Research On Multi-sensor Fusion Algorithn For Train Positioning And Safety Assessment

Rail transportation is one of the most important public transport due to its high safety,reliability,large transportation,low energy consumption,and low pollution.Train control system is essential to ensure the safety and efficiency of train.The measurement of speed and position is the key technology for the train control system.The accuracy of positioning plays an important role in guaranteeing the safety and reliability of the train.The thesis presents a novel information fusion algorithm for multi-sensor integrated speed and position measurement scheme based on the modeling of sensor errors.In order to eliminate non-Gaussian noise of wheel sensor in braking phase,particle filters are applied to estimate train speed with wheel sensor and Doppler Radar sensor.Estimation accuracy of particle filter is effected by proposal distribution dramatically.Therefore,bird swarm algorithm is adopted in particle filter to optimize the proposal distribution.Simulation and experimental results prove that the presented particle filter shows better performance than conventional particle filters and other nonlinear filters.Safety analysis of the integrated positioning system is introduced.Failure mode and effect analysis are used to identify the sources of the system hazards.Fault tree has been established based on the detailed analysis of different failure modes of the system.The dangerous failure rate of the top event is calculated.Furthermore,a dynamic state space transfer model based on Markov chain is set up for the presented system.Dangerous failure rate of the system is obtained by calculating the steady-state solution of the Markov chain.The results of the safety assessment show that the proposed scheme achieves safety integrity level SIL4.Finally,a simulation system of the train integrated positioning system is developed on MATLAB,which can evaluate the performance of the system.The research achievement of the thesis lays the foundation for further implementation of multi-sensor train speed and position measurement system as well as the application of speed and position measurement technology based on multi-sensor.