A system for treasure hunting using a small unmanned aerial vehicle (UAV)-borne ranging radar

Abstract

The present invention relates to a system for treasure hunting using a ranging radar carried by a small unmanned aerial vehicle (UAV). The system comprises the small ranging radar, a small UAV aircraft, a structural member with adjustable mounting angles, a general ground flight control computing platform, a general wireless communication platform, and positioning display software. The radar is mounted on the lower part of the UAV, with an antenna aligned with the ground plane, and a beam angle of 65° in the H-plane horizontal direction and 53° in the E-plane vertical direction. The horizontal and vertical directions of the antenna correspond to the pitch angle β and roll angle θ of the UAV, respectively. The mounting structural member is designed to be angle-adjustable, with the H-plane direction being ±32.5 degrees and 0 degrees, and the E-plane direction being ±26.5 degrees and 0 degrees. A variety of positioning methods are available according to different positioning time and accuracy requirements. The technical solution designs a treasure hunting scheme using the ranging radar carried by the small UAV. The scheme can greatly expand the treasure hunting distance, improve the treasure hunting efficiency and accuracy, and enhance the entertainment and teamwork.

Description

Technical Field

[0001] The present invention relates to a system, in particular to a system for treasure hunting using a ranging radar carried by a small unmanned aerial vehicle, and belongs to the technical field of detection systems. Background Art

[0002] In modern life, many people enjoy outdoor treasure hunting. The treasure detectors they use are traditional metal detectors, which use electromagnetic induction to determine the presence and location of metal. They are used in many fields, including military operations (mine clearance), archaeology (searching for ancient artifacts), professional treasure hunting, entertainment (finding buried objects), metal resource recovery, and metal foreign body detection in industries such as food, medicine, rubber, textiles, papermaking, chemicals, and minerals. However, traditional metal detectors have significant limitations, such as a short detection range, an inability to accurately detect objects at high speeds, and an inability to quickly and accurately locate the target. This, to a certain extent, limits their application. It is well known that electromagnetic waves can effectively penetrate materials such as plastic, rubber, glass, and ceramics, and can effectively reflect metal. Leveraging this characteristic, small ranging radars can be used to transmit and receive signals to detect the presence and location of metal targets. This provides high accuracy and can detect objects even during rapid motion. Summary of the Invention

[0003] The present invention is aimed at the problems existing in the prior art and provides a system for treasure hunting using a small unmanned aerial vehicle (UAV)-mounted ranging radar. This technical solution designs a treasure hunting motion scheme using a small unmanned aerial vehicle (UAV)-mounted ranging radar. The use of this scheme can greatly expand the scope of treasure hunting, improve treasure hunting efficiency and accuracy, and enhance entertainment and teamwork. It can be developed into an entertainment project for people, and can also be used to educate students' scientific interests, while training students' ability to use new technologies in production and life. The detection method of this scheme can be promoted and applied in many metal detection fields.

[0004] In order to achieve the above-mentioned purpose, the technical solution of the present invention is as follows: a system for treasure hunting using a small unmanned aerial vehicle (UAV)-mounted ranging radar, the system comprising a small ranging radar, a small unmanned aerial vehicle (UAV) aircraft, a structural member with adjustable mounting angle, a ground-based universal flight control computing platform, a universal wireless communication platform, and positioning display software.

[0005] The radar is installed on the lower part of the drone with the antenna aligned with the ground plane. The H-plane beam angle is 65° horizontally and the E-plane beam is 53° vertically. The H-plane corresponds to the drone's pitch angle β. By adjusting the angle of the mounting structure, one side of the H-plane beam is perpendicular to the ground, and the other side forms a 65-degree angle with the vertical line of the ground when the drone is flying parallel to the ground plane. The E-plane corresponds to the drone's roll angle θ. By adjusting the angle of the mounting structure, one side of the E-plane beam is perpendicular to the ground, and the other side forms a 53-degree angle with the vertical line of the ground when the drone is flying parallel to the ground plane. The mounting structure is designed to be angle-adjustable, with H-plane directions in ±32.5-degree and 0-degree modes, and E-plane directions in ±26.5-degree and 0-degree modes.

[0006] As an improvement of the present invention, the radar uses a 60GHz millimeter wave radar, which belongs to the 57-64GHz, unlicensed ISM band and can be used worldwide. The requirements of this radar are as follows: 1. A three-dimensional ranging range of up to 20 meters (spherical corner reflector r = 50mm); 2. An additional lens antenna is provided to adjust the beam to adapt to different applications; 3. Millimeter-level accuracy; 4. Measurement can be performed in motion and at speed; 4. Low power consumption, energy saving, environmental protection and low radiation; 5. Safe, reliable, economical and practical. Similar radar products are currently available on the market, and their antenna beams are as follows Figure 1 , the antenna airspace coverage can be changed in different applications by using lens antenna. HPBW typicalof 65(H-plane)and 53degrees(E-plane).

