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Disturbance Estimator Based Event-Triggered Control

Posted on:2016-07-04Degree:MasterType:Thesis
Country:ChinaCandidate:T S MaFull Text:PDF
GTID:2308330473463099Subject:Control Science and Engineering
Abstract/Summary:PDF Full Text Request
With the development of network technology, communication networks have been widely implemented in distributed control systems, such control system is named networked control systems(NCSs). In NCSs, communication networks are employed to exchange information among the sensors, controllers and actuators. It is naturally to know that to high the communication frequency will result in better control performance. However, higher communication frequency will increase the network load, which may lead to network congestion, and thus degrades the system performance or even destabilizes the system at certain conditions. Therefore, how to reduce communication requirements on networked control systems is an interesting and important problem which should be considered.In the last decades, event-triggered control (or named event-driven control) has attracted considerable attention. In the event-triggered control system, the information exchange is triggered by some predefined event which is often chosen as some function of the system state exceeds a threshold. In this situation, the updating of control signal will be employed only the "necessary" information should be transmitted, thus the communication frequency is relatively low, and the change of the input signal is relatively infrequent which means a lower load and a longer service life of the actuator. On the other side, in NCSs, besides the external disturbance, time delay or packet dropouts could also be taken as disturbance, so how to handle the disturbance plays an important role in NCSs, it’s significant to consider the disturbance estimation problem. In our work. The disturbance estimator based event-triggered control strategy will be taken into consideration.For a real system, the existence of external disturbance is often an inescapable problem. In NCSs, time delay or packet dropouts could also be taken as disturbance. We will consider the event-triggered output-feedback control for plant with unknown external disturbance. And the estimate value will be used to compensation the disturbance. Relatively good control qulity is achieved with the help of disturbance estimator in event-triggered control.Besides, event-triggered control strategy itself may take extra uncertainty to the system since some imformation of the control system will not be transported. Such uncertainty is also able to be equally regarded as some disturbance. And two parts of such problem will be considered:event-triggered control basing on sampled output and disturbance estimator based periodic event-triggerd control. We take the error caused by sampling and periodic event-triggerd control as unknown disturbance. And the disturbance estimtor approach is implemented to handle the disturbance which acquires a much better observation accuracy and control qulity then a Luenberger observer.In this paper, we aim to propose several forms of disturbance estimator based event-triggered control strategy. With the help descriptor observer approach, both the state and disturbance could be estimated synchronously, and the event-triggered controller will be designed basing on the estimate value. Some significant improvements of event-triggered control strategy will be given.
Keywords/Search Tags:networked control system, event-triggered control, disturbance estimator, descriptor observer
PDF Full Text Request
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