Unmanned rotorcraft autonomous take-off, landing and guiding system based on UWB and method thereof

Abstract

The invention provides a UWB-based unmanned rotorcraft autonomous take-off and landing and guidance system and method, and relates to the technical field of unmanned rotorcraft autonomous flight. The system comprises an unmanned aerial vehicle and a ground service platform which are both provided with 3D electronic compasses to establish an east-north-sky coordinate system; the unmanned aerial vehicle carries a UWB transceiver, the ground service platform integrates UWB receiving and transmitting nodes and three PDOA detectors, sensing-communication integrated distance measurement and angle measurement are realized through UWB, and spatial spherical coordinates are constructed to complete relative positioning; the ground service platform plans a take-off and landing trajectory containing key points, the unmanned aerial vehicle flies autonomously along the trajectory based on a flight control system of the unmanned aerial vehicle, and soft landing and accurate take-off are achieved in combination with an altimeter. An asymmetric design is adopted, complex signal processing and positioning services are deployed on the ground, and the unmanned aerial vehicle can be adapted only by being externally connected with a UWB transceiver. According to the invention, universal autonomous take-off, landing and guidance of the unmanned aerial vehicle in the midway service station of the air route are realized, multi-vehicle collaborative operation is supported, the anti-interference capability is strong, and the reliability is high.

Description

Technical Field

[0001] This invention relates to the field of autonomous flight technology for unmanned aerial vehicles (UAVs), specifically to an autonomous take-off, landing, and guidance system and method for a UWB-based rotary-wing UAV. Background Technology

[0002] As a core carrier of the low-altitude economy, unmanned aerial vehicles (UAVs), especially electric rotor UAVs, have been widely used in urban and suburban logistics, inspection and monitoring, and emergency rescue scenarios due to their advantages such as high mobility, no runway required, low noise, high cost-effectiveness, environmental friendliness, and ease of maintenance. With the explosive growth in the number of UAVs, manual remote control can no longer meet the needs of large-scale, long-range operations, and the autonomous take-off, landing, and flight capabilities of UAVs have become a key technological bottleneck.

[0003] Existing autonomous take-off and landing technologies for drones have several limitations: First, they lack versatility, with most drones only able to take off and land at the manufacturer's dedicated airports, unable to adapt to general service stations along the route; second, they are limited in function, only supporting return take-off and landing after battery depletion, lacking the ability to autonomously land, recharge, and take off again mid-flight for continuous operation; third, they have high system complexity, with some solutions integrating complex positioning and signal processing modules into the drone, leading to increased cost, weight, and energy consumption, affecting endurance; fourth, they have weak multi-drone coordination capabilities, with existing technologies requiring large amounts of communication, making it difficult for a single service station to accommodate multiple drones simultaneously, resulting in low operational efficiency; fifth, they rely on external communication, with some solutions requiring complex satellite navigation or terrestrial communication networks for positioning assistance, exhibiting weak anti-interference capabilities and insufficient reliability in complex environments.

[0004] The future development of the low-altitude economy requires the deployment of general-purpose service stations along flight routes, similar to electric vehicle charging stations, to enable drones to resupply and take off / land mid-flight. Therefore, there is an urgent need for a universal, low-cost, low-energy-consumption, interference-resistant, and multi-drone collaborative autonomous takeoff, landing, and guidance technology to overcome the limitations of existing technologies. Summary of the Invention

[0005] This invention provides a UWB-based autonomous take-off and landing and guidance system and method for rotary-wing unmanned aerial vehicles (UAVs), aiming to solve the technical problems of poor versatility, high cost, high energy consumption, and weak multi-aircraft coordination in existing UAV autonomous take-off and landing systems, and to achieve accurate autonomous take-off and landing and efficient guidance of UAVs at general service stations.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0007] In a first aspect, the present invention provides an autonomous take-off and landing and guidance system for a rotary-wing unmanned aerial vehicle based on UWB, including the unmanned aerial vehicle and a ground service platform;

[0008] Both the drone and the ground service platform are equipped with 3D electronic compasses to establish a unified northeast-northeast coordinate system.

[0009] The UAV is equipped with a UWB transceiver, and the ground service platform is configured with a UWB transceiver node and at least two PDOA detectors.

[0010] The UAV and the ground service platform achieve integrated perception and communication interaction through UWB, complete relative ranging and angle measurement, and construct spatial spherical coordinates to determine the real-time position of the UAV relative to the ground service platform;

[0011] The ground service platform plans take-off and landing trajectories based on the real-time location. The UAV autonomously completes take-off and landing actions along the take-off and landing trajectory through its own flight control system. The UAV and the ground service platform adopt an asymmetric architecture design, with complex signal processing and positioning calculation functions deployed on the ground service platform.

[0012] As a further improvement to the technical solution of the present invention, the asymmetric architecture design is specifically as follows:

[0013] The UWB transceiver of the UAV consists only of a UWB transceiver module and an MCU circuit, and achieves positioning and communication functions by communicating with the UAV's original flight control system.

[0014] The ground service platform also integrates a signal processing unit for performing UWB signal analysis, DS-TWR ranging algorithm calculation, PDOA angle measurement algorithm calculation, and coordinate transformation processing.

[0015] As a further improvement to the technical solution of the present invention, the number of PDOA detectors is three, and the three PDOA detectors are arranged in a triangle at the middle of the edge of the ground service platform and at two opposite vertices; each PDOA detector is equipped with four antennas, and the four antennas are distributed in a square on the same PCB board to form two pairs of angle measurement antennas, which are used to measure the heading angle and pitch angle of the UAV respectively.

[0016] As a further improvement to the technical solution of the present invention, the integrated perception-communication interaction between the UAV and the ground service platform via UWB includes:

[0017] After the UAV sends a service request frame and the ground service platform responds, the two interact through Poll, Resp, Final and Ack frames. The ground service platform calculates the distance between the UAV and the ground service platform based on the DS-TWR algorithm, and measures the pitch and heading angles of the UAV through the PDOA detector.