[0007] As an improvement of the present invention, the flight performance requirements of the UAV aircraft are as follows: flight distance ≥ 200m, flight speed ≥ 8m / s, flight time ≥ 40min, and flight altitude ≥ 20m.

[0008] Functional requirements are as follows: 1. Configure wireless Wi-Fi routing to enable data uplink and downlink. 2. In real-time formation mode, the computer software can connect to the aircraft for real-time formation, and aircraft information (battery level, coordinates, etc.) will be fed back to the computer software in real time. The entire UAV system is controlled and displayed on the ground computing platform. While uploading flight control commands, the computing software accesses and stores the aircraft's flight data, and displays the positioning results based on the corresponding positioning algorithms for different flight modes.

[0009] A method for treasure hunting using a small drone equipped with a ranging radar. The method for positioning using this system is as follows:

[0010] Step 1: Analyze the presence of a target based on the target search mode. If there is a target, is it a single target or multiple targets?

[0011] Step 2: Use different positioning methods according to different target positioning requirements.

[0012] Among them, in step 1, the H-plane direction of the antennas of the four drones is in 0-degree mode, the E-plane direction is in 0-degree mode, the antenna coverage has no overlap and the coverage edge lines of the ground coincide, and the flight altitude of a single drone is ≤20 meters, which can save the search time to the maximum extent and achieve the maximum coverage area; in step 2, the analysis is as follows: if one target is found, a relatively simple single-machine or dual-machine positioning method is used; if there are two or more targets, a three-machine or four-machine real-time positioning method is used; if the target accuracy requirement is very high, a four-machine delayed positioning method can be used.

[0013] Among them, the single-machine positioning method is as follows:

[0014] 1) Single-machine positioning method--shortest distance search method

[0015] For a single target in a certain area, the drone hovers over it until the measured distance d is the shortest, slightly greater than the distance to the ground target. At this point, the target can be located. This method is time-consuming and difficult to achieve accurate positioning. The H-plane direction is 0 degree mode, and the E-plane direction is 0 degree mode;

[0016] 2) Single machine positioning method - lifting method

[0017] A single aircraft hovers at a fixed height h1, measures the target distance d1, then descends to a height h0, measures the target distance d2, and the target is buried at a depth of d0. At this time, the distance between the target and the aircraft's projection point on the ground is x = sqrt(d1*d1-(h1+d0)*(h1+d0)) = sqrt(d2*d2-(h0+d0)*(h0+d0)); at this time, the target's buried depth d0 and the target distance x can be calculated; at this time, the target is located on a circle with a radius of x centered on the projection point, so this method can measure the burial depth and form a circular fuzzy area.

[0018] Among them, the dual-machine positioning method is as follows:

[0019] Dual-machine positioning method - plane intersection method,

[0020] When a drone targets a target in a certain area, it hovers at a fixed altitude and measures the target distance d1 and vertical height h1 from the ground. Assuming the target is buried d0 meters underground (due to competition requirements, targets are typically not buried too deep, within the shallow depth range specified by the competition), the vertical distance from the target to the drone is x1 = sqrt(d1*d1-(h1+d0)*(h1+d0)). Based on the position of the other drone, x2 can be calculated similarly as x2 = sqrt(d2*d2-(h2+d0)*(h2+d0)). Using the current positions of the two drones as the center of a circle with radii x1 and x2, two possible targets are located. This can be combined with single-drone positioning methods to remove false targets and determine the true target. The H-plane is set to 0 degrees, while the E-plane is set to 26.5 degrees for one drone and -26.5 degrees for the other. The two drones ensure that the antenna signal coverage areas generated by the H-plane and E-plane signals completely overlap.

[0021] Among them, the three-machine positioning method is as follows:

[0022] Three-aircraft positioning method - triangular formation multi-target positioning,

[0023] In this triangle formation, the lead aircraft is aircraft #1, followed by aircraft #2 and #3. Aircraft #1's H-plane is set at 32.5 degrees, while aircraft #2 and #3's is at -32.5 degrees. Aircraft #1's E-plane is set at 0 degrees, aircraft #2's at 26.5 degrees, and aircraft #3's at -26.5 degrees. The three aircraft's antenna coverage overlaps in this direction. Using this triangle formation for single-target positioning is both real-time and extremely fast, as the addition of aircraft #1 quickly eliminates the target's image. The three-aircraft positioning method can also detect multiple targets in a certain area. Assuming the flight altitude is h, the vertical distance from aircraft No. 1 to aircraft No. 2 and No. 3 is h*tan65°=2.14h, and the distance between aircraft No. 2 and No. 3 is h*tan53°=1.33h. At this time, the ground coverage of aircraft No. 1 is 2*h*tan26.5°=0.997h. Therefore, in order to overlap the coverage of aircraft No. 1 and aircraft No. 2 and No. 3, the altitude of aircraft No. 1 can only be increased, or the altitude of aircraft No. 2 and No. 3 can be lowered. The altitude of aircraft No. 1 is 1.334 times the altitude of aircraft No. 2 and No. 3.

