System and method for measuring elevation of difficult mudflat area

Abstract

The invention relates to an elevation measurement system and method for a difficult mudflat area, and the system comprises an unmanned plane and an intelligent measurement rod, the unmanned plane is used for measuring the three-dimensional coordinates of the GNSS phase center and IMU data of the body in real time, carrying out the PPS time service of the system, and carrying a load for operation; the intelligent measuring rod is mounted on the unmanned aerial vehicle; the intelligent measuring rod serves as a load of the unmanned aerial vehicle, automatically measures the inclination angle of the rod body in real time and returns a measuring instruction to the unmanned aerial vehicle control unit. The method has the advantages that the unmanned aerial vehicle serves as a carrier, the load is a two-section type telescopic intelligent measuring rod, the two-section type design can ensure the flight stability of the unmanned aerial vehicle without a three-axis holder in the measuring process, the load can be conveniently installed and recycled, manual wading measurement is not needed, and the method is simple and convenient to operate. The system avoids the defects of high risk and low efficiency of traditional mud flat surveying and mapping operation, and has the advantages of high safety automation degree, low risk, high operation efficiency and the like.

Description

Technical Field

[0001] The invention belongs to the field of surveying and mapping science and technology, relates to marine surveying and mapping technology, and in particular to a system and method for measuring elevation of difficult tidal flat areas. Background Art

[0002] Elevation measurement in difficult areas such as reed marshes and tidal gullies on tidal flats has always been the focus and difficulty of tidal flat mapping. Advanced equipment such as airborne lidar or unmanned boats in this area are difficult to obtain good results. The traditional measurement method is for surveyors to use handheld GNSS-RTK to wade through water. During the process, the measurement area is mostly tidal gullies covered by dense vegetation or shallow water, so it is very difficult for manual measurement in such areas. At the same time, because the area is prone to collapse, manual measurement has safety risks such as falls and injuries.

[0003] It can be seen that the existing field of difficult tidal flat elevation measurement still lacks a safe, efficient, convenient and low-cost measurement method. In view of the flat terrain and relatively uniform vegetation height in this area, it is objectively necessary to develop an elevation measurement system for difficult tidal flat areas to overcome the shortcomings of traditional technical means and give full play to the terrain advantages and technical advantages. Summary of the invention

[0004] The purpose of the present invention is to solve the above problems existing in the prior art and to provide a system and method for measuring elevation of difficult tidal flat areas.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] A system for measuring elevation of difficult tidal flat areas, comprising:

[0007] A drone, which is used to measure the three-dimensional coordinates of its GNSS phase center, the IMU data of the fuselage and perform PPS timing on the system in real time, and to carry out operations with a load;

[0008] An intelligent measuring rod is installed on the drone; the intelligent measuring rod, as a load of the drone, automatically measures the inclination angle of the rod body in real time and returns a measurement instruction to the drone control unit module.

[0009] Preferably, the drone comprises a drone body, a battery module, a control unit module, an IMU module, a GNSS module, a first data transmission module and a belly bracket;

[0010] Among them, the battery module, the control unit module, and the IMU module are all installed in the belly of the drone fuselage; the GNSS module and the first data transmission module are installed on the top of the drone fuselage; and the belly bracket is fixedly installed on the bottom of the drone fuselage.

[0011] Preferably, the first data transmission module has a bidirectional link, and the first data transmission module can receive remote control instructions and return measurement data.

[0012] Preferably, a first data interface is provided on the belly bracket, and the first data interface is used to connect with the intelligent measuring rod and realize data transmission.

[0013] Preferably, the intelligent measuring rod comprises two sections of carbon fiber measuring rods, a length control knob, an inclination sensor, a wire, a storage unit module and an intelligent sensor.

[0014] Preferably, the two sections of carbon fiber measuring rods include a data rod and a measuring rod; wherein a bearing is provided in the middle of the data rod and the measuring rod, and the data rod and the measuring rod are connected through the bearing, and the measuring rod is provided with a length control knob for changing the length; the wire passes through the intelligent measuring rod to connect the intelligent sensor, the storage unit module and the inclination sensor on the measuring rod bearing structure housing; and finally connected to the second data interface on the belly bracket.

[0015] Preferably, the storage unit module is installed inside the data rod, and a second data interface is provided on the data rod, and the second data interface is interconnected with the first data interface to realize data exchange between the UAV and the intelligent measuring rod; the inclination sensor is installed on the outer shell of the measuring rod bearing structure, and is used to measure the angle β of the measuring rod relative to the vertical direction in real time; the intelligent sensor is installed at the bottom of the measuring rod, and is used to sense the moment when the measuring rod touches the ground, and return the touchdown signal to the UAV control unit.

