WO2024222882A1 - System for detecting treasure by using miniature ranging radar carried by unmanned aerial vehicle - Google Patents

Abstract

The present invention relates to a system for detecting treasure by using miniature ranging radar carried by an unmanned aerial vehicle. The system comprises miniature ranging radar, a miniature unmanned aerial vehicle aircraft, an angle-adjustable installation structural member, a ground universal flight control computing platform, a universal wireless communication platform and positioning display software, wherein the radar is installed on a lower portion of an unmanned aerial vehicle; an antenna is aligned with the ground plane; the beam angle of the antenna in an H-plane is 65 degrees, and the beam angle of the antenna in an E-plane is 53 degrees; the horizontal direction and the vertical direction of the antenna respectively correspond to the pitch angle β and the roll angle θ of the unmanned aerial vehicle; the installation structural member is designed to be adjustable in angle; an H-plane direction is in ±32.5 degrees and 0 degree modes; and an E-plane direction is in ±26.5 degrees and 0 degree modes. According to different requirements for the positioning time and accuracy, there are various positioning methods available for selection. The technical solution designs a treasure detection activity scheme performed using the miniature ranging radar carried by the unmanned aerial vehicle; and a treasure detection distance can be greatly expanded using the solution, thereby improving the treasure detection efficiency and accuracy, and enhancing entertainment and teamwork.

Description

A system for treasure hunting using a small unmanned aerial vehicle carrying a ranging radar Technical Field

The invention relates to a system, in particular to a system for treasure hunting using a small unmanned aerial vehicle-borne ranging radar, and belongs to the technical field of detection systems.

Background Art

In modern life, many people like to engage in outdoor treasure hunting. The treasure detector they use is a traditional metal detector. The detection method is to determine the existence and location of metal through electromagnetic induction. It has been applied to military (mine clearance), archaeology (looking for ancient objects), professional treasure hunting, entertainment and leisure (looking for buried objects), metal resource recovery, and metal foreign body detection in many industries such as food, medicine, rubber, textile, papermaking, chemical industry, and ore. However, traditional metal detectors have great limitations, such as short detection distance, inability to adapt to accurate detection under high-speed motion, and inability to quickly and accurately locate the target position. Therefore, the scope of application is limited to a certain extent. As we all know, electromagnetic wave signals can effectively penetrate plastics, rubber, glass, ceramics and other materials, and can effectively reflect metal materials. Using this characteristic of electromagnetic waves, small ranging radars can be used to send and receive signals to detect the existence and location of metal targets. It has high detection accuracy and can be detected during fast motion.

Summary of the invention

The present invention aims at the problems existing in the prior art and provides a system for treasure hunting using a small unmanned aerial vehicle carrying a ranging radar. The technical solution designs a treasure hunting motion scheme using a small unmanned aerial vehicle carrying a ranging radar. The use of this scheme can greatly expand the scope of treasure hunting. The scope of this invention improves treasure hunting efficiency and accuracy, and enhances 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.

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.

Among them, the radar is installed at the bottom of the drone, and the antenna is aimed at the ground plane; its beam angle H-plane is 65° horizontally and E-plane is 53° vertically; H-plane corresponds to the drone's pitch angle β. By adjusting the angle of the installation structure, when the drone 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; E-plane corresponds to the drone's roll angle θ. By adjusting the angle of the installation structure, when the drone flies parallel to the ground plane, one side of the E-plane beam is perpendicular to the ground, and the other side forms an angle of 53 degrees with the vertical line of the ground; the installation structure is designed to be adjustable in angle, with the H-plane direction being ±32.5 degrees and 0 degrees, and the E-plane direction being ±26.5 degrees and 0 degrees.

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 the radar are as follows: 1. The three-dimensional ranging range can reach 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. It can be measured 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 already available on the market, and their antenna beams are shown in Figure 1 below, which can be Lens antennas change the antenna airspace coverage in different applications. HPBW typical of 65(H-plane)and 53 degrees(E-plane).

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.

The functional requirements are as follows: 1. Configure the wireless wifi routing function to realize data uplink and downlink; 2. In the real-time formation mode, the computer software can connect to the aircraft for real-time formation, and the aircraft information (power, coordinate information, etc.) will be fed back to the computer software in real time; the entire UAV system control and display is completed on the ground computing platform. The computing software uploads flight control instructions while accessing and storing the aircraft's flight data, and displays the positioning results according to different positioning algorithms corresponding to different flight modes.

