Installation angle calibration method, vehicle-mounted device and storage medium

Abstract

The invention relates to the field of intelligent driving, and provides an installation angle calibration method, a vehicle-mounted device and a storage medium, and the method comprises the steps: defining a first coordinate system corresponding to an IMU according to first IMU data obtained from the IMU of a vehicle, and determining a first rotation angle of the first coordinate system relative to a second coordinate system where the vehicle is located; updating the first coordinate system based on the first rotation angle to obtain a third coordinate system corresponding to the IMU; acquiring second IMU data of the vehicle, and extracting target peak data from the second IMU data; determining a second rotation angle of the third coordinate system relative to the second coordinate system based on the target peak data; and determining an installation angle of the IMU relative to the vehicle based on the first rotation angle and the second rotation angle. By using the method, the cost and difficulty of IMU calibration can be reduced, and the efficiency of IMU calibration can be improved.

Description

Technical Field

[0001] The present application belongs to the field of intelligent driving and relates to coordinate system calibration technology, and specifically to an installation angle calibration method, a vehicle-mounted device and a storage medium. Background Art

[0002] Inertial measurement unit (IMU) is a common sensor used to obtain vehicle posture information. The IMU data can be used to analyze the vehicle's posture and displacement information to assist in vehicle control and navigation. Since IMU data will be affected by the installation angle, it is necessary to calibrate the IMU's installation angle when using the IMU to analyze the vehicle. The IMU installation angle calibration method in the related art requires the use of other sensors or complex filter models, or requires the initial value of the IMU's installation angle to be determined in advance before error calibration. It also needs to be implemented in a complex application environment. For example, it is necessary to use an extra-long straight runway to allow the vehicle to reach a higher speed or acceleration for error calibration. Therefore, the calculation cost is high and the calculation efficiency is low. Summary of the invention

[0003] In view of the above, it is necessary to propose an installation angle calibration method, a vehicle-mounted device and a storage medium, which can solve the problems of high calculation cost and low calculation efficiency of related installation angle calibration methods.

[0004] An embodiment of the present application provides an installation angle calibration method, which includes: defining a first coordinate system corresponding to an inertial measurement unit (IMU) of a vehicle based on first IMU data obtained from the IMU, and determining a first rotation angle of the first coordinate system relative to a second coordinate system in which the vehicle is located; updating the first coordinate system based on the first rotation angle to obtain a third coordinate system corresponding to the IMU; obtaining second IMU data of the vehicle, and extracting target peak data from the second IMU data; determining a second rotation angle of the third coordinate system relative to the second coordinate system based on the target peak data; and determining an installation angle of the IMU relative to the vehicle based on the first rotation angle and the second rotation angle.

[0005] In one embodiment, the first coordinate system corresponding to the inertial measurement unit IMU of the vehicle is defined based on first IMU data obtained from the IMU, including: obtaining the IMU data of the vehicle when it is stationary as the first IMU data; determining the maximum value of three original accelerations in the three original coordinate axis directions corresponding to the original coordinate system of the IMU based on the first IMU data, and taking the original coordinate axis corresponding to the maximum value as the target coordinate axis; defining the first vertical axis of the first coordinate system based on the target coordinate axis, and determining the first horizontal axis and the first vertical axis of the first coordinate system based on the first vertical axis.

[0006] In one embodiment, the second vertical axis of the second coordinate system is in the same direction as the direction of gravity acceleration; determining the first rotation angle of the first coordinate system compared to the second coordinate system where the vehicle is located includes: determining the first acceleration in the first horizontal axis direction of the first coordinate system and the second acceleration in the first vertical axis direction of the first coordinate system according to the first IMU data; determining the first angle between the first horizontal axis of the first coordinate system and the second horizontal axis of the second coordinate system based on the inverse sine function of the ratio of gravity acceleration to the first acceleration; determining the second angle between the first vertical axis of the first coordinate system and the second vertical axis of the second coordinate system based on the inverse sine function of the ratio of gravity acceleration to the second acceleration; and using the first angle and the second angle as the first rotation angle between the first coordinate system and the second coordinate system.

[0007] In one embodiment, the first coordinate system is updated based on the first rotation angle to obtain a third coordinate system corresponding to the IMU, including: constructing a rotation matrix based on the first rotation angle, rotating the first horizontal axis and the first vertical axis of the first coordinate system according to the rotation matrix to obtain the third coordinate system, and the third vertical axis of the third coordinate system is parallel to the second vertical axis of the second coordinate system.

[0008] In one embodiment, the acquiring of the second IMU data of the vehicle and the extracting of the target peak data from the second IMU data include: acquiring the IMU data of the vehicle when turning as the second IMU data; determining from the second IMU data an angular velocity peak value in the third vertical axis direction of the third coordinate system that is greater than a preset threshold and a peak time node corresponding to the angular velocity peak value; extracting from the second IMU data a third acceleration in the third horizontal axis direction and a fourth acceleration in the third longitudinal axis direction of the third coordinate system corresponding to the peak time node, and using the third acceleration and the fourth acceleration as the target peak data.

[0009] In one embodiment, determining the second rotation angle of the third coordinate system relative to the second coordinate system based on the target peak data includes: determining the angle between the third horizontal axis of the third coordinate system and the direction of the centripetal force exerted on the vehicle when the second IMU data is obtained based on the inverse tangent function of the ratio of the fourth acceleration to the third acceleration; determining the second rotation angle according to the angle and the turning direction of the vehicle when the second IMU data is obtained.

