Airborne contact-type working robot with elastic redundancy compensation and control method

Abstract

This invention provides an airborne contact work robot with elastic redundancy compensation and its control method, comprising: a UAV flight platform; a forward working arm, which is hinged to the UAV via a damped adjustable hinge mechanism; a working end actuator, located at the end of the working arm and having an independent walking drive module; an elastic redundancy compensation mechanism, located between the working arm and the working end actuator, for providing normal buffering and pressure adhesion; and a collaborative control system. This invention adjusts damping according to the contact state between the working end actuator and the work surface: maintaining high damping during flight to suppress long-arm swaying, and switching to low damping during wall-hugging to achieve attitude decoupling; simultaneously, establishing a constant-pressure closed loop using the compression of the elastic mechanism as feedback, allowing the working end actuator to autonomously walk and complete wall-hugging operations. This invention significantly improves the safety, stability, and work quality of high-altitude contact work through a layered closed loop of safe distance isolation, attitude decoupling, constant-pressure wall-hugging, and swaying suppression.

Description

Technical Field

[0001] This invention relates to the field of aerial contact work robot technology, and more specifically, to an airborne contact work robot with flexible redundancy compensation and its control method. Background Technology

[0002] For a long time, the cleaning and maintenance of high-rise building curtain walls, especially glass curtain walls, has mainly relied on suspended platforms, ropes, or manual high-altitude suspending methods. This approach is highly dangerous, labor-intensive, and its efficiency is significantly affected by weather and worker skill. With the increasing number of high-rise and super high-rise buildings, curtain wall cleaning is gradually shifting from manual methods to robotic and unmanned operations. Previous reviews have systematically classified glass curtain wall cleaning robots according to their attachment methods, climbing / movement methods, cleaning methods, and obstacle-crossing capabilities. Meanwhile, recent reviews of wall-mounted robots indicate that related technologies have evolved from single-plane wall attachment to curved surface navigation, cross-wall transitions, environmental perception, and coordinated control. However, stability, adaptability, and engineering efficiency in complex environments remain major bottlenecks.

[0003] One existing technology involves suspending a cleaning robot on ropes or a lifting mechanism, and incorporating adsorption, cleaning, and obstacle-crossing mechanisms on the robot body. For example, Chinese invention patent CN109717786A (“A Glass Curtain Wall Cleaning Robot System”) discloses a system comprising a robot body, a mobile platform, and a lifting device. The lifting device includes a DC motor, a winding bar, a winding wheel, a soft rope, and a fixed pulley; the robot body includes a supporting chassis, a cleaning device, an adsorption device, a dust collection device, and a camera gimbal. In this design, two cleaning discs are mounted on the lower surface of the chassis, and four ducted fans on both sides form an adsorption structure, relying on the upper lifting system to achieve overall lifting operations. In similar solutions, CN115886656A (“Curtain Wall Cleaning Robot”) utilizes a coordinated approach of traction ropes, a telescopic platform, and adsorption components: when the robot overcomes obstacles, the front end of the telescopic platform contacts the obstacle, and multiple adsorption components alternately adhere to the obstacle as it moves; during cleaning tasks, when the telescopic components extend to a distance equal to or greater than the gap in the curtain wall, the traction ropes deflect away from the curtain wall, thus forming an inward bowing force, which, together with the adsorption force, provides the wall-adhering force required for cleaning. CN218738667U (“Curtain Wall Cleaning Robot”) discloses another approach: multiple support legs are installed on the robot body, connected to the multi-degree-of-freedom rotation of the body. The ends of the support legs are equipped with wheels, which support the surface to be cleaned in the cleaning state, and raise the body and wheels to the obstacle-crossing height in the obstacle-crossing state.

[0004] Another type of existing technology involves directly mounting the cleaning actuator on the drone's fuselage, allowing the drone to directly approach the curtain wall to perform spraying, brushing, or scraping. CN104787342A ("A Curtain Wall Cleaning Method Based on a Drone") discloses a scheme for a quadcopter drone carrying a cleaning fluid circulation device and a cleaning device. In this scheme, the drone includes a fuselage, four propeller engines, a flight control system, a cleaning fluid circulation device, and a cleaning device; the cleaning device is equipped with guide rails, sliders, spray nozzles, return nozzles, brushes, and scrapers. During operation, the drone is controlled by ground flight control to observe image information and, after reaching its position, the sliders reciprocate along the guide rails to perform spraying and scraping. The wastewater is then recycled through a coarse filter, a wastewater tank, a negative pressure generator, a clean water tank, and a fine filter. CN120052759A ("A Tethered High-Pressure Six-Axis Curtain Wall Cleaning Drone") discloses a scheme for arranging a water storage tank, a built-in pump, an alloy direct spray bar, and an atomizing foam-spraying unit under the fuselage of a six-axis drone, focusing on rinsing the curtain wall through high-pressure spraying and foam water. The common feature of this type of technology is that the cleaning actuator is directly fixed to the drone body or a part near the drone body, and the drone itself undertakes the near-wall positioning, normal contact and operation mechanism support.

[0005] A closer type of technology to this invention utilizes drones or rotor thrust for wall adhesion, wall movement, or near-wall contact. CN115892275A (“A Wall-Climbing Robot Based on Drone Collaboration”) discloses a scheme that integrates a rotor mechanism, robotic arm, linkage support, walking wheel set, drive wheel, hydraulic cylinder, guide wheel, and track on its main structure. In this scheme, the total pulling force of the four rotor mechanisms provides the robot with an adhesive force, allowing it to overcome its own gravity and adhere to the wall; the track and linkage support are used for forward movement, turning, and obstacle crossing. When necessary, by adjusting the inclined section at the bottom of the track and controlling the rotor, it can cross protruding crossbeams. CN117163291A (“Wall Painting Drone and Wall Painting Method”) also discloses another near-wall control approach: the drone is equipped with a self-stabilizing platform, a nozzle, a detection housing with a rolling ball, a distance detection component, and a pressure detection component. During control, the appropriate distance to the wall is determined by the pressure applied to the rolling ball, and the nozzle movement distance is calculated based on the rolling distance, thereby adapting to uneven wall surfaces and improving printing accuracy. This type of technology is relevant to this invention in that it also focuses on pressure / distance control and operational accuracy in near-wall conditions.

[0006] In academic research and engineering prototypes, there exists a class of "aerial contact operation" technologies highly relevant to this invention. Since 2019 / 2020, research on aerial robotic arms has gradually shifted from free-flight grasping to contact-based detection, contact-based maintenance, and surface operations. The 2022 paper "Contact Force-Velocity Control for a Planar AerialManipulator" proposed that for a planar aerial robotic arm, hybrid force / velocity control can be used to simultaneously track the desired normal contact force with a vertical wall and the contact point velocity along the wall. The 2024 paper "Compliant ContactForce Control for Aerial Manipulator…" further proposes treating the multi-rotor platform and the robotic arm as two mutually perturbing subsystems: the drone platform primarily provides a fixed aerial fulcrum, while the robotic arm functions as an operating tool; outer impedance control converts the desired contact force into a desired position trajectory, while inner position control is responsible for tracking, thus achieving compliant contact. Another 2024 paper, "A coordinated framework of aerial manipulator for safe and compliant physical interaction," also addresses the core issue of "how to ensure the compliance and safety of the aerial manipulator when it comes into contact with the environment." These technologies are most directly related to this invention: they have touched upon core issues such as coupling between the aerial platform and the contact actuator, compliant contact, and maintenance of normal force, but the focus of disclosure is usually on control algorithms or general contact devices.

[0007] A comprehensive analysis of the existing technologies reveals the following drawbacks: First, while existing rope-based and adsorption-based curtain wall cleaning robots can achieve wall-hugging movement and partial obstacle crossing, they typically rely on roof lifting systems, rope working surfaces, negative pressure adsorption, or fan adsorption. These systems are complex to deploy and highly sensitive to the geometry, sealing, and obstacle conditions of the working surface. Even with obstacle-crossing structures, the overall operation mode remains "robot as a whole adhering and moving," making it difficult to simultaneously handle rapid high-altitude, cross-area transport and close-to-wall fine cleaning. The existing technologies themselves explicitly state that vacuum adsorption requires high wall flatness and has low stability and adaptability, while magnetic adsorption is limited by the wall material.

[0008] Secondly, while directly fixing the spraying or wiping device to the drone's body improves accessibility, structurally the drone typically performs multiple tasks simultaneously, including "reaching the target area, maintaining relative position in front of the wall, providing normal contact, supporting the cleaning mechanism, and counteracting contact disturbances." Based on its publicly available structure, it can be inferred that this type of solution lacks a dedicated long-stroke, compliant, redundant force chain between the cleaning actuator and the drone's body. This makes the normal pressure more susceptible to influences from drone attitude adjustments, gusts of wind, and near-wall control errors, making it difficult to generate a stable, continuous, and precisely configurable adhesion force.

[0009] Third, most existing drone-assisted wall-mounted robot or near-wall contact solutions still rely on the same platform to simultaneously perform wall adhesion, pressure holding, and in-plane movement on the wall. For example, in CN115892275A, the total thrust of the rotor provides the adhesion force, while the tracks complete the wall movement; in CN117163291A, the drone directly drives the nozzle to move along the wall. These structures demonstrate that existing technologies typically do not completely separate "macroscopic cross-area transport and normal pressure holding" from "microscopic wall-mounted omnidirectional scrubbing movement," thus making it difficult to achieve a collaborative mode where "the drone is only responsible for pressure holding and following, while the scrubbing head independently moves omnidirectionally on the curtain wall."

[0010] Fourth, regarding the connection between the drone and the cleaning head, while existing technologies include wall-mounted self-stabilizing platforms, three-point contact wall-mounting, compliant contact control, and universal ball joint locking devices, none of these representative solutions directly address the high-altitude curtain wall cleaning scenario by maintaining a hinged connection throughout the flight and working states. Specifically, this solution uses gravity balancing and a damped-spring hinge design to suppress the tilting and oscillation of the connecting rod under gravity during flight, and further reduces or removes the hinge damping during the wall-mounting cleaning phase, allowing the cleaning head to conform more compliantly to the curtain wall. In other words, most existing technologies do not specifically address the following issue: during the flight phase, instead of a rigid connection between the drone and the cleaning head, a continuous hinged connection combined with gravity balancing and a damped-spring system is used to balance attitude stability during flight and dynamic suppression of the connecting rod; during the contact cleaning phase, the direct interference of the drone's attitude adjustment on the cleaning head's state is reduced by removing or reducing the hinge damping.

[0011] Fifth, while existing research on aerial contact operations has recognized the coupling problem between normal contact force and wall-mounted motion control, and has proposed methods such as impedance control, mixed force, and velocity control, its typical targets are mostly probes, lightweight end effectors, or the end contacts of general robotic arms, with a focus on compliant interaction at the control level. For long-arm curtain wall cleaning configurations with "a relatively heavy cleaning head that can move independently in all directions at the front end, significant counterweight at the rear end, and a large system yaw inertia," existing publicly available solutions do not adequately disclose the systematic engineering implementation issues of removing resistance after contact, maintaining pressure, synchronous following, and adding hinge damping-springs during withdrawal.

