in the calibration example of a three-axis accelerometer in an excavator, the X-axis data of the accelerometer's multiple postures are very different, so the equation must be solved based on circle fitting.

[0039] Expanding and reorganizing formula (3) yields:

[0040]

[0041] For simplicity, formula (4) can be organized as:

[0042]

[0043] in:

[0044] When there are four sets of accelerometer measurements, equation (5) can be written in matrix form:

[0045]

[0046] Use Gaussian elimination method to solve equation (6) and obtain the unknowns A, B, C, and D, and then calculate the 3-axis accelerometer zero bias and local gravity acceleration as follows:

[0047]

[0048] In the application example where the triaxial accelerometer is installed on an excavator, the measured value of the X-axis varies little under various postures, so the zero bias of the X-axis cannot be obtained. Therefore, it is only necessary to set the terms related to the X-axis in formula (4) to 0. In this way, formula (4) can be simplified to the predetermined formula:

[0049]

[0050] At this point, at least three sets of acceleration measurements under three postures are needed to obtain the accelerometer zero bias b. y ,b z .

[0051] In practice, taking the excavator application as an example, when the uneven road surface causes the excavator body to tilt and the accelerometer has installation errors, such as Figure 3 As shown in the figure, the X-axis of the triaxial accelerometer has significant numerical differences in several postures, resulting in significant errors when using circular fitting to solve the accelerometer zero bias.

[0052] like Figure 4 As shown, the distribution diagram of the three-axis readings of the accelerometer under four postures is displayed in three different views (a, b and c), where L1 is the distribution of the three-axis readings of the accelerometer when the vehicle body tilt angle is 0 degrees, and L2 is the distribution of the three-axis readings of the accelerometer when the vehicle body tilt angle is 10 degrees.

[0053] like Figure 3 As shown, the gravity line forms an inclination angle with the plane defined by the Z axis and the Y axis, and the accelerometer is in a tilted state.

[0054] The calibration method 100 further includes:

[0055] Calculating attitude angles in at least three different attitudes based on at least three sets of acceleration measurements;

[0056] Calculate the tilt attitude matrix R under at least three different attitudes of the tilt state according to the attitude angles under at least three different attitudes obtained tilt_i And the normal posture matrix R under at least three different postures of the normal state ⊥_i , and then get the tilt posture matrix R tilt_i To the normal posture matrix R ⊥_i The rotation matrix

[0057] Using the rotation matrix Compensate each set of acceleration measurement values ​​output by the three-axis accelerometer, and substitute each set of compensated acceleration measurement values ​​into the predetermined formula to solve the zero bias of the Y axis and Z axis of the accelerometer by,b z .

[0058] Wherein, the attitude angle is [Yaw i ,Pitch i ,Roll i ], Yaw is the yaw angle, Pitch is the pitch angle, Roll is the roll angle, and Pitch is the attitude angle in at least three different attitudes in the tilt state i is the tilt angle, the Pitch angle in at least three different postures in the normal state i is 0, Yaw i Both are 0.

[0059] Compensated acceleration measurement value for:

[0060]

[0061] in is the acceleration measurement value before compensation.

[0062] After obtaining the accelerometer bias, the accelerometer bias compensation can be performed, that is, the acceleration bias is removed from the accelerometer measurement value. According to the above formula (2), the compensated accelerometer true value f is:

[0063]

[0064] Among them, b f is the zero bias of the accelerometer, and the zero bias of its three axes are b x ,b y and b z . Each time the acceleration measurement value of the accelerometer is collected After that, the accelerometer zero bias compensation can be performed in real time according to the above formula.

[0065] This allows for two-axis zero-bias calibration of the accelerometer within the IMU without disassembling the unit. This is simple and quick, and doesn't require a high-precision turntable or level marble platform; calibration can be performed on a standard surface, such as a desktop. Furthermore, zero-bias calibration of the accelerometer along all three axes can be performed using at least attitude data.

