Millimeter wave radar-IMU (Inertial Measurement Unit) external parameter calibration method, device and equipment and storage medium

Abstract

The invention relates to a millimeter wave radar-IMU external parameter calibration method, device and equipment and a storage medium, and the method comprises the steps: obtaining the global positioning coordinate of at least one corner reflector, the global positioning coordinate of a motion carrier, and a plurality of initial point cloud coordinates of each corner reflector; determining a target point cloud coordinate of each corner reflector from the plurality of initial point cloud coordinates of each corner reflector based on the global positioning coordinate of each corner reflector and the global positioning coordinate of the motion carrier; and converting the global positioning coordinate of each corner reflector into an IMU coordinate system to obtain an IMU coordinate of each corner reflector, carrying out coordinate association on the target point cloud coordinate of each corner reflector and the IMU coordinate of each corner reflector, and solving based on an iterative least square method to obtain an external parameter of the millimeter wave radar-IMU. Therefore, the problem of insufficient precision and robustness of millimeter wave radar-IMU calibration in a complex environment is solved, and the calibration precision and the system robustness in a dynamic environment are greatly improved.

Description

Technical Field

[0001] The present application relates to the technical field of external parameter calibration, and in particular to an external parameter calibration method, device, equipment and storage medium for a millimeter wave radar-IMU. Background Art

[0002] With the growing demand for high-precision positioning, navigation, and perception in the fields of autonomous driving, drones, and robots, millimeter-wave radar and IMU (Inertial Measurement Unit) have become important sensors for achieving high-precision spatial perception and dynamic positioning. Accurate calibration of millimeter-wave radar and IMU is a key step in achieving high-precision pose and velocity estimation of the millimeter-wave radar-IMU combined system. This calibration process not only provides the necessary coordinate system conversion for converting the target position detected by the millimeter-wave radar to the navigation coordinate system, but also lays the foundation for further sensor fusion.

[0003] The related technology proposes an odometer-based method to calibrate the millimeter-wave radar-IMU external parameters, which estimates the vehicle's own posture using the millimeter-wave radar and IMU respectively, and then correlates the posture information of the two to solve the external parameters.

[0004] However, in practical applications, the calibration accuracy of millimeter-wave radar-IMU is limited by multiple factors. First, millimeter-wave radar often uses corner reflectors (hereinafter referred to as corner reflectors) as targets, but the limited number of corner reflectors leads to insufficient observation data, making the calibration results dependent on limited observations, which in turn limits the accuracy. Secondly, the point cloud generated by millimeter-wave radar is sparse and sensitive to the reflection intensity of different materials, making it difficult to extract features from specific areas of interest. Due to the scarcity of effective observations, it is difficult for millimeter-wave radar to achieve high-precision pose estimation through methods such as SLAM, and there is an error accumulation problem when IMU calculates pose by integration, which further affects the calibration accuracy. In addition, in dynamic environments such as shipborne systems, the installation positions of millimeter-wave radars and IMUs will be affected by external interference such as water waves as the carrier moves, causing the observations to be interfered with by noise such as background objects and multipath signals, affecting the stability and reliability of the calibration. Summary of the invention

[0005] The present application provides a millimeter-wave radar-IMU external parameter calibration method, device, equipment and storage medium to solve the problem of insufficient accuracy and robustness of millimeter-wave radar-IMU calibration in complex environments, and greatly improves the calibration accuracy and system robustness in dynamic environments.

[0006] The first aspect of the present application provides an external parameter calibration method for a millimeter wave radar-IMU, comprising the following steps:

[0007] Acquire the global positioning coordinates of at least one corner reflector, the global positioning coordinates of the moving carrier, and a plurality of initial point cloud coordinates of each corner reflector;

[0008] Based on the global positioning coordinates of each corner reflector and the global positioning coordinates of the moving carrier, determining the target point cloud coordinates of each corner reflector from the multiple initial point cloud coordinates of each corner reflector;

[0009] The global positioning coordinates of each corner reflector are converted to the IMU coordinate system to obtain the IMU coordinates of each corner reflector, the target point cloud coordinates of each corner reflector and the IMU coordinates of each corner reflector are coordinate-associated, and the external parameters of the millimeter-wave radar-IMU are obtained based on the iterative least squares method.

