A Novel Actuator System Combining Mechanical Vibration and Magnetic Wheels Capable of Rotational Motion Using Shape Memory Alloy Coils

Transcription

1 s Article A Novel Actuator System Combining Mechanical Vibration and Magnetic Wheels Capable Rotational Motion Using Shape Memory Alloy Coils Hiroyuki Yaguchi *, Izuru Kimura and Shun Sakuma Faculty Engineering, Tohoku Gakuin University, , Chuo, Tagajo, Japan; icchan.social-upheaval@ezweb.ne.jp (I.K.); ssakuma_1206@yahoo.co.jp (S.S.) * Correspondence: yaguchi@mail.tohoku-gakuin.ac.jp Received: 6 December 2018; Accepted: 29 December 2018; Published: 4 January 2019 Abstract: In every country, large steel bridges, such as cable-stayed bridges, are actively being constructed, and number such bridges has been progressively increasing. These bridges are ten inspected using drones, but inspection techniques have not been established because strong winds and thunder. Therefore, robots capable working in difficult environments are desired. In present study, a prototype a rotary system combining two iron disks and two electromagnetic-vibration-type s was fabricated. A new operation principle was developed that drives system using reaction force vibration-type. Two shape memory alloy coils and two friction pads were integrated into system to enable it to carry out turning operations, which were successfully demonstrated. The proposed system can thus move in any direction. In addition, with this system, both slide-on-ceiling and wall-climbing motions are possible. Keywords: system; magnetic wheel; electromagnetic vibration; shape memory alloy coil; slide-on-ceiling motion 1. Introduction In every country, large steel bridges, such as cable-stayed bridges, are actively being constructed, and number such bridges has been progressively increasing. These large structures are subjected to a surface inspection once every five years. At present, inspections large bridges with spans over 200 m are conducted by combining elevated work vehicles and telephoto vision. Furrmore, it is necessary to regularly inspect large iron tanks with outer diameters over 100 m. These inspections are made possible by building scaffolds for such large tanks. However, re are problems with current inspection methods in that microcracks cannot be reliably detected. Inspections using drones have also been conducted, but inspection techniques have not been established because strong winds and thunder. Therefore, on basis above considerations, robots capable working in difficult environments are desired. Previously proposed adhesion methods for wall surface movement include following: a permanent magnetic adhesion system [1,2], adhesive force generated by a suction cup [3] or flexible rubber [4 8], controlling attractive force an electromagnet [9], a permanent magnet combined with an iron wheel [10 13], negative pressure a pump [14,15], wind force produced by a propeller [16], vibration many caps [17,18], a claw gripper [19 21], and adhesive materials [22,23]. However, se methods involve complicated mechanisms and require adhered device to have a relatively large weight. The authors have previously proposed a magnetic capable moving on a magnetic structure by coupling a magnetic force and mechanical Actuators 2019, 8, 4; doi: /act