[0066] Step 130: Calculate the zero bias of the gyroscope according to the angular velocity measurement value of the gyroscope obtained during the at least one posture.

[0067] In one embodiment, the measurement model of the gyroscope is:

[0068]

[0069] in: is the angular velocity measurement value of the gyroscope, ω is the true value of the gyroscope, bω is the gyroscope zero bias, s: gyroscope scale factor error.

[0070] When the gyroscope is stationary, ω is 0. According to formula (7), the angular increment in the time period [T1, T2] can be obtained as:

[0071]

[0072] Where Δt is the data sampling interval of the gyroscope, and n is the number of sampling points in the time period [T1, T2], that is, the number of angular velocity measurements, from which the zero bias b of the gyroscope can be estimated under static conditions. ω for:

[0073]

[0074] In one embodiment, b ω It can be obtained by measuring the angular velocity of the gyroscope when the inertial measurement unit is stationary in posture P1. The gyroscope includes three axes, X, Y and Z axes. Usually, the same principle can be used to obtain the zero bias b of the X, Y and Z axes respectively. ωx , b ωy and b ωz Of course, it is also possible to calculate the zero offset of only one or two of the three axes.

[0075] Step 140: Calculate a gyro-integrated angle increment of the X-axis of the gyroscope during the movement from the first posture to the second posture based on the angular velocity measurement value of the X-axis of the gyroscope obtained during the movement of the inertial measurement unit from the first posture to the second posture; calculate a first roll angle of the inertial measurement unit at the first posture based on a set of acceleration measurement values ​​at the first posture; calculate a second roll angle of the inertial measurement unit at the second posture based on a set of acceleration measurement values ​​at the second posture; calculate a reference angle increment of the X-axis of the gyroscope during the movement from the first posture to the second posture based on the first roll angle of the inertial measurement unit at the first posture and the second roll angle of the inertial measurement unit at the second posture; and calculate a scale factor error of the X-axis of the gyroscope based on the gyro-integrated angle increment of the X-axis of the gyroscope and the reference angle increment during the movement from the first posture to the second posture.

[0076] In one embodiment, the first roll angle roll1 of the inertial measurement unit in the first posture is:

[0077]

[0078] in, and are the acceleration measurement values ​​of the Y and Z axes of the accelerometer in the first posture respectively; b y with bz are the zero biases of the Y and Z axes of the accelerometer, respectively, which have been determined in step 120 .

[0079] Similarly, the second roll angle roll2 of the inertial measurement unit in the second posture is:

[0080]

[0081] in, and are the acceleration measurement values ​​of the Y and Z axes of the accelerometer in the second posture respectively.

[0082] The reference angle increment θ of the X-axis of the gyroscope during the movement from the first posture to the second posture is:

[0083] θ=roll2-roll1.

[0084] The gyro integral angle increment of the X-axis of the gyroscope during the movement from the first posture to the second posture is obtained according to the integral of the angular velocity of the gyroscope. It is:

[0085]

[0086] Where Δt is the data sampling interval of the gyroscope, b ωx is the zero bias of the X axis of the gyroscope, is the angular velocity measurement value of the X-axis of the gyroscope during the movement from the first posture to the second posture, m is the number of angular velocity measurement values ​​of the X-axis of the gyroscope during the movement from the first posture to the second posture, that is, the number of samples, and j is the sampling sequence number.

[0087] The scale factor error of the gyroscope on the X axis is s x for:

[0088]

[0089] Will Substituting θ into formula (9) yields:

[0090]

[0091] In this way, the S scale factor error s of the X-axis of the gyroscope can be obtained x .

[0092] After that, the scale factor error of the gyroscope can be compensated, that is, the influence of the scale factor error can be removed from the angular velocity measurement value of the gyroscope. According to the above formula (7), the true value of the angular velocity of the X axis of the gyroscope after compensation ω can be obtained. x for:

[0093]

[0094] Among them, b ω and s x Already obtained above.

[0095] Each time the gyroscope acceleration measurement value is collected After that, the X-axis scale factor error compensation can be performed in real time according to the above formula.

