Methods and devices for guiding and safely landing unmanned aerial vehicles (UAVs) on ground facilities

Abstract

This invention discloses a method and apparatus for guiding and safely landing an unmanned aerial vehicle (UAV) at ground facilities, comprising the following steps: Step 1, pre-landing status verification and target locking; Step 2, remote guidance during the UAV approach phase; Step 3, visual and signal fusion guidance during the precise positioning phase; Step 4, full-process safety monitoring and attitude correction during landing; and Step 5, touchdown buffering and landing lock control. All modules of this invention are implemented using existing airborne computing platforms, without requiring ultra-large models or cloud inference. State estimation, residual calculation, phase switching, and control laws are all executed in real time. Anchor point geometry, marker geometry, and safety domain are uniformly described through ground facility parameter packages. The same UAV can quickly switch between different take-off and landing stations without manual reconfiguration each time. Wind disturbance estimation is directly incorporated into the touchdown point determination, rather than being temporarily corrected outside the controller, which helps reduce the risk of lateral drift and boundary collision.

Description

Technical Field

[0001] This invention relates to the field of autonomous control and low-altitude safe take-off and landing technology for unmanned aerial vehicles (UAVs), specifically to a method and device for guiding UAVs to land and controlling safe landing. Background Technology

[0002] In scenarios such as logistics delivery, building inspection, emergency delivery, and fixed take-off and landing station duty, drones need to land stably on take-off and landing points of limited size. Solutions relying solely on GNSS are unstable in terms of accuracy and availability under conditions of obstruction, near-ground reflection, urban canyons, or metal roofs. Solutions relying solely on visual markers are prone to loss of lock under conditions of backlight, rain, fog, partial marker obstruction, and lens contamination. UWB and IMU can compensate for problems caused by temporary visual failures, but UWB multipath propagation and poor geometry can also lead to amplified measurement bias. The real engineering difficulty is not stacking several sensors together, but determining whether the current relative pose is sufficient to support continued descent at different stages, and how to immediately maintain, realign, or go around if the conditions are not met.

[0003] Among the existing publicly available solutions, at least the following technical approaches are similar to this invention:

[0004] A) Attitude estimation scheme based on visual markers and IMU: This type of method recognizes manual markers through a monocular camera and then performs EKF fusion with an IMU to achieve relative pose estimation of the UAV in the terminal phase. However, its core is still to update when visual is visible and extrapolate the inertial navigation when visual is lost. There is a lack of clear engineering criteria for whether the multimodal expressions are consistent with each other and whether they are sufficient to continue descent.

[0005] B) Two-stage approach / landing scheme based on UWB, IMU and vision: This type of scheme has disclosed a technical framework for approaching from a distance using UWB-IMU and entering a precise terminal landing after detecting visual markers at close range, which shows that sensor stacking alone is not enough to constitute a stable creative basis.

[0006] C) Visual / inertial guidance landing schemes for ships or mobile platforms: This type of scheme emphasizes terminal guidance and platform motion compensation, but often separates wind disturbance compensation, observability judgment and go-around logic, and lacks parameter interfaces suitable for large-scale deployment of fixed ground take-off and landing facilities.

[0007] However, the above method still has the following drawbacks:

[0008] (1) When vision is normal but UWB multipath deterioration or UWB is normal but visual reprojection deviation increases sharply, the system will often continue to decline and may mistake local error measurements for true pose.

[0009] (2) When crosswinds, ground heat flow or backflow around the platform are present, control based solely on the current position error cannot guarantee that the expected contact point will still fall within the safe zone;

[0010] (3) The lack of a unified parameter description between take-off and landing facilities and UAVs makes anchor point geometry, marker geometry, coordinate system definition and safety domain boundary often rely on offline manual solidification, which is not conducive to large-scale deployment;

[0011] (4) The post-lockout handling strategy is too coarse, usually only offering two options: hovering and retrying or returning to base, lacking a fine-grained decision chain for maintaining altitude, realigning, and going around. Summary of the Invention

[0012] The purpose of this invention is to provide a method and apparatus for guiding and safely controlling the landing of unmanned aerial vehicles (UAVs) at ground facilities. This addresses the issues raised in the background art, such as: when vision is normal but UWB multipath propagation is deteriorating, or when UWB is normal but visual reprojection deviation increases sharply, the system often continues to descend, easily mistaking local erroneous measurements for the true pose; when crosswinds, ground heat flow, or backflow around the platform are present, control is based solely on the current position error, failing to guarantee that the expected touchdown point will still fall within the safe zone; the lack of a unified parameter description between the takeoff and landing facilities and the UAV means that anchor point geometry, marker geometry, coordinate system definition, and safe zone boundaries often rely on offline manual fixing, which is detrimental to large-scale deployment; and the overly coarse post-lockdown handling strategy, typically offering only hovering retry or return-to-home options, lacking a fine-grained decision chain for maintaining altitude realignment and re-flying.

