Guiding method and system for autonomous landing of unmanned aerial vehicle

Abstract

The invention relates to a guiding method and system for autonomous landing of an unmanned aerial vehicle, and the unmanned aerial vehicle comprises n ultra-wideband tag modules. Receiving the receiving timestamps of the data frames sent by the n ultra-wideband label modules received by the m ultra-wideband base station modules, the sending timestamps of the data frames sent by the m ultra-wideband base station modules in the current superframe and the inertial sensor data of the take-off and landing platform from the take-off and landing platform, wherein m and n are greater than or equal to 1; calculating a ranging value according to the receiving timestamp, the sending timestamp, the timestamps of the data frames sent by the n ultra-wideband tag modules and the timestamps of the data frames received by the n ultra-wideband tag modules from the m ultra-wideband base station modules; calculating attitude information according to the distance measurement value, inertial sensor data of the take-off and landing platform and inertial sensor data of the unmanned aerial vehicle; and controlling the unmanned aerial vehicle to complete landing according to the attitude information. According to the scheme, autonomous landing of the unmanned aerial vehicle can be completed without depending on satellite navigation and a visual sensor.

Description

Technical Field

[0001] The present application relates to the field of drone technology, and in particular to a method and system for guiding autonomous landing of a drone. Background Art

[0002] Unmanned aerial vehicles (UAVs), as unmanned aerial vehicles, have been widely used in various fields in recent years. Due to their ease of use, maneuverability, and high level of intelligence, UAVs have become an indispensable tool in both military and civilian fields. In the military, UAVs are widely used for tasks such as aerial reconnaissance, electronic jamming, target location and tracking, and border patrol. These tasks require UAVs to be highly maneuverable and intelligent, capable of performing tasks in complex environments. Furthermore, UAVs have demonstrated tremendous potential in the civilian sector, with widespread use in aerial photography, disaster monitoring, pesticide spraying, and other fields, significantly improving work efficiency and operational accuracy.

[0003] Among the many types of drones, rotary-wing drones (UAVs) are attracting increasing attention due to their unique performance advantages. They not only possess the ability to take off and land vertically, but can also hover and fly flexibly in any direction. These advantages make them particularly effective in tasks requiring precise control and operation, such as precision agriculture, urban planning, and building inspection. With technological advancements and increasing application demands, the application prospects of rotary-wing UAVs in various fields are becoming increasingly broad.

[0004] However, with the rapid development of drone technology, the safe and reliable recovery of drones after their mission has become a critical issue. Drone recovery not only affects reusability but also overall operating costs and safety. Currently, common drone recovery methods can be categorized into four types: parachute recovery, arrested recovery, manual recovery, and autonomous landing recovery.

[0005] Parachute recovery is a traditional recovery method. It involves equipping a drone with a parachute, which deploys according to a pre-programmed sequence after the mission, allowing the drone to land safely. However, this method is susceptible to external factors, particularly strong winds, making it difficult to achieve a precise, targeted landing. Therefore, while parachute recovery is simple and easy to implement, its application scenarios are limited.

[0006] Arresting recovery relies on external devices. Under ground control, the drone lowers its altitude and speed, ultimately impacting an elastic arresting net. Once inside, its speed rapidly decreases to zero, allowing it to land. While this method is effective for drone recovery, it requires specialized arresting gear, limiting its application to specialized scenarios.

[0007] Manual recovery is a more flexible method. By switching the drone's automatic control mode to remote control, the ground pilot manually controls the drone's landing. While this method relies on the pilot's control skills, it remains highly adaptable in complex environments. However, it requires a high level of pilot skill and cannot achieve fully autonomous recovery.

[0008] Autonomous landing and recovery represents the next evolutionary step in drone recovery technology. Leveraging the drone's sensors and autonomous controllers, the system can achieve autonomous landing without human intervention. As modern missions increasingly demand higher performance from drones, autonomous landing has become a crucial feature in drone systems. Autonomous landing not only significantly improves recovery efficiency but also reduces reliance on ground operators, while also helping to enhance drone endurance and mission completion rates.

[0009] Currently, autonomous landing technology primarily relies on satellite navigation and positioning and visual perception. While significant progress has been made in this area, technical limitations still exist in certain situations. For example, autonomous recovery of drones becomes challenging in scenarios where visual perception cannot be relied upon, such as at night or in inclement weather, or when satellite navigation signals are interfered with, blocked, or unavailable. Furthermore, autonomous landing becomes significantly more difficult when a drone needs to land on a moving platform, such as a moving vehicle. Summary of the Invention

[0010] In order to solve the problem that drones have difficulty in achieving autonomous landing in scenarios where visual perception cannot be relied upon or satellite navigation signals are poor, the present application provides a guidance solution for autonomous landing of drones that can achieve autonomous landing of drones without relying on satellite navigation and visual sensors.

[0011] According to a first aspect of the present application, a method for guiding autonomous landing of a drone is provided, which is applied to the drone, characterized in that the drone includes n ultra-wideband tag modules, and the method includes:

[0012] In a preset time slot of the current superframe, receiving from the take-off and landing platform the reception timestamp of the data frames sent by the n ultra-wideband tag modules received by the m ultra-wideband base station modules, the transmission timestamp of the data frames sent by the m ultra-wideband base station modules in the current superframe, and the inertial sensor data of the take-off and landing platform, where m and n are both greater than or equal to 1;

[0013] Calculate the distance value between the UAV and the take-off and landing platform according to the receiving timestamp, the sending timestamp, the timestamps of the n ultra-wideband tag modules sending the data frames, and the timestamps of the n ultra-wideband tag modules receiving the data frames from the m ultra-wideband base station modules;

[0014] Calculating attitude information of the UAV based on the ranging value, the inertial sensor data of the take-off and landing platform, and the inertial sensor data of the UAV; and

[0015] The UAV is controlled to complete landing according to the posture information of the UAV.

