Polar region shipborne unmanned aerial vehicle high-precision positioning method and system

Abstract

The invention provides a polar region shipborne unmanned aerial vehicle high-precision positioning method and system, and the method comprises the steps: deploying a radio base station at a ship end, determining the positioning of the base station in real time, carrying out the real-time wireless communication, carrying out the distance measurement, and recording the timestamp of a communication signal; the unmanned aerial vehicle measures the height information relative to the ground in real time through a laser altimeter, and then the ship-end computer calculates the accurate distance between the unmanned aerial vehicle and each radio base station based on a flight time method; the ship-end computer receives and processes the radio distance data, the height data of the laser altimeter and the differential RTK positioning data in real time, and a linear equation elimination method is adopted to calculate the three-dimensional coordinates of the unmanned aerial vehicle; according to the continuous three-dimensional coordinate data of the unmanned aerial vehicle, the real-time horizontal speed and the flight direction of the unmanned aerial vehicle are obtained through differential calculation; and converting the calculated position information and the real-time speed and direction information into longitude and latitude height positioning information, and sending the longitude and latitude height positioning information to an unmanned aerial vehicle navigation control system in real time. According to the invention, the positioning precision and navigation stability of the shipborne unmanned aerial vehicle in a complex environment are effectively improved.

Description

Technical Field

[0001] This invention relates to the field of unmanned aerial vehicle (UAV) positioning technology, specifically to a high-precision positioning method and system for shipborne UAVs in polar regions. More particularly, it relates to a high-precision positioning method for shipborne UAVs in polar regions based on a combination of radio ranging and laser altimeter. Background Technology

[0002] In existing technologies, shipborne UAVs typically rely on a single GPS signal for location determination. However, GPS signals are susceptible to environmental factors and severe weather, leading to a significant decrease in accuracy or even loss of signal strength. Furthermore, during polar expeditions, GPS satellite acquisition is limited in certain high-latitude regions, failing to provide accurate positioning for UAVs and impacting flight safety and mission performance. Simultaneously, relying solely on GPS positioning cannot accurately calculate the UAV's real-time horizontal speed and flight direction, resulting in insufficient navigation and control precision during complex missions and increasing operational risks.

[0003] Patent document CN117849777A discloses a method, device, electronic device, and storage medium for positioning and navigation of a shipborne unmanned aerial vehicle (UAV), comprising: acquiring radar images using a radar mounted on the shipborne UAV; obtaining target detection results based on the radar images, the target detection results including target geometric parameters; acquiring target state information based on the target detection results using an extended Kalman filter and a continuous white noise acceleration model, the target state information including a target length measurement; and acquiring positioning and navigation information of the shipborne UAV based on the target state information using a state estimation Kalman filter.

[0004] However, the method in patent document CN117849777A cannot determine the direction and position of the UAV itself in the ship's coordinate system.

[0005] Therefore, there is an urgent need in the market to develop a high-precision positioning technology to effectively overcome the limitations of GPS as a single method, improve the stability and safety of UAVs in complex environmental conditions, and ensure the accurate navigation and efficient mission execution capabilities of shipborne UAVs during Arctic and Antarctic scientific expeditions. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this invention is to provide a high-precision positioning method and system for shipborne unmanned aerial vehicles (UAVs) in polar regions.

[0007] A high-precision positioning method for shipborne unmanned aerial vehicles in polar regions, provided by the present invention, includes:

[0008] Step S1: Deploy a radio base station at the ship's end and determine the base station's location in real time;

[0009] Step S2: The UAV is equipped with wireless equipment and a laser altimeter sensor. It conducts distance measurement by communicating wirelessly with the ship's radio base station in real time via a fixed frequency and records the timestamp of the communication signal.

[0010] Step S3: The UAV measures its altitude relative to the ground in real time using a laser altimeter;

[0011] Step S4: The radio base station and shipboard computer receive and process the radio ranging data and laser altimeter height data transmitted back from the UAV in real time.

[0012] Step S5: The shipboard computer calculates the precise distance between the UAV and each radio base station based on the time-of-flight method;

[0013] Step S6: The shipboard computer receives and processes radio distance data, laser altimeter height data, and differential RTK positioning data in real time, and uses the linear equation elimination method to calculate the three-dimensional coordinates of the UAV.

[0014] Step S7: Based on the continuous UAV three-dimensional coordinate data, obtain the UAV's real-time horizontal speed and flight direction through differential calculation;

[0015] Step S8: Convert the calculated position information and real-time speed and direction information into latitude, longitude and altitude positioning information, and send it to the UAV navigation and control system in real time.

[0016] Preferably, in step S2, the UAV is equipped with a wireless device that matches the frequency of the base station. The UAV actively sends a radio ranging signal to the base station at a fixed frequency and receives the feedback signal from the base station in real time. Then, the wireless device records the signal transmission and reception timestamps in real time.

[0017] Preferably, step S4 includes:

[0018] Step S4.1: The radio base station receives the radio signals transmitted by the UAV in real time and records the accurate reception timestamp t. r ;

[0019] Step S4.2: The ship's computer receives the UAV ranging timestamp data t relayed from the radio base station. s The data includes the altitude data H transmitted in real time by the UAV laser altimeter, and the data is preprocessed to eliminate significant errors and noise.

