Vehicle-mounted millimeter wave radar external parameter calibration method and device, electronic equipment and storage medium

Abstract

The application discloses a kind of vehicle-mounted millimeter wave radar's external parameter calibration method, device and electronic equipment, storage medium, wherein the method includes respectively collecting multiple groups of the first radar point cloud data of at least one main millimeter wave radar and preset calibration device and the second radar point cloud data of multiple slave millimeter wave radars and preset calibration device;Based on the fixed distance, according to the second radar point cloud data, the first radar point cloud data, determine the relative position relationship between the at least one main millimeter wave radar and multiple slave millimeter wave radars;The relative position relationship is used as the external parameter calibration result of millimeter wave radar joint calibration. Directly calibrate the external parameter between millimeter wave radar by the application, not only reduce the dependence on equipment, installation location and operation, and guarantee the optimal result.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of automatic driving sensor calibration, and in particular to a method and device for calibrating external parameters of a vehicle-mounted millimeter wave radar, an electronic device and a storage medium. BACKGROUND

[0002] The millimeter wave radar has the characteristics of wide frequency band, easy realization of narrow beam, high resolution and difficulty in being disturbed. The millimeter wave radar is a high-precision sensor for measuring the relative distance, relative speed and relative direction of a measured object and is applied to the fields of automobile electronics, unmanned aerial vehicles and intelligent transportation.

[0003] In the related art, for joint calibration between millimeter wave radars, a common method currently uses the conversion relationship of an intermediate sensor or device. For example, in some methods, a target simulator is arranged according to the normal direction of the vertical plane in which the millimeter wave radar is located, and the calibration of two radio frequency units can be completed according to the first and second angles. For another example, in some other methods, the joint calibration is completed by obtaining the vehicle motion trajectory through a GPS and / or inertial navigation system and each millimeter wave radar, and the angle correction coefficients of each millimeter wave radar obtained through the joint calibration are written into the corresponding millimeter wave radars to realize the calibration of each millimeter wave radar.

[0004] Since the relationship between the millimeter wave and other sensors is usually calculated, and then the external parameters between the millimeter waves are indirectly calculated, the indirect conversion increases the error, and the cost is high due to the limitation of the device. SUMMARY

[0005] The application provides a method and device for calibrating external parameters of a vehicle-mounted millimeter wave radar, and an electronic device and a storage medium, to directly calibrate the external parameters between millimeter wave radars.

[0006] The application adopts the following technical solution: in a first aspect, the application provides a method for calibrating external parameters of a vehicle-mounted millimeter wave radar, which is applied to joint calibration between at least one master millimeter wave radar and multiple slave millimeter wave radars. The method comprises the following steps: a plurality of groups of first radar point cloud data of the at least one master millimeter wave radar and a preset calibration device and second radar point cloud data of the multiple slave millimeter wave radars and the preset calibration device are respectively collected, the preset calibration device comprises multiple corner reflectors, each target corner reflector in the multiple corner reflectors is one-to-one matched with the at least one master millimeter wave radar and the multiple slave millimeter wave radars, and the target corner reflectors have a fixed distance therebetween; based on the fixed distance, the relative position relationship between the at least one master millimeter wave radar and the multiple slave millimeter wave radars is determined according to the second radar point cloud data and the first radar point cloud data; and the relative position relationship is taken as the external parameter calibration result of the millimeter wave radar joint calibration.

[0007] In a second aspect, the embodiments of the present application also provide a device for calibrating external parameters of a vehicle-mounted millimeter wave radar, which is applied to joint calibration between at least one master millimeter wave radar and multiple slave millimeter wave radars, and comprises: a radar point cloud data acquisition module, configured to acquire multiple sets of first radar point cloud data of the at least one master millimeter wave radar and a preset calibration device and multiple sets of second radar point cloud data of the multiple slave millimeter wave radars and the preset calibration device, respectively, wherein the preset calibration device comprises multiple corner cubes, each target corner cube in the multiple corner cubes is matched one-to-one with the at least one master millimeter wave radar and the multiple slave millimeter wave radars, and each pair of target corner cubes has a fixed distance; a radar external parameter calculation module, configured to determine a relative position relationship between the at least one master millimeter wave radar and the multiple slave millimeter wave radars based on the fixed distance and according to the second radar point cloud data and the first radar point cloud data; and a radar external parameter output module, configured to output the relative position relationship as an external parameter calibration result of millimeter wave radar joint calibration.