[0016] Preferably, the intelligent sensor comprises a pressure sensor, a striker, a spring, an anti-slip spike, a cup-shaped tube, an anti-fall tray and an anti-winding tube;

[0017] The pressure sensor is rigidly connected to the bottom of the measuring rod, and the cup-shaped tube completely wraps the pressure sensor and is rigidly connected to the bottom of the measuring rod;

[0018] A small hole is provided at the center of the bottom of the cup-shaped tube to accommodate the passage of the striker; the striker can pass through the small hole in the middle of the bottom of the cup-shaped tube and strike the strain gauge of the pressure sensor inside;

[0019] One end of the spring is welded to the outer bottom of the cup-shaped tube, and the other end is welded to the inner bottom of the anti-fall tray. One end of the striker is welded to the center of the anti-fall tray. The striker passes through the middle of the spring and the small hole in the middle of the bottom of the cup-shaped tube. The other end of the spring is welded to the inner bottom of the anti-fall tray. The anti-slip spikes are welded to the center of the outer bottom of the anti-fall tray to prevent the anti-fall tray from sliding sideways when it contacts the mud surface. The anti-winding tube is composed of two metal tubes, one thick and one thin. One end of the thick tube is welded to the outer bottom of the cup-shaped tube, and one end of the thin tube is welded to the inside of the anti-fall tray. The other ends of the two tubes are nested in each other to form the anti-winding tube. When the anti-fall tray is not under force, the spring is completely wrapped by the anti-winding tube to prevent the spring from being entangled by vegetation during the drone's descent.

[0020] Preferably, it also includes a remote controller, in which control software and a second data transmission module are installed, and the remote controller is wirelessly connected to the drone through the control software; the second data transmission module has a bidirectional link, which can send instructions and receive measurement data and drone status data.

[0021] Preferably, it also includes a solving software, which is mainly used for solving the later data. When the flight operation is completed, the data in the storage unit module on the intelligent measuring rod is taken out and imported into the solving software for data solving;

[0022] The UAV IMU module is hard-connected to the UAV, and the three-dimensional coordinates of the phase center of the GNSS receiver of the UAV are assumed to be (x0, y0, z0). The three-axis attitude, acceleration and spatial azimuth of the intelligent measuring rod data rod at the moment of measurement are consistent with those of the UAV;

[0023] At the moment of measurement, when the inclination angle of the data pole measured by the UAV relative to the vertical direction is θ, the azimuth angle of the UAV is α, the projection distance of the phase center of the GNSS module relative to the center of the bearing structure is known to be L1, and the three-dimensional coordinates of the center of the bearing structure (x1, y1, z1) are:

[0024]

[0025] The length of the measuring rod is variable, and the length control knob is used to adjust the length according to the survey data before measurement. The length of the measuring rod is set to a fixed value L2. At the moment of measurement, when the striker just touches the pressure sensor, the UAV executes the measurement command. The angle of the measuring rod relative to the vertical direction is β, and the three-dimensional coordinates of the outer bottom of the anti-fall tray are (x x ,y x ,z z ) According to the coordinate transfer principle, the elevation value of the bottom of the anti-sinking tray is:

[0026] z z =z1-L2cosβ

[0027] The moment the drone falls to the bottom of the sinking tray, the intelligent sensor is triggered to return the measurement command. The angle between the measuring rod and the vertical direction is β, and the β angle is measured by the inclination sensor on the housing of the measuring rod bearing structure. β is theoretically a value equal to 0, then:

[0028] x x =x1,y x =y1.

[0029] Another object of the present invention is to provide a method for measuring the elevation of difficult tidal flat areas.

[0030] In order to achieve the above second purpose, the technical solution adopted by the present invention is:

[0031] A method for measuring elevation of a difficult tidal flat area, the method comprising:

[0032] S1. Data collection: Determine the scale and other parameters according to the measurement technical requirements. Collect the meteorological, hydrological, topographic data and operation requirements of the survey area, evaluate the flight environment and technical indicators on site, and determine the flight altitude, speed and other parameters;

[0033] S2, on-site survey; assess the average height of the reeds, determine the length of the measuring rod L2 according to the average height of the reeds, and set the length of L2 by the length control knob on the measuring rod;

[0034] S3, equipment preparation: connect the prepared remote controller, drone and smart measuring rod to each other;

[0035] S4, Task planning and parameter setting: Before the measurement work begins, complete the survey line planning and parameter setting on the control software in the remote controller. The parameters include the survey area scale, rod length L2 and flight altitude. The system will automatically set the measurement points and survey line spacing according to the scale.

