Showing papers by "Isabela Roxana Birs published in 2016"

A comparison between integer and fractional order pdµ controllers for vibration suppression

Abstract: Along the years, unwanted vibrations in airplane wings have led to passenger discomfort. In this study, the airplane wing is modeled as a cantilever beam on which active vibration suppression is tested. The paper details the tuning of both integer and fractional order Proportional Derivative type controllers based on constraints imposed in the frequency domain. The controllers are experimentally validated and the results prove once more the superiority of the fractional order approach.

Vibration suppression with fractional-order PIλDμ controller

Abstract: Cantilever beams have an important role in day to day life in bridges, towers, buildings and aircraft wings, making active vibration suppression a highly researched field. The purpose of this paper is to detail the design of fractional order PID controllers for smart beams. A novel tuning procedure is proposed based on solving a set of nonlinear complex equations that directly aim at reducing the resonant peak. The control parameters are computed through optimization techniques, making sure that the best ones are chosen. The practical stand was realized using magnet-coil approach and not piezoelectric actuators. The experimentally obtained vibration results prove that fractional order PID controllers can be used in practice to significantly reduce the amplitude and settling time of the vibrating system.

Experimental results of a fractional order PD λ controller for vibration suppresion

Abstract: Vibration occurs in numerous important domains, such as the aerospace industry, and has negative effects since it can limit the life span of the devices, cause malfunctioning or even system instability. The necessity of research on vibration suppression in aeroplane wings is important from a scientific and technologic point of view: to provide better, more efficient, robust, cheaper solutions to eliminate vibrations effects, which triggers the socioeconomic aspect regarding the increase of flight safety and passenger comfort. Vibration suppression can be achieved using passive techniques, but they come along with certain disadvantages related to efficiency/costs. An alternative solution is to use active control. Several active control strategies have been proposed so far, with aeroplane wings/helicopter blades simulated as smart cantilever beams. The present paper proposes a fractional order Proportional Derivative controller, designed using frequency domain specifications. The case study consists in a smart beam equipped with dedicated sensors and actuators. The experimental results, considering both passive and active control responses of the smart beam, show that the proposed method leads to significant improvement of the closed loop behavior.

Seismic Mitigation in Civil Structures Using a Fractional Order PD Controller

Abstract: In this paper, a systematic tuning procedure for a fractional order PD controller for seismic mitigation is proposed. The tuning is based upon reducing the magnitude of the compensated system at the resonance frequency as compared to the magnitude of the uncompensated structure. For simplicity, a laboratory scale 1DOF (one degree of freedom) steel structure is used as the case study, The simulation results considering the El Centro earthquake accelerograms show that the designed control strategy is highly suitable for solving seismic mitigation of steel structures and ensures improved response in comparison with steel structures equipped with passive protection. 

Modelling and calibration of a conventional activated sludge wastewater treatment plant

Abstract: Wastewater treatment plants (WWTPs) are key infrastructures for ensuring a proper protection of the environment. Mathematical modelling and simulation of activated sludge systems have gained increasing attention in control engineering within the last years. The most widely used models to describe the biochemical processes that take place in a WWTP are the Activated Sludge Models 1–3. Due to their increased complexity, these models are often unsuited for control systems design. The aim of this paper is to develop reduced order models which can adequately describe the biochemical processes for the purpose of on-line control design. The models developed contain a minimum number of variables and parameters that allow for model identification and validation based on available on-line measurements.