Flight-wall climbing dual-mode conversion unmanned aerial vehicle and motion control method thereof

Abstract

The invention provides a flight-wall climbing dual-mode conversion unmanned aerial vehicle and a motion control method thereof, and relates to the technical field of aircrafts, the unmanned aerial vehicle comprises a rack, the top of which is provided with a laser radar; an adsorption mechanism; each wall surface crawling mechanism comprises a fixed bracket, a walking wheel, a rotor wing, a first motor and a second motor; a plurality of mode conversion mechanisms, wherein each mode conversion mechanism is connected with one wall surface crawling mechanism; the controller is used for obtaining target wall surface characteristics through the laser radar, controlling the second motor to drive the rotor wings to rotate to enable the unmanned aerial vehicle to approach the target wall surface, controlling the first steering engine and the second steering engine to rotate to adjust the attitude of the unmanned aerial vehicle, and adjusting the air pressure in the adsorption cavity through the vacuum pump to enable the adsorption cavity to be adsorbed to the target wall surface. And the first motor is controlled to drive the walking wheel to move on the target wall surface. The unmanned aerial vehicle has the beneficial effects that stable and efficient switching of the unmanned aerial vehicle between a flight mode and a wall climbing mode is achieved, and it is ensured that the unmanned aerial vehicle can be stably transited to the wall surface and keeps stable attachment.

Description

Technical Field

[0001] The present invention relates to the technical field of aircraft, and particularly to a flight-wall climbing dual-mode conversion unmanned aerial vehicle and its motion control method. Background Art

[0002] Currently, multi-rotor unmanned aerial vehicles have been widely used in various task scenarios such as aerial inspections and environmental monitoring due to their flexible control performance and relatively convenient deployment methods. However, due to the inherent constraints of their flight characteristics, multi-rotor unmanned aerial vehicles can only perform tasks in the aerial environment of three-dimensional space, and there are obvious application limitations in special operation scenarios such as vertical walls and complex terrains. Specifically, they cannot operate on these special surfaces and at the same time face the dual technical bottlenecks of insufficient flight performance and wall climbing ability.

[0003] To effectively overcome the above technical problems, some cutting-edge research has proposed innovative solutions, that is, deeply integrating the adsorption force technology with the flight control system of quadrotor unmanned aerial vehicles, aiming to achieve the stable attachment of unmanned aerial vehicles on special surfaces such as walls and at the same time ensure their precise motion control. This technical integration solution provides new ideas and possibilities for expanding the application boundaries of quadrotor unmanned aerial vehicles. However, although the technical solution combining adsorption force and flight control has significant application potential, in practical applications, how to achieve a smooth and efficient switch between the flight mode and the wall climbing mode of the unmanned aerial vehicle, and at the same time ensure that the flight trajectory of the unmanned aerial vehicle remains smooth and avoid collisions during the mode transition process is still a key technical challenge that needs to be overcome urgently. Summary of the Invention

[0004] In view of this, in order to solve the problem of the stable attachment of unmanned aerial vehicles on special surfaces such as walls and at the same time ensure their precise motion control, embodiments of the present invention provide a flight-wall climbing dual-mode conversion unmanned aerial vehicle and its motion control method.

[0005] Embodiments of the present invention provide a flight-wall climbing dual-mode conversion unmanned aerial vehicle, including:

[0006] A frame, on the top of which a lidar is provided;

[0007] An adsorption mechanism, which is arranged at the bottom of the frame. The adsorption mechanism includes an adsorption cavity, a vacuum pump and a pressure sensor. The vacuum pump is connected to the adsorption cavity. A soft skirt is provided at the lower end of the adsorption cavity. The pressure sensor is arranged in the adsorption cavity for detecting the air pressure in the adsorption cavity;

[0008] A plurality of wall-climbing mechanisms, including a fixed bracket, traveling wheels, rotors, a first motor, and a second motor, wherein the traveling wheels are rotatably mounted on the fixed bracket, the first motor is connected to the traveling wheels to drive the traveling wheels to rotate, the rotors are mounted inside the traveling wheels, and the second motor is connected to the rotors to drive the rotors to rotate;

[0009] A plurality of mode conversion mechanisms, each of the mode conversion mechanisms is arranged at intervals around the frame, each mode conversion mechanism is connected to one of the wall-climbing mechanisms, each mode conversion mechanism includes a first servo and a second servo, the first servo is fixedly mounted on the frame and its output end is connected to the second servo, and the output end of the second servo is connected to one of the fixed brackets. The first servo and the second servo are used to drive the wall-climbing mechanism to rotate around two mutually perpendicular rotation axes;

[0010] And a controller, which is respectively connected to the lidar, the vacuum pump, the pressure sensor, the first motor, the second motor, the first servo, and the second servo. The controller is used to obtain the target wall characteristics from the lidar, control the second motor to drive the rotors to rotate so that the drone approaches the target wall, control the first servo and the second servo to rotate to adjust the attitude of the drone, the vacuum pump adjusts the air pressure in the adsorption cavity so that the adsorption cavity adsorbs to the target wall, and control the first motor to drive the traveling wheels to move on the target wall.

