A pneumatic adsorption device for realizing the flight of a wall-climbing robot

Abstract

The present invention discloses an aerodynamic adsorption device for realizing the flight of a wall-climbing robot, which belongs to the field of aerodynamic design; it includes a gap limiting structure, a suction cup, a motor, a propeller and a connecting seat, wherein the bottom end of the suction cup is connected to the robot body through the connecting seat; the motor is coaxially mounted on the connecting seat, and its output shaft is coaxially connected to the propeller, and the propeller is coaxially arranged in the suction cup, and the propeller disk radius is R; the gap limiting structure is a hemispherical protrusion arranged on the lip surface of the suction cup, which is used to limit the distance between the suction cup and the wall, and its axial height is 5% of the diameter of the propeller disk; the peripheral wall of the suction cup is an expansion structure from the bottom end to the lip along the axial direction; the lip is turned outward, and its axial cross-section is a convex arc segment with the center located outside the peripheral wall of the suction cup. The net adsorption force (the combined force of thrust and negative pressure) generated by the suction cup with the outward-turned arc segment lip near the wall of the present invention is nearly 50% higher than that of the straight wall type, and the lift generated in the level flight state in the air is increased by about 25%.

Description

Technical Field

[0001] The invention belongs to the field of pneumatic design, and in particular relates to a pneumatic adsorption device for realizing the flight of a wall-climbing robot. Background Art

[0002] Wall climbing robots have great research prospects in various fields, especially in dangerous work industries. After years of research, wall climbing robots have acquired multiple working modes and longer working time. However, the adsorption method they use is not well adapted to different wall materials or walls with slightly poor flatness, and some adsorption methods consume a lot of energy, while the adsorption technology using new materials is still very immature. Secondly, they are gradually being used in the field of reconnaissance. Compared with flying drones, their flexibility, obstacle crossing ability and work efficiency are slightly inferior. Therefore, it is of great significance to design a special adsorption device to give wall climbing robots stronger wall adaptability and flexible flight capabilities.

[0003] At present, the adsorption methods for wall-climbing robots generally include magnetic adsorption, vacuum adsorption, negative pressure adsorption, thrust adsorption generated by propeller rotation, and adsorption using new special materials. Among them, the magnetic adsorption method has strong adaptability to the unevenness of the wall surface and has a large adsorption force, but the principle of its adsorption force requires that the wall surface must be made of magnetic conductive material, which seriously limits the application environment of this adsorption method. The vacuum adsorption method does not have much restriction on the wall material, but it has high requirements for sealing. When the wall surface is uneven, it is easily affected by the gap and causes the suction cup attached to the wall to leak, thereby reducing the adsorption force. These methods do not enable the robot to have the ability to fly. In principle, the propeller thrust adsorption method is the closest to the aircraft, but this method consumes a lot of energy and cannot work for a long time.

[0004] In this regard, the composite adsorption device mentioned in 200810227554.X provides a solution, which uses a combination of a diversion duct, a negative pressure chamber, and a wheel. Under the combined effect of the propeller's reverse thrust and negative pressure, it ensures that the negative pressure chamber can still achieve stable adsorption with a small power when there is a certain gap with the wall surface, and has strong wall adaptability. However, it is heavy and cannot achieve stable flight of the robot. Therefore, it is necessary to improve this device to overcome the above defects.

[0005] The existing duct has a significant advantage in improving lift, but the adsorption effect is weak when attached to the wall. Using propeller thrust, top suction can be achieved at high power, but when adsorbing vertically to the wall, the effective area of ​​negative pressure on the duct is very small, making it difficult to achieve the adsorption effect. Although the suction cup used in the existing wall-moving robot using propeller thrust and negative pressure can achieve wall adsorption with low energy consumption and has strong adaptability to the wall, its utilization rate of propeller lift performance is not high, and the wall-moving robot cannot fly as easily as a general rotorcraft. Summary of the invention

[0006] Technical issues to be solved:

[0007] In order to avoid the shortcomings of the prior art, the present invention proposes an aerodynamic adsorption device for realizing the flight of a wall-climbing robot. The specially designed suction cup cooperates with the propeller to ensure that the wall-climbing robot has good adsorption performance and stable flight ability, and cooperates with the wheels on both sides of the fuselage to realize flexible wall movement. In addition, the energy utilization rate is as high as possible when realizing each function to increase the mission duration.