[0024] Among them, the four-machine real-time positioning method is as follows:

[0025] Four-machine real-time positioning method - real-time positioning of rectangular detection door,

[0026] In this case, aircraft 1 is on the left of the front aircraft, aircraft 2 is on the right, and aircrafts 3 and 4 are behind. The H-plane orientation of aircrafts 1 and 2 is set to 32.5 degrees, while that of aircrafts 3 and 4 is set to -32.5 degrees. The E-plane orientation of aircrafts 1 and 3 is set to 26.5 degrees, while that of aircrafts 2 and 4 is set to -26.5 degrees. The antenna coverage areas of the four aircraft overlap. Theoretically, three-aircraft positioning can detect multiple targets. Four-aircraft positioning is used because the additional aircraft increases positioning precision and accuracy. Assuming a flight altitude of h, the distance between aircrafts 1 and 3 is h*tan65° = 2.14h, and the distance between aircrafts 2 and 4 is h*tan53° = 1.33h. This maximizes the detection gate range. Of course, the optimal flight altitude is one that accurately detects targets within the range. At this point, the antennas are installed with an elevation angle β of 65 degrees and an azimuth angle θ of 53 degrees. This formation forms an underground detection zone between the vertical distance h below the rectangular positioning gate and the radar's maximum detection range d. All four radar antennas can cover this detection zone. The detectable space is 2.14h long, 1.33h wide, and >h high.

[0027] Among them, the four-machine delayed positioning method is as follows:

[0028] Four-machine delayed positioning method - rectangular detection door delayed positioning method

[0029] This method builds on the four-machine real-time positioning method. After forming a detection plane, the system tracks the target as it descends or ascends a certain height. It then calculates the target's vertical distance from the detection gate plane (i.e., the target's burial depth coordinates) with a delay. It then calculates the target's projected position on the detection gate plane to obtain the target's two-dimensional planar position. Combining these two pieces of information yields the target's three-dimensional coordinates. By lowering the detection gate plane, this method reuses the measured data from four radars, effectively utilizing information from eight position radar sensors.

[0030] Assume that a target is detected. Radar 1 measures distance d1, while the other radars measure distances to the targets d2, d3, and d4, respectively. The target coordinates (x, y, z) are centered around the installation point of radar 1, with the target height on the z-axis. If the maximum detected height range is h0, then the target height coordinate h ranges from ground level h1 to h0. Assume the rectangular positioning gate moves a distance s. The radar target detected at this point is the same as the previously tracked reference target, so the radar target number remains unchanged. The distances detected by the four radar targets at this point can be set to d11, d21, d31, and d41. The coordinates at this point are r*r+z*z=d11*d11, where r is the distance from the target's projection on the ground plane to the origin. Combined with the equation from the previous reference time, r*r+(zs)*(zs)=d1*d1, we can calculate the z coordinate at this point, which is the target's vertical distance z from the plane of the rectangular detection gate. The distances measured by the four radars are then mapped to the detection gate plane. Based on the defuzzification principle, the x- and y-axis coordinates of the target at this point can be resolved. Similarly, if the number of detected targets is n, the number of fuzzy targets is n*n. Theoretically, as long as the detection is sufficiently accurate, only radars 1, 2, and 3 can be combined to calculate the corresponding x and y values. However, due to the frequent false alarms and missed alarms in target detection, radar 4 can participate in the redundant calculations to more accurately calculate the target's true 3D coordinates.

[0031] Compared to existing technologies, the present invention has the following advantages: 1) This technical solution, which uses drones equipped with small ranging radars for treasure hunting, creates a new form of entertainment by combining drones and radar. Compared to traditional treasure hunting, this new method has a wider detection range, higher efficiency, and greater entertainment value. It also requires more teamwork. At the same time, the popularity of this sport will allow more people to understand these radar and drone technologies, stimulate civilian demand for such military technologies, and promote the development of the third generation of the Internet - the Internet of Things. 2) This system uses drones equipped with small millimeter-wave ranging radars to perform multiple methods of locating and detecting metal targets. This solution can be applied to many metal detection fields. This method has high detection accuracy and precision, and can accurately locate the target position. Traditional methods can only detect the presence or absence of targets and determine the target position based on the target's strength. This method is generally referred to as analog signal measurement. This system uses digital radar signal measurement, which has obvious advantages and can also detect during rapid motion. Traditional methods cannot accurately detect at certain speeds. Therefore, this solution has high social value and high industrial value. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a schematic diagram of the lifting and positioning of a single machine;