[0013] To achieve the above objectives, the present invention provides the following technical solution: a control method for a drone landing ground facility guidance and safe landing control device, comprising the following steps:

[0014] Step 1: Pre-landing Status Verification and Target Lock-in: After the ground landing facility is activated, it uploads its own position, status, and landing authorization to the low-altitude control platform in real time, while continuously transmitting a dedicated guidance reference signal; after receiving the return landing command, the UAV first completes a self-check of its own power, sensors, and communication modules. If the self-check is successful, it locks onto the target ground landing facility through the low-altitude control platform, obtains the facility's precise coordinates and guidance signal frequency band, and completes the landing target lock-in; if the self-check is abnormal, the UAV immediately hovers and sends a fault alarm, terminating the landing process;

[0015] Step 2, Remote Guidance During the Approach Phase: The drone flies over the target ground landing facility and, upon entering the approach area, switches to the ground facility's remote guidance mode. The ground landing facility sends real-time position correction data to the drone through its positioning enhancement module and wireless communication module. Combined with the drone's own RTK positioning, coarse positioning calibration is completed, the optimal approach and landing route is planned, and the drone is controlled to smoothly descend to the preset landing hovering altitude. During this phase, environmental monitoring is simultaneously activated to collect real-time data on wind speed, wind direction, and precipitation. If environmental parameters exceed the safe landing threshold, the drone is controlled to remain hovering and wait until the environmental conditions are met or the emergency landing procedure is initiated.

[0016] Step 3: Precise Positioning Stage - Visual and Signal Fusion Guidance: After the UAV reaches the preset hovering altitude, it activates the onboard visual recognition module to capture the unique visual markers on the ground landing facility, while simultaneously receiving high-precision short-range guidance signals transmitted by the ground facility. A visual positioning and radio frequency guidance fusion positioning algorithm is used to calculate the relative position and attitude deviation between the UAV and the landing center point, eliminating single positioning interference data and achieving centimeter-level precise positioning. During the positioning process, image quality is optimized in real time, and visual images in strong and low light environments are equalized to ensure that positioning accuracy is not affected under complex lighting conditions.

[0017] Step 4: Safety Monitoring and Attitude Correction Throughout the Landing Process: As the drone begins its vertical descent, ground facilities and the drone simultaneously initiate safety monitoring. The drone monitors its own flight attitude, altitude, descent rate, and power reserve in real time. Ground facilities use radar and visual sensors to monitor obstacles in the landing area and the drone's landing trajectory, simultaneously feeding back the monitoring data to the drone controller. Based on the real-time monitored position and attitude deviations, a PID control algorithm with compensation is used to dynamically adjust the drone's rotor speed and flight attitude, correcting the landing trajectory in real time to ensure that the drone always descends along the vertical line of the landing center, eliminating the risk of lateral deviation.

[0018] Step 5, Ground Buffer and Landing Lock Control: When the UAV descends to a height close to the ground facility's touchdown height, it automatically reduces its descent rate and initiates soft landing buffer control to reduce the impact force upon touchdown. After the UAV touches down, the ground facility immediately triggers the landing lock mechanism, securing the UAV's landing gear through mechanical positioning or electromagnetic adsorption, while simultaneously cutting off the UAV's power. The ground facility simultaneously uploads a landing success signal, completing the entire landing process.

[0019] Step Six: Emergency Safety Handling for Abnormal Situations: During the entire landing process, if the positioning signal is interrupted, the drone loses attitude control, obstacles appear in the landing area, power is insufficient, or there are sudden abnormal environmental changes, the system will immediately activate emergency control: If it is in the approach phase, control the drone to climb to a safe altitude and hover; if it is in the precision landing phase, control the drone to hover urgently and reposition; if a serious malfunction occurs, initiate the nearest safe emergency landing or low-altitude slow descent procedure to minimize equipment damage and safety accidents.

[0020] As a further technical solution of the present invention, the error state vector of the UAV in step two is defined as follows:

[0021] ,

[0022] Where, p k v represents the position of the drone relative to its take-off and landing point. k Let q be the relative velocity. k Let b be a quaternion of attitude. a,k and b ，k These are the accelerometer and gyroscope zero bias, respectively. k Here is the estimate of the lateral wind disturbance; the discrete propagation equation based on the IMU is written as:

[0023]

[0024] Among them, u k This represents the measurement input of the IMU at time k. The sampling period provides high-frequency predictions of the propagation results, but these are not directly used as the basis for allowing a decrease. The UWB measurement model is as follows:

[0025] ,

[0026] in, Let i be the position of the i-th UWB anchor point in the take-off and landing point coordinate system. For systematic bias terms, For random noise, the visual reprojection model is:

[0027] ,

[0028] in, Here, K is the camera projection operator, and K is the intrinsic parameter matrix. Let m be the camera-relative takeoff and landing point transformation matrix derived from the airborne state. j Let be the homogeneous coordinates of the j-th visual marker in the take-off and landing coordinate system.

[0029] As a further technical solution of the present invention, the PID control algorithm with compensation term in step four is specifically as follows:

[0030] 4.1 Ground Facility Parameter Package and Synchronization Interface: The parameter package output by the ground facility preferably includes:

[0031] Take-off and landing point markings The parameters are the version number (ver), timestamp (t0), and valid window. UWB anchor set Visual marker geometric set safety zone boundary of take-off and landing point Stage speed limit Along with the attitude limit and the ground capability bitmap Ccap, it is used to declare whether wind field assistance, light assistance or backup guidance is supported. After receiving the parameter package, the UAV performs timestamp and version verification, and only loads the parameter package if it is within the valid time window; if the version changes, the coordinate system reset and anchor point geometry consistency verification are completed first before proceeding to the next step.

