Magnetic Levitation Control Research Articles

Research on Magnetic Levitation Control Method under Elastic Track Conditions Based on Backstepping Method

The vehicle–guideway coupled self-excited vibration of maglev systems is a common control instability problem in maglev traffic while the train is suspended above flexible girders, and it seriously affects the suspension stability of maglev vehicles. In order to solve this problem, a nonlinear dynamic model of a single-point maglev system with elastic track is established in this paper, and a new and more stable adaptive backstepping control method combined with magnetic flux feedback is designed. In order to verify the control effect of the designed control method, a maglev vehicle–guideway coupled experimental platform with elastic track is built, and experimental verifications under rigid and elastic conditions are carried out. The results show that, compared with the state feedback controller based on the feedback linearization controller, the adaptive backstepping control law proposed in this paper can achieve stable suspension under extremely low track stiffness, and that it shows good stability and anti-interference abilities under elastic conditions. This work has an important meaning regarding its potential to benefit the advancement of commercial maglev lines, which may significantly enhance the stability of the maglev system and reduce the cost of guideway construction.

A Review of Levitation Control Methods for Low- and Medium-Speed Maglev Systems

Maglev transportation is a highly promising form of transportation for the future, primarily due to its friction-free operation, exceptional comfort, and low risk of derailment. Unlike conventional transportation systems, maglev trains operate with no mechanical contact with the track. Maglev trains achieve levitation and guidance using electromagnetic forces controlled by a magnetic levitation control system. Therefore, the magnetic levitation control system is of utmost importance in maintaining the stable operation performance of a maglev train. However, due to the open-loop instability and strong nonlinearity of the control system, designing an active controller with self-adaptive ability poses a substantial challenge. Moreover, various uncertainties exist, including parameter variations and unknown external disturbances, under different operating conditions. Although several review papers on maglev levitation systems and control methods have been published over the last decade, there has been no comprehensive exploration of their modeling and related control technologies. Meanwhile, many review papers have become outdated and no longer reflect the current state-of-the-art research in the field. Therefore, this article aims to summarize the models and control technologies for maglev levitation systems following the preferred reporting items for systematic reviews and meta-analysis (PRISMA) criteria. The control technologies mainly include linear control methods, nonlinear control methods, and artificial intelligence methods. In addition, the article will discuss maglev control in other scenarios, such as vehicle–guideway vibration control and redundancy and fault-tolerant design. First, the widely used maglev levitation system modeling methods are reviewed, including the modeling assumptions. Second, the principle of the control methods and their control performance in maglev levitation systems are presented. Third, the maglev control methods in other scenarios are discussed. Finally, the key issues pertaining to the future direction of maglev levitation control are discussed.

Disturbance rejection tube model predictive levitation control of maglev trains

Magnetic levitation control technology plays a significant role in maglev trains. Designing a controller for the levitation system is challenging due to the strong nonlinearity, open-loop instability, and the need for fast response and security. In this paper, we propose a Disturbance-Observe-based Tube Model Predictive Levitation Control (DO-TMPLC) scheme combined with a feedback linearization strategy for the levitation system. The proposed strategy incorporates state constraints and control input constraints, i.e., the air gap, the vertical velocity, and the current applied to the coil. A feedback linearization strategy is used to cancel the nonlinearity of the tracking error system. Then, a disturbance observer is implemented to actively compensate for disturbances while a TMPLC controller is employed to alleviate the remaining disturbances. Furthermore, we analyze the recursive feasibility and input-to-state stability of the closed-loop system. The simulation results indicate the efficacy of the proposed control strategy.

Magnetic Levitation Control of Doubly-Fed Linear Motor with Multi-Phase AC Excited Mover

Magnetic Levitation Control of Doubly-Fed Linear Motor with Multi-Phase AC Excited Mover

Mathematical modeling of robust automatic control system of magnetic levitation with uncertain parameters

The topic of the research is the development of automated control systems for real processes, which must satisfy various requirements, for example, resistance to unmodeled dynamics (robust stability), as well as meet the required quality of transient processes that arise in the case of external disturbances of various natures. In this regard, there is a need to create appropriate mathematical models for the control of non-stationary objects, the model of which includes uncertain parameters. The problem of developing and studying a mathematical model for controlling the process of electrodynamic magnetic levitation, the main problem of which is dynamic stability, is considered. It is noted that systems using the effect of magnetic levitation are widely used, for example, in shipbuilding, in elements of ship mechanisms, instrument making, as well as in the transportation of various cargoes. The relevance of the work related to the need to develop such automatic control systems that can suppress the emerging oscillatory motion of levitating bodies is substantiated. The initial mathematical model of the magnetic levitation control process, which has uncertain coefficients in differential equations and is nonlinear, is considered. To “hang” at a given (working) point of a levitating body, it is enough to create a mathematical control model in the vicinity of this point based on the linearization of the original mathematical model. A PID-based controller and feedback are added to the resulting model. The four controller coefficients are adjusted using special algorithms, taking into account the requirements for the robustness of the control system. Numerical experiments are carried out to analyze the behavior of the control system depending on the magnitude of the parameter uncertainty. Based on the analysis performed, a conclusion about the robustness of the developed control system for the object under consideration is made. The results of the study are presented in graphical form. The MATLAB system is used as a toolkit.

