A High Precision Position Sensor Design and Its Signal Processing Algorithm for a Maglev Train

Abstract

High precision positioning technology for a kind of high speed maglev train with an electromagnetic suspension (EMS) system is studied. At first, the basic structure and functions of the position sensor are introduced and some key techniques to enhance the positioning precision are designed. Then, in order to further improve the positioning signal quality and the fault-tolerant ability of the sensor, a new kind of discrete-time tracking differentiator (TD) is proposed based on nonlinear optimal control theory. This new TD has good filtering and differentiating performances and a small calculation load. It is suitable for real-time signal processing. The stability, convergence property and frequency characteristics of the TD are studied and analyzed thoroughly. The delay constant of the TD is figured out and an effective time delay compensation algorithm is proposed. Based on the TD technology, a filtering process is introduced in to improve the positioning signal waveform when the sensor is under bad working conditions, and a two-sensor switching algorithm is designed to eliminate the positioning errors caused by the joint gaps of the long stator. The effectiveness and stability of the sensor and its signal processing algorithms are proved by the experiments on a test train during a long-term test run.

A Study on the Sensor Applications for Position Detection and Guideway Monitoring in High Speed Maglev

“…As this equation implies, since value ( ) S t includes only the relative information about guideway irregularity profile, by subtracting the absolute vehicle movement value ( ) B t ∬ , the real profile of guideway could be achieved. To avoid the drift effect during integration of acceleration, the further signal processing procedures such as high pass filter and phase advance are additionally necessary [6].…”

“…Therefore, the performance of position detection sensor should be guaranteed under various environments [3]. Moreover, since the detected data should be wirelessly transmitted to the ground control station located in several kilometer away, specialized data process technique is needed to avoid the problem caused by signal delay and transmittance cycle [4]- [6].…”

Switching Algorithm for Maglev Train Double-Modular Redundant Positioning Sensors

“…Let p h ( k ) denote the current phase value and n ( k ) denote the current tooth-slot period number. Considering a tooth-slot period corresponds to a phase angle of 60°, the converted signal is calculated as follows [10]: $p_{ha}(k)=60n(k)+p_h(k)$…”

“…The spike pulses can be eliminated through simple logical pretreatment [10]. As the spike pulses are about 60°, so they can be identified by detecting the difference value of the adjacent sampling phases.…”

Speed Calibration and Traceability for Train-Borne 24 GHz Continuous-Wave Doppler Radar Sensor

“…Meanwhile, many big cities of China have begun to extensively construct railway passenger dedicated lines in urban, suburban, and intercity areas in recent decades. Speed surveillance is a key component of a railway management system for automatic train control in railway passenger dedicated lines to ensure the operation safety and high efficiency of rail transits [1][2][3][4][5]. A train speed surveillance system generally relies on a combination of a track-side fixed subsystem and a train-borne movable subsystem to calculate the instantaneous speed and covered distance of trains in China.…”