[0016] According to a second aspect of the present application, a method for guiding autonomous landing of a drone is provided, which is applied to a take-off and landing platform, wherein the take-off and landing platform includes m ultra-wideband base station modules, and the method includes:

[0017] In a preset time slot of the current superframe, the receiving timestamps of the data frames sent by the n ultra-wideband tag modules of the drone, the sending timestamps of the data frames sent by the m ultra-wideband base station modules, and the inertial sensor data of the take-off and landing platform are sent, wherein m and n are both greater than or equal to 1, so that the drone calculates the ranging value between the drone and the take-off and landing platform according to the receiving timestamp, the sending timestamp, the timestamp of the data frames sent by the n ultra-wideband tag modules, and the timestamp of the data frames received by the n ultra-wideband tag modules from the m ultra-wideband base station modules, and calculates the attitude information of the drone according to the ranging value, the inertial sensor data of the take-off and landing platform, and the inertial sensor data of the drone;

[0018] receiving ranging values ​​from the n ultra-wideband tag modules; and

[0019] The power of sending the data frame is adjusted according to the ranging value.

[0020] According to a third aspect of the present application, a guidance system for autonomous landing of a UAV is provided, characterized in that it includes:

[0021] A drone for performing the method according to the first aspect; and

[0022] A take-off and landing platform is used to execute the method described in the second aspect.

[0023] According to a fourth aspect of the present application, an electronic device is provided, comprising a memory storing one or more programs and a processor electrically coupled to the memory and configured to execute the one or more programs to perform any method or step or combination thereof in the present application.

[0024] According to a fifth aspect of the present application, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, it causes the execution of any method or step or a combination thereof in the present application.

[0025] According to the method and system for guiding autonomous landing of unmanned aerial vehicles provided in this application, the drone and the take-off and landing platform transmit and receive data according to a predetermined superframe format. The drone determines the distance measurement value between itself and the take-off and landing platform based on the transmission and reception timestamps of the drone and the take-off and landing platform. Then, the ranging value, the inertial sensor data of the take-off and landing platform, and the inertial sensor data of the drone are calculated to obtain the drone's attitude information, thereby controlling the drone to complete autonomous landing. The solution of this application completes the confirmation of attitude information and the control of autonomous landing based on the data exchange between the drone and the take-off and landing platform, and does not rely on satellite navigation and visual sensors to achieve autonomous landing of the drone. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without exceeding the scope of protection required by this application.

[0027] Figure 1 This is a schematic diagram of the composition of a guidance system for autonomous landing of a drone according to an embodiment of the present application.

[0028] Figure 2 This is a schematic diagram of components on a take-off and landing platform according to an embodiment of the present application.

[0029] Figure 3 Schematic diagram of components on a drone according to one embodiment of the present application.

[0030] Figure 4 yes Figure 1 Schematic diagram of the system showing how to achieve autonomous landing of a drone.

[0031] Figure 5 This is a schematic diagram of the superframe structure for ultra-wideband ranging communication between a drone and a take-off and landing platform according to an embodiment of the present application.

[0032] Figure 6 This is a working status diagram of the take-off and landing platform according to an embodiment of the present application.

[0033] Figure 7 yes Figure 1 The system shown is a flow chart of how the UAV can be autonomously landed.

[0034] Figure 8 2 is a schematic diagram of a drone performing ultra-wideband ranging according to an embodiment of the present application.

[0035] Figure 9 Schematic diagram of a UAV performing flight posture calculation according to one embodiment of the present application.

[0036] Figure 10 This is a flowchart of a method for guiding autonomous landing of a drone performed by a drone according to an embodiment of the present application.

[0037] Figure 11 This is a flowchart of a method for guiding autonomous landing of a drone performed by a take-off and landing platform according to an embodiment of the present application.

[0038] Figure 12 This is a structural diagram of an electronic device provided by this application. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of this application.

[0040] Figure 1 FIG. 1 is a schematic diagram of a guidance system for autonomous landing of a UAV according to an embodiment of the present application. Figure 1 As shown, the system includes a take-off and landing platform and a UAV, wherein the take-off and landing platform can be a vehicle-mounted take-off and landing platform. The take-off and landing platform on the ground moves at a certain speed v c Sports (v c can be 0), the drone in the air is controlled autonomously at a speed v d The drone approaches the take-off and landing platform and finally lands on it. During the entire process, neither the drone nor the take-off and landing platform has satellite positioning information or other visual-related indication information.

[0041] Figure 2 This is a schematic diagram of components on a take-off and landing platform according to an embodiment of the present application. Figure 3 FIG is a schematic diagram of components on a drone according to an embodiment of the present application. Figure 2 and Figure 3As shown in the figure, an ultra-wideband module and an inertial sensor are installed on the take-off and landing platform. The ultra-wideband module on the take-off and landing platform is called an "ultra-wideband base station module", and the ultra-wideband module of the drone is called an "ultra-wideband tag module". The inertial sensor can be a 3G3A inertial sensor.

