Compatible Traction/Braking Control Based On Wheel Rail Wear Reduction And Optimization

High speed train(HST)is an important means of transportation in China.The safety and comfort of its long-term operation is a precondition for the sustainable and global development.Reducing the wear and fatigue damage of wheel-rail system is an effective way to improve the safety and comfort of HST.At present,the research on optimizing the wheel-rail physical parameters(e.g.track gage,wheel profile,surface hardness,etc.)to reduce the overall wear of the train has been quite mature,but the research on partial wheelsets wear caused by wheel skid and differences of actuators during the operation is rare.Wheel skid will lead to severe wear or fatigue damage,and small persistent differences of skid velocities due to different actuation effectiveness of actuators may lead to severe nonuniform rolling wear or fatigue damage of a part of actuation wheelsets after long-term operation.Therefore,it is of great significance to reduce wheel-rail local wear during train operation.In this thesis,the optimization of wheel-rail local wear is studied from two aspects: preventing wheel skid actively and compensating possible actuators differences.The main contributions are listed as follows:(1)At the moment,most researches on anti-skid aimed at separating the targets of anti-skid constraint and velocity tracking,and anti-skid issue is rarely incorporated into a unified compatible framework with traction/braking control design since adhesion control and traction/braking control are usually considered as two independent processes.In this work,an active anti-skid constraint based adaptive traction/braking control scheme is developed innovatively,in which the antiskid boundary condition is directly introduced into traction/braking control design.The creep rate of wheel-rail system never exceeds a given empirical anti-skid boundary which can be freely selected near theoretical value during the whole traction/braking process when applying the proposed controller,at the same time precise velocity tracking is guaranteed.Then,a Lyapunov equation with anti-skid constraint and velocity tracking error is designed,and the validity of the control scheme is verified by theoretical proof.(2)For nonuniform wheel wear caused by the different actuators of HST,this paper firstly verifies that the differences of actuators will generate different wheel angular velocity,and then lead to nonuniform wheel wear.Secondly,a hybrid dual loop control framework combined traction/braking control and wheel angular velocity synchronouscontrol is designed,in which uncertain parameters are identified by robust adaptive observers.It is shown that with this controller,not only the common objective of traction/braking operation is achieved,but also actuators differences are completely compensated such that the same skid velocity(implying uniform driving load and rolling wear)is ensured for all actuation wheelsets during long-term operation.The validity of the controller is proved theoretically.Finally,the two control schemes are both simulated in MATLAB,and compared with the general control schemes,respectively.The results show that the antiskid constraint traction / braking control scheme proposed in this paper can realize train velocity tracking and antiskid constraint at the same time;and the wheelsets cooperative traction / braking control scheme can realize train velocity tracking and wheelsets wear equalization at the same time too.The control performance of the two schemes are better than the corresponding general controllers.