Magnetic Wheel Research Articles

Suitable Method for Improving Friction Performance of Magnetic Wheels with Metal Yokes

A magnetic-wheeled robot is a type of robot that inspects large steel structures instead of humans, and it can run on a three-dimensional path by using wheels with built-in permanent magnets. For the robots to work safely, their magnetic wheels require both magnetic attractive forces and friction forces. Planetary-geared magnetic wheels, which we have developed, make direct contact with their yokes on the running surface to ensure their magnetic attractive force. However, this design decreases their frictional performance more than common magnetic wheels covered with soft materials. Therefore, the yokes require methods that can improve their frictional performance without decreasing their attractive force. To consider the best method for the use of magnetic wheels, this study has run experiments with five types of yokes, which have different processing. As a result, the yokes with corroded surfaces could have maintained the attractive force more than 90% of the time and increased their traction forces by about 36% in static conditions and about 30% in dynamic conditions compared to yokes with no machining. The main reasons for these experimental results are that the rust layer has stable irregularities on the surface and includes ferromagnetic materials.

FalconScan: A hybrid UAV-crawler system for NDT inspection of elevated pipes in industrial plants

Periodic non-destructive testing (NDT) of pipes and tanks is vital in industrial plants, such as Oil & Gas facilities, to proactively detect defects and corrosion before leaks and forced shutdowns occur. This paper presents a hybrid system, consisting of a UAV and a crawler, which enables detailed contact-based inspection of elevated pipes, in pursuit of eliminating the need for dangerous scaffolding and manual inspection to improve safety and reduce cost. Similar to avian animals, the UAV autonomously perches on the pipe to conserve energy. A small inspection crawling robot is carried by the UAV, and is subsequently released onto the pipe’s surface to inspect its health. The crawler uses magnetic wheels for agile mobility and houses an ultrasonic testing (UT) sensor to thoroughly scan the pipe and detect wall thinning, which is a precursor for leaks. Finally, the crawler re-docks with the UAV, which in turn detaches from the pipe to fly back home or inspect another pipe. The multi-robot system is designed for and tested on pipe diameters as small as 8 in.

Necessary Conditions for Running through a Flange by Using Planetary-Geared Magnetic Wheels

To discuss and consider the necessary conditions for magnetic-wheeled robots with planetary-geared magnetic wheels, this paper provides comparing static calculations about three orientations in running a flange with real experiments. SCPREM-I, a magnetic-wheeled robot, was developed for running through a flange from the bottom to the top. This robot has four magnetic wheels with a built-in planetary gearset. In experiments, however, the robot sometimes fails to run through a flange in three orientations. In this study, we statically analyze SCPREM-I to find the conditions necessary for running through the flange. We calculate the forces around the front and rear wheels in the three orientations. As a result, it has been found that the chassis of the SCPREM-I applies a forward force to the wheels when it runs through the flange. In addition, it has been found that the normal force of the A-Legs is balancing with the driving force of the wheels when the SCPREM-I fails to run through the flange.

Study of Magnetic Wheels with Planetary Gears which Make Running on Flange Paths Easy for Magnetic Wheeled Robot

Study of Magnetic Wheels with Planetary Gears which Make Running on Flange Paths Easy for Magnetic Wheeled Robot

Modeling of attractive force of magnetic wheel under different wall structure and attitude used for climbing robot

Modeling of attractive force of magnetic wheel under different wall structure and attitude used for climbing robot

Spinning a Liquid Wheel and Driving Surface Thermomagnetic Convection with Light.