[0018] As a further improvement to the technical solution of the present invention, the take-off and landing trajectory planned by the ground service platform is described by multiple key points. The flight control system of the UAV autonomously controls the UAV to fly from one key point to the next key point according to the control target performance function, thus completing trajectory construction and flight.

[0019] As a further improvement to the technical solution of the present invention, the ground service platform uses a rotation transformation algorithm to convert the angle parameters in the XYZ coordinate system measured by the PDOA detector into the heading angle and pitch angle in the northeast-sky coordinate system, and then sends them to the UAV.

[0020] As a further improvement to the technical solution of the present invention, the flight control system of the UAV is equipped with an angle control objective function. By adjusting the flight attitude of the UAV, the UAV enters the ground service platform from a preset direction while maintaining a safe distance from other UAVs. The angle control objective function satisfies that the heading angle of the UAV's entry direction is less than... .

[0021] A second aspect of the present invention provides a method for autonomous take-off, landing, and guidance of a UWB-based rotary-wing unmanned aerial vehicle (UAV), applied to the aforementioned UWB-based autonomous take-off, landing, and guidance system for a rotary-wing UAV, the method comprising:

[0022] S1: The UAV and the ground service platform establish a northeast-north-southeast coordinate system respectively through their respective configured 3D electronic compasses;

[0023] S2: The UAV flies to the preset range of the target ground service platform via satellite navigation and sends a UWB service request to the ground service platform;

[0024] S3: After responding to the request, the ground service platform interacts with the UWB frame, calculates the distance between them using the DS-TWR algorithm, measures the pitch and heading angles of the UAV using the PDOA detector, and constructs spatial spherical coordinates to determine the real-time position of the UAV.

[0025] S4: The ground service platform plans a take-off and landing trajectory containing multiple key points based on the real-time location and sends it to the drone;

[0026] S5: The UAV autonomously flies along the take-off and landing trajectory based on its own flight control system, and achieves soft landing or precise take-off by combining with the altimeter.

[0027] As a further improvement to the technical solution of the present invention, in step S3, the ground service platform takes the average value of the angle parameters measured by the three PDOA detectors to obtain the final pitch angle and heading angle of the UAV; and calculates the altitude of the UAV relative to the ground service platform based on the distance and pitch angle.

[0028] As a further improvement to the technical solution of the present invention, the spacing between the four antennas of the PDOA detector is half of the wavelength corresponding to the center frequency of UWB. The incident angle of the UAV is calculated by combining the phase difference of the received UWB signal with the wavelength parameter.

[0029] The technical solution of the present invention has the following advantages over the prior art:

[0030] This invention achieves precise real-time positioning of the UAV relative to the ground service platform by constructing a unified northeast-southeast coordinate system between the UAV and the ground service platform, and by integrating UWB perception and communication in a unified interactive design. Combined with angle measurement from the PDOA detector and spatial spherical coordinate positioning, it achieves precise real-time positioning of the UAV relative to the ground service platform with almost no reliance on external communication, strong anti-interference capability, and high reliability. Its asymmetric architecture deploys complex signal processing and positioning calculation functions on the ground service platform, requiring only an external lightweight UWB transceiver for the UAV to adapt, significantly reducing the hardware cost, weight, and energy consumption of the UAV, with minimal impact on the original flight control system and strong versatility. At the same time, the ground service platform plans take-off and landing trajectories based on real-time location, combined with the UAV's autonomous trajectory tracking capability. This not only supports the UAV's autonomous take-off, landing, and guidance at general service stations along the flight path, meeting the needs of long-range operations, but also ensures safe spacing between multiple UAVs through reasonable planning, improving the efficiency of multi-UAV collaborative operations at the same service station. This effectively solves the technical pain points of existing UAV autonomous take-off and landing, such as poor versatility, high cost, and weak multi-UAV collaboration. Attached Figure Description

[0031] 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:

[0032] Figure 1 This is a diagram of the UWB-based perception-communication system architecture of the UAV and ground service platform shown in the embodiments of this application;

[0033] Figure 2 This is a schematic diagram of the telemetry and control system structure of the UAV shown in the embodiment of this application;

[0034] Figure 3 This is a schematic diagram of the antenna distribution of the PDOA detector shown in the embodiments of this application;

[0035] Figure 4 This is a schematic diagram of DS-TWR ranging communication and PDOA measurement between the UAV and the ground service platform, as shown in the embodiments of this application;

[0036] Figure 5 This is a UWB interaction flowchart between the UAV and the ground service platform as shown in the embodiments of this application;

[0037] Figure 6This is a schematic diagram of the UWB system structure of the ground service platform shown in the embodiments of this application;

[0038] Figure 7 This is a schematic diagram of the take-off and landing trajectory and process of the UAV as shown in the embodiments of this application. Detailed Implementation

[0039] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0040] The present invention will be further described in detail below with reference to the accompanying drawings.

[0041] Reference Figure 1 In a first aspect, the present invention provides an autonomous take-off and landing and guidance system for a rotary-wing unmanned aerial vehicle based on UWB, including the unmanned aerial vehicle and a ground service platform;

[0042] Both the drone and the ground service platform are equipped with 3D electronic compasses to establish a unified northeast-northeast coordinate system.

[0043] The UAV is equipped with a UWB transceiver, and the ground service platform is configured with a UWB transceiver node and at least two PDOA detectors.

[0044] The UAV and the ground service platform achieve integrated perception and communication interaction through UWB, complete relative ranging and angle measurement, and construct spatial spherical coordinates to determine the real-time position of the UAV relative to the ground service platform;

[0045] The ground service platform plans take-off and landing trajectories based on the real-time location. The UAV autonomously completes take-off and landing actions along the take-off and landing trajectory through its own flight control system. The UAV and the ground service platform adopt an asymmetric architecture design, with complex signal processing and positioning calculation functions deployed on the ground service platform.