[0033] Figure 2 This is a schematic diagram of the cross-positioning of two aircraft planes;

[0034] Figure 3 This is a schematic diagram of multi-target positioning for a three-plane formation;

[0035] Figure 4 Schematic diagram of the underground detection area formed by the rectangular formation;

[0036] Figure 5 The principle of radar positioning deambiguation. DETAILED DESCRIPTION

[0037] In order to deepen the understanding of the present invention, this embodiment is described in detail below with reference to the accompanying drawings.

[0038] Example 1: See Figure 1-Figure 5 A treasure hunting system using a small UAV-mounted ranging radar, the system includes a small ranging radar, a small UAV aircraft, a structural member with adjustable mounting angle, a ground-based universal flight control computing platform, a universal wireless communication platform, and positioning display software.

[0039] The radar is installed on the lower part of the drone with the antenna aligned with the ground plane. The H-plane beam angle is 65° horizontally and the E-plane beam is 53° vertically. The H-plane corresponds to the drone's pitch angle β. By adjusting the angle of the mounting structure, one side of the H-plane beam is perpendicular to the ground, and the other side forms a 65-degree angle with the vertical line of the ground when the drone is flying parallel to the ground plane. The E-plane corresponds to the drone's roll angle θ. By adjusting the angle of the mounting structure, one side of the E-plane beam is perpendicular to the ground, and the other side forms a 53-degree angle with the vertical line of the ground when the drone is flying parallel to the ground plane. The mounting structure is designed to be angle-adjustable, with H-plane directions in ±32.5-degree and 0-degree modes, and E-plane directions in ±26.5-degree and 0-degree modes.

[0040] The radar uses a 60GHz millimeter-wave radar, which belongs to the 57-64GHz, unlicensed ISM band and can be used globally. The requirements for this radar are as follows: 1. A three-dimensional ranging range of up to 20 meters (spherical corner reflector r = 50mm); 2. An additional lens antenna is provided to adjust the beam to suit different applications; 3. Millimeter-level accuracy; 4. Measurement capabilities in motion and at speed; 4. Low power consumption, energy-saving, environmentally friendly, and low radiation; 5. Safe, reliable, economical, and practical. Similar radar products are currently available on the market, and their antenna beams are as follows Figure 1 , the antenna airspace coverage can be changed in different applications by using lens antenna. HPBW is typically 65 (H-plane) and 53 degrees (E-plane).

[0041] The flight performance requirements of the UAV aircraft are as follows: flight distance ≥ 200m, flight speed ≥ 8m / s, flight time ≥ 40min, and flight altitude ≥ 20m.

[0042] Functional requirements are as follows: 1. Configure wireless Wi-Fi routing to enable data uplink and downlink. 2. In real-time formation mode, the computer software can connect to the aircraft for real-time formation, and aircraft information (battery level, coordinates, etc.) will be fed back to the computer software in real time. The entire UAV system is controlled and displayed on the ground computing platform. While uploading flight control commands, the computing software accesses and stores the aircraft's flight data, and displays the positioning results based on the corresponding positioning algorithms for different flight modes.

[0043] Example 2: See Figure 1-Figure 3 A method for treasure hunting using a small drone equipped with a ranging radar. The method for positioning using this system is as follows:

[0044] Step 1: Analyze the presence of a target based on the target search mode. If there is a target, is it a single target or multiple targets?

[0045] Step 2: Use different positioning methods according to different target positioning requirements.

[0046] Among them, in step 1, the H-plane direction of the antennas of the four drones is in 0-degree mode, the E-plane direction is in 0-degree mode, the antenna coverage has no overlap and the coverage edge lines of the ground coincide, and the flight altitude of a single drone is ≤20 meters, which can save the search time to the maximum extent and achieve the maximum coverage area; in step 2, the analysis is as follows: if one target is found, a relatively simple single-machine or dual-machine positioning method is used; if there are two or more targets, a three-machine or four-machine real-time positioning method is used; if the target accuracy requirement is very high, a four-machine delayed positioning method can be used.

