María Guinaldo

Distributed event-based control for interconnected linear systems

This paper presents a distributed event-based control strategy for a networked dynamical system consisting of N linear time-invariant interconnected subsystems. Each subsystem broadcasts its state over the network according to some triggering rules which depend on local information only. The system converges to an adjustable region around the equilibrium point under the proposed control design, and the existence of a lower bound for the broadcasting period is guaranteed. The effect of the coupling terms over the region of convergence and broadcasting period lower bound is analyzed, and a novel model-based approach is derived to reduce the communications. Simulation results show the effectiveness of the proposed approaches and illustrate the theoretical results.

Distributed event-triggered control with network delays and packet losses

This paper presents a distributed event-based control approach to cope with communication delays and packet losses affecting a networked dynamical system consisting of N linear time-invariant coupled systems. Two communication protocols are proposed to deal with these communication effects. It is shown that both protocols preserve the system stability in the sense that the state of every subsystem converges to a small region around the origin if the delay and the number of packet losses are bounded. Analytical expressions for the delay bound and the maximum number of consecutive packet losses are derived. Simulations illustrate the results.

The Ball and Beam System: A Case Study of Virtual and Remote Lab Enhancement With Moodle

Web-based labs are key tools for distance education that help to illustrate scientific phenomena, which require costly or difficult-to-assemble equipment. Easy Java Simulations (EJS) is an authoring tool that speeds up the creation of these kind of labs. An excellent proof of the EJS potential is the open source physics (OSP) repository, which hosts hundreds of free EJS labs. Learning management systems, such as Moodle, provide social contexts where students interact with each other. The work described in this paper looks for the synergy of both tools, EJS and Moodle, by supporting the deployment of EJS labs into Moodle and thus enriching them with social features (e.g., chat, forums, and videoconference). To test this approach, the authors have created the ball and beam lab, which helps students of automatic control engineering to train different advanced techniques (robust, fuzzy, and reset control), and compare their performance in relation to a conventional proportional-integral-derivative control.

Distributed event-triggered control for non-reliable networks

This paper presents a distributed event-based control approach to cope with communication delays and packet losses affecting a networked dynamical system. Two network protocols are proposed to deal with these communication effects. The stability of the system is analyzed for constant and time-dependent trigger functions, showing that asymptotic stability can be achieved with the latter design, and this also guarantees a lower bound for the inter-event times. Analytical expressions for the delay bound and the maximum number of consecutive packet losses are derived for different scenarios. Finally, the results are illustrated through a simulation example.

A Mobile Robots Experimental Environment with Event-Based Wireless Communication

An experimental platform to communicate between a set of mobile robots through a wireless network has been developed. The mobile robots get their position through a camera which performs as sensor. The video images are processed in a PC and a Waspmote card sends the corresponding position to each robot using the ZigBee standard. A distributed control algorithm based on event-triggered communications has been designed and implemented to bring the robots into the desired formation. Each robot communicates to its neighbors only at event times. Furthermore, a simulation tool has been developed to design and perform experiments with the system. An example of usage is presented.

Distributed control for large-scale systems with adaptive event-triggering

Abstract The asymptotic stability of distributed-event triggered control for large-scale interconnected systems can be achieved with time-dependent trigger functions. The choice of some of the parameters in the trigger functions relies on some properties of the overall system, which are not known a priori by the individual nodes. This paper presents an iterative method for the distributed estimation of such parameters, which allows the event-triggered control algorithm to evolve to a less conservative design. We provide proofs of convergence while the asymptotic stability and the existence of a lower bound for the inter-event times are preserved. The complexity of the proposed approach is analyzed, and the results are illustrated through simulations.

Platform for Teaching Mobile Robotics

This paper describes the development of a motivating and innovative multi-robot formation control platform for laboratory experiments with mobile robots. The platform is composed of two components: a simulator and an environment to experiment with low cost wheeled mobile robots. The environment constitutes a ready to use test tool that provides to engineering students the opportunity to simulate and test many different formation and cooperation control strategies with a real system. Currently the platform is used in the Systems and Control Engineering Master program offered by the National University of Distance Education (UNED) and the Complutense University of Madrid (UCM) in Spain. The use of the platform exposes students to hands-on laboratory sessions, contributing to their development as engineers.

Control of a Chain Pendulum: A fuzzy logic approach

AbstractIn this paper we present a real application of computational intelligence. Fuzzy control of a non-linear rotary chain pendulum is proposed and implemented on real prototypes. The final aim is to obtain a larger region of attraction for the stabilization of this complex system, that is, a more robust controller. As it is well-known, fuzzy logic exploits the tolerance for imprecision, uncertainty and partial truth to achieve tractability, robustness and low solution cost when dealing with complex systems. In this case, the control strategy is based on a Takagi-Sugeno fuzzy model of the strongly non-linear multivariable system. Simulation and experimental results on the real plant have been obtained and tested in a rotary inverted pendulum and in a double rotary inverted pendulum. They have been compared to other feedback control strategies such as Full State Feedback or Linear Quadratic Regulator with encouraging results. Fuzzy control allows to enlarge the stability region of control. Indeed, the r...

A novel approach for periodic event-triggering based on general quadratic functions

This paper is concerned with periodic event-triggered control, which avoids the continuous monitoring of the state of the system while reducing the number of control updates. A new form of quadratic event-triggering condition is proposed to enlarge the inter-event times. The asymptotic stability criteria is analyzed by means of Lyapunov-Krasovskii functionals and the stability condition is expressed in terms of linear matrix inequalities. Simulation and experimental results are given to show the effectiveness of the proposed method.

An Interactive Tool for Outdoor Computer Controlled Cultivation of Microalgae in a Tubular Photobioreactor System

This paper describes an interactive virtual laboratory for experimenting with an outdoor tubular photobioreactor (henceforth PBR for short). This virtual laboratory it makes possible to: (a) accurately reproduce the structure of a real plant (the PBR designed and built by the Department of Chemical Engineering of the University of Almería, Spain); (b) simulate a generic tubular PBR by changing the PBR geometry; (c) simulate the effects of changing different operating parameters such as the conditions of the culture (pH, biomass concentration, dissolved O2, inyected CO2, etc.); (d) simulate the PBR in its environmental context; it is possible to change the geographic location of the system or the solar irradiation profile; (e) apply different control strategies to adjust different variables such as the CO2 injection, culture circulation rate or culture temperature in order to maximize the biomass production; (f) simulate the harvesting. In this way, users can learn in an intuitive way how productivity is affected by any change in the design. It facilitates the learning of how to manipulate essential variables for microalgae growth to design an optimal PBR. The simulator has been developed with Easy Java Simulations, a freeware open-source tool developed in Java, specifically designed for the creation of interactive dynamic simulations.