2 Actuators 2019, 8, resonance [24,25]. This magnetic has a simple structure and is inexpensive to manufacture. However, this is limited to movement in one direction, and cannot move if re is rust or corrosion on surface target structure. In present study, a prototype a rotary system combining two iron disks and two electromagnetic-vibration-type s was fabricated. A new operation principle was developed in which system is driven by reaction force vibration-type. Two shape memory alloy (SMA) coils and two friction pads were integrated into system to achieve rotational motion. This system was demonstrated to be capable turning operations. This magnetic-wheel-type system is able to climb upward at a speed 24 mm/s while pulling a load mass 120 g when attractive force rubber magnet is 1.78 N, and can realize both slide-on-ceiling and wall-climbing motions. The system was confirmed to be able to move on a magnetic substance, such as an iron rail, supplied by only a function generator and a power amplifier. 2. Structure Vibration-Type Actuator and Actuator System 1 shows a diagram developed vibration-type capable moving on a magnetic substance. The vibration-type consists a cylindrical permanent magnet, a translational spring, an electromagnet with an iron core, a triangular acrylic frame, and a rubber permanent magnet attached to bottom frame. The cylindrical permanent magnet is composed NdFeB and is magnetized in axial direction. It has an outer diameter 12 mm and a thickness 5 mm. The surface magnetic flux density measured by a Tesla meter was 322 mt. The translational spring is a stainless steel compression coil with an outer diameter 11 mm, a free length 18 mm, and a spring constant k 2178 N/m. The vibration component consists translational spring and cylindrical permanent magnet, and electromagnet is inserted into translational spring. The rubber permanent magnet is magnetized in thickness direction and has a length 9 mm, a width 15 mm, and a thickness 2.8 mm. The average surface magnetic flux density measured by a Tesla meter was 116 mt. The angle α mass-spring model was set to 60 based on results obtained in a previous study [24]. The has a height 42 mm, a width 15 mm, and a total mass 13.5 g. The attractive force generated by flexible rubber magnet attached at support part acts on when it is placed on a magnetic structure, as shown in 2. The frictional force between flexible magnet and magnetic substance alternates periodically during vibration. Since horizontal component inertial force exceeds frictional force, vibration-type is propelled by difference between frictional forces in forward and backward directions acting on flexible rubber magnet in support, as shown in a previous study [25]. First, Actuators movement 2019, 8, x characteristics this vibration-type were examined Structure vibration-type.

3 Actuators 2019, 8, Structure vibration-type Principle linear locomotion. An iron rail 50 mm in width, 50 mm in thickness, and 400 mm in length was used as 3 shows relationship between power input to electromagnet and speed target magnetic structure. The vibration component vibration-type was driven at vertical upward movement when mass loaded on was set to 50 and 100 g. resonance frequency using a function signal generator and an amplifier. The resonance frequency 4 shows relationship between tilt angle α iron rail and speed at was 97 Hz. The coefficient friction between iron rail and flexible magnet measured in input powers 100 and 150 mw. From se results, considering size and weight system, experiment was The attractive force F flexible magnet measured using a force gauge was this vibration-type shows good movement characteristics. However, vibration-type 1.78 N. The coefficient friction and attractive force F were fixed during experiment. is capable movement in only one direction, and to inspect state a target structure, it 3 shows relationship between power input to electromagnet and speed is necessary to move in all directions. As described above, vibration-type realizes vertical upward movement when mass loaded on was set to 50 and 100 g. unidirectional movement by periodically changing frictional force rubber magnet adhered 4 shows relationship between tilt angle α iron rail and speed at to support portion. This means that movement characteristics are also input powers 100 and 150 mw. From se results, considering size and weight system, dependent on rust and corrosion conditions surface target iron structure. this vibration-type shows good movement characteristics. However, vibration-type is capable movement in only one direction, and to inspect state a target structure, it is necessary to move in all directions. As described above, vibration-type realizes unidirectional movement by periodically changing frictional force rubber magnet adhered to support portion. This means that movement characteristics are also dependent on Actuators rust 2019, and 8, x corrosion conditions surface target iron structure Speed upward motion plotted against input power for two different load masses.