[0036] S5, data fixation and IMU convergence: After setting the parameters, wait for the GNSS positioning data of the UAV system and the IMU data to converge so that the accuracy meets the measurement requirements;

[0037] S6, lowering measurement: the operation starts, the UAV flies along the route to the sky above the measuring point, and executes the lowering command. When the UAV is lowered to the intelligent measuring pole, the intelligent sensor touches the ground and returns the measurement command, and the UAV collects data at the same time;

[0038] S7, data recording and solving; and synchronously record all data in the storage unit of the intelligent measuring rod through the data transmission module; after the measurement of the current measuring point is completed, rise to the flight altitude, and judge whether the data meets the accuracy requirements. If it does not meet the requirements, re-execute the process of S6, otherwise the drone will fly to the next measuring point and automatically complete the measurement task of the next point; after all the measurement work is completed, the original data will be imported into the data solving software for data solving, and the result data will be output;

[0039] S8, equipment packing: After data collection is completed, the data integrity check is performed after the drone lands, and then the equipment is packed.

[0040] The advantages of the present invention are:

[0041] 1. Compared with the traditional measurement method, the present invention avoids the traditional measurement method where the surveyor holds the GNSS-RTK to perform wading operations. The drone is used as the carrier and the load is a two-stage retractable intelligent measuring rod. The two-stage design can ensure the stability of the drone's flight without a three-axis gimbal during the measurement process, and is also easy to install and recover;

[0042] 2. The present invention avoids the high risk and low efficiency of traditional elevation measurement in difficult areas of tidal flats, and has many advantages such as high degree of automation, high efficiency and low risk;

[0043] 3. The system structure of the present invention is simple. The intelligent measuring rod is directly connected to the belly bracket of the drone. It can also exchange data with the drone system while being hard-connected to the drone body. The measurement is fully automated, and the measurement data can be wirelessly transmitted back to the remote control in real time and recorded in the storage unit inside the intelligent measuring rod. There is no need for manual wading measurement, so the safety risk is low and the operation efficiency is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a structural schematic diagram of an embodiment of a system for measuring elevation of difficult tidal flat areas according to the present invention.

[0045] Figure 2 It is a module flow chart of an embodiment of a system for measuring elevation of difficult tidal flat areas according to the present invention.

[0046] Figure 3 It is a structural schematic diagram of an embodiment of the intelligent measuring rod of the present invention.

[0047] Figure 4 The present invention Figure 3 An enlarged front view and side view of an embodiment of the middle bearing structure B.

[0048] Figure 5 It is a structural schematic diagram of an embodiment of the intelligent sensor of the present invention.

[0049] Figure 6 It is a basic principle diagram of the working method of an embodiment of the solution software of the present invention.

[0050] Figure 7 It is an operation implementation diagram of an embodiment of the elevation measurement system for difficult tidal flat areas of the present invention.

[0051] Figure 8 It is a structural flow chart of an embodiment of a method for measuring elevation of difficult tidal flat areas of the present invention.

[0052] The reference numerals are as follows:

[0053] 1. UAV; 11. UAV body; 12. Battery module; 13. Control unit module;

[0054] 14. IMU module; 15. GNSS module; 16. First data transmission module;

[0055] 17. belly bracket; 171. first data interface;

[0056] 2. Intelligent measuring rod; 21. Carbon fiber measuring rod;

[0057] 211, data rod; 212, measuring rod; 213, bearing; 214, housing;

[0058] 22. tilt sensor; 23. wire; 24. storage unit module;

[0059] 25. Intelligent sensor; 251. Pressure sensor; 252. Strike pin;

[0060] 253, spring; 254, anti-slip spikes; 255, anti-fall tray; 256, anti-winding tube;

[0061] 257, cup-shaped tube; 258, small hole;

[0062] 26. Length control knob; 27. Second data interface;

[0063] 3. remote controller; 31. second data transmission module;

[0064] 4. Control software; 5. Solution software. DETAILED DESCRIPTION

[0065] In order to more clearly demonstrate the technical content of the present invention, it is further described below in conjunction with specific embodiments.

[0066] like Figure 1 , Figure 2As shown, the present invention proposes an elevation measurement system for difficult tidal flat areas, including: an unmanned aerial vehicle 1, an intelligent measuring rod 2, a remote controller 3, a control software 4 and a solution software 5, wherein the intelligent measuring rod 2 is installed on the unmanned aerial vehicle 1 as a load, the remote controller 3 establishes a wireless connection with the unmanned aerial vehicle 1 through the control software 4, and the solution software 5 is used for solving the later data; in this embodiment, the unmanned aerial vehicle 1 is the carrier of the entire system, with a payload of ≥5kg, and is mainly used to measure the three-dimensional coordinates of its GNSS phase center in real time, the IMU data of the fuselage and the PPS timing of the system, and carry the load into It specifically includes: a UAV body 11, a battery module 12, a control unit module 13, an IMU module 14, a GNSS module 15, a first data transmission module 16 and a belly bracket 17; wherein the battery module 12, the control unit module 13, and the IMU module 14 are all installed in the belly of the UAV body 11; the GNSS module 15 and the first data transmission module 16 are installed on the top of the UAV body 11 to ensure smooth data transmission and unobstructed signals; the belly bracket 17 is fixedly installed at the bottom of the UAV body 11 and is connected to the intelligent measuring rod 2.