[0047] Among them, the single-machine positioning method is as follows:

[0048] 1) Single-machine positioning method--shortest distance search method

[0049] For a single target in a certain area, the drone hovers over it until the measured distance d is the shortest, slightly greater than the distance to the ground target. At this point, the target can be located. This method is time-consuming and difficult to achieve accurate positioning. The H-plane direction is 0 degree mode, and the E-plane direction is 0 degree mode;

[0050] 2) Single machine positioning method - lifting method

[0051] A single aircraft hovers at a fixed height h1, measures the target distance d1, then descends to a height h0, measures the target distance d2, and the target is buried at a depth of d0. At this time, the distance between the target and the aircraft's projection point on the ground is x = sqrt(d1*d1-(h1+d0)*(h1+d0)) = sqrt(d2*d2-(h0+d0)*(h0+d0)); at this time, the target's buried depth d0 and the target distance x can be calculated; at this time, the target is located on a circle with a radius of x centered on the projection point, so this method can measure the burial depth and form a circular fuzzy area.

[0052] Among them, the dual-machine positioning method is as follows:

[0053] Dual-machine positioning method - plane intersection method,

[0054] When a drone targets a target in a certain area, it hovers at a fixed altitude and measures the target distance d1 and vertical height h1 from the ground. Assuming the target is buried d0 meters underground (due to competition requirements, targets are typically not buried too deep, within the shallow depth range specified by the competition), the vertical distance from the target to the drone is x1 = sqrt(d1*d1-(h1+d0)*(h1+d0)). Based on the position of the other drone, x2 can be calculated similarly to sqrt(d2*d2-(h2+d0)*(h2+d0)). Using the current positions of the two drones as the center of a circle with radii x1 and x2, two possible targets are located. Single-drone positioning can then be combined to remove false targets and determine the true target. The H-plane is set to 0 degrees, while one drone is set to 26.5 degrees and the other to -26.5 degrees. The two drones ensure that the antenna signal coverage areas generated by the H-plane and E-plane signals completely overlap.

[0055] Among them, the three-machine positioning method is as follows:

[0056] Three-aircraft positioning method—multi-target positioning in a triangular formation. In this case, the leading aircraft is aircraft #1, followed by aircraft #2 and #3. Aircraft #1's H-plane orientation is set to 32.5 degrees, while aircraft #2 and #3's is set to -32.5 degrees. Aircraft #1's E-plane orientation is set to 0 degrees, aircraft #2's to 26.5 degrees, and aircraft #3's to -26.5 degrees. The three aircraft's antenna coverage overlaps in this direction. This triangular formation allows for real-time single-target positioning, achieving the fastest speed, as the inclusion of aircraft #1 quickly eliminates target shadows. The three-aircraft positioning method can also detect multiple targets in a certain area. Assuming the flight altitude is h, the vertical distance from aircraft No. 1 to aircraft No. 2 and No. 3 is h*tan65°=2.14h, and the distance between aircraft No. 2 and No. 3 is h*tan53°=1.33h. At this time, the ground coverage of aircraft No. 1 is 2*h*tan26.5°=0.997h. Therefore, in order to overlap the coverage of aircraft No. 1 and aircraft No. 2 and No. 3, the altitude of aircraft No. 1 can only be increased, or the altitude of aircraft No. 2 and No. 3 can be lowered. The altitude of aircraft No. 1 is 1.334 times the altitude of aircraft No. 2 and No. 3.

[0057] Among them, the four-machine real-time positioning method is as follows:

[0058] Four-machine real-time positioning method - real-time positioning of rectangular detection door,

[0059] In this case, aircraft 1 is on the left of the front aircraft, aircraft 2 is on the right, and aircrafts 3 and 4 are behind. The H-plane orientation of aircrafts 1 and 2 is set to 32.5 degrees, while that of aircrafts 3 and 4 is set to -32.5 degrees. The E-plane orientation of aircrafts 1 and 3 is set to 26.5 degrees, while that of aircrafts 2 and 4 is set to -26.5 degrees. The antenna coverage areas of the four aircraft overlap. Theoretically, three-aircraft positioning can detect multiple targets. Four-aircraft positioning is used because the additional aircraft increases positioning precision and accuracy. Assuming a flight altitude of h, the distance between aircrafts 1 and 3 is h*tan65° = 2.14h, and the distance between aircrafts 2 and 4 is h*tan53° = 1.33h. This maximizes the detection gate range. Of course, the optimal flight altitude is one that accurately detects targets within the range. At this point, the antennas are installed with an elevation angle β of 65 degrees and an azimuth angle θ of 53 degrees. This formation forms an underground detection zone between the vertical distance h below the rectangular positioning gate and the radar's maximum detection range d. All four radar antennas can cover this detection zone. The detectable space is 2.14h long, 1.33h wide, and >h high.