[0012] Therefore, existing technologies still need to provide a new airborne curtain wall cleaning robot solution that can simultaneously achieve: stable and controllable pressure force output, independent walking of the scrubbing head on the curtain wall surface, and connection state switching between flight mode and wall-adhering operation mode in high-altitude environments, and form a systematic technical closed loop of "safe distance - attitude decoupling - constant pressure wall adhesion - vibration suppression". Summary of the Invention

[0013] In view of the deficiencies in the prior art, the purpose of this invention is to provide an airborne contact robot with flexible redundancy compensation and a control method thereof.

[0014] An airborne contact robot with elastic redundancy compensation according to the present invention includes: Unmanned aerial vehicle (UAV) flight platform; The first end of the working arm assembly is hinged to the UAV flight platform via a connection mechanism that allows the working arm assembly to deflect attitude relative to the UAV flight platform. The working end actuator is disposed at the second end of the working arm assembly and includes a moving module for autonomous movement on the working surface; An elastic redundancy compensation mechanism is disposed between the second end of the working arm assembly and the working end actuator to provide buffer stroke and adhesion force along the normal direction of the working surface; The collaborative control system is communicatively connected to the flight control system of the UAV flight platform and the operating end actuator, respectively. The collaborative control system is used to: when the actuator at the working end is in contact with the working surface, control the UAV flight platform to provide normal thrust to the actuator at the working end, and at the same time control the UAV flight platform to move with the actuator at the working end.

[0015] Preferably, the system further includes a constraint adjustment component, which works in conjunction to apply adjustable constraints to the swing of the working arm assembly relative to the UAV flight platform, and the UAV flight platform and the working arm assembly include a first connection state and a second connection state based on different constraints; During the flight transport phase, it enters the first connection state to suppress the swaying of the working arm assembly; During the wall-hugging operation phase, once it is determined that the working end actuator has reliably adhered to the wall, the connection state is switched from the first connection state to the second connection state, thereby releasing the sway suppression of the working arm assembly and reducing the interference of the UAV flight platform attitude correction on the working end actuator.

[0016] Preferably, the collaborative control system is further used for: During the wall-hugging operation phase, a normal correction command is generated based on at least one contact state quantity of the elastic redundancy compensation mechanism and / or the working end actuator, and sent to the flight control system of the UAV flight platform to fine-tune the position of the UAV flight platform along the normal of the working surface in a closed-loop manner, so that the compression or pressure is maintained at the target value. The positional deviation of the working end actuator relative to the UAV flight platform and / or the angular displacement of the working arm assembly relative to the center position are obtained, and a plane-following command is generated to control the UAV flight platform to passively follow within the working plane.

[0017] Preferably, the collaborative control system is further configured to perform evacuation safety interlock control, including: When the operation is completed or interrupted, the drone flight platform is controlled to adjust its position so that the working arm assembly meets the preset centering conditions. After the preset alignment condition is met, the connection is restored to the first connection state; After confirming the restoration to the first connection state, control the UAV flight platform to retreat and release the compression or pressure of the elastic redundancy compensation mechanism; The drone flight platform is only permitted to perform an evacuation maneuver after the compression or pressure has been released to the safe release range.

[0018] Preferably, the collaborative control system is further used for: The angular displacement and angular velocity of the working arm assembly are acquired in real time. When the product of the angular displacement and the angular velocity is greater than zero, the system enters the first connection state. When the product of the angular displacement and the angular velocity is less than zero, the system enters the second connection state.

[0019] Preferably, it further includes: a counterweight assembly configured to adjust the torque balance of the system to compensate for the off-center load torque generated by the boom assembly and the end effector; The collaborative control system is also used for: Obtain the real-time compression amount of the elastic redundancy compensation mechanism; The eccentric load moment is calculated based on the real-time compression amount. Based on the eccentric load moment, the counterweight assembly is driven to adjust its position to balance the eccentric load moment.

[0020] Preferably, the collaborative control system is further used for: Obtain the feature values ​​of the obstacle in front of the working end actuator; When the obstacle feature quantity is less than or equal to a preset threshold, the operating end actuator is controlled to start the autonomous obstacle-crossing mode; When the obstacle feature value is greater than a preset threshold, or when autonomous obstacle crossing fails, the operator controls the working end actuator to pause walking and controls the UAV flight platform to perform posture adjustment actions to assist in overcoming obstacles.

[0021] Preferably, a pneumatic auxiliary device is further provided at the second end of the working arm assembly and / or at the working end actuator, the pneumatic auxiliary device being used to output pneumatic force to assist in adjusting the state of the end of the working arm assembly.

[0022] Preferably, the working arm assembly is a length-adjustable structure, including an arm segment that can move relative to the working arm assembly along its axial direction, so that the overall length of the working arm assembly can be adjusted within a preset range.

[0023] Preferably, the collaborative control system is further configured to: limit the yaw rate to within a preset upper limit under all operating conditions, and adopt a lower yaw rate limit during the wall-hugging operation phase than during the flight transport phase; when a change of course is required while in the wall-hugging state, control the UAV flight platform to sequentially execute the following actions: retreating along the normal direction of the work surface to a preset safe distance, yawing to the target course, and reapproaching the work surface. A control method for an airborne contact-type work robot with elastic redundancy compensation provided by the present invention includes the following steps: Step S1: During takeoff and transport, enter the first connection state and suppress the swing of the working arm assembly; Step S2: Approaching the work surface stage, control the UAV flight platform to approach the work surface in the normal direction until the work end actuator contacts the work surface and causes the elastic redundancy compensation mechanism to compress; Step S3: Contact determination stage. When the compression amount or contact pressure of the elastic redundancy compensation mechanism is detected to reach a preset threshold and stabilize, it is determined that the actuator at the working end has reliably adhered to the wall. Step S4: Switching and operation phase, switching from the first connection state to the second connection state, and establishing pressure-adhesion closed-loop control to maintain the compression amount or pressure of the elastic redundancy compensation mechanism at the target value, while controlling the operation end actuator to move autonomously on the operation surface to perform contact operation.

[0024] Preferably, it also includes an evacuation step: When the operation is completed or interrupted, the drone flight platform is controlled to adjust its position so that the working arm assembly meets the preset centering conditions. After the preset alignment condition is met, the connection is restored to the first connection state; After confirming that the connection has been restored to the first connection state, control the UAV flight platform to retreat and release the compression or pressure of the elastic redundancy compensation mechanism; The UAV flight platform is only allowed to perform an evacuation action after the compression or pressure of the elastic redundancy compensation mechanism has been released to the safe release range.

[0025] Preferably, the pressure-adhesion closed-loop control includes: Obtain the real-time compression amount or real-time contact pressure of the elastic redundancy compensation mechanism; Based on the difference between the real-time compression amount and the target compression amount, or the difference between the real-time contact pressure and the target contact pressure, a normal correction command is generated. The normal correction command is sent to the flight control system of the UAV flight platform to fine-tune the position of the UAV flight platform along the normal of the working surface, so that the compression or pressure of the elastic redundancy compensation mechanism is maintained near the target value.

[0026] Preferably, the switching between the first connection state and the second connection state includes: acquiring the angular displacement and angular velocity of the working arm assembly in real time; when the product of the angular displacement and angular velocity is greater than zero, entering the first connection state to dissipate the kinetic energy of the working arm with high damping; when the product of the angular displacement and angular velocity is less than zero, entering the second connection state to allow the working arm to quickly return to center under the action of restoring force with low damping; and maintaining the current connection state when both the angular displacement and angular velocity are within a preset dead zone range.

[0027] Preferably, the method further includes a dynamic counterweight balancing step: acquiring the compression displacement of the elastic redundancy compensation mechanism in real time; calculating the front equivalent force arm and estimating the off-center load torque based on the compression displacement and the pre-calibrated geometric mapping relationship; and driving the counterweight assembly to adjust its position along the guide rail based on the off-center load torque, so that the difference between the front and rear torques is maintained within a preset balance tolerance range.

[0028] Preferably, the method further includes a graded obstacle-crossing step: acquiring the obstacle feature quantity in front of the working end actuator; when the obstacle feature quantity is not greater than a preset first threshold, controlling the working end actuator to autonomously cross the obstacle at an obstacle-crossing speed, and the UAV flight platform maintaining a constant pressure closed loop without performing large movements; when the obstacle feature quantity is greater than the first threshold, or when the autonomous obstacle crossing is not completed within a preset time period, controlling the working end actuator to pause walking, controlling the UAV flight platform to first retreat a preset distance along the normal direction, and then vertically lift, driving the working end actuator to cross the obstacle and then re-execute the pressing and contact determination process.

[0029] Preferably, it also includes a low yaw safety control step: under all working conditions, the yaw rate is limited to not exceeding a preset upper limit, and a lower yaw rate limit is adopted during the wall-hugging operation phase; when it is necessary to change the course in the wall-hugging state, a three-stage maneuver is performed in sequence: retreating along the normal of the working surface to a preset safe distance, yawing to the target course, and reapproaching the working surface.

[0030] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention adopts a physical architecture that combines a UAV flight platform with a forward-facing long cantilever working arm, pushing the working end actuator to the forward working area away from the UAV body. This achieves a safe distance isolation between the UAV body and the working surface, avoiding the risk of high-speed rotor near-wall turbulence and collision, while retaining the multi-rotor platform's high load capacity, maneuverability, and obstacle crossing capabilities.

[0031] 2. This invention establishes an electrically controlled ball joint connection mechanism with adjustable damping between the UAV and the forward working arm. During the flight transport phase, it maintains high damping to suppress the swing of the long arm, and switches to low damping to release constraints during the wall-hugging operation phase. At the same time, through the working end actuator of the independent walking drive module, it achieves effective decoupling between the attitude correction of the UAV and the motion state of the working end actuator, forming a master-slave collaborative mode of macroscopic pressure holding and following, and microscopic autonomous walking.

[0032] 3. This invention establishes a constant pressure closed-loop control by setting an elastic redundancy compensation mechanism between the long arm and the working end actuator, and using compression displacement or contact pressure as feedback quantity. At the same time, the position of the counterweight is adjusted in real time according to the elastic compression quantity at the front end to maintain the dynamic balance of the overall torque. This realizes the transformation of the drone position fluctuation, airflow disturbance and uneven wall surface into a stable and controllable pressure force output, avoids the pressure change caused by rigid top contact, significantly reduces the anti-slip friction requirement of the working end actuator on the working surface, and improves the wall adhesion stability and cleaning uniformity.

[0033] 4. This invention employs an asymmetric dynamic damping control strategy based on the relationship between angular displacement and angular velocity (high energy consumption during the swing-out phase and low energy release during the return phase), combined with a rigid interlocking sequence of "centering → restoring high damping → releasing pressure attachment → allowing retreat" during the withdrawal phase, and safety control that limits yaw angular velocity and prohibits sharp turns under all operating conditions for large yaw inertia configurations. This invention achieves rapid return to center without overshoot after gust disturbances, strict prohibition of direct retreat under low damping conditions, and safe and controllable flight of the large inertia long arm system throughout the entire process, fundamentally eliminating the risks of pendulum swing, crash swing, and near-wall collisions that could cause the aircraft to crash. Attached Figure Description

[0034] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic diagram of the overall structure of the curtain wall cleaning robot provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the working surface of the wiping head and moving module structure provided in an embodiment of the present invention; Figure 3This is a schematic diagram of the back of the cleaning head and moving module structure provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the forward working arm assembly of the scrubbing head and moving module structure provided in an embodiment of the present invention.

