Hoisting construction method based on unmanned aerial vehicle

Abstract

The invention discloses a hoisting construction method based on an unmanned aerial vehicle. According to the method, on the basis of a digital model of a construction site and a to-be-installed component, a load and a cooperative time sequence are distributed for a single unmanned aerial vehicle or multiple unmanned aerial vehicles, then a safety channel from a hoisting point to an installation point is generated in the model, and a dynamic geofence capable of being automatically updated along with factors such as a wind field, temporary obstacles and personnel entry is established; the method is used for constraining route and approach strategies. In the transportation process, the system adjusts the attitude of the unmanned aerial vehicle and the tension of the sling in the flight process according to the swing state of the component and feedback of the tension of the sling to suppress swing of the component. When the component is conveyed to a near field, high-precision positioning is switched, butt joint and fixation are achieved through a self-alignment connector with guiding and maintaining functions, and unloading and unhooking are conducted in sequence. Flight, stress, attitude and environment data are recorded in the whole operation process and written back to the building information model or the digital twin for acceptance and tracing; and when strong wind, abnormal communication or single machine fault occurs, emergency strategies such as speed reduction, weight redistribution, controlled descending, homeward voyage or quick release are executed. The method has advantages in areas where vehicles are difficult to enter or roads are not suitable for being repaired, such as updated cities, mountainous regions and scenic spots, and scenes where rapid deployment is needed and ecological protection is emphasized, such as border plateaus; an unmanned aerial vehicle integrated courier station can be arranged on site to provide task scheduling, energy charging supply, communication relay and positioning reference support so as to improve the continuous operation capability.

Description

Technical Field

[0001] This invention relates to the fields of intelligent construction and drone applications, particularly a method for aerial hoisting and alignment installation of building and infrastructure components using single or multiple drones. The method encompasses processes such as digital modeling of the construction site and components, task allocation and collaborative control, generation of three-dimensional safety passages and dynamic geofences, closed-loop control of swaying and stress during transportation, near-field high-precision alignment and self-alignment interface installation, as well as data write-back and emergency response. Background Technology

[0002] In engineering practice, traditional component hoisting mainly relies on tower cranes, truck cranes, or cable systems. These devices typically require pre-deployment and commissioning, occupy large areas of space, incur high relocation costs, and are significantly limited by road access and hoisting radius. In mountainous areas, canyons, scenic spots, or areas with dense water networks, temporary roads and platforms often need to be constructed, resulting in long construction periods, significant disruption, and, in ecologically sensitive areas, facing approval and environmental pressures. For temporary or small-batch installation tasks, the mobility and reusability of traditional equipment are insufficient, and ground-based manual assistance methods are easily limited in terms of safety and efficiency. These objective obstacles have prompted the industry to seek new construction methods centered on drones that offer "less road construction, less disruption, and rapid deployment."

[0003] Publicly available technologies have attempted to utilize drones for lifting or assisted lifting from different perspectives, but most remain focused on a single stage. For example, CN113359427A proposes a multi-drone collaborative lifting and "positioning and sway reduction" control scheme. By collecting system status data and designing a nonlinear controller to suppress load sway, the core lies in the control effect of "flight + sway reduction," emphasizing transportation stability rather than the complete closed loop of the installation process. CN103699130A increases the number of booms and drones through a "multi-drone coordinated flying crane device," focusing on load-bearing and balance adjustment at the device and mechanism level. CN205169496U, on the other hand, is geared towards an "item lifting and placement system" for aerial logistics, emphasizing the safety of landing and emergency release, with the primary scenario being delivery rather than engineering installation. On the other hand, there is also research on "dynamic fencing" in airspace operation safety: CN112116830A gives a "dynamic geofencing planning method for UAVs" based on low-altitude airspace gridding, which is used to dynamically generate fences according to airspace complexity and planned flight paths; CN107533331A involves "geofencing equipment" with dynamic characteristics, which can issue boundary conditions to UAVs to restrict flight areas; there are also schemes such as CN115906579A that use UAVs to conduct status assessment and monitoring of the hoisting process of large-span steel structures, emphasizing monitoring and digital twin verification. The aforementioned technologies have made valuable explorations in areas such as collaborative sway control, device support structure, hoisting and release, airspace fencing and operation management, and construction monitoring. However, they are still "single-point improvements" in general. They either stop at the level of transportation and sway suppression, focus on the device itself, or focus on airspace safety or monitoring and assessment. They have not integrated "site model - path and fencing - transportation closed loop - near-field alignment - standardized interface locking - data write-back - anomaly handling" into a chain of construction methods that can be directly implemented. In particular, in complex terrain and ecologically sensitive scenarios, there is a lack of a reusable, reviewable, and implementable construction method system.

[0004] Based on this gap, this invention proposes a drone hoisting construction method for installation conditions: using the digital model of the site and components as a unified benchmark, load coordination and task allocation are first carried out; on this basis, a three-dimensional safety channel is generated and a dynamic geofence that can be automatically updated according to changes in wind field, personnel, and temporary obstacles is established, so that the safety boundary of "flyable, approachable, and fast" directly enters the path and speed control; during the transportation stage, swing-force-speed are incorporated into the same closed loop, and if necessary, the winch can be lengthened to avoid resonance and slow down the release; after reaching the near field, high-precision positioning and self-alignment interface (the functional combination of alignment unit and holding unit, which can be passive or active) are used to achieve fast, fault-tolerant automatic docking and locking, and unloading is carried out in sequence to maintain attitude stability; the entire process data is written back to BIM and digital twin to support acceptance and traceability; in the scenario with anchor points, an external winch can be selected to bear at least part of the vertical force or slow down the release, and the drone focuses on attitude and alignment; when continuous operation is required, an integrated drone station can be configured on site to provide scheduling, charging, communication relay and positioning benchmark support. Compared with the aforementioned publicly available routes, this invention is not an improvement on a single module, but rather a complete construction method that connects "dynamic fence - path - transportation closed loop - near-field alignment - standardized interface - data closed loop - abnormal state machine" into an implementable, reusable, and auditable method with the method as its core. It solves the bottleneck of traditional hoisting in terms of road dependence and environmental disturbance, and also fills the gaps in the existing patents' separation of transportation, equipment, control and monitoring. Therefore, it has novelty and significant comprehensive technical effects. Summary of the Invention