[0032] 4.2 Multimodal measurement acquisition and time alignment: The UAV acquires IMU, altitude, UWB and visual measurements respectively. Preferably, the IMU sampling frequency is 100Hz to 400Hz, the UWB update frequency is 20Hz to 100Hz, and the camera frame rate is 20fps to 60fps. Time synchronization adopts a combination of nearest neighbor interpolation and extrapolation to ensure that UWB and visual measurements are aligned with the IMU propagation timeline, avoiding mistaking old measurements for new measurements due to time misalignment during rapid descent.

[0033] 4.3 Error State Fusion and Modal Adaptive Update: In each fusion cycle, the system first performs IMU pre-integration propagation, then performs UWB update and visual update based on the measured data. If vision is temporarily unavailable, only UWB update is retained. If the whitening residual of UWB continues to increase, its update weight is reduced, and vision / IMU becomes the dominant factor. Preferably, the adaptive weight is written as:

[0034] ,

[0035] in, and These represent the normalized residual energy of UWB and visual modality, respectively;

[0036] 4.4 Phase Integrity Assessment and Protected Descent: The landing process is divided into four phases: approach phase, alignment phase, descent phase, and touchdown phase. Each phase corresponds to different integrity thresholds and velocity constraints.

[0037] 4.5 Wind disturbance estimation and compensation: Lateral wind disturbance is estimated by combining changes in airframe speed, visual ground drift and UWB position residuals. When the wind disturbance amplitude continues to rise but has not yet triggered the go-around threshold, the controller first compensates through feedforward terms. If the wind disturbance causes the value to exceed the safety margin, the descent is paused and the aircraft waits for realignment or transfer to a backup take-off and landing point.

[0038] 4.6 Ground contact confirmation and fallback: Ground contact confirmation does not use a single ground contact switch, but uses a combination of altitude, vertical velocity, attitude change rate and short-term vibration response for judgment. If the ground contact conditions are not met, but the altitude is already close to the ground, then the landing will enter the slow descent hold phase. If both visual and UWB fail for more than the set time, the landing process will be directly terminated and the aircraft will go around.

[0039] Unmanned aerial vehicle (UAV) landing guidance and safe landing control system, including UAV fuselage and systems.

[0040] The drone's casing has mounting bases fixedly installed at both ends on both sides. An angle rod is rotatably connected to one end of each of the four mounting bases. A motor base is fixedly installed at one end of each of the four angle rods. A flight propeller is provided on one side of each of the four motor bases.

[0041] The system includes ground landing facilities and a drone platform. The ground-side module is located on the ground facility side, and the airborne module is located on the drone side.

[0042] As a further technical solution of the present invention, the ground terminal module includes a main control unit, a guidance signal transmission module, a visual identification module, an environmental monitoring module, an obstacle monitoring radar, a mechanical locking unit, a wireless communication unit, and a power management module;

[0043] The main control unit is the core control component on the ground, responsible for coordinating the operation of various modules, analyzing UAV status data, issuing guidance commands, and controlling emergency protection actions. The guidance signal transmission module adopts a fusion transmission mode of radio frequency and positioning enhancement, providing coarse positioning guidance signals remotely and high-precision calibration signals at close range. The visual identification module uses a dedicated identification with high contrast and strong light interference resistance, combined with a supplementary lighting unit, to adapt to all-weather visual recognition. The environmental monitoring module collects environmental parameters such as wind speed, temperature, humidity, and precipitation in real time to determine the safety of the landing environment. The obstacle monitoring radar scans the landing area in real time to identify obstacle risks. The mechanical locking unit is used to quickly fix the UAV body after it touches the ground to prevent slippage and overturning. The wireless communication unit realizes three-way data interaction between ground facilities, UAV, and low-altitude control platform to ensure real-time signal transmission. The power management module provides stable power supply for the entire ground device and supports dual-mode switching between mains power and backup power.

[0044] As a further technical solution of the present invention, the airborne terminal module includes an airborne main control chip, a signal receiving module, an airborne vision sensor, an attitude monitoring unit, a data processing unit, an emergency control unit, and a communication module;

[0045] The airborne main control chip is responsible for receiving ground guidance signals, parsing control commands, and outputting flight attitude adjustment commands; the signal receiving module is paired with the ground guidance signal transmitting module to receive guidance and positioning correction data in real time; the airborne visual sensor is used to capture ground visual markers and complete visual positioning calculations; the attitude monitoring unit collects UAV flight attitude, altitude, descent rate, and power margin data in real time; the data processing unit is equipped with a fusion positioning algorithm and attitude correction algorithm to quickly calculate position deviations and generate control parameters; the emergency control unit is used to trigger emergency hovering and emergency landing actions in abnormal situations; the communication module ensures real-time data interaction between the airborne end, the ground end, and the control platform, achieving full information synchronization.

[0046] As a further technical solution of the present invention, a stepper motor is fixedly installed at the bottom of each of the four mounting bases, and the output end of each of the four stepper motors is fixedly connected to the side of the angle rod directly opposite to it. The stepper motor drives the angle rod to rotate, thereby adjusting the flight angle of the propeller.