[0035] Explanation of reference numerals in the attached figures: Detailed Implementation

[0036] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0037] In various embodiments of the present invention: (1) The connection mechanism is not limited to ball joints, but can also be any connection form that allows the working arm to deflect its attitude relative to the UAV flight platform, such as universal joints, cross joints, single-axis pitch joints, flexible compliant joints, etc. (2) Constraint adjustment can be achieved through at least one of damping adjustment, stiffness adjustment, friction adjustment, clutch engagement / disengagement, locking / unlocking, and the adjustment actuator can be driven by a motor, pneumatic, hydraulic or mechanical means; (3) The torque balancing component is not limited to a movable counterweight, but can also be a center of gravity adjustment mechanism that utilizes the movement of existing functional components (such as battery packs and control boxes), or other devices that can adjust the torque balance of the system; (4) The contact state quantity is not limited to compression displacement and contact pressure, but may also be driving current, strain, displacement deviation or a combination thereof; (5) End-effectors include, but are not limited to: curtain wall cleaning module, spraying module, ultrasonic flaw detection / non-destructive testing module, rust removal and grinding module, etc. This embodiment takes curtain wall cleaning as an example for detailed description, but the scope of protection is not limited to the cleaning field.

[0038] (6) The following implementation parameters (including arm length, damping coefficient range, elastic stroke, clamping force, speed limit, angle threshold, time criterion, etc.) are all exemplary values ​​used to illustrate the technical effects that the present invention can achieve, and do not constitute a limitation on the scope of protection. In practical applications, the above parameters should be adaptively adjusted according to factors such as the payload capacity of the UAV platform, the material of the working surface, the building height, and climatic conditions.

[0039] (7) The connection mechanism can be a single-degree-of-freedom connection mechanism or a multi-degree-of-freedom connection mechanism. This embodiment takes a multi-degree-of-freedom connection mechanism as an example and specifically elaborates on a multi-degree-of-freedom connection mechanism (electrically controlled ball joint connection mechanism), but the protection scope is not limited to this.

[0040] This specific implementation will focus on the technical main line of "safe distance - attitude decoupling - constant pressure wall adhesion - vibration suppression", and in a progressive manner, fully demonstrate how the present invention solves a series of technical contradictions in high-altitude curtain wall cleaning, and finally forms a safe, stable and efficient system solution.

[0041] 1. Safe distance In existing curtain wall cleaning technologies, although wall-climbing robots can operate close to the wall, they are complex to deploy, highly dependent on wall conditions, have low efficiency in cross-regional transfer, and have limited obstacle-crossing capabilities. On the other hand, if traditional drones carry the cleaning head directly to operate close to the wall, their high-speed rotors are extremely close to the curtain wall, making them susceptible to near-wall turbulence and gusts of wind, resulting in significant risks of collision with the wall and instability.

[0042] To resolve the initial conflict between safety and accessibility, the airborne curtain wall cleaning robot with flexible redundancy compensation provided in this embodiment includes: a drone flight platform 1, a forward working arm assembly 2, a scrubbing head assembly 3, an electrically controlled hinged damping connection assembly 4, an electrically controlled ball joint connection mechanism 5, a flexible redundancy compensation mechanism 6, a sensing system 7, a collaborative control system 8, and a counterweight assembly 10 (including an electrically controlled mechanism 9 and a rearward-extending counterweight support rod and counterweight block 10).

[0043] The UAV flight platform 1 is preferably a multi-rotor UAV platform, such as a six-axis or eight-axis configuration, but other flight platforms with sufficient payload capacity and attitude control accuracy can also be used; this invention is not limited to a specific number of rotor shafts or aircraft configuration. The UAV flight platform 1 has a main frame, a power system (motor, propeller), a flight controller, a power system (lithium battery pack or tethered power supply interface), and multiple payload mounting interfaces. The platform's payload capacity meets the requirements for carrying the forward working arm assembly 2, the cleaning head assembly 3, and the counterweight assembly 10. The flight controller has a built-in inertial measurement unit (IMU), magnetic compass, barometric altimeter, GPS / RTK positioning module, and visual navigation module, enabling stable hovering, low-speed translation, and attitude control in complex high-altitude environments.

[0044] The forward working arm assembly 2 is located at the front of the UAV, with a preferred total length of 3.5 meters. This arm body utilizes a carbon fiber composite material or aluminum alloy truss structure to minimize weight while ensuring rigidity. The arm body includes an arm root connection end, a main load-bearing structure, and an arm end connection end. The arm root connection end is hinged to a pre-set mounting base at the front of the UAV body via an electrically controlled ball joint connection mechanism 5; the arm end connection end is connected to the scrubbing head assembly 3 via an elastic redundancy compensation mechanism 6, which provides buffer travel and adhesion force along the curtain wall normal. The forward working arm has three main functions: first, to push the scrubbing head assembly 3 to a safe distance (approximately 3.5 meters) in front of the UAV, avoiding near-wall turbulence affecting flight safety; second, to provide a low-impedance transmission path for the normal adhesion force output by the UAV; and third, to act as the front lever arm of the counterweight assembly 10, jointly maintaining the overall torque balance of the aircraft.

[0045] In an optional embodiment, a pneumatic auxiliary device may be provided at the second end of the forward working arm assembly 2 or near the scrubbing head assembly 3. The pneumatic auxiliary device can operate during the drone's approach to the curtain wall, hovering transition, or when subjected to wind disturbance, by outputting pneumatic force to assist in adjusting the state of the forward working arm's end, thus complementing the aforementioned arm root damping hinge mechanism in terms of operating position and response characteristics. The specific structural form, installation orientation, number, and control strategy of the pneumatic auxiliary device, as well as its start-stop coordination with the wall-hugging state, can be implemented appropriately by those skilled in the art based on specific application scenarios. This pneumatic auxiliary device can be installed independently or work in conjunction with the aforementioned electrically controlled hinged damping connection assembly 4 and the rear counterweight assembly 10.

[0046] In another optional embodiment, the forward working arm assembly 2 of the present invention is not limited to a fixed-length structure, but can also adopt a length-adjustable structure, that is, it includes two or more arm segments that can move relative to each other along the axial direction, so that the overall length of the forward working arm can be changed within a preset range. When using this length-adjustable structure, the working arm can be kept at a shorter length during takeoff and transportation to reduce off-center load moment and air resistance; during wall-hugging operations, the working arm can be extended to a suitable working length to adapt to complex facades such as recesses, terraces, and protruding components of the curtain wall. The specific arm segment matching form, driving method, position holding method, pipeline layout method, and linkage and coordination method with the rear counterweight assembly 10 and the arm root connection mechanism during the length change of the length-adjustable structure can be implemented by those skilled in the art according to the specific application scenario.

[0047] The scrubbing head assembly 3 includes a moving module, specifically including: left and right moving tracks 11, up and down moving tracks 12, cleaning roller brush 13, a dual-pipeline mechanism for providing cleaning fluid and clean water 14, a bidirectional moving chassis 15, a roller brush drive motor 16, a passive cross universal joint and a mechanical return spring 17, and a direction switching assembly 18.

[0048] In a preferred embodiment, the passive universal joint can also be a ball joint mechanism, an elastic damping base, or other multi-degree-of-freedom compliant connection structure, and the mechanical return spring can also be a torsion spring, a rubber elastomer, or other elastic element with restoring force characteristics.

[0049] The moving module of the working end actuator includes, but is not limited to: tracked walking mechanism, omnidirectional wheel / Mecanum wheel mechanism, ordinary wheel mechanism, multi-legged walking mechanism or combination thereof; the specific configuration can be configured according to the working surface material, path planning and load requirements. In this embodiment, a dual-track structure of left and right moving tracks 11 and up and down moving tracks 12 is preferably adopted.

[0050] The dual-pipeline mechanism 14 is used to deliver cleaning fluid and clean water to the scrubbing execution part respectively; the direction switching component 18 is used to cooperate with the bidirectional mobile chassis 15 and the walking drive module to realize the switching of the working direction or the posture; the passive cross universal joint and the mechanical return spring 17 are used to provide end smooth fit and mechanical return during the scrubbing head's contact with the wall, edge transition and withdrawal centering stages.

[0051] The UAV flight platform 1 and the forward working arm assembly 2 are connected by an electrically controlled ball joint connection mechanism 5 and an electrically controlled hinge damping connection assembly 4. An elastic redundancy compensation mechanism 6 is set between the forward working arm assembly 2 and the scrubbing head assembly 3 to provide buffer stroke and pressure force along the curtain wall normal. The scrubbing head assembly 3 is set at the front end of the forward working arm assembly 2 and forms a compliant connection with the front end of the working arm through a passive cross universal joint and a mechanical return spring 17. The rear counterweight support rod and counterweight block 10 are set at the rear of the UAV and are adjusted in position through an electrically controlled mechanism 9 to form a front-rear torque balance with the front scrubbing head assembly 3.

[0052] The sensing system 7 is used to detect, collect, or calculate compression, pressure, attitude, relative pose, and ball joint connection status.

[0053] By using this drone + long cantilever architecture, the present invention successfully maintains a safe distance between the drone body and the curtain wall, reducing the risk of rotors approaching the wall. At the same time, by utilizing the multi-rotor platform's large load capacity, maneuverability, and cross-area obstacle-crossing capabilities, it realizes aerial transport, approach, and workstation switching of the cleaning end, initially solving the contradiction of needing to stay away from the wall while also reaching it quickly.

[0054] The working surfaces described in this invention include, but are not limited to, vertical or near-vertical building facades (curtain walls, exterior walls, etc.), and are also applicable to various industrial high-altitude contact work scenarios such as the outer walls of large storage tanks, bridge piers, ship hulls, and wind turbine towers.

[0055] 2. Attitude decoupling While the introduction of the long cantilever solved the safety distance problem, it immediately brought about a more intractable contradiction between flight mechanics and operational control. If the long arm remains rigidly fixed to the fuselage, the fuselage tilt and attitude correction generated when the UAV hovers against the wind at high altitude will be amplified by the lever effect of the long arm and transmitted to the cleaning end, thus compromising the stability of the wall. At the same time, relying solely on the UAV to make high-precision displacement fine adjustments from several meters away to drag the cleaning head assembly 3 to complete the wall operation is also difficult to achieve from a control engineering perspective. To completely overcome the disastrous consequences of rigid coupling, this invention creatively constructs a three-dimensional decoupling system that combines multi-degree-of-freedom articulation, autonomous end-effector movement, and radial elastic buffering, focusing on the separation between "fuselage attitude control" and "end-effector wall-hugging operation." This section focuses on the articulation and damping control in attitude decoupling.

[0056] 2.1 The electrically controlled ball joint connection mechanism 5 and the electrically controlled hinge damping connection assembly 4 The electrically controlled ball joint connection mechanism 5 is the core component for achieving the hinged connection between the UAV and the working arm. It includes: a ball head (fixed to the root of the working arm), a ball seat (fixed to the UAV body mounting base), a damping adjustment actuator, a damping transmission structure, an elastic return-centering unit, a connection status sensor, and a centering detection unit. The ball head is a high-hardness stainless steel ball with a polished surface; the ball seat is lined with a self-lubricating material (such as PTFE composite material) to ensure a low coefficient of friction. The damping adjustment actuator can adopt a motor-driven friction plate structure: the motor drives a lead screw to press or release the friction plate on the ball head surface, thereby changing the rotational resistance. Alternatively, lead screw drive, electromagnetic resistance adjustment, friction plate preload adjustment, fluid damping adjustment, or other electromechanical adjustment mechanisms can be used, with a motor-driven friction plate structure being preferred. The elastic return-centering unit consists of multiple circumferentially arranged torsion springs or tension / compression springs, providing a restoring torque when the working arm deviates from its center position. The centering detection unit includes an angle encoder or Hall sensor mounted on a ball mount, used to measure the angle of the working arm relative to the machine body in real time (including pitch and yaw angles).