4 Actuators 2019, 8, Speed upward motion plotted against input power for two different load masses Speed Speed upward upward motion motion plotted plotted against against tilt tilt angle angle for for two two different different input input powers. powers. In present study, a new system capable movement on a magnetic surface was In present study, new system capable movement on magnetic surface was developed. 5 shows proposed rotary system, which combines a magnetic developed. 5 shows proposed rotary system, which combines a magnetic wheel, wheel, composed two iron disks and an electromagnet, with electromagnetic-vibration-type composed two iron disks and an electromagnet, with electromagnetic-vibration-type.. The system consists two electromagnetic-vibration-type s, labeled A The system consists two electromagnetic-vibration-type s, labeled A and B; an and B; an E-shaped acrylic material; four magnetic rings; an acrylic shaft; and two iron disks. E-shaped acrylic material; four magnetic rings; an acrylic shaft; and two iron disks. Electromagnetic-vibration-type s A and B are held by E-shaped acrylic frame and rotate Electromagnetic-vibration-type s and are held by E-shaped acrylic frame and rotate two iron disks using reaction force vibration-type. In this system, two iron disks using reaction force vibration-type. In this system, magnetic paths are formed by magnetic wheels, electromagnets, and iron structures. Furrmore, magnetic paths are formed by magnetic wheels, electromagnets, and iron structures. because frictional force between iron disk and rubber magnet vibration-type Furrmore, because frictional force between iron disk and rubber magnet can be kept constant, frictional force during rotational movement system on vibration-type can be kept constant, frictional force during rotational movement structure does not change. 6 shows a photograph magnetic system and parts system on structure does not change. 6 shows a photograph magnetic Actuators and assembly. 2019, system 8, x and parts and assembly In production a prototype magnetic-wheel-type system, two vibration-type s with same driving frequency and moving characteristics were produced. The E-shaped acrylic frame was made from a 1 mm-thick flat plate using a three-dimensional (3D) processing machine. The dimensions E-shaped frame in this figure correspond to iron disks 40 mm in diameter. 5. Structure magnetic-wheel-type system.

5 Actuators 2019, 8, Structure magnetic-wheel-type system Photograph Photograph magnetic magnetic system system and and parts parts and and assembly. assembly. In production a prototype magnetic-wheel-type system, two vibration-type 3. Principle Locomotion s with same driving frequency and moving characteristics were produced. The E-shaped Asframe shownwas in made from 7, is vibrated by attractive acrylic a 1vibration-type mm-thick flat plate using a three-dimensional (3D)force processing rubber magnet. The vibration-type moves as a result vertical and horizontal machine. The dimensions E-shaped frame in this figure correspond to iron disks 40 mm components in diameter. forces generated by vibration component attached at an angle 60. When vibration-type with a rubber magnet is placed on a fixed iron disk, vibrating body 3. Principle Locomotion moves in direction in which vibration component is tilted. When a supported state is imposed to prevent motion vibration-type, As shown in 7, vibration-type is vibrated by attractive force rubber iron disk rotates as a result reaction force as a center on acrylic shaft. By magnet. The vibration-type moves as a result vertical and horizontal components inserting vibration-type into E-shaped acrylic frame in such a way that it is attracted forces generated by vibration component attached at an angle 60. When vibration-type to iron disk, as shown in 7, it is possible to rotate disk while preventing movement with a rubber magnet is placed on a fixed iron disk, vibrating body moves. In present system, vibration-type s A and B rotate in direction Actuators 2019, 8, x in which vibration component is tilted corresponding iron disks A and B, reby enabling system to move linearly over an iron structure Principle Principle locomotion. locomotion. When a supported state is imposed to prevent motion vibration-type, iron 4. Locomotive Characteristics Actuator System disk rotates as a result reaction force as a center on acrylic shaft. By inserting In this system,into a magnetic path isacrylic formed by disks and iron structure vibration-type E-shaped frame in two suchiron a way that it is attracted to beingdisk, inspected. Therefore, tothickness two iron disks and iron as shown in 7, iteffect is possible rotate and diskdiameter while preventing movement material four magnetic attached to center Adisk attractive force was. In present rings system, vibration-type s and on B rotate corresponding investigated, as shown in s and 9. 8 also givesover an overview experimental iron disks A and B, reby enabling8 system to move linearly an iron structure. apparatus. 4. Locomotive Characteristics Actuator System The attractive force between two iron disks and iron structure has a great influence on movement characteristics system. In this by system, magnetic is In this system, a magnetic path is formed two iron adisks and circuit iron constituted by two iron disks, four ring pieces, an thickness iron structure. For this reason, leakage structure being inspected. Therefore, effectand and diameter two iron disks magnetic flux permanent magnet is prevented reduced to a minimum, and an effective and material four magnetic rings attached to center disk on attractive attractive is generated. Magnetic for all four ring pieces. force wasforce investigated, as shown in materials s 8were and used 9. 8 also gives an overview experimental apparatus.