[0008] The technical solution of the present invention is: an aerodynamic adsorption device for realizing the flight of a wall-climbing robot, comprising a suction cup, a motor, a propeller and a connecting seat, wherein the bottom end of the suction cup is connected to the robot body through the connecting seat; the motor is coaxially mounted on the connecting seat, and its output shaft is coaxially connected to the propeller, and the propeller is coaxially arranged in the suction cup, and the propeller disk radius is R; it is characterized in that: it also includes a gap limiting structure, which is a hemispherical protrusion arranged on the lip surface of the suction cup, used to limit the distance between the suction cup and the wall, and its axial height H is 5% of the diameter of the propeller disk;

[0009] The peripheral wall of the suction cup is an expansion structure from the bottom end to the lip along the axial direction; the lip is everted, and its axial cross-section is a convex arc segment with the center located outside the peripheral wall of the suction cup.

[0010] A further technical solution of the present invention is: the radius of the bottom end surface of the suction cup is 0.996R; taking the bottom end surface of the suction cup as a reference, the axial height h of the midpoint of the paddle disc is 0.6R, and the radius d of the inner wall of the suction cup corresponding to the paddle disc height is 1.04R; the minimum gap s between the propeller tip and the inner wall of the suction cup is 2.33% of the diameter of the paddle disc; the axial height of the vertex of the suction cup lip is 0.51 times the diameter of the paddle disc, and the radius D / 2 of the circle where the vertex is located is 1.576R.

[0011] A further technical solution of the present invention is that the convex arc radius of the axial cross section of the lip is 0.3R.

[0012] A further technical solution of the present invention is: the generatrix of the suction cup peripheral wall is formed by a smooth transition of two curves, the first curve is from the bottom end surface of the suction cup to the axial height of the suction cup peripheral wall is 0.974R, where the radius of the suction cup inner wall is 1.34R; the second curve is a convex arc segment with the lip turned outward.

[0013] A further technical solution of the present invention is that the gap limiting structure is a bull's eye bearing.

[0014] A further technical solution of the present invention is: the connecting base includes a motor base and a suction cup mounting base, the motor base is located at the center; the suction cup mounting base is a semicircular ring structure, and its inner circumference is coaxially fixed to the periphery of the motor base by three common ribs arranged along the circumferential direction.

[0015] A further technical solution of the present invention is that a reinforcing rib is further arranged between the motor base and the suction cup mounting base.

[0016] A further technical solution of the present invention is: the diameter of the motor base is 0.57R, and the diameter of the disk mounting base is 0.998R.

[0017] A further technical solution of the present invention is: a mortise is provided on the peripheral surface of the bottom end of the suction cup, which corresponds to the position of the ribs on the connecting seat one by one, and is installed in cooperation with each other to achieve the fixation of the suction cup and the connecting seat.

[0018] A further technical solution of the present invention is: the axial height of the mortise is 0.09R.

[0019] Beneficial Effects

[0020] The beneficial effect of the present invention is that: the aerodynamic adsorption device for realizing the flight of the wall-climbing robot proposed by the present invention, when the rigid non-deformed gap limiting structure contacts the wall, the suction cup lip plane and the wall maintain a fixed narrow gap (i.e. 5% of the diameter of the propeller disc), the propeller rotates to generate negative pressure in the duct-like suction cup, and the pressure and the relatively small propeller thrust at this time work together to be transmitted to the fuselage wheels through the connecting seat (because the wheels are the body movement and the maximum gap limiting mechanism, and are also the main source of friction), thereby achieving wall adhesion. Compared with the technical solution of the 200810227554.X patent using negative pressure adsorption, the lip section of the present invention is an outward-turned convex arc section instead of a straight wall section. Theoretical calculation and experimental verification results show that the net adsorption force (the combined force of thrust and negative pressure) generated by the suction cup using the outward-turned arc section lip near the wall is nearly 50% higher than that of the straight wall type, and the lift generated in the level flight state in the air is about 25% higher. In addition, the suction force and lift during level flight that the suction cup can provide will increase with the increase of the radius of the lip eversion section. When the radius exceeds 0.3R, the suction force growth tends to be slow, while the lift begins to decrease.

