Linear Motor Technology Research Articles

Design of a linear motor-based magnetic levitation train prototype

<span>This study explores the modelling of a magnetic levitation train and its implementation using a microcontroller. Magnetic levitation (maglev) is a technology that enables vehicles to levitate and move without wheels. Maglev research has been conducted globally, but maglev trains haven't received much attention. Due to the sophisticated linear motor technology for contactless transit, building a maglev train requires enormous investments. This paper is crucial for understanding the linear motor technologies necessary for levitation and propulsion. The primary objectives of this study include creating a model of the maglev train using a linear motor circuit, investigating the maglev effect concerning different coil and magnet types, and monitoring the train's propulsion and levitation using a microcontroller. This work constructs a linear motor system for the maglev train, comprising a mechanical structure with a permanent magnet for levitation and electromagnets for propulsion. A microcontroller is employed to sense the magnetic field, produced by the permanent magnet and electromagnets. In summary, this paper successfully designed a maglev train prototype using a linear motor circuit to establish the repulsive mechanism for both levitation and propulsion, with levitation~1 cm from the track and demonstrated the ability to move along a 30 cm track.</span>

A cost-effective linear propulsion system featuring PMEDW for HTS maglev vehicle: design, implementation, and dynamic test

Since 2021, the first high-speed, high-temperature superconducting maglev engineering prototype has proven its practical feasibility. However, the pressing need to mitigate the high costs of the current linear synchronous motor (LSM) technology remains paramount. This study aims to tackle this issue by introducing a novel, cost-effective propulsion way featuring the PMEDWs, optimizing its specifications, studying electromagnetic characteristics, fabricating a physical prototype, and conducting line tests to confirm application feasibility. Firstly, the conceptual prototype is introduced, outlining its functionality and principles. Subsequently, employing dynamic simulation models, structural specifications are optimized, and electromagnetic characteristics are evaluated. Afterwards, a comprehensive HTS maglev prototype weighting 1200 kg equipped with four PMEDWs and measurement system is designed and fabricated. Finally, validation of the simulation model effectiveness is conducted using a dedicated test rig. Dynamic line tests along a 165-meter line measure the performance metrics of the speed, levitation and propulsion gap, lateral and vertical accelerations, and propulsion and guidance forces, and maximum operation speed of 3. 03 m/s at n = 500 rpm. This study implements the physical prototype and dynamic testing of the PMEDW propulsion system, and confirms its feasibility for the first time, and the estimated cost is approximately one-tenth of the existing LSM motors in the 165-m test line. This technology promises significant innovation in linear propulsion methods, offering an economical alternative for Maglev vehicles.

Impacts of vehicle light-weighting on wheel wear and RCF and a novel ultralight vehicle design

Vehicle light-weighting is a critical design target for rail vehicles, as it reduces energy consumption and enhances the vehicle capacity and dynamic performance, making the railway system more attractive in addressing the rising environmental challenges and increasing demand in transportation. This paper presents a quantitative analysis of the impact of vehicle light-weighting on wheel wear and rolling contact fatigue (RCF), using the USFD wear law, the shakedown map and the Tγ approach. A conventional metro vehicle is utilized as a baseline model, and the mass reductions from different vehicle components (i.e., car-body, bogie frame and wheelset) are implemented for the simulation considering various running scenarios. The effect of mass reduction on wheel wear can be divided into two aspects: quasi-static wheel load and wheel-rail dynamic interaction. In short-radius curves, the change in static axle-load predominantly determines wheel wear, whereas in large-radius curves and tangent track, the wheel-rail dynamic interaction plays an important role, thus showing different rates of wear reduction when mass reduction is achieved respectively from car-body, bogie frames and wheelsets. Reducing vehicle mass can significantly reduce wheel damage of RCF on short-radius curves with curve radii above 400 m, while there is a risk of increasing RCF on tight curve R250, due to the impaired function of wear to counteract the crack propagation. This work also exhibits a specific innovative ultralight vehicle design, where the linear synchronous motor technology is applied to reduce substantially the mass of the vehicle without impairing the capability to provide the required amount of tractive effort. The proposed ultralight vehicle can reduce the wheel wear by approximately 40% and shows substantial benefit for preventing RCF damage, compared to a conventional vehicle.

