CN114280563A - Pulse Doppler laser radar speed and distance measurement external calibration device and method - Google Patents
Pulse Doppler laser radar speed and distance measurement external calibration device and method Download PDFInfo
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- CN114280563A CN114280563A CN202111673580.7A CN202111673580A CN114280563A CN 114280563 A CN114280563 A CN 114280563A CN 202111673580 A CN202111673580 A CN 202111673580A CN 114280563 A CN114280563 A CN 114280563A
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Abstract
The invention provides a pulse Doppler laser radar speed and distance measurement external calibration device and a method, which are characterized in that the device comprises: the device comprises a lens group, an adjusting structure module for positioning the lens group, an optical fiber attenuator, an optical fiber delay line, an optical fiber coupler and a rotary table, wherein the device is convenient to mount and erect, so that calibration is not limited by a special calibration field and a reference target object, and the external calibration device is small in size and wide in application scene. Can carry out range finding simultaneously and test the speed and mark, mark the efficiency higher.
Description
Technical Field
The invention relates to the technical field of calibration, in particular to an external calibration device and method for speed and distance measurement of a pulse Doppler laser radar.
Background
The laser radar utilizes laser and tracers such as aerosol particles or gas molecules in the atmosphere to generate scattering, and quantitative profile type measurement of atmospheric parameters is realized through various scattering mechanisms. The pulse laser radar calculates the target distance by using the flight transition time of the light pulse, and calculates the radial speed of the target relative to the laser radar by using the Doppler frequency shift of the echo light. The commonly used laser radar ranging precision calibration comprises the following steps: (1) calculating the echo delay of the target reference object reflection by using the accurately known geometrical relationship; (2) the strong reflection waveform of the light pulse on the end face of the telescope is used as zero distance calculation. The commonly used laser radar speed measurement calibration scheme comprises the following steps: (1) the laser radar is placed on a mobile platform and actually measures and calculates the motion of a relative static target object; (2) and converging the laser beam on the rotating target for actual measurement and calculation.
The inventor finds that the existing distance measurement and speed measurement calibration method has certain limitation in the actual use process. In the first method of ranging, it is difficult to select a target reference object. Particularly for long-pulse laser radars, reference objects except a plurality of range gates need to be selected to avoid influence caused by blind areas, and the requirements for selecting a calibration site and the reference objects are high; in the second method, due to strong end reflection, a received return signal has obvious saturation topping, and an error is generated by using the morphological analysis of an echo. The first method of measuring speed requires a longer calibration site and a smooth-running platform. In the second method, the convergence shape of the emitted laser needs to be adjusted, and the geometric relationship needs to be accurately adjusted, so that the relationship between the convergence efficiency and the velocity component is ensured.
Disclosure of Invention
In view of the above, to solve the above technical problems, the present invention provides an external calibration apparatus and method for speed and distance measurement of a pulse doppler laser radar.
In a first aspect, an embodiment of the present invention provides an external calibration apparatus for speed and distance measurement of a pulse doppler laser radar, including:
the optical fiber attenuator is used for adjusting the position of the lens group;
the adjusting structure module for positioning the lens group is connected with the lens group and used for adjusting the lens group to a target position, wherein when a receiving optical axis of the lens group is superposed with an optical axis of a laser beam emitted by a radar to be calibrated, the position of the lens group corresponding to the target position is the target position;
the lens group is used for enabling laser beams emitted by a radar to be calibrated to enter from the first end of the lens component and be output from the second end of the lens component after being focused by the lens component;
the first end of the optical fiber attenuator is connected with the second end of the lens assembly, the laser beam output by the second end of the lens assembly and focused by the lens assembly enters from the first end of the optical fiber attenuator, and is output by the second end of the optical fiber attenuator after being attenuated by the optical fiber attenuator;
the first end of the optical fiber delay line is connected with the second end of the optical fiber attenuator, and the attenuated laser beam output by the optical fiber attenuator is input from the first end of the optical fiber delay line, is delayed by the optical fiber delay line and is output from the second section of the optical fiber delay line; the optical fiber delay line is a single-mode optical fiber with the length L, and the single-mode optical fiber is fixed in the package in a winding mode;
the first end of the optical fiber coupler is connected with the second end of the optical fiber delay line, and the delayed laser beam output by the second end of the optical fiber delay line is coupled by the optical fiber coupler and then output by the second end of the optical fiber coupler; the optical axis of the coupled laser beam output from the second end of the optical fiber coupler and the side vertical tangent line of the rotary table form an angle of 30 degrees;
and a retro-reflection film is arranged on the side surface of the rotary table and returns the coupled laser beam output from the second end of the optical fiber coupler to the acquisition end of the radar to be calibrated according to the original path.