[0021] Due to the different moving mechanism, compared with the gap limiting device mentioned in the 200810227554.X patent, the gap limiting structure in the present invention is only a small hemispherical protrusion on the suction cup lip, and in actual applications, when multiple suction cups work together, the suction cup lip plane and the wall surface can be stabilized at a fixed distance. The protrusion is in point contact with the wall surface, and the obstruction friction effect generated during movement can be ignored. Through the study of the protrusion radius, it is found that the magnitude of the adsorption force increases with the decrease of its radius until 10%R, after which the adsorption force decreases. The experiment also verified this point. When the gap is limited to 10%R, the adsorption force is the largest year-on-year.

[0022] In addition, under the interaction between the suction cup inner channel and the propeller, the tip vortex will be formed at the propeller tip due to the pressure difference between the pressure surface and the inner wall, which will cause loss of propeller aerodynamic efficiency. Therefore, compared with the solution proposed in 200810227554.X, the present invention also studies the gap between the tip and the inner wall of the suction cup to further improve the efficiency of the propeller. After simulation calculation and experiment, it is found that for the suction cup propeller combination system in this article, reducing the gap between the tip and the inner wall is an effective means to improve aerodynamic efficiency. When the gap is less than 7.5% of the propeller radius, the blade is more outstanding in terms of lift and adsorption, and the aerodynamic performance is gradually improved as the gap is reduced. However, in actual tests, it is found that when the gap is less than 2.33% of the propeller disk diameter, it is easy to cause problems such as blade beating due to blade deformation.

[0023] The experimental conclusion shows that when the lip eversion radius is 0.3R, the gap limiting structure radius is 10%R, and the gap condition is 2.33% of the diameter of the paddle disk, the robot equipped with four pneumatic adsorption devices and a set of two-wheel differential movement devices mentioned in the specific embodiment can achieve stable vertical wall adsorption with less than 10% throttle, and flexible wall movement with 15% throttle. When flying in the air, only about 40% throttle is required for stable flight. In addition, the power consumed during air flight is about 600 watts, and the power consumed during wall adsorption is about 40 watts. The power consumed during wall adsorption is only 1 / 15 of that during air flight, and the working time is greatly extended. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a front view of the structure of the pneumatic adsorption device of the present invention.

[0025] Figure 2 It is a schematic diagram of assembling the suction cup and the connecting seat of the pneumatic adsorption device of the present invention.

[0026] Figure 3 It is an axial view of the inner wall surface of the suction cup of the pneumatic adsorption device of the present invention.

[0027] Explanation of the reference numerals: 1. Gap limiting structure, 2. Outward-turned semicircular arc segment lip, 3. Mortise, 4. Connecting seat. DETAILED DESCRIPTION

[0028] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0029] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0030] Reference Figure 1 The present invention is an aerodynamic adsorption device for realizing the flight of a wall-climbing robot, comprising a gap limiting structure 1, a suction cup 2, a motor, a propeller and a connecting seat 4, wherein the bottom end of the suction cup 2 is connected to the robot body through the connecting seat 4; the motor is coaxially mounted on the connecting seat 4, and its output shaft is coaxially connected to the propeller, and the propeller is coaxially arranged in the suction cup, and the propeller disk radius of the propeller is R; the gap limiting structure 1 is a hemispherical protrusion arranged on the lip surface of the suction cup 2, which is used to limit the distance between the suction cup 2 and the wall, and its axial height H is 5% of the diameter of the propeller disk;

[0031] Reference Figure 2 , 3 As shown, the connection base 4 includes a motor base and a suction cup mounting base, and the motor base is located at the center; the suction cup mounting base is a semicircular ring structure for weight reduction, and its inner circumference is coaxially fixed to the periphery of the motor base through three common ribs and one reinforcing rib arranged along the circumference. A mortise is arranged on the circumference of the bottom end of the suction cup 2, which corresponds to the position of the common ribs and reinforcing ribs on the connection base 4, and is installed in cooperation with each other to achieve the fixation of the suction cup 2 and the connection base 4, and the axial height of the mortise is 0.09R. The diameter of the motor base is 0.57R, and the diameter of the disk mounting base is 0.998R.

[0032] The peripheral wall of the suction cup is an expansion structure from the bottom end to the lip along the axial direction; the lip is everted, and its axial cross-section is a convex arc segment with the center located outside the peripheral wall of the suction cup, and the radius of the convex arc is 0.3R.

