A generalised integral polynomial Lyapunov function for nonlinear systems

[EN] This work generalises the line-integral Lyapunov function in (Rhee and Won, 2006) for stability analysis of continuous-time nonlinear models expressed as fuzzy systems. The referred result applied only to Takagi¿Sugeno representations, and required memberships to be a tensor-product of functions of a single state; these are generalised here so that membership arguments can be arbitrary polynomials of the state variables; in this way, systems for which earlier results cannot be applied are now covered. Both the modelling and the integral terms appearing in the Lyapunov functions are generalised to a fuzzy polynomial case. Illustrative examples show the advantage of the proposed method against previous literature, even in the TS case.The authors gratefully to the financial support of Spanish ministry of Economy and European Union, grant DPI2016-81002-R (AEI/FEDER, UE), the CONACyT/COECyT Sonora scholarship 383252, and Project ITSON-PROFAPI-CA 2017-0088.Gonzalez-German, IT.; Sala, A.; Bernal Reza, MÁ. (2019). A generalised integral polynomial Lyapunov function for nonlinear systems. Fuzzy Sets and Systems. 356:77-91. https://doi.org/10.1016/j.fss.2018.02.005S779135

Adaptive Robust Control of Biomass Fuel Co-Combustion Process

The share of biomass in energy production is constantly growing. This is caused by environmental and industry standards and EU guidelines. Biomass is used in the process of co-firing in large power plants and industrial installations. In the existing power stations, biomass is milled and burned simultaneously with coal. However, low-emission combustion techniques, including biomass co-combustion, have some negative side effects that can be split into two categories. The direct effects influence the process control stability, whereas the indirect ones on combustion installations via increased corrosion or boiler slagging. The effects can be minimised using additional information about the process. The proper combustion diagnosis as well as an appropriate, robust control system ought to be applied. The chapter is devoted to the analysis of modern, robust control techniques for complex power engineering applications

非線形システムに対する制御系設計と外乱抑制のための積分型リアプノフ関数アプローチ

電気通信大学202

Performance Guarantee of a Class of Continuous LPV System with Restricted-Model-Based Control

This paper considers the problem of the robust stabilisation of a class of continuous Linear Parameter Varying (LPV) systems under specifications. In order to guarantee the stabilisation of the plant with very large parameter uncertainties or variations, an output derivative estimation controller is considered. The design of such controller that guarantee desired  induced gain performance is examined. Furthermore, a simple procedure for achieving the  norm performance is proved for any all-poles single-input/single-output second order plant. The proof of stability is based on the polytopic representation of the closed loop under Lyapunov conditions and system transformations. Finally, the effectiveness of the proposed method is verified via a numerical example

Stabilization and local stability analysis of continuous-time nonlinear systems represented by Takagi-Sugeno fuzzy models

Orientadores: Pedro Luis Dias Peres, Ricardo Coração de Leão Fontoura de OliveiraDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de ComputaçãoResumo: Esta dissertação aborda os problemas de análise de estabilidade local, estimativa de região de atração e estabilização local por realimentação de estados para sistemas não lineares contínuos no tempo representados por modelos nebulosos Takagi-Sugeno (T¿S). Para certificar a estabilidade local e projetar o controlador, condições suficientes, expressas em termos de desigualdade matriciais lineares (do inglês, Linear Matrix Inequalities ¿ LMIs) dependentes de parâmetros são fornecidas, tendo como base matrizes de Lyapunov e variáveis de folga polinomiais homogêneas de grau arbitrário. Utilizando-se uma representação politópica para a derivada das funções de pertinência do modelo T¿S, evita-se a necessidade do estabelecimento de limitantes para a taxa de variação. Como contribuição adicional, propõe-se que termos não lineares da matriz Jacobiana associada ao modelo T¿S sejam substituídos, sempre que possível, pela correspondente série de Taylor truncada em uma ordem pré-determinada, evitando a definição de um novo conjunto de parâmetros incertos, o que aumentaria a complexidade da representação. Exemplos emprestados da literatura T¿S são utilizados para ilustrar que os métodos propostos fornecem melhores resultados que outras abordagens, em termos de maiores estimativas para as regiões de atração, tanto no caso de análise de estabilidade, quanto na síntese de controle estabilizante por realimentação de estados.Nesta dissertação também foi feito um estudo sobre o uso de programação linear, como alternativa aos resolvedores especializados em LMIs, para a análise de estabilidade de sistemas lineares incertosAbstract: This dissertation addresses the problems of local stability analysis, estimation of domains of attraction, and local state-feedback stabilization for continuous time nonlinear systems represented by Takagi-Sugeno (T¿S) fuzzy models. Sufficient conditions, expressed in terms of parameter-dependent Linear Matrix Inequalities (LMIs), are given to certify the local stability and for control design, based on homogenous polynomial Lyapunov matrices and slack variables of arbitrary degree. By using a polytopic representation for the time-derivative of the membership functions of the T-S model, upper bounds for the variation rates are not required. As an additional contribution, nonlinear terms of the Jacobian matrix associated with the T¿S model are replaced, whenever possible, by the corresponding Taylor series, truncated at a predetermined order, avoiding the definition of a new set of uncertain parameters, which would increase the complexity of the representation. Examples borrowed from the T¿S literature are used to illustrate that the proposed methods provide better results than other approaches in terms of larger estimates for the regions of attraction, both in the case of stability analysis and in the synthesis of state-feedback stabilizing controllers. A study about the use of linear programming, as an alternative to specialized LMI solvers, for stability analysis of uncertain linear systems is also included in the dissertationMestradoAutomaçãoMestra em Engenharia Elétrica132807/2018-12017/18785-5CNPQFAPES