A method for treasure hunting using a small unmanned aerial vehicle equipped with a ranging radar, and a method for positioning using the system is as follows:

Step 1: Analyze the target search mode to determine whether there is a target. 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.

Among them, in step 1, the H-plane direction of the antenna 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 of the ground coincide, and the flight altitude of a single aircraft is ≤20 meters, which can save the search time to the maximum 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.

Among them, 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 and slightly greater than the distance to the ground target. At this time, the target can be located. This method takes a long time and is 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

The 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 buried depth is d0. At this time, the distance between the target and the projection point of the aircraft on the ground is x = sqrt(d1*d1-(h1+d0)*(h1+d0)) = sqrt(d2*d2-(h0+d0)*(h0+d0)); at this time, the target 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 and the projection point as the center, so this method can measure the burial depth and form a circular fuzzy area.

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

Dual-machine positioning method--plane intersection method,

When the drone is targeting a target in a certain area, it hovers at a fixed height, measures the target distance d1, and the vertical height h1 from the ground. Assuming that the target is buried d0 meters underground (due to competition requirements, the target is usually not buried too deep, only in the shallow range specified by the competition), the vertical distance between the target position and the drone is x1 = sqrt(d1*d1-(h1+d0)*(h1+d0)); and according to the position of the other drone, x2 can be calculated in the same way as sqrt(d2*d2-(h2+d0)*(h2+d0)); then, based on the current positions of the two drones as the center of the circle, the radius x1 and x2 are cross-located to locate two possible targets. At this time, the single-machine positioning method can be combined to The real target is obtained by removing the image of the false target. The H-plane direction is in 0 degree mode, and the E-plane direction is in 26.5 degree mode for one machine and -26.5 degree mode for the other machine. The two machines ensure that the antenna signal coverage areas generated by the H-plane and E-plane directions are completely overlapped.

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

Three-aircraft positioning method-multi-target positioning in triangular formation,

At this time, the leading aircraft is aircraft No. 1 in the triangle formation, and the following aircraft are aircraft No. 2 and No. 3. The H-plane direction of aircraft No. 1 is 32.5 degrees, and aircraft No. 2 and No. 3 are -32.5; the E-plane direction of aircraft No. 1 is 0 degrees, the E-plane direction of aircraft No. 2 is 26.5 degrees, and aircraft No. 3 is -26.5 degrees; the antenna radiation areas of the three overlap in this direction. Using this triangle formation to locate a single target can be real-time, and the speed is the fastest, because the addition of aircraft No. 1 can quickly remove the target mirror. 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 plane 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.

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

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

At this time, the front left is No. 1, the front right is No. 2, and the rear are No. 3 and No. 4. The H-plane direction of No. 1 and No. 2 is 32.5 degrees, and the H-plane direction of No. 3 and No. 4 is -32.5 degrees; the E-plane direction of No. 1 and No. 3 is 26.5 degrees, and the E-plane direction of No. 2 and No. 4 is -26.5 degrees; the antenna radiation areas of the four aircraft overlap. Theoretically, the three aircraft are positioned It is possible to detect multiple targets. The reason for using four-aircraft positioning is that the additional aircraft can increase the positioning precision and accuracy. Assuming the flight altitude is 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. At this time, the detection gate range is the largest. Of course, the flight altitude is preferably that which can accurately detect the target range. 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 size of the detectable space is length = 2.14h, width = 1.33h, and height>h.

Among them, 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 the detection plane is formed, the system tracks the target to descend or rise to a certain height, and then calculates the vertical distance of the target from the detection gate plane (that is, the target burial depth coordinates), and then calculates the projection position of the target on the detection gate plane to obtain the two-dimensional plane position of the target; the three-dimensional coordinates of the target are obtained by combining the information of the two. 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 a target is 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) are based on 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, and the radar target received at this time is the same as the previous reference target tracking, so the radar target number remains unchanged. The distances detected by the four radar targets at this time can be set to d11, d21, d31, and d41. At this time, the R*r+z*z＝d11*d11, r is the distance from the projection of the target on the ground plane to the origin. Combined with the equation of the previous reference time, r*r+(zs)*(zs)＝d1*d1, the z coordinate at this time can be calculated, that is, the vertical distance z of the target from the rectangular detection gate plane. Then the measured distances of the four radars are mapped to the detection gate plane. According to the defuzzification principle, the x-axis coordinates and y-axis coordinates 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 can 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, which can more accurately calculate the true three-dimensional coordinates of the target.

