Magnetic attraction crawler and crawling control method thereof

Abstract

The application relates to a magnetic attraction crawler and a crawling control method thereof, wherein the magnetic attraction crawler comprises a frame and a magnetic attraction assembly; two moving wheels are arranged at the front end of the frame, and one moving wheel is arranged at the rear end of the frame; the moving wheels at the front end are driving wheels connected with driving devices, and the driving devices are arranged in the frame; the magnetic attraction assembly comprises a first magnetic attraction structure and a second magnetic attraction structure; the first magnetic attraction structure comprises three sector-shaped electromagnetic attraction structures corresponding to the three moving wheels respectively; the radius of the sector-shaped electromagnetic attraction structure is smaller than the radius of the moving wheel; each sector-shaped electromagnetic attraction structure is coaxial with the moving wheel and is rotatably arranged on the moving wheel; the second magnetic attraction structure comprises a permanent magnet and a lifting mechanism; the permanent magnet is arranged in the middle of the frame through the lifting mechanism; and the lifting mechanism is used for adjusting the distance between the permanent magnet and the frame. The application solves the problem that the current crawler has limited wall surface scenarios in single crawling movement.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of crawlers, in particular to a magnetic attraction crawler and a crawling control method thereof. BACKGROUND

[0002] The existing wall-climbing robots are mostly single-structure and constant-attraction, which results in that they can only realize movement in specific occasions. Specifically, since the magnetic force is constant, the crawler is prone to falling when the wall magnetism is small and the crawler has too large movement resistance when the wall magnetism is large, that is, the crawler can adapt to a small range of wall magnetism. Meanwhile, the crawler is prone to falling when the wall inclination is large. In order to avoid the above problems, a larger magnetic force can be provided for the crawler, but this will result in that the crawler has too large movement resistance on the horizontal wall. Therefore, the current crawler can only crawl in a limited wall scene in a single crawling movement. Moreover, since the shape and magnetism of the crawler are fixed, the crawler cannot move on the wall with large curvature and corner.

[0003] At present, there is no effective solution to the problem that the current crawler can only crawl in a limited wall scene in a single crawling movement. SUMMARY

[0004] The present application provides a magnetic attraction crawler and a crawling control method thereof to solve the problem that the current crawler can only crawl in a limited wall scene in a single crawling movement.

[0005] In the first aspect, the present application provides a magnetic attraction crawler, comprising a vehicle frame and a magnetic attraction assembly.

[0006] The front end of the vehicle frame is provided with two moving wheels and the rear end is provided with one moving wheel. The moving wheels at the front end are driving wheels connected with driving devices, and the driving devices are installed inside the vehicle frame.

[0007] The magnetic attraction assembly comprises a first magnetic attraction structure and a second magnetic attraction structure. The first magnetic attraction structure comprises three sector-shaped electromagnetic attraction structures corresponding to the three moving wheels. The radius of the sector-shaped electromagnetic attraction structure is smaller than the radius of the moving wheel. Each sector-shaped electromagnetic attraction structure is coaxial with the moving wheel and is rotatably installed on the moving wheel. The second magnetic attraction structure comprises a lifting mechanism and a permanent magnet installed in the middle of the vehicle frame through the lifting mechanism. The lifting mechanism is used to adjust the distance between the permanent magnet and the vehicle frame.

[0008] In the second aspect, the present application provides a control method of a magnetic attraction crawler, which is used to control the attraction force of the magnetic attraction crawler when it crawls on a magnetic wall. The method comprises the following steps:

[0009] calculating a first attraction force limit value of the magnetic attraction crawler when it crawls on the magnetic wall and a second attraction force limit value :

[0010]

[0011]

[0012] wherein, G and respectively represent the gravity of the magnetic crawler and the gravity of the load thereof, and respectively represent the static friction coefficient and the rolling friction coefficient between the driving wheel and the magnetic wall surface, α represents the inclination angle of the magnetic wall surface, η represents the transmission efficiency of the speed reducer in the driving device, represents the maximum driving torque of the motor in the driving device, R represents the radius of the driving wheel;

[0013] The target adsorption force of each sector-shaped electromagnetic adsorption structure and the permanent magnet to the magnetic wall surface is set between and .

[0014] In a third aspect, the present application provides a self-adaptive crawling system, comprising the magnetic crawler and the controller thereof according to the first aspect, and the controller is configured to execute the control method of the magnetic crawler according to the second aspect.

[0015] Compared with the related art, the magnetic crawler in the present application can adjust the adsorption force of the crawler to the wall surface in real time according to the actual situation by adopting the electromagnetic-permanent magnet cooperative adsorption system. For example, the magnetic force can be increased when crawling on a wall surface with small magnetism, and the magnetic force can be reduced when crawling on a wall surface with large magnetism. Or, the magnetic force can be increased when crawling on a steep wall surface, and the magnetic force can be reduced when crawling on a horizontal wall surface. Therefore, the magnetic crawler provided in the present embodiment can adjust the adsorption force to the wall surface in real time according to the actual wall surface in a single crawling movement, so that more wall surface scenarios can be adapted, and the problem that the crawling movement of the current crawler in a single crawling movement is limited to a few wall surface scenarios is solved.