[0042] exist Figure 2 In the illustrated embodiment, the landing platform includes four ultra-wideband base station modules—UWB A1, UWB A2, UWB A3, and UWB A4—located at the four corners of the platform, forming a rectangular arrangement with a length of L and a width of W. A 3G3A inertial sensor is placed at the center of the landing platform, with the sensor's coordinate axis origin located at the landing platform's origin. In one specific embodiment, the landing platform's origin can be the drone's landing target.

[0043] The layout of the take-off and landing platforms is not limited to Figure 2 In the given embodiment, for example, the number of ultra-wideband base station modules may not be four, but may be one, two, or any number. If the number is greater than two, the multiple ultra-wideband base station modules are preferably positioned so that the area of ​​the pattern formed by the modules is as large as possible. In an optional embodiment, the take-off and landing platform may also include an odometer to measure the platform's speed relative to the ground.

[0044] exist Figure 3 In the embodiment shown, two ultra-wideband tag modules UWB T1 and UWB T2 are placed on the two wings of the drone, and the distance between the center of the module and the origin of the drone's body coordinate axis is d. When the number of ultra-wideband tag modules is greater than one, they can be set on different wings of the drone. Similarly, a 3G3A inertial sensor is placed at the center of the drone, and the origin of the inertial sensor coordinate system coincides with the center of the drone, and the line connecting its coordinate axis and the two ultra-wideband tag modules forms a certain angle θ. The arrangement of the drone is not limited to Figure 3 In the given embodiment, in an optional embodiment, the drone can be equipped with only one ultra-wideband tag module, and the aforementioned functions can also be achieved. It only requires that there is a certain distance between the installation position of the module and the coordinate origin of the inertial device IMU (Inertial Measurement Unit), and the larger the distance, the better.

[0045] It is understood by those skilled in the art that the placement of the UWB base station module and the UWB tag module in the take-off and landing platform and the UAV is not limited to Figure 2 and Figure 3 The method shown here only needs the UWB base station module and the UWB tag module to be able to send and receive data frames normally.

[0046] The implementation process of the present application scheme is roughly as follows: multiple ultra-wideband modules on the take-off and landing platform and the drone jointly form a local measurement and transmission collaborative network, define the data superframe format of the ultra-wideband air interface between the take-off and landing platform and the drone, and the ultra-wideband base station module of the take-off and landing platform and the ultra-wideband tag module of the drone send data frames within the time slot specified by the superframe format. The drone determines the ranging value between itself and the take-off and landing platform based on its own and the take-off and landing platform's transmission and reception timestamps. Then, the ranging value, the take-off and landing platform's inertial sensor data, and the drone's inertial sensor data are settled to obtain the drone's attitude information, thereby controlling the drone to complete autonomous landing.

[0047] The functional module block diagram of the UAV autonomous landing process is as follows Figure 4 The take-off and landing platform and the UAV can measure the distance through the data frame interaction between the modules. At the same time, the sensor data on the take-off and landing platform can be transmitted to the UAV, and the computing unit on the UAV is responsible for solving the pose in the local coordinate system.

[0048] like Figure 4 As shown, ultra-wideband communication is performed between the take-off and landing platform and the UAV. During the process of sending and receiving data, the UAV obtains the relevant ultra-wideband transmission and reception timestamps between the take-off and landing platform and the UAV, performs ranging solution based on the transmission and reception timestamps, and determines the ranging value between the take-off and landing platform. Then, based on the ranging value, the inertial sensor data measured by the UAV itself (such as the three-dimensional linear acceleration and three-dimensional angular velocity of the UAV), and the inertial sensor data measured by the take-off and landing platform (such as the platform motion speed, three-dimensional linear acceleration and three-dimensional angular velocity), the flight posture settlement is performed to determine the posture of the landing point of the take-off and landing platform in the UAV body coordinate system. Finally, the UAV's flight controller issues flight control commands to control the lift and torque in the UAV coordinate system, and the UAV's electrode system executes the sub-control commands to achieve autonomous landing.

[0049] The data superframe format of the ultra-wideband air interface for ultra-wideband communication between the take-off and landing platform and the UAV is as follows: Figure 5 As shown. Figure 5 In , each superframe contains multiple time slots. Each UWB module sends data frames in the corresponding time slot according to its module ID and receives data frames from other modules in other time slots. A superframe includes a time slots corresponding to m UWB base station modules and n UWB tag modules, where a = m + n. Figure 2 and Figure 3 In the setting of the ultra-wideband base station module and the ultra-wideband tag module shown, the superframe includes 6 time slots corresponding to 4 ultra-wideband base station modules and 2 ultra-wideband tag modules respectively, the first four time slots correspond to 4 ultra-wideband base station modules, and the last two time slots correspond to 2 ultra-wideband tag modules.

[0050] On the take-off and landing platform, among the multiple ultra-wideband modules, one can be used as the main base station module, responsible for receiving data information from the inertial sensor, and the remaining modules can be used as ordinary base station modules. After completing time synchronization, the main base station module and other base station modules send ranging data frames in their respective allocated time slots. Among them, the data frame sent by the main base station module contains the reception timestamp of the data frame sent by the drone module in the previous superframe, the transmission timestamp of the current superframe, the on-board inertial sensor data, and optional on-board odometer data information. The data frames sent by other base station modules can only contain the reception timestamp of the data frame sent by the drone module in the previous superframe and the transmission timestamp of the current superframe.

[0051] The drone is equipped with at least one ultra-wideband module. This module first synchronizes time with each base station by listening to data frames on the air interface. Once synchronized, the module transmits data frames within its assigned time slot. In an optional embodiment, the data frames may include the distance measurement between the drone module and the base station module on the vehicle-mounted take-off and landing platform, calculated based on the transmit and receive timestamps.