[0010] Optionally, in some embodiments, determining the point cloud coordinates of each corner reflector from a plurality of initial point cloud coordinates of each corner reflector based on the global positioning coordinates of each corner reflector and the global positioning coordinates of the moving carrier comprises:

[0011] Determine a reference distance between each corner reflector and the moving carrier according to the global positioning coordinates of each corner reflector and the global positioning coordinates of the moving carrier;

[0012] The target point cloud coordinates of each corner reflector are determined from the multiple initial point cloud coordinates of each corner reflector according to the reference distance.

[0013] Optionally, in some embodiments, determining the reference distance between each corner reflector and the moving carrier according to the global positioning coordinates of each corner reflector and the global positioning coordinates of the moving carrier comprises:

[0014] Based on a preset distance calculation formula, a reference distance between each corner reflector and the moving carrier is determined according to the global positioning coordinates of each corner reflector and the global positioning coordinates of the moving carrier, wherein the preset distance calculation formula is:

[0015]

[0016] Among them, D IR,k is the reference distance, is the global positioning coordinate of the i-th reflector, is the global positioning coordinates of the moving carrier.

[0017] Optionally, in some embodiments, converting the global positioning coordinates of each corner reflector into an IMU coordinate system to obtain the IMU coordinates of each corner reflector includes:

[0018] Get the IMU pose sequence based on the preset GNSS / INS combination algorithm;

[0019] Convert the global positioning coordinates of each corner reflector into a navigation coordinate system to obtain the navigation coordinate system coordinates of each corner reflector;

[0020] The IMU coordinates of each corner reflector are obtained according to the posture sequence of the IMU and the navigation coordinate system coordinates of each corner reflector.

[0021] The second aspect of the present application provides an external parameter calibration device for a millimeter wave radar-IMU, including:

[0022] An acquisition module, used to acquire the global positioning coordinates of at least one corner reflector, the global positioning coordinates of the motion carrier, and a plurality of initial point cloud coordinates of each corner reflector;

[0023] A determination module, configured to determine the target point cloud coordinates of each corner reflector from a plurality of initial point cloud coordinates of each corner reflector based on the global positioning coordinates of each corner reflector and the global positioning coordinates of the moving carrier;

[0024] The association module is used to convert the global positioning coordinates of each corner reflector into the IMU coordinate system to obtain the IMU coordinates of each corner reflector, coordinately associate the target point cloud coordinates of each corner reflector with the IMU coordinates of each corner reflector, and solve the external parameters of the millimeter wave radar-IMU based on the iterative least squares method.

[0025] Optionally, in some embodiments, the determining module includes:

[0026] A first determining unit, configured to determine a reference distance between each corner reflector and the moving carrier according to the global positioning coordinates of each corner reflector and the global positioning coordinates of the moving carrier;

[0027] The second determining unit is used to determine the target point cloud coordinates of each corner reflector from the multiple initial point cloud coordinates of each corner reflector according to the reference distance.

[0028] Optionally, in some embodiments, the first determining unit includes:

[0029] The calculation subunit is used to determine the reference distance between each corner reflector and the moving carrier according to the global positioning coordinates of each corner reflector and the global positioning coordinates of the moving carrier based on a preset distance calculation formula, wherein the preset distance calculation formula is:

[0030]

[0031] Among them, DIR,k is the reference distance, is the global positioning coordinate of the i-th reflector, is the global positioning coordinates of the moving carrier.

[0032] Optionally, in some embodiments, the association module includes:

[0033] A first generating unit, used for obtaining a pose sequence of the IMU based on a preset GNSS / INS combination algorithm;

[0034] A switching unit, used for converting the global positioning coordinates of each corner reflector into a navigation coordinate system to obtain the navigation coordinate system coordinates of each corner reflector;

[0035] The second generating unit is used to obtain the IMU coordinates of each corner reflector according to the posture sequence of the IMU and the navigation coordinate system coordinates of each corner reflector.

