Method for calibrating optical axis and inertial navigation axis of optical system in airborne environment
By designing the inertial guide shaft calibration device, the point light source, light emission/return mirror group and image sensor are used to detect the deviation between the optical axis and the inertial guide shaft of the optical system in an on-board environment, and solve the problem of real-time calibration in the prior art. Problem, improving aircraft mission execution capabilities.
Patent Information
- Application Number
- CN202411508458.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-28
- Publication Date
- 2025-02-18
AI Technical Summary
The prior art is difficult to detect and calibrate the deviation between the optical axis and the inertial guide axis in real time in an airborne environment, resulting in complex operations and difficult to meet aircraft mission requirements.
Design an inertial guide shaft calibration device, including a point light source, a light emission/return mirror group and an image sensor, and obtain the errors between the optical system and the inertial guide shaft by constructing a test optical path, and calculate the deviation between the optical axis and the inertial guide shaft by using an image processor. .
Real-time detection and calibration of the errors of optical systems and inertial navigation in an airborne environment, improves aircraft mission execution capabilities and simplifies the calibration process of the equipment.
Smart Images
Figure CN119469679A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of optical system calibration, and in particular relates to a method for calibrating an optical axis and an inertial guide axis of an optical system in an airborne environment. Background Art
[0002] Inertial navigation technology uses inertia as the coordinate system to measure its own attitude, heading and other information. The optoelectronic system uses itself as the reference and can measure the angle of the target. With the development of inertial navigation technology, more and more optoelectronic devices are equipped with inertial navigation systems.
[0003] The temperature, vibration and air pressure environment of airborne optoelectronic products are changing. Airborne optoelectronic products and inertial navigation are installed on the corresponding structure. Due to the characteristics of the structural materials and various stresses, the components are offset relative to the original position. As a result, the optical axis and inertial navigation axis of the optoelectronic product may have their own deviations. How to measure the inertial navigation axis and optical axis at the required time. In particular, measuring the inertial navigation output error and the indication deviation of the airborne optoelectronic system in the airborne changing environment has become a problem that needs to be solved in actual use.
[0004] In the ground test environment, the test inertial navigation axis and the optical axis of the optoelectronic product are placed on a high-precision turntable, and the target source needs to be equipped with a self-aligned collimator. Since the collimator is large in size and inconvenient to install on the aircraft, the existing technology uses a collimator for detection on the ground. The detection can only be completed on the ground, and the test inertial navigation axis and the optical axis of the optoelectronic product cannot be detected in real time, which makes it difficult to meet the actual mission requirements of the aircraft. At the same time, during the routine inspection before the flight, the workload of disassembly, assembly and calibration of the equipment is large, which is bound to affect the normal take-off of the aircraft. Summary of the invention
[0005] Technical issues to be solved:
[0006] In order to avoid the shortcomings of the prior art, the present invention provides a calibration method for the optical axis of an optical system and an inertial navigation axis in an airborne environment, wherein the optical axis of the optical system and the inertial navigation axis are associated with each other through an inertial navigation axis calibration device, and the deviation between the optical axis of the optical system and the inertial navigation axis calibration device and the deviation between the inertial navigation axis calibration device are obtained respectively, and then the deviation between the optical axis of the optical system and the inertial navigation axis is calculated. The present invention solves the problem that the prior art airborne long-wave infrared search system is complicated to operate and difficult to realize real-time detection in an airborne environment.
[0007] The technical solution of the present invention is: a method for calibrating the optical axis and the inertial navigation axis of an optical system in an airborne environment, and the specific steps are as follows:
[0008] Design an inertial navigation axis calibration device, which includes a point light source, a light emitting / returning mirror group, and an image sensor;
[0009] A first test optical path is constructed between the inertial navigation axis and the inertial navigation axis calibration device. The light emitted by the point light source of the inertial navigation axis calibration device is transmitted to the inertial navigation through the light transmitting / returning mirror group and then transmitted back to the image sensor to obtain a first target image.
[0010] A second test optical path is constructed between the optical system under test and the inertial navigation alignment device. The light emitted by the point light source of the inertial navigation alignment device is transmitted to the optical system under test through the light transmitting / returning mirror group, and a second target image is obtained through the sensor of the optical system under test.
[0011] The first target image and the second target image are compared and processed to obtain the errors of the optical axis and the inertial navigation axis of the optical system under test.
[0012] A further technical solution of the present invention is: the light emitting / returning mirror group includes a beam splitter and a reflective off-axis light pipe arranged along the light path, the beam splitter divides the focus of the reflective off-axis light pipe into two mutually conjugated focuses, and the light source and the image sensor are respectively arranged at the two focuses.