[0010] In one embodiment, determining the second rotation angle based on the included angle and the turning direction of the vehicle when acquiring the second IMU data includes: when the turning direction of the vehicle is a right turn, determining the second rotation angle based on the difference between the included angle and a right angle; when the turning direction of the vehicle is a left turn, determining the second rotation angle based on the sum of the included angle and the right angle.

[0011] In one embodiment, the method further includes: performing data optimization processing on multiple angles determined based on multiple second IMU data, and determining the second rotation angle based on the optimal angle obtained after the data optimization processing.

[0012] An embodiment of the present application provides an installation angle calibration device, which includes: a determination module, which is used to define a first coordinate system corresponding to an inertial measurement unit (IMU) of a vehicle based on first IMU data obtained from the IMU, and determine a first rotation angle of the first coordinate system compared to a second coordinate system where the vehicle is located; an update module, which is used to update the first coordinate system based on the first rotation angle to obtain a third coordinate system corresponding to the IMU; an extraction module, which is used to obtain second IMU data of the vehicle and extract target peak data from the second IMU data; the determination module is also used to determine a second rotation angle of the third coordinate system compared to the second coordinate system based on the target peak data; the determination module is also used to determine the installation angle of the IMU compared to the vehicle based on the first rotation angle and the second rotation angle.

[0013] An embodiment of the present application provides a vehicle-mounted device, which includes: a memory and at least one processor, and the processor is used to implement the installation angle calibration method when executing a computer program stored in the memory.

[0014] An embodiment of the present application provides a vehicle, which includes at least one inertial measurement unit and the vehicle-mounted device.

[0015] An embodiment of the present application provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the installation angle calibration method is implemented.

[0016] To sum up, the installation angle calibration method described in the present application does not require the installation of other sensors or the use of complex models, and does not require the use of complex application environments. By calibrating the installation angle of the IMU according to the IMU data of the vehicle in different states, the installation angle of the IMU installed at any angle at any position of the vehicle can be calibrated in real time, thereby reducing the cost and difficulty of IMU calibration and improving the efficiency of IMU calibration. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural diagram of a vehicle-mounted device provided in one embodiment of the present application.

[0018] Figure 2 This is an example diagram of the installation position of an inertial measurement unit in a vehicle provided by an embodiment of the present application.

[0019] Figure 3 It is a flow chart of an installation angle calibration method provided in one embodiment of the present application.

[0020] Figure 4 This is an example diagram of the original coordinate system of the inertial measurement unit provided in one embodiment of the present application.

[0021] Figure 5 This is an example diagram of the horizontal operation of the installation angle of the IMU in the vehicle provided by one embodiment of the present application.

[0022] Figure 6 This is an example diagram of the rotation direction of a positive value of the installation angle provided by an embodiment of the present application.

[0023] Figure 7 This is an example diagram of the third coordinate system of the installation angle provided in one embodiment of the present application.

[0024] Figure 8 This is an example diagram of the second IMU data provided by an embodiment of the present application.

[0025] Fig. 9 This is an example diagram of the centripetal force applied to a vehicle while traveling on a curve, provided by one embodiment of the present application.

[0026] Fig.10 This is an example diagram of the coordinate system of the IMU aligned with the vehicle coordinate system provided in one embodiment of the present application.

[0027] Fig.11 It is a structural diagram of an installation angle calibration device provided in one embodiment of the present application. DETAILED DESCRIPTION

[0028] In order to more clearly understand the above-mentioned purposes, features and advantages of the present application, the present application is described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing the embodiments in one embodiment and are not intended to limit this application.

[0030] It should be noted that in this application, "at least one" means one or more, and "more than one" means two or more than two. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural. The terms "first", "second", "third", "fourth", etc. (if any) in the specification, claims and drawings of this application are used to distinguish similar objects, rather than to describe a specific order or sequence.

[0031] In the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a concrete way. The following embodiments and features in the embodiments may be combined with each other without conflict.

[0032] In one embodiment, an inertial measurement unit (IMU) is a common sensor used to obtain the posture information of a vehicle. The posture and displacement information of the vehicle can be analyzed through the IMU data to assist in the control and navigation of the vehicle. Since the IMU data will be affected by the installation angle, the installation angle of the IMU needs to be calibrated when using the IMU to analyze the vehicle. The IMU installation angle calibration method in the related art needs to rely on other sensors or complex filter models, or needs to predetermine the initial value of the IMU installation angle before error calibration, and also needs to be implemented in a complex application environment. For example, it is necessary to use an extra-long straight runway to allow the vehicle to reach a higher speed or acceleration for error calibration, so the calculation cost is high and the calculation efficiency is low.

[0033] To solve the above problems, the embodiment of the present application provides a method for calibrating an installation angle, by defining a first coordinate system corresponding to the IMU according to the first IMU data obtained from the inertial measurement unit IMU of the vehicle, and determining the first rotation angle of the first coordinate system compared to the second coordinate system where the vehicle is located; updating the first coordinate system based on the first rotation angle to obtain the third coordinate system corresponding to the IMU; obtaining the second IMU data of the vehicle, extracting the target peak data from the second IMU data; determining the second rotation angle of the third coordinate system compared to the second coordinate system based on the target peak data; determining the installation angle of the IMU compared to the vehicle based on the first rotation angle and the second rotation angle. It is possible to calibrate the installation angle of the IMU according to the IMU data of the vehicle in different states without installing other sensors or using complex models, and without relying on complex application environments. The installation angle of the IMU installed at any angle at any position of the vehicle can be calibrated in real time, thereby reducing the cost and difficulty of IMU calibration and improving the efficiency of IMU calibration. In addition, the accuracy of IMU installation angle calibration can be further improved with the help of sensor data obtained by other sensors.

