Search results for "Control theory"
showing 10 items of 1333 documents
Comparing different control strategies for indoor thermal comfort aimed at the evaluation of the energy cost of quality of building
2010
Abstract The rapid improvement in the standard of living requires more detailed and sophisticated methods of evaluating comfort conditions. But, maintaining thermal comfort conditions in confined environments may require complex regulation procedures and the proper management of heating, ventilating and air conditioning (HVAC) systems. In turn, the requirements for indoor thermal comfort do not necessarily coincide with those of energy saving purposes, which in the last years are becoming a crucial issue owing to the enactment of the European Energy Performance of Buildings Directive (EPBD). The aim of this work is to compare different indoor control thermal comfort strategies in view of th…
Type-2 fuzzy control of a fed-batch fermentation reactor
2010
Abstract The aim of the paper is to present the application of type-2 fuzzy logic controllers (T2FLCs) to the control of a fed-batch fermentation reactor in which the penicillin production is carried out. The performance of the control system using T2FLCs is compared by simulation with that of a control system using type-1 fuzzy logic controllers (T1FLCs). The non linear model used for the simulation study is an unstructured model characterized by the presence of non linearities, parameter uncertainty and measurement noise. Simulation results confirm the robustness of the T2FLC which shows a better performance than its type-1 counterpart particularly when uncertainties are present in the co…
Control of the Biodegradation of Mixed Wastes in a Continuous Bioreactor by a Type-2 Fuzzy Logic Controller
2009
Abstract Type-2 fuzzy logic control is proposed for nonlinear processes characterized by bifurcations. A control simulation study was conducted for a bioreactor with cell recycle containing phenol and glucose as carbon and energy sources in which a pure culture of Pseudomonas putida is carried out. The model developed by Ajbar [Ajbar, A. (2001). Stability analysis of the biodegradation of mixed wastes in a continuous bioreactor with cell recycle. Water Research, 35 (5), 1201–1208] was used for the simulations. The particular dynamics of the bioreactor, characterized by two saddle-node bifurcations, makes its control difficult, since it may become unstable also for small variations of some p…
Nonlinear control of an activated sludge aeration process: use of fuzzy techniques for tuning PID controllers
1999
In this paper, several tuning algorithms, specifically ITAE, IMC and Cohen and Coon, were applied in order to tune an activated sludge aeration PID controller. Performance results of these controllers were compared by simulation with those obtained by using a nonlinear fuzzy PID controller. In order to design this controller, a trial and error procedure was used to determine, as a function of error at current time and at a previous time, sets of parameters (including controller gain, integral time and derivative time) which achieve satisfactory response of a PID controller actuating over the aeration process. Once these sets of data were obtained, neural networks were used to obtain fuzzy m…
A mixed H<inf>2</inf>/H<inf>&#x221E;</inf>-based semiactive control for vibration mitigation in flexible structures
2009
In this paper, we address this problem through the design of a semiactive controller based on the mixed H 2 /H ∞ control theory. The vibrations caused by the seismic motions are mitigated by a semiactive damper installed in the bottom of the structure. It is meant by semiactive damper, a device that absorbs but cannot inject energy into the system. Sufficient conditions for the design of a desired control are given in terms of linear matrix inequalities (LMIs). A controller that guarantees asymptotic stability and a mixed H 2 /H ∞ performance is then developed. An algorithm is proposed to handle the semiactive nature of the actuator. The performance of the controller is experimentally evalu…
Investigation of motor current signature and vibration analysis for diagnosing rotor broken bars in double cage induction motors
2012
This paper investigates the detectability of rotor broken bars in double cage induction motors using current signature and vibration analysis techniques. Double cage induction motors are commonly used for applications where successive loaded starts-up are mandatory. Experimental results were performed under healthy and faulty cases, and for different load conditions using each technique. Rotor broken bars fault detection based on sideband current components may fails due to the presence of inter bar currents that reduce the degree of rotor asymmetry, yielding to a decrease of the magnitude of these spectral components. But inter bar currents produce core vibrations in the axial direction, w…
PMSM Drives Sensorless Position Control with Signal Injection and Neural Filtering
2009
Vector Field Oriented Control (FOC) is one of the best control methods for high-dynamic electrical drives. To avoid the adoption of the speed/position sensor (resolver/encoder), a sensorless technique should be used. Among the various sensorless methods in literature, those based on machine saliency detection by signal injection seem to be most useful for thier giving the possibility of closing the position control loop. This paper proposes a method for enhancing both rotating and pulsating voltage carrier injection methods by a neural adaptive band filter. Results show the goodness of the proposed solution.
Immunity of a Virtual Instrument to conducted electromagnetic disturbances
2004
In the paper the performances of the Virtual Instruments under conducted electromagnetic disturbances are investigated, in order to find out if and how their metrological characteristics change with respect to the ones measured in absence of electromagnetic threats. The analysis is carried out by means of experimental tests, subjecting the AC power port of the systems under test to the conducted disturbances considered by the IEC-61326 standard and following the test procedures prescribed in the IEC-61000-4-series standards. The results show that the tested measurements instruments are sufficiently immune to these disturbances, since no variations of the distinctive parameters have been obs…
Nonlinear Control of a Pneumatic Muscle Actuator System
2001
Abstract The performance of a Pneumatic Muscle Actuator under three tracking control strategies is compared: robust backstepping, sliding-mode and gain scheduling. Robustness is assured for the three controllers in the presence of model uncertainties and external perturbations. Exponential stability is proved for the sliding-mode tracking controller, ultimate boundedness for the backstepping tracking controller and exponential stability for constant or slowly-varying reference signals for the gain scheduling controller. Computer simulations show a good performance for the tracking of a sine wave by the first two controllers, although the sliding-mode strategy yields a high-frequency switchi…
Sliding mode torque control of an induction motor for automotive application with sliding mode flux observer
2016
In this paper, the performance of two control systems of induction motors for automotive applications were compared in order to highlight the differences in terms of response speed, robustness and noise immunity. The first system is realized through a field-oriented control with PI controllers, while the second system is realized through a field-oriented control with Sliding Mode Controllers. Both controls are designed to follow the torque references as required for the vehicles and are tested with typical load profiles of vehicles. It also designed a sliding mode observer flux.