Compared with the prior art, the present invention has the following advantages: 1) The design of the treasure hunting sport by using a drone equipped with a small ranging radar is to invent a new entertainment method by combining drones and radars. Compared with the traditional treasure hunting sport, the new method has a wide detection distance, high efficiency, stronger entertainment, and increased teamwork requirements. At the same time, the popularization of this sport can allow more people to understand these radar and drone technologies, stimulate the 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 a small millimeter-wave ranging radar on drones to team up to locate and detect metal targets in a variety of ways. This solution can be promoted and applied to many metal detection fields. This method has high detection accuracy and high accuracy, and can accurately locate the target position; the traditional method can only detect whether there is a target, and judge the target position by the strength of the target. This method is collectively referred to as analog signal measurement; this system uses radar signal digital measurement, which has obvious advantages, and can also be detected in fast motion. The traditional method cannot accurately detect at a certain speed. Therefore, this solution has high social value and high industrial value.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic diagram of the lifting and positioning of a single machine;

Figure 2 is a schematic diagram of the cross-positioning of two planes;

Figure 3 is a schematic diagram of multi-target positioning of a three-aircraft formation;

Figure 4 is a schematic diagram of a rectangular formation forming an underground detection area;

Figure 5 shows the radar positioning deambiguation principle.

DETAILED DESCRIPTION

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

Embodiment 1: Referring to FIG. 1-FIG 5, a system for treasure hunting using a small unmanned aerial vehicle (UAV)-mounted ranging radar is shown, wherein the system includes a small ranging radar, a small unmanned aerial vehicle (UAV) aircraft, a structural member with adjustable mounting angle, a general ground flight control computing platform, a general wireless communication platform, and positioning display software.

Among them, the radar is installed at the bottom of the drone, and the antenna is aimed at the ground plane; its beam angle H-plane is 65° horizontally and E-plane is 53° vertically; H-plane corresponds to the drone's pitch angle β. By adjusting the angle of the installation structure, when the drone 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; E-plane corresponds to the drone's roll angle θ. By adjusting the angle of the installation structure, when the drone flies parallel to the ground plane, one side of the E-plane beam is perpendicular to the ground, and the other side forms an angle of 53 degrees with the vertical line of the ground; the installation structure is designed to be adjustable in angle, with the H-plane direction being ±32.5 degrees and 0 degrees, and the E-plane direction being ±26.5 degrees and 0 degrees.

Among them, the radar uses a 60GHz millimeter wave radar, which belongs to 57-64GHz and is unlicensed The ISM band can be used worldwide. The requirements of this radar are as follows: 1. The three-dimensional ranging range can reach 20 meters (spherical corner reflector r = 50mm); 2. Additional lens antenna is provided to adjust the beam to adapt to different applications; 3. Millimeter-level accuracy; 4. It can be measured in motion and at speed; 4. Low power consumption, energy saving, environmental protection and low radiation; 5. Safe, reliable, economical and practical. There are similar radar products on the market. Its antenna beam is shown in Figure 1 below. The antenna airspace coverage can be changed in different applications through the lens antenna. HPBW typical of 65 (H-plane) and 53 degrees (E-plane).

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.

The functional requirements are as follows: 1. Configure the wireless wifi routing function to realize data uplink and downlink; 2. In the real-time formation mode, the computer software can connect to the aircraft for real-time formation, and the aircraft information (power, coordinate information, etc.) will be fed back to the computer software in real time; the entire UAV system control and display is completed on the ground computing platform. The computing software uploads flight control instructions while accessing and storing the aircraft's flight data, and displays the positioning results according to different positioning algorithms corresponding to different flight modes.

Embodiment 2: Referring to FIG. 1 to FIG. 3 , a method for treasure hunting using a small unmanned aerial vehicle equipped with a ranging radar, and a method for positioning using the system is as follows:

Step 1: Analyze the target search mode to determine whether there is a target. 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.

