Showing papers by "Cristina I. Muresan published in 2017"

Comparative evaluation of a novel principle for PID autotuning

Abstract: PID controllers are still the most widely used controllers in industrial applications However, industrial reports indicate that 60% of loops are poorly tuned and 25% never fulfill the specifications Operator training may be not available for re-tuning the loops, or the number of loops may be too large Despite this, a significant operation time is still based on manually tuned controllers Hence, efforts to develop autotuning PID methods are still very much justified In this paper, a novel principle for such autotuning technique is extensively evaluated on typical benchmark processes; comparison to several popular autotuning methods shows its superiority

Discrete-time implementation and experimental validation of a fractional order PD controller for vibration suppression in airplane wings

Abstract: Vibrations in airplane wings have a negative impact on the quality and safety of a flight. For this reason, active vibration suppression techniques are of extreme importance. In this paper, a smart beam is used as a simulator for the airplane wings and a fractional order PD controller is designed for active vibration mitigation. To implement the ideal fractional order controller on the smart beam unit, its digital approximation is required. In this paper, a new continuous-to-discrete-time operator is used to obtain the discrete-time approximation of the ideal fractional order PD controller. The efficiency and flexibility, as well as some guidelines for using this new operator, are given. The numerical examples show that high accuracy of approximation is obtained and that the proposed method can be considered as a suitable solution for obtaining the digital approximation of fractional order controllers. The experimental results demonstrate that the designed controller can significantly improve the vibration suppression in smart beams.

Fractional Calculus Applications in Modeling and Design of Control Systems

Abstract: Fractional calculus represents the generalization of integration and differentiation to an arbitrary order. Since the very first occurrence of fractional differentiation more than 300 years ago, fractional calculus and research related to its possible application have deserved ever-growing attention and interest. The research community has managed to bring forward ideas and concepts that justify the importance of fractional calculus for future engineering and science discoveries. What has begun as a means to describe abnormal behaviours in viscoelasticity or diffusion, power law phenomena, long range processes or fractal structures has spread to almost all engineering fields and applied sciences. Nowadays, its use in control engineering has been gaining more and more popularity in both modeling and identification, as well as in the controller tuning.

An experimental nanomedical platform for controller validation on targeted drug delivery

Abstract: Targeted drug delivery is a focus point in recent advances in the nanomedical field due to its many advantages such as decreased side effects, faster action and better drug absorption with less substance used. The paper presents an experimental platform that simulates the circulatory system: the passing of blood from arteries to smaller blood vessels, while also capturing the non-Newtonian characteristic of the blood. The targeted drug delivery is ensured by a scalable submersible equipped with various sensors and actuators such that the real-time position of the submersible can be determined and controlled in the circulatory system. The purpose of the presented work is to provide a solid foundation for experimental modeling of the interaction between the submersible and non-Newtonian fluids and for validating different control strategies suitable for velocity control. The experimental setup takes into account the real life difficulties of targeted drug delivery.

An optimal fractional order controller for vibration attenuation

Abstract: Unwanted vibrations may cause severe damage and may endanger the lives of passengers on board of an airplane. In the last years, there has been an increased focus on the study of active vibration techniques. A viable possibility to actively control the vibration of an airplane wing is by using piezoelectric actuators. The paper presents a novel tuning procedure of a fractional order Proportional Derivative controller based on three points of the magnitude Bode diagram. The eloquence of the controller is experimentally validated on an experimental setup consisting of an aluminum beam that replicates an airplane wing.

Fractional order modeling and control of a smart beam

Abstract: Smart beams are one of the most frequently used means of studying vibrations in airplane wings. Their mathematical models have been so far solely based on classical approaches that ultimately involve integer order transfer functions. In this paper, a different approach towards modeling such smart beams is considered, an approach that is based on fractional calculus. In this way, a fractional order model of the smart beam is obtained, which is able to better capture the dynamics of the system. Based on this novel fractional order model, a fractional order PDμ controller is then tuned according to a set of three design constraints. This design leads to a closed loop system that exhibits a much smaller resonant peak compared to the uncompensated smart beam system. Experimental results are provided, considering both passive and active control responses of the smart beam, showing that a significant improvement of the closed loop behavior is obtained using the designed controller.

Design and dynamics analysis of a fractional order IMC controller for a waste water treatment plant

Abstract: The advantages of using fractional calculus in designing control algorithms has been long discussed and demonstrated. In this paper, the theory of fractional calculus is used in combination with the Internal Model Control methodology to offer an alternative control solution for the concentration of biodegradable organic matter in the aeration tank of a waste water treatment facility. In contrast to the integer order Internal Model Controller, the fractional order controller has two tuning parameters, which allow for an increased flexibility in the tuning procedure. The fractional order Internal Model Controller is designed based on a simplified model of the process that occurs in the aeration tank. The dynamics of this controller is then analyzed using the nonlinear model of the process. Simulation results are provided including set point tracking, disturbance rejection and overall robustness.

Smart beam system: Identification and minimal realization using digraphs theory

Abstract: For modelling the dynamics and study of the active vibration suppression possibilities in aircraft wings, the smart beam is widely used. The advantages obtained through this approach are numerous. One of them are: aircraft stability and manoeuvrability, turbulence immunity, passenger safety and reduced fatigue damage. In this paper, the identification process has been presented, in the first step. As a result the transfer function of the continuous-time linear system was given. Then, for the obtained function the forms of minimal realizations were determined. The realization was obtained using the method based on one-dimensional digraph theory.