[0011] Further, the adsorption cavity includes a fixed plate, a sealing cover, and a movable plate. The fixed plate is fixed to the bottom of the frame. The sealing cover is a multi-layer folded cavity structure. The upper end of the sealing cover is connected to the fixed plate, and the lower end is connected to the movable plate. The soft skirt is connected to the upper end of the movable plate and is arranged around the movable plate for one week.

[0012] Further, the traveling wheel includes a hub, and the hub includes an outer hub, an inner hub, and a plurality of connecting plates connecting the outer hub and the inner hub. The second motor is installed inside the inner hub, and the rotor is located on the front side of the inner hub and is connected to the second motor.

[0013] Further, a protective cover extending forward is provided at the front edge of the outer hub. The protective cover is a hollow structure, and the rotor is located inside the protective cover.

[0014] Further, the rotor includes two spiral blades and a blade bracket. One ends of the two spiral blades coincide and are fixed to the blade bracket, and the blade bracket is connected to the second motor.

[0015] Further, the first motor is connected to the traveling wheels through a gear set. The gear set includes a driving gear and a driven gear. The driving gear is rotatably mounted on the fixed bracket. The driven gear is sleeved and mounted on the inner ring of the hub. The driving gear and the driven gear are meshed, and the first motor is connected to the driving gear.

[0016] Further, a radar bracket extending upward is provided at the top of the frame, and the lidar is mounted on the radar bracket.

[0017] Further, the frame is rectangular, and the number of the wall climbing mechanisms is four. The four wall climbing mechanisms are respectively arranged at the four corners of the frame.

[0018] In addition, an embodiment of the present invention further provides a motion control method for a flight-wall climbing dual-mode conversion unmanned aerial vehicle, which is applied to the above-mentioned flight-wall climbing dual-mode conversion unmanned aerial vehicle and includes the following steps:

[0019] S1. Obtain the target wall surface features and the current state information of the unmanned aerial vehicle through the lidar;

[0020] S2. Establish a modal conversion dynamics model by combining the target wall surface features and the current state information of the unmanned aerial vehicle;

[0021] S3. Taking the modal conversion dynamics model as a constraint and minimizing the state tracking error and the control cost as the goal, construct a cost function, and use the gradient method to solve the cost function online to obtain the optimal adsorption force adjustment curve and the optimal trajectory control command;

[0022] S4. According to the optimal trajectory control command, control the input of the second motor of each wall climbing mechanism to drive the rotor to rotate, so that the unmanned aerial vehicle approaches the target wall surface, and control the vacuum pump to adjust the adsorption force according to the adsorption force adjustment curve, so that the adsorption mechanism adsorbs on the target wall surface, and control the first servo and the second servo of each modal conversion mechanism to rotate, so that each traveling wheel contacts the target wall surface, so that the unmanned aerial vehicle is converted from the flight mode to the wall climbing mode;

[0023] S5. In the wall climbing mode, control the first motor to drive the traveling wheels to rotate and control the vacuum pump to adjust the adsorption force, and coordinately control the propulsion force and the adsorption force to make the traveling wheels move on the wall surface.

[0024] Further, the modal conversion dynamics model in step S2 includes the dynamics equation in the flight mode and the dynamics equation in the wall climbing mode;

[0025] The dynamics equation in the flight mode is:

[0026]

[0027] Among them, M(q) is the mass matrix, is the Coriolis force matrix, G(q) is the gravity term, τ is the external disturbance torque, and u is the control input;

[0028] The dynamic equation in the wall - climbing mode is:

[0029]

[0030] Among them, F adhesion is the adsorption force, and the expression of the adsorption force is:

[0031] F adhesion = k adhesion ·p

[0032] Among them, k adhesion is the adsorption force coefficient, and p is the air pressure in the adsorption cavity;

[0033] The cost function in step S3 is:

[0034]

[0035] Among them, α and β are weighting coefficients, q state (t) represents the state variable of the UAV,

[0036] q ref (t) represents the desired state, and u(t) represents the control input;

[0037] The control input of the optimal trajectory control command is determined according to the following method:

[0038] Design the mode - conversion function λ(t), whose value smoothly transitions between the flight mode and the wall - climbing mode:

[0039]

[0040] Among them, T transition is the duration of the mode conversion;

[0041] The control input is:

[0042] u(t)=λ(t)·u flight (t)+(1 - λ(t))·u adhesion (t)

[0043] Among them, U flight (t) is the control input in the flight mode, and U adhesion (t) is the adsorption - force control input.