[0052] In a specific embodiment, according to Figure 1 The system shown in FIG1 includes an ultra-wideband base station module (Anchor1, Anchor2, Anchor3 and Anchor4, referred to as "A1, A2, A3 and A4") and two ultra-wideband tag modules (TAG1 and TAG2, referred to as "T1 and T2"). The positions of the four ultra-wideband base station modules in the coordinate system of the vehicle-mounted take-off and landing platform are recorded as Where m = 1, 2, 3, 4. The positions of the two UWB modules on the drone in the drone body coordinate system are Where n=1,2. The above six ultra-wideband modules are respectively Figure 5 The data frame is sent in the corresponding time slot of the superframe shown in FIG. 1 , wherein the fields in the data frame sent by A1 as the primary base station can be:

[0053] (1) Synchronization header (SYNC);

[0054] (2) Synchronization header end indication (SFD, used to detect the end of the synchronization header, the end time of this field is the corresponding timestamp);

[0055] (3) The sending timestamp of the current frame (tmark);

[0056] (4) The receiving timestamp (RMARK1) of the data frame sent by T1 received in the previous frame, that is, the receiving timestamp of the data frame sent by the ultra-wideband tag module T1 received by the master base station;

[0057] (5) The receiving timestamp (RMARK2) of the data frame sent by T2 received in the previous frame, that is, the receiving timestamp of the data frame sent by the ultra-wideband tag module T2 received by the master base station;

[0058] (6) Inertial sensor data at the start of the current superframe, including the three-dimensional angular velocity output by the gyroscope and the three-dimensional acceleration output by the accelerometer (IMU);

[0059] (7) If the take-off and landing platform has reliable odometer information, the odometer data field (ODOM) can also be included. Odometer information can be used to improve the calculation accuracy during the pose calculation process.

[0060] The fields in the data frames sent by the four ultra-wideband base station modules A2, A3 and A4 do not include IMU and ODOM. The others are the same as A1, including SYNC, SFD, RMARK1 and RMARK2. Among them, RMARK1 is the reception timestamp of the data frame sent by the ultra-wideband tag module T1 received by the ultra-wideband base station module A2, A3 or A4, and RMARK2 is the reception timestamp of the data frame sent by the ultra-wideband tag module T2 received by the ultra-wideband base station module A2, A3 or A4.

[0061] The two ultra-wideband tag modules T1 and T2 send ultra-wideband ranging signals, and the fields in the sent data frames may only include SYNC and SFD.

[0062] In an optional embodiment, in addition to SYNC and SFD, the data frame sent by the ultra-wideband tag module may also contain a RANGE field to transmit the average distance between the tag module and the four base station modules that has been recently calculated. Since the distance between the drone and the base station can be shortened from several kilometers to several meters during landing, the dynamic range can reach 60dB (about 1000 times). In order to ensure the accuracy of the ultra-wideband module ranging, in addition to dynamic gain adjustment at the receiving end, the transmission gain can be adjusted according to the current distance at the transmitting end, such as Figure 6 As shown in the figure, the ranging value is calculated on the drone's computing platform, so it needs to be included in the data frame sent by the drone. To reduce air interface transmission volume, it is possible to transmit only the average of the ranging values ​​from multiple base stations to the drone.

[0063] exist Figure 6In the illustrated embodiment, during the takeoff and landing of a drone, the state of the takeoff and landing guidance section on the landing platform switches as follows: after starting the mission, the ultra-wideband base station transmits a ranging frame at maximum power while listening to the transmission time slot allocated to the drone. Upon detecting the ranging frame transmitted by the drone, the ultra-wideband base station places the received timestamp in the next superframe and transmits it, while adjusting the transmission power based on the value of the RANGE field in the received ranging frame. If the ultra-wideband base station does not detect the ranging frame transmitted by the drone within a period of time, it returns to the state of transmitting at maximum power so that the drone can complete the ranging and communication link connection with the base station as quickly as possible. By adjusting the transmission power based on the ranging value, the landing platform can improve the accuracy of ranging.

[0064] After receiving data frames from the takeoff and landing platform, the UWB module on the drone extracts the receive and transmit timestamps and passes them to the UWB ranging calculation module. This module combines these data with the transmit and receive timestamps recorded locally on the base station to calculate the ranging values ​​between the UWB module and each base station on the vehicle-mounted takeoff and landing platform. This value is then passed to the flight posture calculation module.

[0065] The flight attitude calculation module processes input information, including the UWB module's ranging values, the vehicle-mounted takeoff and landing platform's inertial sensor data, and the drone's inertial sensor data, by running an error-state Kalman filter. After calculation, the module obtains the drone's attitude and velocity information in the vehicle-mounted takeoff and landing platform's coordinate system and passes it to the flight control module for processing. The flight control module uses the vehicle-mounted takeoff and landing platform's center point as the landing target and, using distance-based PID (Proportional Integral Derivative) control, guides the drone to a safe landing on the platform.

[0066] During this process, the inertial navigation solution of the inertial sensor provides the drone's attitude information, while the ranging information of the ultra-wideband module provides increasingly accurate position solution results during the drone's approach, ultimately achieving reliable autonomous landing.