Motion Control of Capsule Robot Based on Adaptive Magnetic Levitation Using Electromagnetic Coil

In view of the magnetically actuated capsule robot applications in diagnoses of human stomach disease, the challenges that are associated with degrees-of-freedom (DOF), environmental adaptability, and the size of the entire system must be addressed. In this study, a new electromagnetic coil system that is based on adaptive magnetic levitation is presented; it is mainly composed of an independent orientation control electromagnetic coil and a magnetic levitation control electromagnetic coil. The system is designed to perform motion control of the capsule, including 3-DOF levitating translational motion control, and pitch and yaw motion control in levitation. In this manner, it compensates for the lack of previous magnetic levitation systems that were based on electromagnetic coils for the control of the tilt angle of the capsule. With torque-based actuation control, the tilt angle of the capsule can be controlled continuously with an angle increment of no more than 2 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\circ}$</tex-math> </inline-formula> (within 30 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\circ}$</tex-math> </inline-formula> ) during levitation. The capsule under the magnetic levitation control, which is based on the fuzzy proportional-integral -derivative controller, can maintain the stability of levitation; the error between the actual capsule position and the required position did not exceed 0.1 mm when the capsule was out of water or completely immersed in it. Moreover, the experiment of the capsule levitating from air to water further verifies the adaptability of the system with regard to the environment; this provides a new examination method for capsule endoscopy. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Note to Practitioners</i> —This work is caused by the motion manipulation problem of a magnetically driven capsule robot. Most of the existing magnetically driven capsule robots use a rolling or sliding method that fits tightly against the stomach wall, and these forms of motion make it possible to risk missing diagnoses in the examination of gastric diseases, and the maneuverability limits its further application. This paper proposes an adaptive control strategy for a magnetically driven capsule robot based on magnetic levitation motion. It allows the magnetically driven capsule robot to levitate to any position in the stomach for photography and observation without external mechanical support, and this levitation motion is sufficiently stable. In addition, the proposed capsule robot has independent orientation and position control, which has the potential to achieve automated inspection.

Development of a Conveyor Cart with Magnetic Levitation Mechanism Based on Multi Control Strategies

This paper presents the experimental magnetic levitation control development of Sanki Engineering airport luggage conveyor carts which have four magnetic levitation units working synchronously. With the PID controller, the state feedback controller and the zero-power controller refined by PID controller were implemented in the one magnetic levitation unit system and four-unit magnetic levitation system, and the displacement and the current were verified in a real-time system. The magnetic levitation unit had a fast response, and the control algorithms were easily implemented. The change of current and displacement were compared. In the one-unit system, the PID and state feedback controller react to the disturbance at the same speed and have similar power consumptions. For a disturbance on the zero-power controller, the system generates a transient current to deal with the load disturbance and finally settles to 0 A. The PID control for four magnetic levitation units of the conveyor cart has a better stable performance during synchronous operation. Under the control of state feedback controller, they can keep the cart statically stable with some oscillation. These characteristics are experimentally confirmed.

Magnetic Levitation Belt Conveyor Control System Based on Multi-Sensor Fusion

Belt conveyors are critical in coal transportation systems; however, they are supported by rollers, which incur high energy costs. Magnetic levitation support is adopted. The measurement of a magnetic levitation air gap is important, and a displacement sensor is usually used in real-time. To address the problems of poor linearity and low measurement stability of single displacement sensors in magnetic levitation systems, a magnetic levitation support system based on multi-sensor data fusion is proposed. First, an industrial camera sensor is used to collect images, and the suspended air gap is obtained through image processing. Second, using an extended Kalman filter, the photoelectric position sensor and industrial camera sensor are fused to the suspension air gap value in the process of suspension. The electromagnet current is controlled by the PID (proportion integration differentiation) control algorithm, and experiments are carried out. Experimental results showed that, compared with an estimation of the suspension state of two sensors before and after EKF fusion, the root mean square error is reduced by 0.0597 and 0.0081, respectively, compared with the measurement value of a single sensor. Moreover, the fusion data were more robust, thereby meeting the requirements of magnetic levitation control.