[0016] Details of one or more embodiments of the present application are presented in the following drawings and description to make other features, objects and advantages of the present application more apparent. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a structural diagram of the magnetic crawler provided in the present embodiment;

[0018] Figure 2 is a perspective structural diagram of the sector-shaped electromagnetic adsorption structure provided in the present embodiment;

[0019] Figure 3is a planar structure diagram of the fan-shaped electromagnetic adsorption structure provided in the embodiment;

[0020] Figure 4 is a structure diagram of the second magnetic adsorption structure provided in the embodiment;

[0021] Figure 5 is a structure diagram of the rotating mechanism provided in the embodiment;

[0022] Figure 6 is a force analysis diagram of the magnetic adsorption crawler provided in the embodiment;

[0023] Figure 7 is a crawling posture diagram of the magnetic adsorption crawler on a flat wall surface provided in the embodiment;

[0024] Figure 8 is a crawling flowchart of the magnetic adsorption crawler on a flat wall surface provided in the embodiment;

[0025] Figure 9 is a crawling posture diagram of the magnetic adsorption crawler on an arc-shaped wall surface provided in the embodiment;

[0026] Figure 10 is a crawling flowchart of the magnetic adsorption crawler on an arc-shaped wall surface provided in the embodiment;

[0027] Figure 11 is a crawling posture change diagram of the magnetic adsorption crawler when passing through a right-angle wall surface provided in the embodiment;

[0028] Figure 12 is a crawling flowchart of the magnetic adsorption crawler when passing through a right-angle wall surface provided in the embodiment;

[0029] Figure 13 is a crawling flowchart of the magnetic adsorption crawler when passing through a non-flat wall surface provided in the embodiment. DETAILED DESCRIPTION

[0030] In order to more clearly understand the purpose, technical solutions and advantages of the present application, the present application is described and explained below in conjunction with the drawings and embodiments.

[0031] Unless otherwise defined, technical terms or scientific terms used in the present application shall have the same meaning as those commonly understood by a person of ordinary skill in the art to which the present application belongs. The terms "one", "a", "an", "the", "these", and similar terms in the present application do not indicate quantity, and they can be singular or plural. The terms "include", "contain", "have", and any variants thereof in the present application are intended to cover non-exclusive inclusion; for example, a process, method, and system, product or device containing a series of steps or modules (units) are not limited to the listed steps or modules (units), but can include steps or modules (units) not listed, or can include other steps or modules (units) inherent to the process, method, product or device. The terms "connected", "connected", "coupled" and the like in the present application are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The term "multiple" in the present application refers to two or more. The term "and / or" describes the association between the associated objects, which means that there can be three relationships, for example, "A and / or B" can mean that A exists alone, A and B exist together, and B exists alone. Generally, the character " / " represents an "or" relationship between the associated objects. The terms "first", "second", "third" and the like in the present application are only used to distinguish similar objects, and do not represent a specific order of the objects.

[0032] A magnetic crawler is provided in the embodiment, Figure 1 is a structural diagram of the magnetic crawler provided in the embodiment, as Figure 1 The magnetic crawler includes a frame and a magnetic attraction assembly.

[0033] Two moving wheels are installed at the front end of the frame, and one moving wheel is installed at the rear end of the frame. The moving wheel at the front end is a driving wheel 13 connected with a driving device 14, and the driving device 14 is installed inside the frame.

[0034] In the embodiment, the crawler adopts a three-wheel structure. The front two wheels are driving wheels 13, which provide support force and driving force for the crawler. The rear wheel is a universal wheel, which does not provide driving force and is only used for support and adsorption. The symmetrical mechanical layout design enables the crawler to have omnidirectional movement ability while maintaining structural balance.

[0035] The driving device 14 is equipped with a double-drive differential steering system, the power core of which is driven by an integrated reduction motor, which synchronously drives the two driving wheels 13 at the front end. Flexible steering is achieved by real-time adjustment of the speed difference between the two driving wheels 13.