[0067] In this embodiment, a first data interface 171 is provided on the belly bracket 17, which helps to hard-connect with the smart measuring rod data rod, and at the same time supplies power to the smart measuring rod and exchanges data; the first data transmission module 16 has a two-way link, which can receive system instructions from the remote control and return measurement data; the battery module 12 supplies power to the entire system; the GNSS module 15 is used to record the three-dimensional coordinate data of the UAV, and at the same time perform PPS timing on the system to ensure data synchronization during the measurement process; the control unit module 13 is used to control the flight of the UAV and the system control of the measurement process; the IMU module 14 is used to record the three-axis attitude, acceleration and spatial orientation (azimuth) and other data of the UAV fuselage; the above components can all access data and accept instructions from the control software in the control unit module.

[0068] like Figure 3 , Figure 4As shown, the total weight of the intelligent measuring rod 2 is ≤2kg, and it includes two sections of carbon fiber measuring rods 21, a tilt sensor 22, a wire 23, a storage unit module 24, an intelligent sensor 25 and a length control knob 26; wherein the two sections of carbon fiber measuring rods 21 include a data rod 211 and a measuring rod 212; a bearing 213 is arranged between the data rod 211 and the measuring rod 212, and the data rod 211 and the measuring rod 212 are connected through the bearing 213; in this embodiment, a second data interface 27 is also arranged on the data rod 211, and the wire 23 runs through the intelligent measuring rod 2 and connects to the second data interface 27. The second data interface 27 is connected to the data rod 211, and the intelligent sensor 25, the storage unit module 24 and the inclination sensor 22 on the outer shell of the measuring rod bearing structure are connected to realize data intercommunication; the storage unit module 24 is installed inside the data rod 211, and the second data interface 27 and the first data interface 171 can be interconnected during field operations; wherein, the length of the data rod 211 is less than the leg length of the drone to prevent it from touching the ground; the length of the measuring rod 212 can be ≥ 2 meters, and the length control knob 26 can be used to adjust the length of the measuring rod 212 according to the on-site conditions and the actual measurement scene to ensure that the length is greater than the vegetation height.

[0069] In this embodiment, the inclination sensor 22 is installed on the housing 214 of the measuring rod bearing 213 structure, and is used to measure the angle of the measuring rod 212 relative to the vertical direction in real time; the intelligent sensor 25 is installed at the bottom of the measuring rod 212, and is used to sense the moment when the measuring rod 212 touches the ground and return measurement instructions.

[0070] like Figure 5 As shown, the intelligent sensor 25 includes a pressure sensor 251, a striker 252, a spring 253, an anti-slip spike 254, an anti-sinking tray 255 and an anti-winding tube 256; wherein the pressure sensor 251 is installed at the bottom of the measuring rod 212, and a cup-shaped tube 257 completely wraps the pressure sensor 251 and is rigidly connected to the bottom of the measuring rod 212, thereby playing a role in fixing the pressure sensor 251; the striker 252 can pass through the small hole 258 in the middle of the bottom of the cup-shaped tube 257 and strike the strain gauge of the internal pressure sensor 251; the spring 253 is welded to the outer bottom of the cup-shaped tube 257, and the striker 252 is welded to the inner bottom of the anti-sinking tray 255 The center position of the cup-shaped tube is formed, and the firing pin 252 passes through the middle of the spring 253, and the other end of the spring 253 is welded to the inner bottom of the anti-falling tray; the anti-slip spike 254 is welded to the center position of the outer bottom of the anti-falling tray 255, and the anti-slip spike 254 can prevent the anti-falling tray from sliding sideways when it contacts the mud surface; in addition, two metal tubes, one thick and one thin, are respectively welded to the outer bottom of the cup-shaped tube and the inner bottom of the anti-falling tray to form an anti-winding tube 256, which is used to wrap the spring 253 to prevent the spring 253 from being entangled by vegetation during the drone's lowering process. The anti-falling tray 255 can prevent it from sinking into the mud instantly when it contacts the mud surface, thereby reducing the occurrence of measurement errors and other problems.