[0046] It should be noted that the UAV and the ground service platform establish a unified northeast-northeast coordinate system through their respective 3D electronic compasses, providing a consistent benchmark for relative positioning. The UWB transceiver on the UAV and the UWB transceiver node on the ground service platform achieve integrated perception-communication interaction. At least two PDOA detectors on the ground service platform simultaneously measure the UAV's pitch and heading angles. Combining the distance parameters obtained from UWB ranging with the angle parameters obtained from PDOA angle measurement, a spatial spherical coordinate system is constructed to accurately determine the UAV's real-time position relative to the ground service platform. Based on this real-time position, the ground service platform plans takeoff and landing trajectories, and the UAV autonomously completes takeoff and landing maneuvers along these trajectories using its own flight control system. An asymmetric architecture design is adopted, deploying complex computational functions such as UWB signal analysis, ranging and angle measurement algorithms, and coordinate transformation on the ground service platform, while the UAV retains only basic UWB communication and data forwarding functions.

[0047] This invention combines a unified coordinate system with an integrated UWB sensing-communication design, achieving precise relative positioning between the UAV and the ground service platform with minimal reliance on external communication. The inherent strong anti-interference capabilities of UWB technology ensure reliable system operation even in complex environments. The asymmetric architecture significantly simplifies UAV hardware configuration, requiring only an external lightweight UWB transceiver for adaptation without modifying the core structure of the original flight control system. This reduces UAV hardware costs, weight, and energy consumption, improves endurance, and enhances system versatility, adapting to different types of rotary-wing UAVs. The ground service platform's trajectory planning and UAV autonomous tracking mode support autonomous takeoff, landing, and guidance at general service stations along the flight path, meeting the needs of long-range operations. Furthermore, reasonable trajectory planning ensures safe spacing between multiple UAVs, improving the efficiency of multi-UAV collaborative operations at the same service station and effectively addressing the pain points of poor versatility, high cost, and weak multi-UAV collaboration in existing technologies.

[0048] In some embodiments, the asymmetric architecture design specifically refers to:

[0049] The UWB transceiver of the UAV consists only of a UWB transceiver module and an MCU circuit, and achieves positioning and communication functions by communicating with the UAV's original flight control system.

[0050] The ground service platform also integrates a signal processing unit for performing UWB signal analysis, DS-TWR ranging algorithm calculation, PDOA angle measurement algorithm calculation, and coordinate transformation processing.

[0051] It should be noted that the asymmetric architecture design clearly defines the functional boundaries between the UAV and the ground service platform. The UAV's UWB transceiver, consisting of a UWB transceiver module and an MCU circuit, is only responsible for UWB signal transmission and reception and data forwarding with the ground service platform. It transmits positioning information and trajectory parameters from the ground to the UAV's existing flight control system through communication, without participating in complex signal processing and calculations. The ground service platform integrates a dedicated signal processing unit that specifically performs UWB signal analysis, DS-TWR ranging algorithm calculations, PDOA angle measurement algorithm calculations, and coordinate transformation processing. After completing the positioning calculation, it sends the results to the UAV.

[0052] The UAV only requires a lightweight UWB transceiver for functional adaptation, with minimal impact on the existing flight control system. This reduces the difficulty and cost of UAV modification, while also reducing hardware weight and power consumption, extending flight range. The ground service platform centrally handles complex computing tasks, resulting in higher computational efficiency and facilitating subsequent algorithm optimization and functional upgrades, leading to lower system maintenance costs. This design achieves a rational allocation of functions, balancing the UAV's lightweight requirements with the system's computational accuracy, thus enhancing the overall system's practicality and scalability.

[0053] In some embodiments, the number of PDOA detectors is three, and the three PDOA detectors are arranged in a triangle at the middle of the edge of the ground service platform and at two opposite vertices; each PDOA detector is equipped with four antennas, and the four antennas are distributed in a square on the same PCB board to form two pairs of angle measurement antennas, which are used to measure the heading angle and pitch angle of the UAV respectively.

[0054] It should be noted that the three PDOA detectors are arranged in a triangle around the edge of the ground service platform and at two opposite vertices, forming a redundant measurement layout. Each PDOA detector's PCB board is equipped with four antennas arranged in a square pattern, forming two pairs of angle measurement antennas. One pair of antennas measures the UAV's heading angle, and the other pair measures the pitch angle. By receiving the UWB signal transmitted by the UAV through multiple antennas, and utilizing the correlation between the signal phase difference and the incident angle, the measurement data for the heading and pitch angles are calculated respectively.

[0055] The triangular arrangement of three PDOA detectors provides redundant backup for angle measurements. Multiple sets of data verification enhance measurement reliability, and the angle parameters achieve higher accuracy after cross-verification by multiple detectors. The square-distributed antenna array and angle measurement antenna pairs accurately capture heading and pitch angle signals respectively, ensuring the targeted and accurate nature of angle measurements. This layout and antenna configuration provide reliable angle data support for the construction of spatial spherical coordinates, further improving the accuracy of UAV relative positioning and laying the foundation for subsequent trajectory planning and autonomous takeoff and landing.

[0056] In some embodiments, the integrated perception-communication interaction between the UAV and the ground service platform via UWB includes:

[0057] After the UAV sends a service request frame and the ground service platform responds, the two interact through Poll, Resp, Final and Ack frames. The ground service platform calculates the distance between the UAV and the ground service platform based on the DS-TWR algorithm, and measures the pitch and heading angles of the UAV through the PDOA detector.

[0058] It should be noted that after the UAV flies to the preset range of the ground service platform, it first sends a UWB service request frame (Req frame). The ground service platform responds by sending a Reply frame to confirm service capability. Subsequently, the two exchange Poll, Resp, and Final frames sequentially, recording the corresponding timestamps during each frame's transmission and reception. Based on these timestamps, the ground service platform calculates the distance parameters between itself and the UAV using the DS-TWR algorithm. Simultaneously, the PDOA detector measures the UAV's pitch and heading angles while receiving each UWB signal frame. After integrating the distance and angle parameters, the ground service platform feeds back the positioning results and related parameters to the UAV via an Ack frame.