[0008] In a third aspect, the embodiments of the present application also provide an electronic device, comprising: a processor; and a memory arranged to store computer executable instructions that, when executed, cause the processor to perform the above method.

[0009] In a fourth aspect, the embodiments of the present application also provide a computer readable storage medium storing one or more programs, which, when executed by an electronic device comprising multiple application programs, cause the electronic device to perform the above method.

[0010] The above at least one technical scheme adopted by the embodiments of the present application can achieve the following beneficial effects:

[0011] By acquiring multiple sets of first radar point cloud data of the at least one master millimeter wave radar and a preset calibration device and multiple sets of second radar point cloud data of the multiple slave millimeter wave radars and the preset calibration device, respectively, and determining a relative position relationship between the at least one master millimeter wave radar and the multiple slave millimeter wave radars according to the second radar point cloud data and the first radar point cloud data, joint calibration between the master millimeter wave radar and the multiple slave millimeter wave radars is directly performed, and an external parameter calibration result of millimeter wave radar joint calibration is obtained. BRIEF DESCRIPTION OF DRAWINGS

[0012] The accompanying drawings, which are included to provide a further understanding of the present application, constitute a part of the present application and illustrate the illustrative embodiments of the present application and their description serve to explain the present application, but do not constitute improper limitations on the present application. In the drawings:

[0013] Figure 1A flowchart of a vehicle-mounted millimeter wave radar external parameter calibration method in an embodiment of the present application is shown.

[0014] Figure 2 A structural diagram of a vehicle-mounted millimeter wave radar external parameter calibration device in an embodiment of the present application is shown.

[0015] Figure 3 A placement position diagram of a calibration device in a vehicle-mounted millimeter wave radar external parameter calibration method in an embodiment of the present application is shown.

[0016] Figure 4 A placement position diagram of a calibration device in a vehicle-mounted millimeter wave radar external parameter calibration method in a preferred embodiment of the present application is shown.

[0017] Figure 5 A placement position diagram in a vehicle-mounted millimeter wave radar external parameter calibration method in an embodiment of the present application is shown.

[0018] Figure 6 An implementation flowchart of a vehicle-mounted millimeter wave radar external parameter calibration method in an embodiment of the present application is shown.

[0019] Figure 7 A structural diagram of an electronic device in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0020] To make the objectives, technical solutions, and advantages of the present application clearer, the following will describe the technical solutions of the present application in conjunction with specific embodiments of the present application and corresponding drawings. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0021] The following will describe the technical solutions provided by the embodiments of the present application in conjunction with the drawings.

[0022] The embodiments of the present application provide a vehicle-mounted millimeter wave radar external parameter calibration method, as shown in Figure 1 A flowchart of a vehicle-mounted millimeter wave radar external parameter calibration method in an embodiment of the present application is shown. The method includes at least the following steps S110 to S130:

[0023] Step S110: respectively collecting a plurality of sets of first radar point cloud data of the at least one master millimeter wave radar and a preset calibration device and second radar point cloud data of the plurality of slave millimeter wave radars and the preset calibration device, wherein the preset calibration device includes a plurality of corner reflectors, each target corner reflector in the plurality of corner reflectors is one-to-one matched with the at least one master millimeter wave radar and the plurality of slave millimeter wave radars, and each two target corner reflectors has a fixed distance.

[0024] The main millimeter wave radar can be selected from any one of the vehicle-mounted millimeter wave radars, and the others are slave millimeter wave radars. The method in the application is applied to joint calibration between at least one main millimeter wave radar and multiple slave millimeter wave radars.

[0025] First radar point cloud data of the at least one main millimeter wave radar and a preset calibration device and second radar point cloud data of the multiple slave millimeter wave radars and the preset calibration device are collected, and multiple groups of radar point cloud data are obtained by adjusting the positions and angles between the main millimeter wave radars and the slave millimeter wave radars.

[0026] It should be noted that the preset calibration device includes multiple corner cubes, and each target corner cube in the multiple corner cubes is one-to-one matched with the at least one main millimeter wave radar and the multiple slave millimeter wave radars. That is, there is a corresponding corner cube for each millimeter wave radar to match, and of course the same corner cube can correspond to multiple millimeter wave radars.

[0027] Meanwhile, in order to better calculate, the fixed distances exist between the target corner cubes.

