A New Approach to Active Vibration Suppression
Lead Research Organisation:
University of Liverpool
Department Name: School of Engineering
Abstract
Active Vibration Suppression is the area of research at the intersection of two mostly independent disciplines, Structural Mechanics and Active Control. The dynamic behaviour of large flexible systems such as bridges, buildings and aerospace structures generally involves many natural frequencies and modes; in theory an infinite number in continuous structures. In two important respects the available structural-dynamics (finite element) models are unsuitable for use with conventional active control (state-space) methods; they are too large and do not represent damping accurately enough. This problem is addressed by a new approach to active vibration suppression using measured receptances. The method, which may be cast an inverse problem, offers a completely fresh theoretical viewpoint, with attendant new understanding. The theory has its origins in structural dynamics, whereas generally in active vibration suppression, theory developed by the active control community is applied to structural vibration problems. The method developed is generic, having wide applications and not limited to particular types of structures. It addresses a problem that is presently very difficult to tackle with existing methods. It is not limited by physical size or complexity, and does not rely on (possibly inaccurate) mathematical models. The research will include not only the theoretical development of a completely new approach but also the demonstatation of practical usefulness of the theory in laboratory tests, rotor simulations and helicopter ground vibration tests. The research will be carried out in close collaboration with engineering scientists from Westland Helicopters Ltd.
People |
ORCID iD |
John Mottershead (Principal Investigator) |
Publications
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Ghandchi Tehrani M
(2011)
Robust pole placement in structures by the method of receptances
in Mechanical Systems and Signal Processing
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Ghandchi Tehrani M
(2010)
Partial pole placement in structures by the method of receptances: Theory and experiments
in Journal of Sound and Vibration
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Mottershead J
(2009)
Assignment of eigenvalue sensitivities from receptance measurements
in Mechanical Systems and Signal Processing
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Mottershead J
(2009)
Special issue on 'Inverse Problems in MSSP'
in Mechanical Systems and Signal Processing
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Mottershead J
(2011)
Active vibration control experiments on an AgustaWestland W30 helicopter airframe
in Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science
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Ram Y
(2009)
State feedback control with time delay
in Mechanical Systems and Signal Processing
Description | The project was concerned with the problem of vibration suppression by a new technique for active pole-zero placement using vibration data in the form of frequency response functions, such as receptances as measured in a modal test (or in a ground vibration test). The most important point about this approach is that it is based upon measurements and not on a mathematical model, which might not be readily available or is likely to be inaccurate. It is not necessary to have a mathematical model of the system and it is not necessary to model the dynamics of the actuators and sensors, which can be included in the measurement. Methods were developed for the placement of chosen poles (natural frequencies and damping values) while other poles were unchanged. This is the problem of partial pole placement, which although well-known in the conventional control theory had been impractical because of the restriction to systems of finite dimension with measurement of the full state vector. Use of the new measurement based approach enabled the removal of this restriction and practical application of partial pole placement was demonstrated using two different laboratory-based test rigs (one using electro-magnetic actuators and ICP accelerometers, the other using MFC distributed piezo-strip actuators and sensors). One application of partial pole placement is in the avoildance of resonances. Methods for the robust assignment of poles in the presence of measurement noise were developed and shown to be effective in simulated experiments. Finally the technique was applied to a W30 helicopter airframe in the AgustaWestland vibration test-house at Yeovil. Tests were carried out and control implemented over two weeks spent on-site in February and March 2011. This work (on the W30) has since been published in the Journal of Mechanical Engineering Science (Proc. IMech E Part C). |
Exploitation Route | The research is applicable to a very wide range of practical vibration suppression problems. It is particularly useful to problems involving persistent harmonic excitation, such as the excitation of a helicopter airframe from the rotor blades, which operate at a constant blade-passing speed. Integer multiples of this speed can lead to resonances which must be treated either passively or actively. Passive methods generally involve additional mass and are restricted by the strucure of the airframe (e.g. added beams can only be placed in a very limited number of locations). Active methods are not restricted by the configuration of the airframe structure. |
Sectors | Aerospace Defence and Marine Construction Transport Other |
Description | Active control of an AgustaWestland W30 Airframe was demonstrated using the receptance method developed in this research programme. |
First Year Of Impact | 2011 |
Sector | Aerospace, Defence and Marine |
Impact Types | Societal Economic |
Description | Doctoral Training Grant |
Amount | £3,960,000 (GBP) |
Funding ID | EP/L015927/1 |
Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
Sector | Public |
Country | United Kingdom |
Start |
Description | European Office of Aerospace Res and Dev. |
Amount | £13,625 (GBP) |
Funding ID | FA8655-10-1-3054 |
Organisation | European Office of Aerospace Research & Development (EOARD) |
Sector | Public |
Country | United Kingdom |
Start | 08/2010 |
End | 10/2012 |
Description | Nonlinear Active Vibration Suppression in Aeroelasticity |
Amount | £527,434 (GBP) |
Funding ID | EP/J004987/1 |
Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
Sector | Public |
Country | United Kingdom |
Start | 01/2012 |
End | 07/2015 |
Description | Receptance Method in Active Vibration Control |
Organisation | Louisiana State University |
Department | Department of Mechanical and Industrial Engineering |
Country | United States |
Sector | Academic/University |
PI Contribution | This is a long-term collaboration on theoretical aspects of active vibration control. Prof Y.M. Ram and I have worked closely on this for around 10 years. |
Collaborator Contribution | This is a long-term collaboration on theoretical aspects of active vibration control. Prof Y.M. Ram and I have worked closely on this for around 10 years. |
Impact | Several joint publications. |
Description | Dynamical Inverse Problems: Theory and Application |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | Yes |
Geographic Reach | International |
Primary Audience | Other academic audiences (collaborators, peers etc.) |
Results and Impact | Five lectures on 'Inverse Problems in Structural Modification and Active Eigenvalue Assignment in Structures by the Receptance Method'. Presented at the International Centre for Mechanical Sciences (CISM), Udine, Italy. The Broglio Session. Led to several requests for further information related to my research (from academics and researchers). |
Year(s) Of Engagement Activity | 2009 |