Guideway System Research Articles

Integrating reinforcement learning and supervisory control theory for optimal directed control of discrete-event systems

Directed control is crucial for implementing controllers on programmable logic controllers. A directed controller is one that actively selects at most one controllable event (control command) to execute at any instant. This study investigates the numerical optimization problem of directed control for discrete-event systems, such as traffic systems and robotic systems. By integrating supervisory control theory and reinforcement learning, an algorithmic procedure is designed to synthesize an optimal directed controller, which minimizes the total cost associated with event execution while ensuring the safety and liveness of the controlled system. Two improved Q-learning algorithms incorporating dynamic parameter adaptation strategies are developed to enhance the global search ability of basic Q-learning. To demonstrate applicability and effectiveness, we apply the proposed method to control a guideway system and a multi-train traffic system, respectively. The experimental results indicate the superiority of the proposed method over the comparison methods.

Dynamic model of high-speed maglev train-guideway bridge system with a nonlinear suspension controller

To improve the anti-interference ability of maglev trains, a dynamic model of the high-speed maglev train with a nonlinear suspension controller for the guideway system is proposed in this paper. Based on the nonlinear characteristics of the magnetic suspension system, a nonlinear decoupling controller is designed using the feedback linearization theory. Then, a high-speed maglev train model is refined with a guideway coupling system, consisting of a maglev train simulated as a multi-body dynamics model with 537 degrees of freedom and a spatial finite element model of the guideway. Taking the Shanghai high-speed maglev train as an example, the correctness of the computational model is verified by comparing the modeling results with field measurement data, and the control effectiveness of the nonlinear controllers and the traditional PD controllers is compared considering different train speeds and disturbance forces. The results show that the suspension gap under the decoupling control is smaller than that under the PD control during the train operations. Under the same disturbance force, the decoupling control exhibits better control performance than the PD control. The variation amplitudes of the magnetic pole gaps are generally linearly related to the disturbance force.

Electromagnetic Guideway System for Continuous Steel Plates: Fundamental Consideration of Vibration Characteristics From Damping Factor of Steel Plate

Electromagnetic Guideway System for Continuous Steel Plates: Fundamental Consideration of Vibration Characteristics From Damping Factor of Steel Plate

Magnetic Guideway System for Continuous Steel Plates Using Attractive Force of Electromagnets

Magnetic Guideway System for Continuous Steel Plates Using Attractive Force of Electromagnets

Thermal Characteristics of a Vertical Hydrostatic Guideway System for Precision Milling Machine Applications

This paper investigates the thermal characteristics of a vertical guideway system for precision milling machine applications by considering three heat sources, namely motor heat, viscous shearing heat of hydrostatic bearings, and friction heat from a ballscrew nut. A finite element (FE) model using ANSYS/Fluent was used to simulate the thermal characteristics of the system by considering the oil film friction of the hydrostatic bearings in the operational feed speed and heat generation in the ballscrew nut. Eight K-type thermocouples were installed in the vertical hydrostatic guideway system to measure the temperature rise in the key components. Nine thermal experiments of the vertical hydrostatic guideway system under three operational feed rates, namely 1.25, 2.5 and 5 m/min were conducted to measure the temperature of seven thermocouples in practical running conditions. The experimental temperature data then was used to adjust the FE model setting to guarantee the accurate prediction of the thermal deformation in real operational conditions. The FE model of the vertical hydrostatic guideway system built in this study can be used to predict the thermal deformation of worktable at center point at any running conditions. At a sliding feed rate of 1 m/s, the thermal positioning error of worktable at center point was 0.1539 µm in the X direction, 0.0009 µm in the Y direction and 2.0246 µm in Z direction.

Investigation on the influence of structural rigidity on the stiffness of aerostatic guideway considering fluid-structure interaction

The static performances of the aerostatic guideway are significantly influenced by the fluid-structure interaction (FSI) effect. This paper investigates the FSI process between the air film and two-stage cantilever structure of the slider based on a two-way transient FSI model, in which the thickness and shape of actual air film can be acquired. Moreover, the stiffness of the aerostatic guideway system with two different materials 38CrMoAl nitriding steel and 7075 aluminum alloy, is investigated numerically and compared experimentally. It proves that the structural rigidity of the slider has a non-negligible impact on the stiffness of the aerostatic guideway system. The inner mechanism of this phenomenon is further discussed to provide meaningful guidance for the design of the aerostatic guideway system.

