A variable stiffness folding structure for complex pipeline parking and obstacle avoidance of unmanned aerial vehicles

Abstract

The application relates to a variable stiffness folding structure for complex pipeline parking and obstacle avoidance of a UAV, which comprises a UAV body, a driving control system, a variable stiffness wing joint and a clamping mechanism. The UAV body comprises a driving part and a folding part, the driving part is located on both sides of the folding part, and the folding part is a U-shaped plate. The variable stiffness wing joint is located at the connection between the driving part and the folding part, the driving control system is located on the driving part, and the clamping mechanism is located on the inner edge of the U-shaped plate. The variable stiffness wing joint comprises a variable stiffness element, a hinge assembly and a heating resistance wire. The hinge assembly is rotationally connected with the driving part and the folding part. The variable stiffness element covers the hinge assembly and the joint of the driving part and the folding part. The heating resistance wire is embedded in the variable stiffness element in a curve shape. The material of the variable stiffness element is a shape memory polymer. Compared with the prior art, the application has the advantages of simple overall structure, easy installation, modification and maintenance, improved flexibility and multifunctionality of the UAV and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of variable structure robots, in particular to a variable stiffness folding and unfolding structure for complex pipeline parking and obstacle avoidance of unmanned aerial vehicles. BACKGROUND

[0002] With the progress of material science and precision manufacturing technology, the field of variable structure unmanned aerial vehicles has been widely researched and developed. The advantages of variable structure unmanned aerial vehicles mainly lie in realizing special functions, space optimization, convenient carrying and deployment, etc.

[0003] The current variable structure unmanned aerial vehicles generally use motor-driven folding and unfolding mechanisms. The relatively high weight and volume of the motor restrict the load capacity and maneuverability of the unmanned aerial vehicle, and its relatively slow folding and unfolding deformation and response speed also limit the performance of the folding and unfolding mechanism itself. Therefore, it is crucial to achieve fast response and deformation under the restriction of small weight and volume for improving the overall performance of the variable structure unmanned aerial vehicle, which has important research significance and application value.

[0004] The current variable structure unmanned aerial vehicles generally use motor-driven folding and unfolding mechanisms. The relatively high weight and volume of the motor restrict the load capacity and maneuverability of the unmanned aerial vehicle, and its relatively slow folding and unfolding deformation and response speed also limit the performance of the folding and unfolding mechanism itself. Therefore, it is crucial to achieve fast response and deformation under the restriction of small weight and volume for improving the overall performance of the variable structure unmanned aerial vehicle, which has important research significance and application value.

[0005] In current practical applications, the shape and volume of the unmanned aerial vehicle are fixed, and it cannot pass through a hole or channel with a diameter smaller than the fixed body of the unmanned aerial vehicle. The fixed body length and volume shape of the unmanned aerial vehicle limit the flexibility and maneuverability of the unmanned aerial vehicle. In addition, the unmanned aerial vehicle has to control the blade rotation to achieve hovering, which increases the energy consumption and waste. Therefore, it is of great research benefit and economic value to use the deformation ability of the variable structure unmanned aerial vehicle to achieve parking and obstacle avoidance. SUMMARY

[0006] The purpose of the present application is to overcome the defects of the prior art and provide a variable stiffness folding and unfolding structure for complex pipeline parking and obstacle avoidance of unmanned aerial vehicles, which can change its shape to complete the clamping and obstacle avoidance tasks and realize the multifunctionalization of the unmanned aerial vehicle.

[0007] The purpose of the present application can be achieved by the following technical solutions:

[0008] The present invention provides a variable stiffness foldable structure for UAVs to stop and avoid obstacles in complex pipelines. The structure includes a UAV body, a drive control system, a variable stiffness wing joint, and a clamping mechanism. The UAV body includes a drive portion and a folding portion. The drive portion is located on both sides of the folding portion, which is a U-shaped plate. The variable stiffness wing joint is located at the connection between the drive portion and the folding portion. The drive control system is located on the drive portion, and the clamping mechanism is located on the inner edge of the U-shaped plate.

[0009] The variable stiffness wing joint includes a variable stiffness element, a hinge assembly and a heating resistor wire. The hinge assembly rotates to connect the driving part and the folding part. The variable stiffness element covers the hinge assembly and the joint between the driving part and the folding part. The heating resistor wire is embedded in the variable stiffness element in a curved shape. The material of the variable stiffness element is shape memory polymer.