[0047] As a further technical solution of the present invention, a servo motor is fixedly installed on one side of each of the four motor bases, and the output end of each of the four servo motors is fixedly connected to one end of each of the four propellers. The servo motors drive the propellers to rotate, which facilitates the take-off of the UAV.

[0048] Compared with the prior art, the beneficial effects of the present invention are:

[0049] 1. All modules are implemented using existing airborne computing platforms, without requiring ultra-large models or cloud inference; state estimation, residual calculation, phase switching, and control laws are all executed in real time; anchor point geometry, marker geometry, and safety domain are uniformly described through ground facility parameter packages, allowing the same UAV to switch quickly between different take-off and landing stations without manual reconfiguration each time; wind disturbance estimation is directly incorporated into the touch point determination, rather than being temporarily corrected outside the controller, which helps reduce the risk of lateral drift and boundary collision.

[0050] 2. Construct a full-process status monitoring and emergency response system for landing, avoid obstacles, attitude loss, and sudden environmental changes in real time, and prevent safety accidents caused by landing collisions, overturning, and power interruption; the ground facilities and UAVs are controlled in two-way collaboratively, and the landing is completed autonomously without human intervention; the device has a modular structure, is compatible with various fixed and mobile ground landing facilities, is easy to install and deploy, and is compatible with the use of multiple UAV models. Attached Figure Description

[0051] Figure 1 This is a top view of the present invention;

[0052] Figure 2 This is a schematic diagram of the system architecture of the present invention;

[0053] Figure 3 This is a schematic diagram of the architecture of the airborne terminal module of the present invention;

[0054] Figure 4 This is a flowchart of the present invention;

[0055] Figure 5 This is a schematic diagram of the overall structure of the UAV precision landing system of the present invention;

[0056] Figure 6 This is the phase state machine and integrity gating diagram for the precise landing of the UAV in this invention;

[0057] Figure 7 This is a confidence ellipse diagram for the safe landing area and contact point of the present invention.

[0058] In the picture: 1. UAV shell; 2. Mounting base; 3. Angle rod; 4. Motor base; 5. Servo motor; 6. Propeller; 7. Stepper motor. Detailed Implementation

[0059] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0060] Please see Figure 1-7 This invention provides a control method for a drone landing ground facility guidance and safe landing control device, comprising the following steps:

[0061] Step 1: Pre-landing Status Verification and Target Lock-in: After the ground landing facility is activated, it uploads its own position, status, and landing authorization to the low-altitude control platform in real time, while continuously transmitting a dedicated guidance reference signal; after receiving the return landing command, the UAV first completes a self-check of its own power, sensors, and communication modules. If the self-check is successful, it locks onto the target ground landing facility through the low-altitude control platform, obtains the facility's precise coordinates and guidance signal frequency band, and completes the landing target lock-in; if the self-check is abnormal, the UAV immediately hovers and sends a fault alarm, terminating the landing process;

[0062] Step 2, Remote Guidance During the Approach Phase: The drone flies over the target ground landing facility and, upon entering the approach area, switches to the ground facility's remote guidance mode. The ground landing facility sends real-time position correction data to the drone through its positioning enhancement module and wireless communication module. Combined with the drone's own RTK positioning, coarse positioning calibration is completed, the optimal approach and landing route is planned, and the drone is controlled to smoothly descend to the preset landing hovering altitude. During this phase, environmental monitoring is simultaneously activated to collect real-time data on wind speed, wind direction, and precipitation. If environmental parameters exceed the safe landing threshold, the drone is controlled to remain hovering and wait until the environmental conditions are met or the emergency landing procedure is initiated.

[0063] Step 3: Precise Positioning Stage - Visual and Signal Fusion Guidance: After the UAV reaches the preset hovering altitude, it activates the onboard visual recognition module to capture the unique visual markers on the ground landing facility, while simultaneously receiving high-precision short-range guidance signals transmitted by the ground facility. A visual positioning and radio frequency guidance fusion positioning algorithm is used to calculate the relative position and attitude deviation between the UAV and the landing center point, eliminating single positioning interference data and achieving centimeter-level precise positioning. During the positioning process, image quality is optimized in real time, and visual images in strong and low light environments are equalized to ensure that positioning accuracy is not affected under complex lighting conditions.

[0064] Step 4: Safety Monitoring and Attitude Correction Throughout the Landing Process: As the drone begins its vertical descent, ground facilities and the drone simultaneously initiate safety monitoring. The drone monitors its own flight attitude, altitude, descent rate, and power reserve in real time. Ground facilities use radar and visual sensors to monitor obstacles in the landing area and the drone's landing trajectory, simultaneously feeding back the monitoring data to the drone controller. Based on the real-time monitored position and attitude deviations, a PID control algorithm with compensation is used to dynamically adjust the drone's rotor speed and flight attitude, correcting the landing trajectory in real time to ensure that the drone always descends along the vertical line of the landing center, eliminating the risk of lateral deviation.