[0067] In some embodiments, the process of taking off and landing of the drone during a mission is as follows: Figure 7 As shown. Figure 7In the embodiment shown, before takeoff, the drone is located on the take-off and landing platform, and the position of the geodetic coordinate system where the take-off and landing platform is initially located is the origin, and a navigation coordinate system (n-frame) is established, which is called the "initial coordinate system". After the mission begins, the drone first listens to the ultra-wideband signal sent by the base station, establishes time synchronization with the base station, and performs ranging and communication with the ultra-wideband base station module in a time-division manner. After that, the drone continuously solves the inertial navigation posture during the mission. When the ranging information of the ultra-wideband base station module can be obtained, the ranging information is used to perform observation updates, such as Kalman filter observation updates. When the drone completes the mission, it enters the autonomous landing phase, first flying back to the effective range of the local space-time reference of the take-off and landing platform, ensuring that the ranging and communication link is established with the ultra-wideband base station module and completing clock synchronization, then sending the ultra-wideband ranging signal in the allocated time slot, using the ranging signal to measure the distance, continuously solving the inertial navigation posture and filtering and updating the ultra-wideband ranging observation, and at the same time controlling the drone to fly to the landing position of the take-off and landing platform according to the solved posture until the landing is completed. In one embodiment, after establishing a ranging and communication connection with the UWB base station module, the drone adjusts its transmit power based on its calculated distance to the takeoff and landing platform to ensure reliable ranging accuracy. If it does not detect data frames transmitted by the UWB base station module, the drone remains silent.

[0068] Figure 8 FIG. 1 is a schematic diagram of a drone performing ultra-wideband ranging according to an embodiment of the present application. Figure 1 In the system shown, there are eight sets of distances between the landing platform and the drone, denoted as Rmn, where m = 1, 2, 3, 4, and n = 1, 2. The distance values ​​do not distinguish between coordinate systems. Figure 8 The relationship between the timestamps from Am to Tn is given. Every time the UWB tag module Tn on the drone receives a data frame from Am, it records the receiving timestamp (t 10 ), and parse the two timestamps transmitted in the frame (such as t8 and t9 in the figure) and send them to the ultra-wideband ranging solution module. The ultra-wideband ranging solution module uses the three timestamps obtained this time and the seven timestamp information recorded previously (t1, t2, t3, t4, t5, t6, t7 in the figure) to calculate and obtain the local time t of node Tn. 10 The distance r9 between the two nodes (any ultra-wideband base station module and any ultra-wideband tag module) at this time.

[0069] In a specific embodiment, the specific description of the solution is as follows:

[0070] Assume that the relative motion between Am and Tn is from t1 to t 10Keep the acceleration constant, let the relative velocity at time t1 be v, the acceleration be α, and the clock drift of Am relative to Tn be δ A , the speed of light is c. Then:

[0071] Hx=y

[0072] in:

[0073]

[0074] or,

[0075]

[0076]

[0077] We can solve it by least squares: x=(H T H) -1 H T y.

[0078] Among them, 10 consecutive time stamps t1 to t 10 The following arrangement conditions can be met: t1, t5 and t9 represent the sending timestamps of the data frames sent by the ultra-wideband base station module, t2, t6 and t 10 It indicates the timestamp when the UWB tag module receives the data frame from the UWB base station module. t3 and t7 indicate the timestamp when the UWB tag module sends the data frame. t4 and t8 indicate the timestamp when the UWB base station module receives the data frame sent by the UWB tag module.

[0079] It should be noted that, in addition to the above calculation method, other calculation methods can be used to calculate the distance between any ultra-wideband base station module and any ultra-wideband tag module, as long as 10 consecutive timestamps meet the above arrangement conditions.

[0080] exist Figure 8 Among them, SS-TWR (Single-Sided Two-Way Ranging) ranging and DS-TWR (Double-Sided Two-Way Ranging) ranging are existing ranging methods. The calculation methods of these ranging methods are different from the methods mentioned above in this application, and the influence of the movement of the take-off and landing platform is not considered in the calculation process. The solution of this application takes into account the influence of the movement of the take-off and landing platform, and the ranging accuracy obtained is higher.

[0081] according to Figure 1In the system shown, the ultra-wideband ranging solution module solves and obtains 8 groups of ranging results Rmn, m=1, 2, 3, 4, n=1, 2, all of which are sent to the UAV's flight posture solution module. At the same time, the inertial sensor on the UAV fuselage also sends sensor data to the flight posture solution module, and the inertial sensor data on the take-off and landing platform obtained by the ultra-wideband communication module from the received data frame is also sent to the flight posture solution module. An error state Kalman filter can be maintained inside the flight posture solution module to solve the posture. In a specific embodiment, the internal process of the flight posture solution module is as follows. Figure 9 shown.

[0082] In the flight posture calculation module, three types of data usually need to be processed, namely the IMU data of the take-off and landing platform (or IMU data and odometer data), ultra-wideband ranging data, and the IMU data of the drone itself.

[0083] like Figure 9 As shown, the IMU data of the take-off and landing platform first enters the data preprocessing module to remove illegal data and eliminate deterministic errors based on pre-calibrated parameters. After that, it can be optionally sent to the posture estimation unit of the flight posture solution module in the take-off and landing platform together with the odometer data. This unit uses these two types of data to perform Kalman filtering on the vehicle-mounted take-off and landing platform's motion position, and uses horizontal motion constraints to perform observation updates, that is, the observations of the roll angle and pitch angle are set to 0 and updated. The output after the solution is completed is the posture of the take-off and landing platform relative to the initial point (n-frame) in, Indicates the position relationship of the take-off and landing platform in the current coordinate system (c-frame) relative to the n-frame. and Indicates the position on the coordinate axis, Indicates angles, including roll and pitch angles.

