Multi-model Adaptive Time Delay Control For Braking Process Of High-speed Trains

In recent years,high-speed train has become one of the mainstream transportation tools in China for its unique advantages such as fast running speed,high passenger capacity and low energy consumption.With its rapid development,the reliability and safety of its operation have attracted increasing attention.At present,the main means of braking and stopping a high-speed train is adjusting the brake handle manually by the driver,which is low automatized and requires the driver to have rich driving experience.In addition,the uncertain factors that exist during the actual braking such as complex track conditions,variable operation environments and unknown input time delays will have an impact on the braking effect and stopping accuracy of the train.Therefore,in-depth research on modelling and control methods of high-speed train braking processes to achieve safe and smooth braking of high-speed trains has become one of the important topics in the field of rail traffic control.This thesis takes the high-speed train braking system as the research object and conducts an in-depth study on its speed tracking control problem.After analyzing the principles and characteristics of the train braking process in detail,a mathematical model of the high-speed train braking system considering the unknown input delay is first established in consideration of the actual train braking situation.Then,the brake controller is designed using the multimodel adaptive control strategy.Further,the train braking system model considering unknown faults is developed and a multi-model adaptive fault-tolerant control strategy is proposed,considering the brake control device actuator fault in the braking system caused by the increasing on-track time of high-speed trains.Such a scheme ensures safe braking of trains even in pesence of unknown brake system failures.The research contents and innovation achievements of this thesis are as follows.Firstly,the related principle of the high-speed train braking process is studied,and the dynamic characteristics of each working link of the electric-air hybrid braking system are analyzed.The model of high-speed train braking system considering the unknown input delays is established after fully considering the characteristics of delays in the braking force signal transmission process.Secondly,a multiple-model adaptive braking control scheme is designed to solve the problems of unknown input delays and parameter uncertainties in the braking process of highspeed trains.Such a control scheme can solve the problem of unknown input time delays by introducing the idea of multiple models and employing the special advantage of adaptive control to overcome the uncertainties of system parameters.Both theoretical proof and simulation experiments show that the designed control scheme has desired braking performance and control accuracy.Thirdly,considering the failures of brake control device actuator in high-speed train braking systems,a high-speed train braking system model with unknown failures is established under the assumption that the imput time delay is known.Furthermore,a new multiple-model adaptive fault-tolerant control scheme is proposed,and the associated theoretical proof of system stability is given.The simulation results verify that the designed multiple-model adaptive fault-tolerant control strategy can achieve the asymptotic tracking of the given braking curve in the case of unknown actuator faults,and ensure the safe and smooth braking of trains.