[0020] Preferably, step S5 includes:

[0021] Step S5.1: Calculate the round-trip flight time Δt of the radio signals from the UAV to each base station based on the timestamps of radio signal transmission and reception;

[0022] Step S5.2: Calculate the precise distance between the UAV and each radio base station in real time using the Time-of-Flight (TOF) method, as shown in the following formula:

[0023]

[0024] Among them, D i Let represent the distance from the drone to the i-th base station, and c represent the speed of radio signal propagation, which is the speed of light (3 × 10⁻⁶). 8 m / s, The timestamp indicating the time of the drone's radio signal transmission. This represents the timestamp when the i-th base station receives the radio signal;

[0025] Step S5.3: After real-time verification and filtering of the distance data, output it to the next calculation stage.

[0026] Preferably, step S6 includes:

[0027] Step S6.1: Receive the signal reception timestamp recorded by the radio base station and the laser altimeter height data transmitted by the UAV, perform preliminary preprocessing and error elimination on the data, and store it in a standardized format;

[0028] Step S6.2: Construct a system of three-dimensional spatial nonlinear equations with reference to the base station location, as shown in the following formulas:

[0029]

[0030] Among them, (X) i ,Y i Z i () represents the coordinates of the i-th base station;

[0031] Step S6.3: Eliminate higher-order terms of the equation using the elimination method, simplifying the equation to a linear form, as shown below:

[0032] AX = B

[0033] Where A represents the coefficient matrix composed of the coordinates of each base station, X represents the three-dimensional coordinate matrix of the UAV to be determined, and B represents the constant term matrix composed of ranging data;

[0034] Step S6.4: Solve the system of linear equations to obtain the real-time and accurate three-dimensional spatial coordinates of the UAV.

[0035] Preferably, the preprocessing and error elimination includes removing obvious abnormal data and eliminating significant errors caused by signal interference or equipment errors;

[0036] Filtering algorithms such as median filtering, Kalman filtering, or moving average filtering are used to remove abnormal raw data, suppress noise, and store the preprocessed data in a standard format.

[0037] Preferably, step S7 includes:

[0038] Step S7.1: Record the continuous three-dimensional spatial coordinates of the UAV in real time;

[0039] Step S7.2: Perform differential calculation on the continuous three-dimensional coordinate data to obtain the UAV's velocity vector. The calculation formula is as follows:

[0040]

[0041] Where Δt is the time interval between two consecutive data samplings, ΔX, ΔY, and ΔZ represent the displacement differences of the UAV along the X-axis, Y-axis, and Z-axis within the time interval Δt, respectively, and V x V y V z These represent the velocity components of the UAV in the X, Y, and Z axes, respectively.

[0042] Step S7.3: Calculate the real-time horizontal velocity and flight direction of the UAV based on the velocity vector, using the following formula:

[0043]

[0044]

[0045] Among them, V hor θ represents the horizontal speed of the drone, and θ represents the flight direction angle of the drone.

[0046] Preferably, step S8 includes the ship end integrating and encapsulating the position and speed information into latitude, longitude, and altitude positioning data, which is then transmitted to the UAV in real time via wireless equipment; the UAV navigation system receives this data in real time and uses it as the basis for its own navigation and flight control.

[0047] The encapsulated positioning information includes the UAV's real-time latitude and longitude coordinates, altitude, speed, heading angle, and UTC timestamp.

[0048] A high-precision positioning system for shipborne unmanned aerial vehicles in polar regions, provided by the present invention, includes:

[0049] Module M1: Deploys a radio base station at the ship's bow and determines the base station's location in real time;

[0050] Module M2: The UAV is equipped with wireless equipment and a laser altimeter sensor. It conducts distance measurement through real-time wireless communication with the ship's radio base station at a fixed frequency and records the timestamp of the communication signal.

[0051] Module M3: The UAV uses a laser altimeter to measure its altitude relative to the ground in real time;

[0052] Module M4: The radio base station and shipboard computer receive and process radio ranging data and laser altimeter height data transmitted back from the UAV in real time;

[0053] Module M5: The shipboard computer calculates the precise distance between the UAV and each radio base station based on the time-of-flight method;

[0054] Module M6: The shipboard computer receives and processes radio distance data, laser altimeter height data, and differential RTK positioning data in real time, and uses the linear equation elimination method to calculate the UAV's three-dimensional coordinates.

[0055] Module M7: Based on continuous UAV 3D coordinate data, it obtains the UAV's real-time horizontal speed and flight direction through differential calculation;

[0056] Module M8: Converts the calculated position information and real-time speed and direction information into latitude, longitude, and altitude positioning information, and sends it to the UAV navigation and control system in real time.

[0057] Preferably, in module M2, the UAV is equipped with a wireless device that matches the frequency of the base station. The UAV actively sends radio ranging signals to the base station at a fixed frequency and receives feedback signals from the base station in real time. Then, the wireless device records the signal transmission and reception timestamps in real time.

