Adolfo Bauchspiess

Fuzzy Inference System Applied to Edge Detection in Digital Images

First-order linear filters constitute the algorithms most widely applied to edge detection in digital images. Nevertheless they don’t allow good results to be obtained from images where the contrast varies a lot, due to non-uniform lighting, as it happens during acquisition of most part of natural images. In this paper, we evaluate the performance of a fuzzy inference system in edge detection. The results for images with high contrast variation are compared to those obtained with the linear Sobel operator.

New delay-and-delay-derivative-dependent stability criteria for systems with time-varying delay

This paper provides new delay-and-delay-derivative-dependent criteria for systems with the delay and its derivative varying within intervals. With introduction of new Lyapunov-Krasovskii functionals, a less conservative upper bound for the maximum delay is achieved. Examples show that the resulting criteria outperform previously published results in the literature.

Robust stability of networked control systems

In this paper, a robust stability criterion is proposed for NCSs liable to model uncertainties and time-varying delays. The analysis concerns the establishment of a maximum allowable delay bound for continous time NCSs under parameter uncertainties. The new proposed criterion is based on the solution of a set of Linear Matrix Inequalities (LMIs). Numerical examples are given to validate the theoretical result.

Delay-Dependent Robust H∞ Output Tracking Control for Uncertain Networked Control Systems

Abstract In this paper, the H ∞ output tracking problem for networked control systems (NCSs) liable to model uncertainties and with delays varying within intervals is investigated. A new method is proposed to the robust H ∞ output tracking analysis and control design for NCSs. The results presented here are an improvement over previous ones, for the analysis incorporates state-of-the-art stability techniques for systems with time-varying delays such as convex optimization technique, piecewise analysis method, and a new delay fractioning approach with the introduction of a novel auxiliary delayed state. The analysis is enriched with a numerical example that illustrates the advantages of our criteria which outperform previous criteria in the literature. Moreover, an illustrative example shows the effectiveness of the proposed H ∞ output tracking control design.

Robust stability criteria for uncertain systems with delay and its derivative varying within intervals

In this paper, stability criteria are proposed for linear systems liable to model uncertainties and with the delay and its derivative varying within intervals. The results are an improvement over previous ones due to the development of a new Lyapunov-Krasovskii functional (LKF). The analysis incorporates recent advances such as convex optimization technique and piecewise analysis method with new delay-interval depedent LKFs terms and a novel auxiliary delayed state. Stability conditions are provided for the cases when the delay derivative is upper and lower bounded, when the lower bound is unknown, and when no restrictions are cast upon the derivative. The analysis is enriched with numerical examples that illustrate the effectiveness of our criteria which outperform previous criteria in the literature for nominal and uncertain delayed systems.

Fuzzy Thermal Control with Remote Access for Building Automation

Abstract This paper presents the development of a project that aims thermal efficiency in building automation. The intemet infrastructure is used to develop a computational system for remote supervision. As building automation involves time-varying, distributed parameter systems we propose the use of fuzzy logic to implement an expert rule based systems that take care of the different contexts of the building management. The implementation of a prototype has been carried out on PIC16F877 microcontrollers.

Remote experimentation on a three coupled water reservoirs

A remote laboratory for long-distance education is presented: the level control of three coupled water reservoirs. This process is non-linear and multivariable so that different control problems and strategies can be shown. The user can control and visualize the experiment in real-time using a standard Web browser; no additional software is required. PID, state-space, fuzzy and exact linearization have been implemented on this process. Multivariable PID with the most common references are already available for remote experimentation.

Dynamic Timed Energy Efficient and Data Collision Free MAC Protocol for Wireless Sensor Networks

This article proposes a new data collision free medium access control protocol for wireless sensor networks in automation environments based on time division multiple access (TDMA) with duty cycling, which presents less energy consumption than the S-MAC protocol while maintain high data throughput. The new protocol employs single channel and a carrier sense approach. Simulation results are presented and show how the new proposal outperforms the S-MAC protocol.

Control design in a distributed WNCS using energy optimal scheduled medium access

In Wireless Networked Control Systems (WNCS) with more than one concurrent control loop accessing the network, we need a control design that incorporates effects from the communication protocol (delays, packet dropouts, jitter) as well as energy and computation restrictions of the network nodes (e.g. bandwidth, node energy, transmission power). In practice, increasing communication frequency leads to a decreasing network lifetime and vice versa. In literature this joint design approach is referred to as control-communication or control-scheduling co-design. In this work, we present a new approach for the synthesis of robust or gain-scheduled controllers in a distributed WNCS, depending only on the sampling period. We use a scheduling policy computed by an iterative optimization algorithm to maximize the network lifetime and guarantee Lyapunov stability of the selected feedback control law with bounded delay and sampling intervals.

Novel stabilization technique for the H ∞ control of systems with time-varying input delay

This paper addresses H∞ control strategies for time-delay systems with input delay and its derivative varying within intervals. With the development of a new Lyapunov-Krasovskii functional, we propose a new performance criterion which combines state-of-the-art stability techniques with an improved piecewise analysis method. For the H∞ control design, we state a new stabilization technique based on the use of the Simulated Annealing (SA) algorithm. We also derive traditional stabilization methods: the use of predefined scalars and a modified cone complementarity linearization algorithm, in order to compare their efficiency with the proposed control design technique. The advantages of our H∞ performance and control criteria are also highlighted with numerical examples, and an illustrative example shows the effectiveness of the new control design technique using SA algorithm.