[0059] The UWB frame interaction process enables simultaneous ranging and communication, eliminating the need for separate ranging and communication channels and reducing data transmission volume and interaction latency. The collaborative application of the DS-TWR ranging algorithm and the PDOA angle measurement algorithm ensures the synchronization and accuracy of distance and angle parameter measurements. The strong anti-interference capability of UWB technology allows the interaction process to continue stably even in complex electromagnetic environments. The entire interaction process is logically clear and compact, ensuring real-time positioning data while reducing system communication overhead, thus improving the reliability and efficiency of interaction between the UAV and the ground service platform.

[0060] In some embodiments, the take-off and landing trajectory planned by the ground service platform is described by multiple key points. The UAV's flight control system autonomously controls the UAV to fly from one key point to the next key point according to the control target performance function, thus completing trajectory construction and flight.

[0061] It should be noted that the ground service platform plans takeoff and landing trajectories and extracts multiple key points based on the UAV's real-time location, its own positioning, and the flight status of surrounding UAVs. These key points include core parameters such as coordinates, flight speed limits, and attitude constraints. After the ground service platform sends these key point parameters to the UAV, the UAV's flight control system calls the control target performance function. Based on its own attitude measurement data and position feedback information, the UAV autonomously constructs a continuous flight trajectory from its current position to each key point, controlling the UAV to smoothly fly from one key point to the next, completing the entire takeoff and landing process.

[0062] The ground service platform only needs to plan key points to describe the complete takeoff and landing trajectory, significantly simplifying the complexity of trajectory planning, reducing the amount of data transmission between the ground and the UAV, and lowering communication bandwidth consumption. The UAV's autonomous construction of continuous trajectories improves adaptability and adjustment flexibility, enabling it to handle minor positional deviations during flight. This design allows the same ground service station to simultaneously plan independent key point trajectories for multiple UAVs, avoiding flight conflicts and significantly improving the efficiency and safety of multi-UAV coordinated takeoff and landing.

[0063] In some embodiments, the ground service platform uses a rotation transformation algorithm to convert the angle parameters in the XYZ coordinate system measured by the PDOA detector into the heading angle and pitch angle in the northeast-sky coordinate system, and then sends them to the UAV.

[0064] It should be noted that the angle parameters measured by the PDOA detector are initially based on its own XYZ coordinate system, while the positioning reference of the UAV and the ground service platform is the Northeast-East-South coordinate system. There is a difference in the rotation angles along the z-axis between the two. The signal processing unit of the ground service platform calls a rotation transformation algorithm to convert the pitch and heading angles in the XYZ coordinate system measured by the PDOA detector, combined with the rotation angle parameters measured by the 3D electronic compass, into the corresponding angle parameters in the Northeast-East-South coordinate system. These converted angle parameters are then sent to the UAV for positioning calculations and trajectory planning.

[0065] This invention unifies angle parameters across different coordinate systems through a rotation transformation algorithm, ensuring consistent positioning references between the UAV and the ground service platform. This avoids positioning errors caused by coordinate system differences and improves the accuracy of relative positioning. The transformation process is automatically completed by the ground service platform's signal processing unit without manual intervention, boasts high computational efficiency, and does not affect the real-time performance of positioning and trajectory planning, providing reliable angle data support for the UAV to accurately track its takeoff and landing trajectories.

[0066] In some embodiments, the UAV's flight control system is configured with an angle control objective function. By adjusting the UAV's flight attitude, the UAV enters the ground service platform from a preset direction while maintaining a safe distance from other UAVs. The angle control objective function satisfies that the heading angle of the UAV's entry direction is less than... .

[0067] It should be noted that the UAV's flight control system has a built-in angle control objective function, which uses the direction in which the UAV enters the ground service platform as a constraint. Based on real-time heading and pitch angle data fed back from the ground service platform, the flight control system dynamically adjusts the UAV's flight attitude to ensure that the UAV enters from the ground service platform in a preset direction (e.g., DE to C), and strictly controls the heading angle of the entry direction to be less than... By minimizing the value of the angle control objective function, the drone can be precisely aligned with the take-off and landing area of ​​the ground service platform, while maintaining a safe distance from other drones taking off and landing.

[0068] The design of the angle control objective function provides a clear constraint on the approach direction of the UAV, effectively avoiding flight conflicts when multiple UAVs take off and land on the same ground service platform, and ensuring the safety of multi-UAV collaborative operations. The heading angle is less than... The constraints ensure that the drones can enter the take-off and landing area smoothly and accurately, reducing the difficulty of attitude adjustment during soft landing and minimizing equipment wear and tear. This design enables the ground service platform to coordinate multiple drones to take off and land simultaneously, improving the operational efficiency and space utilization of the service station.

[0069] A second aspect of the present invention provides a method for autonomous take-off, landing, and guidance of a UWB-based rotary-wing unmanned aerial vehicle (UAV), applied to the aforementioned UWB-based autonomous take-off, landing, and guidance system for a rotary-wing UAV, the method comprising:

[0070] S1: The UAV and the ground service platform establish a northeast-north-southeast coordinate system respectively through their respective configured 3D electronic compasses;

[0071] S2: The UAV flies to the preset range of the target ground service platform via satellite navigation and sends a UWB service request to the ground service platform;

[0072] S3: After responding to the request, the ground service platform interacts with the UWB frame, calculates the distance between them using the DS-TWR algorithm, measures the pitch and heading angles of the UAV using the PDOA detector, and constructs spatial spherical coordinates to determine the real-time position of the UAV.

[0073] S4: The ground service platform plans a take-off and landing trajectory containing multiple key points based on the real-time location and sends it to the drone;

[0074] S5: The UAV autonomously flies along the take-off and landing trajectory based on its own flight control system, and achieves soft landing or precise take-off by combining with the altimeter.