[0034] Figure 1 This is a schematic diagram of the structure of a vehicle-mounted device provided in an embodiment of the present application. The embodiment of the present application does not impose any limitation on the specific type of the vehicle-mounted device.

[0035] like Figure 1 As shown, the vehicle-mounted device 10 can be installed in a vehicle 1, and the vehicle-mounted device 10 can include a communication module 101, a memory 102, a processor 103, an input / output (I / O) interface 104, and a bus 105. The processor 103 is coupled to the communication interface 101, the memory 102, and the I / O interface 104 through the bus 105.

[0036] The communication module 101 may include a wired communication module and / or a wireless communication module. The wired communication module may provide one or more wired communication solutions such as universal serial bus (USB), controller area network bus (CAN), local interconnect network (LIN) and Flexray vehicle network standard. The wireless communication module may provide one or more wireless communication solutions such as wireless fidelity (Wi-Fi), bluetooth (BT), mobile communication network, frequency modulation (FM), near field communication technology (NFC), infrared technology (IR), etc.

[0037] The memory 102 may include one or more random access memories (RAM) and one or more non-volatile memories (NVM). The random access memory can be directly read and written by the processor 103, and can be used to store executable programs (such as machine instructions) of the operating system or other running programs, and can also be used to store user and application data. The random access memory may include static random-access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), etc.

[0038] The non-volatile memory may also store executable programs and user and application data, etc., and may be pre-loaded into the random access memory for direct reading and writing by the processor 110. The non-volatile memory may include a disk storage device and a flash memory.

[0039] The memory 102 is used to store one or more computer programs. The one or more computer programs are configured to be executed by the processor 103. The one or more computer programs include a plurality of instructions, and when the plurality of instructions are executed by the processor 103, the installation angle calibration method executed on the vehicle-mounted device 10 can be implemented.

[0040] In other embodiments, the vehicle-mounted device 10 further includes an external memory interface for connecting to an external memory to expand the storage capacity of the vehicle-mounted device 10 .

[0041] The processor 103 may include one or more processing units, for example, the processor 103 may include an application processor (AP), a modem processor, a graphics processor (GPU), an image signal processor (ISP), a controller, a video codec, a digital signal processor (DSP), a baseband processor, and / or a neural-network processing unit (NPU), etc. Different processing units may be independent devices or integrated into one or more processors.

[0042] The processor 103 provides computing and control capabilities. For example, the processor 103 is used to execute a computer program stored in the memory 102 to implement the above-mentioned installation angle calibration method.

[0043] The I / O interface 104 is used to provide a channel for user input or output. For example, the I / O interface 104 can be used to connect various input and output devices, such as a mouse, keyboard, touch device, display screen, etc., so that the user can enter information or visualize information.

[0044] The I / O interface 104 may also be used to provide a channel for data transmission with the inertial measurement unit 106 . For example, the I / O interface 104 may be used to obtain IMU data (eg, first IMU data, second IMU data, etc.) from the inertial measurement unit 106 .

[0045] The inertial measurement unit 106 includes at least one inertial measurement unit installed in the vehicle 1, which is used to measure the three-axis attitude angle (or angular rate) and acceleration of the vehicle. The inertial measurement unit includes multiple gyroscopes and accelerometers. For example, the inertial measurement device includes three sets of gyroscopes and accelerometers, each set of gyroscopes and accelerometers can be used to measure the angular acceleration and linear acceleration of the vehicle in three dimensions; by integrating the acceleration and superimposing the initial velocity and position, the inertial measurement unit can obtain the movement direction and speed of the vehicle in the spatial position. For example Figure 2 As shown, it is an example diagram of the installation position of the inertial measurement unit in the vehicle provided by an embodiment of the present application. The inertial measurement unit can be installed at any position of the vehicle.

[0046] The bus 105 is at least used to provide a channel for mutual communication among the communication module 101 , the memory 102 , the processor 103 , and the I / O interface 104 in the vehicle-mounted device 10 .

[0047] It is understood that the structure illustrated in the embodiment of the present application does not constitute a specific limitation on the vehicle-mounted device 10. In other embodiments of the present application, the vehicle-mounted device 10 may include more or fewer components than shown in the figure, or combine certain components, or separate certain components, or arrange the components differently. The components shown in the figure may be implemented in hardware, software, or a combination of software and hardware.

[0048] Figure 3 : is a flow chart of a method for calibrating an installation angle provided in an embodiment of the present application. The method for calibrating an installation angle is applied to a vehicle-mounted device, for example Figure 1 The vehicle-mounted device 10 specifically includes the following steps. According to different requirements, the order of the steps in the flowchart can be changed, and some can be omitted.

[0049] S31, defining a first coordinate system corresponding to an inertial measurement unit (IMU) of a vehicle according to first IMU data obtained from the IMU, and determining a first rotation angle of the first coordinate system compared to a second coordinate system where the vehicle is located.

[0050] In one embodiment, at least one inertial measurement unit (IMU) is installed in the vehicle, and the vehicle-mounted device can receive a unique identifier of each IMU input by a user to distinguish inertial measurement units installed in different locations.

[0051] In one embodiment, each inertial measurement unit has a corresponding original coordinate system. Since the direction of the IMU data (such as acceleration, angular velocity, etc.) acquired by the IMU is the direction of the original coordinate system itself, when the installation angle of the IMU in the vehicle is unknown, the vehicle's driving data (such as acceleration, angular velocity, etc.) cannot be determined based on the IMU data.