[0057] The electrically controlled articulated damping connection assembly 4 can be considered as a component of the aforementioned electrically controlled ball joint connection mechanism 5, or it can be used as a separate unit. It is specifically responsible for providing a variable damping coefficient. In this embodiment, the control signal for the damping adjustment actuator comes from the cooperative control system 8. By adjusting the normal pressure applied to the ball head or the size of the damping orifice of the fluid, the equivalent damping coefficient is continuously adjustable within the range of 5~200 N·s / rad.

[0058] Through the above structure, the UAV and the working arm maintain a ball joint connection throughout the entire process. However, this connection is not a simple free hinge, but a "controlled compliant hinge" with adjustable damping and centering capabilities. This provides a physical basis for subsequent state switching control.

[0059] As an alternative, the connection mechanism can also adopt other connection forms that allow the working arm to deflect its attitude relative to the UAV flight platform, such as a cross universal joint, a single-axis pitch hinge, a flexible compliant connection mechanism, or a parallel elastic hinge structure, as long as it can achieve the constraint state switching function described in this invention.

[0060] 2.2 Variable Damping / Variable Constraint Control To achieve a complete control closed loop of "vibration suppression in flight mode, compliance in contact mode, and constant pressure in operation mode", the cooperative control system 8 executes the following variable damping / variable constraint control steps with a fixed control period (e.g., 10ms).

[0061] (1) Status signal acquisition. The following signals are acquired in real time: The angular displacement θ of the working arm relative to the center position (obtained by ball joint angle sensor and / or vision-IMU fusion); Angular velocity ω (either measured directly by the IMU or obtained by differential θ); The attitude disturbance amplitude A and frequency f of the UAV flight platform 1 (extracted from the gyroscope and accelerometer data of the flight controller, such as the bandpass filter amplitude of the roll angle and pitch angle of the aircraft). The elastic redundancy compensation mechanism compresses displacement x. Contact pressure F; Current mission status identifier S (given by the upper-level state machine, including: takeoff transport, near-wall approach, pressure attachment establishment, wall-hugging operation, dynamic wind resistance, evacuation preparation, and anomaly protection); The feedback state of the damping mechanism, Cd (actual damping coefficient or clutch engagement / disengagement state).

[0062] (2) Signal preprocessing. Low-pass filtering (cutoff frequency 10~20Hz) is performed on θ, ω, A, f, x, and F to eliminate high-frequency noise; then upper and lower limit windows are set for compression displacement x and contact pressure F (for example, the effective range of x is 0~80cm and the effective range of F is 0~100N), and a duration criterion is introduced (for example, the signal is considered valid only if it lasts for more than 0.5 seconds beyond the threshold) to avoid misjudgment of the state caused by instantaneous impact.

[0063] (3) Contact establishment determination. When x reaches the first preset compression threshold, or F reaches the first preset pressure threshold, and the stable duration is not less than the first preset duration Ton, it is determined that the wall contact has been reliably established; when x falls below the second preset compression threshold, or F falls below the second preset pressure threshold, and the duration is not less than the second preset duration Toff, it is determined that the contact has been lost or insufficient. Preferably, a hysteresis band is set between the first preset threshold and the second preset threshold to avoid repeated switching.

[0064] (4) Damping State Determination. Based on the task status indicator S and the contact determination result, select one of the following damping states: When S is in the "takeoff transport", "near-wall approach", "evacuation preparation" or "abnormal protection" state, the system enters the first connection state (high damping range). In this state, the damping coefficient is set to a higher value, such as c=150N·s / rad, to suppress the free swing of the boom.

[0065] When contact has been established but S is still in the initial stage of adhesion establishment (i.e., within 3 seconds after contact is established), the system enters a transitional damping state. The damping coefficient is taken as an intermediate value, for example, c = 60 N·s / rad, to avoid sudden reduction in damping that could cause shock.

[0066] When contact is reliably established and S enters the wall-hugging operation state, the system switches to the second connection state (low-damping range). The damping coefficient drops below 5 N·s / rad, or the clutch is fully released (approximately undamped), allowing the working arm to swing almost freely, thereby decoupling the UAV attitude correction from the motion of the scrubbing head assembly 3.

[0067] When the disturbance amplitude A exceeds the wind resistance threshold (e.g., the aircraft tilt angle is ±5° and the frequency is >1Hz), or |θ| exceeds 10° and |ω| exceeds 30° / s, even if S is still in the transportation or approach phase, it will be forcibly switched to dynamic wind resistance damping state. In this state, the damping coefficient is dynamically calculated according to the subsequent formula.

[0068] (5) Damping command calculation. For example, under dynamic wind-damped conditions, the damping command can be calculated using the following formula: Where: is the target damping coefficient (unit: N·s / rad); is the basic damping value (N·s / rad); is the gain coefficient (dimensionless); is the angular displacement of the working arm relative to the center position (rad); is the angular velocity (rad / s); is the amplitude of the UAV attitude disturbance (°); is the disturbance frequency (Hz); is the saturation function, limiting the output within the range; and are the minimum / maximum allowable damping coefficients (N·s / rad). In this way, the greater the disturbance, the higher the damping; after the disturbance weakens, the damping automatically decreases. This allows the forward working arm with counterweight to also possess the energy absorption characteristics of a tuned mass damper under gust conditions. The physical meaning of this formula is: the greater the disturbance, the higher the damping, thus using the working arm as a tuned mass damper (TMD) to absorb and dissipate the impact energy of the airflow on the aircraft.

[0069] (6) Damping Execution. The coordinated control system 8 converts the calculated target damping coefficient into the corresponding actuator signal. For motor-friction plate dampers, PID control is used to adjust the friction plate clamping force; for magnetorheological dampers, the excitation current is adjusted. If a fixed damper is used in combination with a mechanical clutch, the engagement, partial engagement, and release of the clutch correspond to high damping, medium damping, and low damping / undamped states, respectively. Additionally, if the system is equipped with limiters or adjustable preload springs, the equivalent dynamic stiffness can also be changed in a coordinated manner.

[0070] (7) Abnormal Retreat. When any of the following abnormalities are detected: compression displacement exceeds the limit (x>85cm), pressure exceeds the safety value (F>100N), UAV attitude exceeds the stability boundary (roll angle>25°), damping actuator feedback failure, communication interruption, or the working head accidentally detaches from the curtain wall (contact judgment changes from true to false), the system will immediately force a retreat to the first damping state and set the abnormal protection flag. At this time, the active movement of the scrubbing head assembly 3 is suspended. The wall-hugging operation state can only be re-established after the fault is cleared and the operator confirms.

[0071] It should be noted that the first connection state and the second connection state belong to the definition of the connection relationship level; in the specific control implementation, the first damping state, the transition damping state and the dynamic wind-resistant damping state can all be regarded as different damping sub-states under the first connection state, and the second damping state corresponds to the second connection state.

[0072] Through the aforementioned multimodal damping state machine, this invention realizes the complete logic of high-damping vibration suppression in flight state—damping transition during contact establishment—low-damping decoupling during wall-hugging operation—high-damping retreat during abnormal situations, laying the foundation for subsequent constant-pressure wall-hugging and oscillation suppression.

[0073] 2.3 Asymmetric Dynamic Damping Control Building upon variable damping control, this invention further refines the algorithm to address the problem that while traditional symmetrical damping is effective in suppressing swing-out, it also provides resistance during return to center, leading to slow return of the forward boom, oscillation tailing, and secondary swinging. Its core lies in allocating damping based on the boom's motion phase (i.e., the directional relationship between angular displacement and angular velocity) rather than solely on the magnitude of displacement, resulting in high energy consumption during the swing-out phase and low constraint or near-release during the return to center phase.

[0074] The specific steps are as follows: (1) Phase recognition. Let the angular displacement of the working arm relative to the center position be θ (with a sign, e.g., left deviation is positive and right deviation is negative), and the angular velocity be ω (counterclockwise is positive). Set the center dead zone threshold and the velocity dead zone threshold.

[0075] When |θ|≤ and |ω|≤, the system is determined to be in the intermediate stability region; When θ·ω>0, it is determined that the working arm is continuing to swing out in a direction deviating from the center (for example, if θ is positive and ω is positive, it means swinging out to the right). When θ·ω<0, it is determined that the working arm is retracting towards the center position (for example, if θ is positive but ω is negative, it means that it is returning from the right to the center position). To prevent frequent symbol jitter, an anti-jitter timer is set: the phase switch is confirmed only if the symbol of θ·ω is held continuously for more than 3 control cycles (30ms); otherwise, the phase of the previous cycle is used.

[0076] (2) Swingout phase control. When the swingout phase is identified (θ·ω>0), the system enters a high-energy-consuming damping mode. The damping coefficient increases along with both displacement and velocity.

[0077] The purpose of this stage is to quickly dissipate the kinetic energy of the swing and prevent the long arm from swinging excessively.

[0078] (3) Mid-point control. When the system is identified as being in the mid-point phase (θ·ω<0), it enters a low-constraint mid-point mode. The damping coefficient is significantly reduced. For example, the formula for calculating the damping coefficient in the mid-point phase is: Where: is the damping coefficient during the return-to-center phase (N·s / rad); ; , . When necessary, it can be set to approximately zero, retaining only the minimum damping required to prevent mechanical shock (e.g., 5). This allows the spring restoring force, gravity oscillation force, or equivalent return-to-center force to dominate the rapid return of the boom to center, without being slowed down by high damping.

[0079] (4) Mid-range stability control. When |θ|≤ and |ω|≤, the system output base maintains damping. If it is in flight transport mode, take 30 N·s / rad; if it is in wall-hugging operation mode, take 10 N·s / rad. This damping can avoid complete free swing and also avoid excessive power consumption and rigidity caused by continuous high damping.

[0080] (5) Execution. The coordinated control system 8 sends the calculated target damping coefficient (or) to the damping adjustment actuator. For adjustable dampers, the adjustment is direct; for fixed dampers and mechanical clutch mechanisms, equivalent asymmetric damping is achieved by engaging the clutch in the swing-out stage, releasing the clutch in the return-to-center stage, and partially engaging the clutch in the mid-position stage.

[0081] (6) Handling special cases. If the boom enters the centering phase at a large deflection angle (|θ|>45°), to prevent excessive impact caused by excessive centering speed, a small amount of damping proportional to |θ| can be added, for example, =10+0.5·|θ|, with an upper limit of 30N·s / rad. This correction can ensure a smooth centering process.

[0082] Through asymmetric dynamic damping control, the boom can quickly return to center without overshoot after being disturbed by gusts of wind, which significantly improves the system's wind resistance during flight and its position following accuracy during the wall-hugging phase.