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

Among them, 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 and slightly greater than the distance to the ground target. At this time, the target can be located. This method takes a long time and is 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

The 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 buried depth is d0. At this time, the distance between the target and the projection point of the aircraft on the ground is x = sqrt(d1*d1-(h1+d0)*(h1+d0)) = sqrt(d2*d2-(h0+d0)*(h0+d0)); at this time, the target 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 and the projection point as the center, so this method can measure the burial depth and form a circular fuzzy area.

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

Dual-machine positioning method--plane intersection method,

When the drone is targeting a target in a certain area, it hovers at a fixed height and measures the target distance d1 and the vertical height h1 from the ground. Assuming that the target is buried d0 meters underground (due to competition requirements, the target is usually not buried too deep, only in the shallow range specified by the competition), the target The vertical ground distance from the position to the drone is x1 = sqrt(d1*d1-(h1+d0)*(h1+d0)); and according to the position of the other drone, x2 can be calculated in the same way as x2 = sqrt(d2*d2-(h2+d0)*(h2+d0)); then, based on the current positions of the two drones as the center of the circle, the radius x1 and x2 are cross-located to find two possible targets. At this time, the single-machine positioning method can be combined to remove the mirrored false target to get the real target. The H-plane direction is in 0 degree mode, and the E-plane direction is in 26.5 degree mode for one drone and -26.5 degree mode for the other. The two drones ensure that the antenna signal coverage areas generated by the H-plane and E-plane directions are completely overlapped.

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

Three-aircraft positioning method - triangular formation multi-target positioning, at this time the front aircraft is the No. 1 aircraft in the triangular formation, and the rear aircraft are No. 2 and No. 3 aircraft. The H-plane direction of No. 1 aircraft is 32.5 degrees, and No. 2 and No. 3 aircraft are -32.5; the E-plane direction of No. 1 aircraft is 0 degrees, the E-plane direction of No. 2 aircraft is 26.5 degrees, and No. 3 aircraft is -26.5 degrees; the antenna radiation areas of the three overlap in this direction. Using this triangular formation to locate a single target can be real-time positioning, and the speed is the fastest, because the addition of No. 1 aircraft can quickly remove the target mirror. 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 plane 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.

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

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

At this time, the left front machine is No. 1, the right front machine is No. 2, and the rear machines are No. 3 and No. 4. The H-plane direction of aircraft No. 2 is 32.5 degrees, and the H-plane direction of aircraft No. 3 and No. 4 is -32.5 degrees; the E-plane direction of aircraft No. 1 and No. 3 is 26.5 degrees, and the E-plane direction of aircraft No. 2 and No. 4 is -26.5 degrees; at this time, the antenna irradiation areas of the four aircraft overlap. 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 the flight altitude is h, the distance between aircraft No. 1 and No. 3 is h*tan65°＝2.14h, and the distance between aircraft No. 2 and No. 4 is h*tan53°＝1.33h. At this time, the detection gate range is the largest. Of course, the flight altitude is preferably that which can accurately detect the target range. 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 irradiation of the four radars can cover this detection area. At this time, the detectable space size is length = 2.14h, width = 1.33h, height>h.

Among them, 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 the detection plane is formed, the system tracks the target to descend or rise to a certain height, and then calculates the vertical distance of the target from the detection gate plane (that is, the target burial depth coordinates), and then calculates the projection position of the target on the detection gate plane to obtain the two-dimensional plane position of the target; the three-dimensional coordinates of the target are obtained by combining the information of the two. 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 a target is 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) are based on 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, then the target height coordinate h The range is from the ground height h1 to h0. Assuming that the rectangular positioning gate moves a distance s, the radar target received at this time is obtained by tracking the previous benchmark target, so the radar target number 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, where r is the distance from the target projected on the ground plane to the origin. Combined with the equation at the previous benchmark time, r*r+(zs)*(zs)＝d1*d1, the z coordinate at this time can be calculated, that is, the vertical distance z from the target to 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 and y-axis coordinates 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 can 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.

Working process: Referring to Figure 5, the computing platform software commands the drones to form a team or perform detection individually, calculates the detection data according to the team requirements and flight data, and measures the location of the metal target using different methods. Generally speaking, there are three types of methods, namely:

1) Flying search method (single information positioning)

The target search is performed based on the target's distance or signal strength information until the flight reaches the position where the target distance is the shortest or the signal is the strongest. This position is the target position.