[0075] This invention comprehensively covers the entire process of autonomous takeoff and landing and guidance for unmanned aerial vehicles (UAVs). From coordinate system establishment and navigation positioning to trajectory tracking and autonomous takeoff and landing, each step is logically coherent and tightly integrated, highly compatible with the corresponding system architecture, ensuring the feasibility of the technical solution. Through the coordinated application of satellite navigation and UWB positioning, a smooth transition from long-range coarse positioning to short-range fine positioning is achieved, meeting the positioning requirements of different flight phases. This method supports UAVs in completing autonomous takeoff, landing, and resupply at general service stations along the flight path, breaking through the limitation of existing technologies that only support takeoff and landing at dedicated factory airports. This provides technical support for long-range UAV operations and improves the flexibility and continuity of low-altitude economic operations.

[0076] In some embodiments, in step S3, the ground service platform takes the average of the angle parameters measured by the three PDOA detectors to obtain the final pitch angle and heading angle of the UAV; and calculates the altitude of the UAV relative to the ground service platform based on the distance and pitch angle.

[0077] It should be noted that in step S3, the signal processing unit of the ground service platform collects the pitch and heading angle data measured by the three PDOA detectors respectively, and optimizes the angle parameters by averaging to obtain the final pitch and heading angles, reducing the measurement error of a single detector. Based on the distance r between the UAV and the ground service platform calculated by the DS-TWR algorithm, combined with the optimized pitch angle θ, the altitude h of the UAV relative to the ground service platform is calculated using trigonometric functions to achieve an approximate altitude measurement; when the UAV is within 5-10 meters of the ground service platform, the system switches to the altimeter on the UAV for precise altitude measurement.

[0078] The average angle parameters of the three PDOA detectors are processed to effectively offset the random measurement errors of a single detector, improving the stability and accuracy of angle measurements. The method of calculating altitude using distance and pitch angle allows the UAV to achieve satisfactory altitude measurements even without expensive altimeters such as high-precision millimeter-wave radar, reducing equipment costs. It is also compatible with inexpensive ultrasonic altimeters and high-precision millimeter-wave radar, improving the system's hardware adaptability. The tiered approach to altitude measurement balances the convenience of long-distance measurements with the accuracy of short-distance measurements, providing reliable altitude data support for UAV soft landings and precise takeoffs.

[0079] In some embodiments, the spacing between the four antennas of the PDOA detector is half the wavelength corresponding to the UWB center frequency. The incident angle of the UAV is calculated by combining the phase difference of the received UWB signal with the wavelength parameter.

[0080] It should be noted that the four antennas of the PDOA detector are arranged in a square pattern, with the spacing between adjacent antennas set to half the wavelength corresponding to the UWB center frequency. This spacing design conforms to the propagation characteristics of UWB signals and maximizes the antenna's sensitivity to the phase difference of the received signal. After the UWB signal transmitted by the UAV is received by the antenna pairs of the PDOA detector, the phase difference between the received signals of the two antennas is measured. Combined with the wavelength parameters of UWB electromagnetic waves, the relationship between the phase difference and the incident angle is used to calculate the incident angle of the UAV relative to the PDOA detector, providing basic data for determining the heading and pitch angles.

[0081] The matching design between the antenna spacing and the UWB center frequency wavelength enables the antenna pair to accurately capture phase difference changes in the UWB signal, improving the sensitivity and resolution of the incident angle measurement. The incident angle calculation method based on phase difference is reliable in principle and simple to operate, enabling the rapid acquisition of high-precision angle data, providing high-quality raw data for subsequent angle optimization and coordinate positioning. This design ensures the accuracy of PDOA angle measurement, further improving the overall accuracy of spatial spherical coordinate positioning, and providing key technical support for the precise tracking of UAV autonomous take-off and landing trajectories.

[0082] To provide a clearer understanding of the invention, the invention is further described below:

[0083] This invention provides an autonomous take-off, landing, and guidance system for rotary-wing unmanned aerial vehicles (UAVs) based on UWB. As the UAV approaches from a distance, its positioning accuracy increases, ultimately allowing it to precisely land on the UAV platform. The UAV platform determines a series of flight path points based on the distance to the UAV in the air, and the UAV is precisely guided to the platform via these points. The main invention features include:

[0084] 1. Both the ground service platform and the UAV are equipped with 3D electronic compasses, establishing a northeast-sky coordinate system for each. A UWB transceiver node is installed on the UAV, and in addition to one UWB transceiver node, three UWB-based PDOA (Phase Difference of Arrival) detectors are installed on the ground service platform. The ground service platform and the UAV communicate and measure distances through the transceiver nodes in an integrated sensing-communication manner. The three PDOA detectors on the ground service platform measure the angles (pitch angle θ and heading angle φ) of the UAV relative to the northeast-sky coordinate system of the ground service platform, thereby constructing a spatial spherical coordinate system based on the northeast-sky coordinate system of the ground service platform. This allows the drone to obtain its coordinates relative to the ground service platform. Through coordinate transformation between the ground service platform and the drone, the drone can take off and land according to the guidance trajectory of the ground service platform.

[0085] 2. The aerial UAV only uses DS-TWR (Double Side Two-way Ranging) to measure the distance between the UAV and the ground service platform. The drone does not communicate with the PDOA detector, reducing communication overhead; the ground service platform communicates with the three PDOA detectors. , , and , , The average value is used to determine the spatial spherical coordinate angle θ of the UAV and Ground service platform according to and Calculate the altitude of the drone relative to the ground service platform The plan guides the drones to descend onto the ground service platform, maintaining sufficient distance from other drones to ensure the safe and efficient take-off and landing of multiple drones.

[0086] 3. The ground service platform describes the take-off and landing trajectory by setting multiple key points for the UAV. The UAV is autonomously controlled by its own flight control system to fly from one key point to the next according to the control target performance function. When the UAV reaches directly above the UAV ground platform and needs to land, it soft-lands to the ground service platform according to the altimeter. When it needs to take off, it takes off above the ground platform according to the altimeter and then flies according to the key points of the trajectory.