[0028] In step S120, based on the fixed distances, the relative position relationship between the at least one main millimeter wave radar and the multiple slave millimeter wave radars is determined according to the second radar point cloud data and the first radar point cloud data.

[0029] Based on the fixed distances, the relative position relationship between the at least one main millimeter wave radar and the multiple slave millimeter wave radars is determined according to the second radar point cloud data and the first radar point cloud data.

[0030] It should be noted that the second radar point cloud data and the first radar point cloud data herein include multiple groups of collected point cloud data.

[0031] In step S130, the relative position relationship is taken as an external parameter calibration result of millimeter wave radar joint calibration.

[0032] That is, the process of solving the corresponding position relationship is the process of calibration, so that the relative position relationship is taken as an external parameter calibration result of millimeter wave radar joint calibration. It should be noted that the relative position relationship of the (main) millimeter wave radar and the (slave) millimeter wave radar includes rotation and translation.

[0033] In an embodiment of the present application, the determining the relative position relationship between the at least one master millimeter wave radar and the plurality of slave millimeter wave radars based on the fixed distance and according to the second radar point cloud data and the first radar point cloud data further comprises: projecting the point cloud data of the slave millimeter wave radars onto the master millimeter wave radar and calculating the distance error after the reverse projection, wherein the distance error comprises an average reverse projection error; and if the average reverse projection error is greater than the radar ranging accuracy threshold value, re-collecting the radar point cloud data until the average error is not greater than the radar ranging accuracy threshold value.

[0034] In implementation, in order to better verify the error of the external parameter calibration result, the point of the slave radar is projected onto the master radar, and the distance error after the reverse projection is calculated. It should be noted that the distance error comprises an average reverse projection error.

[0035] The error is represented as an average reverse projection error:

[0036]

[0037] If the average reverse projection error is greater than a threshold value Te set for the average error, the steps of re-collecting and calculating are repeated until the average error is less than or equal to Te.

[0038] In some embodiments, the Te can be determined according to the radar ranging accuracy, and is generally about 0.5m-0.6m.

[0039] In an embodiment of the present application, the taking the relative position relationship as the external parameter calibration result of the millimeter wave radar joint calibration comprises: outputting the external parameter calibration result of the millimeter wave radar joint calibration and the average reverse projection error.

[0040] In implementation, the outputting of the external parameter calibration result of the millimeter wave radar joint calibration and the average reverse projection error inputs a plurality of groups of radar point cloud data. Thus, the dependence on equipment, installation position and operation is reduced, and the optimal result is ensured.

[0041] Preferably, the method in the embodiment of the present application is used in a plurality of automatic driving vehicles, and the calibration result is directly outputted after more than 100 times of calibration verification, and the success rate reaches 99%.

[0042] In an embodiment of the present application, the determining, based on the fixed distance, the relative position relationship between the at least one master millimeter wave radar and the plurality of slave millimeter wave radars according to the second radar point cloud data and the first radar point cloud data comprises: constructing a radar optimization model based on the fixed distance; inputting the second radar point cloud data and the first radar point cloud data into the radar optimization model, and outputting the relative position relationship between the at least one master millimeter wave radar and the plurality of slave millimeter wave radars, wherein the relative position relationship at least comprises one of rotation and translation.

[0043] In specific implementation, the radar optimization model based on the fixed distance is a radar optimization equation based on distance constraint, and the external parameter of the radar is solved. The optimization equation is as follows:

[0044] min(d-||T*Ps-Pm||2),

[0045] wherein d is the distance between the target corner reflectors (each two target corner reflectors have a fixed distance), T is the external parameter to be solved, Ps is the radar point cloud data of the slave device, and Pm is the radar point cloud data of the master device.

[0046] Thus, the second radar point cloud data Ps and the first radar point cloud data Pm are input into the radar optimization model, and the relative position relationship between the at least one master millimeter wave radar and the plurality of slave millimeter wave radars is output.

[0047] In an embodiment of the present application, the collecting a plurality of groups of the first radar point cloud data of the at least one master millimeter wave radar and the second radar point cloud data of the plurality of slave millimeter wave radars with respect to a preset calibration device respectively, wherein the preset calibration device comprises a plurality of corner reflectors, each target corner reflector in the plurality of corner reflectors is one-to-one matched with the at least one master millimeter wave radar and the plurality of slave millimeter wave radars, and each two target corner reflectors have a fixed distance therebetween, comprises: placing the preset calibration device in the FOV range of the at least one master millimeter wave radar and the plurality of slave millimeter wave radars, and synchronously collecting the first radar point cloud data and the second radar point cloud data; and adjusting the position of the preset calibration device and / or the radar RCS, so that each target corner reflector in the plurality of corner reflectors is one-to-one matched with the at least one master millimeter wave radar and the plurality of slave millimeter wave radars.

