George Tecuceanu

From robust control to antiwindup compensation of electrohydraulic servo actuators

A method of designing the controller to solve the robust servomechanism problem is applied in the case of an electrohydraulic servo actuating primary flight control. This method is based on the well‐known solution consisting of two separate devices: a servocompensator, in fact an internal model of the exogenous dynamics, including the reference commands and disturbance signals; and a stabilizing compensator. The proof is made involving the servocompensator structure which is close to the one designed for step signals. The stabilizing compensator is assured by way of a linear quadratic optimal procedure. An antiwindup compensation is added to deal with the adverse effects caused by actuator saturation.

Intelligent control of HVAC systems. Part II: perceptron performance analysis

This is the second part of a paper on intelligent type control of Heating, Ventilating, and Air-Conditioning (HVAC) systems. The whole study proposes a unified approach in the design of intelligent control for such systems, to ensure high energy efficiency and air quality improving. In the first part of the study it is considered as benchmark system a single thermal space HVAC system, for which it is assigned a mathematical model of the controlled system and a mathematical model (algorithm) of intelligent control synthesis. The conception of the intelligent control is of switching type, between a simple neural network, a perceptron, which aims to decrease (optimize) a cost index, and a fuzzy logic component, having supervisory antisaturating role for neuro-control. Based on numerical simulations, this Part II focuses on the analysis of system operation in the presence only of the neural control component. Working of the entire neuro-fuzzy system will be reported in a third part of the study.

Simultaneous active vibration control and health monitoring of structures. Experimental results

The paper reports some results of a research project having as object the development of a structural health monitoring strategy in which the monitoring process is doubled by an active vibration control process, hereby resulting a longer operation time of the structure. Hardware and controller issues of impedance-based structural health monitoring and active control, both based on piezoelectric sensors-actuators, are summarized.

Control of uncertain systems by feedback linearization with neural networks augmentation. Part I. Controller design

The paper highlights the main steps of adaptive output feedback control for non-affine uncertain systems – both in parameters and dynamics – having a known relative degree. Given a reference model, the objective is to design a controller that forces the measured system output to track the reference model output with bounded errors. A single hidden layer neural network is used to counteract feedback linearization error. A dynamic observer of tracking error is added. The treatment of control saturation is also sketched. The mathematical model for the longitudinal dynamics of an experimental helicopter is used as framework.

Neuro-fuzzy control synthesis for hydrostatic type servoactuators. Experimental results

Continuing recent works of the authors, the paper shows the developing and the application of a neuro-fuzzy control law to the positioning outer loop of a hydrostatic type servoactuator. Experimental results are presented concerning dynamical behavior of the system by using this “intelligent” controller. Finally, arguments about the advantages of the new designed controller are summarized.

Inertially stabilized pointing control system

A pointing control system, combining passive inertial stabilization with active control, is presented. Such systems can direct an apparatus towards a fixed or slow moving target from a moving vehicle whose motion is almost rectilinear. The system was initially conceived to study the total solar eclipse in August 1999 in Romania. The passive inertial stabilization method consists of suspending a large mass by means of very low friction bearings. Consequently, a good static and dynamic equilibration is required. If the position information used by the control system is obtained by processing the image of the target, the large time delay involved makes the control synthesis rather difficult. In this paper, two control synthesis approaches, both providing the required tracking precision, and a comparison between the two corresponding control algorithms are presented.