[0065] Step 5, Ground Buffer and Landing Lock Control: When the UAV descends to a height close to the ground facility's touchdown height, it automatically reduces its descent rate and initiates soft landing buffer control to reduce the impact force upon touchdown. After the UAV touches down, the ground facility immediately triggers the landing lock mechanism, securing the UAV's landing gear through mechanical positioning or electromagnetic adsorption, while simultaneously cutting off the UAV's power. The ground facility simultaneously uploads a landing success signal, completing the entire landing process.

[0066] Step Six: Emergency Safety Handling for Abnormal Situations: During the entire landing process, if the positioning signal is interrupted, the drone loses attitude control, obstacles appear in the landing area, power is insufficient, or there are sudden abnormal environmental changes, the system will immediately activate emergency control: If it is in the approach phase, control the drone to climb to a safe altitude and hover; if it is in the precision landing phase, control the drone to hover urgently and reposition; if a serious malfunction occurs, initiate the nearest safe emergency landing or low-altitude slow descent procedure to minimize equipment damage and safety accidents.

[0067] In step two, the error state vector of the UAV is defined as follows:

[0068] ,

[0069] Where, p k v represents the position of the drone relative to its take-off and landing point. k Let q be the relative velocity. k Let b be a quaternion of attitude. a,k and b ，k These are the accelerometer and gyroscope zero bias, respectively. k Here is the estimate of the lateral wind disturbance; the discrete propagation equation based on the IMU is written as:

[0070]

[0071] Among them, u k This represents the measurement input of the IMU at time k. The sampling period provides high-frequency predictions of the propagation results, but these are not directly used as the basis for allowing a decrease. The UWB measurement model is as follows:

[0072] ,

[0073] in, Let i be the position of the i-th UWB anchor point in the take-off and landing point coordinate system. For systematic bias terms, For random noise, the visual reprojection model is:

[0074] ,

[0075] in, Here, K is the camera projection operator, and K is the intrinsic parameter matrix. Let m be the camera-relative takeoff and landing point transformation matrix derived from the airborne state. j Let be the homogeneous coordinates of the j-th visual marker in the take-off and landing coordinate system.

[0076] Step four, specifically the PID control algorithm with compensation term, is as follows:

[0077] 4.1 Ground Facility Parameter Package and Synchronization Interface: The parameter package output by the ground facility preferably includes:

[0078] Take-off and landing point markings The parameters are the version number (ver), timestamp (t0), and valid window. UWB anchor set Visual marker geometric set safety zone boundary of take-off and landing point Stage speed limit Along with the attitude limit and the ground capability bitmap Ccap, it is used to declare whether wind field assistance, light assistance or backup guidance is supported. After receiving the parameter package, the UAV performs timestamp and version verification, and only loads the parameter package if it is within the valid time window; if the version changes, the coordinate system reset and anchor point geometry consistency verification are completed first before proceeding to the next step.

[0079] 4.2 Multimodal measurement acquisition and time alignment: The UAV acquires IMU, altitude, UWB and visual measurements respectively. Preferably, the IMU sampling frequency is 100Hz to 400Hz, the UWB update frequency is 20Hz to 100Hz, and the camera frame rate is 20fps to 60fps. Time synchronization adopts a combination of nearest neighbor interpolation and extrapolation to ensure that UWB and visual measurements are aligned with the IMU propagation timeline, avoiding mistaking old measurements for new measurements due to time misalignment during rapid descent.

[0080] 4.3 Error State Fusion and Modal Adaptive Update: In each fusion cycle, the system first performs IMU pre-integration propagation, then performs UWB update and visual update based on the measured data. If vision is temporarily unavailable, only UWB update is retained. If the whitening residual of UWB continues to increase, its update weight is reduced, and vision / IMU becomes the dominant factor. Preferably, the adaptive weight is written as:

[0081] ,

[0082] in, and These represent the normalized residual energy of UWB and visual modality, respectively;

[0083] 4.4 Phase Integrity Assessment and Protected Descent: The landing process is divided into four phases: approach phase, alignment phase, descent phase, and touchdown phase. Each phase corresponds to different integrity thresholds and velocity constraints.

[0084] 4.5 Wind disturbance estimation and compensation: Lateral wind disturbance is estimated by combining changes in airframe speed, visual ground drift and UWB position residuals. When the wind disturbance amplitude continues to rise but has not yet triggered the go-around threshold, the controller first compensates through feedforward terms. If the wind disturbance causes the value to exceed the safety margin, the descent is paused and the aircraft waits for realignment or transfer to a backup take-off and landing point.

[0085] 4.6 Ground contact confirmation and fallback: Ground contact confirmation does not use a single ground contact switch, but uses a combination of altitude, vertical velocity, attitude change rate and short-term vibration response for judgment. If the ground contact conditions are not met, but the altitude is already close to the ground, then the landing will enter the slow descent hold phase. If both visual and UWB fail for more than the set time, the landing process will be directly terminated and the aircraft will go around.

[0086] A drone landing guidance and safe landing control device, comprising a drone fuselage 1 and a system,

[0087] The drone casing 1 has mounting bases 2 fixedly installed at both ends on both sides. Angle rods 3 are rotatably connected to one end of each of the four mounting bases 2. Motor bases 4 are fixedly installed at one end of each of the four angle rods 3. A flight propeller 6 is provided on one side of each of the four motor bases 4.

[0088] The system includes ground landing facilities and a drone platform. The ground-side module is located on the ground facility side, and the airborne module is located on the drone side.