[0087] 4. An asymmetric design is adopted, with the complex UWB signal processing and positioning services located on the ground service platform, while the UAV only needs to be equipped with a UWB transceiver. The UAV's UWB transceiver consists of a UWB transceiver module and an MCU circuit. It communicates with the UAV's existing flight control system to achieve communication and positioning with the ground service platform, making it simple and lightweight. The ground service station is equipped with a UWB transceiver and three PDOA detectors. The asymmetric design reduces the installation cost, weight, and energy consumption of the UAV.

[0088] To make the technical solution of the present invention clearer and easier to understand, the present invention will be described in detail below with reference to specific embodiments.

[0089] Example:

[0090] like Figure 1This is a perception-communication system structure consisting of an unmanned aerial vehicle (UAV) and a ground service platform. The UAV is equipped with an onboard UWB node A, and the ground service platform also has a similar UWB node B. Both nodes have half-duplex UWB communication capabilities. The ground service platform also has three PDOA detectors: PDOA detectors C, D, and E, arranged in a triangle and mounted at the middle of the platform's edge and at two opposite vertices. The PDOA detectors only have detection functions and do not transmit UWB signals or communicate. The UWB transceiver chips all use the DW1000. The asymmetrical design of the UAV and ground service platform simplifies the UAV's hardware structure and reduces costs; only the existing flight control system needs to be equipped with UWB transceivers (i.e., UWB nodes). The UWB transceiver consists of an M205 MCU circuit and an M206 UWB transceiver module. Figure 2 As shown.

[0091] like Figure 3 As shown, the PDOA detector has four antennas arranged in a square on the same PCB board, each connected to one of four DW1000 chips. The side length of the square is half the wavelength corresponding to the UWB center frequency (e.g., 33mm for a center frequency of 4492.8MHz). These four antennas can form two pairs of PDOA angle measurement antennas, G1-G4 and G2-G3, used to measure the angle between the UAV and the surrounding environment. Figure 1 The angle formed by the XOZ plane, i.e., the heading angle of the ground service platform relative to the UAV; G1-G2 and G4-G3 are used to measure the... Figure 1 The angle formed by the XOY plane is the pitch angle of the ground service platform relative to the UAV. The measurement principles for G1-G4, G2-G3, G1-G2, and G4-G3 are as follows: Figure 4 As shown.

[0092] Figure 2 This is the structure of the UAV telemetry and control system. M201's IMU uses the ICM-42688, containing a 3-axis gyroscope, a 3-axis accelerometer, and a 3-axis electronic compass. M202 is the satellite positioning system, using GPS or BDS. M204 is the altimeter, which can be an inexpensive ultrasonic altimeter or a more expensive millimeter-wave radar. M203 is the flight control system, which adjusts the UAV's altitude and attitude by controlling the propeller speed via electric drive based on the UAV's altitude and attitude measurements. M205 and M206 are the UAV's UWB transceivers, consisting of an MCU circuit and a UWB transceiver module. The MCU uses an STM32G474CB, and the UWB chip uses a DW1000, enabling relative positioning and communication with the ground service platform.

[0093] like Figure 4As shown, when UAV node A and ground UWB node B conduct DS-TWR ranging communication, the PDOA antenna also receives the UWB signal from UAV node A. The figure shows a schematic diagram of a pair of PDOA antennas at PDOA nodes C, D, and E receiving UWB signals. Figure 4 During flight, if a drone requires service from a ground service platform, it locates the nearest platform on an electronic map and navigates to its vicinity (within 50 meters) using satellite navigation (GPS or BeiDou). Then, it sends a UWB service request signal to the ground service platform via the UWB channel. Figure 5 (Req frame in the text).

[0094] like Figure 5 In Step 511, UAV node A sends a Req request service frame, which is received by ground service platform node B and the PDOA detector. If the ground service platform is willing to provide service, it sends a Reply frame in Step 522. In Step 512, after receiving the Reply frame, UAV node A sends a Poll frame based on the parameters provided by the ground service platform (specific parameters such as the address and location of the ground service platform), and records the sending time. Ground service platform node B and the PDOA detector receive the Poll frames in Steps 523 and 533, and record the Poll frame reception time. After a fixed period of time (TrespB), ground service platform node B sends a Resp frame in Step 524. UAV node A receives Resp frames, which contain the reception time of Poll frames and the transmission time of Resp frames. After a fixed time delay (TrespA), UAV node A sends a Final frame in Step 515. The Final frame contains the reception time of Resp frames and the transmission time of the Final frame. Ground service platform node B (Step 525) and PDOA detector (Step 535) both receive the Final frame and record the reception time of the frame. Ground service platform node B can calculate the distance r between node A and node B based on the transmission and reception times of these frames using the DS-TWR algorithm. It can also calculate the spatial spherical coordinate angles θ and φ of the UAV using the PDOA algorithm and inform UAV node A by sending an Ack frame.

[0095] The DS-TWR distance between ground service platform node B and UAV node A after exchanging Poll, Resp, Final, and Ack frames is:

[0096] (1)

[0097] In the formula, r is the distance between the drone and the ground service platform. The time of flight of UWB electromagnetic waves between the drone and the ground service platform; The speed of light in air is a constant. , , and The physical meaning of Figure 5 It has already been marked.

[0098] During DS-TWR ranging process Figure 4 The PDOA antenna pair receives Req frames, Poll frames, and Final frames sent by the UAV. Each time the PDOA antenna receives a UWB signal from the UAV, it can calculate the UAV's angle of incidence using an algorithm. (Reference) Figure 4 The relative angle measurement method based on PDOA utilizes the phase difference between electromagnetic waves received from the same signal source by two antenna pairs (such as G1-G4) spaced d apart. The phase difference between the electromagnetic waves received by antennas G1 and G4 is... Angle of incidence of the UWB signal source of the drone relative to the two antennas There is a corresponding relationship.

[0099] (2)

[0100] in This refers to the wavelength of the UWB electromagnetic wave. Similarly, based on the phase difference experienced by other antennas during each connection of the G2-G3, G1-G2, and G4-G3 antenna pairs, the incident angle of the UAV relative to other planes can be calculated.