[0033] The generatrix of the peripheral wall of the suction cup 2 is formed by a smooth transition of two curves. The first curve is from the bottom end surface of the suction cup to the axial height of the peripheral wall of the suction cup is 0.974R, where the radius of the inner wall of the suction cup is 1.34R; the second curve is a convex arc section with the lip everted.

[0034] The suction cup 2 is made of nylon material, has a duct-like shape, and has a wall thickness of 1 mm; the radius of its bottom end face is 0.996R; taking the bottom end face of the suction cup 2 as a reference, the axial height h of the midpoint of the propeller disc is 0.6R, and the radius d of the suction cup inner wall corresponding to the propeller disc height is 1.04R; the minimum gap s between the propeller tip and the inner wall of the suction cup is 2.33% of the propeller disc diameter; the axial height of the vertex of the suction cup lip is 0.51 times the diameter of the propeller disc, and the radius D / 2 of the circle where the vertex is located is 1.576R.

[0035] Example:

[0036] When the wall-climbing robot is working, the motor drives the propeller to rotate at high speed in the suction cup 2. According to the Bernoulli principle, the dynamic pressure increases and the static pressure decreases. The speed difference between the upper and lower surfaces of the blades causes the static pressure difference to appear, thereby generating thrust. Under the suction effect of the propeller, a large amount of airflow is sucked into the suction cup along the suction cup axis. The airflow velocity inside the suction cup inlet section is greatly increased, and the pressure is lower than the atmospheric pressure outside the suction cup, so that a certain negative pressure is generated inside the suction cup, thereby making the suction cup under the pressure of the atmosphere. The thrust direction is consistent with the pressure direction, so the combined force of the two is the aerodynamic force of the designed aerodynamic adsorption device.

[0037] Generally, wall-climbing robots use propeller thrust to achieve adsorption, and often use axial fans or centrifugal fans. However, this type of thrust generating device is large in size and weight, and the motor power required is generally very large. In addition, one of the goals of the present invention is to achieve the flight of the robot. Therefore, for the total weight of 450g, the rotor uses a ducted propeller commonly used in drones, a Gemfan D63 three-blade propeller, with a maximum propeller disc radius of about 31.6mm and a maximum thickness of 10mm. The motor uses the TMOTOR F1404 used with a matching 2.5-inch propeller, with a maximum power of 316W and a weight of less than 10g.

[0038] For the pneumatic adsorption device designed in the present invention, its adsorption force is a nonlinear superposition of thrust and negative pressure. When adsorbed close to the wall, if the gap between the lip and the wall is too large, the negative pressure inside the suction cup will be reduced, the adsorption performance will be reduced, and if the gap is too small, the thrust will be greatly weakened, which will also reduce the adsorption capacity. Therefore, it is necessary to determine the most suitable gap to maximize the adsorption force. In addition, since four sets of pneumatic adsorption devices are used in the overall design of the robot, and the crawling mechanism is designed as a double-wheel type, it is difficult to ensure that the gap between the four suction cups and the wall is always the same by controlling the gap between the lip and the wall by the wheels alone, which makes the adsorption force unstable. Therefore, it is necessary to add a gap limiting structure 1 to the suction cup so that the distance between each suction cup 2 and the wall is always the same. Taking into account the influence of friction, the gap limiting structure 1 finally designed after theoretical simulation calculation and experiment is a circular arc protrusion above the lip of the suction cup 2, and its maximum height is 3mm, that is, the optimal adsorption gap is 3mm.

[0039] The connecting seat 4 is made of carbon plate, including a motor base with a diameter of 18mm and a suction cup mounting base with a minimum radius of 31.537, and the motor base is riveted to the motor. Similar to the duct, the aerodynamic force that can be generated by the aerodynamic adsorption device in the present invention is also affected by the airflow conditions at the suction cup outlet, but the motor and the propeller cannot be directly fixed in the suction cup, so the motor base must be connected to the suction cup mounting base and the connection requires a certain strength. Therefore, on the basis of ensuring the air flow as much as possible, it is connected to the suction cup mounting base through three ordinary ribs and one reinforcing rib, and the ribs are assembled with the mortise reserved at the bottom of the suction cup, and the suction cup is fixed to the fuselage through the mounting base.

