A UAV-borne mapping device and method

Abstract

This invention discloses an unmanned aerial vehicle (UAV)-borne surveying device and method, belonging to the field of aerial surveying. The UAV-borne surveying device includes a scanning CCD, a registration lens, a digital micromirror device, a first reflecting mirror, a second reflecting mirror, a front-viewing lens, a rear-viewing lens, and a housing. The UAV-borne surveying device employs a four-line array scanning system to provide sufficient data for optimal solution selection. Compared with existing technologies, the UAV-borne surveying device provided by this invention has a compact and portable structure. The UAV-borne surveying method provided by this invention utilizes the principles of triangulation and a transfer station measurement method, achieving high measurement accuracy.

Description

Technical Field

[0001] This invention relates to an unmanned aerial vehicle (UAV)-borne surveying device and method, belonging to the field of aerial surveying. Background Technology

[0002] The development of drones has provided a new approach to topographic mapping, thereby further advancing aerial surveying technology. However, the limitations of drone onboard capabilities necessitate compact and portable surveying equipment. Traditional aerial surveying equipment features a multi-camera lens structure with forward-looking, front-looking, and rear-looking detectors, whose size and weight are unsuitable for drone platforms. Summary of the Invention

[0003] In view of the above-mentioned prior art, the present invention provides an unmanned aerial vehicle (UAV)-borne mapping device and method to solve the aforementioned problems.

[0004] The technical solution for implementing an unmanned aerial vehicle (UAV)-borne mapping device according to the present invention is as follows: The device includes a scanning CCD, a registration lens, a digital micromirror device (DMM), a first reflector, a second reflector, a front-viewing lens, a rear-viewing lens, and a housing; the front-viewing lens and the rear-viewing lens scan terrain information respectively, which is reflected onto the DMM via the first and second reflectors; the DMM consists of a base surface and a two-dimensional array of micromirrors; the micromirrors have two flip states, on and off. When in the on state, the micromirrors deflect by +12°, and the ground scanning strip is tilted forward; when in the off state, the micromirrors deflect by -12°, and the ground scanning strip is tilted backward; the registration lens is used to align the CCD pixels with the micromirrors of the DMM; the scanning CCD consists of CCD scan line I, CCD scan line II, CCD scan line III, and CCD scan line IV, which record the scan strip data; the housing is used to fix the optical elements and seal the optical path to prevent external interference light from entering.

[0005] The first and second reflecting mirrors, the front-viewing lens and the rear-viewing lens are symmetrically arranged; the registered CCD pixels correspond one-to-one with the micromirror elements of the digital micromirror device.

[0006] The present invention proposes an unmanned aerial vehicle (UAV)-borne surveying method, which utilizes the aforementioned UAV-borne surveying device and follows these steps:

[0007] Step 1: Calibrate and obtain the imaging internal and external parameters of the device of the present invention; the UAV flies at a certain horizontal altitude to perform four-strip scanning mapping of the ground, and the pose data is provided by the gyroscope.

[0008] Step 2: Adjust the position of the pixels of the scanning CCD and the micromirror elements of the digital micromirror device, as well as the magnification of the registration lens, so that one CCD pixel corresponds to one micromirror element; select four scanning lines I, II, III, and IV of the CCD, which correspond to four rows of micromirror elements of the digital micromirror device, respectively.

[0009] Step 3: Control the flip state of the micromirror array of the digital micromirror device. The first and third rows are in the on state, and the second and fourth rows are in the off state.

[0010] Step 4: Scan line I collects data for strip c by reflecting the data from the third row of micromirrors and the second mirror of the digital micromirror device; Scan line II collects data for strip a by reflecting the data from the fourth row of micromirrors and the second mirror of the digital micromirror device; Scan line III collects data for strip d by reflecting the data from the first row of micromirrors and the first mirror of the digital micromirror device; Scan line IV collects data for strip b by reflecting the data from the second row of micromirrors and the first mirror of the digital micromirror device.

[0011] Step 5: The four CCD scan lines continuously scan the ground in one synchronous cycle, generating four strip images I. a I b I c I d .

[0012] Step Six: Image Processing - Determine the image coordinates (x, y) of the same point on the ground in the four-strip image. a ,y a ), (x b ,y b ), (x c ,y c ) and (x d ,y d ).

[0013] Step 7: Select images from two imaging directions according to the measurement range, such as I a and I b I c and I d I a and I d I c and I b ; with I a and I d For example, based on the real-time pose distance of the gyroscope, the CCD scanning frame rate, and the coordinates of the two images, the viewpoint baseline length D of scan lines II and III can be calculated.

[0014] Step 8: Based on the triangulation method, given the baseline length D of the viewpoint and the two viewing angles θ1 and θ2 of scan lines II and III, the elevation difference H between the target point and the UAV's horizontal flight surface can be calculated, thus realizing UAV-borne mapping of this ground target.

