On-line modeling and control via T-S fuzzy models for nonaffine nonlinear systems using a second type adaptive fuzzy approach

[[abstract]]This paper proposes a novel method for on-line modeling and robust adaptive control via Takagi-Sugeno (T-S) fuzzy models for nonaffine nonlinear systems, with external disturbances. The T-S fuzzy model is established to approximate the nonaffine nonlinear dynamic system in a linearized way. The so-called second type adaptive law is adopted, where not only the consequent part (the weighting factors) of fuzzy implications but also the antecedent part (the membership functions) of fuzzy implications are adjusted. Fuzzy B-spline membership functions (BMFs) are used for on-line tuning. Furthermore, the effect of all the unmodeled dynamics, BMF modeling errors and external disturbances on the tracking error is attenuated by a fuzzy error compensator which is also constructed from the T-S fuzzy model. In this paper, we can prove that the closed-loop system which is controlled by the proposed controller is stable and the tracking error will converge to zero. Three examples are simulated in order to confirm the effectiveness and applicability of the proposed methods in this paper.[[notice]]補正完

Development and Implementation of Some Controllers for Performance Enhancement and Effective Utilization of Induction Motor Drive

The technological development in the field of power electronics and DSP technology is rapidly changing the aspect of drive technology. Implementations of advanced control strategies like field oriented control, linearization control, etc. to AC drives with variable voltage, and variable frequency source is possible because of the advent of high modulating frequency PWM inverters. The modeling complexity in the drive system and the subsequent requirement for modern control algorithms are being easily taken care by high computational power, low-cost DSP controllers. The present work is directed to study, design, development, and implementation of various controllers and their comparative evaluations to identify the proper controller for high-performance induction motor (IM) drives. The dynamic modeling for decoupling control of IM is developed by making the flux and torque decoupled. The simulation is carried out in the stationary reference frame with linearized control based on state-space linearization technique. Further, comprehensive and systematic design procedures are derived to tune the PI controllers for both electrical and mechanical subsystems. However, the PI-controller performance is not satisfactory under various disturbances and system uncertainties. Also, precise mathematical model, gain values, and continuous tuning are required for the controller design to obtain high performance. Thus, to overcome these drawbacks, an adapted control strategy based on Adaptive Neuro-Fuzzy Inference System (ANFIS) based controller is developed and implemented in real-time to validate different control strategies. The superiority of the proposed controller is analyzed and is contrasted with the conventional PI controller-based linearized IM drive. The simplified neuro-fuzzy control (NFC) integrates the concept of fuzzy logic and neural network structure like conventional NFC, but it has the advantages of simplicity and improved computational efficiency over conventional NFC as the single input introduced here is an error instead of two inputs error and change in error as in conventional NFC. This structure makes the proposed NFC robust and simple as compared to conventional NFC and thus, can be easily applied to real-time industrial applications. The proposed system incorporated with different control methods is also validated with extensive experimental results using DSP2812. The effectiveness of the proposed method using feedback linearization of IM drive is investigated in simulation as well as in experiment with different working modes. It is evident from the comparative results that the system performance is not deteriorated using proposed simplified NFC as compared to the conventional NFC, rather it shows superior performance over PI-controller-based drive. A hybrid fuel cell (FC) supply system to deliver the power demanded by the feedback linearization (FBL) based IM drive is designed and implemented. The modified simple hybrid neuro-fuzzy sliding-mode control (NFSMC) incorporated with the intuitive FBL substantially reduces torque chattering and improves speed response, giving optimal drive performance under system uncertainties and disturbances. This novel technique also has the benefit of reduced computational burden over conventional NFSMC and thus, suitable for real-time industrial applications. The parameters of the modified NFC is tuned by an adaptive mechanism based on sliding-mode control (SMC). A FC stack with a dc/dc boost converter is considered here as a separate external source during interruption of main supply for maintaining the supply to the motor drive control through the inverter, thereby reducing the burden and average rating of the inverter. A rechargeable battery used as an energy storage supplements the FC during different operating conditions of the drive system. The effectiveness of the proposed method using FC-based linearized IM drive is investigated in simulation, and the efficacy of the proposed controller is validated in real-time. It is evident from the results that the system provides optimal dynamic performance in terms of ripples, overshoot, and settling time responses and is robust in terms of parameters variation and external load

Identificacion y control de sistemas estocasticos con observaciones incompletas mediante modelos neurodifusos

En la práctica, los sistemas físicos obedecen a una dinámica multivariada e interactuante, que fácilmente es influenciada, perturbada o integrada por incertidumbres de diversas clases, las cuales inducen naturaleza estocástica al proceso global y algunas veces llegan a afectar la completitud de los datos. En esta tesis se presenta una metodología para la identificación y control de sistemas estocásticos con observaciones incompletas mediante modelos neuro-difusos. En particular, se desarrolla el análisis de la dinámica de un vehículo operado remotamente (ROV, Remotely Operated Vehicle) para aplicaciones submarinas, con el fin de determinar el modelo matemático y obtener simulaciones de la respuesta natural del sistema. Adicionalmente, se emplea un mecanismo de identificación del proceso mediante un modelo neuronal y otro neuro-difuso, los cuales se integran con un esquema de reducción de perturbaciones estocásticas para sobreponer las observaciones incompletas que residan en el proceso operativo. Finalmente, se propone un modelo neuro-difuso (ANFIS, Adaptive neuro fuzzy inference system) para controlar el sistema y se compara con el desempeño de una red neuronal con múltiples elementos Adaline (MADALINE, Multiple Adaline) con el fin de analizar las ventajas que ofrece la inclusión de conocimiento mediante reglas de inferencia difusa. Los resultados experimentales mostraron que se logró la controlabilidad del sistema llevándolo a un estado globalmente atractivo en el sentido de Lyapunov. Se pudo concluir que gracias a la capacidad de adaptación y contenencia de conocimiento lingüístico de los modelos neuro-difusos, el desempeño de control tuvo mayor rendimiento en términos de precisión y robustez, al compararlo con el modelo neuronal en aplicaciones operativas del ROV. Se destaca además la facilidad que tienen los modelos neuro-difusos para ser ampliamente potenciados mediante la integración de otros esquemas de procesamiento, dados los asuntos que quedaron pendientes en relación al error de estado estable y las perturbaciones ocasionadas por la interacción de los componentes.Magister en Automatización y Contro

Robust adaptive fuzzy-neural controllers for uncertain nonlinear systems

[[abstract]]A robust adaptive fuzzy-neural controller for a class of unknown nonlinear dynamic systems with external disturbances is proposed. The fuzzy-neural approximator is established to approximate an unknown nonlinear dynamic system in a linearized way. The fuzzy B-spline membership function (BMF) which possesses a fixed number of control points is developed for online tuning. The concept of tuning the adjustable vectors, which include membership functions and weighting factors, is described to derive the update laws of the robust adaptive fuzzy-neural controller. Furthermore, the effect of all the unmodeled dynamics, BMF modeling errors and external disturbances on the tracking error is attenuated by the error compensator which is also constructed by fuzzy-neural inference. We prove that the closed-loop system which is controlled by the robust adaptive fuzzy-neural controller is stable and the tracking error will converge to zero under mild assumptions. Several examples are simulated in order to confirm the effectiveness and applicability of the proposed methods