[0084] In this step, the position and posture of the take-off and landing platform in the initial coordinate system of the take-off and landing platform are obtained according to the inertial sensor data of the take-off and landing platform.

[0085] The UWB ranging data (corresponding to the above-mentioned "ranging value") is also first subjected to illegal data removal and ranging correction of variables such as distance and direction based on calibration parameters. The data is then sent to the UWB position calculation unit. This unit uses the least squares method to calculate the position of the UWB tag in the current coordinate system (c-frame) of the take-off and landing platform from multiple ranging values.

[0086] In this step, the first position information of the ultra-wideband tag module in the current coordinate system of the take-off and landing platform is determined according to the ranging value.

[0087] This position is then sent to the coordinate system conversion unit based on Complete the conversion from c-frame to n-frame and output the position of the UAV UWB tag module at the initial point (n-frame)

[0088] In this step, according to the posture of the take-off and landing platform and first location information Determine the second position information of the ultra-wideband tag module in the initial coordinate system of the take-off and landing platform

[0089] The drone's IMU data also first enters the data preprocessing module, where illegal data is removed and deterministic errors are eliminated based on pre-calibrated parameters. It is then fed into the inertial navigation pre-integration unit, which outputs the INS's pre-integrated position and velocity relative to the initial point (n-frame). This position and velocity are fed into the Kalman filter, whose state variables are the drone's position and sensor bias over n-frame.

[0090] As the observation of the filter, the filter state is updated. When updating, the relative position (arm vector) between the UWB tag and the center of the drone (for example, the coordinate center of the drone's IMU) needs to be taken into account. Finally, the position and velocity of the drone (denoted by "d") in the initial coordinate system of the take-off and landing platform in n-frame are output. in, Indicates the attitude angle of the UAV in the initial coordinate system of the take-off and landing platform, Indicates the pitch angle; Indicates the roll angle; Indicates the heading angle; Indicates the speed of the UAV in the initial coordinate system of the take-off and landing platform, represents the x-direction velocity component; represents the velocity component in the y direction; represents the z-direction velocity component.

[0091] In this step, according to the second location information Determine the first position of the center of the UAV in the initial coordinate system of the take-off and landing platform

[0092] This pose is then based on the pose of the take-off and landing platform relative to the initial point (n-frame) Perform coordinate system transformation and output the position and speed of the drone in the current coordinate system (c-frame) of the take-off and landing platform

[0093] In this step, according to the posture of the take-off and landing platform and the first pose, determine the second pose of the center of the UAV in the current coordinate system of the take-off and landing platform

[0094] The flight posture calculation module obtains the posture and speed of the UAV in the coordinate system of the vehicle-mounted take-off and landing platform.

[0095] Furthermore, in order to facilitate the use of the flight control module, it can also be converted into the position and velocity of the vehicle take-off and landing platform coordinate system in the drone body coordinate system. The conversion can be obtained by first reverse translation and then inverting the rotation matrix.

[0096] In this step, the position and posture of the take-off and landing platform in the UAV body coordinate system is determined according to the second position and posture.

[0097] The flight control module of the UAV is based on the position of the vehicle-mounted take-off and landing platform in the UAV coordinate system. As the target point, perform target-based distance PID control until landing is completed.

[0098] In the UAV posture solution, according to some optional embodiments, the UAV's posture can also be solved separately through AHRS (Attitude and Heading Reference System) technology, and the state of ESKF (Error State Kalman Filter) only includes the position and velocity of the UAV, and the UAV's posture is used as external known data in the filtering process.

[0099] Based on the above description, according to one aspect of the present application, a method for guiding autonomous landing of a drone is provided. Figure 10 As shown, the method includes the following steps:

[0100] Step S1001: receiving, from the landing platform, within a preset time slot of the current superframe, a reception timestamp of a data frame sent by the n ultra-wideband tag modules and received by the m ultra-wideband base station modules thereof, a transmission timestamp of a data frame sent by the m ultra-wideband base station modules in the current superframe, and inertial sensor data of the landing platform, where m and n are both greater than or equal to 1;

[0101] Step S1002, calculating the ranging value between the UAV and the take-off and landing platform according to the receiving timestamp, the sending timestamp, the timestamps of the n ultra-wideband tag modules sending data frames, and the timestamps of the n ultra-wideband tag modules receiving data frames from the m ultra-wideband base station modules;

[0102] Step S1003, calculating the attitude information of the UAV according to the ranging value, the inertial sensor data of the take-off and landing platform, and the inertial sensor data of the UAV; and

[0103] Step S1004: Control the drone to complete landing according to the attitude information of the drone.

[0104] According to another aspect of the present application, a method for guiding autonomous landing of a drone executed by a take-off and landing platform is provided. Figure 11 As shown, the method includes the following steps:

[0105] Step S1101: Send, within a preset time slot of the current superframe, the reception timestamps of the data frames sent by the n ultra-wideband tag modules of the drone, the transmission timestamps of the data frames sent by the m ultra-wideband base station modules, and the inertial sensor data of the take-off and landing platform, wherein m and n are both greater than or equal to 1, so that the drone calculates the ranging value between the drone and the take-off and landing platform based on the reception timestamp, the transmission timestamp, the timestamps of the data frames sent by the n ultra-wideband tag modules, and the timestamps of the data frames received by the n ultra-wideband tag modules from the m ultra-wideband base station modules, and calculates the attitude information of the drone based on the ranging value, the inertial sensor data of the take-off and landing platform, and the inertial sensor data of the drone;

[0106] Step S1102, receiving ranging values ​​from the n ultra-wideband tag modules; and

[0107] Step S1103: Adjust the power of sending data frames according to the ranging value.