[0005] Purpose of the invention:

[0006] This invention aims to propose a drone-based hoisting construction method. It uses a digital model of the construction site and components as a unified benchmark, linking task allocation and coordination, three-dimensional safety passages and dynamic geofencing, closed-loop control of swaying and stress during transportation, near-field high-precision alignment and self-alignment interface locking, and data write-back and anomaly handling into an executable construction chain. This method solves the problems of traditional hoisting methods, such as heavy reliance on roads and large equipment, difficulties in organizing operations in mountainous and scenic areas, and significant disturbances. It enables reliable installation with minimal or no road construction in environments requiring rapid deployment, such as border regions and plateaus.

[0007] This invention further aims to improve the accuracy, stability, and repeatability of installation while ensuring safety: swing / force feedback drive control is used during transportation; upon approaching the installation area, rapid locking is achieved through near-field positioning and an interface with fault-tolerant guidance and holding functions, and the operation data is written back to BIM / digital twin for acceptance and traceability. Depending on the needs, the method can collaborate with an external winch to complete slow lowering or share vertical force, and an integrated drone station can be configured on-site to provide scheduling, power replenishment, communication, and positioning reference support, thus forming a reusable, auditable, and implementable drone hoisting construction solution.

[0008] Technical solution: To achieve the above objectives, the present invention adopts the following technical solution.

[0009] This invention uses a digital model of the construction site and the components to be installed as a unified benchmark. First, it integrates layers such as Building Information Modeling (BIM), on-site survey point cloud image reconstruction, terrain and obstacles, no-fly zones, personnel activity areas, temporary facilities, and wind environment, all under the same coordinate and time benchmark. Simultaneously, it marks the target installation location and attitude, permissible access areas, and safety boundaries. This model serves as the sole data source for subsequent task allocation, access / fence generation, near-field alignment, and data write-back, avoiding error propagation caused by inconsistencies between multiple sources. If necessary, positioning benchmarks or visual markers are deployed on-site as reference points for the near-field phase. For construction sites requiring continuous operation, integrated UAV stations can be configured as needed to provide task scheduling, power replenishment, communication relay, and positioning benchmark services. The stations serve only as implementation support and are not limited to any specific structure.

[0010] In terms of operation organization, roles and load shares are assigned to single or multiple UAVs based on component mass, external dimensions, lifting point layout, and center of gravity estimation, forming a collaborative relationship between the master, slave, follower, and escort UAVs. The traction responsibilities and following objects are clearly defined, and communication and timing synchronization strategies are established. When multiple UAVs collaborate, the load sharing relationship can be calculated based on the component lifting point geometry and aircraft capabilities, allowing for fine-tuning during the transportation phase based on force and sway feedback. For small parts or tasks with limited space, a single UAV can be used while maintaining the same modeling-planning-alignment process. For heavy parts or tasks requiring more stable vertical force, external winches on the ground, bridge deck, or platform can be introduced to bear at least part of the vertical force or provide a gentler release, allowing the UAV to focus on attitude and position fine-tuning. Both work together to complete alignment and locking.

[0011] Subsequently, a three-dimensional safety passage is generated in the digital model from the lifting point to the installation point, and a dynamic geofence is established that can be automatically updated according to the environment and construction status. The safety passage matches the outline of the component, taking into account minimum clearance, minimum height, turning characteristics, and permissible speed. Examples can be given in the instruction manual: the horizontal and vertical safety margins of the passage can be set according to a certain proportion of the maximum outline of the component (e.g., 20% or according to the fixed minimum clearance given by the site), the minimum flight altitude can be higher than the highest obstacle along the route by a safety margin (e.g., several meters), and the turns adopt a smooth transition to reduce the inertial impact of the suspended component. The dynamic geofence shrinks or expands according to wind field estimation, temporary obstacles, personnel approach, or work procedure changes, and transmits speed limit, height limit, and approach strategies as boundary conditions to flight and lowering control; once the fence is triggered or tightened to within the threshold, it can be used as one of the triggering conditions for abnormal handling.

[0012] The lifting and transportation phases are executed in a closed-loop manner, following a "state-control-constraint" model. After the UAV completes the attachment and lifting, it flies along a safe passage. The controller continuously collects data on the component's swaying state, sling stress, aircraft attitude, and relative position. Combined with task allocation results and geofence boundaries, it adjusts thrust, attitude, and speed to suppress and balance swaying and stress. In scenarios with winches or variable-length slings, the sling length can be changed to adjust the equivalent sway characteristics, avoiding resonance and enabling gentle release near the ground or installation location. In scenarios without winches, the goal can be achieved through refined speed and attitude control. In multi-UAV collaboration, the master unit publishes a reference trajectory and relative pose, while slave units follow and share the load using tension and relative pose feedback. When communication quality deteriorates or a particular unit's performance declines, the collaboration strategy can degenerate into a locally autonomous slave-master coupling to ensure basic controllability. For ease of reproduction and debugging, the manual provides optional example objectives: during transportation, the goal is to keep the component's swaying within allowable limits and the sling stress fluctuations within safe limits.