[0058] Compared with the prior art, the present invention has the following beneficial effects:

[0059] This invention effectively improves the positioning accuracy and navigation stability of shipborne UAVs in complex environments, especially meeting the high-precision autonomous navigation and flight control requirements of shipborne UAVs at sea, and greatly improving the safety and reliability of mission execution. Attached Figure Description

[0060] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0061] Figure 1 This is a schematic diagram of the high-precision positioning method for unmanned aerial vehicles (UAVs) according to an embodiment of the present invention;

[0062] Figure 2 This is a flowchart illustrating an example of how the present invention calculates the location of a UAV using a shipborne base station and radio technology.

[0063] Figure 3 This is a flowchart of the UAV positioning data fusion and calculation process according to an embodiment of the present invention;

[0064] Figure 4 This is a schematic diagram of the structure of the shipborne unmanned aerial vehicle high-precision positioning system of the present invention. Detailed Implementation

[0065] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0066] A high-precision positioning method for shipborne unmanned aerial vehicles in polar regions, as provided by the present invention, is as follows: Figure 1 As shown, it includes:

[0067] Step S1: Deploy radio base stations at the ship's bow and determine their real-time location. Deploy long-range radio base stations in the 915MHz band at multiple specific locations on the ship, and use shipborne differential RTK to determine the base station coordinates in real time. Transmit the base station location data to the ship's computer for storage and processing. Using shipborne differential RTK (Real-Time Kinematic) equipment, the ship's computer performs real-time measurement and positioning of the coordinates of each radio base station to provide a high-precision positioning reference.

[0068] Step S2: The UAV, equipped with wireless equipment and a laser altimeter sensor, conducts real-time wireless communication with the ship's radio base station via a fixed frequency to measure distance and records the timestamps of the communication signals. The UAV's wireless equipment is frequency-matched with the base station. The UAV actively sends radio ranging signals to the base station at a fixed frequency and receives feedback signals from the base station in real time. The wireless equipment then records the timestamps of signal transmission and reception in real time to provide the basic data for ranging calculation.

[0069] Step S3: The UAV measures its altitude relative to the ground in real time using a laser altimeter. Step S3 includes installing a laser altimeter sensor on the bottom of the UAV. The laser altimeter sensor continuously emits laser pulses at a fixed frequency and receives the laser pulse signals reflected from the ground in real time, calculating the time of flight (TOF) of the laser pulses in real time to obtain accurate altitude data of the UAV relative to the ground.

[0070] Step S4: The radio base station and shipboard computer receive and process in real time the radio ranging data and laser altimeter height data transmitted back from the UAV. Step S4 includes:

[0071] Step S4.1: The radio base station receives the radio signals transmitted by the UAV in real time and records the accurate reception timestamp t. r .

[0072] Step S4.2: The ship's computer receives the UAV ranging timestamp data t relayed from the radio base station. sThe system collects real-time altitude data H from the UAV laser altimeter and preprocesses the data to eliminate significant errors and noise, thereby improving the accuracy of the data.

[0073] Step S5: The shipboard computer calculates the precise distance between the UAV and each radio base station based on the Time-of-Flight (TOF) method. Step S5 includes:

[0074] Step S5.1: Calculate the round-trip flight time Δt of the radio signals from the UAV to each base station based on the timestamps of radio signal transmission and reception.

[0075] Step S5.2: Calculate the precise distance between the UAV and each radio base station in real time using the Time-of-Flight (TOF) method, as shown in the following formula:

[0076]

[0077] Among them, D i Let represent the distance from the drone to the i-th base station, and c represent the speed of radio signal propagation, which is the speed of light (3 × 10⁻⁶). 8 m / s, The timestamp indicating the time of the drone's radio signal transmission. This represents the timestamp when the i-th base station receives the radio signal.

[0078] Step S5.3: After real-time verification and filtering of the distance data, output it to the next calculation stage.

[0079] Step S6: The ship's computer receives and processes radio distance data, laser altimeter height data, and differential RTK positioning data in real time, and calculates the UAV's three-dimensional coordinates using linear equation elimination. Step S6 includes:

[0080] Step S6.1: Receive the signal reception timestamp recorded by the radio base station and the laser altimeter altitude data transmitted by the UAV. Perform preliminary preprocessing and error elimination on the data, and store it in a standardized format. The preprocessing and error elimination include removing obvious abnormal data and eliminating significant errors caused by signal interference or equipment malfunctions; using filtering algorithms such as median filtering, Kalman filtering, or moving average filtering to remove abnormal raw data and suppress noise, thereby improving data quality and stability; and storing the preprocessed data in a standard format.

[0081] Step S6.2: Construct a system of three-dimensional spatial nonlinear equations with reference to the base station location, as shown in the following formulas:

[0082]

[0083] Among them, (X) i ,Y i Zi ) represents the coordinates of the i-th base station.