[0108] The guidance method and system for autonomous landing of drones provided in this application use ultra-wideband technology to build a spatiotemporal reference system that can achieve high-precision autonomous positioning in a local coordinate system, and combine the inertial sensors on the drone and the vehicle-mounted take-off and landing platform for data fusion, thereby realizing the posture determination and flight control of the drone during the landing phase. Unlike traditional methods, this solution does not rely on the satellite navigation system to provide global coordinate positions, nor does it require visual sensors for guidance. Therefore, even in harsh environments such as at night, in bad weather, or where satellite navigation signals are limited, drones can still achieve autonomous take-off and landing. In addition, the solution also supports autonomous landing of drones on mobile take-off and landing platforms, greatly expanding the applicable scenarios for drone missions.

[0109] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0110] It should be noted that for the aforementioned method embodiments, for the sake of simplicity, they are all expressed as a series of action combinations, but those skilled in the art should be aware that this application is not limited by the order of the actions described, because according to this application, certain steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in this specification are all optional embodiments, and the actions and modules involved are not necessarily required by this application.

[0111] In the several embodiments provided in this application, it should be understood that the disclosed devices can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, and the indirect coupling or communication connection of the devices or units can be electrical connection or other forms.

[0112] See Figure 12 , Figure 12 An electronic device is provided, comprising a processor, a memory, and a sensor. The sensor is used to measure gravitational acceleration information of a mobile terminal. The memory stores computer instructions or one or more programs. When the computer instructions or one or more programs are executed by the processor, the processor executes the computer instructions to achieve the following. Figure 10 and Figure 11 The method and refinement scheme shown.

[0113] It should be understood that the above-described device embodiments are merely illustrative, and the devices disclosed herein may also be implemented in other ways. For example, the division of units / modules described in the above-described embodiments is merely a logical functional division, and actual implementations may employ alternative divisions. For example, multiple units, modules, or components may be combined or integrated into another system, or some features may be omitted or not implemented.

[0114] In addition, unless otherwise specified, the functional units / modules in the various embodiments of the present invention may be integrated into a single unit / module, each unit / module may exist physically separately, or two or more units / modules may be integrated together. The aforementioned integrated units / modules may be implemented in the form of hardware or software program modules.

[0115] If the integrated unit / module is implemented in hardware, the hardware may be a digital circuit, an analog circuit, or the like. The physical implementation of the hardware structure includes, but is not limited to, transistors, memristors, and the like. Unless otherwise specified, the processor or chip may be any appropriate hardware processor, such as a CPU, GPU, FPGA, DSP, and ASIC. Unless otherwise specified, the on-chip cache, off-chip memory, and storage may be any appropriate magnetic storage medium or magneto-optical storage medium, such as resistive random access memory (RRAM), dynamic random access memory (DRAM), static random access memory (SRAM), enhanced dynamic random access memory (EDRAM), high-bandwidth memory (HBM), hybrid memory cube (HMC), and the like.

[0116] If the integrated unit / module is implemented in the form of a software program module and sold or used as an independent product, it can be stored in a computer-readable memory. Based on this understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a memory, including a number of instructions for enabling a computer electronic device (which can be a personal computer, a server or a network electronic device, etc.) to perform all or part of the steps of the method described in each embodiment of the present disclosure. The aforementioned memory includes: various media that can store program codes, such as a U disk, a read-only memory (ROM), a random access memory (RAM), a mobile hard disk, a magnetic disk or an optical disk.

[0117] The embodiment of the present application further provides a computer-readable storage medium storing one or more computer programs, which, when executed by multiple processors, causes the processors to execute the following Figure 10 and Figure 11 The method and refinement scheme shown.

[0118] An embodiment of the present application also provides a computer program product, comprising a computer program, which, when executed on a computer, causes the computer to execute the method for guiding autonomous landing of a drone according to any of the above embodiments.

[0119] References to features, advantages, or similar language throughout this specification do not imply that all features and advantages achievable with this solution are included or embodied in any single implementation thereof. Rather, language referring to features and advantages is understood to mean that a specific feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of this solution. Therefore, discussions of features, advantages, and similar language throughout this specification may, but do not necessarily, refer to the same embodiment.

[0120] Furthermore, the features, advantages, and characteristics of the present invention may be combined in any suitable manner in one or more embodiments. Based on the description herein, one of ordinary skill in the relevant art will recognize that the present invention may be practiced without one or more of the specific features or advantages of a particular embodiment. In other cases, additional features and advantages may be realized in a particular embodiment that is not presented in all embodiments of the present invention.

[0121] The embodiments of the present application are described in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only intended to help understand the method and core ideas of the present application. At the same time, changes or modifications made by those skilled in the art based on the ideas of the present application, the specific implementation methods, and the scope of application of the present application, all fall within the scope of protection of the present application. In summary, the contents of this specification should not be construed as limiting the present application.

Claims

1. A method for guiding autonomous landing of a UAV, applied to a UAV, characterized in that: The drone includes n ultra-wideband tag modules, and the method includes: In a preset time slot of the current superframe, receiving from the take-off and landing platform the reception timestamp of the data frames sent by the n ultra-wideband tag modules received by the m ultra-wideband base station modules, the transmission timestamp of the data frames sent by the m ultra-wideband base station modules in the current superframe, and the inertial sensor data of the take-off and landing platform, where m and n are both greater than or equal to 1; Calculate the distance value between the UAV and the take-off and landing platform according to the receiving timestamp, the sending timestamp, the timestamps of the n ultra-wideband tag modules sending the data frames, and the timestamps of the n ultra-wideband tag modules receiving the data frames from the m ultra-wideband base station modules; Calculating attitude information of the UAV based on the ranging value, the inertial sensor data of the take-off and landing platform, and the inertial sensor data of the UAV; and The UAV is controlled to complete landing according to the posture information of the UAV.