[0036] The third aspect of the present application provides an electronic device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the external parameter calibration method of the millimeter-wave radar-IMU as described in the above embodiment.

[0037] The fourth aspect of the present application provides a computer-readable storage medium having a computer program stored thereon, which is executed by a processor to implement the external parameter calibration method of the millimeter-wave radar-IMU as described in the above embodiment.

[0038] Therefore, this application has at least the following beneficial effects:

[0039] (1) The present application adopts a moving carrier method to observe the angle inversion, and the obtained multiple angle inversion sequences can make up for the limited calibration accuracy caused by the insufficient number of angle inversions.

[0040] (2) This application uses GNSS to screen the point cloud coordinates of the inverse angle, which effectively suppresses the influence of noise and gross errors in the initial stage.

[0041] (3) This application introduces GNSS assistance. The IMU posture calculated by the GNSS / INS combination can accurately calculate the posture of the IMU in the GNSS coordinate system, thereby inversely transforming the angle into the IMU coordinate system.

[0042] In summary, the present application not only solves the limitations of traditional calibration methods in complex environments, but also greatly improves the calibration accuracy and system robustness in dynamic environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0044] Figure 1 A flowchart of an external parameter calibration method of a millimeter-wave radar-IMU provided according to an embodiment of the present application;

[0045] Figure 2 A schematic diagram of a shipborne millimeter wave radar-IMU external parameter calibration experiment provided according to an embodiment of the present application;

[0046] Figure 3 A schematic diagram of a millimeter wave radar-IMU external parameter provided according to an embodiment of the present application;

[0047] Figure 4 The figure is a schematic diagram of the result of aligning the angle reflection in the millimeter wave radar coordinate system and the IMU coordinate system after the external parameter conversion according to an embodiment of the present application, wherein: Figure 4 (a) is a schematic diagram of the alignment result using the external parameters calculated in the first round of iterations. Figure 4 (b) is a schematic diagram of the alignment result using the external parameters calculated in the 20th round of iterations;

[0048] Figure 5 A flowchart of a millimeter wave radar-IMU calibration method provided according to an embodiment of the present application;

[0049] Figure 6 A block diagram of an external parameter calibration device for a millimeter-wave radar-IMU provided according to an embodiment of the present application;

[0050] Figure 7 It is a schematic diagram of the structure of the device provided according to the embodiment of the present application. DETAILED DESCRIPTION

[0051] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0052] The following describes the external parameter calibration method, device, equipment and storage medium of the millimeter wave radar-IMU of the embodiment of the present application with reference to the accompanying drawings. In view of the problem of insufficient accuracy and robustness in the calibration of the millimeter wave radar-IMU in a complex environment mentioned in the above background technology, the present application provides an external parameter calibration method of the millimeter wave radar-IMU, in which, first, according to the GNSS coordinate sequence of the carrier and the GNSS coordinates of the angular inversion, the distance from the angular inversion to the IMU at different times is calculated, and the angular inversion point cloud coordinates are pre-selected based on this; then, the IMU posture is calculated by the GNSS / INS combined algorithm, and the GNSS coordinates of the angular inversion are converted based on this to obtain the IMU system coordinates of the angular inversion; finally, by associating the point cloud coordinates of the angular inversion and the IMU system coordinates, the millimeter wave radar-IMU external parameters are estimated, and the iterative least squares form is used in the calculation to gradually eliminate gross errors from the pre-selected angular inversion coordinates to improve the accuracy of the external parameter solution.

[0053] Specifically, Figure 1 A flow chart of an external parameter calibration method of a millimeter-wave radar-IMU provided in an embodiment of the present application.

[0054] like Figure 1 As shown, the external parameter calibration method of the millimeter wave radar-IMU includes the following steps:

[0055] In step S101, the global positioning coordinates of at least one corner reflector, the global positioning coordinates of the moving carrier, and a plurality of initial point cloud coordinates of each corner reflector are acquired.

