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Active vibration control using a nonlinear inertial actuator

Active vibration control using a nonlinear inertial actuator
Active vibration control using a nonlinear inertial actuator
This thesis presents a theoretical and experimental study of a stroke limited inertial actuator used in active vibration control. The active control system under investigation consists of an inertial actuator attached to a lightweight flexible structure, a collocated vibration sensor and a velocity feedback controller (VFC). Since the control force is generated by accelerating the proof mass, controlling low frequency motions or large amplitude vibrations requires a very long stroke for the proof mass. One of the main limitations of inertial actuators is that the stroke length is finite, however. This not only limits the amount of force available from the actuator but also when the proof mass hits the end-stops it causes impulse-like excitations that are transmitted to the structure and may result in damage. Additionally, the shocks produced by the impacts between the proof mass and the end-stops are in phase with the velocity of the structure, leading to a reduction of the overall damping of the system, which can give rise to instability of the system and limit cycle oscillations.

This research examines the implementation of a nonlinear feedback controller to avoid collisions of the proof mass with the actuator’s end-stops, thus preventing this instability.

The nonlinear model of a stroke limited inertial actuator is first identified using base and direct excitation experiments and a parameter estimation process. A nonlinear feedback control (NLFC) strategy is then presented, which actively increases the internal damping of the actuator when the proof mass approaches the end-stops. The experimental implementation of the NLFC is investigated for the control of a cantilever beam, and it is shown that the robustness of the VFC system to external perturbations is much improved with the NLFC. Finally, a virtual sensing approach based on an extended Kalman filter algorithm is discussed for the real-time estimation of the states of the proof mass that is used to calculate the feedback signal of the NLFC. It is shown experimentally that larger velocity feedback gains can be used without the system becoming unstable when the NLFC is adopted and the theoretical reasons for this increase in stability margin are explored.
University of Southampton
Dal Borgo, Mattia
7eeac32d-7dc9-4645-89cc-acee5a293867
Dal Borgo, Mattia
7eeac32d-7dc9-4645-89cc-acee5a293867
Ghandchi Tehrani, Maryam
c2251e5b-a029-46e2-b585-422120a7bc44

Dal Borgo, Mattia (2019) Active vibration control using a nonlinear inertial actuator. University of Southampton, Doctoral Thesis, 204pp.

Record type: Thesis (Doctoral)

Abstract

This thesis presents a theoretical and experimental study of a stroke limited inertial actuator used in active vibration control. The active control system under investigation consists of an inertial actuator attached to a lightweight flexible structure, a collocated vibration sensor and a velocity feedback controller (VFC). Since the control force is generated by accelerating the proof mass, controlling low frequency motions or large amplitude vibrations requires a very long stroke for the proof mass. One of the main limitations of inertial actuators is that the stroke length is finite, however. This not only limits the amount of force available from the actuator but also when the proof mass hits the end-stops it causes impulse-like excitations that are transmitted to the structure and may result in damage. Additionally, the shocks produced by the impacts between the proof mass and the end-stops are in phase with the velocity of the structure, leading to a reduction of the overall damping of the system, which can give rise to instability of the system and limit cycle oscillations.

This research examines the implementation of a nonlinear feedback controller to avoid collisions of the proof mass with the actuator’s end-stops, thus preventing this instability.

The nonlinear model of a stroke limited inertial actuator is first identified using base and direct excitation experiments and a parameter estimation process. A nonlinear feedback control (NLFC) strategy is then presented, which actively increases the internal damping of the actuator when the proof mass approaches the end-stops. The experimental implementation of the NLFC is investigated for the control of a cantilever beam, and it is shown that the robustness of the VFC system to external perturbations is much improved with the NLFC. Finally, a virtual sensing approach based on an extended Kalman filter algorithm is discussed for the real-time estimation of the states of the proof mass that is used to calculate the feedback signal of the NLFC. It is shown experimentally that larger velocity feedback gains can be used without the system becoming unstable when the NLFC is adopted and the theoretical reasons for this increase in stability margin are explored.

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Published date: February 2019

Identifiers

Local EPrints ID: 432262
URI: http://eprints.soton.ac.uk/id/eprint/432262
PURE UUID: 531275bb-1ec5-4f24-857c-ac10946cced2
ORCID for Mattia Dal Borgo: ORCID iD orcid.org/0000-0003-4263-0513

Catalogue record

Date deposited: 05 Jul 2019 16:30
Last modified: 21 Sep 2019 00:30

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Contributors

Author: Mattia Dal Borgo ORCID iD
Thesis advisor: Maryam Ghandchi Tehrani

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