[0084] Step S6.3: Eliminate higher-order terms of the equation using the elimination method, simplifying the equation to a linear form, as shown below:

[0085] AX = B

[0086] Where A represents the coefficient matrix composed of the coordinates of each base station, X represents the three-dimensional coordinate matrix of the UAV to be determined, and B represents the constant term matrix composed of ranging data.

[0087] Step S6.4: Solve the system of linear equations to obtain the real-time and accurate three-dimensional spatial coordinates of the UAV.

[0088] Step S7: Based on continuous UAV three-dimensional coordinate data, obtain the UAV's real-time horizontal velocity and flight direction through differential calculation. Step S7 includes:

[0089] Step S7.1: Record the continuous three-dimensional spatial coordinates of the UAV in real time.

[0090] Step S7.2: Perform differential calculation on the continuous three-dimensional coordinate data to obtain the UAV's velocity vector. The calculation formula is as follows:

[0091]

[0092] Among them, V x V y V z These represent the velocity components of the drone in the X, Y, and Z axes, respectively.

[0093] Step S7.3: Calculate the real-time horizontal velocity and flight direction of the UAV based on the velocity vector, using the following formula:

[0094]

[0095] Among them, V hor θ represents the horizontal speed of the drone, and θ represents the flight direction angle of the drone.

[0096] Step S8: The calculated position information and real-time speed and direction information are converted into latitude, longitude, and altitude positioning information and sent to the UAV navigation and control system in real time. Step S8 includes the ship's end integrating and encapsulating the position and speed information into latitude, longitude, and altitude positioning data, which is then transmitted to the UAV in real time via wireless equipment. The UAV navigation system receives this data in real time and uses it as a precise basis for its own navigation and flight control. The encapsulated positioning information includes the UAV's real-time latitude and longitude coordinates, altitude, speed, heading angle, and UTC timestamp, etc.

[0097] Furthermore, the following is a detailed description of an example of calculating UAV positioning using base station and radio technology, with reference to the accompanying drawings:

[0098] See Figure 2 This is a flowchart illustrating an example of how the present invention calculates the location of a drone using base station and radio technology. Figure 1 A detailed explanation of the algorithm principles in steps S4 and S5:

[0099] The radio base station receives radio ranging signals actively transmitted by the drone in real time and accurately records the timestamp data t of the received signals. r Meanwhile, the radio communication module on the drone records the timestamp t of the transmitted ranging signal. s The ship's computer receives real-time timestamp data transmitted from the radio base station, as well as altitude information H measured by the laser altimeter and transmitted back from the UAV. Based on the timestamps of radio signal transmission and reception, the round-trip flight time Δt from the UAV to each base station is calculated. Assume the speed of radio signal propagation is the speed of light, c = 3 × 10⁻⁶. 8 If m / s, then the distance D from the drone to the i-th base station is... i It can be represented as:

[0100]

[0101] Among them, D i Let be the distance from the drone to the i-th base station, and c be the speed of radio signal propagation, which is the speed of light (3 × 10⁻⁶). 8 m / s, t is the timestamp for the radio signals transmitted by the drone. ri Let be the timestamp of the i-th base station receiving the radio signal. After calculating the distance data between the UAV and all base stations, a system of equations for three-dimensional spatial positioning is constructed by combining the differential RTK real-time coordinates of the base stations. Specifically, let the spatial coordinates of the base stations be: Base Station A: (X1,Y1,Z1), Base Station B: (X2,Y2,Z2), Base Station C: (X3,Y3,Z3), Base Station D: (X4,Y4,Z4), and let (X,Y,Z) be the unknown coordinates of the UAV to be solved.

[0102] A system of nonlinear equations concerning the UAV's position is established using the Euclidean distance formula:

[0103]

[0104] To simplify the calculation, linear elimination is used to transform the above nonlinear equation system into a linear equation system. Taking base station 1 as the baseline, subtracting the equation of base station 1 from the equations of base stations 2, 3, and 4 respectively eliminates all quadratic terms. Taking base station 2 as an example:

[0105]

[0106] After expansion and simplification, the equation becomes:

[0107]

[0108] Similarly, two other linear equations for base station 3 and base station 4 can be obtained:

[0109]

[0110] The above system of equations can be written in matrix form:

[0111] AX = B

[0112] in:

[0113] The coefficient matrix A is:

[0114]

[0115] The coordinate matrix X of the UAV to be solved is:

[0116]

[0117] The constant matrix B is:

[0118]

[0119] The position coordinates (X, Y, Z) of the UAV can be obtained by solving the system of linear equations.

[0120] To facilitate a clearer understanding of the technical solution of this invention by those skilled in the art, the following will refer to... Figure 3 The flowchart shown describes in detail the data fusion processing and position calculation process of the shipboard computer in this embodiment of the invention.

[0121] like Figure 3 As shown, the method for fusing and calculating the position of data fed back by the shipborne UAV by the shipborne computer in this embodiment includes the following steps:

[0122] Step 310: Data collection from base stations and drones.

[0123] In this embodiment, the radio base station and the drone deployed on the ship provide real-time feedback of the transmission and reception timestamps of the radio ranging signals, as well as the altitude data obtained in real-time by the drone's laser altimeter. The ship's computer receives and records this data in real time, including: the timestamp data of the drone transmitting radio signals, the timestamp data of the base station receiving drone signals, and the altitude data fed back by the drone from the laser altimeter.