[0056] Among them, the global positioning coordinates are measured by the GNSS RTK method, and the initial point cloud coordinates are measured by millimeter wave radar.

[0057] Specifically, combined Figure 2 As shown, in the embodiment of the present application, three corner reflectors are placed statically on the shore, and the GNSSRTK method is used to measure the accurate GNSS coordinates of the corner reflectors, and the RTK measurement accuracy is at the centimeter level. When the hull is moving, the millimeter-wave radar, IMU, and GNSS are turned on. Among them, the millimeter-wave radar detects the corner reflector to obtain the initial point cloud sequence of the corner reflector; the IMU and GNSS are used to estimate the accurate position and posture of the IMU.

[0058] In step S102, based on the global positioning coordinates of each corner reflector and the global positioning coordinates of the moving carrier, the target point cloud coordinates of each corner reflector are determined from a plurality of initial point cloud coordinates of each corner reflector.

[0059] Further, in some embodiments, based on the global positioning coordinates of each corner reflector and the global positioning coordinates of the motion carrier, the point cloud coordinates of each corner reflector are determined from multiple initial point cloud coordinates of each corner reflector, including: determining a reference distance between each corner reflector and the motion carrier according to the global positioning coordinates of each corner reflector and the global positioning coordinates of the motion carrier; determining the target point cloud coordinates of each corner reflector from the multiple initial point cloud coordinates of each corner reflector according to the reference distance.

[0060] It should be noted that in the embodiments of the present application, Figure 3 As shown, let the millimeter wave radar coordinate system be M, the IMU coordinate system be I, the earth coordinate system be G, and the external reference be Indicates the transformation parameters from the IMU coordinate system to the millimeter wave radar coordinate system, for example, the external parameters in represents the rotation from the I system to the M system, Represents the translation from I system to M system.

[0061] Specifically, in the earth coordinate system G, the angular inverse coordinate measured by GNSS RTK is They represent longitude, latitude, and altitude respectively. Under static conditions, the coordinate values ​​do not change with time.

[0062] In the M coordinate system, the homogeneous coordinate form of the angle inverse is Where i represents the angle number and k represents the time. The IMU coordinates are calculated using the GNSS / INS combination method and are: k represents time.

[0063] After acquiring the global positioning coordinates of at least one corner reflector, the global positioning coordinates of the moving carrier, and multiple initial point cloud coordinates of each corner reflector, the embodiment of the present application can pre-select the radar point cloud.

[0064] The sampling rate of the millimeter wave radar is 20Hz, and the point cloud measured at each moment can be converted into multiple distances. These points are affected by noise and clutter, making it difficult to accurately screen the corner inversion points without other observation assistance. The embodiment of the present application can first convert the point cloud at the kth moment into a distance, that is:

[0065]

[0066] Then pass and Calculate the distance from the inverse angle to the IMU:

[0067]

[0068] In the case of long distance, assuming that the distances to the millimeter-wave radar and the IMU are approximately equal, the reference distance DIR,k Right D i,k Perform pre-screening to obtain the pre-selected corner reverse point cloud sequence

[0069] In step S103, the global positioning coordinates of each corner reflector are converted to the IMU coordinate system to obtain the IMU coordinates of each corner reflector, the target point cloud coordinates of each corner reflector and the IMU coordinates of each corner reflector are coordinate-associated, and the external parameters of the millimeter-wave radar-IMU are obtained based on the iterative least squares method.

[0070] Furthermore, in some embodiments, the global positioning coordinates of each corner reflector are converted to an IMU coordinate system to obtain the IMU coordinates of each corner reflector, including: obtaining the IMU posture sequence based on a preset GNSS / INS combination algorithm; converting the global positioning coordinates of each corner reflector to a navigation coordinate system to obtain the navigation coordinate system coordinates of each corner reflector; and obtaining the IMU coordinates of each corner reflector according to the IMU posture sequence and the navigation coordinate system coordinates of each corner reflector.