[0071] Specifically: when the UAV 1 reaches the measuring point and descends until the anti-fall tray 255 contacts the mud surface of the tidal flat, during the process, the bottom of the anti-fall tray 255 is subjected to an upward force and overcomes the elastic force of the spring, prompting the striker 252 to pass through the cup-shaped tube 257 and hit the strain gauge of the pressure sensor 251. The instantaneous pressure sensor 251 returns an electrical signal to the control unit module 13 of the UAV, and prompts the UAV 1 to execute the data judgment instruction. After confirming that the data is correct, the data recording is completed. At this time, all data will be recorded in the storage unit module 24; when the measurement is completed, the UAV rises, the anti-fall tray 255 leaves the ground, and is subjected to the reaction force of the spring 253. The striker 252 is separated from the strain gauge of the pressure sensor 251, waiting for the next impact on the strain gauge of the pressure sensor 251 to return the measurement instruction.

[0072] In this embodiment, a remote control 3 is provided for easy operation, and a control software 4 and a second data transmission module 31 are installed inside the remote control 3; wherein the remote control 3 mainly performs functions including parameter setting, route planning, drone status display, data display, etc., and the remote control 3 can be wirelessly connected and communicated with the drone through the control software 4, thereby avoiding the use of complex cables; the second data transmission module 31 has a two-way link, which can send instructions and receive measurement data and drone 1 status data; in particular, the input parameters of the control software 4 mainly include the flight altitude, speed, length of the measuring rod 212 and the mapping scale, wherein the mapping scale is mainly used to limit the angle of the measuring rod 212 relative to the vertical direction during the measurement process, so that it meets the requirements of Table 2 below, so that the plane accuracy of the final result meets the requirements of engineering measurement. At the same time, the mapping scale determines the spacing between the route measurement points and the measurement lines.

[0073] In this embodiment, the solving software 5 is mainly used for solving the later data. When the flight operation is completed, the data in the storage unit module 24 in the data rod 211 of the intelligent measuring rod 2 is taken out (the data can be read through a storage card or a U disk or other storage tools during the process), and imported into the solving software 5 for data solving. The solving principle is to record the measurement time, three-dimensional coordinates, IMU module 14 data, inclination sensor 22 data, and the length of the measuring rod 212, so as to calculate the elevation of the mud surface.

[0074] The principle of the present invention is as follows: the present invention is composed of a drone 1 and a load intelligent measuring rod 2, the first data interface 171 of the drone 1 is fixedly connected to the second data rod interface 27 of the intelligent measuring rod, the drone has an IMU module 14, which can measure the three-axis attitude, acceleration and spatial orientation (azimuth) of the drone 1 in real time, and serve as the three-axis attitude, acceleration and spatial orientation (azimuth) of the data rod 211 of the intelligent measuring rod; the inclination sensor 22 on the measuring rod 212 of the intelligent measuring rod can measure the inclination angle of the measuring rod in real time, the data rod 211 and the measuring rod 212 are connected by a bearing structure, and the center of the bearing 213 structure is used as the intersection of the two; the GNSS module 15 in the drone can measure the three-dimensional coordinates of its phase center in real time, and through two coordinate transfers, the real-time three-dimensional coordinates of the anti-sinking tray 255 at the bottom of the measuring rod are solved; at the same time, the high-precision clock of the GNSS module 15 performs system pulse timing (PPS), and transmits the clock PPS signal to each other component through the GNSS receiver, thereby maintaining the synchronization of the time of each module.

[0075] Specifically:

[0076] like Figure 6 As shown, when the three-dimensional coordinates of the phase center of the GNSS module 15 receiver of the drone 1 are (x0, y0, z0), the IMU module 14 in the drone 1 is rigidly connected to the drone 1, and the three-axis attitude, acceleration and spatial orientation (azimuth) of the smart measuring rod data rod 211 are consistent with those of the drone 1;

[0077] Assume that during measurement, the inclination angle of the data rod 211 relative to the vertical direction is θ and the azimuth is α measured by the three-axis attitude of the drone 1, the distance between the phase center of the GNSS module 15 and the center of the bearing structure is known to be L1, the three-dimensional coordinates of the phase center of the GNSS module 15 receiver during measurement are (X0, Y0, Z0), and the three-dimensional coordinates of the center of the bearing 213 structure are (X1, Y1, Z1), then:

[0078]

[0079] The length of the measuring rod 212 is obtained by surveying before the measurement. The length of the measuring rod 212 is set to L2. When the striker 252 just touches the pressure sensor 251, the drone 1 executes the measurement command at the moment. According to the coordinate transmission, the bottom elevation value of the anti-fall tray 255 is:

[0080] z z =z1-L2cosβ

[0081] Since the moment the drone 1 falls to the bottom of the sinking tray 255, the intelligent sensor is triggered to return the measurement command, so it is assumed that the angle between the measuring rod and the vertical direction is β at this time. The β angle is measured by the inclination sensor on the housing of the bearing structure of the measuring rod, which is a value equal to 0 in theory. At this time:

[0082] x x =x1,y x =y1

[0083] However, in actual production, considering wind resistance, vegetation resistance and other issues, it is difficult to make the β angle equal to 0. According to the Engineering Survey Standard GB 50026-2020, for flat and hilly land, the plane point error should not be greater than 0.6mm on the map. The plane requirements of different scales are shown in Table 1:

[0084] Table 1 Engineering "Engineering Measurement Standard GB 50026-2020" Plane Error

[0085] scale 1：500 1：1000 1：2000 Plane error 0.3m 0.6m 1.2 m

[0086] From Table 1, it is known that the total length of the measuring rod is set to L2 at the moment of measurement, then β MAX The angle can be limited according to different scales, so the smart sensor measures the rod β MAX As shown in Table 2:

[0087] Table 2 Maximum value β of the angle between the measuring rod and the vertical direction according to the standard MAX scope

[0088]

[0089] So, when 0≤β<β MAX When x x =x1,y x =y1, when β≥β MAX When β<β, the current measurement data is invalid, and the drone re-executes the ascent and descent process and re-measures until 0≤β<β MAX ,so:

[0090]

[0091] It should be noted that: the present invention uses a drone as a carrier, and the load is a two-stage (divided into a data rod and a measuring rod) retractable intelligent measuring rod. The two-stage design can ensure the stability of the drone's flight without a three-axis gimbal during the measurement process, and is also convenient for the installation and recovery of the drone. When the present invention does not execute a measurement command, the drone maintains a safe altitude for constant speed cruising until the horizontal speed drops to 0 when the measuring point is reached. At the same time, the drone is lowered to the anti-fall tray at the bottom of the intelligent measuring rod in accordance with the instructions uploaded in the remote control to contact the mud surface. The striker is instantly subjected to an upward force to hit the strain gauge of the pressure sensor. At this time, the pressure sensor returns the measurement instruction to the drone main control. The drone records the measurement time, three-dimensional coordinates, IMU data, inclination sensor data and other data at this time, and transmits the above data information back to the drone remote control and records it in the storage unit inside the intelligent measuring rod. This solution avoids the high risk and low efficiency of traditional elevation measurement in difficult tidal flat areas, and has many advantages such as high degree of automation, high efficiency and low risk.

[0092] Secondly, the system structure of the present invention is simple. The intelligent measuring rod is directly connected to the belly bracket of the drone. While being hard-connected to the drone body, it can also exchange data with the drone system. The measurement is fully automated, and the measurement data can be wirelessly transmitted back to the remote control in real time and recorded in the storage unit inside the intelligent measuring rod, without the need for manual wading measurement.

[0093] In addition, in order to measure the three-axis attitude, acceleration, and spatial orientation (azimuth) of the intelligent measuring rod, the present invention designs the measuring rod of the intelligent measuring rod to be hard-connected with the drone, and does not require a separate drone gimbal design; the intelligent measuring rod does not have a separate IMU module installed, and the elevation is calculated only by recording the angle of the inclination sensor relative to the vertical direction. The plane coordinates are limited to the error range required in Table 1 according to the existing "Engineering Measurement Standard GB 50026-2020". Figure 1 The range of the β angle: 0≤β<β MAX， Thereby limiting the error range of the plane coordinates; generally speaking, the height of the reeds on the tidal flat is relatively uniform, which is conducive to the operation of the present invention.

[0094] like Figure 7 and Figure 8 As shown, the present invention also provides a method for measuring elevation of difficult tidal flat areas, the method comprising:

[0095] S1. Data collection: Determine the scale and other parameters according to the measurement technical requirements. Collect the meteorological, hydrological, topographic data and technical requirements of the survey area, evaluate the flight environment and technical indicators on site, and determine the flight speed and other parameters;

[0096] S2, on-site survey; assess the average height of reeds. The tidal flat vegetation is generally dominated by reeds and Spartina alterniflora. Generally speaking, the height is relatively uniform, which is conducive to the measurement operation of the present invention. Therefore, the present method has high reliability. Before the formal start, the approximate height of the reeds is determined by a tape measure or a GNSS manual operation method. The length of the measuring rod L2 is determined according to the height of the reeds. Multiple point measurements are performed, and the length of the rod length L2 is determined according to the average height of the reeds. When the height difference of the vegetation is too large, a zoning operation is performed;

[0097] S3, equipment preparation: connect the prepared remote controller, drone and smart measuring rod to each other;

[0098] S4. Task planning and parameter setting: Before the measurement work begins, use the control software in the remote controller to complete the survey line planning and parameter setting. The parameters include the survey area scale, flight speed, measuring rod length L2 and flight altitude. The system will automatically set the measurement points and survey line spacing according to the scale.