[0044] The beneficial effects brought by the technical solutions provided by the embodiments of the present invention are:

[0045] 1. A flight-wall climbing dual-mode conversion unmanned aerial vehicle of the present invention has a flight mode and a wall climbing mode. In the flight mode, each wall climbing mechanism generally maintains a horizontal state, and the second motor drives the rotor to rotate, enabling the unmanned aerial vehicle to fly stably to the target wall surface. When it is necessary to switch to the wall climbing mode, the adsorption mechanism extracts negative pressure inside the sealing cover through a vacuum pump, prompting the soft skirt to closely fit the target wall surface. The mode conversion mechanism drives each wall climbing mechanism to tilt, and the walking wheels of the wall climbing mechanism come into contact with the target wall surface, achieving a stable and reliable adsorption effect on complex curved surfaces. In the wall climbing mode, when the adsorption mechanism successfully contacts the target wall surface, each wall climbing mechanism can also drive the walking wheels through the first motor to make it walk flexibly on the target wall surface, thereby realizing the attitude adjustment of the unmanned aerial vehicle and achieving a smooth and efficient switch between the flight mode and the wall climbing mode of the unmanned aerial vehicle.

[0046] 2. A motion control method for a flight-wall climbing dual-mode conversion unmanned aerial vehicle of the present invention. During the process of converting from the flight mode to the wall climbing mode, a lidar is used to obtain the target wall surface features and the relative attitude information of the unmanned aerial vehicle. Combining the dynamic model and adsorption characteristics of the unmanned aerial vehicle, a mode conversion dynamic model is constructed. The model predictive control method is used to calculate the optimal adsorption force adjustment curve and the optimal trajectory control command in real time. During the contact process between the unmanned aerial vehicle and the target wall surface, according to the optimal trajectory control command, the rotor of the wall climbing mechanism is controlled to make the unmanned aerial vehicle approach the target wall surface, and at the same time, the adsorption force size is accurately regulated according to the optimal adsorption force adjustment curve. According to the relative position and speed between the unmanned aerial vehicle and the wall surface, the target value of the adsorption force is calculated in real time to ensure that the unmanned aerial vehicle can smoothly transition to the wall surface and maintain stable attachment. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 is a schematic diagram of a flight-wall climbing dual-mode conversion unmanned aerial vehicle of the present invention;

[0048] Figure 2 is a schematic diagram of the flight mode of a flight-wall climbing dual-mode conversion unmanned aerial vehicle of the present invention;

[0049] Figure 3 is a schematic diagram of the adsorption mechanism;

[0050] Figure 4 is the first schematic diagram of the wall climbing mechanism;

[0051] Figure 5 is the second schematic diagram of the wall climbing mechanism;

[0052] Figure 6 is a schematic diagram of the mode conversion mechanism;

[0053] Figure 7 is a schematic diagram of the process of converting a flight-wall climbing dual-mode conversion unmanned aerial vehicle of the present invention from the flight mode to the wall climbing mode;

[0054] Figure 8 This is a schematic diagram of the wall - climbing mode of a flight - wall - climbing dual - mode conversion unmanned aerial vehicle according to the present invention.

[0055] In the figure: 1, frame; 101, radar support; 102, lidar; 2, adsorption mechanism; 201, vacuum pump; 202, fixed plate; 203, sealing cover; 204, movable plate; 205, soft skirt; 206, support column; 3, wall - climbing mechanism; 301, outer ring of the hub; 302, inner ring of the hub; 303, connecting plate; 304, spiral blade; 305, blade support; 306, support plate; 307, first motor; 308, second motor; 309, protective cover; 310, hollow hole; 311, driving gear; 312, driven gear; 4, mode - conversion mechanism; 401, first servo; 402, second servo; 403, servo support. Detailed implementation manners

[0056] To make the objectives, technical solutions and advantages of the present invention clearer, the embodiments of the present invention will be further described below with reference to the accompanying drawings. The following describes a relatively superior one among multiple possible embodiments of the present invention, aiming to provide a basic understanding of the present invention, but not aiming to identify the key or decisive elements of the present invention or limit the scope to be protected.

[0057] In all the examples shown and discussed here, any specific value should be interpreted as merely exemplary, rather than as a limitation. Therefore, other examples of the exemplary embodiments may have different values.

[0058] For technologies, methods and devices known to those of ordinary skill in the relevant art, they may not be discussed in detail, but where appropriate, the said technologies, methods and devices should be regarded as part of the description.

[0059] It should be noted that: Similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings. At the same time, it should be understood that, for the sake of description, the dimensions of the various parts shown in the drawings are not drawn in actual proportional relationships.

[0060] It should be noted that, unless otherwise clearly specified and limited, the terms "installation" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0061] Please refer to Figure 1 and Figure 2 , an embodiment of the present invention provides a flight-wall climbing dual-mode conversion unmanned aerial vehicle, including a frame 1, an adsorption mechanism 2, a plurality of wall climbing mechanisms 3, a mode conversion mechanism 4, and a controller.