[0010] Furthermore, the drive control system includes a brushless motor, a rotor and a drone control board. There are multiple rotors and they are installed on the surface of the drive unit. The brushless motor is installed at the rotating shaft of the rotor. The drone control board is connected to the brushless motor and the heating resistor wire.

[0011] Furthermore, the drone body is divided into an upper layer and a lower layer. The upper and lower layers share a rotor and a brushless motor and are installed in a coaxial position. The driving parts and folding parts of the upper and lower layers are respectively connected and the connection positions are staggered.

[0012] Furthermore, the variable stiffness element and the folding part, the variable stiffness element and the driving part, the driving part and the rotor, the brushless motor and the rotor, and the upper and lower layers of the drone body are all fixedly connected by bolts and nuts.

[0013] Furthermore, shape memory polymers have a critical temperature Tg. When the temperature is lower than Tg, the material properties of the shape memory polymers are rigid, and when the temperature is higher than Tg, the material properties of the shape memory polymers are flexible.

[0014] Furthermore, the drone control board controls the on and off of the heating resistor wire through a self-heating circuit. When the heating resistor wire is energized, the shape memory polymer is heated, and the temperature of the shape memory polymer rises above Tg; when the heating resistor wire is de-energized, the heating of the shape memory polymer stops, and the temperature of the shape memory polymer drops below Tg.

[0015] Furthermore, the variable stiffness element is in the shape of a long strip.

[0016] Furthermore, the clamping mechanism includes triangular serrations distributed along the inner edge of the U-shaped plate.

[0017] Furthermore, the triangular serrations are distributed parallel to the seam between the driving portion and the folding portion.

[0018] Further, the triangular sawtooth is made of thermoplastic polyurethane.

[0019] Compared with the prior art, the present application has the following advantages:

[0020] 1、The unmanned aerial vehicle body of the present application comprises a driving part and a folding part, and the driving part is located on both sides of the folding part, the folding part is a U-shaped plate, and a variable stiffness wing joint composed of a variable stiffness element, a hinge assembly and a heating resistance wire is arranged at the connection between the driving part and the folding part; a plurality of rotors controlled by brushless motors are arranged on the driving part, and the brushless motors are used to control the different lift forces on both sides of the unmanned aerial vehicle to realize the deformation of the unmanned aerial vehicle structure; the variable stiffness element made of shape memory polymer (SMP) is used as the deformation joint of the unmanned aerial vehicle, when deformation is needed, the heating resistance wire heats the SMP to soften it, which exhibits flexibility, and the joint is unlocked, when deformation is not needed, the heating resistance wire stops working, and the SMP returns to low temperature, which exhibits rigidity, and the joint is locked; the overall structure is simple, easy to install, modify and maintain, and more suitable for the application environment of high flexibility and multifunctionality of the unmanned aerial vehicle.

[0021] 2、The present application uses a triangular sawtooth-shaped high-compatibility clamping mechanism, which changes the spatial transverse distance of the clamping position by deforming the unmanned aerial vehicle, dynamically adapts to the size of the clamped object, and has a wide adaptation range; thermoplastic polyurethane (TPU) with high friction coefficient is used as the clamping device to ensure that it can be firmly locked on the clamped object under the condition that the structure of the unmanned aerial vehicle is locked. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 It is a schematic diagram of the overall structure when the mechanism in the present application is in a parallel flight state;

[0023] Figure 2 It is a schematic diagram of the overall structure when the mechanism in the present application is in a deformed flight state;

[0024] Figure 3 It is a schematic diagram of the overall structure when the mechanism in the present application is in an extreme deformed flight state;

[0025] Figure 4 It is a schematic diagram of the overall structure when the mechanism in the present application is in an extreme deformed flight state;

[0026] In the figure, 1 is a brushless motor, 2 is a variable stiffness element, 3 is a hinge assembly, 4 is a heating resistance wire, and 5 is a triangular sawtooth. DETAILED DESCRIPTION

[0027] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0028] The present invention relates to a variable stiffness foldable structure for drones to stop and avoid obstacles in complex pipelines. It can be used as a joint variable stiffness foldable drone body applied to variable structure drones, and can also be used in other variable structure robot fields, such as articulated robots. Figure 1 As shown, the structure mainly includes a drive control system for realizing passive folding and unfolding of the UAV, four variable stiffness wing joints, four sets of highly compatible clamping mechanisms, and a UAV body consisting of a drive part and a folding part and divided into two layers, upper and lower.