[0089] The ground module includes a main control unit, a guidance signal transmission module, a visual identification module, an environmental monitoring module, an obstacle monitoring radar, a mechanical locking unit, a wireless communication unit, and a power management module;

[0090] The main control unit is the core control component on the ground, responsible for coordinating the operation of various modules, analyzing UAV status data, issuing guidance commands, and controlling emergency protection actions. The guidance signal transmission module adopts a fusion transmission mode of radio frequency and positioning enhancement, providing coarse positioning guidance signals remotely and high-precision calibration signals at close range. The visual identification module uses exclusive high-contrast, strong light interference-resistant identification, combined with a supplementary lighting unit, to adapt to all-weather visual recognition. The environmental monitoring module collects environmental parameters such as wind speed, temperature, humidity, and precipitation in real time to determine the safety of the landing environment. The obstacle monitoring radar scans the landing area in real time to identify obstacle risks. The mechanical locking unit is used to quickly fix the UAV after it touches the ground to prevent slippage and overturning. The wireless communication unit realizes three-way data interaction between ground facilities, UAVs, and low-altitude control platforms to ensure real-time signal transmission. The power management module provides stable power supply for the entire ground device and supports dual-mode switching between mains power and backup power.

[0091] The airborne module includes an airborne main control chip, a signal receiving module, an airborne vision sensor, an attitude monitoring unit, a data processing unit, an emergency control unit, and a communication module;

[0092] The airborne main control chip is responsible for receiving ground guidance signals, parsing control commands, and outputting flight attitude adjustment commands; the signal receiving module is paired with the ground guidance signal transmitting module to receive guidance and positioning correction data in real time; the airborne visual sensor is used to capture ground visual markers and complete visual positioning calculations; the attitude monitoring unit collects real-time data on the UAV's flight attitude, altitude, descent rate, and power margin; the data processing unit is equipped with a fusion positioning algorithm and attitude correction algorithm to quickly calculate position deviations and generate control parameters; the emergency control unit is used to trigger emergency hovering and emergency landing actions in abnormal situations; the communication module ensures real-time data interaction between the airborne end, the ground end, and the management platform, achieving full information synchronization.

[0093] Each of the four mounting bases 2 has a stepper motor 7 fixedly mounted on its bottom end, and the output ends of the four stepper motors 7 are fixedly connected to the side of the angle rod 3 that is directly opposite to it.

[0094] In use, the stepper motor 7 drives the angle lever 3 to rotate, thereby adjusting the flight angle of the propeller 6.

[0095] Each of the four motor bases 4 has a servo motor 5 fixedly installed on one side, and the output ends of the four servo motors 5 are fixedly connected to the opposite ends of the four propellers 6.

[0096] When in use, the servo motor 5 drives the propeller 6 to rotate, making it easier for the drone to take off.

[0097] Example 1:

[0098] In this invention, the airborne module is equipped with a power line inspection drone that performs autonomous landing operations: After completing the power line inspection, the drone receives a return command, completes its own power and sensor self-checks, and locks onto the target hangar after passing the self-check; after flying to the approach area above the hangar, it receives the RTK enhanced positioning signal transmitted by the hangar, completes coarse positioning, and descends to a hovering height of 2 meters; the airborne visual sensor captures the hangar's exclusive Apriltag visual markers, combines them with radio frequency short-range guidance signals, and calculates the position deviation through a fusion algorithm, with the deviation value controlled within 1 cm; during the drone's vertical descent, the hangar radar monitors the landing area in real time to ensure there are no obstacles, and the drone corrects its attitude in real time to maintain a smooth descent; when approaching the ground, the descent rate is reduced to 0.2 m / s, achieving a soft landing; after touchdown, the hangar's mechanical positioning claws quickly fix the drone's landing gear, the drone cuts off power, and the hangar uploads landing success information. The entire landing process takes 30 seconds, and the accuracy and safety meet the requirements of all-weather inspection operations.

[0099] Example 2:

[0100] In this invention, in low-light conditions at night, the UAV performs logistics delivery landing operations: the ground landing facility's supplementary lighting unit automatically turns on to improve the visual recognition of the markers; during the UAV's approach phase, it experiences trajectory deviation due to weak airflow disturbances, and the system monitors the attitude deviation in real time and quickly corrects it through a PID compensation algorithm; during the landing process, the ground environment monitoring module provides real-time feedback that the wind speed is normal and there is no external interference; the UAV accurately lands at the center point of the ground facility, completes electromagnetic locking after touchdown and buffering, and there is no deviation or overturning throughout the entire process, verifying the reliable landing capability of this invention in complex lighting and slight disturbance environments.