Effect of long-wave deviation of stator plane on high-speed maglev train and guideway system

Pre-stressed concrete hybrid guideways are often used in the high-speed maglev transit system. The long-wave deviations of the stator plane based on the initial pre-camber could be possibly caused by temperature and concrete creep. When the high-speed maglev train moves over the guideways system, significant vehicular vibration could be triggered by the long-wave deviations. In the present study, the influence of the long-wave deviations on the dynamic characteristics of high-speed maglev train is investigated. First, the vertical analysis model of the coupled maglev train-guideway system is presented, and the loading model of long wave deviations of the stator plane is determined. Then, the effect of several key parameters, that is, initial pre-camber, the long wave deviations levels, train speeds, and the bridge span, on the dynamic response of maglev train-guideway system is evaluated. The results show that the initial pre-camber will improve the driving safety index and riding comfort level, especially for the middle vehicle of the high-speed maglev train. The results also indicate that the existence of long-wave deviation on the stator plane could deteriorate the driving safety and comfort level of the vehicle. Meanwhile, higher train speed and long-wave deviations levels as well as larger bridge span result in larger vehicle dynamic response.

Trajectory determination of a specific point on a moving guideway using a laser-based measurement method with application in automatic workpiece assembly

The trajectory of guideway influences spatial position and pose of a moving workpiece. Laser beam and visual image are used for joint measurement to continuously track a specified point on moving guideway. Meanwhile, the geodetic datum is established in the reference plane formed by structured light, which is emitted by an electronic leveling device. Further, the trajectory of a specified point on moving guideway in the world coordinate system is determined, providing effective geometric information for assembly. This paper takes a two-axis guideway system in an instrument for testing precision reducer as an example. The trajectory is obtained by the proposed method. Based on measurement results, it provides a practical application. Assembly experiments prove that the proposed method is useful. The guideway is in a universal application and this feasible method can be applied to other similar industrial fields.

Dynamic positioning error analysis and modeling of CNC machine tool guideway system

The dynamic characteristics of the XY worktable are thoroughly analyzed in this study to accurately compensate the measurement errors of on-machine measurement systems caused by the dynamic and static characteristics under multiple factors. The dynamic positioning error model of the XY worktable motion components is established, and the theoretical model of the dynamic positioning error of the XY worktable is derived. The actual parameters of the experimental platform for the correlation error of CNC machine tools are substituted into the model for theoretical calculation and analysis. Results show that the motion speed of the worktable, the weight of the measured workpiece, the installation position of the workpiece, and the friction force are the main factors causing the dynamic positioning error. Dynamic positioning error analysis and verification experiments were conducted to verify the validity of the proposed theoretical model. Experimental results show that a regular change occurs between the dynamic positioning error and the movement speed of the XY worktable, and the actual measurement results are basically consistent with the theoretical calculation results. The research results can lay a good foundation for establishing the measurement error prediction and compensation model of on-machine measurement systems of CNC machine tools and improving its measurement accuracy.

Improvement on Curve Negotiation Performance of Suspended Monorail Vehicle Considering Flexible Guideway

This work presents the investigation and improvement on curve negotiation performance of suspended monorail vehicle considering a flexible guideway. First, a spatial train–guideway interaction model of suspended monorail system (SMS) is established based on the secondary development of ANSYS software. Then, the dynamic analysis of the train over the flexible curved guideway is conducted, and the curve negotiation performance of the vehicle and the guideway vibration feature are revealed. Subsequently, several crucial design parameters that significantly influence the curve negotiation performance of the vehicle are found, and their influences on the train–guideway dynamic responses are systematically investigated. Finally, by comprehensively considering the dynamic indexes of the vehicle–guideway system, the optimal ranges of these crucial design parameters are obtained. Results show that decreasing the radial stiffness of guiding tyre can effectively reduce the lateral vibration levels of vehicle and guideway, but it would increase the lateral displacements of the bogie and hanging beam; and the radial stiffness is finally suggested to be around 1[Formula: see text]kN/mm by comprehensively considering all dynamic indexes. Increasing the initial compression displacement of guiding tyre can well limit the lateral displacements of the bogie and the hanging beam, thus enhancing the train running safety; however, it would intensify the vehicle-guideway lateral vibration level; especially, the optimal initial compression displacement of guiding tyre is related to its radial stiffness characteristics. To ensure a good curve negotiation performance of vehicle and guideway vibration level, the stiffness of the anti-roll torsion bar and the initial gradient angle of the installed trapezoid four-link suspended device are suggested to be 1.0[Formula: see text]MNm/rad and 65–[Formula: see text], respectively.