6 apparatus. The attractive force between two iron disks and iron structure has a great influence on The attractive force between two ironsystem. disks and iron structure hasaamagnetic great influence movement characteristics In this system, circuit on is movement characteristics system. In this system, a magnetic circuit is constituted by two iron disks, four ring pieces, and an iron structure. For this reason, leakage constituted by two iron disks, four ring pieces, and an iron structure. For this reason, leakage magnetic flux permanent magnet is prevented reduced to a minimum, and an effective magnetic flux generated. permanent magnet is prevented reduced to aring minimum, Actuators 2019, 8, 4 is 6 12 attractive force Magnetic materials were used for all four pieces. and an effective attractive force is generated. Magnetic materials were used for all four ring pieces. 8. Details magnetic-wheel-type system and experimental apparatus Details Details magnetic-wheel-type magnetic-wheel-type system systemand andexperimental experimentalapparatus. apparatus Experimental Experimental conditions conditions to to evaluate evaluate effect effect material material magnetic magnetic rings. rings. 9. Experimental conditions to evaluate effect material magnetic rings. The attractive force between two iron disks and iron structure has a great influence on movement characteristics system. In this system, a magnetic circuit is constituted by two iron disks, four ring pieces, and an iron structure. For this reason, leakage magnetic flux permanent magnet is prevented reduced to a minimum, and an effective attractive force is generated. Magnetic materials were used for all four ring pieces. 9 shows three conditions considered in evaluation effect material four magnetic rings. Type A has four permanent magnet rings same size, type B has three permanent magnets and one iron ring, and type C has two permanent magnets and two iron rings. The permanent magnet and iron rings have an outer diameter 11 mm, an inner diameter 7.8 mm, and a width 5 mm. Additionally, arrangement four rings in each type was as shown in 9. The permanent magnet ring is made NdFeB and is magnetized in axial direction. The surface magnetic flux density measured using a Tesla meter was 396 mt. The effect dimensions iron disks was also evaluated. Thicknesses 1, 1.5, and 2 mm, and diameters 40, 50, and 60 mm were considered in this evaluation. E-shaped acrylic frames were produced with dimensions corresponding to considered diameters iron disk. Prior to measurement attractive force, total mass magnetic-wheel-type system with two vibration-type s was measured. Table 1 gives total mass type A system with two vibration-type s for each combination considered diameters and thicknesses iron disks. As thickness iron disk increases, total mass system increases sharply.

7 Actuators 2019, 8, Table 1. Total mass type A magnetic-wheel-type system for different diameters and thicknesses iron disks. Diameter (mm) Total Mass (g) Thickness: 1 mm Thickness: 1.5 mm Thickness: 2 mm 40 mm mm mm The force attraction each type magnetic wheel to iron rail was measured using a spring balance. Table 2 gives attractive force each system type for iron disks with different thicknesses and a diameter 40 mm. For each type, attractive forces iron disks with thicknesses 1.5 and 2 mm were very similar. Considering tradef between total weight system and need for a relatively strong attractive force when moving over a structure, a disk thickness 1.5 mm was selected. Table 2. Attractive force magnetic-wheel-type systems with different disk thicknesses (disk diameter: 40 mm). Magnetic Ring Attractive Force (N) Thickness: 1 mm Thickness: 1.5 mm Thickness: 2 mm Type A Type B Type C For system with two vibration-type s shown in 1, Table 3 gives speed system in horizontal direction for different iron disk diameters when power input to electromagnet one vibration-type was set to 100 mw. The type A system with a disk diameter 40 mm achieved highest speed among considered cases. In this measurement, driving frequency system was 97 Hz. Table 3. Horizontal speed magnetic-wheel-type system types with different disk diameters. Diameter (mm) Speed (mm/s) Type A Type B Type C 40 mm mm mm In this study, magnetic wheel system with a disk 40 mm in diameter and 1.5 mm in thickness was adopted. 10 shows relationship between mass loaded on system and upward speed for type A with different iron disk thicknesses. In measurement, power input to electromagnet was set to 685 mw. Even under a load mass 120 g mounted on system, vertical upward movement at a speed 24 mm/s was possible on magnetic surface. 11 shows relationship between mass loaded on system and upward speed for each magnetic ring configuration. In this measurement, power input to electromagnet was set to 367 mw. The type A system showed excellent traction properties.

