Research On Braking Of Railway Heavy-Haul Train Based On Fuzzy Sliding Mode Control

With the establish of China fast railway network and urban rail transit network in recent years,the heavy-haul technologies have been to the important stage.Because of the Chinese first intelligent drive of freight train running in Shenhuang railway in 2019,heavy-haul freight train has the process of intellectualization.Due to the improvement of speed and axle load,one of the major researches is to ensure the safety of heavy-haul train baking process,improve the anti-interference capability and control accuracy of controller.In order to improve the transport efficiency of heavy-haul train and ensure the safety of train operation,this thesis focus on the generation of speed protection curve and the design of heavy-haul train brake.The excessive longitudinal force of coupler has a very bad effect on raising operation speed and the safety of braking during heavy-haul train operation,which mainly causes by the delay of train braking in different components resulting in car body structure squeezing coupler.The traditional method of collecting coupler force is time-consuming and labor-intensive through braking characteristics experiment.Therefore,in order to obtain the coupler force of heavy-haul train on different railway lines,Newmark-β method is applied to simulate and analyze longitudinal force of coupler.Heavy-haul train and its operation environment constitute a complex nonlinear system,the traditional methods of solving longitudinal dynamic equation use too much iteration to ensure accuracy,which are time-consuming and inefficient.In this thesis,the improved Newmark-β method achieving the simulation of coupler force bases on the increment,which introduces the predictive solution to solve the nonlinear equation directly that omitting the approximate linearization process of the nonlinear equation,and the change of the predictive solution adopts bisection method to quickly close to convergence.Based on the multi-segment linear model of coupler buffer of railway freight train,the longitudinal force of train in operation is analyzed and the multi-particle model of heavy-haul train is established.To simplify this model,trains with the same line parameters are regarded as a group and the different groups are connected through coupler buffer.Based on the principle of speed protection curve,the motion state of each particle and the change of coupler force can be obtained by the improved Newmark-β numerical integration method.Combined with the actual line data of Xinzhun railway,the speed protection curve of heavy-haul train is generated.Compared with the simulation result of the single-particle,the protection curve of the multi-particle model is more line with the actual operation conditions in braking distance,braking starting point and the change of acceleration during braking applied to adjust speed and stopping braking,which meets the safety requirements of one-step braking of heavy-haul train.The speed protection curve of heavy-haul train is an important reference to ensure the safety train operation in the process of train braking.Once the speed over the limit of curve,it may cause serious accident such as overrunning of signal and rear-end collision.Safety and efficiency are two important targets of heavy-haul train,which is different from passenger train.Therefore,this thesis considers tracking the braking process of speed protection curve under the maximum service braking of the train.The operation environment of heavy-haul train is special and exists a lot of complex disturbance factors,however the stability and the anti-interference capability of sliding mode control are outstanding,so sliding mode control is selected as the brake.The numerous nonlinear disturbance factors in train operation can be solved by switching the control quantity to compensate it and introducing fuzzy logic to fuzzified the switching control.The simulation results shows that the fuzzy sliding mode control brake can make heavy-haul train accurately track the speed protection curve to brake,and the fuzzified switching can reduce the influence of chattering to a certain extent,which ensure the safety of heavy-haul train braking and the operation efficiency is maximized.