[0124] Step 320: Data error elimination and filtering preprocessing.

[0125] The shipboard computer preprocesses the acquired radio ranging data and laser altimeter data. Specific methods include: removing obvious abnormal data to eliminate significant errors caused by signal interference or equipment malfunctions; using filtering algorithms such as median filtering, Kalman filtering, or moving average filtering to remove abnormal raw data and suppress noise, thereby improving data quality and stability; and storing the preprocessed data in a standard format for subsequent position and velocity calculation steps.

[0126] Step 330: Establish a system of equations to solve for the UAV coordinates.

[0127] Step 330 is a supplementary explanation of step S6. Based on the preprocessed radio ranging data, laser altimeter height data, and real-time acquired base station location data, the shipboard computer establishes a three-dimensional spatial positioning equation set. Specifically, this process includes defining the unknown location coordinates of the UAV as (X, Y, Z), and using the coordinates (X, Y, Z) of multiple base stations deployed on the ship... i ,Y i Z i Based on this, we construct a system of Euclidean distance equations for the UAV's position:

[0128]

[0129] To facilitate rapid calculation of the UAV's position coordinates, a linear equation elimination method is adopted. Taking one base station as a reference point, the nonlinear equations corresponding to the other base stations are subtracted from the equations of the reference base station to eliminate higher-order terms, resulting in the following system of linear equations:

[0130] AX = B

[0131] Where A is a coefficient matrix composed of the coordinates of each base station, X is the three-dimensional coordinate matrix of the UAV to be determined, and B is a constant term matrix composed of ranging data. Finally, the real-time three-dimensional position coordinates (X, Y, Z) of the UAV are calculated through matrix operations.

[0132] Step 340: Perform differential calculation based on continuous 3D coordinate data. The ship's computer continuously records the UAV's 3D spatial coordinate data at consecutive time points and performs differential calculation on data from adjacent time points.

[0133] Step 350: Solve for the real-time horizontal velocity and flight direction of the UAV. Based on the displacement vector data of the UAV obtained by the above differential calculation, calculate the real-time horizontal velocity and flight direction of the UAV.

[0134] The formula for calculating the real-time velocity vector of a drone is:

[0135]

[0136] Where Δt is the time interval between two adjacent data samples, and ΔX, ΔY, and ΔZ represent the displacement differences of the UAV along the X-axis, Y-axis, and Z-axis within the time interval Δt, respectively. x V y V z These represent the velocity components of the drone along the X, Y, and Z axes, respectively. The magnitude of the drone's horizontal velocity is:

[0137]

[0138] The formula for calculating the flight heading angle (heading angle) θ of a UAV is:

[0139]

[0140] The above formula can be used to obtain accurate flight speed and heading angle information of the UAV in real time.

[0141] Step 360: UAV positioning data encapsulation and transmission. The ship-borne computer encapsulates and transmits the UAV's real-time three-dimensional coordinate data and horizontal velocity V obtained from the above calculations. hor And the flight direction angle θ, which is encapsulated according to the standard GPS data format.

[0142] The encapsulated positioning information includes the UAV's real-time latitude and longitude coordinates, altitude, speed, heading angle, and UTC timestamp. Subsequently, the ship's computer transmits this data to the UAV navigation and control system in real time via a radio communication module. The UAV navigation and control system receives this data in real time and uses it for navigation and precise flight control.

[0143] Example 2

[0144] The present invention also provides a high-precision positioning system for shipborne unmanned aerial vehicles (UAVs) in polar regions. The high-precision positioning system for shipborne UAVs in polar regions can be implemented by executing the process steps of the high-precision positioning method for shipborne UAVs in polar regions. That is, those skilled in the art can understand the high-precision positioning method for shipborne UAVs in polar regions as a preferred embodiment of the high-precision positioning system for shipborne UAVs in polar regions.

[0145] A high-precision positioning system for shipborne unmanned aerial vehicles in polar regions, provided by the present invention, includes:

[0146] Module M1: Deploys a radio base station at the ship's bow and determines the base station's location in real time.

[0147] Module M2: The UAV carries a wireless device and a laser altimeter sensor. It performs distance measurement by communicating wirelessly with the ship's radio base station in real time at a fixed frequency and records the timestamps of the communication signals. In Module M2, the UAV's wireless device is frequency-matched with the base station. The UAV actively sends radio ranging signals to the base station at a fixed frequency and receives feedback signals from the base station in real time. The wireless device then records the timestamps of signal transmission and reception in real time.

[0148] Module M3: The UAV uses a laser altimeter to measure its altitude relative to the ground in real time.

[0149] Module M4: The radio base station and shipboard computer receive and process radio ranging data and laser altimeter height data transmitted from the UAV in real time. Module M4 includes: Module M4.1: The radio base station receives radio signals transmitted by the UAV in real time and records the accurate reception timestamp t. r Module M4.2: The ship's computer receives UAV ranging timestamp data t relayed from the radio base station. s The data includes the altitude data H transmitted in real time by the UAV laser altimeter, and the data is preprocessed to eliminate significant errors and noise.