[0048] In specific implementation, for the preset calibration device, the preset calibration device needs to be placed in the FOV range of the at least one master millimeter wave radar and the plurality of slave millimeter wave radars, and the first radar point cloud data and the second radar point cloud data are synchronously collected.

[0049] For example, the master and slave angle reflectors, with their preset calibration devices positioned within the FOV (field of view) of the master and slave millimeter-wave radars respectively, have their openings facing the beam directions of the master and slave millimeter-wave radars. Simultaneously, point cloud data from both master and slave radars are acquired.

[0050] By adjusting the position of the preset calibration device and / or the radar RCS, each target angle reflection in the plurality of angle reflections is matched one-to-one with the at least one main millimeter-wave radar and the plurality of slave millimeter-wave radars.

[0051] For example, based on angular anti-movement position constraints and RCS radar cross section thresholds, redundant point cloud data can be deleted, while retaining one-to-one matching point cloud data.

[0052] In one embodiment of this application, such as Figure 5 As shown, the method further includes: the at least one main millimeter-wave radar and the plurality of slave millimeter-wave radars are linked by a rigid body, and when the at least one main millimeter-wave radar is adjusted, the plurality of slave millimeter-wave radars are adjusted accordingly, and the direction of the angular anti-opening is directly opposite to the beam direction of the main millimeter-wave radar and the slave millimeter-wave radar.

[0053] In specific implementation, such as Figure 3 , Figure 4 As shown, the main and secondary reflectors are placed with their openings facing the millimeter-wave radar, regardless of whether the main and secondary radars share a common field of view (FOV). For example, the main and secondary reflectors are fixed with low-reflection materials (such as wooden supports), and multiple reflector supports are connected by horizontally rotating rods at fixed intervals to ensure that the distance between the main and secondary reflectors is fixed, they are placed stably on the ground, and can be moved mechanically or manually.

[0054] In one embodiment of this application, the method further includes: when there is no common FOV or there is a common FOV between the at least one primary millimeter-wave radar and the plurality of secondary millimeter-wave radars, each target angle is matched one-to-one with the at least one primary millimeter-wave radar and the plurality of secondary millimeter-wave radars.

[0055] In practice, regardless of whether there is a common field of view (FOV) between the at least one main millimeter-wave radar and the multiple slave millimeter-wave radars, each target angle is matched one-to-one with the at least one main millimeter-wave radar and the multiple slave millimeter-wave radars.

[0056] like Figure 6 As shown in the schematic diagram, the implementation flow of the external parameter calibration method for vehicle-mounted millimeter-wave radar in this application embodiment includes the following steps:

[0057] Step S610, place the calibration device, and the master and slave angle inverses are respectively located within the FOV range of the master and slave radars.

[0058] The master and slave angle inverses are respectively placed with their openings directly facing the directions of the millimeter wave radars, and are not limited to whether the master and slave radars have a common FOV. The master and slave angle inverses are respectively located within the FOV range of the master and slave millimeter wave radars, and the directions of the openings of the master and slave angle inverses are respectively directly facing the directions of the beams of the master and slave millimeter wave radars.

[0059] Step S620, synchronously collect radar point cloud data within the FOV range of the master and slave radars.

[0060] Step S630, complete one-to-one matching according to the position constraint.

[0061] Synchronously collect the master and slave radar point cloud data. According to the angle inverse movement position constraint and the RCS threshold, delete the redundant point cloud, and retain the one-to-one matched point cloud data.

[0062] Step S640, move the calibration device, and collect more than 20 groups of data.

[0063] Repeat the above steps to collect more than N groups of data (N>20).

[0064] Step S650, construct an optimization equation of a radar distance constraint, and solve the radar external parameter.

[0065] After the collection is completed, an optimization equation of a radar based on a distance constraint is constructed, and a radar external parameter (the relative position of the radar and the radar, including rotation and translation) is solved. The optimization equation is as follows:

[0066] min(d-||T*Ps-Pm||2), where d is the distance between the angle inverses, T is the external parameter to be solved, Ps is the radar point cloud data of the slave device, and Pm is the radar point cloud data of the master device.