[0013] Before entering the near field, the system determines whether the position, speed, and sway meet the proximity conditions based on preset thresholds, and then switches to near-field positioning mode. Near-field positioning can employ satellite augmentation, UAV vision (marked or natural features), ultra-wideband, laser ranging, or a combination thereof, depending on environmental conditions, and allows for smooth switching between near and far fields. Approaching and lowering utilize low-speed micro-movements and small-step adjustments, combined with minor lateral and vertical corrections, to ensure that the component remains within a controllable range when approaching the installation location. To improve alignment success rate and repeatability, the installation end adopts a self-alignment interface, which consists of an alignment unit and a holding unit. The alignment unit guides the component to automatically center and eliminate misalignment when there are initial position and attitude deviations. It can be selected from one or more of the following: conical surface, flared mouth, V-groove, boss and concave seat, roller guide, magnetic guide or compliant guide. The holding unit maintains connection stability after alignment. It can be selected from one or more of the following: wedge pin, snap fastener, cam, thread, snap ring, magnetic attraction limit, electromagnetic or pneumatic clamping. It can be passive or include active implementation by a small stroke actuator.

[0014] After locking is completed, sequential unloading is performed: the maintaining drone can maintain attitude stability, while the other drones gradually unload and detach according to a preset sequence, smoothly transferring the load from the drone system to the structural body or temporary support; in scenarios using external winches, the winch can first stabilize the load, and then the drones can detach sequentially to reduce disturbance to the component's attitude. During the mission's final stage, the escort aircraft / monitoring unit collects images and measurement data on the completed installation status, using fixed stations or component-end sensors to obtain the actual installation position, connection status, and tightness for quality acceptance.

[0015] Data management is integrated throughout the entire operation. The system records information such as flight trajectory, attitude, forces, wind environment, events, and installation position, forming a time-series operation log. Data is aggregated locally and at the backend as needed, and written back to the building information model or digital twin to update component status, actual installation deviations, and quality acceptance records, providing a basis for subsequent procedures and experience reuse. Data signing and retention can be performed when necessary to meet traceability and compliance requirements.

[0016] Safety and anomaly handling are managed uniformly using a state machine approach, linked with dynamic geofencing: when there are sudden changes in wind field, communication anomalies, reduced single-unit capacity, or when a geofence is triggered, one or more of the following strategies are executed according to preset rules: deceleration, weight redistribution, path replanning, controlled descent, return to base, or rapid release in a designated safe area; in winch-coordinated scenarios, in case of anomalies, the main vertical force can be transferred to the winch and controlled descent can be implemented. The process allows for suspension, rollback, or resumption, ensuring a clear handling path and a "safe landing point" at any stage.

[0017] The above steps can be performed sequentially, or in parallel or iteratively depending on the on-site organization; positioning methods, alignment and holding structures, hoisting coordination strategies, unloading sequences, and data organization can be selected or replaced as needed. As long as the overall requirements of using a digital model as a benchmark, dynamic fences and safety passages as constraints, swing-force-velocity joint feedback as the core, self-alignment interface for locking, data write-back to form a closed loop, and clear abnormal handling paths are met, all are considered equivalent implementations of the present invention.

[0018] Beneficial effects:

[0019] Compared with existing technologies, the drone-based hoisting construction method of the present invention has significant beneficial effects.

[0020] This invention generates safe passages based on a unified on-site digital model and introduces a geofence that can be dynamically updated according to wind field, personnel, and temporary obstacles. This transforms boundaries such as "whether it can fly, when to approach, and at what speed" into executable control conditions from the design stage. When the geofence tightens or is triggered, the process automatically switches to deceleration, path replanning, or controlled descent. This "pre-emptive safety constraints → automatic handling" approach is consistent with the governance concept of the European "U-space Unmanned Aerial Vehicle (UAV) Integrated Service System," which can significantly reduce airspace conflicts and near-field instability risks in complex construction sites.

[0021] During the transportation phase, the method treats load sway, force, and velocity as a single control object, employing combined attitude and velocity feedback to suppress sway. When conditions permit, flexible release and avoidance of resonance can be achieved by changing the sling length, thereby reducing sway amplitude and peak impact. Related lifting and hoisting studies have repeatedly demonstrated that anti-sway strategies based on input shaping and feedback can significantly reduce residual sway. This method solidifies these proven mechanisms into reusable process controls, facilitating the repeated achievement of stable results in different locations.

[0022] Upon approaching the installation area, positioning and alignment transition from "accessible" to "accurate." Depending on environmental conditions, Real-Time Dynamic Differential Satellite Positioning (RTK), visual positioning, and Ultra-Wideband (UWB) positioning can be combined and switched: with a view of the sky and support from a base station, RTK can achieve centimeter-level relative positioning accuracy; in areas with obstructions or numerous metal components, UWB can maintain dynamic accuracy of approximately ten centimeters even in non-line-of-sight situations. Combined with a self-aligning interface featuring fault-tolerant guidance and holding functions, and sequential unloading after locking, the number of repeated approaches and manual alignment can be reduced, improving the first-time docking success rate and installation consistency.

[0023] This invention records and writes back process data such as "flight-force-attitude-environment-installation position and attitude" to "Building Information Model (BIM)" or digital twin for quality acceptance, deviation verification and debriefing optimization. As the number of task batches increases, the safety passage and fence parameters in the model can be iterated accordingly, forming a "the more you do it, the more stable it becomes" learning curve, shortening the organization and debugging time, and supporting continuous operation.

[0024] In scenarios with anchor points or requiring more stable vertical force, an external winch can be introduced as needed to share the vertical force or handle the slow descent, allowing the UAV to focus on attitude and position fine-tuning. In the event of sudden winds or a decrease in the capabilities of individual aircraft, the vertical force can be quickly transferred to the winch for controlled descent. Engineering and simulation studies have fully validated the effectiveness of "changing cable length / using winch slow descent to reduce sway and impact," thus demonstrating higher resilience under extreme conditions.

