Active-passive Hybrid Fault-tolerant Control Research Of Linear Networked Control System Under Event-trigger Mechanism

Networked control systems(NCSs) are space distributed control systems in which sensors, controllers, actuators and other system components are connected via a limited digital communication network. In actual NCSs, there are always exist uncertainty due to different kinds of reason, in addition to this, some inevitable problems would also appear while transmission of information, what’s more, as constituent part of control system, actuators or sensors could break down at any time, which all might be potential causes for the performance deterioration or even the instability of the NCSs. So introduce fault-tolerant control technology to the research of security and reliability of NCSs has recently attracted considerable research attention.Fault-tolerant control fall into two major categories: Passive Fault-tolerant Control(PFTC) and Active Fault-tolerant Control(AFTC), PFTC use robust control technology to make the system faults-insensitive, but this way is highly conservative because of the same control gains is used all the time, no matter the system is normal or fault. AFTC is a way to tackle the problem through diagnosis the fault online, using active or passive diagnosis, and then re-design the controller for the faulty system, since it cost time to estimated faults and re-design controller, AFTC has a bad realtime performance. In Discrete event-triggered communication scheme(DETCS), the event-triggered condition has given already, the system decides whether to transmit information or not via judge whether the condition is supported, whereas the primary cause of network induced delay is bandwidth constraints, introduce DETCS into system control can reduce communication loads apparently as well as keep system stable. At present, researches aimed at fault-tolerant control of NCSs under DETCS mainly concentrated on PFTC and the design of filter. In order to save network resource, the design of a hybrid controller which combined the advantage of AFTC and PFTC under DETCS may become the mainly direction of our research.Take all the conditions into consideration, the thesis deals with the event-triggered active-passive hybrid robust fault-tolerant control problem under actuator any failure in linear NCSs with time-varying delay. Generally overview as follows:1) Research active-passive hybrid fault-tolerant control of linear nominal NCSs based on independent event generator.First of all, aimed at linear nominal NCSs with time-varying delay, a fault system model is subsequently established based on independent event-triggered scheme, and a passive fault-tolerant controller is designed to keep the system stable when faults in the sets occurs. At the same time, fault diagnosis observer is designed to estimate the size of actuator failure faults, the controller will be re-construct immediately to compensate the influence of faults once accuracy fault information has got.2) Research active-passive hybrid fault-tolerant control of uncertain linear NCSs based on event-triggered schemeAimed at linear uncertain NCSs with time-varying delay, build NCSs fault model based on DETCS as well as robust fault detect observer on account of H_∞ control theory; In addition to it, we also designed robust fault-tolerant controller off-line so that the system could keep stable when the fault which is known before occurs, and slow down the speed of system performance decline in the initial stage of unknown failure; simultaneously, make good use of robust fault detect observer to realize fault on-line detecting, and re-construct controller so that it can compensate the influence caused by unknown fault.3) Research of Active-passive switch H_∞fault-tolerant control of Uncertain linear NCSs under Evet-triggered schemeAimed at uncertain linear NCSs with time-varying delay, under the influence of norm-bounded exogenous disturbance, normal controller and passive robust H_∞ fault-tolerant controller is designed respectively under DETCS so that the system could possess good dynamic performance during normal operation of the system. When faults occurs, the system will switch to passive robust H_∞ fault-tolerant controller via transient switching function, which assured the system not only stable but also have certain H_∞ disturbance restrict performance when known failure happens, and decrease the decline speed of system performance at the early stage of unknown faults; besides, robust H_∞ fault detect observer which make use of adaptive compensate control technology to eliminate the influence of unknown faults is designed to detect faults in real-time.4) Based on the above research, the simulation shows that the resultant closedloop fault NCSs possesses an improved dynamic performance, as well as a reduced communication load.The simulation shows that introduce the event generator to sensor has realized the integrated design of fault estimation of NCSs and active-passive hybrid fault-tolerant control, as well as a reduced communication load. The method of fault detect based on observer which has mentioned in this paper could diagnosis any failure effectively, the active-passive hybrid fault-tolerant controller we have designed proposes different control theory while different times in system operating, which made the whole system always possess good performance no matter in normal time or any actuator failures occurs.