[0036] Referring to Figures 1 to 5The vehicle frame comprises a first frame body 11 (front vehicle body) and a second frame body 12 (rear vehicle body), the first frame body 11 is rotationally connected with the second frame body 12 through a rotating mechanism, the rotating mechanism is used for adjusting the angle of the first frame body 11 and the second frame body 12 in the direction of travel, both the driving wheels 13 and the driving device 14 are mounted on the first frame body 11, and the universal wheel is mounted on the second frame body 12. In the embodiment, the rotating mechanism comprises an angle motor 33 and a connecting shaft, the first frame body 11 and the second frame body 12 are rotationally connected through the connecting shaft, the angle motor 33 can be mounted on the first frame body 11 or the second frame body 12, and is used for controlling the rotation of the connecting shaft and thus the included angle between the first frame body 11 and the second frame body 12. Exemplarily, the first frame body 11 and the second frame body 12 are rotationally connected through the connecting shaft, one end of the connecting shaft is rotationally mounted on the first frame body 11, and the other end of the connecting shaft is fixedly connected with the second frame body 12, when the connecting shaft rotates on the first frame body 11, the second frame body 12 can be driven to rotate relative to the first frame body 11, so that the included angle between the first frame body 11 and the second frame body 12 is adjusted. Essentially, the connecting shaft constitutes a hinge mechanism. The connecting shaft is coaxially fixed with the first gear 31, the angle motor 33 is fixedly mounted on the first frame body 11, and the output shaft of the angle motor 33 is coaxially fixed with the second gear 32, the first gear 31 and the second gear 32 are engaged. When the angle motor 33 mounted on the first frame body 11 drives the first gear 31 to rotate through the second gear 32, the connecting shaft can be driven to rotate on the first frame body 11, and the second frame body 12 can be driven to rotate relative to the first frame body 11.

[0037] The magnetic attraction assembly comprises a first magnetic attraction structure and a second magnetic attraction structure; the first magnetic attraction structure comprises three sector-shaped electromagnetic attraction structures corresponding to the three moving wheels respectively, the radius of the sector-shaped electromagnetic attraction structure is smaller than the radius of the moving wheel, each sector-shaped electromagnetic attraction structure is coaxial with the moving wheel and is rotationally mounted on the moving wheel; the second magnetic attraction structure comprises a permanent magnet 24 and a lifting mechanism, the permanent magnet 24 is mounted in the middle of the vehicle frame through the lifting mechanism, and the lifting mechanism is used for adjusting the distance between the permanent magnet and the vehicle frame.

[0038] In the embodiment, the magnetic attraction crawler adopts an electromagnetic-permanent magnet cooperative attraction system, the crawler is attracted to the wall surface by magnetic attraction force, the sector-shaped electromagnetic attraction mechanism is designed on the driving wheel and the universal wheel, the sector-shaped electromagnetic attraction mechanism can be actively rotated, the permanent magnet is mounted at the bottom of the crawler, and the permanent magnet block can also be lifted.

[0039] Please refer to Figure 2 and Figure 3The fan-shaped electromagnetic adsorption structure comprises a fan-shaped mounting shell 211 and a plurality of columnar electromagnetic actuating units 212, the plurality of columnar electromagnetic actuating units 212 are uniformly mounted in the fan-shaped mounting shell 211 along the direction of the circular arc of the fan-shaped mounting shell 211, and the axis of the columnar electromagnetic actuating unit 212 is orthogonal to the radial line of the fan-shaped mounting shell 211. Figure 1 The first magnetic adsorption structure further comprises a micro motor 22 and a driving shaft, the driving shaft is coaxial with the moving wheel and is rotatably mounted on the moving wheel, the micro motor 22 is fixed on one side of the moving wheel through a connecting rod 23 and is used to provide a rotating driving force to the driving shaft, and the fan-shaped electromagnetic adsorption mechanism is mounted on the driving shaft. When the micro motor 22 works, the fan-shaped electromagnetic adsorption mechanism can be driven by the driving shaft to rotate relative to the moving wheel on the moving wheel, so as to adjust the direction of the adsorption force. Exemplarily, the moving wheel can be provided with an inner cavity, and the fan-shaped electromagnetic adsorption structure is arranged in the inner cavity. In addition, the moving wheel can be provided with a mounting area on one side, and the fan-shaped electromagnetic adsorption structure is arranged in the mounting area.

[0040] Exemplarily, the moving wheel can be provided with an inner cavity, and the fan-shaped electromagnetic adsorption structure is arranged in the inner cavity. In addition, the moving wheel can be provided with a mounting area on one side, and the fan-shaped electromagnetic adsorption structure is arranged in the mounting area. Figure 4 The lifting mechanism comprises a lifting motor 252, a ball screw 251 and a limiting rod 253, the lifting motor 252 is used to drive the ball screw 251 to rotate, the permanent magnet 24 is mounted on the ball screw 251, and the limiting rod 253 is parallel to the ball screw 251 and slidably penetrates the permanent magnet 24, and is used to limit the rotation of the permanent magnet 24, so that the permanent magnet 24 can be driven to move up and down when the ball screw 251 rotates.

[0041] In summary, the electromagnetic-permanent magnet cooperative adsorption system adopted by the magnetic adsorption crawler in the embodiment has the following characteristics:

[0042] 1. A dual-mode design of active electromagnetic driving and passive magnetic swinging is adopted, an innovative sectorized magnetic pole array design is adopted, three groups of columnar electromagnetic actuating units are arranged along the sector contour, the matching of the magnetic pole structure and the sector geometry is realized, the central axis is orthogonal to the radial reference line of the sector, and the spatial arrangement can generate a composite magnetic field distribution with gradient characteristics through the phase superposition of the magnetic pole vectors. The fan-shaped electromagnetic adsorption structure can be actively adjusted in direction and size through motor control, and if the motor does not work, the fan-shaped electromagnetic adsorption structure can also be passively swung through the magnetism of the wall surface.