A Study on the Control Method of 6-DOF Magnetic Levitation System Using Non-Contact Position Sensors

Recently, due to the development of semiconductor technology, high-performance memory and digital convergence technology that integrates and implements various functions into one semiconductor chip has been regarded as the next-generation core technology. In the semiconductor manufacturing process, various motors are being applied for automated processes and high product reliability. However, dust and shaft loss due to mechanical friction of a general motor system composed of motor-bearing are problematic for semiconductor wafer processing. In addition, in the edge bread remove (EBR) process after the photoresist application process, a nozzle position control system for removing unnecessary portions of the wafer edge is absolutely necessary. Therefore, in this paper, in order to solve the problems occurring in the semiconductor process, a six-degrees-of-freedom (6-DOF) magnetic levitation system without shaft and bearing was designed for application to the semiconductor process system; and an integrated driving control algorithm for 6-DOF control (levitation, rotation, tilt (Roll-Pitch), X-Y axis movement) using the force of each current component derived through current vector control was proposed. Finally, the 6-DOF magnetic levitation system with the non-contact position sensors was fabricated and the validity of the 6-DOF magnetic levitation control method proposed in this paper was verified through a performance test using a prototype.

DEID-Based Control of Networked Rapid Control Prototyping System: Design and Applications

This article presents a novel networked rapid control prototyping (NRCP) system, which can significantly facilitate the theoretical analysis and product design of networked control systems (NCSs). The NRCP system consists of a PC controller equipped with MATLAB/Simulink software and an embedded target designed with open-source hardware, e.g., Raspberry Pi and STM32. Therefore, it benefits from the following advantages, such as simple structure, low cost, convenient deployment, and robust scalability. In order to verify the effectiveness and superiority of the proposed NRCP, a networked magnetic levitation control system (NMLCS) is developed on the basis of this NRCP system. Furthermore, a discrete-time equivalent-input-disturbance (DEID)-based model predictive control approach is proposed for NMLCS to deal with the common practical issues in NCSs, such as time delay and disturbance. Specifically, the time delay is modeled as delay-induced disturbance (DID), whose influence is effectively estimated and eliminated by the designed controller. Several experimental case studies are performed to verify the effectiveness of the NRCP, the DEID-based control algorithm, and the analytical method of DID.

Research on Gravity Compensation System of Planetary Rover Based on Electrodynamic Suspension

In this paper, an electrodynamic levitation gravity compensation system based on a new type of annular Halbach array permanent magnet is proposed. The magnetic levitation force model is established using the equivalent expansion method, and the reliability of the model is verified by comparing the results of numerical calculation and simulation analysis. Through magnetic field simulation experiments, the effects of rotating speed and air gap on magnetic levitation force and eddy current loss are analyzed. The control model of the electric magnetic levitation system considering the vertical speed is investigated, and the hybrid control method of force and position is used to realize the stable magnetic levitation control. Finally, an experimental platform is built to verify the feasibility of the electric magnetic levitation system. The results show that the magnetic levitation force can be improved and the eddy current loss can be reduced by setting the rotating speed and air gap reasonably.

Control of Time Delay in Magnetic Levitation Systems

The high-performance control of magnetic levitation (maglev) vehicles has encountered challenges in the form of time delays. In this letter, we model a reliable control method based on a Takagi-Sugeno fuzzy model aimed at solving the problem of air gap control of a magnetic levitation system for a maglev vehicle under time-delay conditions. The key idea is based on the global fuzzy model derived through sector nonlinearity to design a global controller utilizing the parallel distributed compensation method and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${H_\infty }$</tex-math></inline-formula> method. As a result, the stability of the system is guaranteed under conditions of mass parameter uncertainty, disturbance, and time delay. The theoretical analysis, numerical simulations, and experimental results consistently show the effectiveness of the control method.

Multisource Oscillation Suppression Control of Magnetic Levitation High Speed Permanent Magnet Motor

The multi-source oscillation of magnetic levitation permanent magnet motor (ML-PMM) under high speed operation is inevitable. The reasons are the influence of the strong coupling characteristics of high speed permanent magnet motor(HSPMM), the nonlinear characteristics of power converter and the coupling characteristics of magnetic levitation control system. Aiming at the multi-source oscillation caused by magnetic levitation system and HSPMM, the multi-source oscillation suppression control method suitable for magnetic levitation-high speed permanent magnet motor(ML-HSPMM) is studied in this paper. The stability of ML-HSPMM and the small signal model of the motor are analyzed. Finally, the control strategy of is verified by simulation and experiment.