[0052] Therefore, it is necessary to calibrate the installation angle of the IMU in the vehicle to obtain the transformation matrix of the original coordinate system of the IMU compared to the coordinate system of the vehicle (hereinafter referred to as the vehicle coordinate system), so as to transform the IMU according to the transformation matrix and obtain the vehicle's driving data.

[0053] In one embodiment, the Z-axis direction of the vehicle coordinate system may be the direction of gravity when the vehicle is stationary on a horizontal plane (i.e., a direction perpendicular to the ground plane and pointing to the center of the earth), the X-axis direction of the vehicle coordinate system may be the direction of the front of the vehicle, and the Y-axis direction of the vehicle coordinate system may be a direction determined according to the X-axis, the Z-axis, and the right-hand rule. In other embodiments, the Y-axis direction of the vehicle coordinate system may also be determined according to the left-hand rule.

[0054] In one embodiment, after the IMU is installed in the vehicle, due to the different installation angles of the IMU in the vehicle, the transformation matrices between the original coordinate systems of different IMUs are different from those between the vehicle coordinate systems. Figure 2 As shown, the original coordinate system of the inertial measurement unit 201 is represented by X 201 Y 201 Z 201 , the original coordinate system of the inertial measurement unit 202 is represented by X 202 Y 202 Z 202 , the original coordinate system of the inertial measurement unit 203 is represented by X 203 Y 203 Z 203 , the vehicle coordinate system is expressed as XvYvZv. It can be seen that the transformation matrix between the original coordinate system of different IMUs and the coordinate system of the vehicle is different.

[0055] In one embodiment, the original coordinate system of the inertial measurement unit can be determined according to the left-hand rule or the right-hand rule. Figure 4 As shown in Figure 2, according to the right-hand rule, the original coordinate system (b-frame) of the inertial measurement unit installed in the vehicle can be roughly Figure 4 The six situations shown in .

[0056] In one embodiment, the transformation matrix of the original coordinate system of the IMU compared to the vehicle coordinate system may include the rotation angle between the two coordinate axes of each dimension (e.g., X dimension, Y dimension, Z dimension) between different coordinate systems, that is, the installation angle of the IMU in the three dimensions of the vehicle. For example, the installation angle of the IMU in the vehicle includes (rollφ, pitchθ, yawψ): rollφ represents the angle of rotation of the IMU around the longitudinal axis of the vehicle in the horizontal plane of the vehicle, pitchθ represents the angle of rotation of the IMU around the horizontal axis of the vehicle in the vertical plane of the vehicle, and yawψ represents the angle of rotation of the IMU around the vertical axis of the vehicle in the vehicle coordinate system.

[0057] Among them, for example Figure 5 As shown in the figure above, the image is an example of the meaning of the installation angle rollφ and pitchθ of the IMU in the vehicle; after obtaining the installation angle rollφ and pitchθ, it can be Figure 5 As shown in the image below, the horizontal plane of the IMU is corrected to be consistent with the horizontal plane of the vehicle; thereafter, the IMU calibration can be completed by simply obtaining the installation angle yawψ. Figure 6 The vehicle coordinate system is shown in FIG. 1 , and each rotation angle in (rollφ, pitchθ, yawψ) is defined as a positive rotation direction. In the following embodiments, the following Figure 6 The positive direction of the rotation angle shown is used as an example.

[0058] However, the method for obtaining the installation angle yawψ in the related art often requires the use of other sensors (such as real-time dynamic positioning sensors) or the use of complex calculation models (such as filter models), etc., and also needs to be implemented in a complex application environment. For example, it is necessary to use an extra-long straight runway to allow the vehicle to reach a higher speed or acceleration (to achieve a higher signal-to-noise ratio). The required cost is high and the calculation efficiency is low, and it is impossible to achieve rapid calibration of the IMU installed at any position of the vehicle. The method provided in the embodiment of the present application can solve the above problems and achieve rapid calibration of the IMU installed at any position of the vehicle without additional cost.

[0059] In one embodiment, in order to obtain the installation angles rollφ and pitchθ of the IMU so as to calibrate the horizontal plane of the IMU to be consistent with the horizontal plane of the vehicle, the original coordinate system of the IMU may be updated to the first coordinate system.

[0060] The method defines a first coordinate system corresponding to the inertial measurement unit (IMU) of the vehicle based on first IMU data obtained from the IMU, including: obtaining the IMU data of the vehicle when it is at rest as the first IMU data; determining the maximum value of three original accelerations in the three original coordinate axis directions corresponding to the original coordinate system of the IMU based on the first IMU data, and using the original coordinate axis corresponding to the maximum value as the target coordinate axis; defining a first vertical axis of the first coordinate system based on the target coordinate axis, and determining a first horizontal axis and a first vertical axis of the first coordinate system based on the first vertical axis.

[0061] In one embodiment, the first IMU data of the vehicle when it is stationary may include three components of gravity acceleration in three directions of the original coordinate system of the IMU, that is, three original accelerations in the three original coordinate axis directions corresponding to the original coordinate system of the IMU; the original coordinate axis corresponding to the maximum value of the three original accelerations is used as the target coordinate axis; the first vertical axis of the first coordinate system is defined according to the target coordinate axis, and then the first horizontal axis and the first vertical axis of the first coordinate system are determined according to the first vertical axis.