A typical Tesla thermomagnetic engine employs a solid magnetic wheel to convert thermal energy into mechanical energy, while thermomagnetic convection in ferrofluid is still challenging to observe because it is a volume convection that occurs in an enclosed space. Using a water-based ferrofluid, a liquid Tesla thermomagnetic engine is demonstrated and reports the observation of thermomagnetic convection on a free surface. Both types of fluid motions are driven by light and observed by simply placing ferrofluid on a cylindrical magnet. The surface thermomagnetic convection on the free surface is made possible by eliminating the Marangoni effect, while the spinning of the liquid wheel is achieved through the solid-like behavior of the ferrofluid under a strong magnetic field. Increasing the magnetic field reveals a transition from simple thermomagnetic convection to a combination of the central spin of the spiky wheel surrounded by thermomagnetic convection in the outer region of the ferrofluid. The coupling between multiple ferrofluid wheels through a fluid bridge is further demonstrated. These demonstrations not only unveil the unique properties of ferrofluid but also provide a new platform for studying complex fluid dynamics and thermomagnetic convection, opening up exciting opportunities for light-controlled fluid actuation and soft robotics.

Agile robotic inspection of steel structures: A bicycle‐like approach with multisensor integration

AbstractThis paper introduces an innovative and streamlined design of a robot, resembling a bicycle, created to effectively inspect a wide range of ferromagnetic structures, even those with intricate shapes. The key highlight of this robot lies in its mechanical simplicity coupled with remarkable agility. The locomotion strategy hinges on the arrangement of two magnetic wheels in a configuration akin to a bicycle, augmented by two independent steering actuators. This configuration grants the robot the exceptional ability to move in multiple directions. Moreover, the robot employs a reciprocating mechanism that allows it to alter its shape, thereby surmounting obstacles effortlessly. An inherent trait of the robot is its innate adaptability to uneven and intricate surfaces on steel structures, facilitated by a dynamic joint. To underscore its practicality, the robot's application is demonstrated through the utilization of an ultrasonic sensor for gauging steel thickness, coupled with a pragmatic deployment mechanism. By integrating a defect detection model based on deep learning, the robot showcases its proficiency in automatically identifying and pinpointing areas of rust on steel surfaces. The paper undertakes a thorough analysis, encompassing robot kinematics, adhesive force, potential sliding and turn‐over scenarios, and motor power requirements. These analyses collectively validate the stability and robustness of the proposed design. Notably, the theoretical calculations established in this study serve as a valuable blueprint for developing future robots tailored for climbing steel structures. To enhance its inspection capabilities, the robot is equipped with a camera that employs deep learning algorithms to detect rust visually. The paper substantiates its claims with empirical evidence, sharing results from extensive experiments and real‐world deployments on diverse steel bridges, situated in both Nevada and Georgia. These tests comprehensively affirm the robot's proficiency in adhering to surfaces, navigating challenging terrains, and executing thorough inspections. A comprehensive visual representation of the robot's trials and field deployments is presented in videos accessible at the following links: https://youtu.be/Qdh1oz_oxiQ and https://youtu.be/vFFq79O49dM.

NuBot: A Magnetic Adhesion Robot with Passive Suspension to Inspect the Steel Lining

The steel lining of huge facilities is a significant structure, which experiences extreme environments and needs to be inspected periodically after manufacture. However, due to the complexity (crisscross welds, curved surface, etc.) of their inside environments, high demands for stable adhesion and curvature adaptability are put forward. This paper presents a novel wheeled magnetic adhesion robot with passive suspension applied in nuclear power containment called NuBot, and mainly focuses on the following aspects: (1) proposing the wheeled locomotion suspension to adapt the robot to the uneven surface; (2) implementing the parameter optimization of NuBot. A comprehensive optimization model is established, and global optimal dimensions are properly chosen from performance atlases; (3) determining the normalization factor and actual dimensional parameters by constraints of the steel lining environment; (4) structure design of the overall robot and the magnetic wheels are completed. Experiments show that the robot can achieve precise locomotion on both strong and weak magnetic walls with various inclination angles, and can stably cross the 5 mm weld seam. Besides, its maximum payload capacity reaches 3.6 kg. Results show that the NuBot designed by the proposed systematic method has good comprehensive capabilities of surface-adaptability, adhesion stability, and payload. Besides, the robot can be applied in more ferromagnetic environments and the design method offers guidance for similar wheeled robots with passive suspension.