Preferably, the lens group includes: the device comprises a main mirror and an auxiliary mirror, wherein the main mirror and the auxiliary mirror are both reflecting mirrors;
laser beams emitted by a radar to be calibrated enter the primary mirror after entering from the first end of the lens component, are reflected by the primary mirror, enter the secondary mirror, are reflected by the secondary mirror, and are output from the second end of the lens component;
the main mirror is an off-axis parabolic reflector, and a main mirror adjusting mechanism is arranged on the main mirror and used for adjusting the position of the main mirror to realize focusing.
Preferably, the mirror surface of the primary mirror and the mirror surface of the secondary mirror are both provided with metal film layers.
Preferably, the adjusting structure module for positioning the lens group is adapted to drive the lens group to move along the corresponding direction.
Preferably, the pulse doppler laser radar speed and distance measuring external calibration device further includes:
the fixing frame is connected with the adjusting structure module for positioning the lens group, and the fixing frame is used for assisting in positioning the adjusting structure module for positioning the lens group and fixing the lens group at a target position.
Preferably, the length of the single-mode fiber corresponding to the free space path is at least twice the radial resolution of the pulsed doppler lidar.
In a second aspect, an embodiment of the present invention provides an external calibration method for speed measurement and distance measurement of a pulse doppler laser radar, which is based on using the external calibration device for speed measurement and distance measurement of a pulse doppler laser radar according to any one of the first aspect, and the method includes:
after the adjusting structure module for positioning the lens group is connected with the lens group, the lens group is adjusted to a target position by adopting the adjusting structure module for positioning the lens group; the target position is the position of the lens group when the receiving optical axis of the lens group is superposed with the optical axis of the laser beam emitted by the radar to be calibrated;
the first end of the optical fiber attenuator enters the laser beam which is output by the second end of the lens component and is focused by the lens component, and the laser beam is attenuated by the optical fiber attenuator and then is output to the optical fiber delay line by the second end of the optical fiber attenuator;
the first end of the optical fiber delay line inputs the laser beam output by the optical fiber attenuator after being attenuated, and the laser beam is output to the optical fiber coupler from the second end of the optical fiber delay line after being delayed by the optical fiber delay line; the optical fiber delay line is a single-mode optical fiber with the length L, and the single-mode optical fiber is fixed in the package in a winding mode;
the optical fiber coupler receives the delayed laser beam output by the second end of the optical fiber delay line, and the laser beam is coupled by the optical fiber coupler and then output by the second end of the optical fiber coupler;
the coupled laser beam output from the second end of the optical fiber coupler meets a back reflection film arranged on the side surface of the rotary table and returns in the original path;
the optical fiber attenuator is characterized in that the first end of the optical fiber attenuator is connected with the second end of the lens assembly, the first end of the optical fiber delay line is connected with the second end of the optical fiber attenuator, the first end of the optical fiber coupler is connected with the second end of the optical fiber delay line, the optical axis of the coupled laser beam output from the second end of the optical fiber coupler is at an angle of 30 degrees with the tangent line of the side vertical surface of the turntable.
In a third aspect, an embodiment of the present invention provides a method for calibrating a pulse doppler laser radar, where the method is based on using the device for calibrating speed and distance of the pulse doppler laser radar in the first aspect, and the method includes:
after the lens group is adjusted to a target position, generating a control instruction to control the rotary table to rotate according to a corresponding angular speed, wherein when a receiving optical axis of the lens group is superposed with an optical axis of a laser beam emitted by a radar to be calibrated, the position of the lens group corresponding to the target position is the target position;
after the turntable stably rotates, starting a pulse Doppler laser radar to emit a laser beam and collect data, determining a light pulse reflected by the pulse Doppler laser radar speed and distance measuring external calibration device and a corresponding sampling time sequence by utilizing a data calculation system of the pulse Doppler laser radar, obtaining corresponding actual distance measuring information, and generating a distance measuring calibration result based on determined theoretical distance measuring information, wherein the theoretical distance measuring information is determined based on the distance between the laser and the side vertical surface of the turntable after the laser passes through an optical fiber of the pulse Doppler laser radar speed and distance measuring external calibration device.