[0096] The present invention has the following advantages: only at least three postures are needed to calibrate the accelerometer bias and the gyroscope scale factor, which is simpler than the traditional six-posture calibration; there is no need to remove the inertial measurement unit from the equipment, saving time and effort; and calibration does not require the use of equipment such as a high-precision turntable or a horizontal marble platform, reducing the difficulty of calibration.

[0097] The IMU (Inertial Measurement Unit) mentioned in this invention is one of the core hardware of the dynamic inclinometer. The main sensors in the IMU are accelerometers and gyroscopes. Therefore, the calibration of the accelerometer zero bias and gyroscope scale factor involved in this invention is not only applicable to dynamic inclinometers, but also to other IMUs and other devices based on IMUs.

[0098] According to another aspect of the present invention, the present invention provides a computing device, comprising a processor and a memory, wherein the memory stores program instructions, and the program instructions are executed by the processor to implement the above-mentioned zero bias calibration method of the three-axis accelerometer.

[0099] According to yet another aspect of the present invention, the present invention provides a storage medium storing program instructions, wherein the program instructions are executed to implement the above-mentioned zero bias calibration method of the three-axis accelerometer.

[0100] As used herein, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion of elements other than the listed elements and may also include additional elements not specifically listed.

[0101] In this document, directional terms such as front, back, top, and bottom are defined based on the positions of components in the accompanying drawings and relative to each other, and are intended only for clarity and convenience in describing the technical solution. It should be understood that the use of these directional terms should not limit the scope of protection claimed in this application.

[0102] In the absence of conflict, the above embodiments and features in the embodiments may be combined with each other.

[0103] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for calibrating an inertial measurement unit, wherein the inertial measurement unit includes an accelerometer and a gyroscope, characterized in that: It includes: sequentially placing the inertial measurement unit in at least three different postures within a plane defined by a Z axis and a Y axis for a predetermined period of time, obtaining a set of acceleration measurements output by a three-axis accelerometer in each posture, obtaining an angular velocity measurement output by the gyroscope in at least one posture, and obtaining an angular velocity measurement of the gyroscope along an X axis as the inertial measurement unit moves from a first posture to a second posture, wherein each set of acceleration measurements includes acceleration measurements along the three axes, and the first posture and the second posture are each one of the at least three different postures; The zero bias b of the Y-axis and Z-axis of the accelerometer is solved according to the obtained at least three groups of acceleration measurement values ​​and a predetermined formula. y ,b z , the predetermined formula is constructed based on the modulus of the true value of the three-axis acceleration as the local gravity acceleration; The zero bias of the gyroscope is calculated based on the angular velocity measurement values ​​of the gyroscope obtained in the at least one posture; the gyroscope integrated angle increment of the X-axis of the gyroscope during the movement from the first posture to the second posture is calculated based on the angular velocity measurement values ​​of the X-axis of the gyroscope obtained during the movement of the inertial measurement unit from the first posture to the second posture; the first roll angle of the inertial measurement unit in the first posture is calculated based on a group of acceleration measurement values ​​in the first posture; the second roll angle of the inertial measurement unit in the second posture is calculated based on a group of acceleration measurement values ​​in the second posture; the reference angle increment of the X-axis of the gyroscope during the movement from the first posture to the second posture is calculated based on the first roll angle of the inertial measurement unit in the first posture and the second roll angle of the inertial measurement unit in the second posture; and the scale factor error of the X-axis of the gyroscope is calculated based on the gyroscope integrated angle increment and the reference angle increment of the X-axis of the gyroscope during the movement from the first posture to the second posture.

2. The calibration method according to claim 1, wherein: The predetermined formula is: Substitute the obtained at least three sets of acceleration measurement values ​​into the predetermined formula to solve the zero bias b of the Y axis and the Z axis. y ,b z , where y i ,z i are the acceleration measurement values ​​of the Y axis and Z axis of the three-axis accelerometer, r is the local gravity acceleration, and i is the sequence number of at least three different postures.