[0150] Module M5: The shipboard computer calculates the precise distance between the UAV and each radio base station based on the Time-of-Flight (TOF) method. Module M5 includes: Module M5.1: Calculates the round-trip flight time Δt of the radio signals from the UAV to each base station based on the timestamps of radio signal transmission and reception; Module M5.2: Calculates the precise distance between the UAV and each radio base station in real time based on the TOF method, using the following formula:

[0151]

[0152] Among them, D i Let represent the distance from the drone to the i-th base station, and c represent the speed of radio signal propagation, which is the speed of light (3 × 10⁻⁶). 8 m / s, The timestamp indicating the time of the drone's radio signal transmission. The timestamp module M5.3, which indicates that the i-th base station received the radio signal, performs real-time verification and filtering on the distance data and outputs it to the next calculation stage.

[0153] Module M6: The ship's computer receives and processes radio distance data, laser altimeter altitude data, and differential RTK positioning data in real time, and calculates the UAV's three-dimensional coordinates using linear equation elimination. Module M6 includes: Module M6.1: Receives the signal reception timestamp recorded by the radio base station and the laser altimeter altitude data transmitted by the UAV, performs preliminary preprocessing and error elimination on the data, and stores it in a standardized format. Module M6.2: Constructs a system of three-dimensional nonlinear equations with the base station location as a reference, as shown in the following formula:

[0154]

[0155] Among them, (X) i ,Y i Z i Module M6.3: Eliminates higher-order terms in the equation using elimination methods, simplifying the equation to a linear form, as follows: AX = B, where A represents the coefficient matrix composed of the coordinates of each base station, X represents the three-dimensional coordinate matrix of the UAV to be determined, and B represents the constant term matrix composed of ranging data. Module M6.4: Solves the linear equation system to obtain the real-time accurate three-dimensional spatial coordinates of the UAV. The preprocessing and error elimination include removing obvious abnormal data, eliminating significant errors caused by signal interference or equipment errors, using filtering algorithms such as median filtering, Kalman filtering, or moving average filtering to remove abnormal raw data, suppress noise, and store the preprocessed data in a standard format.

[0156] Module M7: Based on continuous UAV 3D coordinate data, it obtains the UAV's real-time horizontal velocity and flight direction through differential calculation. Module M7 includes: Module M7.1: Real-time recording of continuous UAV 3D spatial coordinates; Module M7.2: Performing differential calculation on the continuous 3D coordinate data to obtain the UAV's velocity vector. The calculation formula is as follows:

[0157]

[0158] Where Δt is the time interval between two consecutive data samplings, ΔX, ΔY, and ΔZ represent the displacement differences of the UAV along the X-axis, Y-axis, and Z-axis within the time interval Δt, respectively, and V x V y V z Module M7.3 represents the velocity components of the UAV in the X, Y, and Z axes respectively: It calculates the UAV's real-time horizontal velocity and flight direction based on the velocity vectors, using the following formulas:

[0159]

[0160] Among them, V hor θ represents the horizontal speed of the drone, and θ represents the flight direction angle of the drone.

[0161] Module M8: Converts the calculated position information and real-time speed and direction information into latitude, longitude, and altitude positioning information, and sends it to the UAV navigation and control system in real time. Module M8 includes a ship-side component that integrates and encapsulates the position and speed information into latitude, longitude, and altitude positioning data, which is then transmitted in real time to the UAV navigation system via wireless equipment. The UAV navigation system receives this data in real time and uses it as the basis for its own navigation and flight control. The encapsulated positioning information includes the UAV's real-time latitude and longitude coordinates, altitude, speed, heading angle, and UTC timestamp.

[0162] like Figure 4 As shown, the shipborne unmanned aerial vehicle (UAV) high-precision positioning system of this invention includes: a ship 410, a radio base station 420 deployed on the ship, a ship-mounted computer 430, and a UAV 440. The radio base station on the ship is used for real-time radio communication with the UAV, the ship-mounted computer is used for data processing and position calculation, and the UAV is equipped with a radio communication module and a laser altimeter sensor for measuring distance and altitude information.

[0163] Specifically, the ship, as the core platform of this system, carries key positioning facilities, including four long-range radio base stations in the 915MHz band. These radio base stations are deployed at four specific locations on the ship, such as the bow, stern, and both sides of the hull, to achieve better measurement geometry and thus improve the accuracy of ranging and positioning. In addition, the ship is also equipped with high-precision differential RTK equipment to determine the precise geographical coordinates of each radio base station in real time.

[0164] The radio base station is specifically used to receive radio signals from the drone in real time. These signals carry precise timestamp information. Upon receiving the radio signals from the drone, the base station immediately records the precise reception timestamp and forwards this ranging data to the ship's computer in real time for further data processing and analysis. In addition, the radio base station also acts as a data relay node, sending the positioning data calculated by the ship's computer to the drone in real time to achieve navigation control.