[0043] Specifically, the structure realizes concentrated output and local reinforcement of magnetic force by integrating multiple cylindrical electromagnets in a single sector area of the wheel, improves adhesion stability and adsorption efficiency, and has the advantages of compact structure, flexible regulation, strong adaptability, etc. Three cylindrical electromagnet units are arranged side by side in the sector installation area; each electromagnet unit includes a cylindrical core and a surrounding coil structure; the cylindrical electromagnets can be electrically connected to the electromagnetic control system to realize independent adjustment of the adsorption force; the sector area faces the outer wall. The three cylindrical electromagnets are symmetrically arranged along the arc direction of the sector area and close to the inner wall of the rim; magnetic isolation structures or non-magnetic materials are provided between the electromagnets to reduce magnetic flux interference; the rim body is made of non-magnetic high-strength material to ensure that the magnetic flux is concentrated and output to the wall surface; the electromagnetic control system can independently control the on-off, current size and working time sequence of each electromagnet. The comparison between the sector electromagnetic adsorption mechanism and the common rectangular electromagnet block is shown in the following table:

[0044] Table 1 Comparison between sector electromagnetic adsorption mechanism and rectangular electromagnet block

[0045]

[0046] As can be seen from Table 1, the advantages of the sector electromagnetic adsorption mechanism are as follows:

[0047] More flexible control: Multiple cylindrical electromagnets can be controlled by independent circuits to realize multi-stage magnetism adjustment, adsorption logic optimization, dynamic switching and other functions, and adapt to different wall climbing postures and complex wall surfaces. The rectangular electromagnet structure is excited as a whole and cannot realize local control and intelligent management of adsorption rhythm.

[0048] Better heat management performance: The present application uses a distributed small-power electromagnet combination, with short heat dissipation path and uniform heat source distribution, making it easier to control the overall heat generation and conducive to long-term stable operation of the system. In contrast, the heat is concentrated in a single rectangular electromagnet structure, and long-time energization may cause local overheating of the magnetic core, affecting the adsorption performance.

[0049] Higher space utilization efficiency: The cylindrical electromagnets are arranged in an arc shape and embedded in the sector area, with a geometry that better fits the edge of the wheel, maximizing the use of limited space. Rectangular block-shaped electromagnets often produce dead angles when arranged in the circular edge area, resulting in wasted space or structural interference.

[0050] Stronger ability to adapt to complex wall surfaces: When encountering uneven wall surfaces, local obstacles or holes, a part of the multiple cylindrical electromagnets can still be independently adsorbed to maintain the adhesion of the crawler; while the rectangular electromagnet is a whole adsorption structure, once part of the area cannot be tightly attached, the overall adsorption force will be significantly reduced.

[0051] 2. The device bottom carries a modular permanent magnetic adsorption body, which adopts a combination of precision ball screw and motor, realizes the vertical lifting of the permanent magnet block through the screw nut pair, so as to adjust the adsorption force.

[0052] 3. The universal wheel does not provide driving force here, and plays a supporting and adsorbing role, and the structure design peels off the power transmission, realizes 360° free steering. A fan-shaped electromagnetic adsorption structure is controlled by a motor, so that the direction and size of the magnetic field can be actively adjusted, and more stable adsorption force and supporting force are provided.

[0053] Therefore, the core of the electromagnetic-permanent magnetic cooperative adsorption system is to combine the high transmission efficiency (small friction loss and high positioning accuracy) of the ball screw and the precise pulse control ability of the motor, so as to adjust the magnetic adsorption force and the action range in real time according to the demand. For example, in the magnetic adsorption wall climbing robot, by adjusting the distance between the permanent magnet and the wall, the strong magnetic adsorption force can be guaranteed, and the adaptive adsorption and stable operation of the complex curved surface (such as the surface of the weld and rivet) can be realized.

[0054] In summary, the magnetic adsorption crawler in the embodiment can adjust the adsorption force of the crawler to the wall in real time according to the actual situation through the electromagnetic-permanent magnetic cooperative adsorption system. For example, the magnetic force can be increased when climbing a wall with small magnetism, and the magnetic force can be reduced when climbing a wall with large magnetism. Or, the magnetic force can be increased when climbing a steep wall, and the magnetic force can be reduced when climbing a horizontal wall. Therefore, the magnetic adsorption crawler provided in the embodiment can adjust the adsorption force to the wall in real time in a single crawling movement, so as to adapt to more wall scenarios, and solve the problem that the current crawler can only crawl in a limited wall scenario in a single crawling movement.