[0099] S5, GNSS data and IMU convergence; After setting the parameters, wait for the GNSS positioning data and IMU data of the UAV system to converge so that the accuracy meets the measurement requirements;

[0100] S6, descending measurement: The UAV flies along the flight altitude to hover above the measuring point, then descends. When it lands on the intelligent measuring rod, the sensing head touches the ground and triggers the sensor to return the measurement command to the UAV, starting the data measurement work, and synchronously recording the current measurement time and three-dimensional coordinates. Combined with the IMU data, the tilt sensor data β, the measuring rod length L2 and other information, the UAV data transmission module sends it back to the remote control and records it in the storage unit of the intelligent measuring rod. When β ≥ β MAX When β<β, the measurement data of the measuring point is invalid, and the UAV re-executes the ascent and descent process until 0≤β<β MAX And record, and fly to the next measuring point to automatically complete the height measurement of the next point;

[0101] S7, data recording and data solving; after completion, the original data is imported into the data solving software and the data solving is performed;

[0102] S8. After data collection is completed, the drone is inspected after landing and the equipment is packed.

[0103] The above-mentioned related explanations and descriptions of the embodiments are for the convenience of those skilled in the art to understand and apply the present invention. It is obvious that those familiar with the art can easily make various modifications to these contents and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above-mentioned related explanations and descriptions of the embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the protection scope of the present invention.

Claims

1. A system for measuring elevation in difficult tidal flat areas, characterized in that: include: A drone, which is used to measure the three-dimensional coordinates of its GNSS phase center in real time, the IMU data of the drone body and perform PPS timing on the system, and carry out operations with a load; An intelligent measuring rod is installed on the drone; the intelligent measuring rod serves as a load of the drone, automatically and in real time measures the angle of the rod body relative to the vertical direction and returns a measurement instruction to the drone control unit module.

2. The elevation measurement system for difficult tidal flat areas according to claim 1 is characterized in that: The drone includes a drone body, a battery module, a control unit module, an IMU module, a GNSS module, a first data transmission module and a belly bracket; Among them, the battery module, the control unit module, and the IMU module are all installed in the belly of the drone; the GNSS module and the first data transmission module are installed on the top of the drone body; the belly bracket is fixedly installed on the bottom of the drone body and connected to the intelligent measuring rod.

3. The elevation measurement system for difficult tidal flat areas according to claim 2 is characterized in that: The first data transmission module has a bidirectional link, and the first data transmission module can receive system instructions of the remote controller and return measurement data.

4. The elevation measurement system for difficult tidal flat areas according to claim 2 is characterized in that: The belly bracket is provided with a first data interface, and the first data interface is used to connect with the intelligent measuring rod and realize data transmission.

5. The elevation measurement system for difficult tidal flat areas according to claim 4 is characterized in that: The intelligent measuring rod comprises two sections of carbon fiber rods, a length control knob, an inclination sensor, a wire, a storage unit module and an intelligent sensor; The two sections of carbon fiber rods include a data rod and a measuring rod; wherein a bearing is provided between the data rod and the measuring rod, and the data rod and the measuring rod are connected via the bearing, and a length control knob for changing the length is provided on the measuring rod; The wire passes through the intelligent measuring rod to connect the intelligent sensor, the storage unit module and the inclination sensor on the measuring rod bearing structure shell, and is finally connected to the first data interface on the belly bracket.

6. The elevation measurement system for difficult tidal flat areas according to claim 5 is characterized in that: The storage unit module is installed inside the data rod and is used to store the raw measurement data in real time; the data rod is provided with a second data interface, and the second data interface is interconnected with the first data interface to realize data exchange between the drone and the smart measurement rod; The inclination sensor is installed on the housing of the measuring rod bearing structure and is used to measure the angle of the measuring rod relative to the vertical direction in real time; The intelligent sensor is installed at the bottom of the measuring rod, and is used to sense the moment when the measuring rod touches the ground, and return a touchdown signal to the drone control unit module.