[0029] Among them, the driving part of the drone body is located on both sides of the folding part, the folding part is a U-shaped plate structure, the variable stiffness wing joint is located at the connection between the driving part and the folding part, and the upper and lower driving parts are respectively connected to the folding part and the connection positions are staggered. The driving control system mainly includes a brushless motor 1, a rotor and a drone control board. There are four brushless motors 1 and four rotors, which are distributed on the driving part in pairs. The brushless motor 1 is installed at the rotating shaft of the rotor. During operation, the brushless motor 1 is controlled by the drone control board to adjust the lift of the four rotors. When the lift of the rotors on the two driving parts is different, the driving part and the folding part can bend along the variable stiffness wing joint to realize the folding action of the drone body, thereby changing the width and geometric shape of the drone body, such as Figure 2 and Figure 3 shown.

[0030] Particularly, the variable stiffness wing joint is composed of a variable stiffness element 2, a hinge assembly 3 and a heating resistance wire 4. Among them, the hinge assembly 3 realizes the rotary pair connection between the driving part and the folding part, the variable stiffness element 2 is a long strip-shaped part covering the long strip-shaped part between the driving part and the folding part, and the material is a shape memory polymer (SMP). For SMP, there is a critical temperature Tg, when the temperature is lower than Tg, the material properties of the shape memory polymer are rigid, and when the temperature is higher than Tg, the material properties of the shape memory polymer are flexible. The heating resistance wire 4 is embedded in the shape memory polymer in a curved shape, and when the heating resistance wire 4 is powered on, the heating resistance wire 4 generates heat, the temperature of the shape memory polymer rises, and when the heating resistance wire 4 is powered off, the heating resistance wire 4 stops generating heat, and the temperature of the shape memory polymer decreases. Therefore, when the heating resistance wire 4 is powered on, the variable stiffness element 2 behaves as a flexible material, and the driving part and the folding part are foldable and movable, at this time the unmanned aerial vehicle body can be folded; when the heating resistance wire 4 is powered off, the variable stiffness element 2 behaves as a rigid material, and the driving part and the folding part are not foldable and fixed, at this time the unmanned aerial vehicle body structure is locked. As a preferred embodiment, the heating resistance wire 4 is embedded in the shape memory polymer in a curved shape, in order to ensure that the whole piece of shape memory polymer can be uniformly heated.

[0031] Particularly, the clamping mechanism is composed of triangular sawtooth 5, and a plurality of triangular sawtooth 5 are distributed on the inner side edge of the folding part of the U-shaped plate structure, and as a preferred embodiment, the triangular sawtooth 5 is distributed at the inner side edge of the folding part parallel to the driving part and the folding part. The material of the triangular sawtooth 5 is selected from thermoplastic polyurethane (TPU), and the TPU material has a high friction coefficient, high elasticity and high adhesion, which improves the adhesion performance of the clamping mechanism to the fixed object such as the pipeline wall.

[0032] In this embodiment, in addition to controlling the brushless motor 1, the unmanned aerial vehicle control panel also controls the on-off of the heating resistance wire 4 through a self-heating circuit as shown in Figure 4 , so as to control the lift of the rotor and the switching of the variable stiffness element 2 between rigid and flexible material properties. When the heating resistance wire 4 is powered on, the variable stiffness element 2 behaves as flexible, at this time the unmanned aerial vehicle control panel controls the brushless motor 1 to control the four rotors to realize the change of the lift, so as to change the shape of the unmanned aerial vehicle in the flexible state of the joint, realize the high flexibility of the shape of the foldable unmanned aerial vehicle; when the unmanned aerial vehicle is adjusted to the appropriate shape, the heating resistance wire 4 is powered off under the control of the unmanned aerial vehicle control panel, the variable stiffness element 2 gradually behaves as rigid, and the triangular sawtooth 5 made of thermoplastic polyurethane in the structure is fixed on the complex pipeline, after the clamping and fixing are completed, the unmanned aerial vehicle realizes the stop in the pipeline, at this time the brushless motor 1 can stop running, reducing the waste of energy.

