Auto-adaptive velocity feedback for active isolation of random vibrations in subcritical 2 dof systems

Alujević, Neven and Wolf, Hinko and Domazet, Željko (2012) Auto-adaptive velocity feedback for active isolation of random vibrations in subcritical 2 dof systems. = Auto-adaptive velocity feedback for active isolation of random vibrations in subcritical 2 dof systems. In: International Conference on Noise and Vibration Engineering, 17.-19.2012., Leuven, Belgija.

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Auto-adaptive velocity feedback for active isolation of random vibrations in subcritical 2 dof systems.pdf - Published Version Jezik dokumenta:Croatian

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Abstract

Skyhook damping is an active vibration isolation method, which can also be used to reduce vibration transmission between masses in lumped parameter 2 degree of freedom (dof) systems. The method is based on measuring the absolute velocity of the clean body, multiplying it by a negative gain, and feeding the result back to a force actuator reacting between the clean and the dirty body. In such a way disturbances coming onto the clean body from the dirty body can be successfully rejected in a broad frequency band. However, the method is only suitable if the feedback loop is unconditionally stable such that appropriately high feedback gains can be applied. It has been previously shown that passive 2 dof systems can be classified as so called sub- or supercritical based on whether the skyhook damping loop is conditionally or unconditionally stable. For subcritical systems the absolute velocity feedback loop is conditionally stable and a skyhook damping approach is consequently not appropriate due to a control spillover effect at the first resonance frequency. In such a case the feedback loop can be stabilized by including an appropriate amount of relative damping between the clean and the dirty body in addition to the skyhook damping. This approach has been referred to as blended velocity feedback. In this paper the application of the blended velocity feedback on subcritical 2dof systems is investigated using an auto-tuning controller. An algorithm to gradually change the relative and absolute feedback gains until the active isolation performance reaches its best by applying an optimal combination of the two gains is applied. It is shown that there is only one such optimal combination, that is, the performance surface has a global minimum. Furthermore there are no local minima so a trial and error algorithm can be applied. Although in the frequency domain finding the minimum of the performance surface is straightforward, in the time domain the determining the clean body mean squared velocity can take a considerable time per step of the algorithm, such that the convergence of the trial and error algorithm can be relatively slow. It is hypothesized that a model based approach in determining the step size may speed-up the convergence.

Item Type: Conference or Workshop Item (Lecture)
Keywords (Croatian): active control, noise, vibration, reactive actuators
Subjects: TECHNICAL SCIENCE > Traffic and transportation
Divisions: 200 Department of Engineering Mechanics > 230 Chair of Mechanical Systems Dynamics
600 Department of Naval Engineering and Marine Technology > 620 Chair of Marine Structures Design
Indexed in Web of Science: Yes
Indexed in Current Contents: No
Citations JCR: 0 (15.12.2017.)
Citations SCOPUS: 0 (15.12.2017.)
Date Deposited: 25 Apr 2016 08:14
Last Modified: 15 Dec 2017 12:54
URI: http://repozitorij.fsb.hr/id/eprint/5770

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