Proposed Fuzzy Real-Time HaPticS Protocol Carrying Haptic Data and Multisensory Streams

Sensory and haptic data transfers to critical real-time applications over the Internet require better than best effort transport, strict timely and reliable ordered deliveries. Multi-sensory applications usually include video and audio streams with real-time control and sensory data, which aggravate and compress within real-time flows. Such real-time are vulnerable to synchronization to synchronization problems, if combined with poor Internet links. Apart from the use of differentiated QoS and MPLS services, several haptic transport protocols have been proposed to confront such issues, focusing on minimizing flows rate disruption while maintaining a steady transmission rate at the sender. Nevertheless, these protocols fail to cope with network variations and queuing delays posed by the Internet routers. This paper proposes a new haptic protocol that tries to alleviate such inadequacies using three different metrics: mean frame delay, jitter and frame loss calculated at the receiver end and propagated to the sender. In order to dynamically adjust flow rate in a fuzzy controlled manners, the proposed protocol includes a fuzzy controller to its protocol structure. The proposed FRTPS protocol (Fuzzy Real-Time haPticS protocol), utilizes crisp inputs into a fuzzification process followed by fuzzy control rules in order to calculate a crisp level output service class, denoted as Service Rate Level (SRL). The experimental results of FRTPS over RTP show that FRTPS outperforms RTP in cases of congestion incidents, out of order deliveries and goodput

Performance improvement of professional printing systems : from theory to practice

Performance Improvement of Professional Printing Systems: from theory to practice Markets demand continuously for higher quality, higher speed, and more energy-efficient professional printers. In this thesis, control strategies have been developed to improve the performance of both professional inkjet and laser printers. Drop-on-Demand (DoD) inkjet printing is considered as one of the most promising printing technologies. It offers several advantages including high speed, quiet operation, and compatibility with a variety of printing media. Nowadays, it has been used as low-cost and efficient manufacturing technology in a wide variety of markets. Although the performance requirements, which are imposed by the current applications, are tight, the future performance requirements are expected to be even more challenging. Several requirements are related to the jetted drop properties, namely, drop velocity, drop volume, drop velocity consistency, productivity, and reliability. Meeting the performance requirements is restricted by several operational issues that are associated with the design and operation of inkjet printheads. Major issues that are usually encountered are residual vibrations in and crosstalk among ink channels. This results in a poor printing quality for high-speed printing. Given any arbitrary bitmap, the main objective is to design actuation pulses such that variations in the velocity and volume of the jetted drops are minimized. Several model-based feedfoward control techniques using an existing model are implemented to generate appropriate input pulses for the printhead. Although the implementation of the model-based techniques shows a considerable improvement of the printhead performance compared with the current performance, further improvements are still necessary. We observe that besides the pulse shape the state of the ink surface at the nozzle plate (speed, position) at the start of the pulse influences the drop velocity considerably. This state at firing depends also on previous pixels in the bitmap of the image. Consequently, any pulse design has to guarantee almost the same initial state when firing a drop. Based on these facts, a model-free optimization scheme is developed to minimize the drop velocity variations taking into account the bitmap information. Experimental results show the effectiveness of the optimized pulses. Laser printing systems are highly depending on the appropriate combination of several design factors so as to become functional in a desired working range. The physical printing process involves multiple temperature set points at different places, precise electro-magnetic conditions, transfer of toner through certain pressures and layouts, and many other technical considerations. In the laser printing system there are several challenging issues and unknown disturbances. They originate from different sources, such as the printer itself (unknown phenomena appear, disturbances that are not foreseen, wear, contamination, failures, bugs), the environment of the system (power supply variations, temperature, humidity, vibrations), and the printing media (weight, coating, thermal properties, humidity characteristics, and initial temperature). These issues have a negative effect on the stability and performance of the laser printing system. The objective is to design a control scheme to achieve printing quality requirements and a high productivity. Good printing quality means that the fusing temperature should track a certain reference signal at different operating conditions. Based on the printing system behavior, we propose two different control schemes to cope with the large parameter variations and disturbances, namely, a Model Reference Adaptive Controller (MRAC) and a nonlinear (scheduled) observer-based output feedback control scheme. Both control techniques yield considerable performance improvements compared with the present industrial controller