[0071] Specifically, when determining the target point cloud coordinates of each corner reflector, the embodiment of the present application can convert the target point cloud coordinates of the corner reflector into the IMU coordinate system.

[0072] Specifically, according to the inverse angular coordinates IMU Coordinates First, convert both to the navigation coordinate system (east-north-up, enu), and get

[0073] Specifically, all longitude and latitude heights [BLH] T All converted into Cartesian coordinates [xyz] T In the form of selecting an origin [x0y0z0] T After that, the navigation coordinates of a point are calculated as follows:

[0074]

[0075] Where [ΔxΔyΔz] T =[xyz] T -[x0y0z0] T .

[0076] The IMU attitude obtained by the GNSS / INS combination algorithm is relative to the navigation coordinate system, so the IMU position (navigation system coordinates) and attitude can form a pose sequence. You can Convert to IMU coordinate system I and get the inverse I coordinate system

[0077]

[0078] After preselection and conversion, the coordinates of the two coordinate systems at time k are associated and

[0079]

[0080]

[0081] The weight of each equation is Where exp(·) represents the exponential function and F is the scaling factor. The above formula can be simplified as Then the K moments can be combined to obtain the following system of equations:

[0082]

[0083] External Reference Solve via weighted least squares:

[0084]

[0085] When solving, multiple iterations are performed, and the residual is eliminated in each iteration. Larger items to increase The estimation accuracy.

[0086] In the actual implementation process, the embodiment of the present application first selects the synchronization moment of the point cloud sequence of the three angle inversions during data processing, and then evaluates the result by aligning the coordinates of the angle inversions in the IMU coordinate system and the millimeter wave radar coordinate system using the estimated external parameters to evaluate the alignment effect. 20 rounds of iterative calculations are set, and observations with large residuals are eliminated during the iteration process. Figure 4 (a) and Figure 4 (b) shows the angular inverse coordinate alignment results after the 1st and 20th iterations, respectively. It can be seen that with the increase of iterations, better alignment effect can be achieved, and outliers can be removed by limiting the residual.

[0087] Table 1 shows the calibrated millimeter-wave radar-IMU external parameter results, external parameter statistics std, and aligned reprojection errors. The results show that the estimated millimeter-wave radar-IMU heading deviation angle error is 0.07 degrees, and the translation difference is 0.1m, which shows that the embodiment of the present application has a high calibration accuracy. The reprojection error is 0.2m, which is consistent with the ranging accuracy level of the millimeter-wave radar.

[0088] Among them, Table 1 is the statistical analysis table of millimeter wave radar-IMU external parameters.

[0089] Table 1

[0090]

[0091] In summary, combined Figure 5 As shown, the embodiment of the present application proposes a method for calibrating the external parameters of a moving carrier millimeter-wave radar-IMU based on angle reflection under the assistance of GNSS. In this method, three corner reflectors obtain high-precision GNSS coordinates through GNSS RTK, and the millimeter-wave radar, IMU, and GNSS are synchronously turned on during the movement of the carrier. The distance from the corner reflector to the carrier is dynamically calculated through the GNSS coordinate sequence of the carrier and the GNSS coordinates of the corner reflector, so as to select the angle reflection point cloud coordinates; then, the high-precision posture of the IMU is calculated through the GNSS / INS combined navigation algorithm, and the GNSS coordinates of the corner reflector are converted to the IMU coordinate system to obtain the position of the angle reflection in the IMU coordinate system; finally, the point cloud coordinates of the angle reflection are associated with the coordinates in the IMU coordinate system, and the external parameters of the millimeter-wave radar-IMU are solved by the iterative least squares method, and the gross error data are gradually eliminated during the calculation process to improve the accuracy. As a result, the limitations of the traditional calibration method in complex environments are solved, and the calibration accuracy and system robustness in dynamic environments are greatly improved. The embodiment of the present application provides a new calibration solution for the efficient fusion of millimeter-wave radar and IMU, which is suitable for various practical application scenarios, including autonomous driving, drone navigation, robots, positioning and perception of unmanned ships, etc. At the same time, this technology can effectively improve the positioning accuracy of the sensor fusion system and provide solid support for the technological development in related fields.

