Robust Fault-Tolerant Control For NCS Based On Discrete Event-Triggered Scheme

The Networked Control System(NCS) is a distributed control system, where the data information, communication network and closed-loop feedback control are synthesized. Due to the influence from the large structure, network-induced delay and packet loss arising from limited bandwidth, the reliability and safety of the NCS is facing new challenges. Therefore, the fault-tolerant design for NCS has received considerable attention. However, the existing research results are based on "Time-triggered" communication schemes, meanwhile, the fault tolerant design is isolated. Although the complexity of the system analysis is reduced, it lead to large computation capability and wasting of communication resources. When dealing with busy networks, using this scheme for NCS will aggravate the delay and packet loss which can deteriorate system performance. In the practical engineering, the data transmission from the sensor to the controller and from the controller to the actuator should only occur when the related information needs to be transmitted. Then, how to reduce transmission of the sampled data as little as possible under ensuring the system performance and safe working, which become an important issue for fault-tolerant control of NCS currently.In view of this, the discrete event-triggered communication scheme is introduced in this paper firstly. Then, the robust fault-tolerant control for discrete event-triggered uncertain NCS is studied using the state feedback strategy. Time-varying delay, parameter uncertainties, more generally actuator failures are taken into account simultaneously. By virtue of the Lyapunov stability theory, improved Jensen inequality and LMI, the co-design method for both robust fault-tolerant controller and communication trigger parameters is given considering the multi-objective constraints of α-stability, H∞and H2. This paper studied uncertain NCS robust fault-tolerant control problem under the event-triggered communication schemes, Besides, the co-design method of fault-tolerant controller and communication trigger parameters is given. The main work include the following aspects:1) A closed-loop fault NCS model is established based on discrete event-triggered communication schemeFor a networked control system with time-varying delay, considering parameter uncertainties and more generally actuator failures. Based on state feedback control law, making the NCS network properties, failure modes and trigger conditions unified together, under the discrete event-triggered communication scheme, a closed-loop fault model of NCS is established.2) Robust fault-tolerant control research for a uncertainty NCS under discrete event-triggered communication schemeBased on discrete event-triggered communication scheme, for a networked control system with time-varying delay, considering parameter uncertainties and more generally actuator failures. Making use of Lyapunov stability theory, improved Jensen inequality and LMI, the sufficient conditions of a less conservative are obtainted for system with robust integrity, robust H∞fault tolerant and robust generalized H2/H∞fault tolerant, and a co-design method for fault tolerant controller and communication resources share is given by solving linear matrix inequalities approach.3) Robust satisfactory fault-tolerant control research for a uncertainty NCS with α-stability under discrete event-triggered communication schemeUnder the constraint of α-stability, based on discrete event-triggered communication scheme, for a networked control system with time-varying delay, considering parameter uncertainties and more generally actuator failures. Making use of Lyapunov stability theory, improved Jensen inequality and LMI, the sufficient conditions of a less conservative are obtainted for system with α-stability robust integrity, robust H∞fault tolerant and robust generalized H2/H∞fault tolerant, and a co-design method for fault tolerant controller and communication resources share is given by solving linear matrix inequalities approach.4) The the validation of Correctness and effectiveness of the controller design, and the impact analysis of trigger parameters for communication resource utilization and system performanceSimulation cases of the above research conclusions are given in the paper. The results show that the proposed approach can not only ensure failure system keep stable, but also can save network resources effectively. In other words, it can provide a tradeoff to balance the system performance and required network resources. Furthermore, it achieves the co-design between fault-tolerant controller for NCS and communication resources usage, at the same time, taking into consideration of the QoS and QoC. The introduction of multi-objective constrains improve the fault-tolerant satisfaction of the NCS. Besides, in the process of proof, any free-weighting matrices are not employed, instead of using an improved Jensen inequality deals with some of the integral term, such that the conservative of conclusion and the complexity of calculation are decreased. It provides not only the broad solution space for the fault-tolerant controller with high level of satisfaction, but also the convenient design.