[0025] Compared to the traditional approach of "building roads and using large lifting equipment," this method can directly lift components from accessible points to the installation location, reducing the need for temporary roads and large platforms, shortening the preparation period, and minimizing disturbance to the ecological environment. Authoritative assessments and studies have long indicated that road construction and transportation cause habitat fragmentation, restricted species movement, and hydrological changes. Furthermore, this method transforms "positioning at height" into "aerial alignment, automatic locking, and sequential unloading," directly reducing exposure to heights. The latest occupational injury statistics show that in 2023, "falls, slips, and trips" accounted for nearly 40% of fatal accidents in the construction industry. Controlling the duration of work at heights offers clear safety benefits and aligns with the industry's recent focus on controlling the risk of falls from heights. Attached Figure Description Figure 1 This is a schematic diagram of the operation process for a drone-based hoisting construction method. Figure 2 This is a flowchart of the control state machine for the hoisting construction method. Detailed Implementation

[0026] Example 1: Scenario of aerial docking and installation of prefabricated modular buildings

[0027] The urban renewal project in the central city has a minimum working area of ​​approximately 12 meters, adjacent to a sidewalk and crossing a 10kV overhead power line, making it impossible to install a tower crane. The project requires the precise hoisting of a complete module, approximately 6m × 3m × 2.8m in size and weighing about 10 tons, to the 5th-floor foundation within a 4-hour nighttime window, with common crosswinds ≤ 6m / s. Before commencement, a unified coordinate and time baseline was established through laser scanning and BIM integration, generating a digital task package of obstacles, no-fly zones, and target poses. This ensures that subsequent paths and control boundaries have verifiable data sources, reducing on-site uncertainties and shortening the lockdown time.

[0028] This method employs a multi-machine collaborative and load-sharing aerial hoisting architecture: the central machine provides steady-state amplitude limiting, the four corner machines share the main load, and group control consistency is achieved through bus clock synchronization and attitude / tension closed-loop. The module features a prefabricated guide cone insertion-locking integrated self-aligning interface, and the platform is equipped with a matching base, providing passive correction capability from a structural level, improving the success rate of first-time seating and locking, and reducing disturbances and noise caused by repeated alignment.

[0029] During the task planning phase, a three-dimensional safety passageway is generated based on BIM, consisting of a "stacking area - corridor - installation area," with lateral and vertical margins extended by 2-3 meters according to the component outlines. Dynamic geofencing is set up around the pedestrian passageway and the 10kV line, updating speed limits, height limits, and approach strategies in real time according to changes in pedestrian flow and wind field. This pre-emptively controls "whether it can fly, how to approach, and speed boundaries," reducing near-instability and collision risks from the source and avoiding large-scale road closures.

[0030] Each machine is equipped with a winch with variable length mechanism (step distance ≤10mm) and a 50–100 Hz tension / attitude sensor. The transport cruising speed is 2.5-3.0m / s, and the control swing angle |θ|≤3° and tension deviation at each lifting point ≤±8%. Once the limit is exceeded, a linkage of "deceleration-attitude differential-winch ΔL fine adjustment" is triggered to suppress the swing, balancing efficiency and stability, and reducing energy consumption and noise exposure caused by mid-journey hovering.

[0031] Upon entering the near field, the system switches to combined positioning (satellite augmentation / visual / UWB smooth relay), approaching to approximately 1.0m above the target location at a speed of 0.3-0.5m / s, and then simultaneously lowering at a speed of 0.05-0.10m / s. The guide plug's placement is confirmed by the stroke or contact pressure threshold. Subsequently, a sequential strategy of "holding the machine first to stabilize the load—releasing the hooks of the others in sequence—holding the machine last to unload" is followed to complete the force transition, with real-time correction of the levelness to ≤0.2°. This ensures the continuity of force between the components and the base, suppressing impact and secondary swaying, thereby achieving millimeter-level positioning and low-disruption operation.

[0032] After the operation is completed, the flight trajectory, load time history, attitude, and positioning deviation are automatically written back to the BIM, forming traceable acceptance and review data for subsequent batch parameter adaptive optimization, making the batch installation cycle more stable. In case of gusts, communication failures, or degraded single-unit performance, the system will execute deceleration, weight redistribution, controlled descent, or return to base according to preset strategies, ensuring mission safety while reducing downtime. If anchor points are available on site, ground winches can be added to share some of the vertical force to further reduce sway amplitude; when continuous operation is required, an integrated UAV station can be configured to provide recharging and local high-precision positioning reference, improving turnaround efficiency and night window utilization.

[0033] The benefits of using this patented method in this scenario are as follows: No tower cranes or large-scale road closures are required; the three-dimensional safety passage and dynamic geofencing pre-determine the control conditions of "whether it can fly, how to approach, and speed boundaries," significantly reducing the risk of near-instability with pedestrian walkways and 10kV lines; the combined feedback of swing-force-speed and winch fine-tuning reduces repeated alignment and secondary entry; the self-alignment interface and sequential unloading improve the success rate of first-time locking and installation consistency; and the write-back of work data supports acceptance and traceability, and accelerates parameter optimization of subsequent modules, achieving high-quality installation in the central urban area with "minimal land occupation, low disturbance to residents, and millimeter-level positioning."

[0034] Example 2: High-rise curtain wall panel installation without tower crane in the air

[0035] A renovation project of a 24-story office building faced limitations due to setbacks and traffic flow restrictions, preventing the installation of tower cranes. The narrowest point of the internal street between the podium and the main building was approximately 8 meters, allowing only nighttime construction between 10:00 PM and 2:00 AM. Unitized curtain wall installation was required on the east facade, with each unit panel measuring approximately 2.6m × 1.3m × 0.18m and weighing 0.9-1.1 tons. Balconies, billboards, and localized air conditioning unit locations were present around the facade, along with pedestrian walkways and municipal green spaces. Crosswinds were typically ≤6 m / s, and wind ducts and recirculation zones existed near the facade. Before commencement, laser scanning and BIM overlay were used to establish a unified coordinate and time baseline, generating an integrated model of the facade, obstacles, and ancillary facilities. This model clearly defined the target installation positions, allowable errors, and work time windows, providing verifiable data for subsequent paths, speeds, and safety boundaries, thus reducing temporary closures and on-site uncertainties from the outset.