[0062] For example Figure 4 As shown, taking the original coordinate system of the IMU installed in the vehicle as the fourth case as an example, if the value (or absolute value) of the original acceleration in the direction of the original coordinate axis Xb is the largest, then the original coordinate axis Xb is used as the target coordinate axis; since the direction of the target coordinate axis Xb points to the ground, when defining the first vertical axis of the first coordinate system according to the target coordinate axis Xb, let the first vertical axis Zp = -Xb, so as to adjust the rotation angle between the Z-axis direction of the first coordinate system and the Z-axis direction of the coordinate system where the vehicle is located to an acute angle; thereafter, the other two coordinate axes of the original coordinate system can be adjusted according to the rule used to establish the vehicle coordinate system and the direction of the first vertical axis. For example, if the vehicle coordinate system conforms to the right-hand rule, then according to the right-hand rule, let the first horizontal axis Xp = original coordinate axis Zb, let the first vertical axis Yp = original coordinate axis Yb, and obtain the first coordinate system XpYpZp.

[0063] In one embodiment, the second coordinate system where the vehicle is located is the above-mentioned vehicle coordinate system XvYvZv, and the second longitudinal axis Zv of the second coordinate system is in the same direction as the gravity acceleration.

[0064] In one embodiment, determining the first rotation angle of the first coordinate system relative to the second coordinate system where the vehicle is located includes: determining a first acceleration in the first horizontal axis direction of the first coordinate system and a second acceleration in the first vertical axis direction of the first coordinate system according to the first IMU data; determining a first angle between the first horizontal axis of the first coordinate system and the second horizontal axis of the second coordinate system based on an inverse sine function of the ratio of gravity acceleration to the first acceleration; determining a second angle between the first vertical axis of the first coordinate system and the second vertical axis of the second coordinate system based on an inverse sine function of the ratio of gravity acceleration to the second acceleration; and using the first angle and the second angle as the first rotation angle between the first coordinate system and the second coordinate system.

[0065] In one embodiment, the first acceleration and the second acceleration can be obtained according to the transformation relationship between the coordinate axes of the original coordinate system and the first coordinate system. Specifically, the first horizontal axis Xp in the first coordinate system = the original coordinate axis Zb, then the first acceleration aX is the original acceleration in the direction of the original coordinate axis Zb in the first IMU data; the first vertical axis Yp in the first coordinate system = the original coordinate axis Yb, then the second acceleration aY is the original acceleration in the direction of the original coordinate axis Yb in the first IMU data.

[0066] In one embodiment, when determining the first angle pitchθ between the first horizontal axis of the first coordinate system and the second horizontal axis of the second coordinate system based on the inverse sine function of the ratio of the gravitational acceleration to the first acceleration, the formula that can be used includes: θ=arcsin(aX / g), where aX represents the first acceleration corresponding to the first horizontal axis Xp, and g represents the gravitational acceleration=9.8m / s 2 For example, as shown in the figure, θ = arcsin (aX / g). For example, if aX = -1.7m / s 2 , g = 9.8 m / s 2 , then θ=arcsin(-1.7 / 9.8)*180 / π=-10deg(degrees); Xp points below the horizontal plane, so the gravitational acceleration component aX is negative.

[0067] Similarly, when determining the second angle rollφ between the first longitudinal axis of the first coordinate system and the second longitudinal axis of the second coordinate system based on the arcsine function of the ratio of the gravitational acceleration to the second acceleration, the formula that can be used includes: φ=-arcsin(aY / g), where aY represents the second acceleration corresponding to the first longitudinal axis Yp. For example, aY=4.9m / s 2 , g = 9.8 m / s 2 , then φ=-asin(4.9 / 9.8)*180 / π=-30deg; Yp points to the horizontal plane, so the gravitational acceleration component aY is positive.

[0068] S32: Update the first coordinate system based on the first rotation angle to obtain a third coordinate system corresponding to the IMU.

[0069] In one embodiment, the first coordinate system is updated based on the first rotation angle to obtain a third coordinate system corresponding to the IMU, including: constructing a rotation matrix based on the first rotation angle, rotating the first horizontal axis and the first vertical axis of the first coordinate system according to the rotation matrix to obtain the third coordinate system, and the third vertical axis of the third coordinate system is parallel to the second vertical axis of the second coordinate system.

[0070] In one embodiment, after obtaining the first rotation angle, namely the installation angle rollφ and pitchθ, the following can be done: Figure 5 As shown in the image below, the horizontal plane of the IMU is corrected to be consistent with the horizontal plane of the vehicle, and the third coordinate system corresponding to the IMU is obtained. The rotation matrix constructed based on the first rotation angle is used to rotate the first horizontal axis and the first vertical axis of the first coordinate system so that the third vertical axis of the updated third coordinate system is parallel to the second vertical axis of the second coordinate system.

[0071] In one embodiment, for example Figure 5 As shown in the image below, the third coordinate system and the vehicle coordinate system have not yet been aligned. At this time, the vertical axes of the third coordinate system and the vehicle coordinate system are parallel to each other and there is an installation angle yawψ.

[0072] In one embodiment, Figure 7 The inertial measurement unit 202 in the upper middle image is used as an example. As indicated by the arrow in the upper image, the horizontal plane of the inertial measurement unit 202 is corrected to be consistent with the horizontal plane of the vehicle, and the third coordinate system corresponding to the IMU is obtained; the horizontal plane of the third coordinate system of the inertial measurement unit 202 can be referred to Figure 7 Example image from a top-down perspective in the middle and lower part.

[0073] S33, obtaining second IMU data of the vehicle, and extracting target peak data from the second IMU data.