Preferably, the method further comprises:
calculating the measured radial Doppler frequency shift;
calculating to obtain theoretical Doppler shift according to the radial rotating speed to be measured by the theoretical rotary table and a Doppler shift calculation formula;
and generating a speed measurement calibration result based on the measured radial Doppler shift and the calculated theoretical Doppler shift.
In a fourth aspect, an embodiment of the present invention provides a computer device, including: the memory and the processor are connected with each other in a communication manner, the memory stores computer instructions, and the processor executes the computer instructions, so as to implement the pulsed doppler lidar calibration method according to any one of the third aspect.
In a fifth aspect, a non-transitory computer-readable storage medium is provided according to an embodiment of the present invention, and stores computer instructions, which when executed by a processor, implement the pulsed doppler lidar calibration method according to any of the third aspect.
The device and the method for calibrating the speed and the distance of the pulse Doppler laser radar have the following advantages:
the embodiment of the invention provides an external calibration device for measuring speed and distance of a pulse Doppler laser radar, which can measure the distance and measure the speed of the corresponding radar without specially selecting a calibration field and a reference target object. The volume is small and exquisite, erect the convenience, under the use scene restriction, can be used to under most external field environment. The distance measurement and speed measurement calibration is carried out through the delay line and the rotary table, the calibration can be carried out simultaneously, and the calibration efficiency is improved. The configuration setting of devices such as camera lens subassembly, adjustable attenuator can adjust, has improved the suitability and the practicality that range finding, speed measured, has improved range finding simultaneously, the accuracy height that tests the speed. Furthermore, the calibration performance of the external calibration device is improved. The convenient and accurate laser radar ranging and speed measuring external calibration device is provided, and the problem that an existing laser radar calibration method faces in the aspects of field and reference object selection is solved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a schematic structural diagram of an adjustment structure module according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a lens assembly according to an embodiment of the present invention;
FIG. 3 is a schematic view of a turntable mechanism provided in an embodiment of the present invention;
fig. 4 is a flowchart of a method for calibrating a pulse doppler lidar according to an embodiment of the present invention;
fig. 5 is a schematic view illustrating an installation of an external calibration device and a radar according to an embodiment of the present invention;
fig. 6 is a timing diagram of a ranging calibration according to an embodiment of the present invention;
fig. 7 is a flowchart of another pulse doppler lidar calibration method according to an embodiment of the present invention;
fig. 8 is a schematic structural diagram of a computer device according to an embodiment of the present invention.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; the two elements may be directly connected or indirectly connected through an intermediate medium, or may be communicated with each other inside the two elements, or may be wirelessly connected or wired connected. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
In addition, the technical features involved in the different embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
Although the processes described below include multiple operations that occur in a particular order, it should be clearly understood that the processes may include more or fewer operations that are performed sequentially or in parallel.
Example 1
The embodiment of the invention provides an external calibration device for speed and distance measurement of a pulse Doppler laser radar, which comprises:
the optical fiber attenuator is used for adjusting the position of the lens group;
the adjusting structure module for positioning the lens group is connected with the lens group and used for adjusting the lens group to a target position, wherein when a receiving optical axis of the lens group is superposed with an optical axis of a laser beam emitted by a radar to be calibrated, the position of the lens group corresponding to the target position is the target position;
the lens group is used for enabling laser beams emitted by a radar to be calibrated to enter from the first end of the lens component and be output from the second end of the lens component after being focused by the lens component;
the first end of the optical fiber attenuator is connected with the second end of the lens assembly, the laser beam output by the second end of the lens assembly and focused by the lens assembly enters from the first end of the optical fiber attenuator, and is output by the second end of the optical fiber attenuator after being attenuated by the optical fiber attenuator;
the first end of the optical fiber delay line is connected with the second end of the optical fiber attenuator, and the attenuated laser beam output by the optical fiber attenuator is input from the first end of the optical fiber delay line, is delayed by the optical fiber delay line and is output from the second section of the optical fiber delay line; the optical fiber delay line is a single-mode optical fiber with the length L, and the single-mode optical fiber is fixed in the package in a winding mode;
the first end of the optical fiber coupler is connected with the second end of the optical fiber delay line, and the delayed laser beam output by the second end of the optical fiber delay line is coupled by the optical fiber coupler and then output by the second end of the optical fiber coupler; the optical axis of the coupled laser beam output from the second end of the optical fiber coupler and the side vertical tangent line of the rotary table form an angle of 30 degrees;
and a retro-reflection film is arranged on the side surface of the rotary table and returns the coupled laser beam output from the second end of the optical fiber coupler to the acquisition end of the radar to be calibrated according to the original path.