Autonomous Ultrasonic Thickness Measurement of Steel Bridge Members Using a Climbing Bicycle Robot

This paper presents the development of a steel-climbing bicycle robot integrated with an ultrasonic sensing device towards autonomous thickness measurement of steel bridge members. The bicycle-like robot has two magnetic wheels controlled by two independent steering actuators, which navigates on various steel surfaces (flat, curved, rough, concave, and convex). The compact ultrasonic sensing device is capable of high-voltage pulse excitation, filtering/amplification of the received ultrasonic signal, and high-speed analog-to-digital conversions (up to 80 MHz). Along with the ultrasonic sensing device, the robot carries a dual element transducer, an automatic gel couplant dispenser, a position tracking sensor, and a camera. A mounting/retrieving mechanism of the transducer is designed to ensure the reliable contact of the transducer on steel surfaces. The camera view assists an operator to safely navigate the robot to measurement locations, properly dispense gel couplant, and firmly press the transducer on a measurement surface. The automated robot localization provides accurate thickness measurement locations, which are mapped real-time in three-dimensional (3D) space together with the robot’s travel path. We validate the performance of the developed system in several indoor and outdoor tests. Weblink to a supplementary video demonstrating the robot’s maneuverability and ultrasonic thickness measurements is available in the Data Availability Statement of this article.

벽 등반 드론 자세에 따른 모듈형 영구자석 휠-레그의 부착력

Improving battery performance is crucial for increasing drone flight time. However, developing individual parts can also enhance mission performance and extend operating time. By attaching a drone to a wall instead of hovering in the air, the operating time and range of task performance can be extended. This study focuses on the adhesion force of a modular permanent magnet wheel leg for wall climbing drones. The wheel leg comprised several spokes without a rim. It could climb obstacles higher than wheel radius and provide a large adhesion area. An equation for the adhesion force of the wheel leg was derived, considering mechanical factors such as drone size, inclination of the ferromagnetic wall, and drone posture. A simple experimental model was created to verify the validity of the adhesive force equation. The effectiveness of the derived equation was confirmed by experimentally measuring the angle of the ferromagnetic wall that losT adhesion according to mechanical factors and comparing it with the derived adhesion force.

English

Many innovative approaches have been proposed in modelling and designing the wall climbing robot. Among all these approaches, the main focus is the adhesive mechanism of a wall climbing robot (WCR). This adhesive mechanism is a critical design consideration feature when discussing system reliability. There are various types of adhesive mechanisms like magnetic, suction cup, vacuum, rope and rail, electrostatic, fusion or hybrid type etc., of which the fusion or hybrid mechanism is found to have more payload to weight ratio (P/W value). This paper proposes a hybrid method using both permanent magnet (Nd FeB magnetic wheel) and solenoid electromagnet suction at the central disc. The design is validated using a free-body diagram, and its magnetic adhesion is analyzed by visualizing the magnetic flux density lines through Finite Element Method Magnetics (FEMM) analysis software. Three different analyses in FEMM are made, and their corresponding outcome is discussed concerning its graph.

Scanning X-Ray Detector For Nondestructive Testing

For the nondestructive testing of long objects at the Paton Electric Welding Institute (Ukraine), an X-ray detector was created that uses a digital medical mini sensor. To increase the testing area, adjacent digital X-ray images are stored and stitched together by software into a combined image. The thickness of the objects that can be tested with this type of sensor, which has a maximal voltage of 70 kV, is 6 mm for aluminum. This imaging process can be used in a wide variety of applications. In a second approach, we developed a mobile detector with a remote control for radiographic testing (RT) of objects in limited and hard-to-reach spaces. One application utilizes a robotic car with independently controlled magnetic wheels that allows the detector to move in any direction over the entire surface of the object under test.