[0013] A further technical solution of the present invention is: the method for acquiring the first target image is that the outgoing light of the point light source is reflected by a beam splitter to a reflective off-axis light pipe, the reflective off-axis light pipe reflects the incident light and focuses it into parallel light and emits it to the reflective surface of the inertial navigation system, and then reflects it to the reflective off-axis light pipe through the inertial navigation reflective surface, and the return light is transmitted to the image sensor through the beam splitter to obtain the first target image, that is, the center deviation of the midpoint target between the inertial navigation axis and the inertial navigation axis calibration device is obtained.
[0014] A further technical solution of the present invention is: a method for acquiring the second target image is that the outgoing light of the point light source is reflected by a beam splitter to a reflective off-axis light pipe, and the reflective off-axis light pipe reflects and focuses the incident light into parallel light and emits it to the optical system under test, and images are formed by a sensor of the optical system under test to obtain the second target image, that is, to obtain the center deviation of the point target between the optical system under test and the inertial navigation axis calibration device.
[0015] A calibration system for an optical axis and an inertial navigation axis of an optical system in an airborne environment comprises an inertial navigation axis calibration device and an image processor. The optical axis of a measured optical system is associated with the inertial navigation axis by the inertial navigation axis calibration device, and the center deviation between the measured optical system and a midpoint target of the inertial navigation axis calibration device and the center deviation between the inertial navigation axis and the midpoint target of the inertial navigation axis calibration device are respectively measured. The image processor calculates the two center deviations to obtain the deviation between the optical axis of the measured optical system and the inertial navigation axis.
[0016] A further technical solution of the present invention is: the inertial navigation axis calibration device comprises a point light source, a beam splitter, a reflective off-axis light pipe, and an image sensor arranged along the optical path;
[0017] In the optical path formed with the inertial navigation system, the outgoing light of the point light source is reflected by the beam splitter to the reflective off-axis light pipe, and the reflective off-axis light pipe reflects and focuses the incident light into parallel light and emits it to the reflective surface of the inertial navigation system. The parallel light is then reflected by the reflective surface of the inertial navigation system to the reflective off-axis light pipe, and the return light is transmitted to the image sensor through the beam splitter to obtain the first target image.
[0018] In the optical path formed by the inertial navigation of the optical system under test, the outgoing light of the point light source is reflected by the beam splitter to the reflective off-axis light pipe, which reflects the incident light and focuses it into parallel light and emits it to the optical system under test, and forms an image through the sensor of the optical system under test to obtain a second target image.
[0019] A further technical solution of the present invention is that the beam splitter divides the focus of the reflective off-axis light pipe into two mutually conjugated focuses, and the light source and the image sensor are respectively arranged on the two focuses.
[0020] A further technical solution of the present invention is that the inertial navigation reflection surface is a reflection surface or a prism.
[0021] A further technical solution of the present invention is that the inertial navigation reflection surface is perpendicular to the light emitted by the inertial navigation axis correction device.
[0022] A further technical solution of the present invention is that the front and rear surfaces of the beam splitter are respectively coated with a beam splitting film and an anti-reflection film to reflect and transmit light.
[0023] Beneficial Effects
[0024] The beneficial effects of the present invention are as follows: the present invention provides a method for calibrating the optical axis of the test optical system and the inertial navigation axis in an airborne space and airborne changing environment. In the application of the actual airborne environment, the inertial navigation axis calibration device installed next to the test optical system and the inertial navigation is used to obtain the errors of the optical system and the inertial navigation relative to the inertial navigation axis calibration device by direct observation or indirect measurement, and then the error between the optical system and the inertial navigation is calculated by a settlement image processor. The present invention can detect the errors of the optical system and the inertial navigation in real time, thereby performing error compensation, obtaining an accurate target position, and updating the flight mission of the aircraft in real time according to the detection results, thereby improving the mission execution capability.
[0025] The inertial navigation alignment device in the present invention is based on the reflection and transmission characteristics of the spectroscope, and can reflect the point light source transmitting tube, and then transmit the light returning along the original path to the image sensor for imaging. It has the advantages of simple structure and small size, so the device occupies a small space and is very suitable for airborne. Moreover, the entire device can complete the calibration of the optical system and the inertial navigation in the aircraft, and no detection on the ground is required. At the same time, it can detect the infrared search system in real time, and has a simple structure, convenient operation, high efficiency, and effectively improves the aircraft's mission execution capability. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Figure 1 It is a structural schematic diagram of a method for calibrating an optical axis and an inertial navigation axis of an optical system in an airborne environment of the present invention;
[0027] Explanation of reference numerals: 1-optical system under test, 2-INS reflection surface, 3-INS axis calibration device, 4-reflective off-axis light pipe, 5-CMOS, 6-point light source, 7-beam splitter, 8-INS, 9-sensor, 10-image processor. DETAILED DESCRIPTION
[0028] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, but should not be construed as limiting the present invention.