[0101] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A control method for a drone landing ground facility guidance and safe landing control device, characterized in that, Includes the following steps: Step 1: Pre-landing Status Verification and Target Lock-in: After the ground landing facility is activated, it uploads its own position, status, and landing authorization to the low-altitude control platform in real time, while continuously transmitting a dedicated guidance reference signal; after receiving the return landing command, the UAV first completes a self-check of its own power, sensors, and communication modules. If the self-check is successful, it locks onto the target ground landing facility through the low-altitude control platform, obtains the facility's precise coordinates and guidance signal frequency band, and completes the landing target lock-in; if the self-check is abnormal, the UAV immediately hovers and sends a fault alarm, terminating the landing process; Step 2, Remote Guidance During the Approach Phase: The drone flies over the target ground landing facility and, upon entering the approach area, switches to the ground facility's remote guidance mode. The ground landing facility sends real-time position correction data to the drone through its positioning enhancement module and wireless communication module. Combined with the drone's own RTK positioning, coarse positioning calibration is completed, the optimal approach and landing route is planned, and the drone is controlled to smoothly descend to the preset landing hovering altitude. During this phase, environmental monitoring is simultaneously activated to collect real-time data on wind speed, wind direction, and precipitation. If environmental parameters exceed the safe landing threshold, the drone is controlled to remain hovering and wait until the environmental conditions are met or the emergency landing procedure is initiated. Step 3, Precise Positioning Stage: Visual and Signal Fusion Guidance: After the UAV reaches the preset hovering height, it activates the onboard visual recognition module to capture the unique visual markers on the ground landing facilities, while simultaneously receiving high-precision short-range guidance signals transmitted by the ground facilities. A fusion positioning algorithm combining visual positioning and radio frequency guidance is adopted to calculate the relative position and attitude deviation between the UAV and the landing center point, eliminating single positioning interference data and achieving centimeter-level accurate positioning. During the positioning process, image quality is optimized in real time, and visual images in strong light and low light environments are equalized to ensure that positioning accuracy is not affected under complex lighting conditions. Step 4: Safety Monitoring and Attitude Correction Throughout the Landing Process: As the drone begins its vertical descent, ground facilities and the drone simultaneously initiate safety monitoring. The drone monitors its own flight attitude, altitude, descent rate, and power reserve in real time. Ground facilities use radar and visual sensors to monitor obstacles in the landing area and the drone's landing trajectory, simultaneously feeding back the monitoring data to the drone controller. Based on the real-time monitored position and attitude deviations, a PID control algorithm with compensation is used to dynamically adjust the drone's rotor speed and flight attitude, correcting the landing trajectory in real time to ensure that the drone always descends along the vertical line of the landing center, eliminating the risk of lateral deviation. Step 5, Ground Buffer and Landing Lock Control: When the UAV descends to a height close to the ground facility's touchdown height, it automatically reduces its descent rate and initiates soft landing buffer control to reduce the impact force upon touchdown. After the UAV touches down, the ground facility immediately triggers the landing lock mechanism, securing the UAV's landing gear through mechanical positioning or electromagnetic adsorption, while simultaneously cutting off the UAV's power. The ground facility simultaneously uploads a landing success signal, completing the entire landing process. Step Six: Emergency Safety Handling for Abnormal Situations: During the entire landing process, if the positioning signal is interrupted, the drone loses attitude control, obstacles appear in the landing area, power is insufficient, or there are sudden abnormal environmental changes, the system will immediately activate emergency control: If it is in the approach phase, control the drone to climb to a safe altitude and hover; if it is in the precision landing phase, control the drone to hover urgently and reposition; if a serious malfunction occurs, initiate the nearest safe emergency landing or low-altitude slow descent procedure to minimize equipment damage and safety accidents.

2. The control method of the UAV landing ground facility guidance and safe landing control device according to claim 1, characterized in that: The error state vector of the UAV in step two is defined as follows: ， Where, p k v represents the position of the drone relative to its take-off and landing point. k Let q be the relative velocity. k Let b be a quaternion of attitude. a,k and b ，k These are the accelerometer and gyroscope zero bias, respectively. k Here is the estimate of the lateral wind disturbance; the discrete propagation equation based on the IMU is written as:

3. Among them, u k This represents the measurement input of the IMU at time k. The sampling period provides high-frequency predictions of the propagation results, but these are not directly used as the basis for allowing a decrease. The UWB measurement model is as follows: ， in, Let i be the position of the i-th UWB anchor point in the take-off and landing point coordinate system. For systematic bias terms, For random noise, the visual reprojection model is: ， in, Here, K is the camera projection operator, and K is the intrinsic parameter matrix. Let m be the camera-relative takeoff and landing point transformation matrix derived from the airborne state. j Let be the homogeneous coordinates of the j-th visual marker in the take-off and landing coordinate system.

