José Rodellar

Adaptive control of a hysteretic structural system

This paper addresses the problem of controlling a second-order uncertain structural hysteretic system. The hysteretic behavior is represented by a Bouc-Wen model whose parameters lie within intervals. It is shown that the nonlinear response of the model acts as a bounded disturbance. This fact is used to elaborate an adaptive controller, to prove the closed-loop stability and to obtain performance bounds.

Dynamic properties of the hysteretic Bouc-Wen model ☆

Abstract The Bouc-Wen model, widely used in structural and mechanical engineering, gives an analytical description of a smooth hysteretic behavior. In practice, the Bouc-Wen model is mostly used within the following black-box approach: given a set of experimental input–output data, how to adjust the Bouc-Wen model parameters so that the output of the model matches the experimental data. It may happen that a Bouc-Wen model presents a good matching with the experimental real data for a specific input, but does not necessarily keep significant physical properties which are inherent to the real data, independently of the exciting input. This paper presents a characterization of the different classes of Bouc-Wen models in terms of their bounded input-bounded output stability property, and their capability for reproducing physical properties inherent to the true system they are to model.

Predictive control method for decentralized operation of irrigation canals

Abstract This paper presents a digital control scheme for water level regulation in irrigation canals. The scheme considers a prototype canal composed by a series of pools connected with active gates. A control system is designed for each pool to manipulate the upstream gate to satisfy the downstream level setpoints. Each control system is composed by two controllers: one implements a discrete time predictive control law that gives the desired discharge through the gate to ensure the downstream desired level; another one is a local control driving the gate to achieve the desired discharge. The paper presents the formulation of the global control scheme and shows results from simulations to illustrate and discuss the performance in different operation scenarios.

Q-statistic and T2-statistic PCA-based measures for damage assessment in structures

This article explores the use of principal component analysis (PCA) and T2 and Q-statistic measures to detect and distinguish damages in structures. For this study, two structures are used for experimental assessment: a steel sheet and a turbine blade of an aircraft. The analysis has been performed in two ways: (i) by exciting the structure with low-frequency vibrations using a shaker and using several piezoelectric (PZT) sensors attached on the surface, and (ii) by exciting at high-frequency vibrations using a single PZT as actuator and several PZTs as sensors. A known vibration signal is applied and the dynamical responses are analyzed. A PCA model is built using data from the undamaged structure as a reference base line. The defects in the turbine blade are simulated by attaching a mass on the surface at different positions. Instead, a progressive crack is produced to the steel sheet. Data from sets of experiments for undamaged and damaged scenarios are projected into the PCA model. The first two projections, and the Q-statistic and T2-statistic indices are analyzed. Q-statistic indicates how well each sample conforms to the PCA model. It is a measure of the difference or residual between a sample and its projection into the principal components retained in the model. T2-statistic index is a measure of the variation of each sample within the PCA model. Results of each scenario are presented and discussed demonstrating the feasibility and potential of using this formulation in structural health monitoring.

Active and semi-active control of structures – theory and applications: A review of recent advances

It is internationally recognized that structural control was introduced in civil engineering through a pioneering article by Yao and through the implementations promoted by Kobori. The concepts of active and semi-active structural control in civil and infrastructure engineering date back 40 years and much progress has been recorded during these four decades. Periodically, state-of-the-art manuscripts have been published and technical books were also printed to testify the maturation of the topic. This article only covers the period from the second semester of 2009 to the first semester of 2011, emphasizing the developments in terms of theoretical, numerical and experimental studies, as well as the use of control algorithms and devices in actual implementations. It is observed that there are still several operational limitations to prevent from the expected growth of the applications in standard design. Nevertheless, some innovative concepts help to foresee future developments within special sectors of applications.

ROBUST STABILIZATION OF A CLASS OF UNCERTAIN TIME DELAY SYSTEMS IN SLIDING MODE

This paper addresses the problem of robust stabilization of a class of uncertain systems subject to internal (i.e., in the state) point delays, external (i.e., in the input) point delays and nonlinear disturbances by using sliding mode control. Methods for the design of sliding mode controllers based on state feedback, static output feedback and dynamic output feedback, respectively, are proposed. Sufficient conditions for the asymptotic stability and robustnesss of the closed–loop systems are given under a wide class of admissible nonlinear disturbances.

Output feedback sliding mode control of base isolated structures

Abstract The paper addresses the problem of designing stabilizing output feedback controllers for a class of nonlinear seismically excited base isolated structures with unknown parametrical uncertainties. Two types (non-adaptive and adaptive) of sliding mode controllers are presented. In both schemes, only the information on the displacements and velocities of the base and the first floor is used in the controller design. A numerical example is given to illustrate the effectiveness of the proposed strategy to a 10-storey frictional base isolated structure being subject to the El Centro earthquake.

A linear controller for hysteretic systems

This note deals with the problem of regulating the displacement and velocity of a mechanical system that includes a Bouc-Wen hysteresis model both of which have uncertain parameters. The dynamic part of the hysteresis is not accessible to measurement and acts as an uncertain dynamic. It is shown that the global boundedness of the control and closed loop signals along with asymptotic regulation can be assured using a simple PID controller.

Composite semiactive control of a class of seismically excited structures

Abstract The paper deals with the formulation of semiactive controllers for a class of nonlinear seismically excited base-isolated structures in order to reduce the absolute motion of the base and the inter-story drifts of the building structure. The advantage of the proposed control scheme is that semiactive control devices are only required at the base and the first floor to adjust on-line the damping and stiffness using their displacements and velocities as feedback information. The feedback control law is derived and analyzed via Lyapunov stability techniques. A numerical example is given to illustrate the effectiveness of the control scheme for a 10-story frictional base-isolated structure subject to seismic actions.

Structure of Expansion-Contraction Matrices in the Inclusion Principle for Dynamic Systems

This paper characterizes a general structure of complementary matrices involved in the input-state-output inclusion principle for linear time invariant dynamic systems. Aggregations and restrictions are adopted as two practically important classes within this scheme. Further, contractibility conditions for feedback controllers are presented, including the decentralized control design. The identified structure enables the formulation of conditions on the complementary matrices which can be useful for analysis and synthesis of control problems.