[0101] (3)

[0102] (4)

[0103] (5)

[0104] The final incident angles at different azimuths are obtained by averaging the incident angles measured by the two sets of antennas:

[0105] (6)

[0106] (7)

[0107] Equations (6) and (7) represent the angles relative to the XYZ coordinate system measured by each PDOA detector. The common coordinate system of the UAV and the ground service platform is the Northeast-East-South coordinate system, which generally has a rotation angle along the z-axis with the XYZ coordinate system on the horizontally placed ground service platform. The ground service platform needs to undergo rotation transformation to send the heading and pitch angles of the ground service platform relative to the UAV to the UAV. Therefore, Figure 1 The northeast-sky coordinate system measured by the three PDOA detectors C, D, and E is as follows:

[0108] (8)

[0109] (9)

[0110] (10)

[0111] in, The rotation angle between the XYZ coordinate system and the Northeast-Eastern-Sky coordinate system. and These are the heading and pitch angles relative to the UAV in the XYZ coordinate system of node C of the ground service platform. and These are the heading and pitch angles of the ground service platform C node relative to the UAV in the northeast sky coordinate system, respectively. and These are the heading and pitch angles relative to the UAV in the XYZ coordinate system of node D of the ground service platform. and These are the heading and pitch angles of the ground service platform node D relative to the UAV in the northeast sky coordinate system, respectively. and These are the heading and pitch angles relative to the UAV in the XYZ coordinate system of the ground service platform node E. and These are the heading and pitch angles of the ground service platform E node relative to the UAV in the northeast sky coordinate system. Figure 6 This is the UWB system architecture of the ground service platform. M601 is the MCU circuit, composed of a 100-pin STM32G474VB and its peripheral circuitry; M602 is the UWB transceiver module, composed of a DW1000 chip and its peripheral circuitry; M603 is the electronic compass, composed of an HMC5883L and its peripheral circuitry; M604 consists of three PDOA modules, respectively... Figure 1 The three modules, C, D, and E, each consist of a 48-pin MCU (STM32G474CB), four DW1000s, and so on. Figure 3 The system consists of four antennas, G1, G2, G3, and G4, positioned at various locations. The MCU of M601 is connected to M603 via an I2C interface, to M602 via an SPI interface, and to M604 via an SPI interface.

[0112] refer to Figure 7Taking landing as an example (the takeoff sequence is reversed), when the drone is at point P1 (the key point), it sends a request for service to the ground service platform. After the ground service platform agrees to provide the service, both parties complete the positioning process. The ground service platform then sends the drone the next trajectory point P2, and the drone autonomously arrives near point P2. When the drone is relatively high above the ground, without expensive altitude measurement equipment such as millimeter-wave radar, positioning can only be achieved through satellite positioning (such as GPS and BDS) and barometers, resulting in significant errors. When near the ground service platform (e.g., around 50 meters), approximate altitude measurement can also be performed using UWB. Figure 7 As shown, when the drone is located at point P2, if the distance from point B to point P2 is known, then the following approximate formula applies:

[0113] (11)

[0114] (12)

[0115] (13)

[0116] Figure 1 The distance between points B and C in the equation is very small relative to the side length of the ground service platform. The length of BC is about 0.2m, while the lengths of CD, CE and DE are generally greater than 2m. Therefore, the approximate value of the UAV in the northeast-north-sky coordinate system of the ground service platform given by equation (11) has sufficient accuracy. When the distance between the UAV and point B is within 5 to 10 meters, the h value can be obtained by using an ultrasonic altimeter, which can replace the h value obtained by equations (11) and (12).

[0117] During the drone's descent onto the ground service platform, in addition to controlling its altitude (h), it also needs to control its angle relative to the platform. The real-time heading and pitch angles at points C, D, and E, measured by the ground service platform, are as follows: and , and , and The objective function for controlling these components during the drone's descent is...

[0118] (12)

[0119] The control objective for the drone's landing is to make Minimum requirement: the drone must enter the ground service platform from the midway point between points D and E, and the drone must enter the ground service platform from the DE direction towards C. Figure 7In the middle, enter the center of the ground service platform from the right, thus ensuring a safe distance between drones during takeoff and landing between different ground service platforms. From the perspective of drone control, this requires... <90°.

[0120] Based on trajectory points P3 and P4 provided by the ground service platform, the drone autonomously controls itself to move from point P2 to point P3 and then to point P4, i.e., above the drone's ground platform. The drone uses its own ultrasonic altimeter to obtain its altitude h relative to the ground service platform and then autonomously soft-lands on it. The takeoff and landing processes are reversed.

[0121] The technical solutions provided by the embodiments disclosed in this invention have the following beneficial effects:

[0122] High versatility: This invention breaks through the limitation of existing drones that can only take off and land at the original factory's dedicated airport. Through UWB perception-communication integration technology, it realizes the autonomous take-off, landing and guidance of drones at general service stations, adapts to different types of rotary-wing drones, and provides technical support for the route-based operation of low-altitude economy.

[0123] The asymmetric design offers significant advantages: by deploying complex signal processing and positioning calculation functions on a ground service platform, the drone only needs to be connected to a lightweight UWB transceiver to achieve compatibility, without the need to modify the original core architecture of the flight control system. This greatly reduces the hardware cost, weight, and energy consumption of the drone, and extends its flight range.

[0124] Precise positioning and strong anti-interference capability: The system adopts a combination of DS-TWR ranging algorithm and PDOA angle measurement algorithm to construct spatial spherical coordinates to realize the relative positioning of UAV, with high measurement accuracy; UWB technology itself has the characteristics of anti-multipath interference and strong penetration capability, and the system hardly relies on external communication, so it can still maintain stable and reliable operation in complex environments.