[0062] Wherein the frame 1 is a carrying platform, and a lidar 102 is provided on the top thereof. The lidar 102 is used for target wall features and the current state information of the unmanned aerial vehicle. The wall features include the position and angle of the wall and the relative position between the unmanned aerial vehicle and the wall.

[0063] The shape of the frame 1 can be flexibly selected according to the actual application scenario. For example, in this embodiment, the frame 1 is rectangular, specifically a rectangular frame structure. An upward-extending radar bracket 101 is provided on the top of the frame 1, and the lidar 102 is installed on the radar bracket.

[0064] Please refer to Figure 3 , the adsorption mechanism 2 is arranged at the bottom of the frame 1. The adsorption mechanism 2 mainly includes an adsorption cavity, a vacuum pump 201, and a pressure sensor. The vacuum pump 201 is connected to the adsorption cavity. A soft skirt 205 is provided at the lower end of the adsorption cavity, and the pressure sensor is arranged in the adsorption cavity to detect the air pressure in the adsorption cavity.

[0065] The adsorption cavity includes a fixing plate 202, a sealing cover 203, and a movable plate 204. The fixing plate 202 is fixed to the bottom surface of the frame 1. A plurality of support columns 206 are provided on the fixing plate 202, and the upper ends of the support columns 206 are fixedly connected to the bottom surface of the frame 1. The vacuum pump 201 is installed on the fixing plate 202 and communicates with the inside of the sealing cover 203. The upper end of the sealing cover 203 is connected to the fixing plate 202, and the lower end is connected to the movable plate 204. The upper end of the soft skirt 205 is connected to the movable plate 204 and is arranged around the movable plate 204 for one week.

[0066] The soft skirt 205 is generally a rubber skirt. The vacuum pump 201 can pump negative pressure into the sealing cover 203 to make the soft skirt 205 contact and adsorb on the surface of the measured object. When the surface of the measured object is a curved surface or other undulating surfaces, the soft skirt 205 can adaptively deform according to the surface shape of the measured object, so as to stably contact and adsorb on the surface of the measured object.

[0067] In some embodiments, the sealing cover 203 is a multi-layer folded cavity structure. Thus, when the vacuum pump 201 pumps negative pressure into the sealing cover 203, the sealing cover 203 can be folded, reducing the length of the sealing cover 203, so as to more stably contact and adsorb on the surface of the measured object.

[0068] Please refer to Figure 4 and Figure 5 The wall-climbing mechanism 3 is generally provided in multiple numbers, and each of the mode conversion mechanisms 4 is arranged at intervals around the frame 1, and each mode conversion mechanism 4 is connected to one wall-climbing mechanism 3.

[0069] Each of the wall-climbing mechanisms 3 includes a fixed bracket, a traveling wheel, a rotor, a first motor 307 and a second motor 308. The traveling wheel is rotatably installed on the fixed bracket. The first motor 307 is connected to the traveling wheel to drive the traveling wheel to rotate. The rotor is installed in the traveling wheel, and the second motor 308 is connected to the rotor to drive the rotor to rotate.

[0070] Specifically, the traveling wheel includes a hub. The hub includes an outer hub 301, an inner hub 302, and a plurality of connecting plates 303 connected between the outer hub 301 and the inner hub 302. The outer hub 301 and the inner hub 302 are coaxially arranged. The number of the connecting plates 303 is generally set to three or more. In this embodiment, the number of the connecting plates 303 is set to three. Each of the connecting plates 303 is generally arranged at uniform intervals around the inner hub 302. The second motor 308 is installed in the inner hub 302. The rotor is located on the front side of the inner hub 302 and is connected to the second motor 308. The first motor 307 and the second motor 308 can both be selected as motors, and the rotation of the motors is controlled to control the rotation of the hub and the rotor.

[0071] In some embodiments, the first motor 307 is connected to the traveling wheel through a gear set. The gear set includes a driving gear 311 and a driven gear 312. The driving gear 311 is rotatably installed on the fixed bracket. The driven gear 312 is sleeved on the inner hub 302. The driving gear 311 and the driven gear 312 are meshed. The first motor 307 is connected to the driving gear 311.

[0072] The rotor can flexibly select various UAV rotors according to actual applications. In some embodiments, the rotor includes two spiral blades 304 and a blade bracket 305. One ends of the two spiral blades 304 coincide and are fixed to the blade bracket 305. The blade bracket 305 is connected to the second motor 308.

[0073] In some embodiments, a protective cover 309 extending forward is further provided at the front side edge of the outer ring 301 of the hub, and the rotor is located within the protective cover 309. The protective cover 309 is arranged circumferentially around the outer ring 301 of the hub, and the rotation diameter of the rotor is smaller than the inner diameter of the protective cover 309. To enable the air flow to be discharged more smoothly when the rotor rotates, the protective cover 309 is a hollow structure. For example, a circle of hollow holes 310 is provided on the side wall of the protective cover 309 to accelerate the air flow.

