Browsing by Subject "feedback control"

Now showing 1 - 2 of 2

Access status: Open Access ,
Modelling and control of structure-acoustic interaction problems via piezoceramic actuators
(Wydawnictwa AGH, 2005) Leniowska, Lucyna
Active control of vibration suppression of a circular fluid-loaded plate is analytically studied. The purpose of this theoretical work is to present a general model of a planar vibrating structure located in a finite baffle and interacted with fluid as well as its time response on harmonic excitation when a control strategy is applied. The structure under study is a vibrating circular plate of radius a, having a constant thickness h, to which centrally placed circular shaped piezoeleetric ceramic patches of radius a1 a are bonded. They are used to cancel the plate vibrations and related sound field when a controlling voltage is applied. It was assumed, that the plate clamped at the edge is excited on one side by a uniform periodic force with a constant amplitude F0 and it radiates the acoustic waves into a surrounded fluid of density Po. The control problem lies in using piezoceramic actuators working in a pair to reduce the plate vibrations. For the system under consideration the state-space model is constructed. The modern control theory is then applied to the system model using a linear quadratic regulator (LQR). The simulations of the active attenuation of the plate vibrations were made with a MATLAB/Simulink computer program, The results demonstrate that it is possible to achieve a significant reduction of the vibration amplitude with the use of a pair PZT actuators.
Access status: Open Access ,
Multi-channel virtual-microphone feedback minimum-variance active noise control system
(Wydawnictwa AGH, 2009) Pawełczyk, Marek
Classical active noise control systems are designed to minimise, in a sense, the residual signal at the microphone providing information about acoustic noise and secondary sound interference. The secondary sound operates at the same time on the acoustic noise at other positions including user ears. In the worst case this can result in sound reinforcement at those positions. In many applications placing another microphone directly at the ears is not accepted. It is then justified to make efforts to design a dedicated system. The purpose is to minimise the mean-square value of the noise at the desired location while performing measurements of sound interference results at another location. This can be done by employing the general idea of Vrtual-Microphone Control systems. However, for many active noise control applications the use of a single pair of microphone and loudspeaker does not suffice to obtain satisfactory performance, i.e. generate a zone of quiet of acceptable dimensions. Moreover, for some applications, presence of an obstacle, e.g. the head in an active headrest system, constitutes a barrier for the zone of quiet at one side to propagate to the other side. Therefore, more microphones and loudspeakers are often necessary. In the most general case a coupling between subsequent pairs should be taken into account resulting in a multi-channel system. In previous papers of the author adaptive systems have been designed and analysed. In this paper a fixed parameter multi-channel Virtual-Microphone Control system, optimal in the mean- square sense, is designed. It includes non-minimum phase property of the system channels. Both the case of more inputs than outputs as well as the case of more outputs than inputs are considered. Factorization techniques have been used for the design. The system is verified by successfully controlling noise for the active headrest system.