[0036] This method employs a multi-machine collaborative aerial hoisting architecture: four collaborative multi-rotor drones are used, each with a rated load of ≥300kg. The four-point hoisting is distributed approximately 30%, 30%, 20%, and 20%, with adaptive fine-tuning based on center of gravity shifts. Central control ensures group control consistency through bus clock synchronization and attitude / tension closed-loop control. The back of the curtain wall unit panels is pre-installed with a "guide cone insert + electric drive lock integrated interface," and the columns are equipped with matching sockets and limit tracks. This provides passive correction and accommodates minor attitude differences at the connection structure level, improving the success rate of first-time placement and locking, and reducing disturbances and noise caused by repeated alignment.

[0037] During the mission planning phase, a 3D safety corridor is generated based on BIM, consisting of "ground storage yard - vertical window - target floor": horizontally, the width of the platform is extended outward by 2-3m, and vertically, the height of the platform is extended outward by approximately 2m. Dynamic geofences and phased time window controls are set up around pedestrian walkways, balconies, and along the route, automatically updating according to changes in pedestrian flow and wind field. "Whether it can fly, how to approach, and speed and height boundaries" are pre-defined as control conditions, avoiding large-scale road closures and significantly reducing near-instability and collision risks. Each machine is equipped with a winch length-adjusting mechanism (step distance ≤10mm) and a 50-100Hz tension / attitude sensor. The transport cruising speed is 2.0-2.5m / s, decreasing to 0.6-0.8m / s upon entering the facade air duct. Process control aims for a swing angle |θ|≤3° and tension deviation at each lifting point ≤±8%. Exceeding these limits triggers a coordinated "deceleration—attitude differential—winch ΔL fine-tuning" mechanism to suppress the swing, balancing efficiency and stability while reducing energy consumption and noise exposure caused by mid-journey hovering.

[0038] Upon entering the near field, the system switches to high-precision combined positioning (satellite augmentation, vision, and UWB smooth relay). At approximately 0.8-1.0m above the support, it is simultaneously lowered at a speed of 0.05-0.10m / s. When the insertion depth or contact pressure reaches the threshold, the electric lock engages and provides feedback. Sequential unloading follows a strategy of "retaining two units under stable load—releasing the hooks of the other two units—unloading the holding unit last" to complete the force transition. The levelness is corrected in real-time to ≤0.2°, and the seam error is controlled to approximately ±6-8mm. Through a "holding unit first, unloading in stages, and final verification" chain, impact and secondary sway are suppressed, achieving millimeter-level positioning and low-disruption operation on high-rise facades.

[0039] After the operation is completed, the flight trajectory, load time history, attitude, and positioning deviation are automatically written back to the BIM, forming traceable acceptance and review data for subsequent zoning parameter adaptive optimization, enabling batch installations to achieve consistent accuracy and cycle time more quickly. In the event of gusts, communication anomalies, or a decline in individual drone performance, the system will perform deceleration, load redistribution, controlled descent, or return to base according to preset thresholds, reducing downtime and ensuring operational safety in adjacent areas of the facade. If the roof of the podium or parapet wall can provide anchor points, an external winch can be optionally installed to share some of the vertical load, allowing the drone to focus on attitude and position fine-tuning to further reduce sway and impact. For continuous nighttime operations, an integrated drone station can be configured to provide scheduling, recharging, and local high-precision positioning references, improving single-night processing capacity and turnaround efficiency.

[0040] Through the aforementioned organization, the original challenge of "high-altitude positioning" has been transformed into a closed-loop process of "aerial alignment, automatic locking, and sequential unloading," enabling the installation of high-rise curtain walls without occupying the tower crane's slewing radius or closing large areas of roads. Three-dimensional safety corridors and dynamic geofencing reduce the near-instability risk of pedestrian walkways and facade facilities; winch fine-tuning and tension-attitude-speed joint feedback reduce repeated site visits; self-alignment interfaces and sequential unloading improve the success rate of locking on the first attempt and installation consistency; data write-back supports quality traceability and rapid parameter convergence, achieving high-quality installation of high-rise curtain walls with "minimal land occupation, low disturbance to residents, and millimeter-level positioning."

[0041] Example 3: Aerial Assembly Scenario of Large-Span Steel Structure Nodes

[0042] The roof renovation project of a stadium involves a main truss span of approximately 120m. The inner stands and cable net structure occupy the hoisting access, making it impossible to accommodate tower cranes and large crawler cranes. Only nighttime work windows from 23:00 to 03:00 are permitted. A box-shaped closure node (approximately 5.5m × 2.2m × 1.6m, weighing approximately 6-7 tons, with pre-drilled holes for M36-M42 high-strength bolts and dovetail guide grooves) needs to be installed at the intersection of the north arch truss and the longitudinal secondary truss. The surrounding area has curved purlins and lighting trusses, resulting in significant local airflow backflow. Before commencement, laser scanning and BIM overlay were used to establish a unified coordinate and time reference, forming a 3D channel model of "ground assembly area—stand gaps—roof skylights—node work positions." This model clearly defines obstacles, target positions, and allowable deviations, pre-setting path, speed, and clearance as control conditions to reduce temporary closures and on-site uncertainties.

[0043] This method employs multi-machine collaborative hoisting: Six collaborative multi-rotor cranes (each with a rated load ≥ 1.5t) are configured, with the four main cranes at the corners each carrying approximately 22%, 22%, 18%, and 18% of the load respectively, and two auxiliary cranes each carrying 10% and responsible for yaw and roll limiting. Bus clock synchronization combined with attitude / tension closed-loop control ensures consistent group control. The nodes are equipped with a self-aligning interface integrating a conical sleeve, guide pin, and wedge lock. Existing truss positions have pre-set adjustable support saddles and limiting grooves, providing passive correction and accommodating minor attitude differences at the connection structure level, improving the success rate of first-time seating and locking, and avoiding disturbances and noise caused by repeated alignment.