[0074] Please refer to Figure 6 and Figure 8 , each of the mode conversion mechanisms 4 is arranged at intervals around the frame 1. Each mode conversion mechanism 4 is connected to one of the wall climbing mechanisms 3. Each mode conversion mechanism 4 includes a first servo 401 and a second servo 402. The first servo 401 is fixedly installed on the frame 1 and its output end is connected to the second servo 402. The output end of the second servo 402 is connected to a fixed bracket. The first servo 401 and the second servo 402 are used to drive the wall climbing mechanism 3 to rotate around two mutually perpendicular rotation axes, so that the walking wheels can walk on a curved surface.

[0075] Specifically, the first servo 401 is a single-axis servo, and the second servo 402 is a double-axis servo. The single-axis servo is fixedly installed on the servo bracket 403. The output shaft of the single-axis servo is arranged along the front-rear direction, extends out of the servo bracket 403 and is connected to the double-axis servo. The fixed bracket includes two relatively arranged support plates 306. The two output shafts of the double-axis servo extend left and right respectively, and are respectively connected to one end of the two support plates 306. The two output shafts of the double-axis servo synchronously drive the two support plates 306 to rotate. The other ends of the two support plates 306 are connected to the rear end of the inner ring 302 of the hub, thereby connecting the walking wheels.

[0076] It should be noted that the number of the wall climbing mechanisms 3 can be flexibly set according to the walking needs of the frame 1. In this embodiment, for example, the number of the wall climbing mechanisms 3 is four, and the four wall climbing mechanisms 3 are respectively arranged at the four corners of the frame 1.

[0077] Please refer to Figure 7, the controller is installed inside the frame 1, and the controller is respectively connected to the lidar 102, the vacuum pump 201, the pressure sensor, the first motor 307, the second motor 308, the first servo 401 and the second servo 402. The controller is used to obtain the target wall surface features by the lidar 102, control the second motor 308 to drive the rotor to rotate to make the drone approach the target wall surface, control the first servo 401 and the second servo 402 to rotate to adjust the attitude of the drone, the vacuum pump 201 adjusts the air pressure in the adsorption cavity to make the adsorption cavity adsorb to the target wall surface, and control the first motor 307 to drive the walking wheels to move on the target wall surface.

[0078] A flight-wall-climbing dual-mode conversion drone of the present invention has a flight mode and a wall-climbing mode. In the flight mode, each wall-climbing mechanism 3 generally maintains a horizontal state, and the second motor 308 drives the rotor to rotate, enabling the drone to stably fly to the target wall surface; when it is necessary to switch to the wall-climbing mode, the adsorption mechanism 2 extracts negative pressure inside the sealing cover through the vacuum pump 201, prompting the soft skirt to closely fit the target wall surface. The mode conversion mechanism drives the walking wheels of each wall-climbing mechanism 3 to incline and contact the target wall surface, achieving a stable and reliable adsorption effect on complex curved surfaces; in the wall-climbing mode, while the adsorption mechanism 2 successfully contacts the target wall surface, each wall-climbing mechanism 3 can also drive the walking wheels through the first motor 307 to flexibly walk on the target wall surface, thereby realizing the attitude adjustment of the drone and realizing the smooth and efficient switching of the drone between the flight mode and the wall-climbing mode.

[0079] In addition, considering Figure 7 , an embodiment of the present invention further provides a motion control method for a flight-wall-climbing dual-mode conversion drone, which is applied to the above-mentioned flight-wall-climbing dual-mode conversion drone and includes the following steps:

[0080] S1. Obtain the target wall surface features and the current state information of the drone through the lidar 102.

[0081] First, when the drone flies to a range outside the preset range near the target wall surface in the flight mode, the drone adopts the TMINCO (Timing Minimum Control Force Method) to generate the optimal four-rotor flight trajectory in the flight mode. This method utilizes the differential flatness characteristic of the multi-rotor system, and by mapping the translational motion to a single flat output space, the trajectory optimization model is greatly simplified. The specific method is as follows:

[0082] First, define a flat output function y(t), which represents the deviation of the drone trajectory:

[0083] y(t) = q(t) - q 0 (t)

[0084] Among them, q 0 (t) is the target trajectory, and q(t) is the actual trajectory. The relationship between the control input and the trajectory can be expressed as:

[0085]

[0086] This formula derives the required control input through the dynamic equation and constraint conditions. The control input is the magnitude of the lift generated by the rotor, and the adjustment of the input is achieved by controlling the second motor 308.

[0087] By optimizing the objective to minimize the total change in the control input, energy consumption is reduced and the trajectory is smoothed. The objective function is as follows:

[0088]

[0089] The objective function requires minimizing the change in the control input within a given time interval.

