Biomedical subjects

Paolo Gardonio

Publications and source records attributed to Paolo Gardonio.

5 recordsLinked to original sources

PubMed2006

Active vibration control using an inertial actuator with internal damping.

Collocated direct velocity feedback with ideal point force actuators mounted on structures is unconditionally stable and generates active damping. When inertial actuators are used to generate the control force, the system can become unstable even for moderate velocity feedback gains due to an additional -180 degree phase lag introduced by the fundamental axial resonant mode of the inertial actuator. In this study a relative velocity sensor is used to implement an inner velocity feedback loop that generates internal damping in a lightweight, electrodynamic, inertial actuator. Simulation results for a model problem with the actuator mounted on a clamped plate show that, when internal relative velocity feedback is used in addition to a conventional external velocity feedback loop, there is an optimum combination of internal and external velocity feedback gains, which, for a given gain margin, maximizes vibration reduction. These predictions are validated in experiments with a specially built lightweight inertial actuator.

Journal Article↗

PubMed2005

Smart panels with velocity feedback control systems using triangularly shaped strain actuators.

In this paper we present a theoretical study on the active structural acoustic control of a new smart panel with sixteen triangularly shaped piezoelectric patch actuators, having their base edges evenly distributed along the perimeter of the panel, and velocity sensors positioned at the vertices opposite the base edges. The performance is assessed and contrasted with that of a conventional smart panel using a 4 x 4 array of square piezoelectric patch actuators evenly distributed over the surface of the panel with velocity sensors at their centers. For both systems the control effectiveness and stability of MIMO decentralized or SISO direct velocity feedback control architectures have been analyzed. The two control systems are arranged to generate active damping which reduces the response and sound radiation of the panel in the lightly damped and well separated low-frequency resonances. In particular the new control system can be seen as a set of sixteen "active wedges" which absorb energy from the incident flexural waves to the borders of the panel so that the panel could be considered anechoic. This study shows that the new arrangement with triangularly shaped actuators can achieve better control than the corresponding system using square actuators.

Journal Article↗

PubMed2002

Active vibroacoustic control with multiple local feedback loops.

When multiple actuators and sensors are used to control the vibration of a panel, or its sound radiation, they are usually positioned so that they couple into specific modes and are all connected together with a centralized control system. This paper investigates the physical effects of having a regular array of actuator and sensor pairs that are connected only by local feedback loops. An array of 4 x 4 force actuators and velocity sensors is first simulated, for which such a decentralized controller can be shown to be unconditionally stable. Significant reductions in both the kinetic energy of the panel and in its radiated sound power can be obtained for an optimal value of feedback gain, although higher values of feedback gain can induce extra resonances in the system and degrade the performance. A more practical transducer pair, consisting of a piezoelectric actuator and velocity sensor, is also investigated and the simulations suggest that a decentralized controller with this arrangement is also stable over a wide range of feedback gains. The resulting reductions in kinetic energy and sound power are not as great as with the force actuators, due to the extra resonances being more prominent and at lower frequencies, but are still worthwhile. This suggests that an array of independent modular systems, each of which included an actuator, a sensor, and a local feedback control loop, could be a simple and robust method of controlling broadband sound transmission when integrated into a panel.

Acoustics↗

PubMed2002

Coupling analysis of a matched piezoelectric sensor and actuator pair for vibration control of a smart beam.

This paper presents a theoretical and experimental study of the in-plane and out-of-plane coupling of a matched piezoelectric sensor/actuator pair bonded on a beam. Both the sensor and actuator are triangularly shaped polyvinylidene fluoride (PVDF) transducers and are intended to provide a compact sensor/actuator system for beam vibration control. The measured sensor-actuator frequency response function has shown an unpredicted increase in magnitude with frequency, which was found, to be due to in-plane vibration coupling. An analytical model has been developed to decompose the sensor-actuator response function into an in-plane contribution and an out-of-plane contribution. This in-plane coupling can limit the feedback control gains when a direct velocity feedback control is applied. A method called the j omega s compensation method is proposed to identify the effect of the in-plane vibration coupling at low frequencies. Even after this compensation, however, there was unexpected strong out-of-plane coupling at even modes, which may have been caused by a lack of accuracy in the shaping of the PVDF sensor and actuator. Numerical simulations have confirmed the sensitivity of the matched sensor/actuator pair with shaping errors.

Journal Article↗

PubMed2002

Novel active noise-reducing headset using earshell vibration control.

Active noise-reducing (ANR) headsets are available commercially in applications varying from aviation communication to consumer audio. Current ANR systems use passive attenuation at high frequencies and loudspeaker-based active noise control at low frequencies to achieve broadband noise reduction. This paper presents a novel ANR headset in which the external noise transmitted to the user's ear via earshell vibration is reduced by controlling the vibration of the earshell using force actuators acting against an inertial mass or the earshell headband. Model-based theoretical analysis using velocity feedback control showed that current piezoelectric actuators provide sufficient force but require lower stiffness for improved low-frequency performance. Control simulations based on experimental data from a laboratory headset showed that good performance can potentially be achieved in practice by a robust feedback controller, while a single-frequency real-time control experiment verified that noise reduction can be achieved using earshell vibration control.

Ear Protective Devices↗