Patent EP0348087A2 successfully refreshed from Google Patents.
EP0348087A2
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EP
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Method and apparatus for cancelling vibrations
Assignee: Litton Marine Systems Inc
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Filing: 1989-06-13
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Granted: —
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Expires: 2009-06-13
Abstract
Abstract A dynamic vibration absorber for reducing vibrations of a platform (19) induced by an oscillating mass (17) mounted thereon is provided by mounting a mass (12) of equal mechanical resonant frequency as that of the oscillating mass and oscillating this mass in a manner to establish an equal and opposite vibration of the platform (19), thereby cancelling the vibrations induced by the oscillating mass (17). In one embodiment, a signal from the oscillating mass (12) representative of the frequency and amplitude of its mechanical oscillation is phase shifted and utilised as a driving signal to the drive motor of the absorber mass. In another embodiment, electrical signals representative of the platform vibrations are detected to provide phase and amplitude vibration error signals. These error signals are applied to a reference signal coupled to the drive motor of the canceller mass causing the oscillations of the canceller mass to induce vibrations in the platform which counter the vibrations induced by the oscillating mass.
Inventors
- 👤 Charles M. Adkins
- 👤 James R. Brazell
- 👤 Gerard T. Mayer
- 👤 Henry C. Stacey
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-31 19:43
CPC Classifications
F; F16; F16F; F16F7/00; F16F7/10; F16F7/1005; G; G01; G01C; G01C19/00; G01C19/58; G01C19/64; G01C19/66; G01C19/68; G01C19/70; F16F2224/00; F16F2224/02; F16F2224/0283
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
61 words
Apparatus for countering vibrations of a platform (19) induced by an oscillating mass (17) mounted thereon characterised in that it comprises: mass means (10,12) mechanically coupled to the platform (19); and mass oscillation means (11) coupled to the mass means for oscillating the mass means in a manner to counter vibrations of the platform (19) induced by the oscillating mass (17).
Claim 2
Dependent Claim
61 words
Apparatus for countering vibrations of a platform (19) induced by an oscillating mass (17) mounted thereon characterised in that it comprises: mass means (10,12) mechanically coupled to the platform (19); and mass oscillation means (11) coupled to the mass means for oscillating the mass means in a manner to counter vibrations of the platform (19) induced by the oscillating mass (17).
Claim 3
Dependent Claim
28 words
Apparatus according to claim 1, characterised in that the mass means (12) is constructed to have a mechanical resonant frequency equal to that of the oscillating mass (17).
Claim 4
Dependent Claim
110 words
Apparatus according to claim 1 or 2, characterised in that the oscillating mass (12) includes pick-off means (15d) operable to provide electrical signals representative of movements of the oscillating mass (12) and in that the mass oscillation means (12) comprises oscillator means (15a-15c) having drive input means for oscillating the mass means (12) in accordance with electrical signals coupled to the drive input means; and phase shift means (23) coupled between the pick-off means (15d) and the drive input means for providing a phase shift to electrical signals coupled from the pick-off means (15d) to the drive input means, the phase shift being chosen to minimise vibrations of the platform.
Claim 5
Dependent Claim
127 words
Apparatus according to claim 1 or 2, characterised in that it includes: oscillator means (15a-15c) for mechanically oscillating the mass means (12), the oscillator means having pick-off means (15d) operable to provide electrical signals representative of mechanical oscillations of the mass means, and drive input means for receiving driving electrical signals; accelerometer means (27) mounted on the platform (19) for providing electrical signals representative of platform vibrations; and vibration control means (29) coupled to receive signals from pick-off means of the oscillating mass, signals from the pick-off means (15d) of the oscillator means, and signals from the accelerometer means for providing controls signals to the drive input means (63) to oscillate the mass means in a manner to counter vibrations induced by oscillations of the oscillating means.
Claim 6
Dependent Claim
131 words
Apparatus according to claim 4, characterised in that the vibration control means comprises: means (47) coupled to the pick-off means of the oscillating mass (17) for providing a first reference signal in-phase with a signal at the pick-off means of the oscillating mass; means (49, 51) coupled to the pick-off means (15d) of the oscillating mass for providing a second reference signal phase shifted by a predetermined phase angle relative to the signal at said pick-off means of said oscillating mass; and means (53, 55) coupled to receive the first and second reference signals and electrical signals from the accelerometer means (27) for providing drive signals to the drive input means (63) to oscillate the mass means and induce vibrations that counter the vibrations induced by oscillations of the oscillating means.
Claim 7
Dependent Claim
113 words
Apparatus according to claim 5, characterised in that the drive signal means includes: means (57) for detecting the electrical signals from the accelerometer means (27) relative to the first and second reference signals to provide amplitude and phase error signals; means (59) coupled to receive the phase and amplitude error signals for providing drive reference signals in accordance with the phase and amplitude error signals; and means (61) coupled to receive the reference drive signals and signals from the pick-off (15d) of the oscillator means for comparing the signals from said pick-off means of the oscillator means with the reference drive signals for providing the drive signals to the drive input means (63).
Claim 8
Dependent Claim
15 words
Apparatus according to claim 5 or 6, characterised in that the phase angle is 90°.
Claim 9
Dependent Claim
26 words
Apparatus according to any of the preceding claims, characterised in that the mass means (10) is mounted between the oscillating mass (17) and the platform (19).
Claim 10
Dependent Claim
24 words
Apparatus according to any of the preceding claims, characterized in that the mass means (10) is mounted in a recess of the platform (19).
Claim 11
Dependent Claim
45 words
Apparatus according to any of the preceding claims, characterised in that the oscillating mass (17) is mounted on a first surface of the platform (19) and the mass means (10) is mounted on a second surface of that platform that is opposite said first surface.
Claim 12
Independent Claim
56 words
A method for countering vibrations of a platform induced by motions of an oscillating mass mounted thereon, characterised in that it comprises the steps of: mounting mass means (10) on the platform (19); and oscillating the mass means in a manner that induces vibrations that counter the vibrations induced by motions of the oscillating means (17).
Claim 13
Independent Claim
56 words
A method for countering vibrations of a platform induced by motions of an oscillating mass mounted thereon, characterised in that it comprises the steps of: mounting mass means (10) on the platform (19); and oscillating the mass means in a manner that induces vibrations that counter the vibrations induced by motions of the oscillating means (17).
Claim 14
Dependent Claim
100 words
A method according to claim 11, characterised in that the step of oscillating the mass means comprises the steps of: mounting motor means (11) on the mass means (10); providing signals from the oscillating mass that are representative of motions of the oscillating mass; phase shifting the signals provided from the oscillating mass to provide phase shifted signals; and coupling the phase shifted signals to the motor means for causing the mass means to oscillate in accordance with the phase shifted signals, oscillations of the mass means inducing vibrations of the platform that counter vibrations induced by the oscillating mass.
Claim 15
Dependent Claim
141 words
A method according to claim 11 or 12, characterised in that the step of oscillating the mass means comprises the steps of: generating a first reference signal in-phase with a signal representative of the motions of the oscillating means (17); generating a second reference signal phase shifted by a predetermined phase angle relative to said representative signal; providing a signal representative of vibrations of the platform (19); synchronously detecting the vibration representative signal relative to the first and second reference signals to obtain phase and amplitude error signals; processing the phase and amplitude error signals to generate a drive reference signal; and coupling the drive reference signal to motor means (11) coupled to the mass means for oscillating said mass means in a manner to induce vibrations of the platform (19) that counter vibrations thereof induced by the oscillating mass (17).
References Cited (Backward Citations)
No citation records indexed.
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