Design and characteristics of a new aerostatic bearing stylus sensor for surface measurement

Stylus profilometry is extensively employed in practice due to its wide measurement range and praiseworthy stability. However, its lever structure will cause nonlinear errors and mitigated precision. Given this context, this paper proposes a new aerostatic bearing stylus sensor (ABSS) for surface measurement, which inherits the stability and large-scale measuring range while avoiding the structural nonlinear errors of the conventional stylus profilometry. The designed ABSS is composed of a magnetic levitation control system and an aerostatic bearing device in the vertical and horizontal directions, respectively. Furthermore, the bearing capacity and the radial dynamic characteristics are analyzed to ensure stylus’ scanning stability and rapid response. Template experiments with different scanning velocities of the stylus are performed to verify the natural frequency and obtain the critical velocity. Finally, the surface two/three-dimensional topographies reconstruction validates the repeatability and accuracy of the proposed ABSS compared to a commercial conventional stylus profilometry.

Vertical direction conveyance control of the magnetic levitation control system using the electromagnet with the embedded displacement sensor

Vertical direction conveyance control of the magnetic levitation control system using the electromagnet with the embedded displacement sensor

Simulation and Test of Energy Consumption of High-Tc Superconducting Coils in Electromagnetic Levitation System

In order to evaluate the energy consumption of the superconducting magnetic levitation system with real-time control, the methods of simulation and test were used to study the AC plus DC loss of the superconducting coil. The simulation established a 2D finite element model in COMSOL, which was based on the H equations method with simple form and fast calculation speed. The test was carried out on a new type of measurement system, which adopted the electrical method with high sensitivity, simple operation and easy implementation. The results of simulation and test showed that, under normal working conditions, the levitation current in the form of AC plus DC produced a relatively small energy loss below $1mW$ per meter. This conclusion is helpful for the promotion and application of superconducting magnetic levitation control system.

Fuzzy Sliding Mode Control of Magnetic Levitation System of Controllable Excitation Linear Synchronous Motor

In order to improve the ability of magnetic levitation feed platform of controllable excitation linear synchronous motor (CELSM) to resist external disturbance, a sliding mode control method based on fuzzy switching gain adjustment is proposed. According to the operation mechanism of CELSM, the voltage equation, flux equation, magnetic levitation force equation, and state equation of CELSM are established. The sliding mode surface is designed, and the integral term is introduced to eliminate the steady-state error of the system. The reaching law is designed to reduce chattering by using the saturation function instead of the sign function. Fuzzy logic reasoning is used to estimate the switching gain, to cancel the unknown disturbance, and further weaken the chattering of the system. The sliding mode controller based on fuzzy switching gain adjustment is designed, and the system is simulated in MATLAB environment. The simulation results show that the fuzzy sliding mode control algorithm can improve the dynamic performance of the system and weaken chattering. The feasibility of this algorithm is proved. The experimental platform of CELSM magnetic levitation system is built to carry out partial experimental research on the magnetic levitation control system.

Comparison of Ziegler-Nichols and Cohen Coon tuning method for magnetic levitation control system

Magnetic levitation is an example of a nonlinear system that is naturally unstable. In the control system field, it can be also used to check the effectiveness of control methods. Unlike other researches overcoming by analytical method, this research investigates the solution of the nonlinearity of the magnetic field by placing two effect hall sensors on the top and bottom of magnetic coils. After decreasing the effect of nonlinearity, two PID control tuning methods, Ziegler Nichols (ZN) and Cohen Coon (CC), are compared to obtain an appropriate control structure and its initial parameters. The experimental result shows that the best control structure of ZN method is PID whereas its initial parameters, Kp, Ti, and Td, are 15.33, 0.036 and 0.009, respectively. The rise-time and settling time of the response are 0.54s and 0.59s. The appropriate control structure is PI control whereas Kp and Ti are 30.05 and 0.012 from CC method. The rise-time and settling time resulted are 0.8s and 0.67s. The ZN method with PID control structure has a better response with smaller rise-time and settling time than PI control from CC Method. This research is benefit for solving a problem dealing with magnetic levitation control.

Magnetic Levitation Control and Bending of Flexible Steel Plate

Magnetic Levitation Control and Bending of Flexible Steel Plate

Magnetic Levitation Control Based on Flux Density and Current Measurement

This paper presents an active magnetic levitation application that exploits the measurement of coil current and flux density to determine the displacement of the mover. To this end, the nonlinear behavior of the plant and the physical sensing principle are modeled with a finite element approach at different air gap lengths and coil currents. A linear dynamic model is then obtained at the operating point as well as a linear relation for the displacement estimates. The effectiveness of the modeling approach and the performance of the sensing and control techniques are validated experimentally on an active magnetic levitation system. The results demonstrate that the solution is able to estimate the displacement of the mover with a relative error below 3% with respect to the nominal air gap. Additionally, this approach can be exploited for academic purposes and may serve as a reference to implement simple but accurate active magnetic levitation control using low-cost, off-the-shelf sensors.