In the above embodiment, specifically, the device can perform distance measurement and speed measurement calibration on the corresponding radar through the external calibration device without specially selecting a calibration site and a reference target. The volume is small and exquisite, erect the convenience, under the use scene restriction, can be used to under most external field environment. The distance measurement and speed measurement calibration is carried out through the delay line and the rotary table, the calibration can be carried out simultaneously, and the calibration efficiency is improved. The configuration setting of devices such as camera lens subassembly, adjustable attenuator can adjust, has improved the suitability and the practicality that range finding, speed measured, has improved range finding simultaneously, the accuracy height that tests the speed. Furthermore, the calibration performance of the external calibration device is improved. The convenient and accurate laser radar ranging and speed measuring external calibration device is provided, and the problem that an existing laser radar calibration method faces in the aspects of field and reference object selection is solved.
In the above embodiment, and in particular with reference to fig. 1, the device comprises an adjustment structure module 11 for positioning the lens group, for fixing the device as a whole 13 in front of the optical window for transmitting the laser beam of the lidar, without contacting the lidar. Furthermore, five-axis adjusting functions are provided, namely pitching, azimuth, direction along the optical axis z, and directions perpendicular to the optical axes x and y. Further, the adjusting structure module for positioning the lens group can independently fix the device beside the device without contacting the device through a fixing frame or a specific structural member, such as the triangular bracket 12.
Preferably, the lens group includes: the device comprises a main mirror and an auxiliary mirror, wherein the main mirror and the auxiliary mirror are both reflecting mirrors;
laser beams emitted by a radar to be calibrated enter the primary mirror after entering from the first end of the lens component, are reflected by the primary mirror, enter the secondary mirror, are reflected by the secondary mirror, and are output from the second end of the lens component;
the main mirror is an off-axis parabolic reflector, and a main mirror adjusting mechanism is arranged on the main mirror and used for adjusting the position of the main mirror to realize focusing.
Preferably, the mirror surface of the primary mirror and the mirror surface of the secondary mirror are both provided with metal film layers.
Preferably, the adjusting structure module for positioning the lens group is adapted to drive the lens group to move along the corresponding direction.
Referring to fig. 2, the apparatus includes a lens assembly for receiving the light pulses emitted by the lidar and for receiving the reflected light pulses. Further, the lens group is of a reflection type. Further, the reflective lens group adopts an off-axis parabolic light path. Specifically, the off-axis parabolic reflection type lens group adopts a mode of a primary mirror and a secondary mirror, and focusing can be realized in a mode of manually adjusting the primary mirror. The mirror surface of the primary mirror and the mirror surface of the secondary mirror are both provided with metal film layers. Compared with the traditional lens type design, the off-axis reflection type design has the following special advantages: (1) no secondary mirror is used for shielding; (2) the backward reflection of the end surface of the lens group to the emitted light pulse is small, and the interference on the laser radar receiving is small; (3) the reflective light path has the advantage of no chromatic aberration and can be suitable for being used in a wider wavelength range; (4) the metal coating layer is not sensitive to the working angle, the polarization state and the wavelength range of the light beam; (5) the design of the main mirror and the auxiliary mirror is adopted, the volume of the book part can be compressed, and the space is saved.
Furthermore, an optical fiber flange is arranged near the focal plane of the convergent optical axis of the primary mirror, and the optical fiber flange is an FC/APC optical fiber interface.