[0067] Step S660, verify the re-projection result, and if the projection error is greater than Te, repeat the above steps.

[0068] Project the slave radar point onto the master radar, and calculate the distance error after the re-projection. The average re-projection calculation equation is as follows:

[0069] error is the average re-projection error.

[0070] If the average re-projection error>Te (Te is a threshold value set by a user), repeat the steps. Until the average error is less than or equal to Te (Te is generally about 0.5 m according to the radar ranging accuracy).

[0071] Step S670, output the calibration result and the re-projection error.

[0072] Output radar extrinsic parameters and average back-projection error.

[0073] The application also provides a vehicle-mounted millimeter wave radar extrinsic parameter calibration device 200, as shown in the structural schematic diagram of the vehicle-mounted millimeter wave radar extrinsic parameter calibration device in the application, the vehicle-mounted millimeter wave radar extrinsic parameter calibration device 200 at least comprises: a radar point cloud data acquisition module 210, a radar extrinsic parameter calculation module 220, a radar extrinsic parameter output module 230, wherein: Figure 2

[0074] In an embodiment of the application, the radar point cloud data acquisition module 210 is specifically configured to: the master millimeter wave radar can be selected from any one of the vehicle-mounted millimeter wave radars, and the others are slave millimeter wave radars. The method in the application is applied to joint calibration between at least one master millimeter wave radar and multiple slave millimeter wave radars.

[0075] The first radar point cloud data of the at least one master millimeter wave radar and the preset calibration device and the second radar point cloud data of the multiple slave millimeter wave radars and the preset calibration device are acquired, and multiple groups of radar point cloud data are obtained by adjusting the positions and angles between the master millimeter wave radars and the slave millimeter wave radars.

[0076] It should be noted that the preset calibration device comprises multiple corner reflectors, and each target corner reflector in the multiple corner reflectors is one-to-one matched with the at least one master millimeter wave radar and the multiple slave millimeter wave radars. That is to say, for each millimeter wave radar, there is a corresponding corner reflector for matching, and of course the same corner reflector can correspond to multiple millimeter wave radars.

[0077] Meanwhile, in order to better calculate, the fixed distance is provided between each two target corner reflectors.

[0078] In an embodiment of the application, the radar extrinsic parameter calculation module 220 is specifically configured to: based on the fixed distance, determining the relative position relationship between the at least one master millimeter wave radar and the multiple slave millimeter wave radars according to the second radar point cloud data and the first radar point cloud data.

[0079] It should be noted that the second radar point cloud data and the first radar point cloud data herein include multiple groups of respectively acquired point cloud data.

[0080] In an embodiment of the application, the radar extrinsic parameter output module 230 is specifically configured to: the process of solving the corresponding position relationship is the calibration process, so that the relative position relationship is taken as the extrinsic parameter calibration result of the millimeter wave radar joint calibration. It should be noted that the relative position relationship of the (master) millimeter wave radar and the (slave) millimeter wave radar includes rotation and translation.​

[0081] It can be understood that the above-mentioned external parameter calibration device of the vehicle-mounted millimeter wave radar can realize each step of the external parameter calibration method of the vehicle-mounted millimeter wave radar provided in the foregoing embodiments, and the related explanations about the external parameter calibration method of the vehicle-mounted millimeter wave radar are all applicable to the external parameter calibration device of the vehicle-mounted millimeter wave radar, which will not be repeated here.

[0082] Figure 7 is a structural schematic diagram of an electronic device according to an embodiment of the present application. Please refer to Figure 7 At the hardware level, the electronic device includes a processor, and optionally further includes an internal bus, a network interface, and a memory. The memory can include a memory such as a random-access memory (RAM), and can also include a non-volatile memory such as at least one disk memory. Of course, the electronic device can also include other hardware required by the business.

[0083] The processor, the network interface, and the memory can be connected to each other through the internal bus, which can be an industry standard architecture (ISA) bus, a peripheral component interconnect (PCI) bus, or an extended industry standard architecture (EISA) bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 7 In the figure, only one bidirectional arrow is used to represent the bus, but it does not mean that there is only one bus or only one type of bus.

[0084] The memory is used to store programs. Specifically, the program can include program code including computer operation instructions. The memory can include a memory and a non-volatile memory, and provide instructions and data to the processor.