2. The method according to claim 1, wherein The calculating the ranging value between the UAV and the take-off and landing platform according to the receiving timestamp, the sending timestamp, the timestamp of the data frames sent by the n ultra-wideband tag modules, and the timestamp of the data frames received by the n ultra-wideband tag modules from the m ultra-wideband base station modules includes: For any one of the n ultra-wideband tag modules and any one of the m ultra-wideband base station modules, the distance between the any one ultra-wideband tag module and the any one ultra-wideband base station module is calculated based on 10 consecutive transceiver timestamps between the two, wherein the 10 consecutive transceiver timestamps include t1 to t 10 , where t1, t5 and t9 represent the timestamps of the data frames sent by any one of the ultra-wideband base station modules, t2, t6 and t 10 It indicates the timestamp when any one of the ultra-wideband tag modules receives the data frame from any one of the ultra-wideband base station modules, t3 and t7 indicate the timestamp when any one of the ultra-wideband tag modules sends the data frame, and t4 and t8 indicate the timestamp when any one of the ultra-wideband base station modules receives the data frame sent by any one of the ultra-wideband tag modules.

3. The method according to claim 1, wherein Calculating the attitude information of the UAV according to the ranging value, the inertial sensor data of the take-off and landing platform, and the inertial sensor data of the UAV includes: Obtaining the position and posture of the take-off and landing platform in the initial coordinate system of the take-off and landing platform according to the inertial sensor data of the take-off and landing platform; Determining first position information of the n ultra-wideband tag modules in a current coordinate system of the take-off and landing platform according to the ranging value; Determine second position information of the n ultra-wideband tag modules in an initial coordinate system of the take-off and landing platform according to the posture of the take-off and landing platform and the first position information; Determine the first position of the center of the UAV in the initial coordinate system of the take-off and landing platform according to the second position information; According to the posture of the take-off and landing platform and the first posture, a second posture of the center of the UAV in the current coordinate system of the take-off and landing platform is determined.

4. The method according to claim 3, wherein Also includes: Determining the posture of the take-off and landing platform in the UAV body coordinate system according to the second posture; The step of controlling the drone to land according to the attitude information of the drone includes: The UAV is controlled to complete landing according to the posture of the take-off and landing platform in the UAV body coordinate system.

5. The method according to any one of claims 1 to 4, characterized in that Also includes: In the time slot corresponding to the n ultra-wideband tag modules in the current superframe, a data frame is sent, wherein the sent data frame includes the ranging value.

6. The method according to any one of claims 1 to 4, characterized in that The superframe includes a time slots corresponding to the m ultra-wideband base station modules and the n ultra-wideband tag modules, wherein a=m+n, and the data frames sent by the main base station module among the m ultra-wideband base station modules include the reception timestamp of the data frames sent by the n ultra-wideband tag modules, the transmission timestamp of the data frames sent by the main base station module in the current superframe, and the inertial sensor data of the take-off and landing platform. When m is greater than or equal to 2, the data frames sent by any secondary base station module among the m ultra-wideband base station modules except the main base station module include the reception timestamp of the data frames sent by the n ultra-wideband tag modules and the transmission timestamp of the data frames sent by the secondary base station module in the current superframe.

7. The method according to any one of claims 1 to 4, characterized in that The n ultra-wideband tag modules are arranged on the wings of the drone. When n is greater than 1, they are respectively arranged on different wings of the drone. A first inertial sensor is arranged at the center of the drone.

8. A method for guiding autonomous landing of a UAV, applied to a take-off and landing platform, characterized in that: The take-off and landing platform includes m ultra-wideband base station modules, and the method includes: In a preset time slot of the current superframe, the receiving timestamps of the data frames sent by the n ultra-wideband tag modules of the drone, the sending timestamps of the data frames sent by the m ultra-wideband base station modules, and the inertial sensor data of the take-off and landing platform are sent, wherein m and n are both greater than or equal to 1, so that the drone calculates the ranging value between the drone and the take-off and landing platform according to the receiving timestamp, the sending timestamp, the timestamp of the data frames sent by the n ultra-wideband tag modules, and the timestamp of the data frames received by the n ultra-wideband tag modules from the m ultra-wideband base station modules, and calculates the attitude information of the drone according to the ranging value, the inertial sensor data of the take-off and landing platform, and the inertial sensor data of the drone; receiving ranging values ​​from the n ultra-wideband tag modules; and The power of sending the data frame is adjusted according to the ranging value.

9. The method according to claim 8, wherein The take-off and landing platform also includes: The second inertial sensor is arranged at the center of the take-off and landing platform.

10. A guidance system for autonomous landing of a UAV, characterized in that: include: A drone for performing the method according to any one of claims 1 to 7; as well as A take-off and landing platform for performing the method according to claim 8 or 9.

11. An electronic device comprising a memory storing one or more programs and one or more processors, the one or more processors being electrically coupled to the memory and configured to execute the one or more programs to perform the method according to any one of claims 1 to 9.

12. A computer-readable storage medium storing a computer program, wherein when the computer program is executed by a processor, the method according to any one of claims 1 to 9 is performed.

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