Optimization Design and Parameter Analysis of a Wheel with Array Magnets

At present, a large number of magnetic wall-climbing robots are applied to various magnetically conductive metal facades for detection and anti-corrosion work. Limited by the wall-climbing mechanism and adsorption device, most wall-climbing robots can only climb on smooth walls, and it is difficult to adapt to complex walls. Therefore, by studying the multi-media magnetic circuit conduction mechanism, a permanent magnetic adsorption wheel with a magnet array arrangement was designed in this study and applied to a hinge-type wall-climbing robot. By analyzing the influence of structural parameters on the adsorption performance and optimization design, a magnetic wheel structure with a symmetric structure that can meet a variety of adsorption requirements was obtained. To analyze the mechanical characteristics of the wall-climbing robot under complex facade conditions, we researched the adsorption performance of the designed magnetic wheel in different wall structures. Finally, the adhesion force of the magnetic wheel was verified through experimental measurements, and it was found that the hinged wall-climbing robot could adapt to different structural features and complete wall-transition and obstacle-crossing movements.

Research on the Mechanism of Curve Passing for Bogie on a Medium-Low Speed Maglev With Mid-Set Air Spring

AbstractIn the research of rail vehicles, mechanism of curve passing is one of the hot spots, which essentially elucidates the conditions of vehicle curve passing and points out the direction for improving vehicle curve passing ability. As one of the new members of rail transportation, the curve passing capability of medium-low speed maglev directly affects its application and promotion in the field of rail transportation. In order to reveal the mechanism of curve passing for medium-low speed maglev, this paper first studies the necessary conditions for the conventional wheelset curve passing based on the mechanism of curve passing for the conventional wheelset. Second, on the basis of comparing the structure and motion relationship of the conventional wheelset, the independent wheelset and the magnetic wheelset (bogie of medium-low speed maglev), the theoretical derivation of the magnetic wheelset curve passing conditions are carried out to obtain its theoretical solution based on the curve passing conditions of the conventional wheelset. Finally, the conditions of curve passing for the magnetic wheelset are verified by dynamic simulation, and the mechanism of curve passing for the medium-low speed maglev bogie is revealed. Through the research, it can be found that: (1) The mechanism of curve passing for the magnetic wheelset is different from that of the traditional wheelset and the independent wheelset. The speed variance and regulating torque are the composite functions of running speed, curve radius, track gauge, superelevation, guiding stiffness and yaw angle of the magnetic wheelset. (2) When the magnetic wheelset passes through the curve, its motion posture switches between “” and “,” while the unilateral magnetic wheel shows a motion which is similar to “hunting.” (3) Ignoring the factors such as structure and irregularity, it can conduct that the curve capacity of the magnetic wheelset could be improved by increasing the curve radius, reducing the speed, curve superelevation and gauge to a certain extent. This study theoretically reveals the mechanism of curve passing for the medium-low speed maglev bogie, which provides a certain reference for the subsequent design of the medium-low speed maglev and the improvement of the medium-low speed maglev curve capacity.

Spatial Trajectory Tracking of Wall-Climbing Robot on Cylindrical Tank Surface Using Backstepping Sliding-Mode Control

Wall-climbing robots have been well-developed for storage tank inspection. This work presents a backstepping sliding-mode control (BSMC) strategy for the spatial trajectory tracking control of a wall-climbing robot, which is specially designed to inspect inside and outside of cylindrical storage tanks. The inspection robot is designed with four magnetic wheels, which are driven by two DC motors. In order to achieve an accurate spatial position of the robot, a multisensor-data-fusion positioning method is developed. The new control method is proposed with kinematics based on a cylindrical coordinate system as the robot is moving on a cylindrical surface. The main purpose is to promote a smooth and stable tracking performance during inspection tasks, under the consideration of the robot's kinematic constraints and the magnetic restrictions of the adhesion system. The simulation results indicate that the proposed sliding mode controller can quickly correct the errors and global asymptotic stability is achieved. The prototype experimental results further validate the advancement of the proposed method; the wall-climbing robot can track both longitudinal and horizontal spatial trajectories stably with high precision.