[0083] 3. Constant pressure wall bonding After completing attitude decoupling, this invention further addresses the core issues of how to stably output a suitable clamping force for curtain wall cleaning and how to achieve macroscopic pressure holding by the UAV and microscopic autonomous movement of the cleaning head assembly 3. This section focuses on the elastic redundancy compensation mechanism 6, constant pressure closed loop and position following, and dynamic center of gravity adaptive balance.

[0084] 3.1 Flexible Redundancy Compensation Mechanism 6 The elastic redundancy compensation mechanism 6 is located between the forward working arm and the scrubbing head assembly 3, arranged along the normal direction of the curtain wall (i.e., the axial direction of the working arm). Its specific structure includes: a telescopic guide assembly (composed of inner and outer sleeves and linear bearings), an elastic element (preferably a parallel helical compression spring assembly, but gas springs or polyurethane elastomers can also be used), a damping-spring buffer assembly (a small hydraulic damper used to absorb high-frequency impacts), a compression displacement sensor (e.g., a lever-type potentiometer or a magnetostrictive displacement sensor), a pressure sensor (installed between the scrubbing head back plate and the spring seat, used to directly measure the normal contact force), and a stroke limiting mechanism. In this embodiment, the total buffer stroke of the elastic redundancy compensation mechanism 6 is designed to be 80cm, with an effective working stroke of 40cm. When the compression is 40cm, the normal clamping force generated by the spring assembly is approximately 50N. The core function of this mechanism is to convert the position fluctuations of the UAV caused by positioning errors, airflow disturbances, or uneven wall surfaces into the telescopic displacement of the springs, thereby outputting a relatively stable clamping force to the scrubbing head assembly 3 and avoiding rigid impacts.

[0085] 3.2 Constant Pressure Closed Loop and Position Following This embodiment details how to use the compression displacement or contact pressure of the elastic redundancy compensation mechanism 6 as the normal force closed-loop quantity, the position of the UAV flight platform 1 along the curtain wall normal as the execution quantity, and the position deviation of the cleaning head assembly 3 relative to the UAV and the deflection of the working arm as the in-plane following basis to achieve master-slave coordination of macroscopic pressure holding of the UAV and microscopic autonomous walking of the cleaning head assembly 3.

[0086] The specific steps are as follows: (1) Selection of closed-loop variables. If the system is equipped with both pressure sensors and displacement sensors, the contact pressure F is preferred as the normal closed-loop main variable, because the pressure directly reflects the degree of pressure of the scrubbing head assembly 3 on the curtain wall. If the pressure sensor fails or is not configured, the compression displacement x is used as the main variable. When both are effective, consistency verification can be performed according to the pre-calibrated elastic relationship (where k is the spring stiffness and b is the preload): if || exceeds the threshold (e.g., 10N), a sensor abnormality alarm is issued, and the system automatically switches to the displacement closed loop as a backup.

[0087] (2) Calculation of normal error. Let the target compression displacement be and the target contact pressure be . If the displacement is used as the closed loop, then the normal error is ; if the pressure is used as the closed loop, then . To avoid over-control caused by small jitters of the UAV, a normal dead zone (displacement) or ±2N (pressure) is set. Subsequent control calculations are only performed when ||>.

[0088] (3) Normal position servo. The cooperative control system 8 calculates the displacement correction Δn (unit: mm) of the UAV along the curtain wall normal direction using a PID controller based on the normal error. For example, the discretization formula for the normal position servo PID controller is: Where: is the normal displacement correction amount (mm) output in the first control cycle; is the normal error (mm or N) in the first cycle; is the control cycle (0.01s); in this embodiment, (or mm / mm), , .

[0089] After being limited (maximum single-step correction ±20mm) and its rate of change limited (not exceeding 50mm / s), the output is sent to the flight controller's position control inner loop via the MAVLink protocol. The flight controller superimposes Δn onto the current desired position point, thereby driving the UAV to slowly approach or move away from the curtain wall, causing the compression of the elastic mechanism to return to the target value.

[0090] (4) Wall adhesion operation permission determination. When || enters the target window (e.g., ||≤2cm or ||≤5N) and remains stable for a duration of not less than 2 seconds, the collaborative control system 8 determines that the current normal adhesion has been stably established and sends an operation permission signal to the scrubbing head controller. Only after receiving this signal can the scrubbing head controller start the roller brush motor and walking drive to begin autonomous scrubbing. If || exceeds the safety window during the operation (e.g., ||>10cm or ||>15N), the scrubbing head controller immediately suspends high-speed movement within the plane and prioritizes waiting for the UAV to re-establish normal stable adhesion.

[0091] (5) Separation of master and slave responsibilities. After entering the wall-hugging operation state, the scrubbing head assembly 3 moves autonomously within the curtain wall plane according to its own path planning (e.g., a pre-loaded grid map or real-time visual navigation). The UAV flight platform 1 no longer directly tows the scrubbing head assembly 3, but only performs passive position following. Its following target is not to drag the scrubbing head assembly 3, but to maintain the operation geometry (i.e., the working arm does not have an excessively large deflection angle) and the stability of the normal force chain.

[0092] (6) In-plane tracking calculation. The collaborative control system 8 calculates the slow tracking amount of the UAV in the curtain wall plane based on the in-plane deviation Δr of the scrubbing head assembly 3 relative to the UAV (obtained by vision-IMU fusion, unit: mm) and the angular displacement θ of the working arm relative to the center position (unit: rad). For example, the in-plane tracking calculation formula is: Where: is the slow following distance of the UAV within the curtain wall plane (m); is the in-plane deviation of the scrubbing head assembly 3 relative to the UAV (m); is the angular displacement of the working arm relative to the center position (rad); is the relative position following gain; is the working arm attitude recovery gain, preferably (dimensionless). The in-plane following gain should be much smaller than the walking control gain of the scrubbing head assembly 3 itself (for example, the maximum walking speed of the scrubbing head assembly 3 is 0.3m / s, while the UAV following speed is limited to within 0.05m / s), ensuring that the scrubbing head assembly 3 is always the dominant end of the movement within the wall, and the UAV is only used to prevent excessive swaying of the working arm and tilting of the force chain.

[0093] In this embodiment, the detection of in-plane deviation employs a monocular vision and IMU fusion scheme. Specifically, a monocular camera is mounted on the UAV, and a QR code marker and IMU are mounted on the cleaning head assembly 3. The monocular camera identifies the QR code and, based on its known dimensions, calculates the relative pose of the cleaning head assembly 3 relative to the camera. Then, according to the extrinsic parameter relationship between the camera coordinate system and the UAV system, and the installation pose relationship between the QR code and the cleaning head assembly 3, the relative pose is converted into the relative pose of the cleaning head assembly 3 relative to the UAV system, and further projected onto the curtain wall plane coordinate system to obtain the in-plane deviation. The IMU on the cleaning head assembly 3 provides attitude change and short-term motion prediction information, continuously predicts the relative pose during visual measurement intervals, and performs fusion correction during visual updates. The fusion algorithm can employ complementary filtering, extended Kalman filtering, or error state Kalman filtering to improve the stability and continuity of deviation estimation under conditions of vibration, short-term occlusion, and illumination changes.

[0094] (7) Abnormal handling. When the system detects that the continuous over-limit exceeds 3 seconds, is greater than 0.5m, θ is greater than 30°, contact is lost, an obstacle crossing request is received, or wind disturbance exceeds the limit, the system will first suspend the current high-speed operation in the plane and switch to the normal pressure recovery or coordinated obstacle crossing / safe evacuation process.

[0095] The aforementioned constant pressure closed-loop and position following control transforms traditional hard-top operation of UAVs into compliant constant pressure operation, significantly reducing the requirements for near-wall positioning accuracy of UAVs, while enabling the scrubbing head assembly 3 to independently and flexibly complete complex paths.

[0096] 3.3 Dynamic center of gravity adaptive balance To further reduce the pitch trim burden on the UAV caused by resisting the gravity of the front arm and the cleaning head assembly 3, and to reduce the frictional force required for the cleaning head assembly 3 to stably adhere to the glass surface, this invention provides a dynamically adjustable counterweight assembly 10 on the rear side. This section describes in detail how the position of the counterweight assembly 10 is adjusted in real time using the change in the front arm reflected by the compression displacement of the elastic redundancy compensation mechanism 6, so that the system maintains a dynamic zero torque or target equilibrium torque state relative to the UAV attachment point (or hinge point).

[0097] Let the equivalent gravity formed by the front scrubbing head assembly 3 and the forward working arm be (including the weight of the scrubbing head assembly 3 itself, the weight of the working arm, and accessories such as pipelines), the equivalent gravity of the counterweight assembly 10 be , the compression displacement of the elastic redundancy compensation mechanism 6 be x, the effective lever arm at the front end be , and the lever arm at the rear end corresponding to the current position of the rear counterweight be . For example, the front and rear torques can be expressed as: Where: is the torque generated by the equivalent gravity at the front end (N·m); is the equivalent gravity at the front end (N); is the effective lever arm at the front end (m), which is a function of the compressive displacement; is the torque generated by the rear counterweight (N·m); is the equivalent gravity of the rear counterweight (N); is the lever arm at the rear end (m), which is a function of the position of the counterweight.

[0098] The system control objective is to maintain the balance tolerance ΔM (e.g., ±5 N·m) within the range of either ΔM or the difference between ΔM and ΔM.

[0099] The specific control steps are as follows: (1) Displacement acquisition. The compression displacement x (unit: m) of the elastic redundancy compensation mechanism 6 and the current position r of the counterweight component 10 (measured from the front end of the support rod, unit: m) are acquired in real time. At the same time, the pitch trim amount (from the attitude loop output of the flight control), pitch angular velocity or PWM duty cycle of the rear rotor of the UAV flight platform 1 can be optionally acquired as secondary correction quantities.

[0100] (2) Calculation of eccentric load moment. Based on the pre-calibrated geometric relationship, a mapping table between the compression displacement x and the effective lever arm at the front end is established. In this embodiment, through actual measurement calibration, the following values ​​can be obtained: when x=0 (fully extended), =3.5m; when x=0.4m (working compression point), =3.1m; when x=0.8m (fully compressed), =2.7m. Assuming =120N (approximately 12kg equivalent weight), then =120×3.1=372N·m. Note that the weight of the working arm has been included, but the moment at the hinge point at the arm root also needs to consider the weight distribution of the arm body. For actual calculation, a more accurate multi-body model or experimental calibration can be used.

[0101] (3) Calculation of target counterweight position. Based on the current situation, the target position of the rear counterweight that satisfies the target balance condition is calculated. From the balance equation, we obtain... 。 Then, based on the geometric relationship of the rear counterweight support rod, the solution can be obtained. If a simplified incremental form is used, it can also be written as: Where is the adjustment amount of the rear counterweight position (m), and is the torque compensation gain (e.g., 0.005m / (N·m)). The integral term can eliminate steady-state error. The essence of this notation is to establish a one-to-one linkage between the front compression displacement and the rear counterweight position.

[0102] (4) Counterweight Execution Control. The collaborative control system 8 drives the counterweight servo motor, causing the counterweight block to move along the guide rail towards the target position r* at a speed not exceeding 0.1 m / s. During the movement, an acceleration upper limit (0.2 m / s²) and an end-point buffer (deceleration 0.02 m before reaching the target position) are set. The position closed loop adopts PID control, with a steady-state error of less than ±1 cm. If the system adopts a multi-level adjustment structure (e.g., only 2~3 discrete positions), the corresponding level is selected according to the range where r* is located.