[0055] In order to better realize the movement of the crawler, the crawler is also integrated with the following sensors:

[0056] The ultrasonic thickness gauge is installed at the front end of the chassis (on the first frame), which contacts the measured surface to collect the thickness of the wall in real time.

[0057] The ultrasonic distance meter is installed at the rear end of the chassis (on the second frame), which measures the distance between the bottom surface of the permanent magnet and the wall.

[0058] The inductive sensor is installed at the front end of the crawler (on the first frame), which is used to detect the magnetic conductivity of the wall to assist in judging the magnetic conductivity of the material.

[0059] The laser profile sensor is installed at the front, middle and rear parts of the chassis (on the first frame and the second frame), which measures the bending degree of the wall to generate a three-dimensional profile (height, width, curvature, etc.) of the object in real time.

[0060] The data measured by the above sensors can be used for the movement control of the crawler. For example, when the thickness and magnetic conductive characteristics of the wall surface and the distance between the permanent magnet and the wall surface are measured, the adsorption force of the permanent magnet to the wall surface and the adsorption force of the fan-shaped electromagnetic adsorption structure to the wall surface (the distance between the fan-shaped electromagnetic adsorption structure and the wall surface is known) can be calculated.

[0061] Based on the above magnetic adsorption crawler, a control method of the magnetic adsorption crawler is also provided in the embodiment. The control method mainly includes two parts, one is to control the adsorption force of the magnetic adsorption crawler when it crawls on the magnetic wall surface, and the other is to control the included angle between the first frame body and the second frame body in the magnetic adsorption crawler through the rotating mechanism.

[0062] For the first part, it includes steps S110 to S150.

[0063] Step S110, calculating the first adsorption force limit value of the magnetic adsorption crawler when it crawls on the magnetic wall surface

[0064]

[0065] wherein, G represents the gravity of the magnetic adsorption crawler, represents the gravity of the load of the magnetic adsorption crawler, represents the static friction coefficient between the driving wheel and the magnetic wall surface, α represents the inclination angle of the magnetic wall surface.

[0066] Please refer to Figure 6 , the first adsorption force limit value is the minimum adsorption force of each magnetic adsorption unit (fan-shaped electromagnetic adsorption structure or permanent magnet) to the wall surface. To keep the crawler stable on the wall surface without sliding down, the following conditions need to be met:

[0067]

[0068] By combining the above formulas, we can get:

[0069]

[0070] The conditions that need to be met by the adsorption force provided by each magnetic adsorption unit are:

[0071]

[0072] Step S120, calculating the second adsorption force limit value of the magnetic adsorption crawler when it crawls on the magnetic wall surface

[0073]

[0074] wherein, η ​​represents the transmission efficiency of the speed reducer in the driving device, represents the maximum driving torque of the motor in the driving device, G represents the gravity of the magnetic attraction crawler, represents the gravity of the load of the magnetic attraction crawler, R represents the radius of the driving wheel, represents the rolling friction coefficient between the driving wheel and the magnetic wall surface, α represents the inclination angle of the magnetic wall surface.

[0075] Meanwhile, considering that the greater the adsorption force is, the greater the friction between the crawler and the wall surface is, and the greater driving force the driving device needs to provide, however, the driving force of the driving device has an upper limit, it is necessary to limit the upper limit value of the adsorption force. The second adsorption force limit value is the maximum adsorption force of each magnetic adsorption unit (the fan-shaped electromagnetic adsorption structure or the permanent magnet) to the wall surface.

[0076] Specifically, the adsorption force of each magnetic adsorption unit is introduced into the motor torque expression After that, the driving torque required to be provided by each motor is:

[0077]

[0078] Then, the calculation is:

[0079]

[0080] Therefore, the second adsorption force limit value is:

[0081]

[0082] Step S130, set the target adsorption force of each fan-shaped electromagnetic adsorption structure and the permanent magnet to the magnetic wall surface between the first adsorption force limit value and the second adsorption force limit value.

[0083] Controlling the adsorption force of each magnetic adsorption unit to the wall surface between the first adsorption force limit value and the second adsorption force limit value can ensure that the crawler will not fall off, and at the same time, will not hinder the crawler from advancing. Therefore, the target adsorption force of each fan-shaped electromagnetic adsorption structure to the magnetic wall surface is set between the first adsorption force limit value and the second adsorption force limit value.

[0084] Step S140, control the power of the fan-shaped electromagnetic adsorption structure according to the target adsorption force of the fan-shaped electromagnetic adsorption structure to the magnetic wall surface.