<b>Development of Inverter-less Excitation Method for a Linear Rail Brake</b>

Studies have been carried out on rail brakes applying linear induction motor technology. This brake is capable of generating braking force without contact. In addition to the aspect of non-contact brakes, no onboard power supply for energizing this brake is required by using dynamic braking. This dynamic braking is performed with an excitation inverter, however there is a need to have a method which does not use an excitation inverter to reduce cost. Therefore, the authors devised an inverter-less excitation method using the self-excitation phenomenon of induction generators and tested it on a track-wheel testing machine. It was clarified that the method devised is useful as a low-cost excitation system.

Focus on microscopy, imaging, and nanotechnology

Focus on microscopy, imaging, and nanotechnology

Control design for a lower-limb paediatric therapy device using linear motor technology

Abstract Background Rehabilitation robots support delivery of intensive neuromuscular therapy and help patients to improve motor recovery. This paper describes the development and evaluation of control strategies for a novel lower-limb paediatric rehabilitation robot, based on linear-motor actuator technology and the leg-press exercise modality. Methods A functional model was designed and constructed and an overall control strategy was developed to facilitate volitional control of pedal position based on the cognitive task presented to the patient, together with automatic control of pedal forces using force feedback and impedance compensation. Results Each independent drive for the left and right legs can produce force up to 288 N at the user's foot. During dynamic testing, the user maintained a variable target position with root-mean-square tracking error (RMSE) of 3.8 ° with pure force control and 2.8 ° with combined force/impedance control, on a range of periodic motion of 20–80 °. With impedance compensation, accuracy of force tracking was also slightly better (RMSE of 9.3 vs. 9.8 N, force/impedance vs. force control only). Conclusions The control strategy facilitated accurate volitional control of pedal position and, simultaneously, accurate and robust control of pedal forces. Impedance compensation showed performance benefits. Control accuracy and force magnitude are deemed appropriate for rehabilitation of children with neurological impairments, but, due to current levels required, linear motor technology may not be suitable for applications where higher force is needed. Further work is required to validate the device within the target population of impaired children and to develop appropriate patient-interface software.

A shear‐wave seismic system using full‐waveform inversion to look ahead of a tunnel‐boring machine

ABSTRACTIn the near surface with unconsolidated soils, shear‐wave properties can often be characterised better and with a higher resolution than compressional‐wave properties. To enable imaging ahead of a tunnel‐boring machine, we developed a seismic prediction system with a few shear‐wave vibrators and horizontal receivers. The boring process is interrupted at regular intervals to carry out active surveys. The vibrators are then pushed against the rock or soil in front of the cutting wheel of the machine. The design of the vibrators is based on linear synchronous motor technology that can generate very low frequencies, starting at 5 Hz. These vibrators generate a force in a direction perpendicular to the tunnel axis. Horizontal receivers measure the particle velocity, mainly due to the horizontally polarised shear waves. Because imaging with conventional migration methods suffers from artefacts, caused by the incomplete aperture and inaccuracies in the assumed velocity model, we use two‐dimensional horizontally polarised shear full‐waveform inversion to resolve the subsurface shear properties. The classic cycle‐skipping problem, which can make the application of full‐waveform inversion cumbersome, is avoided by the capacity of the vibrators to generate low frequencies. In this paper, we demonstrate the capabilities of the proposed seismic system through a number of synthetic and field experiments.

A Fault Diagnosis Method for Oil Well Pump Using Radial Basis Function Neural Network Combined with Modified Genetic Algorithm

This paper presents a new method to diagnose oil well pump faults using a modified radial basis function neural network. With the development of submersible linear motor technology, rodless pumping units have been widely used in oil exploration. However, the ground indicator diagram method cannot be used to diagnose the working conditions of rodless pumping units because it is based on the load change of the polished rod suspension point and its displacement. To solve this problem, this paper presents a new method that is applicable to rodless oil pumps. The advantage of this new method is its use of a simple feature extraction method and advanced genetic algorithm to optimize the threshold and weight of the RBF neural network. In this paper, we extract the characteristic value from the operation parameters of the submersible linear motor and oil wellhead as the input vector of the fault diagnosis model. Through experimental analysis, the proposed method is proven to have good convergence performance, high accuracy, and high reliability.

Application of linear motors in mechatronic devices

Nowadays linear motion can be achieved in many different ways, traditional and new. Based on this, it is of great importance to know the advantages and disadvantages of different technologies in use. In this paper, traditional pneumatic and mechanical linear actuators are compared with the new linear motor technologies, which are used in mechatronic devices. Differences between various linear actuator types are studied, and a discussion is presented regarding their characteristics.