[0090] During the actual flight of the UAV, a set of time intervals and intermediate waypoints are first selected, and the entire trajectory is discretized into multiple segments. Within each segment, the flat output function of the UAV is expressed as a high-order polynomial according to the above method, and the analytical relationship between the polynomial coefficients and the control input is solved based on the dynamic model. Then, by minimizing the change rate of the control input over the entire trajectory, a convex quadratic programming problem is constructed to solve for the optimal polynomial coefficients.

[0091] After obtaining the flat output polynomial, the state variables and control variables of the UAV, such as position, velocity, acceleration, and angular velocity, can be easily solved inversely. Compared with traditional trajectory optimization methods, TMINCO avoids a large number of numerical integrations and iterative operations, generates a smooth trajectory with continuous acceleration, and can fully consider the dynamic constraints of the UAV, making it very suitable for real-time applications.

[0092] In this way, on the one hand, this UAV can quickly generate the optimal trajectory of the UAV from the starting point to the ending point according to the waypoint sequence of the global trajectory planning; on the other hand, it can adjust the local trajectory in real time to cope with environmental disturbances, such as obstacle avoidance and wind disturbances.

[0093] During the flight of the UAV, the lidar 102 continuously scans the front. When it reaches the preset range near the target wall surface, it obtains the target wall surface characteristics and the current state information of the UAV, and sends the target wall surface characteristics and the current state information of the UAV to the controller. The wall surface characteristics include the position, angle of the wall surface, and the relative position between the UAV and the wall surface. The current state information of the UAV includes position, velocity, attitude, etc.

[0094] S2. Establish a modal conversion dynamic model by combining the target wall surface characteristics and the current state information of the UAV.

[0095] In the step S2, the modal conversion dynamic model includes the dynamic equations in the flight mode and the dynamic equations in the wall - climbing mode;

[0096] The dynamic equation in the flight mode is:

[0097]

[0098] where, M(q) is the mass matrix, representing the inertial characteristics of the UAV;

[0099] is the Coriolis force matrix, which includes the moment of inertia of the UAV and the action of external forces;

[0100] G(q) is the gravity term, representing the influence of gravity on the UAV;

[0101] τ is the external disturbance torque, representing wind force or other external disturbances;

[0102] u is the control input, representing the thrust generated by the rotation of the rotor driven by the second motor 308;

[0103] In the wall - climbing mode, in addition to the flight control input, the action of the adsorption force needs to be considered. Therefore, the dynamic equation in the wall - climbing mode is:

[0104]

[0105] where F adhesion the adsorption force, is expressed as:

[0106] F adhesion = k adhesion ·p

[0107] where:

[0108] k adhesion : the adsorption force coefficient, representing the adhesion characteristics of the material.

[0109] p: the air pressure in the adsorption cavity, representing the driving source of the adsorption force.

[0110] S3. Taking the modal conversion dynamic model as a constraint, with the goal of minimizing the state tracking error and the control cost, construct a cost function, and use the gradient method to solve the cost function online to obtain the optimal adsorption force adjustment curve and the optimal trajectory control command.

[0111] Here, first, optimize the timing of the UAV's transition from the flight mode to the wall - climbing mode. Define a cost function to minimize the changes in the control input and the adsorption force during the switching process. The cost function is used to evaluate the deviation of the control input and the state variables.

[0112] The cost function is as follows:

[0113] J = ∫ 0 T (α·||q state (t) - q ref (t)|| 2 + β·||u(t)|| 2 )dt

[0114] Where α and β are weighting coefficients used to balance the weights of the state error and the control input;

[0115] q state (t) represents the state variable of the UAV;

[0116] q ref (t) represents the desired state;

[0117] u(t) represents the control input.

[0118] When switching between the flight mode and the wall - climbing mode, the control input needs to have a smooth transition to avoid instability.

[0119] When the UAV switches from the flight mode to the wall - climbing mode, the control input of the optimal trajectory control command is determined as follows:

[0120] Design a modal transition function λ(t) whose value transitions smoothly between the flight mode and the wall - climbing mode:

[0121]

[0122] Where T transition is the duration of the mode transition.

[0123] The control input is:

[0124] u(t) = λ(t)·u fight (t)+(1 - λ(t))·u adhesion (t)

[0125] Where U flight (t) is the control input in the flight mode, and U adhesion (t) is the adsorption force control input.

[0126] During the process of the UAV switching from the flight mode to the wall - climbing mode, through this control input, the UAV will gradually reduce its speed in the flight mode and increase the adsorption force, and finally complete the wall - climbing - type switch. This ensures a smooth transition of the control input during the mode transition and avoids instability caused by sudden changes.

[0127] To achieve a smooth transition to the wall - climbing mode, kinematic and dynamic constraints are utilized to limit the sudden change of control inputs during the conversion process, and a linear interpolation method is adopted to smoothly transition the speed and adsorption force.