[0029] Based on the problem that in the prior art, the inertial navigation axis and the optical axis of the optoelectronic product need to be placed on a high-precision turntable in a ground test environment, and the target source needs to be equipped with a self-aligned collimator. Since the collimator is large in size and inconvenient to install on an aircraft, it is impossible to detect the error of the optical axis of the optical system and the inertial navigation axis in real time. The present invention provides a calibration method for the optical axis of the optical system and the inertial navigation axis in an airborne environment, and the specific steps are as follows:
[0030] Step 1: Design an inertial navigation axis calibration device, which includes a point light source, a light emitting / returning mirror group, and an image sensor;
[0031] Step 2: construct a first test optical path between the inertial navigation axis and the inertial navigation axis calibration device, and the light emitted by the point light source of the inertial navigation axis calibration device is transmitted to the inertial navigation through the light transmitting / returning mirror group and then transmitted back to the image sensor to obtain a first target image;
[0032] Step 3: construct a second test optical path between the optical system under test and the inertial navigation alignment device, and the light emitted by the point light source of the inertial navigation alignment device is transmitted to the optical system under test through the light transmitting / returning mirror group, and the second target image is obtained through the sensor of the optical system under test;
[0033] Step 4: Compare the first target image and the second target image to obtain the errors of the optical axis and the inertial navigation axis of the optical system under test.
[0034] Specifically, the light emission / return mirror group includes a beam splitter and a reflective off-axis light pipe arranged along the light path, the beam splitter divides the focus of the reflective off-axis light pipe into two mutually conjugated focuses, and the light source and the CMOS image sensor are respectively arranged at the two focuses. The positions of the CMOS image sensor and the point light source are strictly required to remain fixed, and remain fixed when the environmental conditions change. The positions of the CMOS and the point light source can be measured by the self-alignment method.
[0035] Specifically, the method for acquiring the first target image is that the outgoing light of the point light source is reflected by a beam splitter to a reflective off-axis light pipe, the reflective off-axis light pipe reflects the incident light and focuses it into parallel light and emits it to the reflective surface of the inertial navigation system, and then reflects it to the reflective off-axis light pipe through the inertial navigation reflective surface, and the return light is transmitted to the image sensor through the beam splitter to obtain the first target image, that is, the center deviation of the midpoint target between the inertial navigation axis and the inertial navigation axis calibration device is obtained.
[0036] Specifically, the method for acquiring the second target image is that the outgoing light of the point light source is reflected by a beam splitter to a reflective off-axis light pipe, and the reflective off-axis light pipe reflects the incident light and focuses it into parallel light, which is emitted to the optical system under test, and is imaged by a sensor of the optical system under test to obtain the second target image, that is, the center deviation of the midpoint target between the optical system under test and the inertial navigation axis calibration device is obtained.
[0037] The present invention discloses a calibration system for an optical axis and an inertial navigation axis of an optical system in an airborne environment. The system comprises an inertial navigation axis calibration device and an image processor. The optical axis of a measured optical system is associated with the inertial navigation axis by the inertial navigation axis calibration device. The center deviation between a midpoint target of the measured optical system and the inertial navigation axis calibration device and the center deviation between the inertial navigation axis and the midpoint target of the inertial navigation axis calibration device are respectively measured. The image processor calculates the two center deviations to obtain the deviation between the optical axis of the measured optical system and the inertial navigation axis.
[0038] The inertial navigation axis calibration device includes a point light source, a beam splitter, a reflective off-axis light pipe, and a CMOS image sensor arranged along the optical path; the point light source is a full-spectrum light source that can emit the required spectrum. Due to the two-time light splitting attenuation after the beam splitter, the energy requirement for the point light source is relatively high. The mirror surface of the beam splitter forms a certain angle with the optical axis, and the beam splitting of the beam splitter needs to consider the wavelength of the split light and the selected material.
[0039] Specifically, the inertial navigation reflection surface is a reflection surface or a prism, which is an integrated structure with the inertial navigation. The azimuth and elevation of the inertial navigation reflection surface can represent the direction of the inertial navigation axis.