Evaluation of Dynamic Characteristics of a Hybrid Guideway System

This paper presents the dynamic characteristics of a hybrid guideway system that employs sliding guides as the primary support and rolling guides to decrease the friction force and improve servo response. A drive table with a linear motor was fabricated, and the dynamic responses of the proposed hybrid guideway to command input and disturbances were measured. The results indicate that the developed guideway system provides high dynamic stiffness without sacrificing the accuracy of servo response. Furthermore the floating action of the table influenced the dynamic compliance of the guide in the horizontal direction.

A magnetorheological hydrostatic guideway system for machining vibration control

A novel magnetorheological (MR) hydrostatic guideway system for control of machining vibration is proposed. After the analysis of the relationship between correlation parameters and working variables, a computational fluid dynamics (CFD) model is presented. With this model incorporated into the commercial code FLUENT, a numerical study on performance parameters of MR hydrostatic guideway system is carried out efficiently. Static stiffness and damping coefficients are calculated by using dynamic mesh technique based on perturbation theory. Analysis on dynamic behaviors of the MR hydrostatic guideway under the action of machining force is performed. An experimental study has been undertaken in order to validate the accuracy of the numerical model. It is observed that working variables (magnetic flux density, initial pressure ratio and load ratio) have significant effects on the performance characteristics (flow rate, frictional force, stiffness and damping) of the system. Optimal static stiffness and high damping can be expected simultaneously. Dynamic stiffness of the system can be improved and vibration caused by machining force can be reduced remarkably by increasing magnetic flux density. It is effective to control machining vibration by applying MR hydrostatic guideway system.

Influence of liquid film thickness on bearing characteristics of magnetic‐liquid suspension guide‐way

The magnetic-liquid suspension guide-way (MLSG) adopts the double support form of permanent magnetic suspension and hydrostatic pressure. It can greatly enhance the bearing capacity and rigidity of the guide-way system. The liquid film thickness is the main influencing factor on both the bearing capacity of the hydrostatic system and the permanent magnetic force. This paper analysed the effect of liquid film thickness on the static, dynamic and vibration index of MLSG. Firstly, this paper introduced the structural characteristics and supporting mechanism of MLSG. Secondly, based on flow equation, the static pressure equation, the permanent magnetic force equation and the force balance equation, the transfer function of single DOF supporting system of MLSG in constant flow supply mode is presented, and analysed the influence of the thickness of liquid film on single DOF supporting performance of MLSG. The results show that with the increase of the thickness of the liquid film, the bearing capacity of guide-way, the static stiffness, the dynamic stiffness and the natural frequency decrease, and the adjust time, the total power loss, the amplitude amplification coefficient increases, the phase margin is almost unchanged. The study can provide a theoretical basis for the design of MLGS in engineering practice.

Preview Control of Hydrostatic Guideway for Ultraprecision CNC Machine Tools

An active preview control strategy is presented to suppress the vibration of hydrostatic guideway under dynamic machining force. A state space model of closed hydrostatic guideway system is built, and the predictability of machining force during cutting process is analyzed. Numerical simulation model of preview compensation control systems is established. The displacements of slide carriage are compared under the condition of no control, optimal control and active preview control. The variations of oil recess pressure are observed when using the two latter control methods. The results show that maximum displacement of slide carriage by using active preview control method reduces 73.3% compared to the optimal control method, and reduces 94.1% compared to the method without any control. Besides, the compliance of the oil recess pressure to machining force is improved by 23%. Finally, an experiment evaluating the displacement of slide carriage and variation of oil recess pressure is carried out and the numerical predictions agree with the experimental results. It is effective to control machining vibration of hydrostatic guideway by using active preview control strategy.

Influence of parameters of PM controller on vibration performance of liquid hydrostatic guide-way system

The vibration of liquid hydrostatic guide-way system during the working process makes a full impact on the machining precision of the numerically-controlled machine tool. The hydrostatic guide-way under the regulation of PM (Progressive Mengen) controller is taken as the research object. First, based on the force balance equation of hydrostatic guide-way, two kinds of vibration model of hydrostatic guide-way are established, respectively, and oil film stiffness equation and damping coefficient formula are derived. Second, the inherent frequency and amplitude of the guide-way system are derived. Third, the influence of PM controller parameters on the inherent frequency and amplitude of the guide-way system is analysed theoretically. The result indicates that the inherent frequency of the guide-way system changes with PM controller parameter and it makes a full impact on the active vibration amplitude of the hydrostatic guide-way system, but not the passive vibration amplitude. This article is provided a reference for the practical application of PM controller.