Development of a Rail Brake Derived from Linear Motor Technology

Studies have been carried out on a rail brake developed by applying a linear induction motor technology, called LIM-type rail brake. This brake is capable of generating braking forces without contact. In addition, this method decreases the rise in rail temperature, and on-board supply of electric power is not required by using dynamic braking. It is however necessary to install this brake in the limited space between front and rear wheels of the bogie. A prototype rail brake system was designed and built and its electromagnetic characteristics were examined on a test track in RTRI. These investigations revealed that the LIM-type rail brake could be applicable for practical use.

Dynamic cellular actuator arrays and the expanded fingerprint method for dynamic modeling

A key step to understanding and producing natural motion is creating a physical, well understood actuator with a dynamic model resembling biological muscle. This actuator can then serve as the basis for building viable, full-strength, and safe muscles for disabled patients, rehabilitation, human force amplification, telerobotics, and humanoid robotic systems. This paper presents a cell-based flexible actuator modeling methodology and the General Fingerprint Method for systematically and efficiently calculating the actuators’ respective dynamic equations of motion. The cellular actuator arrays combine many flexible ‘cells’ in complex and varied topologies for combined large-scale motion. The cells can have varied internal dynamic models and common actuators such as piezoelectric, SMA, linear motor, and pneumatic technologies can fit the model by adding a flexible element in series with the actuator. The topology of the cellular actuator array lends it many of its properties allowing the final muscle to be catered to particular applications. The General Fingerprint Method allows for fast recalculation for different and/or changing structures and internal dynamics, and provides an intuitive base for future controls work. This paper also presents two physical SMA based cellular actuator arrays which validate the presented theory and give a basis for future development.

Performance of Linear Motor Type Rail Brake Using Roller Rig Test Bench

Studies have been carried out on a rail brake applying linear induction motor technology, called LIM-type rail brake. This brake is capable of generating braking forces without contact. In addition, this method decreases the rise in rail temperature, and no onboard supply is required by using dynamic braking. It is necessary however to install this brake between front and rear wheels of the bogie. A prototype rail brake system was designed and built and its electromagnetic characteristics were examined on a test bench with a roller rig. These investigations revealed that the LIM-type rail brake could be applicable for practical use.

Excitation Method of Linear-Motor-Type Rail Brake without Using Power Sources by Dynamic Braking with Zero Electrical Output

The eddy current rail brake is a type of braking system used in railway vehicles. Because of problems such as rail heating and problems associated with ensuring that power is supplied when the feeder malfunctions, this braking system has not been used for practical applications in Japan. Therefore, we proposed the use of linear induction motor (LIM) technology in eddy current rail brake systems. The LIM rail brake driven by dynamic braking can reduce rail heating and generate the energy required for self-excitation. In this paper, we present an excitation system and control method for the LIM rail brake driven by “dynamic braking with zero electrical output”. The proposed system is based on the concept that the LIM rail brake can be energized without using excitation power sources such as a feeder circuit and that high reliability can be realized by providing an independent excitation system. We have studied this system and conducted verification tests using a prototype LIM rail brake on a roller rig. The results show that the system performance is adequate for commercializing the proposed system, in which the LIM rail brake is driven without using any excitation power source.

Design Considerations and Experimental Verification of a Rail Brake Armature Based on Linear Induction Motor Technology

This paper describes the design considerations and experimental verification of an LIM rail brake armature. In order to generate power and maximize the braking force density despite the limited area between the armature and the rail and the limited space available for installation, we studied a design method that is suitable for designing an LIM rail brake armature; we considered adoption of a ring winding structure. To examine the validity of the proposed design method, we developed a prototype ring winding armature for the rail brakes and examined its electromagnetic characteristics in a dynamic test system with roller rigs. By repeating various tests, we confirmed that unnecessary magnetic field components, which were expected to be present under high speed running condition or when a ring winding armature was used, were not present. Further, the necessary magnetic field component and braking force attained the desired values. These studies have helped us to develop a basic design method that is suitable for designing the LIM rail brake armatures.

General Atomics Linear Motor Applications: Moving Towards Deployment

This paper discusses a number of unique potential applications of linear synchronous and linear induction motors that have resulted from General Atomics' work on the Navy EMALS project for electromagnetically launching planes, and the Urban Maglev project, which uses a long-stator permanent magnet linear synchronous motor. The paper provides an overview of the linear motor technologies being used in these projects, including some of the technical challenges. Potential applications include the use of maglev technology to move cargo in and out of the ports, all-electric trucks which use the energy provided by the linear motor to charge onboard power, and retrofitting linear motors on existing rails to relieve pollution involved in moving cargo in urban settings.