[0085] The processor reads the corresponding computer program from the non-volatile memory into the memory and then runs, and forms the external parameter calibration device of the vehicle-mounted millimeter wave radar at the logical level. The processor executes the program stored in the memory, and is specifically used to perform the following operations:

[0086] Multiple sets of first radar point cloud data of at least one main millimeter-wave radar and a preset calibration device and second radar point cloud data of multiple slave millimeter-wave radars and a preset calibration device are collected respectively. The preset calibration device includes multiple angle reflectors. Each target angle reflector in the multiple angle reflectors corresponds one-to-one with the at least one main millimeter-wave radar and the multiple slave millimeter-wave radars. There is a fixed distance between each pair of target angle reflectors.

[0087] Based on the fixed distance, the relative positional relationship between the at least one main millimeter-wave radar and the multiple slave millimeter-wave radars is determined according to the second radar point cloud data and the first radar point cloud data.

[0088] The relative positional relationship is used as the external parameter calibration result of the joint calibration of millimeter-wave radar.

[0089] The above is as stated in this application. Figure 1 The method executed by the extrinsic parameter calibration device for vehicle-mounted millimeter-wave radar disclosed in the illustrated embodiment can be applied to a processor or implemented by a processor. The processor may be an integrated circuit chip with signal processing capabilities. During implementation, each step of the above method can be completed by integrated logic circuits in the processor's hardware or by instructions in software form. The processor can be a general-purpose processor, including a Central Processing Unit (CPU), a Network Processor (NP), etc.; it can also be a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field-Programmable Gate Array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. It can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of this application. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in the embodiments of this application can be directly embodied as being executed by a hardware decoding processor, or executed by a combination of hardware and software modules in the decoding processor. The software module can reside in a mature storage medium in the field, such as random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, or registers. This storage medium is located in memory, and the processor reads information from the memory and, in conjunction with its hardware, completes the steps of the above method.

[0090] The electronic device can also perform Figure 1The method executed by the external parameter calibration device of the vehicle-mounted millimeter wave radar is executed, and the external parameter calibration device of the vehicle-mounted millimeter wave radar is implemented Figure 1 The functions of the external parameter calibration device of the vehicle-mounted millimeter wave radar in the embodiment are not repeated here.

[0091] The embodiment of the application also provides a computer readable storage medium, which stores one or more programs, the one or more programs comprising instructions, which, when executed by an electronic device comprising a plurality of application programs, can enable the electronic device to perform the method of the external parameter calibration device of the vehicle-mounted millimeter wave radar Figure 1 The method executed by the external parameter calibration device of the vehicle-mounted millimeter wave radar in the embodiment is executed, and is specifically used for executing:

[0092] A plurality of groups of first radar point cloud data of the at least one master millimeter wave radar and a preset calibration device and second radar point cloud data of the plurality of slave millimeter wave radars and the preset calibration device are collected respectively, wherein the preset calibration device comprises a plurality of corner reflectors, each target corner reflector in the plurality of corner reflectors is one-to-one matched with the at least one master millimeter wave radar and the plurality of slave millimeter wave radars, and the target corner reflectors have a fixed distance therebetween;

[0093] Based on the fixed distance, the relative position relationship between the at least one master millimeter wave radar and the plurality of slave millimeter wave radars is determined according to the second radar point cloud data and the first radar point cloud data.

[0094] The relative position relationship is taken as an external parameter calibration result of millimeter wave radar joint calibration.

[0095] Those skilled in the art should understand that the embodiments of the application can be provided as a method, a system, or a computer program product. Therefore, the application can adopt a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the application can adopt a computer program product in the form of being implemented on one or more computer usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer usable program codes.

[0096] The application is described with reference to flowcharts and / or block diagrams of the method, device (system), and computer program product according to the embodiments of the application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and the combination of the flows and / or blocks in the flowcharts and / or block diagrams can be realized by computer program instructions. These computer program instructions can be provided to a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to produce a machine, so that the instructions executed by the computer or other programmable data processing devices produce a machine for realizing the functions specified in the flowcharts and / or block diagrams. Figure 1 The flow or the plurality of flows and / or blocks Figure 1an apparatus to perform each block or blocks of the flow or multiple flows and / or a function specified in the block or blocks.