[0060] Among them, the four-machine delayed positioning method is as follows:

[0061] Four-machine delayed positioning method - rectangular detection door delayed positioning method

[0062] This method builds on the four-machine real-time positioning method. After forming a detection plane, the system tracks the target as it descends or ascends a certain height. It then calculates the target's vertical distance from the detection gate plane (i.e., the target's burial depth coordinates) with a delay. It then calculates the target's projected position on the detection gate plane to obtain the target's two-dimensional planar position. Combining these two pieces of information yields the target's three-dimensional coordinates. By lowering the detection gate plane, this method reuses the measured data from four radars, effectively utilizing information from eight position radar sensors.

[0063] Assume that a target is detected. Radar 1 measures distance d1, while the other radars measure distances to the targets d2, d3, and d4, respectively. The target coordinates (x, y, z) are centered around the installation point of radar 1, with the target height on the z-axis. If the maximum detected height range is h0, then the target height coordinate h ranges from ground level h1 to h0. Assume the rectangular positioning gate moves a distance s. The radar target detected at this point is the same as the previously tracked reference target, so the radar target number remains unchanged. The distances detected by the four radar targets at this point can be set to d11, d21, d31, and d41. The coordinates at this point are r*r+z*z=d11*d11, where r is the distance from the target's projection on the ground plane to the origin. Combined with the equation from the previous reference time, r*r+(zs)*(zs)=d1*d1, we can calculate the z coordinate at this point, which is the target's vertical distance z from the plane of the rectangular detection gate. The distances measured by the four radars are then mapped to the detection gate plane. Based on the defuzzification principle, the x- and y-axis coordinates of the target at this point can be resolved. Similarly, if the number of detected targets is n, the number of fuzzy targets is n*n. Theoretically, as long as the detection is sufficiently accurate, only radars 1, 2, and 3 can be combined to calculate the corresponding x and y values. However, due to the frequent false alarms and missed alarms in target detection, radar 4 can participate in the redundant calculations to more accurately calculate the target's true 3D coordinates.

[0064] Working process: refer to Figure 5 The computing platform software commands drones to form a team or perform detection individually, calculates the detection data based on the team requirements and flight data, and measures the location of metal targets using different methods. Generally speaking, there are three types of methods, namely:

[0065] 1) Flying search method (single information positioning)

[0066] The target search is performed based on the target's distance or signal strength information until the target is reached at the position with the shortest distance or the strongest signal. This position is the target position.

[0067] 2) Real-time positioning method (two-dimensional plane positioning)

[0068] This system estimates the target's distance perpendicular to the drone based on the target's shallow depth, combined with radar-measured ground height. This distance is then projected onto the detection plane formed by the drone's radars (parallel to the ground plane). Under normal circumstances, dual-machine positioning provides real-time location information for even ambiguous targets, while three-machine positioning confirms the target's position in real time. Four-machine positioning provides redundant calculations, improving positioning accuracy and precision. The target is located at a point on the ground plane.

[0069] 3) Delayed positioning method (three-dimensional positioning)

[0070] After forming a detection plane, the system tracks the target as it descends a certain height. It then calculates the target's vertical distance from the detection gate plane (i.e., the target's burial depth coordinates) with a delay. It then calculates the target's projected position on the detection gate plane to obtain its two-dimensional position. Combining these two pieces of information yields the target's three-dimensional coordinates. This method actually utilizes information from 6-8 position radar sensors, but by lowering the detection gate plane, it reuses the measured data from 3-4 radars.

[0071] Assume that a target is detected. Radar 1 measures distance d1, while the other radars measure distances to the targets d2, d3, and d4, respectively. The target coordinates (x, y, z) are centered around the installation point of radar 1, with the target height on the z-axis. If the maximum detected height range is h0, then the target height coordinate h ranges from ground level h1 to h0. Assume the rectangular positioning gate moves a distance s. The radar target detected at this point is the same as the previously tracked reference target, so the radar target number remains unchanged. The distances detected by the four radar targets at this point can be set to d11, d21, d31, and d41. The coordinates at this point are r*r+z*z=d11*d11, where r is the distance from the target's projection on the ground plane to the origin. Combined with the equation from the previous reference time, r*r+(zs)*(zs)=d1*d1, we can calculate the z coordinate at this point, which is the target's vertical distance z from the plane of the rectangular detection gate. The distances measured by the four radars are then mapped to the detection gate plane. Based on the defuzzification principle, the x- and y-axis coordinates of the target at this point can be resolved. Similarly, if the number of detected targets is n, the number of fuzzy targets is n*n. Theoretically, as long as the detection is sufficiently accurate, only radars 1, 2, and 3 can be combined to calculate the corresponding x and y values. However, due to the frequent false alarms and missed alarms in target detection, radar 4 can participate in the redundant calculations to more accurately calculate the target's true 3D coordinates.

[0072] It should be noted that the above embodiments are not intended to limit the scope of protection of the present invention, and equivalent changes or substitutions made on the basis of the above technical solutions fall within the scope of protection of the claims of the present invention.