8 Actuators 2019, 8, x Upward speed plotted against load mass for different iron disk thicknesses. system and upward speed for type A with different iron disk thicknesses. In measurement, 11 shows power input relationship to electromagnet between was mass set loaded to 685 on mw. Even under system a load and mass 120 upward g mounted speed for on each magnetic system, ring configuration. vertical upward In this movement measurement, at a speed power 24 input mm/s to was Actuators 2019, 8, possible electromagnet on was magnetic set to 367 surface. mw. The type A system showed excellent traction properties. The effect tilt angle iron structure on system speed was n studied. 12 shows definition tilt angle β and two cases that were considered in investigating its effect on speed. The tilt angle was varied, and system speed was measured in case motion along front and slide-on-ceiling planes iron rail. 13 shows speed plotted against angles β1 and β2 iron rail with respect to horizontal plane under an input power 150 mw. In this figure, solid line and dashed lines represent variation in β1 and β2, respectively, as defined in 11. The tilt angles β1 and β2 were varied from 90 (straight downward) to 90 (straight upward). In this figure, β1 corresponds to movement along front plane, and β2 corresponds to movement along slide-on-ceiling plane. Since attractive force F support part changes as a result influence weight system, for β1 = β2 = 0, speeds two movement types are different. In addition, for β1 = β2 = 90, movement is equivalent to wall-climbing movement. 10. Upward speed plotted against load mass for for different iron iron disk disk thicknesses. 11 shows relationship between mass loaded on system and upward speed for each magnetic ring configuration. In this measurement, power input to electromagnet was set to 367 mw. The type A system showed excellent traction properties. The effect tilt angle iron structure on system speed was n studied. 12 shows definition tilt angle β and two cases that were considered in investigating its effect on speed. The tilt angle was varied, and system speed was measured in case motion along front and slide-on-ceiling planes iron rail. 13 shows speed plotted against angles β1 and β2 iron rail with respect to horizontal plane under an input power 150 mw. In this figure, solid line and dashed lines represent variation in β1 and β2, respectively, as defined in 11. The tilt angles β1 and β2 were varied from 90 (straight downward) to 90 (straight upward). In this figure, β1 corresponds to movement along front plane, and β2 corresponds to movement along Upward Upward speed speed plotted plotted against against load load mass mass for for different different magnetic magnetic ring ring configurations. configurations. slide-on-ceiling plane. Since attractive force F support part changes as a result influence The effect weight tilt angle ironsystem, structure for on β1 = β2 = 0, system speeds speed was two n movement studied. types are 12 shows different. definition In addition, for tilt β1 angle = β2 = β90, and movement two cases that is equivalent were considered to inwall-climbing investigating its movement. effect on speed. The tilt angle was varied, and system speed was measured in case Actuators motion 2019, 8, x along front and slide-on-ceiling planes iron rail Upward speed plotted against load mass for different magnetic ring configurations. 12. Experimental setup to measure effect tilt angle iron rail on speed 12. Experimental setup to measure effect tilt angle iron rail on speed magnetic-wheel-type system for motion in front and slide-on-ceiling planes. magnetic-wheel-type system for motion in front and slide-on-ceiling planes.

