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A precision stopping measurement device to automatically detect position errors of an urban train at railway stations
Abstract
Precision stopping of an urban train at a railway station with platform screen doors is essential to passenger safety and timely revenue service. This paper presents a precision stopping measurement device to automatically detect the position error of an urban train at a railway station with platform screen doors; the device is used primarily for initial calibration during test runs before revenue service begins. The precision stopping measurement device that has been developed is composed of a platform module to detect the stopping error of the train using laser light, a vertical pattern to reflect the laser light, and an on-board module to record the stopping error automatically via wireless communication. The usefulness of the precision stopping measurement device presented here has been demonstrated using field tests with an actual Maglev train in Korea.
... Chen, Wang and Li [12], Ha, Kim and Kang [13] have developed a precise stopping method for Korean metro system while considering the Platform Screen Door (PSD) in stations. They used a transmitter which is a laser light to provide the system with stop error at stations and an onboard receiver which wirelessly communicates with the platform modules. ...
... The condition of rail in terms of being wet, oily or dry will affect the friction between rails and train wheels which will be captured in our model for TASC simulation by using (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13) and (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14). Where: ...
... The condition of rail in terms of being wet, oily or dry will affect the friction between rails and train wheels which will be captured in our model for TASC simulation by using (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13) and (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14). Where: ...
In a conventional train signalling system, stopping a train at stations is the responsibility of train drivers. Before each station, a signal known as Home Signal in railway terminology, warns the driver that the train is approaching a station. However, due to different brake system characteristics and capabilities, different track profiles as well as different competency levels of drivers, it is a challenging task to stop a train precisely by just one braking action while maintaining a uniform quality of ride.
In addition to this, the use of platform screen doors (PSD) in railway stations can introduce various challenges for planners, track engineers, rolling stock manufacturers, brake engineers and PSD suppliers. Monitoring stopping spots, the braking rate, and real data are the initial requirements for any further development and evaluation for a sound and stable train control system.
In the last three decades, train automatic stop control (TASC) algorithms have been developed and applied to different metro and heavy haul rail corridors all over the globe. However, even the most developed controllers have relied entirely on station markers such as home signals, on-the-track sensors or Balises. Although, position uncertainty has been considered in several studies before, it has been largely ignored in TASC studies so the foremost shortcoming of previously developed TASC algorithms is that they had not considered position uncertainty. The second most important problem with these algorithms for TASC is the exclusion of the inherent time delay in braking systems in response to any control signal.
Therefore, to consider those factors, a braking model for station stopping is developed in this thesis, which accounts for the time dependency of the train’s air brake system to improve the accuracy of the train’s stopping.
Finally, train position uncertainty, which is a missing concern in previous works, has been added to this thesis’s study.
... One way is to use model-based techniques, and the other way is to use signal-based techniques, in which signals are collected from track-based sensors and/or vehicle-based sensors. In this paper, we limit our discussion to vehicle-based sensors [5,6]. Various techniques are used to estimate unknown parameters for a good condition monitoring of railway vehicle including model-based techniques and signal-based techniques [7]. ...
This paper is about position estimation and fault detection under jamming fault for rail transportation system. The motivation is to improve the accuracy of the position estimator in real-world conditions, considering modeling errors, perturbations and expected faults. The approach is based on an unknown input observer used to estimate perturbations and detect jamming faults for a class of polytypic linear parameter-varying (LPV) system. Moreover, the mixed H∞/H_ approach is applied to help in the robustness of the fault detection via a residual. Offline experiments results are provided for illustration.
The accurate fitting of various parts inspected by measuring the width of the gap between two adjacent panels and the alignment of the two surfaces, known as flushness, is an important task in assembling vehicles. The optimal solution requires high accuracy and fast measurement. Toward this end, we develop a vision-based noncontact gap and flush measurement. The vision system consists of a high-resolution camera and a multi-line laser generator. The proposed gap and flush measurement sensor projects laser lines onto the panels that are observed by the high-resolution camera. The measurement is initiated when the operator brings the device closer to the surface until it is within operating range. During the process, the line features are digitized by using proposed approach, the desired calculations are made, the non-conforming images are discarded, and the remaining images are used to perform the gap and flush measurement. The measurement system can deal with complex surface in noisy industrial environment and achieve higher specifications compared with current gap and flush measurement sensors. The usefulness of the proposed system has been demonstrated using real tests with accurate know-size patterns and a real inline vehicle assembly system in Korea.