Optimization Design and Trajectory Error Compensation of a Facade-Adaptive Wall-Climbing Robot

In recent years, many wall-climbing robots have been developed in the field of petrochemical storage tank maintenance. However, it is difficult for most of them to be widely used due to common problems such as poor adsorption capacity, poor adaptation to elevation, and low trajectory tracking accuracy. In order to solve the problem of the robot not being able to achieve high-precision operation on curved surfaces, a new wall-climbing robot system is designed. Based on the magnetic wheel adsorption method, a passive adaptive motion mechanism that can adapt to walls with different curvatures is proposed. In order to improve the trajectory tracking accuracy of the wall-climbing robot, the kinematic model of the wall-climbing robot is simplified, a velocity compensation controller is designed, and the stability of the controller is proved by introducing the Lyapunov equation. Through experiments, the controller designed in this paper is compared with the conventional controller to verify the effectiveness and superiority of the controller. The experimental results show that the robot can move safely and stably on curved surfaces, with improved tracking accuracy and reduced trajectory deviation caused by response time lag, and meets the maintenance operation requirements of wall-climbing robots.

Numerical and Experimental Investigations of Flaws Detection in Multilayer HTS Tapes by Magnetothermal Technique

This paper presents a numerical and experimental studies on the non-destructive testing of high temperature superconducting (HTS) multilayer tapes at room temperature, by eddy current thermography (ECT). An experimental setup is developed in which a rotating magnet wheel inductor is used instead of electromagnetic inductors to avoid the inherent thermal disturbance. A 3-D magnetothermal modelling approach is developed for the verification of the experimental results and the simulation of situations that cannot be reproduced experimentally, in particular the verification of the detection limits as a function of the shape and location of the defects. Simulation and experimental results are in good agreement.

Development of an articulated mobile robot moving on magnetic curved walls and passing over obstacles

We developed an articulated mobile robot that can move on the magnetic curved walls and traverse through obstacles for wall surface inspections of a large tank. This robot is equipped with magnetic wheels and is able to stick to and move on steel wall. We add passive roll joints and turn off the torque of the pitch joints to ensure the wheels keep in contact with the curved surface. The developed robot is tested through experiments in the laboratory and also in a field test at the World Robot Summit 2020. The experiments are conducted to confirm the movements of the robot on the curved wall surface and when the units are lifted for obstacle traversal. As the results, the robot is not able to overcome an obstacle near the wall such as a handrail but is able to move freely on the curved wall surface and traverse some obstacles on the corner.

Nondestructive Testing of Multilayer HTS Tapes by Using Eddy Current Thermography

This article presents numerical and experimental investigations of the structural control of multilayer high temperature superconducting (HTS) tapes, using eddy current thermography at room temperature. A rotating magnet wheel is used as inductor to avoid the thermal disturbance of current supplied inductors. A 3-D magnetothermal modeling approach based on an integro-differential formulation in terms of the electric vector potential is developed for eddy current computation in the HTS tapes; associated to a thermal modeling using the finite difference method. The source magnetic field is calculated using the magnetic surface charge model. The simulation results are confirmed by the measurements, both highlighting the potential of such control to detect structural defects, such as delamination.

Design and analysis of a wheel-leg compound variable curvature ship hull cleaning robot

Underwater robotic cleaning devices are promising in ship hull maintenance for biofouling removal, but there are still some challenges for commercial application. Due to the complex surface of the ship hull, larger adsorptive force is needed for climbing robots to solve the problem of poor fitting between rigid structure and ship hull, which calls for more driving power. To mitigate the gap, this paper proposed a flexible wheel-leg composite moving mechanism for ship hull cleaning robots. The designed adjustable wheel leg, which is composed of three leg frames on the rotating shaft, eliminates the magnetic wheel's position constraints and expands the movement space. The relation equations of flip angle, pitching angle, turning angle, and hull curvature radius are generated and analyzed based on the robot's posture and steering motion. The mechanical properties of anti-slippage and anti-shedding under different motion states were studied so that the robot's critical point and limit adsorption force could be determined and verified. Simulation results show that the robot has good motion stability.