The device comprises an optical fiber attenuator which is adjustable, the attenuator can adjust the light intensity reflected back to the optical fiber, and the saturation of the laser radar sampling system is protected. The attenuator adopts a fiber coupling mode, and the fiber interface is in an FC/APC form. One end is butted with the lens group, and the other end is butted with the optical fiber delay line.
The device comprises a single mode optical fibre of which the length L is accurately determined, as a delay line instead of the path length S from the optical pulse in free space to a reference. The flight transit time t of the optical pulse in the single-mode fiber can be converted from the laser wavelength λ and the refractive index n of the single-mode fiber core diameter. The single-mode fiber replaces the path length of the optical pulse in free space in a short space range by means of coiling. Considering the influence of a dead zone existing in pulse tailing of the laser radar, the free space path length corresponding to the optical fiber of the device is at least two to N times of the radial resolution of the laser radar. The interfaces at both ends of the single mode fiber should be in the FC/APC form and the single mode fiber should be fixed in the package in a winding manner.
The device comprises a rotary table with adjustable rotating speed, as shown in figure 3. The rotary table 32 with adjustable rotation speed has the capability of forward and reverse rotation and can rotate continuously for 0-360 degrees. The adjustable rotating speed turntable is provided with a back reflection film 33 matched with the working wavelength on the side surface of the turntable, and the light pulse emitted by the single-mode optical fiber returns along the original path. The optical fiber coupler 31 is installed on the side vertical face of the rotary table with the adjustable rotating speed, the optical axis of the coupler forms an angle of 30 degrees with the tangent line of the side vertical face, and emitted laser can be converged on the retro-reflection film on the side face of the rotary table.
Preferably, the pulse doppler laser radar speed and distance measuring external calibration device further includes:
the fixing frame is connected with the adjusting structure module for positioning the lens group, and the fixing frame is used for assisting the adjusting structure module for positioning the lens group to fix the lens group at a target position;
preferably, the length of the single-mode fiber corresponding to the free space path is at least twice the resolution of the pulsed doppler lidar.
The embodiment of the invention provides a speed and distance measuring external calibration method for a pulse Doppler laser radar, which is based on the speed and distance measuring external calibration device for the pulse Doppler laser radar, and comprises the following steps:
after the adjusting structure module for positioning the lens group is connected with the lens group, the lens group is adjusted to a target position by adopting the adjusting structure module for positioning the lens group; the target position is the position of the lens group when the receiving optical axis of the lens group is superposed with the optical axis of the laser beam emitted by the radar to be calibrated;
the first end of the optical fiber attenuator enters the laser beam which is output by the second end of the lens component and is focused by the lens component, and the laser beam is attenuated by the optical fiber attenuator and then is output to the optical fiber delay line by the second end of the optical fiber attenuator;
the first end of the optical fiber delay line inputs the laser beam output by the optical fiber attenuator after being attenuated, and the laser beam is output to the optical fiber coupler from the second end of the optical fiber delay line after being delayed by the optical fiber delay line; the optical fiber delay line is a single-mode optical fiber with the length L, and the single-mode optical fiber is fixed in the package in a winding mode;
the optical fiber coupler receives the delayed laser beam output by the second end of the optical fiber delay line, and the laser beam is coupled by the optical fiber coupler and then output by the second end of the optical fiber coupler;
the coupled laser beam output from the second end of the optical fiber coupler meets a back reflection film arranged on the side surface of the rotary table and returns in the original path;
the optical fiber attenuator is characterized in that the first end of the optical fiber attenuator is connected with the second end of the lens assembly, the first end of the optical fiber delay line is connected with the second end of the optical fiber attenuator, the first end of the optical fiber coupler is connected with the second end of the optical fiber delay line, the optical axis of the coupled laser beam output from the second end of the optical fiber coupler is at an angle of 30 degrees with the tangent line of the side vertical surface of the turntable.
The principle of the external calibration method is the same as that of the external calibration device, and the description is omitted here.