2) Real-time positioning method (two-dimensional plane positioning)

This system can estimate the distance of the target perpendicular to the drone based on the shallow area where the target is buried in the ground and the actual ground height measured by the radar. According to this distance, the distances detected by multiple drone-mounted radars are projected onto the detection surface formed by the drone-mounted radars (parallel to the ground plane). Under normal circumstances, dual-machine positioning can form the position information of ambiguous targets in real time, three-machine positioning can confirm the target position in real time, and four-machine positioning can provide redundant calculations, providing positioning precision and accuracy. The target is located at a certain point on the ground plane.

3) Delayed positioning method (three-dimensional positioning)

After forming the detection plane, the system tracks the target and descends to a certain height. It then calculates the vertical distance of the target from the detection gate plane (i.e., the target burial depth coordinates) with a delay, and then calculates the projection position of the target on the detection gate plane to obtain the two-dimensional plane position of the target; the three-dimensional coordinates of the target are obtained by combining the information of the two. This method actually uses the information of 6-8 position radar sensors, and reuses the measured data of 3-4 radars by lowering the height of the detection gate plane.

Assume that a target is 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 gate moves a distance s, and 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 from the projection of the target on the ground plane to the origin, combined with the equation of the previous benchmark time r*r+(zs)*(zs)＝d1*d1, the z coordinate at this time can be calculated, that is, the vertical distance z of the target from the plane of the rectangular detection gate is calculated. Then the distances measured by the four radars are mapped to the detection gate plane. Based on the defuzzification principle, the x-axis and y-axis coordinates 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; in theory, as long as the detection is accurate enough, only the combination of radars 1, 2, and 3 is needed. The corresponding x and y values can be calculated. Due to the existence of false alarms and missed alarms in actual target detection, radar 4 participates in redundant calculations, and the real three-dimensional coordinates of the target can be calculated more accurately.

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

Claims (10)