[0044] During the mission planning phase, a safety corridor is generated based on BIM: the lateral margin is extended by 2-3m outwards from the node outline, and the vertical margin is extended by 2-3m outwards. Dynamic geofencing and phased time window control are set around the grandstand entrances / exits, cable nets, and lighting trusses, automatically updating according to changes in pedestrian flow and wind conditions. This provides data-driven basis for "whether it can fly, how to approach, and speed and height boundaries," avoiding large-scale scaffolding and site closures. Each machine is equipped with a winch with a variable-length mechanism (step distance ≤10mm) and a 50-100Hz tension / attitude sensor. The transport cruising speed is 2.0-2.5m / s, decreasing to 0.5-0.8m / s when entering the roof duct. Process control aims for a swing angle |θ|≤3° and a tension deviation of ≤±8% at each lifting point. Exceeding these limits triggers a coordinated "deceleration, attitude differential, and winch ΔL fine-tuning" mechanism to suppress swaying, balancing throughput efficiency and structural stability.

[0045] Upon entering the near field, a high-precision combined positioning system (satellite augmentation, vision, and UWB smooth relay) is switched. At approximately 1.0m above the workstation, a synchronous slow release at 0.05-0.08m / s is initiated. The conical sleeve is seated, the guide pin is inserted, and the fit is confirmed by the stroke / fitting pressure threshold. The wedge automatically locks and transmits a positioning signal. Subsequently, a sequential strategy of "maintaining stable load on two machines—releasing the remaining hooks in stages—and finally unloading the holding machine" is followed to complete the force transition. Simultaneously, the levelness is corrected in real-time to ≤0.2°, and the hole alignment error is controlled within ±6-8mm. The "maintaining stability first, unloading in stages, and final verification" link suppresses impact and secondary sway, reducing additional disturbance to the existing truss and cable net. For high-strength bolts requiring temporary fixation, a tethered electric wrench or platform robot is used to complete temporary tightening and torque verification, forming a rapid closed loop of "aerial alignment, mechanical self-locking, and temporary tightening consolidation."

[0046] After the operation is completed, the flight trajectory, load time history, attitude, and positioning deviation are automatically written back to the BIM, forming traceable acceptance and review data. This data is then used for adaptive optimization of parameters at subsequent symmetrical nodes, making the batch assembly cycle more stable and the accuracy more consistent. In the event of gusts, communication anomalies, or a decline in individual drone performance, the system will perform deceleration, load redistribution, controlled descent, or return to base according to preset thresholds, reducing downtime and ensuring the safety of the area adjacent to the roof. When the roof or truss end can provide anchor points, an external winch can be optionally installed to share part of the vertical load, allowing the drone to be used primarily for attitude and position fine-tuning, further reducing sway and impact. When continuous night shifts are required, an integrated drone station can be configured to provide scheduling, recharging, and local high-precision positioning references, improving the single-night processing capacity and turnaround efficiency.

[0047] Through the aforementioned organization, the assembly node operation, which originally required large hoisting equipment and extensive scaffolding, was transformed into a closed-loop process of "multi-machine collaboration, safe corridors, self-alignment locking, and sequential unloading." This allowed for high-altitude assembly to be completed without occupying the hoisting slewing radius or increasing the temporary load on the roof. Dynamic geofencing reduced the near-instability risk of the grandstand passageway and cable net. Tension-attitude-speed joint feedback and winch fine-tuning reduced repeated site visits. Data write-back supported quality traceability and rapid parameter convergence, achieving high-quality installation of large-span steel structure nodes with "less site closure, lower disturbance, and millimeter-level positioning."

[0048] Example 4: Erection Scheme for Prefabricated Building Floor Slab Components

[0049] Three 18-story prefabricated residential buildings (A, B, and C) were constructed simultaneously on the same residential plot. Only two 4-meter temporary passageways and a material storage area were available on site. The number of tower cranes was insufficient, and their turning range conflicted with that of an adjacent school. The standard floor slabs were reinforced concrete composite slabs, approximately 6.0m × 3.0m × 0.12m in size, with a single slab weighing 1.6-1.9t. Positioning holes and foundation clamps were pre-drilled along the edges of the slabs. To achieve the goal of "parallel rapid hoisting with low noise and minimal disturbance," the multi-UAV collaborative hoisting method of this patent was used for floor slab installation: each building was equipped with one group (each UAV had a rated load ≥250-300kg) of eight UAVs, with the three groups operating in parallel within the same night window.

[0050] Before construction began, three independent 3D safety corridors were generated using laser scanning and BIM fusion: the lateral margin was taken as the slab width + 2-3m, and the vertical margin as the slab height + 2m. Dynamic geofencing and time window control were set up around the school perimeter wall, temporary cables, and pedestrian walkways, automatically updating "flyability, approach methods, and speed / height boundaries" according to changes in pedestrian flow and wind field. The crane fleet was equipped with a winch length-adjusting mechanism (step distance ≤ 10mm) and tension / attitude sensors (50-100Hz), with a control bus delay ≤ 100ms. The lifting and cruising speed was 2.0-2.5m / s, with the target control being a swing angle |θ| ≤ 3° and tension deviation at each lifting point ≤ ±8%. If the limits were exceeded, the group control would trigger a coordinated "deceleration-attitude differential-winch ΔL fine-tuning" to suppress the sway, reducing the speed to 0.3-0.5m / s after reaching the installation area.