Referring to fig. 4, an embodiment of the present invention provides a method for calibrating a pulse doppler laser radar, based on using the external calibration apparatus for measuring speed and distance of the pulse doppler laser radar, the method includes the following steps:
step S401, after the lens group is adjusted to a target position, generating a control instruction to control the rotary table to rotate according to a corresponding angular speed, wherein when a receiving optical axis of the lens group is superposed with an optical axis of a laser beam emitted by a radar to be calibrated, the position of the lens group corresponding to the target position is set;
step S402, after the turntable rotates stably, a pulse Doppler laser radar is started to emit laser beams and collect data, a data calculation system of the pulse Doppler laser radar is utilized to determine optical pulses reflected by the pulse Doppler laser radar speed and distance measurement external calibration device and corresponding sampling time sequences to obtain corresponding actual distance measurement information, and distance measurement calibration results are generated based on determined theoretical distance measurement information, wherein the theoretical distance measurement information is determined based on the distance between the laser and the side elevation of the turntable after the laser passes through optical fibers of the pulse Doppler laser radar speed and distance measurement external calibration device.
In the above embodiment, specifically, the laser radar outgoing beam angle is adjusted or confirmed, and if the laser radar has a servo function, the outgoing beam is adjusted to an angular position where the external calibration device is relatively easy to mount by adjusting the servo azimuth and pitch angle. The external calibration device is fixed on a triangular bracket or other mounting structures, and five-dimensional adjustment is carried out by utilizing the structural mounting module. The receiving optical axis of the lens group is approximately coincident with the optical axis of the laser radar, and the effect is shown in fig. 5.
The turntable part with adjustable rotating speed in the device is started, and the rotating direction and the rotating angular speed omega of the turntable are set through software. If the radius of the rotary table is R, calculating to obtain the rotation linear speed of the side vertical surface of the rotary table; and the included angle of the tangent line of the optical fiber coupler connected with the optical fiber delay line and the side vertical surface of the rotary table is 30 degrees, and the corresponding radial speed in the optical fiber coupler is obtained by calculation according to the cosine value and the rotary linear speed.
Laser emission and data acquisition of the laser radar are started, and the laser radar is provided with software to observe the light pulse reflected by the external calibration device and analyze ranging information according to sampling time sequence. As shown in fig. 6, the distance from the laser beam passing through the optical fiber of the external calibration device to the side elevation of the turn table is calculated. And the time delay t between the sampling trigger pulse and the reflected light pulse of the laser radar is adjusted, so that the range gate 1 can be ensured to fall at the position of 0m, and the ranging calibration is realized. And the radar calibration site limitation and the reference target object limitation are eliminated, and the identification time limitation is eliminated. The calibration steps are simplified. Meanwhile, calibration is carried out, and calibration efficiency and accuracy are improved.
Referring to fig. 7, preferably, the method further comprises:
step S403, calculating the measured radial Doppler frequency shift;
step S404, calculating to obtain theoretical Doppler frequency shift according to the radial rotating speed to be measured by the theoretical rotary table and a Doppler frequency shift calculation formula;
and S405, generating a velocity measurement calibration result based on the measured radial Doppler shift and the calculated theoretical Doppler shift.
A spectrum analysis module in software of the laser radar is started, and the measured radial Doppler frequency shift delta f can be calculated through a system of the laser radar. At this time, the radial rotating speed V which should be measured by the theoretical rotary table is knownrThe true radial Doppler shift Deltaf can be obtained according to a Doppler shift calculation formulaaBy the method, the true Doppler frequency shift error delta f-delta f generated by the measurement of the laser radar and the actual operation of the turntable can be calculatedaThereby realizing the speed measurement calibration.
And the radar calibration site limitation and the reference target object limitation are eliminated, and the identification time limitation is eliminated. The calibration steps are simplified. Meanwhile, calibration is carried out, and calibration efficiency and accuracy are improved.
Example 2
Referring to fig. 8, an embodiment of the present invention further provides a computer device, which may be a desktop computer, a notebook computer, a palm computer, a cloud server, and other computer devices. The computer device may include, but is not limited to, a processor and a memory, where the processor and the memory may be connected by a bus or other means.
The Processor may be a Central Processing Unit (CPU), other general purpose Processor, a Digital Signal Processor (DSP), a Graphics Processing Unit (GPU), an embedded Neural Network Processor (NPU), other dedicated deep learning coprocessor, an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), other Programmable logic device, discrete Gate or transistor logic device, discrete hardware component, or the like, or a combination thereof.
The memory, which is a non-transitory computer readable storage medium, may be used to store non-transitory software programs, non-transitory computer executable programs, and modules, such as program instructions/modules corresponding to the methods of the above-described method embodiments. The processor executes various functional applications and data processing of the processor by executing non-transitory software programs, instructions and modules stored in the memory, that is, the method in the above method embodiment is realized.