[0165] The shipboard computer serves as the data processing and analysis center for the entire positioning system, receiving and processing various types of data from radio base stations and drones in real time. This data includes radio signal transmission and reception timestamps, altitude information measured by laser altimeters, and precise base station coordinates obtained through differential RTK. The shipboard computer preprocesses the received data to eliminate abnormal data and noise, ensuring high accuracy and stability in subsequent positioning calculations.

[0166] In the specific processing, the ship's computer first calculates the precise distance between the UAV and each radio base station based on the Time-of-Flight (TOF) method, and constructs a preliminary set of nonlinear equations. Subsequently, by constructing a set of three-dimensional linear equations, and using the precise coordinates of each radio base station as a reference, the three-dimensional spatial coordinates of the UAV are accurately solved using the linear equation elimination method.

[0167] The drone is equipped with a radio communication module and a laser altimeter sensor that are compatible with the base station. The radio communication module periodically and actively sends ranging signals to the base station and receives feedback signals in real time, while recording detailed transmission and reception timestamps to provide basic data for subsequent distance calculations based on the Time-of-Flight (TOF) method. The laser altimeter sensor is mounted on the bottom of the drone, continuously emitting laser pulses towards the ground at a fixed frequency and receiving reflected signals in real time. By measuring the round-trip flight time of the laser pulses, it obtains accurate ground altitude data of the drone in real time.

[0168] The shipboard computer also uses continuously acquired 3D spatial position data of the UAV to obtain the UAV's horizontal speed and flight direction information in real time using a differential calculation method. Specifically, the shipboard computer records the UAV's 3D coordinate position data at consecutive time points in real time, and then calculates the velocity vector based on the difference between adjacent time coordinate data, thereby obtaining the horizontal flight speed and flight direction.

[0169] Finally, the ship's computer integrates and encapsulates the precisely calculated three-dimensional coordinate data, real-time horizontal velocity, and flight direction information into UAV positioning data, which is then transmitted to the UAV in real time via a radio base station. The UAV navigation and control system receives this data in real time to achieve precise navigation and flight control, thereby ensuring flight stability and positioning accuracy in the complex dynamic environment of a ship.

[0170] In summary, this embodiment provides a high-precision and high-reliability shipborne UAV positioning system by integrating radio ranging, laser altimeter height measurement, and differential RTK technology, which can effectively meet the high-precision navigation requirements of shipborne UAVs in complex environments.

[0171] Those skilled in the art will understand that, besides implementing the system and its various devices, modules, and units provided by this invention in the form of purely computer-readable program code, the same functions can be achieved entirely through logical programming of the method steps, making the system and its various devices, modules, and units of this invention function in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers. Therefore, the system and its various devices, modules, and units provided by this invention can be considered as a hardware component, and the devices, modules, and units included therein for implementing various functions can also be considered as structures within the hardware component; alternatively, the devices, modules, and units for implementing various functions can be considered as both software modules implementing the method and structures within the hardware component.

[0172] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A high-precision positioning method for shipborne unmanned aerial vehicles (UAVs) in polar regions, characterized in that, include: Step S1: Deploy a radio base station at the ship's end and determine the base station's location in real time; Step S2: The UAV is equipped with wireless equipment and a laser altimeter sensor. It conducts distance measurement by communicating wirelessly with the ship's radio base station in real time via a fixed frequency and records the timestamp of the communication signal. Step S3: The UAV measures its altitude relative to the ground in real time using a laser altimeter; Step S4: The radio base station and shipboard computer receive and process the radio ranging data and laser altimeter height data transmitted back from the UAV in real time. Step S5: The shipboard computer calculates the precise distance between the UAV and each radio base station based on the time-of-flight method; Step S6: The shipboard computer receives and processes radio distance data, laser altimeter height data, and differential RTK positioning data in real time, and uses the linear equation elimination method to calculate the three-dimensional coordinates of the UAV. Step S7: Based on the continuous UAV three-dimensional coordinate data, obtain the UAV's real-time horizontal speed and flight direction through differential calculation; Step S8: Convert the calculated position information and real-time speed and direction information into latitude, longitude and altitude positioning information, and send it to the UAV navigation and control system in real time.

2. The high-precision positioning method for shipborne unmanned aerial vehicles in polar regions according to claim 1, characterized in that, In step S2, the UAV is equipped with a wireless device that matches the frequency of the base station. The UAV actively sends radio ranging signals to the base station at a fixed frequency and receives feedback signals from the base station in real time. Then, the wireless device records the signal transmission and reception timestamps in real time.

3. The high-precision positioning method for shipborne unmanned aerial vehicles in polar regions according to claim 1, characterized in that, Step S4 includes: Step S4.1: The radio base station receives the radio signals transmitted by the UAV in real time and records the accurate reception timestamp t. r ; Step S4.2: The ship's computer receives the UAV ranging timestamp data t relayed from the radio base station. s The data includes the altitude data H transmitted in real time by the UAV laser altimeter, and the data is preprocessed to eliminate significant errors and noise.