[0128] Moreover, a gradient optimization algorithm is employed to adjust the control inputs in real - time to ensure the optimality of the trajectory in a dynamic environment. The gradient descent method is used to update the control inputs, thereby approaching the optimal trajectory, and thus obtaining the optimal adsorption force adjustment curve and the optimal trajectory control command.

[0129] S4. Control the input of the second motor 308 of each of the wall - climbing mechanisms 3 according to the optimal trajectory control command, drive the rotor to rotate, make the UAV approach the target wall surface, and control the vacuum pump 201 to adjust the magnitude of the adsorption force according to the adsorption force adjustment curve, so that the adsorption mechanism 2 adsorbs to the target wall surface, and control the first servo 401 and the second servo 402 of each of the mode conversion mechanisms to rotate, so that each of the walking wheels contacts the target wall surface, thereby converting the UAV from the flight mode to the wall - climbing mode.

[0130] S5. In the wall - climbing mode, control the first motor 307 to drive the walking wheels to rotate and the vacuum pump 201 to adjust the magnitude of the adsorption force, coordinately control the propulsion force and the adsorption force, so that the walking wheels move on the wall surface.

[0131] In steps S4 and S5, the adjustment of the adsorption force of the adsorption mechanism 2 adopts a closed - loop control scheme based on pressure feedback, and precisely controls the change of the adsorption force by adjusting the negative pressure in the adsorption cavity in real - time.

[0132] Specifically, the controller collects the air pressure information in the adsorption cavity in real - time through a pressure sensor, compares it with the target pressure value determined by the optimal adsorption force adjustment curve, calculates the control error, and then obtains the output through a PID controller to drive the opening of the electro - control proportional valve of the vacuum pump 201. The proportional valve adjusts the pumping rate of the vacuum pump 201, and the negative pressure change is further transmitted to the adsorption cavity, forming a force - control closed - loop.

[0133] The parameters of the PID controller can be calibrated on the ground to enable the closed - loop system to achieve fast, accurate, and stable pressure tracking. To further improve the control performance, a feed - forward compensation and an adaptive correction mechanism are also introduced. The former compensates the proportional valve in advance according to the expected change rate of the adsorption force to reduce the lag error; the latter identifies the adsorption force model parameters in real - time during flight and automatically corrects the control gain.

[0134] The closed - loop control of the adsorption force can adopt the classic PID control algorithm to ensure the smooth adjustment of the adsorption force:

[0135]

[0136] Among them, e is the adsorption force error (the difference between the target adsorption force and the actual adsorption force), K p , K d , K i are the gains of the PID controller, is the change rate of the adsorption force error.

[0137] The adsorption force closed-loop control system of the adsorption mechanism 2 improves the force tracking accuracy through robust control, effectively ensuring the high quality and repeatability of the attachment process.

[0138] In this article, the front, back, up, down and other orientation words are defined based on the positions of the components in the drawings and the positions of the components relative to each other, just for the sake of clarity and convenience in expressing the technical solution. It should be understood that they are relative concepts and can change accordingly according to different usage and placement methods. The use of the orientation words should not limit the scope of protection claimed in this application.

[0139] Without conflict, the above embodiments and the features in the embodiments in this article can be combined with each other. The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A flying-wall climbing dual-mode conversion UAV, characterized in that: include: a rack with a lidar on top; An adsorption mechanism is arranged at the bottom of the frame, and comprises an adsorption chamber, a vacuum pump and a pressure sensor. The vacuum pump is connected to the adsorption chamber, a soft skirt is arranged at the lower end of the adsorption chamber, and the pressure sensor is arranged in the adsorption chamber to detect the air pressure in the adsorption chamber; A plurality of wall crawling mechanisms, comprising a fixed bracket, a walking wheel, a rotor, a first motor and a second motor, wherein the walking wheel is rotatably mounted on the fixed bracket, the first motor is connected to the walking wheel to drive the walking wheel to rotate, the rotor is mounted in the walking wheel, and the second motor is connected to the rotor to drive the rotor to rotate; A plurality of mode conversion mechanisms, each of which is arranged at intervals around the frame, each of which is connected to one of the wall crawling mechanisms, each of which comprises a first steering gear and a second steering gear, the first steering gear is fixedly mounted on the frame and an output end of which is connected to the second steering gear, an output end of the second steering gear is connected to one of the fixed brackets, and the first steering gear and the second steering gear are used to drive the wall crawling mechanism to rotate around two rotation axes perpendicular to each other; and a controller, which is respectively connected to the laser radar, the vacuum pump, the pressure sensor, the first motor, the second motor, the first steering gear and the second steering gear, wherein the controller is used to obtain target wall features from the laser radar, control the second motor to drive the rotor to rotate so that the UAV approaches the target wall, control the first steering gear and the second steering gear to rotate to adjust the posture of the UAV, the vacuum pump to adjust the air pressure in the adsorption chamber so that the adsorption chamber is adsorbed to the target wall, and control the first motor to drive the walking wheel to move on the target wall.

