In this article, the dynamic event-triggered model-free adaptive security tracking control problem of the subway system with speed and traction/braking force constraints under aperiodic denial-of-service (DoS) attacks is studied. The complex subway train system is transformed into a linearization data model by using the dynamic linearization technique. For the subway system, both speed and traction/braking forces need to be restrained to ensure the safety of the subway equipment. In addition, the dynamic event-triggered mechanism is designed to reduce communication frequency and prolong the hardware life cycle. At the same time, considering aperiodic DoS attacks in the network channel, the security tracking control problem is guaranteed. In the simulation, the algorithm is applied to the subway train system, and the effectiveness of this algorithm is verified with a comparison.
K E Y W O R D Saperiodic DoS attacks, constrained subway train system, dynamic event-triggered mechanism, model-free adaptive control
INTRODUCTIONWith the emergence of technologies in the field of the network, such as the big data processing technology and the cloud computing technology, it further promotes the development of cyber-physical systems (CPSs). 1,2 The system uses the unlimited data and information resources of the network system to break through the limitations of the physical resources. The intelligent transportation system is one kind of CPSs, 3 among which subway train system has been widely concerned.Compared with the ordinary train, the subway train control may have a series of new challenges, such as network attacks and excessive data transmissions. Attacks on the network may affect the stability of the train operation and even endanger passengers safety. A large amount of data will be generated during the train operation, which leads to extremely high calculation costs. All of the above issues need to be thoroughly studied and discussed.Considering that data generated by trains may encounter many problems when transmitted over network channels, such as attacks, packet loss and so on. [4][5][6] Although there are so many problems with the transmission over the network, one of the problems that affect the system most is the network attack. There are two main types of attacks: denial-of-service (DoS) attacks and false data injection (FDI) attacks. 7,8 Research on DoS attacks has been studied for many years. 9-16 DoS attacks are usually handled in three ways: detection attacks, resistance attacks, and compensation attacks. A model was designed to evaluate the effect of DoS attacks, 9 which can not only evaluate individual attacks, but also can rank the effects of attacks. An active security attack strategy for the two-channel attacks was designed by taking full advantage of Abbreviations: DET-MFASTC, dynamic event-triggered model-free adaptive security tracking control; DoS, denial-of-service; PPD, pseudo-partial derivative.