Precision stopping of an urban train at a station is prerequisite before starting revenue service due to screen doors. Regulation for precision stopping of the urban train requires ±30 cm in general in Korea. Since there is no device to detect stopping error automatically, it takes long time to gather stopping error data at each station due to manual measurement using a ruler. In this paper, we present a principle and design of a precision stopping measurement device (PSMD) which can be easily used for error detection of precision stopping of urban trains. The PSMD developed in our laboratory uses a non-contact optical laser sensor installed at the platform to generate pulse signals from vertical black and white patterns attached on a train side. The number of the generated pulses is counted using a microcontroller, and then is sent to a notebook computer on the train via wireless RF communication. The performance of the PSMD is tested at the lab experimentally under indoor and outdoor environments.
This paper presents the effect of pattern slot size on measurement results of a noncontact laser sensor, in which the noncontact laser sensor is used to measure a precision stopping error of a moving object at a specific position, and to send measurement errors to a main control station through ZigBee wireless communication. Measurement accuracies for various vertical slot sizes are tested experimentally using an actual device developed in our laboratory, and the validity of the device is demonstrated for a moving object on a rail experimentally.
Extrinsic calibration between a camera and laser range finder (LRF) is required to integrate information from both sensor. In this paper, we propose an improved algorithm of our earlier work [1] for the extrinsic calibration of a camera and laser range finder. We improve our previous algorithm in two directions. First, control points on laser range finder’s data are obtained by finding the crossing point of two fitted lines where previous algorithm directly used laser range finder’s data. It can reduce the effect of noisy measurement of laser range finder. Second, difference of distance on calibration plane is used as cost where previous algorithm used matching portion. Proposed algorithm gives an improved result than previous one. It is verified thorough experimental results. © 2015, Institute of Control, Robotics and Systems and The Korean Institute of Electrical Engineers and Springer-Verlag Berlin Heidelberg.
Navigation system for high-speed trains is necessary for increased operational safety and efficiency, new services for customers, and low maintenance cost. This paper proposes a high accuracy navigation system for high-speed trains based on a sensor fusion algorithm, with non-holonomic constraints, for multiple sensors, such as accelerometers, gyroscopes, tachometers, Doppler radar, differential GPS, and RFID, and a map matching algorithm. In the proposed system, we consider the federated Kalman filter for sensor fusion, where local filters utilize filter models developed for various sensor types. Especially, the local Kalman filter for RFID positioning, that is detected at irregular time intervals due to the varying train speed and RFID tag spacing, is developed to maintain high performance during GPS outage. In addition, an orthogonal projection map matching algorithm is developed to improve the performance of the proposed system. The performance of the proposed system is demonstrated with numerous simulations for a high-speed train in Korea. The simulation results are analyzed with respect to the existence of tunnel, RFID deployment spacing, RFID location uncertainty, and DGPS error.
Railway companies are encouraged to install platform screen doors (PSDs) for safety reason in Japan. The PSDs might affect train noises in stations, but the effects are not well understood. The aim of the present study is to clarify the effects of PSDs on acoustic characteristics. PSDs can be principally classified by two types, i.e., mobile full-height (MFH) and mobile half-height (MHH). Train noises were recorded in ground and underground train stations with MFH, MHH and without PSDs. The noises were evaluated by noise level, the maximum peak of the interaural cross-correlation function (IACC), and the width of the first decay (WΦ(0)) of the autocorrelation function. Noise level emitted by trains was reduced by PSDs in both aboveground and underground stations. IACC was decreased by PSDs in both ground and underground stations, suggesting that PSDs made train noises more diffused. WΦ(0) was decreased by PSDs in both ground and underground stations, which means that the train noises in station with PSDs have higher spectral centroid, suggesting that the PSDs blocked the lower frequency components of train noises.
Platform screen door (PSD) systems are starting to be popular in underground railway stations. However, there is a concern that PSDs would affect passenger movement during emergency, particularly during rush hours. In this paper, the effect of PSDs on emergency evacuation under crowded conditions will be studied. The characteristics of passenger flow in crowded subway stations in Hong Kong are surveyed. Evacuation times under different passenger loadings from a train vehicle are estimated by empirical equations using the data collected from the survey. Several scenarios with different opening conditions of PSD are considered. Results are useful for working out emergency evacuation strategies for crowded subway stations.