Claims

1. A treasure hunting system using a small drone-mounted ranging radar, characterized in that: The system includes a small ranging radar, a small UAV, a structural member with adjustable mounting angle, a ground-based general flight control computing platform, a general wireless communication platform, and positioning display software. The small ranging radar is installed on the lower part of the UAV, with the antenna aimed at the ground plane. Its beam angle H-plane is 65 degrees horizontally and E-plane is 53 degrees vertically. The H-plane corresponds to the pitch angle β of the UAV. By adjusting the angle of the mounting structure, when the UAV flies parallel to the ground plane, one side of the H-plane beam is perpendicular to the ground, and the other side forms an angle of 65 degrees with the vertical line of the ground; the E-plane is aligned with the ground plane. The mounting structure is designed to adjust the angle of the drone's roll angle θ so that when the drone flies parallel to the ground, one side of the E-plane beam is perpendicular to the ground, and the other side forms a 53-degree angle with the vertical line of the ground. The mounting structure is designed to be angle-adjustable, with the H-plane direction being ±32.5 degrees and 0 degrees, and the E-plane direction being ±26.5 degrees and 0 degrees. Target data measured by the small ranging radar is connected to the drone's flight control data and transmitted to the ground-based general flight control computing platform via a wireless communication platform. After flight search and positioning, the positioning display software provides the final multiple target positions. The radar uses a 60GHz millimeter-wave radar, which belongs to the 57-64GHz unlicensed ISM band. The radar is a multi-target ranging radar with a three-dimensional ranging range of up to 20 meters. The spherical corner reflector r = 50mm; The flight performance requirements of the small UAV aircraft are as follows: flight distance ≥ 200m, flight speed ≥ 8m / s, flight time ≥ 40min, and flight altitude ≥ 20m.

2. The treasure hunting system using a small drone-mounted ranging radar according to claim 1, characterized in that: The method for positioning using this system is as follows: Step 1: Analyze the presence of a target based on the target search mode. If there is a target, is it a single target or multiple targets? Step 2: Use different positioning methods according to different target positioning requirements; In step 1, the antenna H-plane direction of the four-way UAV is in 0-degree mode, the E-plane direction is in 0-degree mode, the antenna coverage has no overlap and the coverage edge lines on the ground coincide, and the flight altitude of a single UAV is ≤20 meters, which saves the most search time and achieves the maximum coverage area; in step 2, the analysis is as follows: if one target is found, a relatively simple single-machine or dual-machine positioning method is used; if there are two or more targets, a three-machine or four-machine real-time positioning method is used; if the target accuracy requirement is very high, a four-machine delayed positioning method is used; The single-machine positioning method is as follows: 1) Single-machine positioning method - shortest distance search method; For a single target in a certain area, the drone hovers over it until the measured distance d is the shortest, slightly greater than the distance to the ground target. At this point, the target can be located. This method is time-consuming and difficult to control accurately. The H-plane direction is 0 degree mode, and the E-plane direction is 0 degree mode; 2) Single machine positioning method - lifting method; A single aircraft hovers at a fixed height h1, measures the target distance d1, then descends to a height h0 and measures the target distance d2. The target is buried at a depth of d0. At this time, the distance from the target to the aircraft's projection point on the ground is x = sqrt(d1*d1-(h1+d0)*(h1+d0)) = sqrt(d2*d2-(h0+d0)*(h0+d0)); the target's buried depth d0 and target distance x are calculated; the target is now located on a circle with a radius of x centered on the projection point, so this method can measure the burial depth and form a circular fuzzy area. The dual-machine positioning method is as follows: Dual-machine positioning method - plane intersection method, When a drone targets a target in a certain area, it hovers at a fixed altitude and measures the target distance d1 and the vertical height h1 from the ground. Assuming the target is buried d0 meters underground, the vertical distance from the target to the drone is x1 = sqrt(d1*d1-(h1+d0)*(h1+d0)). Based on the position of the other drone, x2 is calculated similarly to sqrt(d2*d2-(h2+d0)*(h2+d0)). Using the current positions of the two drones as the center of a circle, two possible targets are located by cross-radius x1 and x2. The H-plane direction is set to 0 degrees, and the E-plane direction is set to 26.5 degrees for one drone and -26.5 degrees for the other drone. The two drones ensure that the antenna signal coverage areas generated by the H-plane and E-plane directions completely overlap. The three-machine positioning method is as follows: Three-aircraft positioning method - triangular formation multi-target real-time positioning method, At this time, the leading aircraft is No. 1 in the triangle formation, and the trailing aircraft are No. 2 and No.