[0074] In one embodiment, acquiring the second IMU data of the vehicle and extracting the target peak data from the second IMU data includes:

[0075] (1) acquiring IMU data of the vehicle when turning as the second IMU data;

[0076] In one embodiment, since the third vertical axis of the third coordinate system of the IMU is parallel to the second vertical axis of the vehicle coordinate system, i.e., the second coordinate system, the angular velocity (unit: degree / second) in the direction of the third vertical axis detected by the IMU when the vehicle turns at a constant speed can be used to indicate the vehicle's rotational angular velocity, and the acceleration in the direction of the third horizontal axis and the acceleration in the direction of the third longitudinal axis detected by the IMU when the vehicle turns at a constant speed can be used to indicate the centripetal acceleration of the vehicle in two directions.

[0077] In one embodiment, IMU data of the vehicle when turning can be obtained at any curve as the second IMU data.

[0078] In one embodiment, for example Figure 8As shown, it is an example diagram of the second IMU data provided by the embodiment of the present application, wherein the horizontal axis represents time, the left vertical axis represents the value of acceleration, and the right vertical axis represents the value of angular velocity; the X acceleration represents the centripetal acceleration in the third horizontal axis direction of the third coordinate system, the Y acceleration represents the centripetal acceleration in the third vertical axis direction of the third coordinate system, and the Z angular velocity represents the angular velocity in the third vertical axis direction of the third coordinate system. Wherein, when the Z angular velocity is 0, it means that the vehicle is traveling in a straight line; when the third coordinate system and the second coordinate system both conform to the right-hand rule, the Z angular velocity is greater than 0, which means that the vehicle is turning right, and the Z angular velocity is less than 0, which means that the vehicle is turning left. When the X acceleration, Y acceleration, and Z angular velocity are all equal to 0, it means that the vehicle is stationary.

[0079] (2) determining, from the second IMU data, a peak angular velocity in the third vertical axis direction of the third coordinate system that is greater than a preset threshold and a peak time node corresponding to the peak angular velocity;

[0080] In one embodiment, data may be extracted from the second IMU data using a sliding window with a fixed length according to the principle of a real-time sliding window, wherein the fixed length represents a preset time length.

[0081] In one embodiment, the second IMU data may contain a lot of noise interference. In order to reduce the error caused by the noise, the second IMU data may be smoothed first, and then the angular velocity peak value in the third vertical axis direction is selected from the data greater than the preset threshold, wherein the angular velocity peak value represents the peak data with the largest absolute value of the angular velocity within the second IMU data corresponding to the preset time length in each sliding window. The preset threshold value may be selected according to actual needs, such as 0.001. For example Figure 8 As shown, the selected angular velocity peak is the peak within the circle.

[0082] (3) Extracting the third acceleration in the third horizontal axis direction and the fourth acceleration in the third vertical axis direction of the third coordinate system corresponding to the peak time node from the second IMU data, and using the third acceleration and the fourth acceleration as the target peak data.

[0083] In one embodiment, in order to determine the rotation angle in the third vertical axis direction, the third acceleration in the third horizontal axis direction and the fourth acceleration in the third longitudinal axis direction of the third coordinate system need to be used, so the target peak data corresponding to the peak time node needs to be extracted.

[0084] S34: Determine a second rotation angle of the third coordinate system relative to the second coordinate system based on the target peak data.

[0085] In one embodiment, determining the second rotation angle of the third coordinate system relative to the second coordinate system based on the target peak data includes: determining the angle between the third horizontal axis of the third coordinate system and the direction of the centripetal force exerted on the vehicle when the second IMU data is obtained based on the inverse tangent function of the ratio of the fourth acceleration to the third acceleration; determining the second rotation angle according to the angle and the turning direction of the vehicle when the second IMU data is obtained.

[0086] In one embodiment, for example Fig. 9 As shown, it is an example diagram of the centripetal force exerted on the vehicle when driving on a curve provided by an embodiment of the present application. Among them, the speed direction of vehicle 1 is the direction of the second horizontal axis Xv of the second coordinate system, and the direction of the Xv axis is perpendicular to the direction of the centripetal force exerted on the vehicle. After the angle λr between the Xp axis of the inertial measurement unit 202 and the centripetal force direction is obtained by the inverse tangent function of the ratio of the fourth acceleration to the third acceleration, the second rotation angle ψ can be determined according to the angle λr and the turning direction of the vehicle 1 when the second IMU data of the inertial measurement unit 202 is obtained. Among them, λr=arctan(ay / ax)*180 / π, ay represents the fourth acceleration, and ax represents the third acceleration.

[0087] In one embodiment, the determining the second rotation angle according to the angle and the turning direction of the vehicle when the second IMU data is obtained includes: when the turning direction of the vehicle is a right turn, determining the second rotation angle according to the difference between the angle and the right angle; when the turning direction of the vehicle is a left turn, determining the second rotation angle according to the sum of the angle and the right angle. The turning direction of the vehicle can be determined according to the positive and negative values ​​of the angular velocity in the second IMU data. Specifically, refer to step S33 for determining the turning direction of the vehicle. Figure 8 Description.

[0088] In one embodiment, since the direction of the centripetal force received by the vehicle when the Xv axis is turned to the left is 90 degrees to the left, and the direction of the centripetal force received by the vehicle when the Xv axis is turned to the right is 90 degrees to the right, when the vehicle turns right, the second rotation angle ψ is determined according to the turning direction of the vehicle and the angle λr, the formula that can be used includes: when the vehicle turns right, let ψ=λr-90°; when the vehicle turns left, let ψ=λr+90°. The turning direction of the vehicle can be determined according to the positive or negative Z angular velocity in the second IMU data.