9 Actuators 2019, 8, shows speed plotted against angles β 1 and β 2 iron rail with respect to horizontal plane under an input power 150 mw. In this figure, solid line and dashed lines represent variation in β 1 and β 2, respectively, as defined in 11. The tilt angles β 1 and β 2 were varied from 90 (straight downward) to 90 (straight upward). In this figure, β 1 corresponds to movement along front plane, and β 2 corresponds to movement along slide-on-ceiling plane. Since attractive force F support part changes as a result influence weight system, 12. Experimental for β 1 = β 2 setup = 0, to measure speeds effect two movement tilt angle types iron are rail different. on speed In addition, for β 1 = βmagnetic-wheel-type 2 = 90, movement is equivalent system for to motion wall-climbing in front and movement. slide-on-ceiling planes. 13. Speed system in in two two considered planes planes motion motion plotted plotted against against tilt angle tilt angle β β iron iron rail. rail. 5. Turning Properties Actuator System 5. Turning Properties Actuator System In this system, movement is limited to one direction by its movement principle. Two SMA In this system, movement is limited to one direction by its movement principle. Two (TOKI Corporations, Trademark: BioMetal, , Heiwajima, Tokyo, Japan) coils and two SMA (TOKI Corporations, Trademark: BioMetal, , Heiwajima, Tokyo, Japan) coils friction pads were incorporated into magnetic-wheel-type system, and its ability to and two friction pads were incorporated into magnetic-wheel-type system, and its execute turning operations was examined. 14 shows an overview system capable ability to execute turning operations was examined. 14 shows an overview executing turning operations. An SMA coil spring and a friction pad were respectively attached to system capable executing turning operations. An SMA coil spring and a friction pad were rods A and B, forming E-shaped acrylic frame via a conductor. Table 4 gives properties respectively attached to rods A and B, forming E-shaped acrylic frame via a conductor. Table 4 SMA coil spring. The length SMA coil spring, with no current flowing through it, is 40 mm. gives properties SMA coil spring. The length SMA coil spring, with no current flowing through it, is 40 mm. Table 4. Properties shape memory alloy (SMA) coil spring. As shown in 15, when a direct current is applied to SMA coil spring by connection to a direct current (DC) power Outer supply, Diameter temperature Transformation SMA coil Resistance spring surpasses per Input transition Diameter Wire Point Meter Current temperature. The iron disk and friction pad are n put into contact with each or by SMA coil spring 0.62 mm 150 µm contracted SMA coil spring, forming a fulcrum where C 400 Ω 180 ma iron disk does not rotate. In this state, when vibration-type B is operated, a moment is applied at fulcrum, and system As shown can turn in in a clockwise 15, whendirection. a current Since two is applied SMA to coil springs SMA coil and spring two friction by connection pads are to aemployed direct current in this (DC) setup, power supply, system temperature can be turned clockwise SMA coilor spring counterclockwise, surpasses depending transition temperature. on which SMA The coil iron spring diskis and contracted. friction In this pad way, are n put into system contact can with move each in any or direction. by contracted SMA coil spring, forming a fulcrum where iron disk does not rotate. In this state, when vibration-type B is operated, a moment is applied at fulcrum, and system can turn in a clockwise direction. Since two SMA coil springs and two friction pads are employed in this setup, system can be turned clockwise or counterclockwise, depending on which SMA coil spring is contracted. In this way, system can move in any direction. In measurement, input power to electromagnet each vibration-type was set to 405 mw.

10 Table 4. Properties shape memory alloy (SMA) coil spring. Table 4. Properties shape memory alloy (SMA) coil spring. Outer Diameter Transformation Resistance per Outer Diameter Transformation Resistance per Input Current Diameter Wire Point Meter Input Current Diameter Wire Point Meter SMA coil8,spring 0.62 mm 150 μm C 400 Ω 180 ma Actuators 2019, 4 SMA coil spring 0.62 mm 150 μm C 400 Ω 180 ma 14. Magnetic-wheel-type system capable turning operation. Magnetic-wheel-type systemcapable capable Magnetic-wheel-type system turning turningoperation. operation. 15. Principle turning operation. 15. Principle turning operation. 15. Principle turning operation. Table 5 gives clockwise and counterclockwise turning speeds when horizontal and vertical planes are set as plane motion system. The results given in this table demonstrate that turning speeds in counterclockwise or clockwise directions are approximately equal. The rotation speed in vertical plane motion (wall surface) is lower than that horizontal plane motion. This is because weight system affects its movement in vertical plane.