2. The flying-wall climbing dual-mode conversion UAV according to claim 1, characterized in that: The adsorption chamber includes a fixed plate, a sealing cover and a movable plate, wherein the fixed plate is fixed to the bottom of the frame, the sealing cover is a multi-layer folded cavity structure, the upper end of the sealing cover is connected to the fixed plate, and the lower end is connected to the movable plate, and the upper end of the soft skirt is connected to the movable plate and is arranged around the movable plate.

3. The flying-wall climbing dual-mode conversion UAV according to claim 1, characterized in that: The walking wheel includes a hub, and the hub includes a hub outer ring, a hub inner ring, and a plurality of connecting plates connected between the hub outer ring and the hub inner ring. The second motor is installed in the hub inner ring, and the rotor is located on the front side of the hub inner ring and is connected to the second motor.

4. The flying-wall climbing dual-mode conversion UAV according to claim 3, characterized in that: The front edge of the hub outer ring is also provided with a protective cover extending forward, the protective cover is a hollow structure, and the rotor is located inside the protective cover.

5. The flying-wall climbing dual-mode conversion UAV according to claim 3, characterized in that: The rotor includes two spiral blades and a blade bracket. One ends of the two spiral blades overlap and are fixed on the blade bracket. The blade bracket is connected to the second motor.

6. The flying-wall climbing dual-mode conversion UAV according to claim 3, characterized in that: The first motor is connected to the travel wheel through a gear set, the gear set includes a driving gear and a driven gear, the driving gear is rotatably mounted on the fixed bracket, the driven gear is sleeved and mounted on the inner ring of the wheel hub, the driving gear and the driven gear are meshed, and the first motor is connected to the driving gear.

7. The flying-wall climbing dual-mode conversion UAV according to claim 1, characterized in that: A radar bracket extending upward is provided on the top of the frame, and the laser radar is installed on the radar bracket.

8. The flying-wall climbing dual-mode conversion UAV according to claim 1, characterized in that: The frame is rectangular, and the number of the wall crawling mechanisms is four, and the four wall crawling mechanisms are respectively arranged at the four corners of the frame.

9. A motion control method for a flying-wall climbing dual-mode conversion UAV, characterized in that: The invention is applied to a flying-wall climbing dual-mode conversion UAV as claimed in any one of claims 1 to 8, and comprises the following steps: S1, obtaining target wall features and current status information of the UAV through laser radar; S2, establishing a mode conversion dynamics model based on the target wall characteristics and the current state information of the UAV; S3, taking the mode conversion dynamics model as the constraint and minimizing the state tracking error and control cost as the goal, construct a cost function, and use the gradient method to solve the cost function online to obtain the optimal adsorption force adjustment curve and the optimal trajectory control command; S4, controlling the input of the second motor of each of the wall crawling mechanisms according to the optimal trajectory control command, driving the rotor to rotate, so that the UAV approaches the target wall, and controlling the vacuum pump to adjust the magnitude of the adsorption force according to the optimal adsorption force adjustment curve, so that the adsorption mechanism is adsorbed on the target wall, and controlling the first steering gear and the second steering gear of each of the mode conversion mechanisms to rotate, so that each of the walking wheels contacts the target wall, so that the UAV is converted from the flight mode to the wall climbing mode; S5. In the wall climbing mode, the first motor is controlled to drive the running wheel to rotate and the vacuum pump to adjust the size of the adsorption force, and the propulsion force and the adsorption force are coordinated and controlled to make the running wheel move on the wall.

10. The motion control method of a flying-wall climbing dual-mode conversion UAV as claimed in claim 9, characterized in that: The mode conversion dynamics model in step S2 includes a dynamics equation in a flight mode and a dynamics equation in a wall climbing mode; The dynamic equation in flight mode is: Where M(q) is the mass matrix, is the Coriolis force matrix, G(q) is the gravity term, τ is the external disturbance torque, and u is the control input; The dynamic equation in the wall climbing mode is: Among them, F adhesion is the adsorption force, and the expression of the adsorption force is: F adhesion =k adhesion ·p Among them, k adhesion is the adsorption force coefficient, p is the gas pressure in the adsorption chamber; The cost function in step S3 is: Among them, α and β are weighting coefficients, q state (t) represents the state variable of the UAV, q ref (t) represents the desired state, u(t) represents the control input; The control input of the optimal trajectory control command is determined as follows: Design the mode transfer function λ(t) so that its value smoothly transitions between the flight mode and the wall climbing mode: Among them, T transition is the duration of the mode shift; The control input is: u(t)=λ(t)·u flight (t)+(1-λ(t))·u adhesion (t) Among them, U flight (t) is the control input in flight mode, U adhesion (t) is the adsorption force control input.

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