[0089] For example, when the Z angular velocity is positive, the vehicle is turning right, ax=0.004, ay=0.001, and the calculation method of λr includes: λr=arctan2(ay / ax)*180 / π=14deg, then yawψ=14–90=-76deg; or, when the Z angular velocity is negative, the vehicle is turning left, ax=-0.004, ay=-0.001, and the calculation method of λr includes: λr=atan2(ay / ax)*180 / π=194deg, then yawψ=194+90=284deg.

[0090] In one embodiment, in order to improve the calculation accuracy of the second rotation angle ψ in the above embodiment, the method further includes: performing data optimization processing on multiple angles determined according to multiple second IMU data, and determining the second rotation angle according to the optimal angle obtained after the data optimization processing. The data optimization processing may include removing the maximum and minimum values ​​of the multiple angles and then taking the average value.

[0091] S35: Determine an installation angle of the IMU relative to the vehicle based on the first rotation angle and the second rotation angle.

[0092] In one embodiment, the first rotation angles rollφ and pitchθ and the second rotation angle yawψ obtained by the above embodiment can be used as the installation angle of the IMU relative to the vehicle. The coordinate system of the IMU can be aligned with the vehicle coordinate system by rotating the third vertical axis of the third coordinate system according to the second rotation angle yawψ. For example Fig.10 As shown, compared to Figure 7 For example, in the top-down view below, Fig.10 The middle arrow indicates a top view of the IMU coordinate system after the third vertical axis is rotated according to the second rotation angle yawψ, and is aligned with the vehicle coordinate system.

[0093] In one embodiment, after obtaining the installation angle of the IMU relative to the vehicle, the method further includes: obtaining third IMU data when the target user is driving the vehicle; calibrating the third IMU data according to the installation angle to obtain driving data of the vehicle; performing a driving behavior analysis on the target user based on the driving data of the vehicle, the driving behavior analysis including determining one or more driving behaviors of the target user including sudden acceleration, sudden deceleration, and sharp turning; and scoring the driving behavior of the target user based on the results of the driving behavior analysis.

[0094] Among them, the third IMU data is calibrated according to the installation angle, and when the driving data of the vehicle is obtained, the calibration matrix can be constructed using the installation angle, and the driving data of the vehicle is obtained by multiplying the vector composed of the third IMU data and the calibration matrix. When analyzing the driving behavior of the user, it can be judged according to a pre-set numerical range. The more the above driving behaviors, the lower the driving stability of the target user, and therefore the lower the score.

[0095] In other embodiments, after obtaining the installation angle of the IMU relative to the vehicle, the three-dimensional posture of the vehicle, such as pitch, roll, heading, etc., can also be obtained based on the IMU data, so as to correct the vehicle heading and speed in combination with the motion trajectory setting in the inertial navigation system to achieve the navigation function. In addition, the calibrated IMU can also be used to assist in the calibration and calibration of other sensors installed on the vehicle (such as wheel speed sensors, etc.).

[0096] In one embodiment, the installation angle calibration method provided in the embodiment of the present application is defined according to the first IMU data obtained from the inertial measurement unit IMU of the vehicle, and the first rotation angle of the first coordinate system compared to the second coordinate system where the vehicle is located is determined; the first coordinate system is updated based on the first rotation angle to obtain the third coordinate system corresponding to the IMU; the second IMU data of the vehicle is obtained, and the target peak data is extracted from the second IMU data; the second rotation angle of the third coordinate system compared to the second coordinate system is determined based on the target peak data; the installation angle of the IMU compared to the vehicle is determined based on the first rotation angle and the second rotation angle. It is possible to calibrate the installation angle of the IMU according to the IMU data of the vehicle in different states without installing other sensors or using complex models, and the installation angle of the IMU installed at any angle at any position of the vehicle can be instantly calibrated, thereby reducing the cost and difficulty of IMU calibration and improving the efficiency of IMU calibration.

[0097] Fig.11 It is a structural diagram of an installation angle calibration device provided in one embodiment of the present application.

[0098] In some embodiments, the installation angle calibration device 40 may include a plurality of functional modules composed of computer program segments. The computer programs of the various program segments in the installation angle calibration device 40 may be stored in a memory of the vehicle-mounted device and executed by at least one processor to execute (see Figure 3 Description) Installation angle calibration function.

[0099] In this embodiment, the installation angle calibration device 40 can be divided into multiple functional modules according to the functions it performs. The functional modules may include: a determination module 401, an update module 402, and an extraction module 403. The module referred to in this application refers to a series of computer program segments that can be executed by at least one processor and can complete fixed functions, which are stored in a memory. In this embodiment, the functional implementation method of each module in the installation angle calibration device 40 can refer to the above definition of the installation angle calibration method, and will not be repeated here.

[0100] The determination module 401 is used to define a first coordinate system corresponding to an inertial measurement unit (IMU) of a vehicle according to first IMU data obtained from the IMU, and to determine a first rotation angle of the first coordinate system compared to a second coordinate system where the vehicle is located.

[0101] The updating module 402 is used to update the first coordinate system based on the first rotation angle to obtain a third coordinate system corresponding to the IMU.

[0102] The extraction module 403 is used to obtain the second IMU data of the vehicle and extract the target peak data from the second IMU data.

[0103] The determination module 401 is further configured to determine a second rotation angle of the third coordinate system relative to the second coordinate system based on the target peak data.

[0104] The determination module 401 is further configured to determine an installation angle of the IMU relative to the vehicle based on the first rotation angle and the second rotation angle.

[0105] An embodiment of the present application further provides a computer-readable storage medium, on which a computer program is stored. The computer program includes program instructions. The method implemented when the program instructions are executed can refer to the methods in the above-mentioned embodiments of the present application.