11 Actuators 2019, 8, Table 5. Turning speed magnetic-wheel-type system in vertical and horizontal planes. Clockwise ( /s) Vertical Plane Counter Clockwise ( /s) Clockwise ( /s) Horizontal Plane Counter Clockwise ( /s) Conclusions An system combining two iron disks and two electromagnetic-vibration-type s was proposed and tested. The experimental results reveal that proposed system can pull 1.8 times its own weight when power input into electromagnet is 685 mw. In addition, a configuration capable turning operations combining SMA coil springs and friction pads was proposed. It was demonstrated that system is capable turning in any direction. The system can rotate at a rotation speed 11 /s, even if it is set on a vertical plane. The possibility using such a system to perform inspection large structures was demonstrated. Future work will involve exploration methods improving pulling characteristics and step movement system and investigation coupling multiple systems. Author Contributions: H.Y. initiated and supervised development and wrote paper, I.K. and S.S. performed development, design, assembly and integration prototype. Conflicts Interest: The authors declare no conflict interest. References 1. Shen, W.; Gu, J.; Shen, Y. Permanent Magnetic System Design for Wall-Climbing Robot. In Proceedings IEEE International Conference on Mechatronics & Automation, Beijing, China, 7 10 August Lee, G.; Park, J.; Kim, H.; Seo, T.W. Wall Climbing Robots with Track-wheel Mechanism. In Proceedings IEEE International Conference on Machine Learning and Computing, Guillin, China, July Fukuda, T.; Matsuura, H.; Arai, F.; Nishibori, K.; Sakauchi, H.; Yoshi, N. A Study on Wall Surface Mobile Robots. Trans. Jpn. Soc. Mech. Eng. 1992, 58, Kawasaki, S.; Kikuchi, K. Development a Small Legged Wall Climbing Robot with Passive Suction Cups. In Proceedings International Conference on Design Engineering and Science, Pilsen, Czech Republic, 31 August 3 September Yoshida, Y.; Ma, S. A Wall-Climbing Robot without any Active Suction Mechanisms. In Proceedings IEEE International Conference on Robotics and Biomimetics, Karon Beach, Thailand, 7 11 December Miyake, T.; Ishihara, H.; Yoshimura, M. Basic Studies on Wet Adhesion System for Wall Climbing Robot. In Proceedings IEEE/RSJ International Conference on Intelligent Robots and Systems, San Diego, CA, USA, 29 October 2 November Apostolescu, T.C.; Udrea, C.; Duminica, D.; Ionascu, G.; Bogatu, L.; Cartal, L.A. Development a Climbing Robot with Vacuum Attachment Cups. In Proceedings International Conference on Innovations, Recent Trends and Challenges in Mechatronics, Bucharest, Romania, September Akhtaruzzaman, M.; Samsuddin, N.; Umar, N.; Rahman, M. Design and Development a Wall Climbing Robot and its Control System. In Proceedings International Conference on Computer and Information Technology, Dhaka, Bangladesh, December Suzuki, M.; Hirose, S. Proposal Swarm Type Wall Climbing Robot System Anchor Climber and Development Adhering Mobile Units. Robot. Soc. Jpn. 2010, 28, [CrossRef] 10. Khirade, N.; Sanghi, R.; Tidke, D. Magnetic Wall Climbing Devices A Review. In Proceedings International Conference on Advances in Engineering & Technology, Singapore, March Kim, J.H.; Park, S.M.; Kim, J.H.; Lee, J.Y. Design and Experimental Implementation Easily Detachable Permanent Magnet Reluctance Wheel for Wall-Climbing Mobile Robot. J. Magn. 2010, 15, [CrossRef] 12. Yoon, K.H.; Park, Y.W. Controllability Magnetic Force in Magnetic Wheels. IEEE Trans. Magn. 2012, 48, [CrossRef]

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