4. The control method of the UAV landing ground facility guidance and safe landing control device according to claim 1, characterized in that: The PID control algorithm with compensation term in step four is specifically as follows: Ground facility parameter package and synchronization interface: The parameter package output by the ground facility preferably includes: Take-off and landing point markings The parameters are the version number (ver), timestamp (t0), and valid window. UWB anchor set Visual marker geometric set safety zone boundary of take-off and landing point Stage speed limit Along with the attitude limit and the ground capability bitmap Ccap, it is used to declare whether wind field assistance, light assistance or backup guidance is supported. After receiving the parameter package, the UAV performs timestamp and version verification, and only loads the parameter package if it is within the valid time window; if the version changes, the coordinate system reset and anchor point geometry consistency verification are completed first before proceeding to the next step. Multimodal measurement acquisition and time alignment: The UAV acquires IMU, altitude, UWB and visual measurements respectively. Preferably, the IMU sampling frequency is 100Hz to 400Hz, the UWB update frequency is 20Hz to 100Hz, and the camera frame rate is 20fps to 60fps. Time synchronization adopts a combination of nearest neighbor interpolation and extrapolation to ensure that UWB and visual measurements are aligned with the IMU propagation timeline, avoiding mistaking old measurements for new measurements due to time misalignment during rapid descent. Error state fusion and modal adaptive update: In each fusion cycle, the system first performs IMU pre-integration propagation, then performs UWB update and visual update based on the measured data. If vision is temporarily unavailable, only UWB update is retained; if the whitening residual of UWB continues to increase, its update weight is reduced, and vision / IMU becomes the dominant factor. Preferably, the adaptive weight is written as: ， in, and These represent the normalized residual energy of UWB and visual modality, respectively; Phased integrity assessment and protected descent divide the landing process into four phases: approach phase, alignment phase, descent phase and touchdown phase, with each phase corresponding to different integrity thresholds and velocity constraints. Wind disturbance estimation and compensation: Lateral wind disturbance is estimated by combining changes in airframe speed, visual ground drift and UWB position residuals. When the wind disturbance amplitude continues to rise but has not yet triggered the go-around threshold, the controller first compensates through feedforward terms. If the wind disturbance causes the value to exceed the safety margin, the descent is paused and the aircraft waits for realignment or transfer to a backup take-off and landing point. The ground contact confirmation and emergency backup measures do not use a single ground contact switch for ground contact confirmation. Instead, they use a combination of altitude, vertical velocity, rate of change of attitude, and short-term vibration response for judgment. If the ground contact conditions are not met, but the altitude is already close to the ground, the landing will proceed with a slow descent hold. If both visual and UWB fail for more than a set time, the landing procedure will be terminated and the aircraft will go around.

5. The unmanned aerial vehicle (UAV) landing ground facility guidance and safe landing control device according to any one of claims 1-3, comprising a UAV fuselage (1) and a system, Its features are: The drone housing (1) has mounting bases (2) fixedly installed at both ends on both sides. Angle rods (3) are rotatably connected to one end of each of the four mounting bases (2). Motor bases (4) are fixedly installed at one end of each of the four angle rods (3). A flight propeller (6) is provided on one side of each of the four motor bases (4). The system includes ground landing facilities and a drone platform. The ground-side module is located on the ground facility side, and the airborne module is located on the drone side.

6. The UAV landing ground facility guidance and safe landing control device according to claim 4, characterized in that: The ground-based module includes a main control unit, a guidance signal transmission module, a visual identification module, an environmental monitoring module, an obstacle monitoring radar, a mechanical locking unit, a wireless communication unit, and a power management module. The main control unit is the core control component on the ground, responsible for coordinating the operation of various modules, analyzing UAV status data, issuing guidance commands, and controlling emergency protection actions. The guidance signal transmission module adopts a fusion transmission mode of radio frequency and positioning enhancement, providing coarse positioning guidance signals remotely and high-precision calibration signals at close range. The visual identification module uses high-contrast, strong light interference-resistant exclusive identification, combined with a supplementary lighting unit, to adapt to all-weather visual recognition. The environmental monitoring module collects wind speed, temperature, humidity, and precipitation environmental parameters in real time to determine the safety of the landing environment. The obstacle monitoring radar scans the landing area in real time to identify obstacle risks. The mechanical locking unit is used to quickly fix the drone's fuselage after it touches the ground to prevent slippage and overturning; the wireless communication unit enables three-way data interaction between ground facilities, drones, and low-altitude control platforms to ensure real-time signal transmission; the power management module provides stable power supply for the entire ground-end device and supports dual-mode switching between mains power and backup power.

7. The UAV landing ground facility guidance and safe landing control device according to claim 4, characterized in that: The airborne terminal module includes an airborne main control chip, a signal receiving module, an airborne vision sensor, an attitude monitoring unit, a data processing unit, an emergency control unit, and a communication module. The airborne main control chip is responsible for receiving ground guidance signals, parsing control commands, and outputting flight attitude adjustment commands; the signal receiving module is paired with the ground guidance signal transmitting module to receive guidance and positioning correction data in real time; the airborne visual sensor is used to capture ground visual markers and complete visual positioning calculations; the attitude monitoring unit collects UAV flight attitude, altitude, descent rate, and power margin data in real time; the data processing unit is equipped with a fusion positioning algorithm and attitude correction algorithm to quickly calculate position deviations and generate control parameters; the emergency control unit is used to trigger emergency hovering and emergency landing actions in abnormal situations; the communication module ensures real-time data interaction between the airborne end, the ground end, and the control platform, achieving full information synchronization.

8. The unmanned aerial vehicle (UAV) landing ground facility guidance and safe landing control device according to claim 4, characterized in that: Each of the four mounting bases (2) has a stepper motor (7) fixedly mounted on its bottom end, and the output end of each of the four stepper motors (7) is fixedly connected to the side of the angle rod (3) directly opposite to it.

9. The unmanned aerial vehicle (UAV) landing ground facility guidance and safe landing control device according to claim 4, characterized in that: A servo motor (5) is fixedly installed on one side of each of the four motor bases (4), and the output ends of the four servo motors (5) are fixedly connected to the opposite ends of the four propellers (6).

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