Development and Analysis of a High Thrust Force Direct-Drive Linear Actuator

This paper presents the design and analysis of a novel high thrust force linear actuator with high backdrivability. This motor consists of a mover and a stator with spiral (helical) structure. The mover moves spirally in the stator, and the linear motion is extracted to drive the load. This motor is a direct-drive system and highly backdrivable. In this paper, a basic model and thrust-force/torque equations are proposed, and finite-element method analysis and experimental results of a prototype are presented. From experiments, the designed spiral motor achieves 2000-N rated thrust force. The thrust-force capabilities of the spiral motor are compared with other linear motors. It is confirmed that the spiral motor is almost close to the latest state of the art in linear motor technology.

Basic Characteristics of Rail Brake Systems Using Linear Motor Technology

An eddy-current rail brake system is effective in stabilizing the braking ability of trains because its braking force does not depend on adhesion between the wheel and the rail. However, the use of the existing type equipped with DC electromagnets causes the rail temperature to increase, bringing the possibility of rail bending. Because of this, it is impractical for use in Japan. Accordingly, we applied an AC electromagnet (the same as those used in linear induction motors) to the rail brake system to reduce rail temperature rise, and investigated its basic characteristics using a rotary-type test machine.

Relation between electrocardiographic repolarization changes and left ventricular filling pressure evaluated by Doppler echocardiography in patients with hypertensive heart disease

Rehabilitation robots support delivery of intensive neuromuscular therapy and help patients to improve motor recovery. This paper describes the development and evaluation of control strategies for a novel lower-limb paediatric rehabilitation robot, based on linear-motor actuator technology and the leg-press exercise modality.A functional model was designed and constructed and an overall control strategy was developed to facilitate volitional control of pedal position based on the cognitive task presented to the patient, together with automatic control of pedal forces using force feedback and impedance compensation.Each independent drive for the left and right legs can produce force up to 288 N at the user's foot. During dynamic testing, the user maintained a variable target position with root-mean-square tracking error (RMSE) of 3.8 ° with pure force control and 2.8 ° with combined force/impedance control, on a range of periodic motion of 20–80 °. With impedance compensation, accuracy of force tracking was also slightly better (RMSE of 9.3 vs. 9.8 N, force/impedance vs. force control only).The control strategy facilitated accurate volitional control of pedal position and, simultaneously, accurate and robust control of pedal forces. Impedance compensation showed performance benefits. Control accuracy and force magnitude are deemed appropriate for rehabilitation of children with neurological impairments, but, due to current levels required, linear motor technology may not be suitable for applications where higher force is needed. Further work is required to validate the device within the target population of impaired children and to develop appropriate patient-interface software.

Assessing Feasibility of Transport Megaprojects

Results of the Swissmetro European Market Study are presented. Swissmetro is a proposed high-speed passenger ground transportation system that would operate magnetically levitated trains in underground tunnels with reduced air pressure by using linear motor technology. The market study considered the market feasibility of constructing Swissmetro on potential European corridors. It evaluated technology, market conditions, European policy, investment costs, and risks associated with the project. The study conclusion was that there is not sufficient market potential for the Swissmetro system in European long-distance transport. The main problems with Swissmetro identified in the study were the long time necessary to bring the technology to commercial deployment; the lack of obvious corridors (most high-demand corridors will be served by high-speed rail by 2020); strong competition from other modes, such as air and high-speed rail; European Union policy of supporting an interoperable system of rail lines; Swissmetro's high capital and operating costs—plus the risk that these costs may be significantly underestimated—and Swissmetro's long construction time.

Electron projection lithography tool development status

In the development of an electron beam projection lithography (EPL) tool, the most important tasks are to develop the high-speed vacuum stage system, reliable vacuum body system, and total control system. Nikon has a long history of over 22 years in precision stage development for its optical lithography tools as well as over 10 years in electron beam (EB) instrument development such as the EB 60 with NTT. Recently, optical lithography stages have been developed based on air bearing and linear motor technologies. It is desirable and of minimum risk to utilize those technologies for the EPL system in order to shorten the total time period of development, but the requirements for the EB stage, body, and system control are much different from their optical counterparts and much more difficult. In this article development and implementation of the EPL vacuum stage system, vacuum body system, vacuum loader system, and control system are discussed and overviewed.