[0103] (5) Secondary correction. During the wall-hugging operation, the collaborative control system 8 simultaneously monitors the pitch trim residual of the flight control (i.e., the difference between the desired pitch angle and the actual pitch angle). If the residual exceeds ±2° and lasts for more than 1 second, a small fine adjustment δr (e.g., δr = 0.01 m / °) is added to r*. This avoids balance deviations caused by load changes, wear, or measurement errors when relying solely on the geometric model.

[0104] (6) Mode switching. During the takeoff and transport phase, the counterweight assembly 10 can be maintained in the flight trim position (e.g., r=0.8m, so that the center of gravity is close to the center of the UAV). When the system enters the wall-hugging operation phase and the compression amount x is stable within the range of 30~50cm, the dynamic center of gravity adaptive balance module starts to work and adjusts r in real time according to x. After the withdrawal is completed, the system returns the counterweight assembly 10 to the flight trim position. If a continuous servo drive mechanism is not configured, a two-stage switching between takeoff and operation modes can also be used: for example, when x>20cm, the counterweight automatically moves to the operation position; when x<10cm, the counterweight returns to the takeoff position.

[0105] (7) Abnormal Protection. When the displacement sensor fails, the counterweight actuator malfunctions (such as stall or overcurrent), the position feedback encoder malfunctions, or the pitch residual abnormally increases (>5°), the system stops further adjustment and prioritizes locking the counterweight assembly 10 at the current position (or the preset safe position). It then temporarily undertakes the additional trim task through the pitch angle limiter and attitude loop integral limiter of the flight control. At the same time, a counterweight fault alarm is sent to the ground station.

[0106] Through dynamic center of gravity adaptive balance, the present invention can automatically maintain the torque balance of the whole machine during the wall-attaching operation, which significantly reduces the extra power consumption of the drone to resist the off-center load torque. At the same time, it also allows the cleaning head assembly 3 to be stably attached to the glass surface with only a small amount of friction (because the gravity of the cleaning head assembly 3 has been effectively balanced by the rear counterweight).

[0107] 4. Sway suppression While the articulated structure effectively decouples the fuselage from the terminal operations, the large-inertia boom suspended below will exhibit pendulum-like oscillations during takeoff, cruise, yaw, and gust disturbances after the rigid constraints are removed. The variable damping / variable constraint control described earlier provides high-damping vibration suppression during flight, but during evacuation, if the system remains in a low-damping, compliant state and retreats directly, it will cause the boom to fall and oscillate, the scrubbing head assembly 3 to collide with the wall, or the flight platform to become unstable. Furthermore, a reasonable obstacle-crossing strategy is required when encountering curtain wall obstacles during wall-hugging operations. This section focuses on the evacuation safety interlock control and the hierarchical cooperative obstacle-crossing algorithm.

[0108] 4.1 Evacuation safety interlock control This embodiment addresses the issues of long-arm swaying, scrubbing head assembly 3 hitting the wall, or flight platform instability caused by the system retracting directly while still in a low-damping compliant state after scrubbing is completed, abnormally interrupted, or during block switching. The evacuation safety interlock control is not a single retraction command, but a set of interlocking conditions and action sequences that must be met sequentially.

[0109] The coordinated control system 8 is equipped with the following interlocking indicators: : Task completion or interruption trigger flag; : Cleaning head assembly 3 stops moving confirmation mark; : Marker of completion in the center; Damping recovery confirmation indicator; : Normal compression release to safe range indicator.

[0110] The system only releases the evacuation permission to the flight controller when the conditions for evacuation are met.

[0111] The specific evacuation process includes: (1) Evacuation Trigger. When any of the following situations occur: the scrubbing head assembly 3 reaches the boundary of the target block, the operation task is completed, the operator manually interrupts the operation, abnormal pressure is detected (F>80N or F<5N for more than 2 seconds), abnormal compression (x>75cm or x<5cm), abnormal UAV attitude (roll angle>20°), wind disturbance exceeds the limit (A>8° and f>2Hz), abnormal damping state (actual damping deviates from the command by more than 50%), or communication timeout (>500ms), the system immediately switches from the wall-hugging operation state to the evacuation preparation state and sets the position.

[0112] (2) Stop the active movement of the front end. The collaborative control system 8 sends an emergency stop command to the scrubbing head controller, requiring it to stop all walking motors and roller brush motors within 0.5 seconds and maintain the current normal pressure within the safe working window (maintained by the UAV constant pressure closed loop). The scrubbing head controller feeds back the speed detection value, and sets the position when the speed of all motors drops below the threshold (e.g., <0.01m / s) and remains below it for 0.5 seconds.

[0113] (3) Centering. Without releasing the normal force chain (i.e., maintaining the elastic compression within the range of 30-50cm), the UAV flight platform 1 finely adjusts its in-plane position and attitude, bringing the angular displacement |θ| of the forward working arm back to within the preset centering tolerance (e.g., =3°), and simultaneously bringing the planar deviation || of the cleaning head assembly 3 relative to the UAV back to within the preset tolerance (e.g., =0.1m). During this process, the return spring of the end universal joint and the elastic return unit at the arm root work together to assist the working arm in naturally returning to center. The centering detection unit continuously monitors and only sets the position when |θ|≤, ||≤, and the duration is not less than =2 seconds.

[0114] (4) Damping Recovery. After alignment, the coordinated control system 8 sends a damping recovery command to the electrically controlled articulated damping connection assembly 4, gradually increasing its damping from the low-damping state of wall-hugging operation (c≈5N·s / rad) to the high-damping state required for flight (c≥150N·s / rad). If a clutch-type structure is used, the clutch engages; if an adjustable damper is used, the damping coefficient increases according to a ramp function (slope 50N·s / rad / s). The damping state feedback sensor reads the actual damping value in real time, and is set only when the actual damping value reaches the preset threshold (c≥120N·s / rad) and remains so for 0.5 seconds.

[0115] (5) Compression Release. After the damping is restored, the UAV flight platform 1 slowly retreats along the normal direction of the curtain wall at a speed not exceeding 5 cm / s. At this time, the compression displacement x of the elastic redundant compensation mechanism 6 gradually decreases, and the contact pressure F also decreases accordingly. The control system monitors x and F in real time. When x drops to below the safe release range of 10 cm or F drops to below 10 N and remains so for 0.5 seconds, the system is set.

[0116] (6) Withdrawal Permission. When all three conditions are true, the Cooperative Control System 8 sends an withdrawal permission flag to the Flight Controller. Only after receiving this flag can the Flight Controller execute further withdrawal, detachment from the wall, and transition to transport flight maneuvers. If any flag is not met, the Flight Controller layer will block the withdrawal command or only allow hovering / fine-tuning, and will not allow direct detachment from the wall.

[0117] (7) Abnormal Branch. If the centering process is not completed within 30 seconds, or if B4 is not set within 5 seconds after the damping recovery command is issued, or if the pressure release fails to reach the safe zone within 10 seconds, or if the attitude remains abnormal during this period, the system enters the abnormal evacuation branch. This branch prioritizes maintaining a high-damped state and a low-speed safe attitude (maximum evacuation speed 2cm / s), and forced evacuation under low-damped conditions is prohibited. At the same time, the system sends an emergency alarm to the ground station via the data transmission link, requesting manual takeover or activation of a higher-level protection mode (such as automatic descent to the roof platform).

[0118] Through the above interlocking logic, the evacuation process is strictly limited to a rigid sequence of stopping the front-end movement → centering → restoring high damping → confirming damping → slow release of pressure attachment → allowing retraction, which fundamentally eliminates the dangerous operation of directly detaching from the curtain wall in a low-damping compliant state.

[0119] 4.2 Hierarchical Cooperative Obstacle Crossing Algorithm This embodiment addresses the obstacle clearance issue when encountering various wall obstacles such as protrusions, steps, and frames on the working surface (curtain walls may have seams, protrusions, moldings, partial borders, or other obstacles). Based on the obstacle characteristics, the system automatically delineates the boundaries of responsibility between the autonomous obstacle clearance of the scrubbing head assembly 3 and the collaborative obstacle clearance by the UAV flight platform 1. This avoids increasing the flight control burden due to the UAV handling all obstacles and also avoids over-reliance on the scrubbing head assembly 3's own capabilities, which could lead to jamming or detachment.

[0120] Let the characteristics of the obstacle ahead be: obstacle height (unit: cm), obstacle width, and edge shape (sharp or rounded). The current normal pressure is x or F, and the current speed of the scrubbing head assembly 3 is [value missing]. The collaborative control system 8 executes the following steps during operation: (1) Obstacle Detection. The laser rangefinder installed at the leading edge of the scrubbing head assembly 3 scans the area in front at a frequency of 10Hz. When a sudden decrease in distance is detected (e.g., from the normal spacing of 0~2cm to greater than 5cm, or a negative value indicating a protrusion), combined with a sudden increase in motor current (the walking motor current exceeds the normal value by 150%), an obstacle is determined to exist. The system immediately reduces the speed of the scrubbing head assembly 3 to below 0.1m / s and enters the obstacle recognition process.

[0121] (2) Obstacle Classification. The obstacle level is determined based on the current compression margin. A first preset threshold H1 = 5cm is set. If ≤H1 and the current compression amount x is within the allowable obstacle crossing window (e.g., x is between 20~60cm, meaning the spring still has sufficient compression margin), it is determined to be a Class I obstacle (small obstacle); if >H1, or although it does not exceed H1 but fails to autonomously cross the obstacle within the time limit, it is determined to be a Class II obstacle (large obstacle requiring UAV cooperation). At the same time, if the edge shape is sharp (such as a right angle of a metal frame), even if <5cm, it can be upgraded to Class II according to the strategy to avoid scratching the tracks.

[0122] (3) Autonomous obstacle crossing for the first type of obstacle. For the first type of obstacle, the cleaning head assembly 3 does not request large movements from the UAV, but instead enters the autonomous obstacle crossing mode: a. Reduce your walking speed to the obstacle-crossing speed v_h1=0.05m / s; b. Maintain normal pressure within the allowable fluctuation range (through constant pressure closed-loop automatic adjustment of the UAV, allowing fluctuations of ±10N). c. It relies on the climbing ability of its tracks (maximum obstacle clearance height 5cm) and the flexibility of its chassis to complete the crossing. The front end of the scrubbing head assembly 3 is designed with a guide ramp, which can convert the protrusion into lifting force; d. After successfully overcoming the obstacle, confirm the distance with the sensor (the distance returns to normal and the motor current drops back), and restore the normal speed (0.2~0.3m / s) and operating status.

[0123] Throughout the process, the UAV flight platform 1 only maintains constant pressure closed loop and low gain position following, and does not actively implement wall dragging.

[0124] (4) Autonomous obstacle crossing failure upgrade. If the obstacle crossing is not completed within the first preset time T1=5 seconds (i.e., the distance sensor still shows an obstacle, or the motor current continues to be higher than 200% of the rated value), or abnormalities such as a sudden increase in pressure exceeding 80N, abnormal drop in compression (x<10cm, indicating that the scrubbing head assembly 3 is lifted off the wall), or the attitude angle of the scrubbing head assembly 3 exceeds the limit, then the first type of obstacle crossing failure is determined, and the process is automatically upgraded to the second type of obstacle handling process.