The concentrations of PM 10 and PM 2.5 were measured continuously in both indoors and outdoors of the Seoul Metropolitan Subway network, Korea from Oct. 2007 to Apr. 2008. As the platform screen door (PSD) system was installed in the end of 2007 (8e16 Dec. 2007), these PM data were analyzed for the evaluation of its effectiveness on the control of PM levels. The results indicated that the mean PM 10 concentration in the later period (after PSD installation) was significantly reduced by 16% relative to the earlier period. In contrast, in the case of PM 2.5 distinctions were not statistically significant despite a 12% reduction (P < 0.05). The overall results of this study suggest that the installation of the PSD and ventilating system should have served as one of the important components for maintaining the air quality in the model subway system.
Coded 24 GHz Doppler sensors have been realized to perform
high-precision non-contact vehicle position and speed measurements.
Encoding the radar signal with a spread-spectrum code is the key to a
significantly enhanced sensitivity combined with a range selectivity of
the sensor. The novel system concept establishes a high-performance
low-cost vehicle Doppler radar system with very high measurement
accuracy suitable for automotive and railway applications
In this paper, we propose a vision-based object detection algorithm for railway passengerpsilas safety. The proposed algorithm uses three-dimensional position information with stereo cameras for minimizing various illuminant effects in railway platform environment, such as ambient illumination changes due to train arrival/departure in the scene. The detection process analyzes scene and detects both four different train status and fallen objects in preset monitoring area. To solve the detection problem in conventional two-dimensional detection system, the system detects object in three dimensionally by using stereo vision algorithm. We verify the system performance with extensive experimental results in a metro station. We expect the proposed algorithm will play a key role in establishing highly intelligent monitoring system for passengerpsilas safety for future railway environment.
The 6-axis force transducers based on the Stewart platform require the solution of forward kinematics of the Stewart platform in order to obtain force and torque acting on the upper plate from given six leg forces. However, the solution of forward kinematics is not known in a closed form. In this paper, a closed-form solution of the forward kinematics is derived by means of linearization of the inverse kinematics equations, and the derived solution is applied to the calculation of force and torque acting on the transducer. In order to investigate the validity of the proposed method, a prototype of the transducer based on the Stewart platform is developed and force analysis is conducted. Moreover, the gravity compensation algorithm is proposed to reduce the weight effects of the transducer.
Contenido: Introducción a la mecatrónica y sistemas de medición; Circuitos eléctricos y componentes; Semiconductores electrónicos; Sistemas de respuesta; Procesamiento de señales análogas usando amplificadores operacionales; Circuitos digitales; Programación de microcontroladores e interfaces; Adquisición de datos; Sensores; Actuadores; Sistemas mecatrónicos (Arquitectura del control y estudios de caso); Apéndices.
Automatic train control plays a key role in improving the
efficiency and safety of train movements, as well as the riding comfort
of passengers. In Japan, train control systems have been successfully
implemented since 1980s. These systems are required to control the train
position and speed as accurately as possible. This is mostly dependent
on the axle generators and transponders. More specifically, the axle
generators measure the speed and moving distance from the reference
points specified by the transponders. However, the train control systems
using these devices still fail to achieve a correct train position, due
to skidding or slipping, until passing over reference points. This paper
focuses on the train automatic stop control (TASC), and presents a new
TASC system using a commercial range sensor instead of transponders so
that the train equiped with the system can detect its position
continuously
The method and device of train stop position detection
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he worked as research engineer at Shalom Engineering Co. His current research interests are precise stopping control, signaling and braking of railway vehicles, force control of robots
- Ho-Yeon
Ho-Yeon Kim received his B.S. degree in
Electronic Engineering from Daejin University in 2005, and his M.S. and Ph.D.
degrees in Mechanical Engineering from
Konkuk University in 2008 and 2016, respectively. From Oct. 2010 to Sep. 2014,
he worked as research engineer at Shalom
Engineering Co. His current research interests are precise stopping control, signaling and braking of railway vehicles, force control of robots, advanced control theory and application, and safety certification.