[0015] Compared with the prior art, the beneficial effects of the present invention are:

[0016] The UAV-borne mapping device and method provided by this invention employ a four-line array scanning system to provide sufficient data for optimal solution selection. The beam-splitting structure of a digital micromirror array reduces the system's size. Compared to existing technologies, the UAV-borne mapping device provided by this invention has a compact and portable structure. The UAV-borne mapping method provided by this invention utilizes the principles of triangulation and a station-based measurement method, resulting in high measurement accuracy. Attached Figure Description

[0017] Figure 1 This is a structural diagram of the UAV-borne mapping device provided by the present invention;

[0018] Figure 2 This is a schematic diagram of the UAV triangulation principle of the present invention.

[0019] In the diagram: 1-Scanning CCD, 2-Registration lens, 3-Digital micromirror device, 4-First reflecting mirror, 5-Second reflecting mirror, 6-Front-viewing lens, 7-Rear-viewing lens, 8-Housing shell, 9-Ground target, Ⅰ-CCD scanning line Ⅰ, Ⅱ-CCD scanning line Ⅱ, Ⅲ-CCD scanning line Ⅲ, Ⅳ-CCD scanning line Ⅳ. Detailed Implementation

[0020] The present invention will now be described in further detail with reference to specific embodiments.

[0021] like Figure 1 As shown, this invention discloses an unmanned aerial vehicle (UAV)-borne mapping device, comprising a scanning CCD 1, a registration lens 2, a digital micromirror device (DMM) 3, a first reflector 4, a second reflector 5, a front-viewing lens 6, a rear-viewing lens 7, and a housing 8. The front-viewing lens 6 and the rear-viewing lens 7 scan terrain information, which is reflected by the first reflector 4 and the second reflector 5 onto the DMM 3. The DMM 3 consists of a base surface and a two-dimensional array of micromirrors. The micromirrors have two flip states: on and off. When in the on state, the micromirrors deflect by +12°, causing the ground scan strip to tilt forward; when in the off state, the micromirrors deflect by -12°, causing the ground scan strip to tilt backward. The registration lens 2 is used to align the CCD pixels with the micromirrors of the DMM 3. The scanning CCD 1 consists of CCD scan lines I, II, III, and IV, recording the scan strip data. The housing 8 is used to fix the optical elements and seal the optical path to prevent external interference light from entering.

[0022] The first reflecting mirror 4 and the second reflecting mirror 5, the front-viewing lens 6 and the rear-viewing lens 7 are symmetrically arranged; the registered CCD pixels correspond one-to-one with the micromirror elements of the digital micromirror device.

[0023] The present invention proposes an unmanned aerial vehicle (UAV)-borne surveying method, which utilizes the aforementioned UAV-borne surveying device and follows these steps:

[0024] Step 1: Calibrate and obtain the imaging internal and external parameters of the device of the present invention; the UAV flies at a certain horizontal altitude to perform four-strip scanning mapping of the ground, and the pose data is provided by the gyroscope.

[0025] Step 2: Adjust the position of the pixels of the scanning CCD1 and the micromirror elements of the digital micromirror device 3, as well as the magnification of the registration lens, so that one CCD pixel corresponds to one micromirror element; select four scanning lines I, II, III, and IV of the CCD, which correspond to four rows of micromirror elements of the digital micromirror device 3, respectively.

[0026] Step 3: Control the flip state of the micromirror array of the digital micromirror device 3. The first and third rows are in the on state, and the second and fourth rows are in the off state.

[0027] Step 4: Scan line I is reflected by the third row of micromirrors and the second mirror of digital micromirror device 3 to acquire data for strip c; scan line II is reflected by the fourth row of micromirrors and the second mirror of digital micromirror device 3 to acquire data for strip a; scan line III is reflected by the first row of micromirrors and the first mirror of digital micromirror device 3 to acquire data for strip d; scan line IV is reflected by the second row of micromirrors and the first mirror of digital micromirror device 3 to acquire data for strip b.

[0028] Step 5: The four CCD scan lines continuously scan the ground in one synchronous cycle, generating four strip images I. a I b I c I d .

[0029] Step Six: Image Processing - Determine the image coordinates (x, y) of the same point on the ground in the four-strip image. a ,y a ), (x b ,y b ), (x c ,y c ) and (x d ,y d ).

[0030] Step 7: Select images from two imaging directions according to the measurement range, such as I a and I b I c and I d I a and I d I c and I b ; with I a and I d For example, based on the real-time pose distance of the gyroscope, the CCD scanning frame rate, and the coordinates of the two images, the viewpoint baseline length D of scan lines II and III can be calculated.

[0031] Step 8, as Figure 2 As shown, based on the triangulation method, given the baseline length D of the viewpoint and the two viewing angles θ1 and θ2 of scan lines II and III, the elevation difference H between the target point and the UAV's horizontal flight surface can be calculated, thus realizing UAV-borne mapping of this ground target 9.

[0032] Example:

[0033] The invention will be further described in detail below using a target elevation difference of 1000m as an example:

[0034] The front-view lens 6 is tilted forward by 24°, and the rear-view lens 7 is tilted backward by 24°, that is, θ1=θ2=24.