[0040] Specifically, the inertial navigation reflection surface is perpendicular to the light emitted by the inertial navigation axis alignment device.
[0041] Specifically, the front and back surfaces of the beam splitter are coated with films, one is the beam splitter film and the other is the anti-reflection film. The anti-reflection film transmits the wavelength used as much as possible; the beam splitter film is 50% transparent and 50% reflective for the short wavelength used by CMOS. In order to reduce the cost, process and performance of the beam splitter film preparation, the beam splitting wavelength cannot be less than the transmission wavelength. The material of the beam splitter film needs to consider the selection of materials with a low refractive index.
[0042] The calibration system of the present invention has small volume, simple structure, and can adapt to different optical wavelengths as required, so it has great application value.
[0043] The above technical solution is further described below with reference to the accompanying drawings:
[0044] Reference Figure 1 As shown, in the calibration system of the optical axis of the optical system and the inertial navigation axis in an airborne environment, in the airborne environment, the optical axis of the optical system and the inertial navigation axis system are composed of a test optical system 1, an inertial navigation reflection surface 2, and an inertial navigation axis calibration device 3 to form a test optical path. The inertial navigation axis calibration device 3 is composed of a reflective off-axis light pipe 4, a CMOS 5, a point light source 6, a beam splitter 7, an inertial navigation 8, a sensor 9, and an image processing component 10, a total of 10 parts.
[0045] The inertial navigation axis calibration device 3 is strictly tested before being installed in the equipment, and it is required to ensure that the positions of CMOS5 and point light source 6 remain unchanged under the environment that may be involved. The inertial navigation axis system is a reflection system, and the inertial navigation 8 is installed behind the reflective objective lens. The reflective objective lens has a small hole, and the inertial navigation reflector 2 is perpendicular to the light emitted by the inertial navigation axis calibration device 3. The optical system 1 under test is a medium and long wave system, and CMOS5 is a visible light band.
[0046] The front surface coating of the beam splitter 7 is required to be 50% transmission and 50% reflection in the visible light band, and the medium and long wave systems are transmission. The size of the inertial navigation reflective surface 2 is 15mm*15mm, and the objective lens of the optical system 1 to be measured is punched Optical aperture of inertial navigation alignment device 3
[0047] The point light source 6 emits wavelengths covering visible, medium and long waves, which are transmitted through the spectroscope to the reflective off-axis light pipe 4. Since the point light source 6 is located at the focus of the reflective off-axis light pipe 4, the light emitted from the inertial navigation alignment device 3 becomes a parallel beam. The beam diameter is arrive The medium and long waves hit the optical system 1 under test, and are converged to the sensor 9, which transmits the image to the image processing component 10. The beam diameter is As can be seen in the figure, the light beam hits the inertial navigation reflection surface 2, which returns to the original optical path and hits the reflective off-axis light pipe 4. The light beam becomes a converging light beam and reaches the beam splitter 7. 50% of the light beam is reflected to the CMOS 5 and converges into an image. The CMOS image at this time contains the information of the inertial navigation position deviation. The image processing component 10 processes these two images to obtain the optical axis and inertial navigation axis errors.
[0048] When the optical axis of the optical system and the inertial guide axis need to be calibrated in the present invention, the optical axis of the optical system and the inertial guide need to be aligned so that the reflective off-axis light pipe 4 is aligned with the small hole. At this time, detection can begin.
[0049] Since the optical axis of the optical system and the inertial navigation axis are calibrated in the airborne environment of the present invention, the inertial navigation axis calibration device 3 is installed on the aircraft, which occupies a small space and is very suitable for installation on the aircraft. In addition, no external reference target is required, and the optical axis of the optical system and the inertial navigation axis calibration can be detected at any time, which is not affected by the flight status of the aircraft, so real-time detection can be achieved. Therefore, the operation is convenient, the self-checking time is saved, and it is conducive to improving the aircraft mission execution capability.
[0050] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and intent of the present invention.
Claims
1. A method for calibrating the optical axis and the inertial navigation axis of an optical system in an airborne environment, characterized in that The specific steps are as follows: Design an inertial navigation axis calibration device, which includes a point light source, a light emitting / returning mirror group, and an image sensor; A first test optical path is constructed between the inertial navigation axis and the inertial navigation axis calibration device. The light emitted by the point light source of the inertial navigation axis calibration device is transmitted to the inertial navigation through the light transmitting / returning mirror group and then transmitted back to the image sensor to obtain a first target image. A second test optical path is constructed between the optical system under test and the inertial navigation alignment device. The light emitted by the point light source of the inertial navigation alignment device is transmitted to the optical system under test through the light transmitting / returning mirror group, and a second target image is obtained through the sensor of the optical system under test. The first target image and the second target image are compared and processed to obtain the errors of the optical axis and the inertial navigation axis of the optical system under test.
