Research On Velocity Tracking And Adhesion Anti-slip Control Strategies For High-speed Trains

Automatic train operation(ATO)technology is one of the research hotspots in the field of rail transit,and it is closely related to the operation efficiency and performance of the entire railway system.At present,the research on ATO technology mainly focuses on two issues:The optimization of target velocity profile,and the control methods for train velocity tracking.The optimized velocity profile can be calculated and obtained considering the requirements of energy saving,punctuality,comfort,safety and so on.Then,the key to achieve desired train operation performance index is to design an effective train velocity tracking control strategy to realize accurate tracking to the optimized profile.Therefore,it is of great theoretical and practical significance to explore the velocity tracking control strategy of high-speed trains(HSTs)and improve the tracking control performance.The dissertation focuses on the velocity tracking control issue of HSTs.The velocity tracking control strategies of HSTs are intensively investigated using dynamic surface method,sliding mode control technology,adaptive control technique,Lyapunov's stability theory and so on.Adhesion anti-slip control issue of HSTs is also researched and an active adhesion anti-slip control algorithm is put forward to avoid wheel idling and skidding in train velocity tracking operation,which would reduce train tracking accuracy and reliability.Aiming at the velocity tracking control problem of HSTs in the process of automatic train operation,the train velocity tracking control strategy considering traction/braking dynamics is discussed.In the dissertation,dynamical model of HSTs considering traction/braking dynamics is established,the extended state observer(ESO)technology is used to observe the lumped uncertainty of the system,and the model parameter estimation method based on adaptive updating law is introduced,based on which the dynamic surface tracking control strategy for HSTs is developed to avoid the drawback of large amount of calculation when using conventional backstepping method;To further improve the tracking performance of the system,train velocity tracking control strategy based on improved dynamic surface is investigated;On this basis,an additional system dealing with input constraint is constructed,and a velocity tracking control strategy for HSTs with input constraint is presented.The system performance degradation or instability due to actuator output saturation or wheel idling/skidding,which is caused by too large control input,can be handled.In view of the fact that most velocity tracking strategies of HSTs subject to actuator faults do not take the actuator output saturation constraint into consideration,the fault-tolerant tracking control issue is researched for HSTs considering actuator faults,output saturation constraint,additional resistance and time-varying uncertainties of model parameters.The adaptive technology is introduced to estimate the nominal value of model parameters,the gains of the PID-type sliding mode surface and the upper bounds of the system lumped uncertainty.An additional signal is constructed to deal with the actuator output saturation.On these basis,a fault-tolerant tracking control strategy using variable-gain proportion-integral-derivative(PID)-type sliding mode surface is designed and accurate tracking control performance of HSTs under the influence of multiple factors is achieved.In order to further improve the tracking accuracy and convergence speed of the system,a fault-tolerant tracking control strategy based on nonsingular terminal sliding mode(NTSM)surface is addressed.To actively avoid the wheel idling and skidding of HSTs in tracking operation and provide adhesion force meeting the requirements of traction/braking,the adhesion anti-slip issue is investigated based on dynamical model of HSTs considering traction/braking dynamics and anti-slip constraints.Force observer theory is adopted to observe the unknown time-varying adhesion force and running resistance.The parameters of the model are estimated by adaptive control technique.The barrier Lyapunov function(BLF)is introduced to constrain the upper bound of slip velocity.On these basis,a dynamic surface adhesion anti-slip control algorithm based on slip velocity tracking is put forward to tackle the wheel idling and skidding.The stability of the closed-loop system is analyzed and proved based on Lyapunov's stability theory,and numerical simulation is performed to verify the feasibility and effectiveness of the proposed velocity tracking control strategies and adhesion anti-slip control algorithm.The results show that the velocity tracking control strategies achieve accurate tracking to the target velocity optimization profile of HSTs,and the adhesion anti-slip control algorithm realizes global active adhesion and anti-slip control in train velocity tracking operation.They can guarantee the realization of train operation performance index and ensure the reliable and safe operation of HSTs.