3. The H-plane direction of No. 1 is 32.5 degrees, and that of No. 2 and No. 3 is -32.5; the E-plane direction of No. 1 is 0 degrees, that of No. 2 is 26.5 degrees, and that of No. 3 is -26.5 degrees; the antenna radiation areas of the three overlap on the ground plane, and the use of this triangle formation for real-time positioning of a single target is the fastest. Because the addition of No. 1 quickly removes the target mirror, the three-aircraft positioning method can be used for a certain area. It contains multiple targets for the same detection. Assuming the flight altitude is h, the vertical distance from aircraft No. 1 to aircraft No. 2 and No. 3 is h*tan65°=2.14h, and the distance between aircraft No. 2 and No. 3 is h*tan53°=1.33h. At this time, the ground coverage of aircraft No. 1 is 2*h*tan26.5°=0.997h. Therefore, in order to overlap the coverage of aircraft No. 1 and aircraft No. 2 and No. 3, the only way is to increase the altitude of aircraft No. 1 or lower the altitude of aircraft No. 2 and No.

3. The altitude of aircraft No. 1 is 1.334 times the altitude of aircraft No. 2 and No.

3.

3. The system for treasure hunting using a small drone-mounted ranging radar according to claim 2 is characterized in that The four-machine real-time positioning method is as follows: Four-machine real-time positioning method - rectangular detection door real-time positioning method, At this time, the front aircraft on the left is aircraft 1, the front aircraft on the right is aircraft 2, and the rear aircraft are aircraft 3 and 4. The H-plane direction of aircraft 1 and 2 is 32.5 degrees, and the H-plane direction of aircraft 3 and 4 is -32.5 degrees; the E-plane direction of aircraft 1 and 3 is 26.5 degrees, and the E-plane direction of aircraft 2 and 4 is -26.5 degrees. At this time, the antenna radiation areas of the four aircraft overlap on the ground plane. In theory, three aircraft positioning can detect multiple targets. The reason for using four aircraft positioning is that the additional aircraft can increase the positioning precision and accuracy. Assuming that the aircraft If the flight height is h, the distance between aircraft 1 and 3 is h*tan65°=2.14h, and the distance between aircraft 2 and 4 is h*tan53°=1.33h. At this time, the detection gate range is the largest, and the flight altitude h is based on the ability to accurately detect the target. At this time, the antenna installation pitch angle β is 65 degrees, and the azimuth angle θ is 53 degrees. This formation forms an underground detection area between the vertical distance h below the rectangular positioning gate and the maximum detection distance d of the radar. The antenna radiation of the four radars can cover this detection area. At this time, the detectable space size is length = 2.14h, width = 1.33h, and height>h.

4. The system for treasure hunting using a small drone-mounted ranging radar according to claim 3 is characterized in that The four-machine delayed positioning method is as follows: Four-machine delayed positioning method - rectangular detection door delayed positioning method, This method is based on the four-machine real-time positioning method. After forming a detection plane, the system tracks the target and then tracks it down or up to a certain height. It then calculates the vertical distance of the target from the detection gate plane (that is, the target burial depth coordinates) with a delay, and then calculates the target's projection position on the detection gate plane to obtain the target's two-dimensional plane position. The three-dimensional coordinates of the target are obtained by combining the two information. This method reuses the measured data of four radars by lowering the height of the detection gate plane, and actually uses the information of eight position radar sensors. Assume that there is a target being detected, radar 1 measures the distance d1, and the target distances measured by other radars are d2, d3, and d4 respectively. The target coordinates (x, y, z) take the installation point of radar 1 as the origin, and the target height is on the z-axis. If the maximum range of the detected height is h0, the target height coordinate h ranges from the ground height h1 to h0. Assume that the rectangular positioning door moves a distance s. The radar target received at this time is obtained by tracking the previous benchmark target, so the target number of the radar remains unchanged. The distances detected by the four radar targets at this time can be set to d11, d21, d31, and d41. The coordinates at this time are r*r+z*z=d11*d11, r is the distance of the target projected from the ground plane to the origin, and the result is: The equation at the previous reference moment is r*r+(zs)*(zs)=d1*d1, and the z coordinate at this time can be calculated, that is, the vertical distance z of the target from the rectangular detection gate plane is calculated. Then, the measured distances of the four radars are mapped to the detection gate plane. According to the defuzzification principle, the x-axis coordinate and y-axis coordinate of the target at this time can be solved. By analogy, if the number of detected targets is n, the number of fuzzy targets is n*n; theoretically, as long as the detection is accurate enough, only the combination of radars 1, 2, and 3 is needed to calculate the corresponding x and y values. Due to the existence of false alarms and missed alarms in actual target detection, radar 4 participates in redundant calculations, and the true three-dimensional coordinates of the target can be calculated more accurately.

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