[0035] The scanning CCD1 has a line frequency of 72kHz. The UAV is flying in a fixed direction at a horizontal speed of 72km / h. Ground target 9 is in strip image I. a and I d The coordinates are (x a ,y a ) and (x d ,y d The baseline length D is obtained from scan lines II and III at times t2 and t1 respectively.

[0036] D=(y d -y a ) / 72000×20 (1)

[0037] The trigonometric method is used to calculate the target elevation difference H as follows:

[0038] H=D·tan24 (2)

[0039] Although the present invention has been described above with reference to the figures, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many modifications under the guidance of the present invention without departing from the spirit of the present invention, and these modifications are all within the protection scope of the present invention.

Claims

1. A UAV-borne mapping device, characterized in that, The system includes a scanning CCD (1), a registration lens (2), a digital micromirror device (3), a first reflector (4), a second reflector (5), a front-viewing lens (6), a rear-viewing lens (7), and a housing (8). The front-viewing lens (6) scans terrain information, which is reflected onto the digital micromirror device (3) via the first reflector (4). The rear-viewing lens (7) scans terrain information, which is reflected onto the digital micromirror device (3) via the second reflector (5). The digital micromirror device (3) consists of a base surface and a two-dimensional micromirror element array. The micromirror elements have on and o. The device has two flip states: when it is in the on state, the micromirror element deflects by +12°, and the ground scan strip tilts forward; when it is in the off state, the micromirror element deflects by -12°, and the ground scan strip tilts backward. The registration lens (2) is used to align the CCD pixel with the micromirror element of the digital micromirror device (3). The scanning CCD (1) consists of CCD scan line I, CCD scan line II, CCD scan line III and CCD scan line IV, which record the scan strip data. The housing (8) is used to fix the optical element and seal the optical path to prevent external interference light from entering. The optical axis intersection of the front-view lens (6) and the rear-view lens (7) is in front of the imaging point of this device; The flip state of the micromirror array of the digital micromirror device (3) is controlled, with the first and third rows in the on state and the second and fourth rows in the off state; Scan line I collects data of strip c by reflecting the data from the third row of micromirrors and the second mirror of the digital micromirror device (3); Scan line II collects data of strip a by reflecting the data from the fourth row of micromirrors and the second mirror of the digital micromirror device (3); Scan line III collects data of strip d by reflecting the data from the first row of micromirrors and the first mirror of the digital micromirror device (3); Scan line IV collects data of strip b by reflecting the data from the second row of micromirrors and the first mirror of the digital micromirror device (3). The first reflector (4) and the second reflector (5), the front-viewing lens (6) and the rear-viewing lens (7) are symmetrically arranged; the registered CCD pixels correspond one-to-one with the micromirror elements of the digital micromirror device.

2. A UAV-borne surveying method, characterized in that, The method of measuring the elevation difference of a ground target (9) using the UAV-borne mapping device as described in claim 1 includes the following steps: Step 1: Calibrate and obtain the imaging internal and external parameters of the device; The UAV flies at a certain horizontal altitude to perform four-strip scanning mapping of the ground, and the attitude data is provided by the gyroscope; Step 2: Adjust the position of the pixels of the scanning CCD (1) and the micromirror elements of the digital micromirror device (3) and the magnification of the registration lens so that one CCD pixel corresponds to one micromirror element; select four scanning lines I, II, III and IV of the CCD, which correspond to the four rows of micromirror elements of the digital micromirror device 3 respectively. Step 3: Control the flip state of the micromirror array of the digital micromirror device (3). The first and third rows are in the on state, and the second and fourth rows are in the off state. Step 4: Scan row I is reflected by the third row of micromirrors and the second mirror of the digital micromirror device (3) to collect data of strip c; Scan row II is reflected by the fourth row of micromirrors and the second mirror of the digital micromirror device (3) to collect data of strip a; Scan row III is reflected by the first row of micromirrors and the first mirror of the digital micromirror device (3) to collect data of strip d; Scan row IV is reflected by the second row of micromirrors and the first mirror of the digital micromirror device (3) to collect data of strip b. Step 5: The four CCD scan lines continuously scan the ground in one synchronous cycle, generating four strip images I. a I b I c I d ; Step Six: Image Processing - Determine the image coordinates (x, y) of the same point on the ground in the four-strip image. a ,y a ), (x b ,y b ), (x c ,y c ) and (x d ,y d ); Step 7: Select images from two imaging directions according to the measurement range. Calculate the viewpoint baseline length D of scan lines II and III based on the real-time pose distance of the gyroscope, the CCD scanning frame rate, and the coordinates of the two images. Step 8: Based on the triangulation method, given the baseline length D of the viewpoint, the viewing angle θ1 of scan line II and the viewing angle θ2 of scan line III, calculate the elevation difference H between the target point and the UAV's horizontal flight surface, and realize the UAV-borne mapping of this ground target (9).

Images