Gisela Pujol

Adaptive Backstepping Control of Hysteretic Base-Isolated Structures

The paper considers a hybrid seismic control system for building structures, which combines a class of passive nonlinear base isolator with an active control system. The objective of the active component is to keep the base displacement relative to the ground, the interstory drift and the absolute acceleration within appropriate ranges. The base isolator device exhibits a hysteretic nonlinear behavior which is described by the Bouc-Wen model. The adaptive backstepping approach is used for the control design in order to cope with the nonlinearity and the presence of uncertainties. The control problem is formulated with representations of the system dynamics using two alternative coordinate sets: absolute (with respect to an inertial frame) and relative to the ground. A comparison between the two strategies is presented by means of numerical simulations.

Reliable H∞ control of a class of uncertain interconnected systems: an LMI approach

The aim of this work is to study the reliable control design problem for parameter-dependent interconnected systems in the presence of actuator failures. Moreover, the control ensures H ∞ performance in front of L 2 perturbations. A more practical model of actuators or control channel failures than outage is adopted, considering partial achievement. The continuous H∞ control problem is solved via elementary manipulations on linear matrix inequalities and the resulting control systems are robustly stable against plant uncertainties and failures.

Robust H2 static output feedback to control an automotive throttle valve

The paper presents a control strategy for an automotive electronic throttle body, a device largely used into vehicles to increase the efficiency of the combustion engines. The synthesis of the proposed controller is based on a linear matrix inequality (LMI) formulation, which allows us to deal with uncertainties on the measurements of the position of the throttle valve. The LMI approach generates a suboptimal solution for the robust ℋ2 static output feedback control problem, and the corresponding suboptimal control gain was evaluated in practice to control the valve position of the throttle. The usefulness of the approach has been verified not only by numerical simulations but also by real experiments taken in a laboratory prototype.

Stability of Markov jump systems with quadratic terms and its application to RLC circuits

The paper presents results for the second moment stability of continuous-time Markov jump systems with quadratic terms, aiming for engineering applications. Quadratic terms stem from physical constraints in applications, as in electronic circuits based on resistor (R), inductor (L), and capacitor (C). In the paper, an RLC circuit supplied a load driven by jumps produced by a Markov chain—the RLC circuit used sensors that measured the quadratic of electrical currents and voltages. Our result was then used to design a stabilizing controller for the RLC circuit with measurements based on that quadratic terms. The experimental data confirm the usefulness of our approach.

The Art of Control Algorithms Design and Implementation

This paper discusses some issues which are relevant when addressing the design and the implementation of control algorithms for smart structures: (1) the model of the closed control loop; (2) the control strategy; (3) the control methodology; (4) the feedback information constraints; and (5) the digital implementation. A case study is used to illustrate some of these issues.

A new device laboratory: Experimental validation

Abstract A device laboratory was designed to create a commanded disturbance to the Furuta inverted pendulum. This pendulum was modified by adding a second inverted pendulum coupled to the main one by means of a semi-rigid spring. The induced motion on the second inverted pendulum causes displacement of the center of mass of the system, producing a kind of perturbation similar to that presented on mobile inverted pendulum transportation units. A linear matrix inequality (LMI) controller is designed from the unperturbed model (based on the main pendulum without the second inverted one) and implemented to our system. Then, experimentally, the behaviour of the whole closed-loop system and the controller performance was analysed. According to the laboratory test, the LMI controller is robust enough in front of perturbation induced on the second pendulum.

Optimal complementary matrices in systems with overlapping decomposition: A computational approach

The paper deals with linear quadratic (LQ) optimal control of linear time-invariant (LTI) systems which are decomposed into overlapped subsystems. A mathematical framework (inclusion principle) is available to formalize different structural properties and relations between the initial and the expanded systems, in which the so called complementary matrices play an important role. Up to now, only the structure and conditions on these matrices have been studied in the literature, but not the way to obtain their numerical values systematically. This paper presents a computational approach to select complementary matrices, which can be useful for a practical use of overlapping decompositions. The specific objective is to obtain the complementary matrices such that the quadratic performance for the expanded optimal control problem is minimum. An example is supplied to illustrate the use of the proposed algorithm

A boundary control technique to the string-tip-mass system based on a non-symmetric peak-detector model

This paper presents a vibration control design to the string-tip-mass system by using a non-symmetric peak-detector mechanism. Previously, this peak-detector system was used as an easy algorithm to mitigate vibration on a real flexible structure. Moreover, its mathematical representation is simple and it just has two parameters to tune. Following this former experience, we adequate this strategy to the vibration control of the string-tip-mass system. Finally, and according to our numerical experiments, our control performance is better than the boundary damper control here programmed for comparison proposes.

Experimental study of an active control for a faulty perturbed flexible structure

In this paper, a linear dynamic control is developed for a faulty flexible structure subject to external ground perturbation. This active controller is based on H∞ theory and is designed using linear matrix inequality (LMI) theory. Lyapunov theory is invoked to validate the control design. According to experiments, where a two levels flexible building with active mass damper and external perturbation is employed, show that this strategy improves controller performance when it is compared with a given controller. This design faces the nonlinear structural system too. 20th Mediterranean Conference on Control and Automation (MED12).

Adaptive control design of structural systems

An adaptive H∞ control for active mass damper systems subject to external perturbation is developed in this paper. This robust controller is composed by the sum of a linear term plus an adaptive component. The linear term is designed using linear matrix inequality (LMI) theory. Then, the adaptive term is added to improve controller performance in presence of external disturbance and system fault. Lyapunov theory is invoked to validate our control design. According with experiments, where a flexible two levels building with active mass damper under external perturbation is employed, they show that this adaptive term improves controller performance.