3. The calibration method according to claim 2, wherein: The difference in the acceleration measurement values ​​of the X-axis in each group of acceleration measurement values ​​is less than a predetermined threshold, the maximum angular difference between the angles between the Y-axis and the gravity line in at least three different postures is greater than a first predetermined angular threshold, the maximum angular difference between the angles between the Z-axis and the gravity line in at least three different postures is greater than a second predetermined angular threshold, and the X-axis is parallel to the ground.

4. The calibration method according to claim 3, wherein: The gravity line forms an inclination angle with the plane defined by the Z axis and the Y axis, and the accelerometer is in a tilted state. It also includes: Calculating attitude angles at at least three different attitudes based on at least three sets of acceleration measurements; Calculate the tilt attitude matrix R of at least three different attitudes in the tilt state according to the attitude angles of at least three different attitudes obtained tilt_i And the normal posture matrix R for at least three different postures in the normal state ⊥_i , and then get the tilt posture matrix R tilt_i To the normal posture matrix R ⊥_i The rotation matrix Using the rotation matrix Compensate each set of acceleration measurement values ​​output by the three-axis accelerometer, and substitute each set of compensated acceleration measurement values ​​into the predetermined formula to solve the zero bias b of the Y axis and the Z axis. y ,b z .

5. The calibration method according to claim 4, characterized in that: The attitude angle is [Yaw i ,Pitch i ,Roll i ], Yaw is the yaw angle, Pitch is the pitch angle, Roll is the roll angle, and Pitch is the attitude angle of at least three different attitudes in the tilt state i is the tilt angle, the pitch angle in at least three different postures in the normal state i is 0, Yaw i All are 0, Compensated acceleration measurement value for: in is the acceleration measurement value before compensation.

6. The calibration method according to claim 1, wherein: The inertial measurement unit is mounted on the boom, arm or bucket of the excavator, and the excavator controls the boom, arm or bucket so that the inertial measurement unit is sequentially placed in at least three different postures within the plane defined by the Z axis and the Y axis. The predetermined time period is greater than 3 seconds, and the average acceleration value of each axis of the accelerometer during the static period is used as the acceleration measurement value of each axis.

7. The calibration method according to claim 1, wherein: The first roll angle roll1 of the inertial measurement unit in the first posture is: in, and are the acceleration measurement values ​​of the Y and Z axes of the accelerometer in the first posture respectively; b y with b z are the zero bias of the Y and Z axes of the accelerometer respectively; The second roll angle roll2 of the inertial measurement unit in the second posture is: in, and are the acceleration measurement values ​​of the Y and Z axes of the accelerometer in the second posture, The reference angle increment θ of the X-axis of the gyroscope during the movement from the first posture to the second posture is: θ=roll2-roll1.

8. The calibration method according to claim 7, characterized in that: The gyro integrated angle increment of the X-axis of the gyroscope during the movement from the first posture to the second posture for Where Δt is the data sampling interval of the gyroscope, b ωx is the zero bias of the X axis of the gyroscope, is the angular velocity measurement value of the X-axis of the gyroscope during the movement from the first posture to the second posture, m is the number of angular velocity measurement values ​​of the X-axis of the gyroscope during the movement from the first posture to the second posture, that is, the number of samples, The scale factor error of the gyroscope on the X axis is s x for:

9. The calibration method according to claim 8, characterized in that: The gyroscope's zero bias b ω for: in is the angular velocity measurement value of the gyroscope, n is the number of samples of the gyroscope, and the zero bias b of the X axis of the gyroscope is obtained. ωx .

10. A computing device comprising a processor and a memory, wherein the memory stores program instructions, and the program instructions are executed by the processor to implement the calibration method of the inertial measurement unit according to any one of claims 1 to 9.

11. A storage medium storing program instructions, wherein the program instructions are executed to implement the calibration method of an inertial measurement unit according to any one of claims 1 to 9.

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