[0085] For the fan-shaped electromagnetic adsorption structure, the power thereof can be controlled to adjust the adsorption force of the fan-shaped electromagnetic adsorption structure to the wall surface. Specifically, for the electromagnet in the fan-shaped electromagnetic adsorption structure, the factors affecting the magnetic force of the electromagnet mainly include four aspects, i.e., the number of turns of the coil wound on the core, the intensity of the current in the coil, the distance between the wound coil and the core, and the size and shape of the core. The magnetic field direction is determined by the current direction and the winding direction of the coil, and follows the right-hand screw rule. If the magnetic induction intensity B is uniformly distributed along the surface of the magnetic pole, the basic formula for calculating the electromagnetic adsorption force is:

[0086]

[0087] wherein, F represents the adsorption force (unit: Newton, N); B represents the magnetic induction intensity in the air gap (unit: Tesla, T); A represents the effective area of the magnetic pole (unit: square meter, m²); represents the vacuum permeability (4π×10 -7 H / m).

[0088] Magnetic induction intensity B The magnetic induction intensity can be derived by the magnetic circuit Ohm's law:

[0089]

[0090] wherein, μ represents the permeability of the magnetic circuit material (unit: H / m, that of the core), N represents the number of turns of the coil, I represents the coil current (unit: ampere, A), l represents the total length of the magnetic circuit (including the core and the air gap, unit: meter, m).

[0091] Substituting the adsorption force formula can obtain:

[0092]

[0093] In step S150, the distance between the permanent magnet and the magnetic wall surface is controlled by the lifting mechanism according to the target adsorption force of the permanent magnet to the magnetic wall surface.

[0094] For the permanent magnet, the distance between the permanent magnet and the ground can be controlled to adjust the adsorption force of the permanent magnet to the wall surface.

[0095] For the second part, it includes: according to the target included angle, adopting a PID closed-loop control strategy to control the included angle between the first frame body and the second frame body to tend to the target included angle.

[0096] The PID closed-loop control strategy specifically includes:

[0097]

[0098] wherein, , and are PID control parameters, denotes the target angle, denotes the angle between the first frame and the second frame at time t, denotes the angle difference at time t, denotes the control signal of the motor.

[0099] The controller collects the encoder angle feedback in real time , dynamically updates the error, and controls until .

[0100] When the magnetic crawler passes through the bending part of the magnetic wall surface, the calculation formula of the target angle is:

[0101]

[0102] wherein, denotes the target angle, n 1 and n 2 are the unit normal vectors of the magnetic wall surfaces on both sides of the bending part, respectively.

[0103] When the magnetic crawler passes through the bending part of the magnetic wall surface, the calculation formula of the target angle is:

[0104]

[0105] wherein, denotes the target angle (target angle), ds denotes the forward distance of the first frame per unit time, R denotes the radius of curvature of the bending part of the magnetic wall surface.

[0106] Specifically, the angle control of the crawler in some common scenarios is as follows:

[0107] 1. Perpendicular connection:

[0108] Wall surface → top surface, the connecting shaft rotates clockwise +90°;

[0109] Wall surface → ground, the connecting shaft rotates counterclockwise -90°.

[0110] The angle between the two wall surfaces is 90°, and the connecting shaft should rotate about 90° to make the rear vehicle body parallel to the new wall surface.

[0111] 2. Inclined angle connection:

[0112] The wall angle is α, 0° < α < 180°, the connecting shaft should rotate 180°- α to compensate the angle to maintain the overall adhesion state of the crawler.

[0113] If the wall angle is 120° (obtuse angle), the connecting shaft needs to rotate 60°;

[0114] If the angle is 60° (acute angle), it needs to rotate 120°.

[0115] 3. Plane-arc surface:

[0116] The wall curvature is continuous and smooth, the central angle gradually changes, and dynamic and continuous small angle adjustment needs to be realized; the angle increment is synchronized with the change of the wall tangent direction; the connecting shaft angle adjustment range is usually fine-tuned within ± 15°~± 45°.

[0117] 4. Plane-arc surface:

[0118] The arc surface tangent angle and the plane angle need to be dynamically calculated. The final rotation angle is equal to the tangent direction of the arc surface end and the angle of the plane, which is generally 45°~90°.

[0119] In summary, the embodiment provides a magnetic attraction crawler and a control method thereof. Based on the above magnetic attraction crawler and control method, some crawling process examples of the magnetic attraction crawler are provided as follows.

[0120] Referring to Figure 7 , which is the crawling posture of the crawler on a flat wall. Referring to Figure 8 , which is the crawling process of the crawler on a flat wall: the crawler is placed on the wall; the inductive sensor detects the magnetic permeability of the wall and transmits the information to the control system, which processes the data and controls the fan-shaped electromagnet block, adjusts the adhesion force of the fan-shaped electromagnet block in combination with the material database; the ultrasonic thickness gauge measures the wall thickness and transmits the data to the roller screw, which lifts and finds the appropriate permanent magnet block adhesion force; it is judged whether the crawler can be adsorbed, yes, the crawler crawls normally on the plane, otherwise return to the step of adjusting the adhesion force of the fan-shaped electromagnet block.