The memory may include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application program required for at least one function; the storage data area may store data created by the processor, and the like. Further, the memory may include high speed random access memory, and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid state storage device. In some embodiments, the memory optionally includes memory located remotely from the processor, and such remote memory may be coupled to the processor via a network. Examples of such networks include, but are not limited to, the internet, intranets, local area networks, mobile communication networks, and combinations thereof. The one or more modules are stored in the memory and, when executed by the processor, perform the methods of the above-described method embodiments.
Embodiments of the present invention also provide a non-transitory computer-readable storage medium storing computer-executable instructions, which are capable of executing the method in the above method embodiments. The non-transitory computer readable storage medium may be a magnetic Disk, an optical Disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a Flash Memory (Flash Memory), a Hard Disk (Hard Disk Drive, abbreviated as HDD), a Solid-State Drive (SSD), or the like; the non-transitory computer readable storage medium may also include a combination of memories of the above kind.
It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as a method, apparatus, computer device or non-transitory computer readable storage medium, all relating to or including a computer program product.
Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The features of the above-described embodiments may be arbitrarily combined, and for the sake of brevity, all possible combinations of the features in the above-described embodiments are not described, but should be construed as being within the scope of the present disclosure as long as there is no contradiction between the combinations of the features.
Obviously, the above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that various changes and modifications to the above description could be made by those skilled in the art without departing from the spirit of the present application. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. The utility model provides a calibration device outside pulse Doppler laser radar speed measurement range finding, its characterized in that, the device includes: the optical fiber attenuator is used for adjusting the position of the lens group;
the adjusting structure module for positioning the lens group is connected with the lens group and used for adjusting the lens group to a target position, wherein when a receiving optical axis of the lens group is superposed with an optical axis of a laser beam emitted by a radar to be calibrated, the position of the lens group corresponding to the target position is the target position;
the lens group is used for enabling laser beams emitted by a radar to be calibrated to enter from the first end of the lens component and be output from the second end of the lens component after being focused by the lens component;
the first end of the optical fiber attenuator is connected with the second end of the lens assembly, the laser beam output by the second end of the lens assembly and focused by the lens assembly enters from the first end of the optical fiber attenuator, and is output by the second end of the optical fiber attenuator after being attenuated by the optical fiber attenuator;
the first end of the optical fiber delay line is connected with the second end of the optical fiber attenuator, and the attenuated laser beam output by the optical fiber attenuator is input from the first end of the optical fiber delay line, is delayed by the optical fiber delay line and is output from the second section of the optical fiber delay line; the optical fiber delay line is a single-mode optical fiber with the length L, and the single-mode optical fiber is fixed in the package in a winding mode;
the first end of the optical fiber coupler is connected with the second end of the optical fiber delay line, and the delayed laser beam output by the second end of the optical fiber delay line is coupled by the optical fiber coupler and then output by the second end of the optical fiber coupler; the optical axis of the coupled laser beam output from the second end of the optical fiber coupler and the side vertical tangent line of the rotary table form an angle of 30 degrees;
and a retro-reflection film is arranged on the side surface of the rotary table and returns the coupled laser beam output from the second end of the optical fiber coupler to the acquisition end of the radar to be calibrated according to the original path.
2. The device for calibrating speed and distance of a pulsed doppler laser radar according to claim 1, wherein the lens set comprises: the device comprises a main mirror and an auxiliary mirror, wherein the main mirror and the auxiliary mirror are both reflecting mirrors;
laser beams emitted by a radar to be calibrated enter the primary mirror after entering from the first end of the lens component, are reflected by the primary mirror, enter the secondary mirror, are reflected by the secondary mirror, and are output from the second end of the lens component;
the main mirror is an off-axis parabolic reflector, and a main mirror adjusting mechanism is arranged on the main mirror and used for adjusting the position of the main mirror to realize focusing.
3. The device for external calibration of speed and distance measurement of pulse Doppler laser radar according to claim 2, wherein the mirror surface of the primary mirror and the mirror surface of the secondary mirror are both provided with metal film layers.