A system for treasure hunting using a small unmanned aerial vehicle (UAV)-mounted ranging radar, characterized in that the system includes a small ranging radar, a small unmanned aerial vehicle (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, wherein the small ranging radar is installed at the bottom of the UAV, the antenna is aligned with the ground plane, and its beam angle H-plane is 65° horizontally and E-plane is 53° vertically; the H-plane corresponds to the pitch angle β of the UAV, and by adjusting the angle of the mounting structural member, when the UAV flies parallel to the ground plane, one side of the beam of the H-plane is perpendicular to the ground, and the other side forms a vertical line with the ground. The E-plane corresponds to the rolling angle θ of the UAV. By adjusting the angle of the mounting structure, when the UAV flies parallel to the ground plane, one side of the E-plane beam is perpendicular to the ground, and the other side forms an angle of 53 degrees with the vertical line of the ground. The mounting structure is designed to be adjustable in angle. The H-plane direction is ±32.5 degrees and 0 degrees, and the E-plane direction is ±26.5 degrees and 0 degrees. The target data measured by the small ranging radar is connected to the UAV flight control data, and is transmitted to the ground general flight control computing platform through the wireless communication platform. After flight search and positioning, the positioning display software gives the final multiple target positions. According to claim 1, the system for treasure hunting using a small unmanned aerial vehicle-mounted ranging radar is characterized in that the radar uses a 60GHz millimeter wave radar, which belongs to the unlicensed ISM band of 57-64GHz. The radar is a multi-target ranging radar with a three-dimensional ranging range of up to 20 meters and a spherical corner reflector r=50mm. The system for treasure hunting using a small unmanned aerial vehicle onboard ranging radar according to claim 2 is characterized in that the flight performance requirements of the small unmanned aerial vehicle are as follows: flight distance ≥ 200m, flight speed ≥ 8m/s, flight time ≥ 40min, and flight altitude ≥ 20m. The system for treasure hunting using a small unmanned aerial vehicle-mounted ranging radar according to claim 3 is characterized in that the method for positioning using the system is as follows: Step 1: Analyze the target search mode to determine whether there is a target. 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. According to the system for treasure hunting using a small unmanned aerial vehicle onboard ranging radar as described in claim 4, it is characterized in that, in step 1, the H-plane direction of the antennas of the four unmanned aerial vehicles 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, the flight altitude of a single aircraft is ≤20 meters, the search time is saved to the maximum and the maximum coverage area is achieved; in step 2, the analysis is as follows: if one target is found, a relatively simple single-machine or dual-machine positioning method is adopted; if there are two or more targets, a three-machine or four-machine real-time positioning method is adopted; if the target accuracy requirement is very high, a four-machine delayed positioning method is adopted. The system for treasure hunting using a small unmanned aerial vehicle-mounted ranging radar according to claim 5 is characterized in that the single-machine positioning method is specifically 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 and slightly greater than the distance to the ground target. At this time, the target can be located. This method takes a long time and is 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; The 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 buried depth of the target is d0. At this time, the distance between the target and the projection point of the aircraft on the ground is x = sqrt(d1*d1-(h1+d0)*(h1+d0)) = sqrt(d2*d2-(h0+d0)*(h0+d0)); at this time, the buried depth d0 of the target and the target distance x are calculated; at this time, the target is located on a circle with a radius of x and the projection point as the center, so this method can measure the buried depth and form a circular fuzzy area. The system for treasure hunting using a small unmanned aerial vehicle-mounted ranging radar according to claim 5 is characterized in that the dual-machine positioning method is specifically as follows: Dual-machine positioning method--plane intersection method, When a drone targets a target in a certain area, it hovers at a fixed height and measures the target distance d1 and the vertical height h1 from the ground. Assuming that the target is buried d0 meters underground, the vertical distance between the target position and the drone is x1 = sqrt(d1*d1-(h1+d0)*(h1+d0)); and based on the position of the other drone, x2 is calculated in the same way as x2 = sqrt(d2*d2-(h2+d0)*(h2+d0)); based on the current positions of the two drones as the center of the circle, two possible targets are cross-located with the radii x1 and x2. The H-plane direction is in 0 degree mode, and the E-plane direction is in 26.5 degree mode for one drone and -26.5 degree mode for the other. The two drones ensure that the antenna signal coverage areas generated by the H-plane and E-plane directions are completely overlapped. The system for treasure hunting using a small unmanned aerial vehicle-mounted ranging radar according to claim 5 is characterized in that the three-machine positioning method is as follows: Three-aircraft positioning method--triangle formation multi-target real-time positioning method, At this time, the front aircraft is the No. 1 aircraft in the triangle formation, and the rear aircraft are No. 2 and No. 3. The H-plane direction of No. 1 aircraft is 32.5 degrees, and that of No. 2 and No. 3 aircraft is -32.5; the E-plane direction of No. 1 aircraft is 0 degrees, that of No. 2 aircraft is 26.5 degrees, and that of No. 3 aircraft is -26.5 degrees; the antenna radiation areas of the three overlap on the ground plane, and this triangle formation is used to locate a single target in real time, which is the fastest. Because of the addition of No. 1 aircraft, the target mirror image is quickly removed. The three-aircraft positioning method can also detect multiple targets in a certain area. Assuming the flight altitude is h, the vertical distance from No. 1 aircraft to No. 2 and No. 3 aircraft is h*tan65°＝2.14h, and the distance from No. 2 and No. 3 aircraft is h*tan53°＝1.33h. At this time, the ground plane coverage of No. 1 aircraft is 2*h*tan26.5°＝0.997h, so it is necessary to overlap 1 The coverage of Unit 1 and Units 2 and 3 can only be increased by raising the height of Unit 1 or lowering the height of Units 2 and 3. The height of Unit 1 is 1.334 times the height of Units 2 and 3. The treasure hunting system using a small drone-mounted ranging radar according to claim 5 is characterized by a four-machine real-time positioning method, specifically 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 aircrafts 1 and 3 is h*tan65°=2.14h, and the distance between aircrafts 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 from the vertical distance h below the rectangular positioning gate to 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. The system for treasure hunting using a small unmanned aerial vehicle-mounted ranging radar according to claim 5 is characterized by a four-machine delayed positioning method, which is specifically 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 the system forms a detection plane, it tracks the target and then descends or rises to a certain height. It then calculates the distance of the target to the vertical detection gate plane. The method uses the measured data of four radars and the information of eight position radar sensors to obtain the three-dimensional coordinates of the target. 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 of 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, and 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.