[0092] According to the external parameter calibration method of the millimeter-wave radar-IMU proposed in the embodiment of the present application, by obtaining the global positioning coordinates of at least one corner reflector, the global positioning coordinates of the moving carrier and the multiple initial point cloud coordinates of each corner reflector, and based on the global positioning coordinates of each corner reflector and the global positioning coordinates of the moving carrier, the target point cloud coordinates of each corner reflector are determined from the multiple initial point cloud coordinates of each corner reflector, and the global positioning coordinates of each corner reflector are converted to the IMU coordinate system to obtain the IMU coordinates of each corner reflector, the target point cloud coordinates of each corner reflector and the IMU coordinates of each corner reflector are coordinate-associated, and the external parameters of the millimeter-wave radar-IMU are obtained based on the iterative least squares method. Thus, the problem of insufficient accuracy and robustness in the calibration of the millimeter-wave radar-IMU in complex environments is solved, and the calibration accuracy and system robustness in dynamic environments are greatly improved.

[0093] Next, the external parameter calibration device of the millimeter-wave radar-IMU proposed in accordance with the embodiment of the present application is described with reference to the accompanying drawings.

[0094] Figure 6 It is a block diagram of an external parameter calibration device of a millimeter-wave radar-IMU according to an embodiment of the present application.

[0095] like Figure 6 As shown, the millimeter wave radar-IMU external parameter calibration device 10 includes: an acquisition module 100, a determination module 200 and an association module 300.

[0096] The acquisition module 100 is used to acquire the global positioning coordinates of at least one corner reflector, the global positioning coordinates of the moving carrier, and a plurality of initial point cloud coordinates of each corner reflector.

[0097] The determination module 200 is used to determine the target point cloud coordinates of each corner reflector from a plurality of initial point cloud coordinates of each corner reflector based on the global positioning coordinates of each corner reflector and the global positioning coordinates of the moving carrier.

[0098] The association module 300 is used to convert the global positioning coordinates of each corner reflector into the IMU coordinate system, obtain the IMU coordinates of each corner reflector, coordinately associate the target point cloud coordinates of each corner reflector with the IMU coordinates of each corner reflector, and obtain the external parameters of the millimeter wave radar-IMU based on the iterative least squares method.

[0099] Optionally, in some embodiments, the determination module 200 includes: a first determination unit and a second determination unit.

[0100] The first determining unit is used to determine a reference distance between each corner reflector and the moving carrier according to the global positioning coordinates of each corner reflector and the global positioning coordinates of the moving carrier.

[0101] The second determining unit is used to determine the target point cloud coordinates of each corner reflector from the multiple initial point cloud coordinates of each corner reflector according to the reference distance.

[0102] Optionally, in some embodiments, the first determining unit includes: a calculating subunit.

[0103] The calculation subunit is used to determine the reference distance between each corner reflector and the moving carrier based on a preset distance calculation formula according to the global positioning coordinates of each corner reflector and the global positioning coordinates of the moving carrier, wherein the preset distance calculation formula is:

[0104]

[0105] Among them, D IR,k is the reference distance, is the global positioning coordinate of the i-th reflector, is the global positioning coordinates of the moving carrier.

[0106] Optionally, in some embodiments, the association module 300 includes: a first generation unit, a switching unit and a second generation unit.

[0107] Among them, the first generation unit is used to obtain the IMU posture sequence based on a preset GNSS / INS combination algorithm.

[0108] The switching unit is used to convert the global positioning coordinates of each corner reflector into the navigation coordinate system to obtain the navigation coordinate system coordinates of each corner reflector.

[0109] The second generating unit is used to obtain the IMU coordinates of each corner reflector according to the posture sequence of the IMU and the navigation coordinate system coordinates of each corner reflector.