[0121] Referring to Figure 9 , which is the crawling posture of the crawler on an arc-shaped wall. Referring to Figure 10 , which is the crawling process of the crawler on an arc-shaped wall: the crawler device crawls on the plane; the laser profile sensor measures the wall curvature; it is judged whether the wall has an arc, yes, the laser profile sensor transmits the wall curvature information to the control system, which processes the data and controls the fan-shaped electromagnet block, adjusts the electromagnetic adhesion force and angle according to the curvature radius and other data, otherwise returns to the previous step; the ultrasonic distance meter of the chassis measures the gap distance between the wall and the permanent magnet block, the ball screw lifts and adjusts the appropriate permanent magnet block adhesion force; the hinged mechanism actively adjusts the rotation shaft angle to prevent interference between the vehicle body and the wall, so that the device is in a stable state.

[0122] Referring toFigure 11 which is the change of the crawling posture of the crawler when passing through the right-angle wall surface. In Figure 11 , four postures of the crawler are shown, and the change of the postures is in the order of: the left-up posture, the right-up posture, the left-down posture, and the right-down posture. Specifically, when the front end of the crawler contacts the right-angle wall surface, the magnetic permeability detection sensor carried thereby starts a real-time detection program, and obtains the magnetic permeability characteristic parameter of the wall surface material through the electromagnetic induction principle. Based on the detection data, the fan-shaped electromagnet block (fan-shaped electromagnetic adsorption structure) built in the driving wheel performs dynamic vector control, the fan-shaped magnetic pole adjusts the direction, and the main direction of the magnetic field strength is adjusted to the vertical direction of the wall surface. And according to the magnetic permeability of this wall surface, the magnetic field size is adjusted so that it can generate sufficient wall adsorption force. In this way, through the driving force generated by the friction force, the robot can realize crawling along the wall surface. When it is desired to complete the transition between surfaces (there is an included angle between the two surfaces). When it is still in the previous surface, the axis of the fan-shaped electromagnet block is always perpendicular to the horizontal plane, as shown in the left-up posture in Figure 11 ; when the moving wheel (driving wheel) at the front end encounters the next surface, the fan-shaped electromagnet block senses the existence of magnetism, and immediately changes direction under the control of the motor. At this time, the axis of the fan-shaped electromagnet block on the moving wheel at the front end is perpendicular to the vertical plane, as shown in the right-up posture in Figure 11 ; at this time, the driving wheel moves forward along the vertical plane under the action of the motor and the fan-shaped electromagnet block, and the universal wheel is still in the horizontal plane. At this time, the hinge mechanism (connecting shaft) adjusts the body angle under the control of the motor, so that the crawler is in a stable state. Under the control of the motor, the axis of the fan-shaped electromagnet block on the moving wheel (universal wheel) at the rear end is perpendicular to the horizontal plane, as shown in the left-down posture in Figure 11 ; when the universal wheel encounters the next surface, the fan-shaped electromagnet block senses the existence of magnetism, and immediately changes direction under the control of the motor. At this time, the axis of the fan-shaped electromagnet block on the universal wheel is perpendicular to the vertical plane. Finally, the universal wheel also successfully transitions, and the whole crawler transitions successfully, as shown in the right-down posture in Figure 11 . During the transition, the permanent magnet block of the chassis also rises and falls under the action of the ball screw, and the adsorption force is in dynamic balance.

[0123] Referring to Figure 12 and Figure 13 , Figure 12 is the crawling process of the crawler passing through the right-angle wall surface, Figure 13The flow chart of the magnetic attraction crawler when passing through the uneven wall surface: the crawler device crawls on the plane; whether the driving wheel contacts the right-angle wall surface, the magnetic permeability detection sensor is started, the fan-shaped electromagnetic array built-in the driving wheel executes dynamic vector control, adjusts the main direction of the magnetic field to the vertical direction of the wall surface, adjusts the magnetic field size according to the magnetic permeability of the wall surface, so that it can generate sufficient wall surface adsorption force, otherwise return to the previous step; the driving wheel rolls along the wall surface, the front vehicle body is lifted, and the vehicle body is driven to climb upward; the hinged mechanism actively adjusts the rotation shaft angle to prevent the vehicle body and the wall surface from interfering, so that the device is in a stable state; the ultrasonic range finder of the chassis measures the gap distance between the wall surface and the permanent magnet block, the ball screw is lifted, and the appropriate permanent magnet block adsorption force is adjusted; the crawler realizes the transition between the plane and the plane.

[0124] In summary, the control method of the magnetic attraction crawler provided in the embodiment further includes: when the magnetic attraction crawler sequentially passes through the first wall surface and the second wall surface with an included angle, and any moving wheel simultaneously contacts the first wall surface and the second wall surface, the magnetic field intensity direction of the fan-shaped electromagnetic adsorption structure is adjusted from being perpendicular to the first wall surface to being perpendicular to the second wall surface.

[0125] It should be understood that the specific embodiments described herein are merely used to explain this application, but not to limit it. According to the embodiments provided in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor are within the scope of protection of the present application.