4. The device for calibrating speed and distance measurement according to claim 3,
the adjusting structure module for positioning the lens group is suitable for driving the lens group to move along the corresponding direction.
5. The device for calibrating the speed and the distance of the pulse Doppler laser radar according to claim 4, further comprising:
the fixing frame is connected with the adjusting structure module for positioning the lens group, and the fixing frame is used for assisting in positioning the adjusting structure module for positioning the lens group and fixing the lens group at a target position.
6. The device according to claim 5, wherein the length of the single-mode fiber corresponding to the free space path is at least twice the radial resolution of the pulsed Doppler lidar.
7. An external calibration method for speed measurement and distance measurement of pulse doppler laser radar based on the use of the external calibration device for speed measurement and distance measurement of pulse doppler laser radar according to any one of claims 1 to 6, the method comprising:
after the adjusting structure module for positioning the lens group is connected with the lens group, the lens group is adjusted to a target position by adopting the adjusting structure module for positioning the lens group; the target position is the position of the lens group when the receiving optical axis of the lens group is superposed with the optical axis of the laser beam emitted by the radar to be calibrated;
the first end of the optical fiber attenuator enters the laser beam which is output by the second end of the lens component and is focused by the lens component, and the laser beam is attenuated by the optical fiber attenuator and then is output to the optical fiber delay line by the second end of the optical fiber attenuator;
the first end of the optical fiber delay line inputs the laser beam output by the optical fiber attenuator after being attenuated, and the laser beam is output to the optical fiber coupler from the second end of the optical fiber delay line after being delayed by the optical fiber delay line; the optical fiber delay line is a single-mode optical fiber with the length L, and the single-mode optical fiber is fixed in the package in a winding mode;
the optical fiber coupler receives the delayed laser beam output by the second end of the optical fiber delay line, and the laser beam is coupled by the optical fiber coupler and then output by the second end of the optical fiber coupler;
the coupled laser beam output from the second end of the optical fiber coupler meets a back reflection film arranged on the side surface of the rotary table and returns in the original path;
the optical fiber attenuator is characterized in that the first end of the optical fiber attenuator is connected with the second end of the lens assembly, the first end of the optical fiber delay line is connected with the second end of the optical fiber attenuator, the first end of the optical fiber coupler is connected with the second end of the optical fiber delay line, the optical axis of the coupled laser beam output from the second end of the optical fiber coupler is at an angle of 30 degrees with the tangent line of the side vertical surface of the turntable.
8. A calibration method of pulse Doppler laser radar based on the use of the device for measuring speed and distance and calibrating out the pulse Doppler laser radar according to any one of claims 1 to 6, wherein the method comprises the following steps:
after the lens group is adjusted to a target position, generating a control instruction to control the rotary table to rotate according to a corresponding angular speed, wherein when a receiving optical axis of the lens group is superposed with an optical axis of a laser beam emitted by a radar to be calibrated, the position of the lens group corresponding to the target position is the target position;
after the turntable stably rotates, starting a pulse Doppler laser radar to emit a laser beam and collect data, determining a light pulse reflected by the pulse Doppler laser radar speed and distance measuring external calibration device and a corresponding sampling time sequence by utilizing a data calculation system of the pulse Doppler laser radar, obtaining corresponding actual distance measuring information, and generating a distance measuring calibration result based on determined theoretical distance measuring information, wherein the theoretical distance measuring information is determined based on the distance between the laser and the side vertical surface of the turntable after the laser passes through an optical fiber of the pulse Doppler laser radar speed and distance measuring external calibration device.
9. The pulsed doppler lidar calibration method of claim 8, further comprising:
calculating the measured radial Doppler frequency shift;
calculating to obtain theoretical Doppler shift according to the radial rotating speed to be measured by the theoretical rotary table and a Doppler shift calculation formula;
and generating a speed measurement calibration result based on the measured radial Doppler shift and the calculated theoretical Doppler shift.
10. A computer device, comprising: a memory and a processor, the memory and the processor being communicatively connected to each other, the memory storing therein computer instructions, and the processor executing the computer instructions to perform the pulsed doppler lidar calibration method of any of claims 8 or 9.
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| CN202111673580.7A CN114280563A (en) | 2021-12-31 | 2021-12-31 | Pulse Doppler laser radar speed and distance measurement external calibration device and method |
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