[0110] It should be noted that the above explanation of the embodiment of the external parameter calibration method of the millimeter-wave radar-IMU is also applicable to the external parameter calibration device of the millimeter-wave radar-IMU of this embodiment, and will not be repeated here.

[0111] According to the external parameter calibration device of the millimeter-wave radar-IMU proposed in the embodiment of the present application, by obtaining the global positioning coordinates of at least one corner reflector, the global positioning coordinates of the moving carrier and the multiple initial point cloud coordinates of each corner reflector, and based on the global positioning coordinates of each corner reflector and the global positioning coordinates of the moving carrier, the target point cloud coordinates of each corner reflector are determined from the multiple initial point cloud coordinates of each corner reflector, and the global positioning coordinates of each corner reflector are converted to the IMU coordinate system to obtain the IMU coordinates of each corner reflector, the target point cloud coordinates of each corner reflector and the IMU coordinates of each corner reflector are coordinate-associated, and the external parameters of the millimeter-wave radar-IMU are obtained based on the iterative least squares method. Thus, the problem of insufficient accuracy and robustness in the calibration of the millimeter-wave radar-IMU in a complex environment is solved, and the calibration accuracy and system robustness in a dynamic environment are greatly improved.

[0112] Figure 7 A schematic diagram of the structure of the device provided in the embodiment of the present application. The device may include:

[0113] A memory 701 , a processor 702 , and a computer program stored in the memory 701 and executable on the processor 702 .

[0114] When the processor 702 executes the program, the millimeter wave radar-IMU external parameter calibration method provided in the above embodiment is implemented.

[0115] Furthermore, the device also includes:

[0116] The communication interface 703 is used for communication between the memory 701 and the processor 702 .

[0117] The memory 701 is used to store computer programs that can be executed on the processor 702 .

[0118] The memory 701 may include a high-speed RAM (Random Access Memory) memory, and may also include a non-volatile memory, such as at least one disk memory.

[0119] If the memory 701, the processor 702 and the communication interface 703 are implemented independently, the communication interface 703, the memory 701 and the processor 702 can be connected to each other through a bus and communicate with each other. The bus can be an ISA (Industry Standard Architecture) bus, a PCI (Peripheral Component Interconnect) bus or an EISA (Extended Industry Standard Architecture) bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 7 Only one thick line is used in the diagram, but this does not mean that there is only one bus or only one type of bus.

[0120] Optionally, in a specific implementation, if the memory 701, the processor 702 and the communication interface 703 are integrated on a chip, the memory 701, the processor 702 and the communication interface 703 can communicate with each other through an internal interface.

[0121] The processor 702 may be a CPU (Central Processing Unit), or an ASIC (Application Specific Integrated Circuit), or one or more integrated circuits configured to implement the embodiments of the present application.

[0122] An embodiment of the present application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the above-mentioned millimeter-wave radar-IMU external parameter calibration method.

[0123] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms are not necessarily directed to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0124] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0125] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or more executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present application belong.

[0126] It should be understood that the various parts of the present application can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiment, the N steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array, a field programmable gate array, etc.

[0127] A person skilled in the art may understand that all or part of the steps in the method for implementing the above-mentioned embodiment may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

[0128] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A method for calibrating external parameters of a millimeter wave radar-IMU, characterized in that: The following steps are involved: Acquire the global positioning coordinates of at least one corner reflector, the global positioning coordinates of the moving carrier, and a plurality of initial point cloud coordinates of each corner reflector; Based on the global positioning coordinates of each corner reflector and the global positioning coordinates of the moving carrier, determining the target point cloud coordinates of each corner reflector from the multiple initial point cloud coordinates of each corner reflector; The global positioning coordinates of each corner reflector are converted to the IMU coordinate system to obtain the IMU coordinates of each corner reflector, the target point cloud coordinates of each corner reflector and the IMU coordinates of each corner reflector are coordinate-associated, and the external parameters of the millimeter-wave radar-IMU are obtained based on the iterative least squares method.