[0125] Supports multi-drone collaborative operation: By designing the objective function for key point trajectory planning and angle control, the amount of communication between the ground and the drone is reduced. The same ground service station can accommodate multiple drones to take off and land in an orderly manner at the same time, ensuring the safety and efficiency of multi-drone operation.

[0126] It boasts comprehensive functions and high practicality: it supports autonomous landing, charging, and takeoff of drones mid-flight, meeting the needs of long-range operations; the soft landing and precise takeoff control mechanism improves the stability of the takeoff and landing process and reduces equipment wear and tear.

[0127] In summary, this invention addresses many pain points of existing autonomous take-off and landing technologies for unmanned aerial vehicles (UAVs) through technological innovations such as UWB perception-communication integration, asymmetric architecture, multi-algorithm fusion positioning, and key point trajectory planning. It has significant technological advancements and practical application value.

[0128] The technical solutions provided by the embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the embodiments of the present invention. The descriptions of the embodiments above are only for helping to understand the principles of the embodiments of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the embodiments of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A UWB-based autonomous take-off, landing, and guidance system for rotary-wing unmanned aerial vehicles, characterized in that, Including drones and ground service platforms; Both the drone and the ground service platform are equipped with 3D electronic compasses to establish a unified northeast-northeast coordinate system. The UAV is equipped with a UWB transceiver, and the ground service platform is configured with a UWB transceiver node and at least two PDOA detectors. The UAV and the ground service platform achieve integrated perception and communication interaction through UWB, complete relative ranging and angle measurement, and construct spatial spherical coordinates to determine the real-time position of the UAV relative to the ground service platform; The ground service platform plans take-off and landing trajectories based on the real-time location. The UAV autonomously completes take-off and landing actions along the take-off and landing trajectory through its own flight control system. The UAV and the ground service platform adopt an asymmetric architecture design, with complex signal processing and positioning calculation functions deployed on the ground service platform.

2. The UWB-based autonomous take-off and landing and guidance system for rotary-wing unmanned aerial vehicles according to claim 1, characterized in that: The asymmetric architecture design is specifically as follows: The UWB transceiver of the UAV consists only of a UWB transceiver module and an MCU circuit, and achieves positioning and communication functions by communicating with the original flight control system of the UAV. The ground service platform also integrates a signal processing unit for performing UWB signal analysis, DS-TWR ranging algorithm calculation, PDOA angle measurement algorithm calculation, and coordinate transformation processing.

3. The UWB-based autonomous take-off and landing and guidance system for rotary-wing unmanned aerial vehicles according to claim 1, characterized in that: The number of PDOA detectors is three, and the three PDOA detectors are arranged in a triangle at the middle of the edge of the ground service platform and at two opposite vertices. Each PDOA detector is equipped with four antennas, which are distributed in a square on the same PCB board to form two pairs of angle measurement antennas, which are used to measure the heading angle and pitch angle of the UAV.

4. The UWB-based autonomous take-off and landing and guidance system for rotary-wing unmanned aerial vehicles according to claim 1, characterized in that: The integrated perception-communication interaction between the UAV and the ground service platform via UWB includes: After the UAV sends a service request frame and the ground service platform responds, the two interact through Poll, Resp, Final and Ack frames. The ground service platform calculates the distance between the UAV and the ground service platform based on the DS-TWR algorithm, and measures the pitch and heading angles of the UAV through the PDOA detector.

5. The UWB-based autonomous take-off and landing and guidance system for rotary-wing unmanned aerial vehicles according to claim 1, characterized in that: The take-off and landing trajectory planned by the ground service platform is described by multiple key points. The UAV's flight control system autonomously controls the UAV to fly from one key point to the next key point according to the control target performance function, thus completing trajectory construction and flight.

6. The UWB-based autonomous take-off and landing and guidance system for rotary-wing unmanned aerial vehicles according to claim 1, characterized in that: The ground service platform uses a rotation transformation algorithm to convert the angle parameters in the XYZ coordinate system measured by the PDOA detector into the heading and pitch angles in the northeast-sky coordinate system, and then sends them to the UAV.

7. The UWB-based autonomous take-off and landing and guidance system for rotary-wing unmanned aerial vehicles according to claim 1, characterized in that: The UAV's flight control system is equipped with an angle control objective function. By adjusting the UAV's flight attitude, the UAV enters the ground service platform from a preset direction while maintaining a safe distance from other UAVs. The angle control objective function satisfies that the heading angle of the UAV's entry direction is less than... .

8. A method for autonomous take-off, landing, and guidance of a UWB-based rotary-wing unmanned aerial vehicle, characterized in that, Applied to the system according to any one of claims 1-7, the method comprises: S1: The UAV and the ground service platform establish a northeast-north-southeast coordinate system respectively through their respective configured 3D electronic compasses; S2: The UAV flies to the preset range of the target ground service platform via satellite navigation and sends a UWB service request to the ground service platform; S3: After responding to the request, the ground service platform interacts with the UWB frame, calculates the distance between them through the DS-TWR algorithm, measures the pitch and heading angles of the UAV through the PDOA detector, and constructs spatial spherical coordinates to determine the real-time position of the UAV. S4: The ground service platform plans a take-off and landing trajectory containing multiple key points based on the real-time location and sends it to the drone; S5: The UAV autonomously flies along the take-off and landing trajectory based on its own flight control system, and achieves soft landing or precise take-off by combining with the altimeter.

9. The wastewater potential energy transport and wind / solar energy treatment system based on high elevation difference in mountainous terrain as described in claim 8, characterized in that: In step S3, the ground service platform takes the average of the angle parameters measured by the three PDOA detectors to obtain the final pitch angle and heading angle of the UAV; and calculates the altitude of the UAV relative to the ground service platform based on the distance and pitch angle.

10. The wastewater potential energy transport and wind / solar energy treatment system based on high elevation difference in mountainous terrain as described in claim 8, characterized in that: The spacing between the four antennas of the PDOA detector is half the wavelength corresponding to the center frequency of UWB. The incident angle of the UAV is calculated by combining the phase difference of the received UWB signal with the wavelength parameter.

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