[0097] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a Figure 1 an apparatus to perform each block or blocks of the flow or multiple flows and / or a function specified in the block or blocks. Figure 1 an apparatus to perform each block or blocks of the flow or multiple flows and / or a function specified in the block or blocks.

[0098] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the flow or multiple flows and / or a function specified in the block or blocks. ​ an apparatus to perform each block or blocks of the flow or multiple flows and / or a function specified in the block or blocks. ​ an apparatus to perform each block or blocks of the flow or multiple flows and / or a function specified in the block or blocks.

[0099] In a typical configuration, a computing device includes one or more processors (CPUs), input / output interfaces, network interfaces, and memory.

[0100] The memory can include non-persistent memory and / or volatile memory, such as random access memory (RAM) and / or cache memory. The memory can also include non-volatile memory, such as read-only memory (ROM), electrically programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), flash memory, or a combination of non-volatile memories. The memory is an example of computer-readable media.

[0101] Computer-readable media includes permanent and non-permanent, removable and non-removable media implemented in any method or technology for storage of information such as computer-readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically programmable read-only memory (EEPROM), flash memory or other memory technology, compact disc read-only memory (CD-ROM), digital versatile disc (DVD), or other optical storage, magnetic cassettes, magnetic tapes, magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information accessible to a computing device. According to the definition herein, computer-readable media does not include transitory media, such as modulated data signals and carrier waves.

[0102] It is also to be noted that the terms "comprising", "including", and any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "comprises a... " does not, without more constraints, exclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the recited element.

[0103] Those skilled in the art will appreciate that embodiments of the present application can be devised for a method, a system, or a computer program product. Accordingly, the present application can take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application can take the form of a computer program product on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROMs, optical storage devices, etc.) embodying computer-readable program code.

[0104] The embodiments of the present application described above are merely intended to illustrate the principles of the present application, and should not be used to limit the scope of the present application. Various modifications and changes can be made by those skilled in the art to the embodiments of the present application without departing from the spirit and scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims

1. A method for calibrating the extrinsic parameters of a vehicle-mounted millimeter-wave radar, wherein, The method for joint calibration between a master millimeter-wave radar and multiple slave millimeter-wave radars includes: Multiple sets of first radar point cloud data of at least one main millimeter-wave radar and a preset calibration device and second radar point cloud data of multiple slave millimeter-wave radars and a preset calibration device are collected respectively. The preset calibration device includes multiple angle reflectors. Each target angle reflector in the multiple angle reflectors corresponds one-to-one with the at least one main millimeter-wave radar and the multiple slave millimeter-wave radars. There is a fixed distance between each pair of target angle reflectors. Based on the fixed distance, the relative positional relationship between the at least one main millimeter-wave radar and the multiple slave millimeter-wave radars is determined according to the second radar point cloud data and the first radar point cloud data. The step of determining the relative positional relationship between the at least one primary millimeter-wave radar and multiple secondary millimeter-wave radars based on the fixed distance, according to the second radar point cloud data and the first radar point cloud data, includes: Construct a radar optimization model based on the fixed distance; The radar point cloud data of the two radars and the point cloud data of the first radar are input into the radar optimization model, and the relative positional relationship between at least one main millimeter-wave radar and multiple slave millimeter-wave radars is output, wherein the relative positional relationship includes at least one of the following: rotation and translation. Constructing a radar optimization model based on the fixed distance involves constructing a radar optimization equation based on range constraints and solving for the radar extrinsic parameters. The optimization equation is as follows: ， Where d is the distance between the angles, T is the extrinsic parameter to be solved, Ps is the radar point cloud data of the slave device, and Pm is the radar point cloud data of the master device. The radar point cloud data Ps of the second radar and the point cloud data Pm of the first radar are input into the radar optimization model, and the relative positional relationship between at least one main millimeter-wave radar and multiple slave millimeter-wave radars is output. The relative positional relationship is used as the external parameter calibration result of the joint calibration of millimeter-wave radar.

2. The method as described in claim 1, wherein, The step of determining the relative positional relationship between the at least one primary millimeter-wave radar and multiple secondary millimeter-wave radars based on the fixed distance, according to the second radar point cloud data and the first radar point cloud data, further includes: The point cloud data from the millimeter-wave radar is projected onto the main millimeter-wave radar, and the distance error after back projection is calculated, wherein the distance error includes the average back projection error. If the average back projection error is greater than the radar ranging accuracy threshold, then the radar point cloud data is reacquired until the average back projection error is no greater than the radar ranging accuracy threshold.