Improvement of the damping capacity of the linear damper with an oil groove in the linear guideway system

This article presents an experimental investigation into the damping characteristics of a linear damper with a newly designed oil groove. The damping performance of the damper is tested in four different viscosity grades by the sweep frequency method. And a test bench is used to move the damper for a several kilometers to examine the damping maintenance. The experimental results show that a higher oil viscosity leads to a higher damping capacity of the linear damper, and the increase in the oil viscosity will improve the damping maintenance of the damper. The newly designed oil groove efficiently improved the damping capacity of the linear damper; a proper oil selection will further optimize the effect of the oil groove via minimizing the oil leakage.

Experimental Analysis of the Gas Film Damping Effect in an Aerostatic Guideway under Microscale

ABSTRACTThis article studies the mechanism of gas film damping on the aerostatic guideway system at a microscale with the modified Reynolds equation. The slide film damping force due to the fluid viscous effect is calculated, and the squeeze damping force caused by the gas compression and escape between two plates is analyzed. The damping ratio in the calculation model for the slide film damping is compared with the calculated results from the experiment and the finite element analysis results. Using the results of the study, the optimal supply pressure is designed. The method applied in this article provides the theoretical basis for the analysis and solution of the dynamic performance of an aerostatic guideway.

Dynamic Analysis of High-Speed MAGLEV Vehicle–Guideway System: An Approach in Block Diagram Environment

A magnetically levitated (MAGLEV) train is the future of rapid ground transport. They are much faster, energy efficient; require very less maintenance and pollution free. The present study outlines an approach for the modelling and simulation of MAGLEV vehicle–guideway in a block diagram environment and thereafter optimizes the suspension parameters for increased ride comfort. This has been accomplished with the help of SIMULINK which provides a graphical editor, customizable block libraries and solvers. The guideway has been modelled as a two-span continuous beam. The guideway surface roughness was defined by power spectral density function. The influence of vehicle speed and surface roughness on the vehicle–guideway response has been studied. Use of optimized suspension parameters indicated 60 % reduction in car-body vertical acceleration, whereas the guideway maximum deflection showed a fall of 25 %.

Motion straightness of hydrostatic guideways considering the ratio of pad center spacing to guide rail profile error wavelength

Due to the error averaging effect of pressured oil film in hydrostatic guideways, motion straightness of the slider is smaller than the profile error of guide rails. In spite of this, structural parameters of the guideway system have dramatic effects on the error averaging coefficient. Therefore, it is necessary to investigate the relationship between the structural parameters of the guideway system and slider motion straightness. In this paper, effect of the ratio (m λ ) of pad center spacing to guide rail profile error wavelength on motion straightness was the primary focus. A static analysis model based on the error averaging effect considering pad center spacing in open hydrostatic guideways with four pads was established. Linear displacement motion error of the slider with different system structural parameters was solved, and slider motion straightness was calculated using least-square method. A grinding machine LGF1000 was used in experiments, and the slider vertical motion straightness was improved to 0.98 μm/600 mm from 2.08 μm/600 mm after using the lapping process on a specific guide rail along the Y-axis for change the m λ . In addition, precision was improved by 52.9 %. Results show that m λ has significant influence on vertical motion straightness of the slider. Increasing the pad center spacing m allows a reduction in motion straightness for m λ equal or lesser than 0.5. However, a decrease in the pad center spacing is useful to decrease the motion straightness, when m λ is equal or larger than 0.72.

Review of Project Connect

Project Connect — a planning consortium sponsored by the City of Austin, Capital Metro, the Capital Area Metropolitan Planning Organization, and Lone Star Rail — proposes to build a 9.5-mile, high-capacity transit line in Austin from East Riverside & Grove to Austin Community College’s Highland campus. Transit vehicles would follow a dedicated guideway — either rails or an exclusive busway — with trains or buses stopping about every one-half mile. Although buses are being considered as an alternative, it is clear that Project Connect planners already favor rail; as a presentation by Project Connect concludes: “Urban Rail is the appropriate mode to meet system needs.”There are several problems with this proposal. First, the proposed rail line is not truly high-capacity transit; though Project Connect has failed to admit it, buses can actually move more people than light rail. Second, the line is projected to cost $1.38 billion, but planners have failed to demonstrate the need for an expensive, dedicated guideway system of either bus or rail. In fact, the peak-hour demand projected for the line is well below the capacity of either buses or light rail. Finally, project planners have greatly overestimated the benefits of the proposed line. For example, far from relieving congestion, light rail will make it worse as it will have priority at traffic signals, disrupting the flow of traffic for everyone else. For much less than the cost of a single fixed-guideway transit line serving a few travelers, Austin can both improve bus service and relieve traffic congestion for all travelers. Traffic signal coordination, staggered bus stops in high-demand areas, increased bus frequencies, double-decker buses on high-demand routes, and the construction of more HOT lanes will smooth traffic flows and provide better transportation for everyone in the Austin area.