[0051] Attitude and Alignment Control: Each floor slab is equipped with 8 lifting points and a self-aligning interface on the back of the slab ("guide cone insertion + mechanical locking integration"). The ground support platform is equipped with a support saddle and a limiting slide groove. Near-field positioning adopts a combined positioning method (satellite enhancement, vision, UWB smooth relay). At about 0.8-1.0m above the support, the synchronous slow release is changed at 0.05-0.10m / s. When the cone insertion guide enters the socket and is confirmed to be in place by the stroke / fitting pressure threshold, mechanical locking is performed. The system monitors the horizontal and vertical tilt angles of the floor slab surface in real time. If the tilt angle in any direction is 0.2-0.3°, the opposite side and adjacent lifting points are coordinated to scale ΔL (single time ≤ ±50mm) until the levelness is ≤ 0.2°. Then, the hooks are released and positioned according to the sequential strategy of "keeping two machines under stable load - releasing the hooks in the rest of the order - unloading the hooks last". The splicing error is controlled within ±6-8mm.

[0052] Task organization and emergency response: The three drone groups are centrally controlled and simultaneously execute independent routes for buildings A, B, and C. When gusts of wind reach ≥8 m / s or the tension at any lifting point deviates by ≥±12%, the drone groups are moved to a safety buffer zone and reset to standby according to the pre-planned schedule. The transportation, placement, and locking of a single floor slab takes approximately 30 minutes. After installation, the flight trajectory, load time history, attitude, and placement deviation are automatically written back to the BIM database for parameter adaptation and quality traceability across building batches. When continuous night-shift operations are required, an integrated drone station can be activated for rapid refueling and health monitoring to maintain drone turnover.

[0053] This solution closely corresponds to the claims of this patent, resulting in significant effects: enabling the installation of three parallel, millimeter-level floor slabs without the need for tower cranes or large-scale road closures; reducing the cycle time for a single slab from approximately 60 minutes to approximately 30 minutes; improving the floor slab levelness from ±0.8° (manually corrected) to ≤±0.2°; reducing on-site personnel exposure and noise duration; increasing equipment turnover efficiency by approximately 100%; and achieving high-quality hoisting of prefabricated buildings that are "small in footprint, low in disturbance to residents, and replicable".

[0054] Example 5: Scenario of aerial hoisting of steel components for maintenance of in-service bridges without interrupting traffic.

[0055] A three-section continuous steel box girder bridge spanning the river requires the addition of support arms and triangular stiffeners at the bottom diaphragms to improve fatigue life. The bridge deck is a two-way six-lane road, with daytime traffic saturation and bridge closure not permitted; at night, only the emergency lane can be used for take-off, landing, and temporary maintenance. The waterway beneath the bridge is a Class IV waterway, requiring guaranteed navigational clearance and markers. The target component has an outer dimension of approximately 1.6m × 1.2m × 0.25m, a mass of approximately 1.2-1.4t, and an installation elevation of approximately 18m above the water surface. Obstacles such as hoisting booms, transverse diaphragms, wind surges, and monitoring cables exist around the work area. To complete the installation without interrupting traffic and navigation, this patented multi-UAV collaborative hoisting system is employed: take-off and landing points and safety buffer zones are set up in the bridge deck emergency zone; a three-dimensional model of "bridge deck—abdomen—bottom" is created using BIM overlay laser scanning; dynamic geofencing and a no-fall zone are set up above the waterway; and the flight corridor is arranged horizontally by the component's outer dimension + 2-3m and vertically by the height + 3m. The aforementioned digital path and clearance system prioritizes "whether it is flyable, how to approach, and speed / altitude boundaries" as control conditions, reducing temporary road closures and scaffolding erection without disrupting traffic.

[0056] The crane fleet consists of four multi-rotor aircraft working in coordination, each with a rated load of ≥300-400kg. Conical guides and a combination of magnetic and mechanical locking devices are pre-installed on the back of the components, and support saddles and bolt fixing points are set at corresponding locations on the bridge bottom. The initial lifting values ​​at the four points are allocated at 30%, 30%, 20%, and 20%, and are adaptively fine-tuned according to center of gravity drift. Each crane is equipped with a winch length-changing mechanism (step distance ≤10mm) and a tension / attitude sensor (50-100Hz), with a control bus delay ≤100ms. The ground station is located in a temporary maintenance vehicle on the bridge surface, linked to the bridge monitoring system and navigation radar to obtain early warnings of approaching ships. After lifting, the crane moves down to the box girder cavity through openings or maintenance holes on the bridge deck, and then cruises under the bridge at a speed of 2.0-2.5m / s through the web window. The control targets are a swing angle |θ| ≤3° and a tension deviation of ≤±8% at each lifting point. When crosswinds or backflows cause the sway to exceed the limit, a coordinated sway suppression mechanism of "deceleration - attitude differential - winch ΔL fine adjustment" is triggered, and the load is dynamically balanced by nearby points according to the threshold, thereby reducing visual interference to traffic flow from an organizational level.

[0057] Upon entering the near field, the overall speed is reduced to 0.4 m / s, and then increased to 0.05-0.10 m / s for a synchronized slow release approximately 0.5-0.8 m above the target. The cone-shaped guide enters the socket, and the fit is confirmed by the stroke or contact pressure threshold; the electromagnetic device first attracts and stabilizes the machine, then performs mechanical locking and completes the initial tightening of the bolts. The sequential unloading follows the sequence of "two machines stabilizing the load—two machines releasing the hook—the stabilizing machine unloading last," during which the levelness is continuously corrected to ≤0.2° and the gap with the edge is ≤6–8 mm. If gusts of wind ≥8 m / s, an approaching vessel alarm, or any tension deviation at any lifting point ≥±12%, the machine group will be controlled to descend to the bridge buffer zone or transferred to a standby point according to the abnormal strategy, and will proceed to the site after conditions are restored. The operation window is controlled to complete the installation of a single component and write back the flight trajectory, load time history, attitude and positioning deviation data within 00:40-04:00. This data is used for adaptive parameter optimization and maintenance quality traceability of subsequent adjacent work stations, enabling safe and high-precision component installation under the premise of uninterrupted traffic and air traffic.

