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Networked Control And Filtering For Nonlinear Systems Based On Fuzzy Models

Posted on:2015-06-18Degree:DoctorType:Dissertation
Country:ChinaCandidate:X B ChiFull Text:PDF
GTID:1108330461985154Subject:Basic mathematics
Abstract/Summary:Request the full-text of this thesis
One of the development trends of an industrial control system is to integrate the digi-tal sensors, communication devices, network, and intelligent computers into the closed-loop control system. Comparing with conventional point-to-point control systems, the advan-tages of the network-based control systems are the lower cost, greater agility of control framework and ease of installation and maintenance, etc.. With the rapid development of digital sensing technology and network technology, networked control systems (NCSs) have been finding application in a broad range of areas, such as industrial control processes, intelligent transportation systems and so on. In the practical applications of NCSs, the controlled plant is usually nonlinear, there exist analog signals and digital signals simulta-neously, the network bandwidth is limited, and networked-induced delays and data packet dropouts often occur. Therefore, it is of theoretical significance to investigate these prob-lems. In this dissertation, the design problems of control and filtering for the nonlinear NCSs will be investigated by using the T-S fuzzy modeling method. The main contri-butions include the following two aspects:1) the network-resource-saved event-triggered transmission schemes are designed for improving the operating mechanism of NCSs; 2) by considering the effect the membership functions in NCSs on system performance, the mem-bership function deviation approaches are proposed to design networked fuzzy controller and networked fuzzy filter for nonlinear systems, respectively. The research contents and results are as follows:(1) Networked stochastic H∞ control and networked tracking control are investigated for the nonlinear systems which can be described by discrete-time T-S fuzzy models, respectively. In the problem of stochastic H∞ control, the data packet dropouts are described by a stochastic sequence satisfying a Bernoulli distribution. Then, the nonlinear NCS is modeled as a T-S fuzzy system with stochastic parameters. In the problem of tracking control, the networked tracking error system is modeled as a discrete-time delay system by using the discrete input delay approach. Based on Lyapunov stability theory together with a improved H∞ performance, the design methods of the fuzzy controller and the fuzzy tracking controller are presented in terms of LMIs, respectively. The relation between the non-zero initial condition and the H∞ performance is established.(2) The design of sampled-data guaranteed cost fuzzy control is investigated for a class of nonlinear systems with control input constraints and the time-varying sampling way, where the nonlinear systems are described by continuous-time T-S fuzzy models. Consider-ing the control input constraints, a new lemma is presented to obtain the deviation bounds of the membership functions in the sampled-data fuzzy control system and to establish a quantitative relation between the deviation bounds and the upper bound of time-varying sampling intervals. Then, a membership function deviation approach is proposed to de-sign the sampled-data fuzzy controller, and the membership-function-deviation-dependent condition for the existence of the sampled-data fuzzy controller is derived in terms of 1MIs. It is shown theoretical and numerically that the proposed membership function deviation approach can reduce the conservativeness of some existing results in the field of sampled-data fuzzy control design.(3) The design of static output feedback H∞ control is investigated for a class of non-linear NCSs which can be described by continuous-time T-S fuzzy models. The bilateral network channels with network-induced delays and data-packet dropouts are considered. First, a novel lemma about the deviations of membership functions which are dependent on the system output in the NCSs is established in network environment, which formulates a quantitative relation between the deviation bounds and the maximum allowable equivalent delay bound of the NCSs. Secondly, a membership-function-deviation-dependent condi-tion with a equality constraint is presented to design the static output fuzzy controller, and is transformed as an optimal problem for control design by using cone complementary linearization algorithm, which is easy to solved. In addition, by using relax lemma to decouple the Lyapunov matrices and system matrices, two new design methods of static output feedback fuzzy controllers are proposed in terms of quasi LMIs, where the one is shape-dependent design method and the other is shape-independent one. Finally, the rela-tion between the two design methods is established by comparing their feasible problems.(4) The design of event-triggered H∞ control is investigated for a class of nonlinear NCSs which can be described by continuous-time T-S fuzzy models. A new event-triggered transmission scheme is first proposed to reduce the network bandwidth utilization by reducing the amount of transmitting sampled-data. Under this scheme, the nonlinear NCS is formulated as a threshold-error-dependent T-S fuzzy system with asynchronous membership functions. Then, some co-design methods of the event-triggered transmission scheme and the fuzzy controller are derived by using the deviation bounds of asynchronous membership functions which are dependent on system state in network environment. It is shown that the proposed design method can reduce the conservativeness of some existing results.(5) The design of event-triggered H∞ filtering is investigated for a class of nonlinear networked systems which can be described by continuous-time T-S fuzzy models. The sys-tem output is sampled with time-varying sampling periods. Firstly, a new event-triggered transmission scheme on time-varying sampled outputs is proposed to reduce the amount of transmitting sampled-data. Notice that only the part of the hysteretic sampled-data are received to regulate the filter by a ZOH. To fire the fuzzy filter and to estimate system information in real time, a new synchronous fuzzy filter with the membership functions on filter state and the sampled-state of the filter is proposed, such that the clock in the filter and the one in nonlinear system are synchronous. Considering the fuzzy filter and the event-triggered transmission scheme, the networked fuzzy filter error system with the asyn-chronous membership functions is modeled as a threshold-error-dependent norm bounded uncertain T-S fuzzy system. Third, a co-design method of the event-triggered transmission scheme and the fuzzy filter is presented, and a membership-function-deviation-dependent condition for the existence of the parameters of the event-triggered transmission scheme and the gain matrices of the fuzzy filter is derived.
Keywords/Search Tags:Networked Control Systems, Networked Filtering Systems, Sampled-Data Control Systems, Takagi-Sugeno Fuzzy Model, Membership function deviation, Event- triggered transmission scheme, Fuzzy Control/Filtering, H_∞ Control/Filtering, Tracking control
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