2. The method according to claim 1, characterized in that The step of determining the point cloud coordinates of each corner reflector from a plurality of initial point cloud coordinates of each corner reflector based on the global positioning coordinates of each corner reflector and the global positioning coordinates of the moving carrier comprises: Determine a reference distance between each corner reflector and the moving carrier according to the global positioning coordinates of each corner reflector and the global positioning coordinates of the moving carrier; The target point cloud coordinates of each corner reflector are determined from the multiple initial point cloud coordinates of each corner reflector according to the reference distance.

3. The method according to claim 2, characterized in that The step of determining a reference distance between each corner reflector and the moving carrier according to the global positioning coordinates of each corner reflector and the global positioning coordinates of the moving carrier comprises: Based on a preset distance calculation formula, a reference distance between each corner reflector and the moving carrier is determined according to the global positioning coordinates of each corner reflector and the global positioning coordinates of the moving carrier, wherein the preset distance calculation formula is: Among them, D IR,k is the reference distance, is the global positioning coordinate of the i-th reflector, is the global positioning coordinates of the moving carrier.

4. The method according to claim 1, characterized in that: The method of converting the global positioning coordinates of each corner reflector into the IMU coordinate system to obtain the IMU coordinates of each corner reflector includes: Get the IMU pose sequence based on the preset GNSS / INS combination algorithm; Convert the global positioning coordinates of each corner reflector into a navigation coordinate system to obtain the navigation coordinate system coordinates of each corner reflector; The IMU coordinates of each corner reflector are obtained according to the posture sequence of the IMU and the navigation coordinate system coordinates of each corner reflector.

5. A millimeter wave radar-IMU external parameter calibration device, characterized in that: include: An acquisition module, used to acquire the global positioning coordinates of at least one corner reflector, the global positioning coordinates of the motion carrier, and a plurality of initial point cloud coordinates of each corner reflector; A determination module, configured to determine the target point cloud coordinates of each corner reflector from a plurality of initial point cloud coordinates of each corner reflector based on the global positioning coordinates of each corner reflector and the global positioning coordinates of the moving carrier; The association module is used to convert the global positioning coordinates of each corner reflector into the IMU coordinate system to obtain the IMU coordinates of each corner reflector, coordinately associate the target point cloud coordinates of each corner reflector with the IMU coordinates of each corner reflector, and solve the external parameters of the millimeter wave radar-IMU based on the iterative least squares method.

6. The device according to claim 5, characterized in that The determining module comprises: A first determining unit, configured to determine a reference distance between each corner reflector and the moving carrier according to the global positioning coordinates of each corner reflector and the global positioning coordinates of the moving carrier; The second determining unit is used to determine the target point cloud coordinates of each corner reflector from the multiple initial point cloud coordinates of each corner reflector according to the reference distance.

7. The device according to claim 6, characterized in that The first determining unit includes: The calculation subunit is used to determine the reference distance between each corner reflector and the moving carrier according to the global positioning coordinates of each corner reflector and the global positioning coordinates of the moving carrier based on a preset distance calculation formula, wherein the preset distance calculation formula is: Among them, D IR,k is the reference distance, is the global positioning coordinate of the i-th reflector, is the global positioning coordinates of the moving carrier.

8. The device according to claim 5, characterized in that The association module comprises: A first generating unit, used for obtaining a pose sequence of the IMU based on a preset GNSS / INS combination algorithm; A switching unit, used for converting the global positioning coordinates of each corner reflector into a navigation coordinate system to obtain the navigation coordinate system coordinates of each corner reflector; The second generating unit is used to obtain the IMU coordinates of each corner reflector according to the posture sequence of the IMU and the navigation coordinate system coordinates of each corner reflector.

9. An electronic device, characterized in that: include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the external parameter calibration method of the millimeter-wave radar-IMU as described in any one of claims 1 to 4.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: The program is executed by a processor to implement the external parameter calibration method of the millimeter wave radar-IMU as described in any one of claims 1 to 4.

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