High-Speed Train Tracking Control Based On Fractional-Order Controller

With the high-level and large-scale construction of high-speed railways,China's high-speed railway has become a bright world business card.Railway safety is related to the safety of passengers ' lives and property.Therefore,ensuring the safe and reliable operation of trains is the fundamental prerequisite for the development of high-speed railways.Automatic Train Operation(ATO)system plays an important role in ensuring the reliable and stable operation of trains.Especially,adopting advanced high-speed train automatic driving control algorithms is one of the most effective ways.As the running speed of trains increases,passengers have higher requirements for the safety,stability and riding comfort of high-speed trains.Therefore,improving the control accuracy,anti-interference ability and robustness of the controller has become the key to study the tracking control problem of high-speed trains.Based on the development needs of high-speed train automatic driving technology,this paper applies the fractional calculus theory to the speed and displacement tracking control of high-speed trains.Combined with the existing control methods,a kind of fractional-order control strategy is proposed,which can effectively improve the system control performance and meet the control requirements of high-speed trains for operation stability and parking accuracy,and can simultaneously improve the passenger comfort.The main research work of this paper is as follows:Firstly,this paper considers the asymmetric saturation characteristics of high-speed train traction / braking actuators,and carries out detailed dynamic modeling of high-speed train as non-affine system.The study comprehensively considers the influences of nonlinear control inputs,time-varying parameters,unknown resistance,unknown in-train force,and actuator failures during the actual operation of high-speed trains,and establishes the non-affine multiple point-mass model for high-speed trains.Besides,the non-affine nonlinear characteristics of the system are specifically analyzed and processed,which lays the foundation for the subsequent design of effective tracking control strategies.Secondly,considering that the integer-order is a special form of fractional-order,the paper first establishes an integer-order-based adaptive and fault-tolerant tracking control algorithm to achieve asymptotically stable tracking of speed and displacement of high-speed trains.Then,based on the integer-order control method,the fractional calculus theory is applied to establish the fractional-order tracking control strategy to further improve the control accuracy,anti-interference ability and robustness of the controller,so as to achieve the control objective of higher tracking precision of high-speed train speed and displacement,improve the system control performance and ensure passenger comfort.The established control methods do not depend on the specific model parameters of the system and have the capacity of fault-tolerance.They can ensure the stable operation of high-speed trains under the influences of system nonlinearity and uncertainty.Finally,this paper specifically analyzes the traction and braking dynamic characteristics of high-speed trains which are ignored by most research,establishes a new multiple point-mass and single-coordinate model of high-speed train with electrical structure,and designs fractional-order traction/braking and unified traction and braking tracking control strategies for high-speed trains with the terminal voltage of the traction/braking device as the control variable.The research is supported by fractional calculus theory,combined with adaptive and backstepping control techniques,while effectively compensating for the uncertainties in the system,and ensuring that the controller has stronger anti-interference ability and robustness,and can meet the requirements of high-speed train tracking control.