[0033] In summary, this embodiment uses a brushless motor 1 to control the different lift forces on both sides of the drone to achieve deformation of the drone structure. The deformation does not require an additional power source, avoiding the redundant volume and weight problems caused by the additional motor. Secondly, a shape memory polymer (SMP) is used as the deformation joint of the drone. When deformation is required, the circuit board heats the SMP to soften it, showing flexibility, and the joint is unlocked. When deformation is not required, the circuit board stops working, the SMP returns to a low temperature, showing rigidity, and the joint is locked. Thirdly, the highly compatible clamping mechanism changes the spatial lateral distance of the clamping position by deforming the drone, dynamically adapting to the size of the required clamped object, and having a wide range of adaptability. At the same time, thermoplastic polyurethane (TPU) with a high friction coefficient is used as a clamping device to ensure that it can be firmly locked on the clamped object when the drone structure is locked. Finally, the joint variable stiffness foldable drone proposed in this embodiment has multiple advantages. Its overall structural design is relatively simple, easy to install, modify and maintain, and is more suitable for the application environment of drones with high flexibility and versatility.

[0034] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and such modifications or substitutions are intended to be within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the claims.

Claims

1. A variable stiffness foldable structure for UAVs to stop and avoid obstacles in complex pipelines, characterized by: The drone comprises a main body, a drive control system, a variable stiffness wing joint, and a clamping mechanism. The main body comprises a drive portion and a folding portion, wherein the drive portion is located on both sides of the folding portion, and the folding portion is a U-shaped plate. The variable stiffness wing joint is located at the connection between the drive portion and the folding portion. The drive control system is located on the drive portion, and the clamping mechanism is located at the inner edge of the U-shaped plate. The variable stiffness wing joint comprises a variable stiffness element (2), a hinge assembly (3) and a heating resistance wire (4); the hinge assembly (3) rotatably connects the driving portion and the folding portion; the variable stiffness element (2) covers the hinge assembly (3) and the joint between the driving portion and the folding portion; the heating resistance wire (4) is embedded in the variable stiffness element (2) in a curved shape; and the material of the variable stiffness element (2) is a shape memory polymer. The drive control system comprises a brushless motor (1), a rotor and a UAV control board, wherein the rotors are multiple and mounted on the surface of the drive unit, the brushless motor (1) is mounted on the rotating shaft of the rotor, and the UAV control board is connected to the brushless motor (1) and the heating resistor wire (4); The shape memory polymer has a critical temperature Tg. When the temperature is lower than Tg, the material property of the shape memory polymer is rigid, and when the temperature is higher than Tg, the material property of the shape memory polymer is flexible. The UAV control board controls the on / off of the heating resistor wire (4) through a self-heating circuit. When the heating resistor wire (4) is energized, the shape memory polymer is heated, and the temperature of the shape memory polymer rises to above Tg; when the heating resistor wire (4) is de-energized, the heating of the shape memory polymer stops, and the temperature of the shape memory polymer drops to below Tg.

2. The variable stiffness foldable structure for UAV parking and obstacle avoidance in complex pipelines according to claim 1 is characterized in that: The drone body is divided into an upper layer and a lower layer. The upper layer and the lower layer share a rotor and a brushless motor (1) and are installed at a coaxial position. The upper layer and the lower layer drive parts are respectively connected to the folding parts, and the connection positions are staggered.

3. The variable stiffness foldable structure for UAV parking and obstacle avoidance in complex pipelines according to claim 2 is characterized in that: The variable stiffness element (2) and the folding portion, the variable stiffness element (2) and the driving portion, the driving portion and the rotor, the brushless motor (1) and the rotor, and the upper and lower layers of the drone body are all fixedly connected by bolts and nuts.

4. The variable stiffness foldable structure for UAV parking and obstacle avoidance in complex pipelines according to claim 1 is characterized in that: The variable stiffness element (2) is in the shape of a long strip.

5. The variable stiffness foldable structure for UAV parking and obstacle avoidance in complex pipelines according to claim 1 is characterized in that: The clamping mechanism comprises triangular saw teeth (5), and the triangular saw teeth (5) are distributed along the inner edge of the U-shaped plate.

6. The variable stiffness foldable structure for UAV parking and obstacle avoidance in complex pipelines according to claim 5 is characterized in that: The triangular saw teeth (5) are distributed parallel to the seam between the driving portion and the folding portion.

7. The variable stiffness foldable structure for UAV parking and obstacle avoidance in complex pipelines according to claim 5 is characterized in that: The material of the triangular saw teeth (5) is thermoplastic polyurethane.

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