[0058] In this embodiment, the key technologies of this patent are transformed on-site as follows: ① Multi-machine collaboration and load distribution + winch fine-tuning linkage to suppress sway, enabling components to pass stably in the bridge side return flow zone; ② BIM 3D corridor and dynamic geofence solidify the navigation red line as a control boundary, avoiding large-scale road closures and scaffolding; ③ A self-alignment link of "cone insertion guidance - magnetic attraction stabilization - mechanical locking - sequential unloading" improves the success rate of first-time seating and locking, shortens night window occupation, and reduces additional disturbance to existing structures; ④ Combined near-field positioning in a weak GNSS environment (UWB, vision, and reflective target smooth relay) ensures millimeter-level positioning; ⑤ Automatic writing back of operation data supports acceptance and rapid convergence of subsequent batch node parameters. Thus, in the bridge maintenance scenario of "uninterrupted traffic, weak satellite, dense obstacles, and restricted navigation," this patented solution achieves high-quality aerial hoisting with "less closure, less disturbance to residents, and replicability." Compared with traditional under-bridge erection and large crane solutions, it significantly reduces the impact on traffic organization and temporary structural loads, and improves the consistency and efficiency of continuous night window operations.

Claims

1. A hoisting construction method based on unmanned aerial vehicles (UAVs), characterized in that, This includes the following steps, and there are clear dependencies and triggering relationships between each step: A. Modeling and benchmarking: Establish a digital model that includes the site environment, obstacles, no-fly zones, target installation posture, and component parameters, and determine the coordinates and time benchmarks as a unified reference for subsequent calculations and control; B. Task allocation and synchronization: Based on the component parameters and UAV capabilities in step A, determine the role and payload share of at least one UAV participating in the operation, form a collaborative timing and communication synchronization strategy, and obtain the allocation results for collaborative control; C. Safety passage and dynamic geofence: Based on steps A and B, a three-dimensional safety passage from the lifting point to the installation point is generated, and a dynamic geofence that can be automatically updated according to changes in the environment and construction status is established. Its constraints serve as boundary conditions for flight path, approach speed and altitude control. D. Closed-loop control during the transportation phase: Control the UAV to fly along the channel and trajectory of step C, and collect data on component swing, sling force, attitude and speed; Based on the load distribution in step B and the fence constraints in step C, adjust the attitude, thrust, flight speed and (when a winch device is available) sling length of each UAV in a coordinated manner to keep the swing and force within a preset safe range. E. Near-field alignment and locking: When the conditions for entering the near field are met (including position, velocity and swing state meeting preset thresholds), switch to near-field positioning mode, perform small-range pose fine-tuning, and guide the self-alignment interface of the component and the installation part to lock and fix it; after locking, unload and detach in a predetermined sequence to maintain attitude stability. F. Data Recording and Write-back: The trajectory, attitude, force and environmental information, and actual installation position are recorded throughout the entire process of steps D and E. The data is then written back to the building information model or digital twin for acceptance and traceability, and the allocation parameters in step B and the fence and passage parameters in step C are updated accordingly to optimize subsequent operations. G. Safety and Abnormal Handling: During steps D and E, when events such as sudden changes in wind field, communication abnormalities, or decreased single-unit capabilities are detected, one or more of the following actions are executed according to a preset strategy: deceleration, weight redistribution, path replanning, controlled descent, return to home, or rapid release. The state machine controls the suspension, rollback, or resumption of the process.

2. The method according to claim 1, characterized in that, The component is hoisted by at least two drones using multi-point slings. The task allocation step includes allocating the corresponding hoisting weight and flight mission parameters according to the load capacity of each drone, and coordinating and controlling the attitude and traction of each drone to maintain the balance and stability of the component during transportation.

3. The method according to claim 1, wherein, The dynamic geofence is generated based on on-site obstacle and no-fly information, component outline and load distribution, environmental perception and construction status, and is automatically updated when personnel approach, temporary obstacles appear or wind field changes. The update results are used for speed limit, height limit, turning and approach strategies, and serve as one of the conditions for triggering abnormal handling.

4. The method according to claim 1, wherein, The closed-loop control of the transportation phase adopts a combined feedback of oscillation and force, combined with speed feedforward and attitude compensation, and adjusts the equivalent oscillation characteristics by changing the length of the sling when a hoisting device is available, thereby reducing resonance and impact.

5. The method according to claim 1, wherein, The near-field positioning employs one or more of satellite-enhanced positioning, vision, ultra-wideband, or laser ranging, and smoothly switches from far-field positioning to near-field positioning when entering the near field, in order to achieve low-speed fine-tuning and slow descent.

6. The method according to claim 1, wherein, The self-alignment interface includes an alignment unit for automatic guidance and alignment when there is an initial position and attitude deviation, and a holding unit for maintaining a stable connection after alignment. The unit can be mechanical, magnetic, adsorption, threaded, wedge-shaped, snap-fit, electromagnetic, pneumatic, or a combination thereof, and can be passive or active with a small-stroke actuator.

7. The method according to claim 1, wherein, After locking is completed, unloading includes maintaining the attitude stability of the machine and unloading the remaining UAVs in a preset order to reduce disturbance to the attitude of the components.

8. The method according to claim 1, wherein, The data recording and write-back includes the acquisition, storage, and signing of flight trajectory, attitude, force and environmental parameters, as well as the final installation posture, and is used to update the digital model and subsequent process plans.

9. The method according to claim 1, wherein, In scenarios with ground, bridge, platform, or ship anchor points, an external winch is set up to bear at least part of the vertical force or slow down the release process, while the UAV performs fine adjustment of attitude and position, and the two work together to complete alignment and locking.

10. The method according to claim 1, wherein, An integrated drone station can be set up in the construction area for mission scheduling, energy replenishment, communication relay and positioning reference services, and to provide continuous operational support for steps B to F.

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