On the Stability Analysis of Perturbed Continuous T-S Fuzzy Models

This paper deals with the stability problem of continuous-time Takagi-Sugeno (T-S) fuzzy models. Based on the Tanaka and Sugeno theorem, a new systematic method is introduced to investigate the asymptotic stability of T-S models in case of having second-order and symmetric state matrices. This stability criterion has the merit that selection of the common positive-definite matrix P is independent of the sub-diagonal entries of the state matrices. It means for a set of fuzzy models having the same main diagonal state matrices, it suffices to apply the method once. Furthermore, the method can be applied to T-S models having certain uncertainties. We obtain bounds for the uncertainties under which the asymptotic stability of the system is guaranteed. The obtained bounds are shown to be tight. Finally, the maximum permissible uncertainty bounds are investigated. Several examples are given to illustrate the effectiveness of the proposed method

Consensus in networks of uncertain robot manipulators without using neighbors’ velocity information

International audienceIn this paper, new distributed adaptive methods are proposed for solving both leaderless and leader–follower consensus problems in networks of uncertain robot manipulators, by estimating only the gravitational torque forces. Comparing with the existing adaptive methods, which require the estimation of the whole dynamics, presented methods reduce the excitation levels required for efficient parameter search, the convergence time, and the complexity of the regressor. Additionally, proposed schemes eliminate the need for velocity information exchange between the agents. Global asymptotic synchronization is shown by introducing new Lyapunov functions. Simulation results are provided for a network of 10 4-DOF robot manipulators

Event-triggered simultaneous fault detection and tracking control for multi-agent systems

The main aim of this study is to design distributed simultaneous fault detection and control units for multi-agent systems subject to limited communication and energy resources. For this purpose, each agent is equipped with a single module that generates both the residual signal for the fault detection task, as well as the control input of each agent for the tracking objective. To reduce the communication among the agents, an event-triggered data transmission paradigm is considered by using a dynamic triggering rule which results in higher data transmission reduction in comparison with the static triggering condition. Moreover, the proposed dynamic observer-based structure for the detector-controller module provides more degrees of freedom compared to the static Luenberger observer. The design parameters are obtained by solving a multi-objective optimisation problem considering the fault detection, tracking, and communication objectives. Simulation results illustrate the effectiveness and capabilities of the proposed method

Event-triggered simultaneous fault detection and consensus control for linear multi-agent systems

This paper investigates the design and development of event-triggered simultaneous fault detection and consensus control (SFDCC) problem for a network of linear agents. Each agent is equipped with a distributed SFDCC unit that uses the information from the relative measurement sensors and data transmission facilities. It is assumed that the data is transmitted from an agent to its neighbours whenever a specific event condition is satisfied. With the proposed methodology each agent can detect not only its own fault but also the faults occurred in its neighbors and at the same time, all the agents can track the output of a reference model. The parameters of the SFDCC module are designed such that a mixed H?/H- performance index is satisfied based on sufficient conditions in terms of extended linear matrix inequalities (LMIs). It is shown that by using event-triggered data transmission, the amount of data transmitted from an agent to its neighbors and the actuator updates are reduced. Simulation results are presented for fault detection and control of a group of unmanned underwater vehicles to demonstrate and verify the effectiveness of the proposed methodology.Scopu

Event-triggered fault detection and isolation for discrete-time linear systems

In this study, the problem of event-triggered fault detection and isolation (FDI) for discrete-time linear time invariant systems is considered. Using a Leunberger observer as the residual generator, a multi-objective formulation of the FDI problem is presented based on l1, H- and H? performance indices. For each performance index, sufficient conditions for the design of FDI observer are presented based on linear matrix inequalities (LMIs). To reduce the conservativeness of the multi-objective problem, extended LMIs are used to eliminate the couplings of Lyapunov matrices with the system state space matrices. It is shown that through an event-triggered data transmission mechanism, the amount of data that is sent to the FDI module is significantly decreased. Simulation results corresponding to a remotely operated vehicle demonstrate the effectiveness and capabilities of the proposed design methodology. The Institution of Engineering and Technology 2016.Scopu

Improvement of Performance Range of Centrifugal Compressors Gas by Surge Line Modification Using Active Controller Based on Fuzzy Logic

In this work, surge of prevention is a critical problem in oil and gas industries, particularly when return gas flow or gas flow reduces in transportation of gas pipelines. This paper is illustrated new results about surge control of centrifugal compressors .surge phenomenon is flow unsteady state in compressors which causes damages seriously in compressor construction. Furthermore, it also demonstrates in comparison with anti surge control ،active surge control expands stability range.Active surge control which based on fuzzy logic،is the main idea that used in this investigation. Using fuzzy controller causes an improvement in compressor's condition and increase performance range of the compressor, in addition to prevention of any instability in compressor. The simulation results is also satisfactory