[0125] (5) Collaborative obstacle crossing for the second type of obstacle. For the second type of obstacle, the scrubbing head controller immediately suspends active walking and sends a collaborative obstacle crossing request to the collaborative control system 8 via the CAN bus. The collaborative control system 8 first switches the electrically controlled articulated damping connection component 4 from the wall-hugging low-damping state (c≈5N·s / rad) to the intermediate damping state (c≈50N·s / rad) required for assisting obstacle crossing, in order to improve the attitude stability of the UAV during large movements. Subsequently, the UAV flight platform 1 executes the following sequence of actions: Briefly increase height: The drone moves back about 10-20cm along the normal direction (i.e., reduces the elastic compression to 10cm), which reduces the pressure between the scrubbing head assembly 3 and the curtain wall, making it easier to lift; Vertical lifting: The drone slowly rises (0.1m / s) while making slight forward adjustments, allowing the scrubbing head assembly 3 to slide along the edge of the obstacle until it is completely cleared; Reset: After passing through, the drone approaches the curtain wall normally again, repeating the pressing and contact judgment process, so that the compression of the elastic mechanism returns to the target value of 40cm.

[0126] During cooperative obstacle crossing, the flight control system still adheres to the low yaw rate limit (≤10° / s) to prevent large inertia yaw from causing instability.

[0127] (6) Re-establishing the wall-hugging state after overcoming the obstacle. After the second type of obstacle is overcome, the UAV does not immediately resume high-speed operation, but re-executes the process of approaching the wall, compressing and establishing, contact confirmation and damping reduction. After x or F returns to the target working window (x=35~45cm or F=45~55N) and stabilizes for 2 seconds, the electronically controlled articulated damping connection component 4 switches back to the low-damping state of wall-hugging operation, and the wiping head component 3 resumes autonomous walking and cleaning.

[0128] (7) Safety Constraints. Throughout the obstacle crossing process, the flight control system continuously monitors the following safety conditions: yaw rate <10° / s, UAV roll angle <15°, pitch angle <20°, and elastic compression not exceeding the range of 0~80cm. If any condition exceeds the limit, the current obstacle crossing action will be terminated immediately and the system will switch to safe evacuation logic.

[0129] Through a hierarchical collaborative obstacle-crossing algorithm, this invention can handle most common obstacles on curtain walls, fully leveraging the obstacle-crossing capability of the cleaning head assembly 3's own tracks while retaining the flexibility of UAVs in collaboratively handling large obstacles, significantly improving the system's environmental adaptability.

[0130] 4.3 Low Yaw Safety Control Given that the robot proposed in this invention has a long front arm (3.5m) and a rear counterweight (15~20kg), the rotational inertia of the entire machine about the yaw axis is much greater than that of ordinary multi-rotor drones. If the drone yaws at a high angular velocity, the long arm will generate huge lateral swing due to centrifugal force, which may not only damage the ball joint connection mechanism, but also cause the scrubbing head assembly 3 to be thrown out and hit the curtain wall or explode. Therefore, the collaborative control system 8 has a built-in low yaw safety control module.

[0131] Specific measures include: Flight Phases: During takeoff, transport, approach to the curtain wall, and evacuation, the yaw rate of the flight control system is limited to no more than 15° / s, and the acceleration is limited to no more than 5° / s². Yaw commands must be smoothed by the ramp generator.

[0132] During the wall-hugging operation phase: Although the ball joint is in a low-damping state at this time, the yaw rate is more strictly limited, not exceeding 5° / s. This is because any yaw will cause the long arm to swing laterally, and even with low damping, it will generate inertial force that is transmitted to the scrubbing head assembly 3, which may cause track slippage or uneven scraping.

[0133] Sharp turns are prohibited: When the flight speed is greater than 2 m / s, it is prohibited to perform a combination of yaw and lateral movement at the same time to prevent the generation of excessive Coriolis force.

[0134] Near-wall safety turning strategy: When needing to change course when close to the curtain wall (distance <1m), the system prioritizes a three-stage maneuver: first, retreating along the normal to a safe distance (≥2m), then yawing in open space, and finally approaching the curtain wall again. Although this strategy takes slightly longer, it completely avoids the risk of the long arm sweeping against the wall.

[0135] The cooperative control system 8 continuously monitors the yaw rate. Once it detects that the yaw rate exceeds the limit, it immediately and automatically reduces the yaw command and sends a speed saturation warning to the flight controller. If passive yaw exceeds the limit due to gusts, the system will automatically increase the ball joint damping and issue an alarm, and perform an emergency evacuation if necessary.

[0136] 5. Complete control method and process Based on the above modules, this embodiment provides a complete control method for an airborne curtain wall cleaning robot with elastic redundancy compensation. It should be noted that the specific values ​​involved in this embodiment (such as compression threshold, pressure threshold, judgment time, obstacle height, etc.) are preferred examples and do not constitute a limitation on the scope of protection of this invention. Those skilled in the art can make adaptive adjustments according to actual working conditions. This method follows the main line of safe distance—attitude decoupling—constant pressure wall adhesion—oscillation suppression, and includes the following steps: Step S1: Pre-flight initialization and connection status check Perform power-on self-tests on the UAV flight control system, cleaning head controller, ball joint connection mechanism actuator, rear counterweight adjustment actuator, and various sensors. Confirm that the electronically controlled ball joint connection mechanism 5 is in the first connection state (high damping) and that the elastic return unit is working normally; Confirm that the compression displacement sensor, pressure sensor, vision recognition unit, IMU, angle sensor, centering detection unit, and relative pose calculation link are working properly; The center of gravity model and control parameters are initialized based on the current mass of the front-end wiping head assembly 3 (input via a weighing sensor or manually), the initial position of the rear counterweight, the zero-position parameters of the elastic redundancy compensation mechanism 6, and the system geometric parameters.

[0137] Step S2: Vehicle Approach (Safe Distance Phase) The drone, carrying the working arm and cleaning head assembly 3, flies to the starting point of the target curtain wall operation, with a flight speed not exceeding 2m / s and a yaw rate not exceeding 10° / s. During this stage, the ball joint connection mechanism maintains the first connection state (high damping), and the damping coefficient is set to 100~150 N·s / rad; The flight control system adopts a low-speed stable approach strategy and prioritizes the headwind heading hold mode to avoid crosswinds causing the long arm to wobble. The drone hovers at a predetermined safe distance (usually 2 meters) in front of the starting point.

[0138] Step S3: Compression and Contact Judgment (Preparation for Constant Pressure Adhesion) The drone is slowly approaching the curtain wall along the normal direction at a speed of 0.1 m / s; The scrubbing head assembly 3 first contacts the curtain wall surface, and the elastic redundancy compensation mechanism 6 begins to compress. The control system reads the compression amount x and pressure value F in real time; When x≥35cm or F≥45N is detected and maintained stably for 1 second, it is determined that the wiping head assembly 3 has reliably adhered to the wall.

[0139] Step S4: Connection state switching and pressure attachment closed loop establishment (attitude decoupling) After the reliable wall contact determination is established, the control system issues a constraint reduction command to the ball joint connection mechanism, switching it from the first connection state to the second connection state (low damping), and the damping coefficient gradually decreases to below 5 N·s / rad; Simultaneously, a compression closed-loop control is established with compression amount or pressure as the target quantity, the target compression amount x*=40cm or the target pressure F*=50N, and PID position servo is adopted.

[0140] Step S5: Collaborative scrubbing operation and dynamic balancing (constant pressure wall adhesion and vibration suppression) The scrubbing head assembly 3 starts the roller brush motor (400 rpm) and moves autonomously on the curtain wall surface according to the planned path (a global coverage path generated based on the 3D point cloud model of the building), with a walking speed of 0.2~0.3 m / s; The drone enters position servo follow mode, no longer actively pulling the scrubbing head assembly 3 within the wall surface, but instead, based on the calculated positions of the scrubbing head assembly 3, the angle of the working arm, and θ and ω, it uses low gain ( Kr =0.2, 0.1) Continuously adjust its position to remain behind the wiping head assembly 3; The drone maintains the compression of the elastic redundancy compensation mechanism 6 at around 40cm by fine-tuning its position, thereby maintaining a clamping force of about 50N. The control system estimates the system's center of gravity projection and torque balance state in real time based on the compression amount x, angular displacement θ, angular velocity ω, UAV attitude and the current position of the rear counterweight, and drives the counterweight component 10 to perform electronic control adjustment along the support arm so that the system is continuously in the preset balance range (torque difference between front and rear ≤ ±5N·m). When the obstacle crossing / boundary detection unit detects an obstacle ahead, it processes it according to the hierarchical cooperative obstacle crossing algorithm: if the obstacle height is ≤5cm, the cleaning head assembly 3 uses its own power to directly cross the obstacle; if the obstacle height is >5cm or the autonomous obstacle crossing fails, the cleaning head assembly 3 stops walking independently and sends an obstacle crossing request to the drone. The drone briefly increases its height to help the cleaning head assembly 3 cross the obstacle and then re-executes the pressing action.

[0141] Step S6: Reaching the boundary or triggering an interruption The system will enter evacuation preparation mode if any of the following conditions are met: The wiping head assembly 3 reaches the boundary of the target block (for example, the position coordinates of the wiping head assembly 3 exceed the preset range). The cleaning task is complete (operator issues end command); Abnormal interruptions may occur due to: excessive wind disturbance (body tilt >15°), abnormal pressure (F>80N or F<5N for more than 2 seconds), abnormal attitude (roll angle >25°), communication interruption (>1 second), or emergency stop button being pressed.

[0142] Step S7: Centering, restoring damping and disengaging (suspension of oscillation) The drone first adjusts its position until the drone's central axis, working arm, and cleaning head assembly 3 meet the preset centering conditions (|θ|≤3°, |Δr|≤0.1m), and the working arm tends to the center position under the action of the elastic centering unit; After alignment is completed, the control system sends a constraint recovery command to the ball joint connection mechanism, which increases the damping coefficient to above 120 N·s / rad and re-enters the first connection state. After the damping is restored, the drone slowly retreats along the normal direction of the curtain wall at 0.05m / s, causing the compression displacement of the elastic redundancy compensation mechanism 6 to fall below 10cm or the contact pressure to drop below 10N; The system only allows the UAV to perform a backward horizontal retreat action after the ball joint connection status is confirmed to be valid (damping > 100 N·s / rad) and the pressure has been released to the safe release range; if the ball joint connection status is not restored to the preset value or the alignment is not completed, the UAV's backward retreat action is prohibited.

[0143] Step S8: Evacuation and Next Work Cycle The drone pulls the working arm and the scrubbing head assembly 3, which are in a controlled compliant articulated state (high damping), away from the curtain wall at a speed not exceeding 1m / s. Fly to the starting point of the next block (multiple work blocks can be planned in advance); Repeat steps S2 to S8 to complete the next cycle.

[0144] In another embodiment, to simplify the structure and reduce costs, a fixed damper combined with a mechanical clutch mechanism can be used instead of a continuously adjustable damper. In this case, the first connection state corresponds to clutch engagement, providing fixed high damping (e.g., 150 N·s / rad); the second connection state corresponds to clutch disengagement, providing near-undamped damping. The elastic return-to-center unit is still retained. The counterweight assembly 10 can be manually adjusted in two positions (flight and work positions) instead of servo continuous adjustment, but the dynamic center-of-gravity adaptive balancing function will be simplified to on / off control: when the compression x > 20 cm, the counterweight moves to the work position; when x < 10 cm, the counterweight returns to the flight position. The preset threshold for graded obstacle crossing can be adjusted to 3 cm or 8 cm based on actual testing. The elastic element in the elastic redundancy compensation mechanism 6 can also use a gas spring instead of a helical spring to provide smoother force-displacement characteristics. These variations do not depart from the core inventive concept of this invention and still fall within the protection scope of this invention.