2. According to claim 1, a method for calibrating the optical axis and the inertial navigation axis of an optical system in an airborne environment, characterized in that: The light emission / return mirror group includes a beam splitter and a reflective off-axis light pipe arranged along the light path. The beam splitter divides the focus of the reflective off-axis light pipe into two mutually conjugated focuses. The light source and the image sensor are respectively arranged at the two focuses.
3. According to claim 2, a method for calibrating the optical axis of an optical system and the inertial navigation axis in an airborne environment, characterized in that: The method for acquiring the first target image is that the outgoing light of the point light source is reflected by a beam splitter to a reflective off-axis light pipe, and the reflective off-axis light pipe reflects and focuses the incident light into parallel light and emits it to the reflective surface of the inertial navigation system. The parallel light is then reflected by the reflective surface of the inertial navigation system to the reflective off-axis light pipe, and the return light is transmitted to the image sensor through a beam splitter to obtain the first target image, that is, the center deviation of the midpoint target between the inertial navigation axis and the inertial navigation axis calibration device is obtained.
4. According to claim 2, a method for calibrating the optical axis of an optical system and an inertial navigation axis in an airborne environment, characterized in that: The method for acquiring the second target image is that the outgoing light of the point light source is reflected by a beam splitter to a reflective off-axis light pipe, which reflects the incident light and focuses it into parallel light and emits it to the optical system under test, and forms an image through the sensor of the optical system under test to obtain the second target image, that is, the center deviation of the midpoint target between the optical system under test and the inertial navigation axis calibration device is obtained.
5. A calibration system for the optical axis and the inertial navigation axis of an optical system in an airborne environment, used for implementing the calibration method for the optical axis and the inertial navigation axis of an optical system in an airborne environment as claimed in any one of claims 1 to 4; characterized in that: The invention comprises an inertial navigation axis calibration device and an image processor. The optical axis of the optical system to be measured is associated with the inertial navigation axis through the inertial navigation axis calibration device. The center deviation of the midpoint target between the optical system to be measured and the inertial navigation axis calibration device, and the center deviation of the midpoint target between the inertial navigation axis and the inertial navigation axis calibration device are measured respectively. The image processor calculates the two center deviations to obtain the deviation between the optical axis of the optical system to be measured and the inertial navigation axis.
6. The calibration system for optical axis and inertial navigation axis of an optical system in an airborne environment according to claim 5, characterized in that: The inertial navigation axis calibration device comprises a point light source, a beam splitter, a reflective off-axis light pipe, and an image sensor arranged along the optical path; In the optical path formed with the inertial navigation system, the outgoing light of the point light source is reflected by the beam splitter to the reflective off-axis light pipe, and the reflective off-axis light pipe reflects and focuses the incident light into parallel light and emits it to the reflective surface of the inertial navigation system. The parallel light is then reflected by the reflective surface of the inertial navigation system to the reflective off-axis light pipe, and the return light is transmitted to the image sensor through the beam splitter to obtain the first target image. In the optical path formed by the inertial navigation of the optical system under test, the outgoing light of the point light source is reflected by the beam splitter to the reflective off-axis light pipe, which reflects the incident light and focuses it into parallel light and emits it to the optical system under test, and forms an image through the sensor of the optical system under test to obtain a second target image.
7. The calibration system for optical axis and inertial navigation axis of an optical system in an airborne environment according to claim 6, characterized in that: The beam splitter divides the focus of the reflective off-axis light pipe into two mutually conjugated focuses, and the light source and the image sensor are respectively arranged on the two focuses.
8. The calibration system for optical axis and inertial navigation axis of an optical system in an airborne environment according to claim 6, characterized in that: The inertial navigation reflection surface is a reflection surface or a prism.
9. The calibration system for optical axis and inertial navigation axis of an optical system in an airborne environment according to claim 8, characterized in that: The inertial navigation reflection surface is perpendicular to the light emitted by the inertial navigation axis correction device.
10. The calibration system for optical axis and inertial navigation axis of an optical system in an airborne environment according to claim 6, characterized in that: The front and rear surfaces of the beam splitter are respectively coated with a beam splitting film and an anti-reflection film to reflect and transmit light.