[0040] When the robot changes from the flight mode to the wall adsorption mode, the suction cup 2 must collide with the wall once. However, in order to ensure the weight of the entire adsorption device, the suction cup wall thickness is designed to be only 1 mm. Therefore, the suction cup is made of nylon material with good strength and toughness, and its shape is a duct-like shape that includes a propeller and a motor. For a general ducted propeller device, its aerodynamic force is mainly affected by parameters such as the duct lip radius and the blade tip-duct gap. Therefore, in order to improve the aerodynamic characteristics of the device of the present invention, a large number of theoretical calculations and experimental verifications have been carried out on these parameters. The final determined suction cup parameters are as follows: the radius of the inner wall at the bottom is 30.537 mm, and 4 corresponding mortises with a height of 3 mm are arranged at the bottom according to the thickness and position of the ribs. Taking the bottom of the suction cup as the reference, the height at the center of the propeller disc is 19 mm, and the radius of the inner wall of the duct here is 33.3 mm, that is, the minimum gap between the blade tip and the inner wall of the duct is 2.33% of the propeller disc diameter; the fixed point height of the suction cup lip is 35.572 mm, and the inner wall radius is 49.813 mm at this time; at a height of 30.764 mm, the radius of the inner wall of the suction cup is 42.4 mm, and the suction cup line from the bottom to here is a smooth curve, and continuing upward here, the suction cup forms a semicircular arc segment lip with an outward radius of 9.533 mm.

[0041] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and purpose of the present invention.

Claims

1. An aerodynamic adsorption device for realizing the flight of a wall-climbing robot, comprising a suction cup, a motor, a propeller and a connecting seat, wherein the bottom end of the suction cup is connected to the robot body through the connecting seat; the motor is coaxially mounted on the connecting seat, and its output shaft is coaxially connected to the propeller, and the propeller is coaxially arranged in the suction cup, and the propeller disc radius is R; characterized in that: It also includes a gap limiting structure, which is a hemispherical protrusion arranged on the lip surface of the suction cup, used to limit the distance between the suction cup and the wall surface, and its axial height H is 5% of the diameter of the paddle disc; The peripheral wall of the suction cup is an expansion structure from the bottom end to the lip along the axial direction; the lip is everted, and its axial cross section is a convex arc segment with the center located outside the peripheral wall of the suction cup; The radius of the bottom end surface of the suction cup is 0.996R; with the bottom end surface of the suction cup as a reference, the axial height h of the midpoint of the propeller disc is 0.6R, and the radius d of the inner wall of the suction cup corresponding to the height of the propeller disc is 1.04R; the minimum gap s between the propeller tip and the inner wall of the suction cup is 2.33% of the diameter of the propeller disc; the axial height of the vertex of the suction cup lip is 0.51 times the diameter of the propeller disc, and the radius D / 2 of the circumference of the vertex is 1.576R; The convex arc radius of the axial cross section of the lip is 0.3R; The generatrix of the suction cup peripheral wall is formed by a smooth transition of two curves. The first curve is from the bottom end surface of the suction cup to the axial height of the suction cup peripheral wall of 0.974R, where the radius of the suction cup inner wall is 1.34R; the second curve is a convex arc section with the lip everted.

2. The aerodynamic adsorption device for realizing the flight of a wall-climbing robot according to claim 1, characterized in that: The gap defining structure is a bull's eye bearing.

3. The aerodynamic adsorption device for realizing the flight of a wall-climbing robot according to claim 1, characterized in that: The connecting base includes a motor base and a suction cup mounting base, wherein the motor base is located at the center; the suction cup mounting base is a semicircular ring structure, and its inner circumference is coaxially fixed to the periphery of the motor base through three common ribs arranged along the circumferential direction.

4. The aerodynamic adsorption device for realizing the flight of a wall-climbing robot according to claim 3, characterized in that: A reinforcing rib is also arranged between the motor base and the suction cup mounting base.

5. The aerodynamic adsorption device for realizing the flight of a wall-climbing robot according to claim 3, characterized in that: The diameter of the motor base is 0.57R, and the diameter of the suction cup mounting base is 0.998R.

6. The aerodynamic adsorption device for realizing the flight of a wall-climbing robot according to claim 1, characterized in that: The bottom peripheral surface of the suction cup is provided with mortises, which correspond to the positions of the ribs on the connecting seat one by one, and are installed in coordination with each other to achieve the fixation of the suction cup and the connecting seat.

7. The aerodynamic adsorption device for realizing the flight of a wall-climbing robot according to claim 6, characterized in that: The axial height of the mortise is 0.09R.

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