4. The high-precision positioning method for shipborne unmanned aerial vehicles in polar regions according to claim 1, characterized in that, Step S5 includes: Step S5.1: Calculate the round-trip flight time Δt of the radio signals from the UAV to each base station based on the timestamps of radio signal transmission and reception; Step S5.2: Calculate the precise distance between the UAV and each radio base station in real time using the Time-of-Flight (TOF) method, as shown in the following formula: Among them, D i Let represent the distance from the drone to the i-th base station, and c represent the speed of radio signal propagation, which is the speed of light (3 × 10⁻⁶). 8 m / s, The timestamp indicating the time of the drone's radio signal transmission. This represents the timestamp when the i-th base station receives the radio signal; Step S5.3: After real-time verification and filtering of the distance data, output it to the next calculation stage.

5. The high-precision positioning method for shipborne unmanned aerial vehicles in polar regions according to claim 1, characterized in that, Step S6 includes: Step S6.1: Receive the signal reception timestamp recorded by the radio base station and the laser altimeter height data transmitted by the UAV, perform preliminary preprocessing and error elimination on the data, and store it in a standardized format; Step S6.2: Construct a system of three-dimensional spatial nonlinear equations with reference to the base station location, as shown in the following formulas: Among them, (X) i ,Y i Z i () represents the coordinates of the i-th base station; Step S6.3: Eliminate higher-order terms of the equation using the elimination method, simplifying the equation to a linear form, as shown below: AX = B Where A represents the coefficient matrix composed of the coordinates of each base station, X represents the three-dimensional coordinate matrix of the UAV to be determined, and B represents the constant term matrix composed of ranging data. Step S6.4: Solve the system of linear equations to obtain the real-time and accurate three-dimensional spatial coordinates of the UAV.

6. The high-precision positioning method for shipborne unmanned aerial vehicles in polar regions according to claim 5, characterized in that, The preprocessing and error elimination include removing obvious abnormal data and eliminating significant errors caused by signal interference or equipment errors. The system employs filtering algorithms such as median filtering, Kalman filtering, or moving average filtering to remove abnormal raw data, suppress noise, and store the preprocessed data in a standard format.

7. The high-precision positioning method for shipborne unmanned aerial vehicles in polar regions according to claim 1, characterized in that, Step S7 includes: Step S7.1: Record the continuous three-dimensional spatial coordinates of the UAV in real time; Step S7.2: Perform differential calculations on the continuous three-dimensional coordinate data to obtain the UAV's velocity vector. The calculation formula is as follows: Where Δt is the time interval between two consecutive data samplings, ΔX, ΔY, and ΔZ represent the displacement differences of the UAV along the X-axis, Y-axis, and Z-axis within the time interval Δt, respectively, and V x V y V z These represent the velocity components of the UAV in the X, Y, and Z axes, respectively. Step S7.3: Calculate the real-time horizontal velocity and flight direction of the UAV based on the velocity vector, using the following formula: Among them, V hor θ represents the horizontal speed of the drone, and θ represents the flight direction angle of the drone.

8. The high-precision positioning method for shipborne unmanned aerial vehicles in polar regions according to claim 1, characterized in that, Step S8 includes the ship end integrating and encapsulating the position and speed information into latitude, longitude and altitude positioning data, which is then transmitted to the UAV in real time via wireless equipment; the UAV navigation system receives this data in real time and uses it as the basis for its own navigation and flight control. The encapsulated positioning information includes the UAV's real-time latitude and longitude coordinates, altitude, speed, heading angle, and UTC timestamp.

9. A high-precision positioning system for shipborne unmanned aerial vehicles (UAVs) in polar regions, characterized in that, include: Module M1: Deploys a radio base station at the ship's bow and determines the base station's location in real time; Module M2: The UAV is equipped with wireless equipment and a laser altimeter sensor. It conducts distance measurement through real-time wireless communication with the ship's radio base station at a fixed frequency and records the timestamp of the communication signal. Module M3: The UAV uses a laser altimeter to measure its altitude relative to the ground in real time; Module M4: The radio base station and shipboard computer receive and process radio ranging data and laser altimeter height data transmitted back from the UAV in real time; Module M5: The shipboard computer calculates the precise distance between the UAV and each radio base station based on the time-of-flight method; Module M6: The shipboard computer receives and processes radio distance data, laser altimeter height data, and differential RTK positioning data in real time, and uses the linear equation elimination method to calculate the UAV's three-dimensional coordinates. Module M7: Based on continuous UAV 3D coordinate data, it obtains the UAV's real-time horizontal speed and flight direction through differential calculation; Module M8: Converts the calculated position information and real-time speed and direction information into latitude, longitude, and altitude positioning information, and sends it to the UAV navigation and control system in real time.

10. The high-precision positioning system for shipborne unmanned aerial vehicles in polar regions according to claim 9, characterized in that, In module M2, the UAV is equipped with radio equipment that matches the frequency of the base station. The UAV actively sends radio ranging signals to the base station at a fixed frequency and receives feedback signals from the base station in real time. Then, the radio equipment records the signal transmission and reception timestamps in real time.

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