[0145] The length, mass, force, stroke, threshold, and time parameters provided in this invention (e.g., forward working arm length 3.5m, scrubbing head assembly 3 mass 5-10kg, rear counterweight 15-20kg, total stroke of the elastic mechanism 80cm, working compression 40cm, clamping force 50N, etc.) are only preferred embodiments, used to illustrate the technical effects achievable by this invention. In practical applications, these parameters can be appropriately adjusted according to different curtain wall types (glass, aluminum panel, stone), building height, climate conditions, and the load capacity of the UAV platform. For example: For larger curtain wall cleaning tasks, an octagonal drone with a payload of over 50kg can be used, with the working arm length extended to 5 meters, the cleaning head assembly 3 weight increased to 15kg, the rear counterweight correspondingly increased to 30kg, the elastic mechanism stroke extended to 120cm, and the target clamping force increased to 80N.

[0146] For small buildings or curved curtain walls, the boom can be shortened to 2 meters, reducing the overall weight of the machine and improving maneuverability.

[0147] The elastic element is not limited to helical springs; gas springs, rubber springs, or hydraulic accumulators can also be used, as long as they can provide stable force-displacement characteristics.

[0148] Damping adjustment methods are not limited to friction plates or magnetorheological fluids; new technologies such as eddy current dampers and piezoelectric ceramic-driven variable damping can also be used.

[0149] All of these variations should fall within the scope of protection of this invention.

[0150] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0151] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. An airborne contact robot with elastic redundancy compensation, characterized in that, include: Unmanned aerial vehicle (UAV) flight platform; The first end of the working arm assembly is hinged to the UAV flight platform via a connection mechanism that allows the working arm assembly to deflect attitude relative to the UAV flight platform. The working end actuator is disposed at the second end of the working arm assembly and includes a moving module for autonomous movement on the working surface; An elastic redundancy compensation mechanism is disposed between the second end of the working arm assembly and the working end actuator to provide buffer stroke and adhesion force along the normal direction of the working surface; The collaborative control system is communicatively connected to the flight control system of the UAV flight platform and the operating end actuator, respectively. The collaborative control system is used to: when the actuator at the working end is in contact with the working surface, control the UAV flight platform to provide normal thrust to the actuator at the working end, and at the same time control the UAV flight platform to move with the actuator at the working end.

2. The airborne contact robot with elastic redundancy compensation according to claim 1, characterized in that, The system also includes a constraint adjustment component, which works in conjunction with the application of adjustable constraints to the swing of the working arm assembly relative to the UAV flight platform. Based on different constraints, the UAV flight platform and the working arm assembly include a first connection state and a second connection state. During the flight transport phase, it enters the first connection state to suppress the swaying of the working arm assembly; During the wall-hugging operation phase, once it is determined that the working end actuator has reliably adhered to the wall, the connection state is switched from the first connection state to the second connection state, thereby releasing the sway suppression of the working arm assembly and reducing the interference of the UAV flight platform attitude correction on the working end actuator.

3. The airborne contact robot with elastic redundancy compensation according to claim 2, characterized in that, The collaborative control system is also used for: During the wall-hugging operation phase, a normal correction command is generated based on at least one contact state quantity of the elastic redundancy compensation mechanism and / or the working end actuator, and sent to the flight control system of the UAV flight platform to fine-tune the position of the UAV flight platform along the normal of the working surface in a closed-loop manner, so that the compression or pressure is maintained at the target value. The positional deviation of the working end actuator relative to the UAV flight platform and / or the angular displacement of the working arm assembly relative to the center position are obtained, and a plane-following command is generated to control the UAV flight platform to passively follow within the working plane.

4. The airborne contact robot with elastic redundancy compensation according to claim 2, characterized in that, The coordinated control system is also used to execute evacuation safety interlock control, including: When the operation is completed or interrupted, the drone flight platform is controlled to adjust its position so that the working arm assembly meets the preset centering conditions. After the preset alignment condition is met, the connection is restored to the first connection state; After confirming the restoration to the first connection state, control the UAV flight platform to retreat and release the compression or pressure of the elastic redundancy compensation mechanism; The drone flight platform is only permitted to perform an evacuation maneuver after the compression or pressure has been released to the safe release range.

5. The airborne contact robot with elastic redundancy compensation according to claim 2, characterized in that, The collaborative control system is also used for: The angular displacement and angular velocity of the working arm assembly are acquired in real time. When the product of the angular displacement and the angular velocity is greater than zero, the system enters the first connection state. When the product of the angular displacement and the angular velocity is less than zero, the system enters the second connection state.

6. The airborne contact robot with elastic redundancy compensation according to claim 1, characterized in that, Also includes: The counterweight assembly is configured to adjust the torque balance of the system to compensate for the off-center load torque generated by the boom assembly and the end effector. The collaborative control system is also used for: Obtain the real-time compression amount of the elastic redundancy compensation mechanism; The off-center load moment is calculated based on the real-time compression amount; Based on the eccentric load moment, the counterweight assembly is driven to adjust its position to balance the eccentric load moment.

7. The airborne contact robot with elastic redundancy compensation according to claim 1, characterized in that, The collaborative control system is also used for: Obtain the feature values ​​of the obstacle in front of the working end actuator; When the obstacle feature quantity is less than or equal to a preset threshold, the operating end actuator is controlled to start the autonomous obstacle-crossing mode; When the obstacle feature value is greater than a preset threshold, or when autonomous obstacle crossing fails, the operator controls the working end actuator to pause walking and controls the UAV flight platform to perform posture adjustment actions to assist in overcoming obstacles.

8. The airborne contact robot with elastic redundancy compensation according to claim 1, characterized in that, A pneumatic auxiliary device is also provided at the second end of the working arm assembly and / or at the working end actuator. The pneumatic auxiliary device is used to output pneumatic force to assist in adjusting the state of the end of the working arm assembly.

9. The airborne contact robot with elastic redundancy compensation according to claim 1, characterized in that, The working arm assembly is a length-adjustable structure, including an arm segment that can move relative to the working arm assembly along its axial direction, so that the overall length of the working arm assembly can be adjusted within a preset range.

10. The airborne contact robot with elastic redundancy compensation according to claim 1, characterized in that, The collaborative control system is also used to: limit the yaw rate to within a preset upper limit under all working conditions, and adopt a lower yaw rate limit than that used in the flight transport phase during the wall-hugging operation phase; when it is necessary to change the heading in the wall-hugging state, control the UAV flight platform to sequentially perform the following actions: retreating along the normal direction of the work surface to a preset safe distance, yawing to the target heading, and reapproaching the work surface.

11. A control method for an airborne contact robot with elastic redundancy compensation, applied to the robot as described in any one of claims 1-10, characterized in that, Includes the following steps: Step S1: During takeoff and transport, enter the first connection state and suppress the swing of the working arm assembly; Step S2: Approaching the work surface stage, control the UAV flight platform to approach the work surface in the normal direction until the work end actuator contacts the work surface and causes the elastic redundancy compensation mechanism to compress; Step S3: Contact determination stage. When the compression amount or contact pressure of the elastic redundancy compensation mechanism is detected to reach a preset threshold and stabilize, it is determined that the actuator at the working end has reliably adhered to the wall. Step S4: Switching and operation phase, switching from the first connection state to the second connection state, and establishing pressure-adhesion closed-loop control to maintain the compression amount or pressure of the elastic redundancy compensation mechanism at the target value, while controlling the operation end actuator to move autonomously on the operation surface to perform contact operation.

12. The control method for an airborne contact robot with elastic redundancy compensation according to claim 11, characterized in that, It also includes evacuation steps: When the operation is completed or interrupted, the drone flight platform is controlled to adjust its position so that the working arm assembly meets the preset centering conditions. After the preset alignment condition is met, the connection is restored to the first connection state; After confirming that the connection has been restored to the first connection state, control the UAV flight platform to retreat and release the compression or pressure of the elastic redundancy compensation mechanism; The UAV flight platform is only allowed to perform an evacuation action after the compression or pressure of the elastic redundancy compensation mechanism has been released to the safe release range.

13. The control method for an airborne contact robot with elastic redundancy compensation according to claim 11, characterized in that, The pressure-adhesion closed-loop control includes: Obtain the real-time compression amount or real-time contact pressure of the elastic redundancy compensation mechanism; Based on the difference between the real-time compression amount and the target compression amount, or the difference between the real-time contact pressure and the target contact pressure, a normal correction command is generated. The normal correction command is sent to the flight control system of the UAV flight platform to fine-tune the position of the UAV flight platform along the normal of the working surface, so that the compression or pressure of the elastic redundancy compensation mechanism is maintained near the target value.

14. The control method for an airborne contact robot with elastic redundancy compensation according to claim 11, characterized in that, The switching between the first connection state and the second connection state includes: acquiring the angular displacement and angular velocity of the working arm assembly in real time; when the product of the angular displacement and angular velocity is greater than zero, entering the first connection state to dissipate the kinetic energy of the working arm with high damping; when the product of the angular displacement and angular velocity is less than zero, entering the second connection state to allow the working arm to quickly return to center under the action of restoring force with low damping; and maintaining the current connection state when both the angular displacement and angular velocity are within the preset dead zone range.

15. The control method for an airborne contact robot with elastic redundancy compensation according to claim 11, characterized in that, It also includes a dynamic counterweight balancing step: real-time acquisition of the compression displacement of the elastic redundancy compensation mechanism; calculation of the front equivalent force arm and estimation of the off-center load torque based on the compression displacement and the pre-calibrated geometric mapping relationship; and driving the counterweight assembly to adjust its position along the guide rail based on the off-center load torque, so that the difference between the front and rear torques is maintained within the preset balance tolerance range.

16. The control method for an airborne contact robot with elastic redundancy compensation according to claim 11, characterized in that, It also includes a graded obstacle-crossing step: acquiring the obstacle feature quantities in front of the working end actuator; When the obstacle feature quantity is not greater than a preset first threshold, the operating end actuator is controlled to autonomously cross the obstacle at the obstacle crossing speed, and the UAV flight platform maintains a constant pressure closed loop and does not perform large movements; when the obstacle feature quantity is greater than the first threshold, or the autonomous obstacle crossing is not completed within a preset time, the operating end actuator is controlled to pause walking, and the UAV flight platform is controlled to first retreat a preset distance along the normal direction, and then vertically lift, so that the operating end actuator crosses the obstacle and then re-executes the pressing and contact determination process.

17. The control method for an airborne contact robot with elastic redundancy compensation according to claim 11, characterized in that, It also includes low yaw safety control steps: under all working conditions, the yaw rate is limited to not exceeding the preset upper limit, and a lower yaw rate limit is adopted during the wall-hugging operation phase; when it is necessary to change the course in the wall-hugging state, a three-stage maneuver is performed in sequence: retreating along the normal of the working surface to the preset safe distance, yawing to the target course, and reapproaching the working surface.

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