3. The method as described in claim 2, wherein, The step of using the relative positional relationship as the extrinsic parameter calibration result for the joint calibration of millimeter-wave radar includes: Output the external parameter calibration results of the millimeter-wave radar joint calibration and the average back projection error.

4. The method as described in claim 1, wherein, The process involves collecting first radar point cloud data from at least one main millimeter-wave radar and a preset calibration device, as well as second radar point cloud data from multiple slave millimeter-wave radars and the preset calibration device. The preset calibration device includes multiple angle reflectors, each target angle reflector in which a one-to-one correspondence is established between the at least one main millimeter-wave radar and the multiple slave millimeter-wave radars. A fixed distance exists between each pair of target angle reflectors. The preset calibration device is placed within the FOV range of at least one main millimeter-wave radar and the plurality of slave millimeter-wave radars, and the first radar point cloud data and the second radar point cloud data are collected synchronously. By adjusting the position of the preset calibration device and / or the radar RCS, each target angle reflection in the plurality of angle reflections is matched one-to-one with the at least one main millimeter-wave radar and the plurality of slave millimeter-wave radars.

5. The method as described in claim 1, wherein, Also includes: The at least one primary millimeter-wave radar and the plurality of secondary millimeter-wave radars are linked by a rigid body. When the at least one primary millimeter-wave radar is adjusted, the plurality of secondary millimeter-wave radars are adjusted accordingly. Furthermore, the direction of the angle-reflecting opening is directly opposite to the beam direction of the primary millimeter-wave radar and the secondary millimeter-wave radar.

6. The method of claim 5, wherein, Also includes: In the case where there is no common FOV or there is no common FOV between the at least one main millimeter-wave radar and the plurality of slave millimeter-wave radars, each target angle is matched one-to-one with the at least one main millimeter-wave radar and the plurality of slave millimeter-wave radars.

7. An external parameter calibration device for a vehicle-mounted millimeter-wave radar, wherein, The apparatus for joint calibration between a master millimeter-wave radar and multiple slave millimeter-wave radars includes: The radar point cloud data acquisition module is used to acquire first radar point cloud data of the at least one main millimeter-wave radar and the preset calibration device, as well as second radar point cloud data of the multiple slave millimeter-wave radars and the preset calibration device. The preset calibration device includes multiple angle reflectors, and each target angle reflector in the multiple angle reflectors corresponds one-to-one with the at least one main millimeter-wave radar and the multiple slave millimeter-wave radars. There is a fixed distance between each pair of target angle reflectors. The radar extrinsic parameter calculation module is used to determine the relative positional relationship between the at least one primary millimeter-wave radar and multiple secondary millimeter-wave radars based on the fixed distance, according to the second radar point cloud data and the first radar point cloud data; The step of determining the relative positional relationship between the at least one primary millimeter-wave radar and multiple secondary millimeter-wave radars based on the fixed distance, according to the second radar point cloud data and the first radar point cloud data, includes: Construct a radar optimization model based on the fixed distance; The radar point cloud data of the two radars and the point cloud data of the first radar are input into the radar optimization model, and the relative positional relationship between at least one main millimeter-wave radar and multiple slave millimeter-wave radars is output, wherein the relative positional relationship includes at least one of the following: rotation and translation. Constructing a radar optimization model based on the fixed distance involves constructing a radar optimization equation based on range constraints and solving for the radar extrinsic parameters. The optimization equation is as follows: ， Where d is the distance between the angles, T is the extrinsic parameter to be solved, Ps is the radar point cloud data of the slave device, and Pm is the radar point cloud data of the master device. The radar point cloud data Ps of the second radar and the point cloud data Pm of the first radar are input into the radar optimization model, and the relative positional relationship between at least one main millimeter-wave radar and multiple slave millimeter-wave radars is output. The radar extrinsic parameter output module is used to use the relative positional relationship as the extrinsic parameter calibration result of the millimeter-wave radar joint calibration.

8. An electronic device, comprising: processor; as well as A memory configured to store computer-executable instructions, which, when executed, cause the processor to perform the method of any one of claims 1 to 6.

9. A computer-readable storage medium storing one or more programs, which, when executed by an electronic device including a plurality of applications, cause the electronic device to perform the method of any one of claims 1 to 6.

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