[0126] Obviously, the drawings are only some examples or embodiments of the present application, and those skilled in the art can also apply the present application to other similar situations without creative labor. In addition, it can be understood that although the work done in the development process may be complex and long, some design, manufacture or production changes made by those skilled in the art according to the technical content disclosed in the present application are only routine technical means and should not be regarded as insufficient disclosure of the present application.

Claims

1. A control method for a magnetic crawler, characterized in that, The magnetic crawler includes a frame and a magnetic assembly. The frame has two movable wheels at the front and one at the rear. The front wheels are drive wheels connected to a drive unit, which is installed inside the frame. The magnetic assembly includes a first magnetic structure and a second magnetic structure. The first magnetic structure includes three fan-shaped electromagnetic adsorption structures corresponding to the three movable wheels. The radius of each fan-shaped electromagnetic adsorption structure is smaller than the radius of the movable wheel, and each fan-shaped electromagnetic adsorption structure is coaxially and rotatably mounted on the movable wheel. The second magnetic structure includes a lifting mechanism and a permanent magnet mounted in the middle of the frame via the lifting mechanism. The control method includes: Calculate the first adhesion force limit of the magnetic crawler when it crawls on a magnetic wall. Second Adsorption Force Limit : ； ； in, G and These represent the gravity of the magnetic crawler and the gravity of its load, respectively. and These represent the static friction coefficient and the rolling friction coefficient between the drive wheel and the magnetic wall, respectively. α Indicates the tilt angle of the magnetic wall. η This indicates the transmission efficiency of the reducer in the drive unit. This indicates the maximum driving torque of the motor in the drive unit. R Indicates the radius of the drive wheel; The target attraction force of each sector-shaped electromagnetic adsorption structure and the permanent magnet on the magnetic wall is set at... and between.

2. The control method for the magnetic crawler according to claim 1, characterized in that, Also includes: The power of the sector-shaped electromagnetic adsorption structure is controlled based on the target adsorption force of the sector-shaped electromagnetic adsorption structure on the magnetic wall surface. The distance between the permanent magnet and the magnetic wall is controlled by a lifting mechanism based on the target attraction force of the permanent magnet on the magnetic wall.

3. The control method for the magnetic crawler according to claim 1, characterized in that, In the magnetic crawler, the rear movable wheel is a universal wheel, and the frame includes a first frame and a second frame. The first frame is rotatably connected to the second frame through a rotating mechanism. The rotating mechanism is used to adjust the angle between the first frame and the second frame in the direction of travel. Two drive wheels are installed on the first frame, and the universal wheel is installed on the second frame. The control method further includes: The angle between the first frame and the second frame is controlled by a rotating mechanism.

4. The control method for the magnetic crawler according to claim 3, characterized in that, The control of the angle between the first frame and the second frame via the rotating mechanism includes: Based on the target angle, a PID closed-loop control strategy is used to control the angle between the first frame and the second frame to tend towards the target angle.

5. The control method for the magnetic crawler according to claim 4, characterized in that, When the magnetic crawler passes through the bend in the magnetic wall, the formula for calculating the target angle is: ； in, Indicates the included angle of the target. n 1 and n 2 are the unit normal vectors of the magnetic walls on both sides of the bend.

6. The control method for the magnetic crawler according to claim 4, characterized in that, When the magnetic crawler passes through the bend in the magnetic wall, the formula for calculating the target angle is: ； in, Indicates the included angle of the target. ds This indicates the distance the first structure travels per unit of time. R This represents the radius of curvature at the bend in the magnetic wall.

7. The control method for the magnetic crawler according to claim 1, characterized in that, In the magnetic crawler, the fan-shaped electromagnetic adsorption structure includes a fan-shaped mounting shell and multiple columnar electromagnetic actuation units. The multiple columnar electromagnetic actuation units are uniformly installed inside the fan-shaped mounting shell along the arc direction of the fan-shaped mounting shell, and the axis of the columnar electromagnetic actuation unit is orthogonal to the radial line of the fan-shaped mounting shell.

8. The control method for the magnetic crawler according to claim 1, characterized in that, In the magnetic crawler, the first magnetic structure also includes a micro motor and a drive shaft. The drive shaft is coaxial with the moving wheel and rotatably mounted on the moving wheel. The micro motor is fixedly mounted on one side of the moving wheel and is used to provide rotational driving force to the drive shaft. The fan-shaped electromagnetic adsorption mechanism is mounted on the drive shaft.

9. The control method for the magnetic crawler according to any one of claims 1-8, characterized in that, The control method further includes: As the magnetic crawler passes sequentially over the first and second walls with an angle, when any of the moving wheels simultaneously contacts the first and second walls, the direction of the magnetic field strength of the control sector electromagnetic adsorption structure is adjusted from being perpendicular to the first wall to being perpendicular to the second wall.

10. An adaptive crawling system, characterized in that, Includes the magnetic crawler and its controller as described in claim 1; The controller is used to execute the control method of the magnetic crawler as described in claim 1.

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