7. The elevation measurement system for difficult tidal flat areas according to claim 6 is characterized in that: The intelligent sensor includes a pressure sensor, a striker, a spring, an anti-slip spike, a cup-shaped tube, an anti-fall tray and an anti-winding tube; The pressure sensor is rigidly connected to the bottom of the measuring rod, and the cup-shaped tube completely wraps the pressure sensor and is rigidly connected to the bottom of the measuring rod; A small hole is provided in the middle of the bottom of the cup-shaped tube to accommodate the passage of the striker; the striker can pass through the small hole in the middle of the bottom of the cup-shaped tube and strike the strain gauge of the pressure sensor inside; One end of the spring is welded to the outer bottom of the cup-shaped tube, and the other end is welded to the inner bottom of the anti-fall tray. One end of the striker is welded to the center of the inner bottom of the anti-fall tray. The striker passes through the middle of the spring and the small hole in the middle of the bottom of the cup-shaped tube. The anti-slip spikes are welded at the center position of the outer bottom of the anti-fall tray, which can prevent the anti-fall tray from sliding sideways the moment it contacts the mud surface; the anti-winding tube is composed of two metal tubes, one thick and one thin, one end of the thick tube is welded to the outer bottom of the cup-shaped tube, and one end of the thin tube is welded to the inner bottom of the anti-fall tray, and the other ends of the two tubes are nested in each other to form the anti-winding tube, and when the anti-fall tray is not under force, the spring is completely wrapped by the anti-winding tube to prevent the spring from being entangled by vegetation during the drone's descent.

8. The system for measuring elevation of difficult tidal flat areas according to any one of claims 1 to 7, characterized in that: It also includes a remote controller, which has control software and a second data transmission module installed inside. The remote controller is wirelessly connected to the drone through the control software; the second data transmission module has a bidirectional link, which can send instructions and receive measurement data and drone status data.

9. The system for measuring elevation of difficult tidal flat areas according to any one of claims 1 to 7, characterized in that: It also includes a solving software, which is mainly used for solving the later data. When the flight operation is completed, the data in the storage unit module on the intelligent measuring rod is taken out and imported into the solving software for data solving; The UAV IMU module is hard-connected to the UAV, and the three-dimensional coordinates of the phase center of the GNSS receiver of the UAV are assumed to be (x0, y0, z0). The three-axis attitude, acceleration and spatial azimuth of the intelligent measuring rod data rod at the moment of measurement are consistent with the UAV; At the moment of measurement, assuming that the inclination angle of the data pole measured by the drone relative to the vertical direction is θ, the azimuth angle of the drone is α, the distance between the phase center of the GNSS module and the center of the bearing structure is known to be L1, and the three-dimensional coordinates of the center of the bearing structure (x1, y1, z1) are: The length of the measuring rod is variable, and the length control knob is used to adjust the length according to the survey data before measurement. The length of the measuring rod is set to a fixed value L2. At the moment of measurement, when the striker just touches the pressure sensor, the UAV executes the measurement command. The angle of the measuring rod relative to the vertical direction is β, and the three-dimensional coordinates of the outer bottom of the anti-fall tray are (x x ,y x ,z z ) According to the coordinate transfer principle, the elevation value of the bottom of the anti-sinking tray is: With z =z1-L2cosβ When the drone falls to the bottom of the sinking tray, the intelligent sensor is triggered to return the measurement command. The angle between the measuring rod and the vertical direction is β, and the β angle is measured by the inclination sensor on the housing of the bearing structure of the measuring rod. Theoretically, β should be a value equal to 0, then: x x =x1,y x =y1。 10. A method for measuring elevation in difficult tidal flat areas, characterized in that: The method is based on the elevation measurement system for difficult tidal flat areas according to claim 1, and the method comprises: S1. Data collection: According to the measurement technical requirements, determine the scale and other parameters, collect the meteorological, hydrological, topographic data and operation requirements of the survey area, evaluate the flight environment and technical indicators on site, and determine the flight speed and other parameters; S2, on-site survey; assess the average height of the reeds, determine the length of the measuring rod L2 according to the average height of the reeds, and set the length of L2 by the length control knob on the measuring rod; S3, equipment preparation: connect the prepared remote controller, drone and smart measuring rod to each other; S4, Task planning and parameter setting: Before the measurement work begins, complete the survey line planning and parameter setting on the control software in the remote controller. The parameters include the survey area scale, flight speed, rod length L2 and flight altitude. The system will automatically set the measurement points and survey line spacing according to the scale. S5, GNSS data and IMU convergence: After setting the parameters, wait for the GNSS positioning data and IMU data of the drone system to converge so that the accuracy meets the measurement requirements; S6, lowering measurement: the operation starts, the UAV flies along the route to the sky above the measuring point, and executes the lowering command. When the UAV drops to the height of the intelligent sensor on the intelligent measuring pole, it touches the ground and returns the measurement command, and the UAV collects data at the same time; S7, data recording and solving; and synchronously record all data in the storage unit of the intelligent measuring rod through the data transmission module; after the measurement of the current measuring point is completed, rise to the flight altitude, and judge whether the data meets the accuracy requirements. If it does not meet the requirements, re-execute the process of S6, otherwise the drone will fly to the next measuring point and automatically complete the measurement task of the next point; after all the measurement work is completed, the original data will be imported into the data solving software for data solving, and the result data will be output; S8, equipment packing: After data collection is completed, the drone is landed to perform a data integrity check, and then the equipment is packed.

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