[0106] The computer-readable storage medium may be an internal memory of the vehicle-mounted device described in the above embodiment, such as a hard disk or memory of the vehicle-mounted device. The computer-readable storage medium may also be an external storage device of the vehicle-mounted device, such as a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), etc. equipped on the vehicle-mounted device.

[0107] In some embodiments, the computer-readable storage medium may include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application required for at least one function, etc.; the data storage area may store data created according to the use of the vehicle-mounted device, etc.

[0108] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0109] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0110] In the embodiments provided in the present application, it should be understood that the disclosed devices / terminal equipment and methods can be implemented in other ways. For example, the device / terminal equipment embodiments described above are only schematic. For example, the division of the modules or units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0111] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0112] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A method for calibrating an installation angle, It is characterized in that The method comprises: According to first IMU data obtained from an inertial measurement unit (IMU) of the vehicle, a first coordinate system corresponding to the IMU is defined, and a first rotation angle of the first coordinate system compared to a second coordinate system where the vehicle is located is determined; Update the first coordinate system based on the first rotation angle to obtain a third coordinate system corresponding to the IMU; Acquire second IMU data of the vehicle, and extract target peak data from the second IMU data; Determining a second rotation angle of the third coordinate system relative to the second coordinate system based on the target peak data; Based on the first rotation angle and the second rotation angle, a mounting angle of the IMU relative to the vehicle is determined.

2. The installation angle calibration method according to claim 1, It is characterized in that The method of defining a first coordinate system corresponding to an inertial measurement unit (IMU) of a vehicle according to first IMU data obtained from the IMU includes: Acquire IMU data of the vehicle when it is in a stationary state as the first IMU data; Determine the maximum value of three original accelerations in the directions of three original coordinate axes corresponding to the original coordinate system of the IMU according to the first IMU data, and use the original coordinate axis corresponding to the maximum value as the target coordinate axis; A first vertical axis of the first coordinate system is defined based on the target coordinate axis, and a first horizontal axis and a first vertical axis of the first coordinate system are determined according to the first vertical axis.

3. The installation angle calibration method according to claim 1, It is characterized in that The second vertical axis of the second coordinate system is in the same direction as the gravitational acceleration; and determining the first rotation angle of the first coordinate system compared to the second coordinate system where the vehicle is located includes: Determine a first acceleration in a first horizontal axis direction in the first coordinate system and a second acceleration in a first vertical axis direction in the first coordinate system according to the first IMU data; determining a first angle between a first horizontal axis of the first coordinate system and a second horizontal axis of the second coordinate system based on an inverse sine function of a ratio of the gravitational acceleration to the first acceleration; determining a second angle between a first longitudinal axis of the first coordinate system and a second longitudinal axis of the second coordinate system based on an inverse sine function of a ratio of the gravitational acceleration to the second acceleration; The first angle and the second angle are used as the first rotation angle between the first coordinate system and the second coordinate system.

4. The installation angle calibration method according to claim 1, It is characterized in that The updating of the first coordinate system based on the first rotation angle to obtain a third coordinate system corresponding to the IMU includes: A rotation matrix is ​​constructed based on the first rotation angle, and the first horizontal axis and the first vertical axis of the first coordinate system are rotated according to the rotation matrix to obtain the third coordinate system, wherein the third vertical axis of the third coordinate system is parallel to the second vertical axis of the second coordinate system.

5. The installation angle calibration method according to claim 1, It is characterized in that The acquiring the second IMU data of the vehicle and extracting the target peak data from the second IMU data includes: Acquire IMU data of the vehicle when turning as the second IMU data; Determine, from the second IMU data, a peak angular velocity in the third vertical axis direction of the third coordinate system that is greater than a preset threshold and a peak time node corresponding to the peak angular velocity; The third acceleration in the third horizontal axis direction and the fourth acceleration in the third vertical axis direction of the third coordinate system corresponding to the peak time node are extracted from the second IMU data, and the third acceleration and the fourth acceleration are used as the target peak data.

6. The installation angle calibration method according to claim 5, It is characterized in that The determining, based on the target peak data, a second rotation angle of the third coordinate system compared to the second coordinate system comprises: Determine, based on an inverse tangent function of the ratio of the fourth acceleration to the third acceleration, an angle between a third horizontal axis of the third coordinate system and a direction of the centripetal force applied to the vehicle when acquiring the second IMU data; The second rotation angle is determined according to the included angle and the turning direction of the vehicle when the second IMU data is acquired.

7. The installation angle calibration method according to claim 6, It is characterized in that Determining the second rotation angle according to the included angle and the turning direction of the vehicle when acquiring the second IMU data includes: When the turning direction of the vehicle is right turn, determining the second rotation angle according to the difference between the included angle and the right angle; When the turning direction of the vehicle is left turn, the second rotation angle is determined according to the sum of the included angle and the right angle.

8. The installation angle calibration method according to claim 6, It is characterized in that The method further comprises: Data optimization processing is performed on multiple angles determined according to multiple second IMU data, and the second rotation angle is determined according to the optimal angle obtained after the data optimization processing.

9. A vehicle-mounted device, It is characterized in that The vehicle-mounted device includes a memory and at least one processor, wherein the memory stores at least one instruction, and when the at least one instruction is executed by the at least one processor, the installation angle calibration method as described in any one of claims 1 to 8 is implemented.

10. A computer-readable storage medium having a computer program stored thereon, It is characterized in that When the computer program is executed by a processor, the installation angle calibration method as described in any one of claims 1 to 8 is implemented.

Images