EP0108478A1 - Stabilisation mechanisms - Google Patents

Stabilisation mechanisms Download PDF

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Publication number
EP0108478A1
EP0108478A1 EP83305180A EP83305180A EP0108478A1 EP 0108478 A1 EP0108478 A1 EP 0108478A1 EP 83305180 A EP83305180 A EP 83305180A EP 83305180 A EP83305180 A EP 83305180A EP 0108478 A1 EP0108478 A1 EP 0108478A1
Authority
EP
European Patent Office
Prior art keywords
pendulum
mass
centre
stabilisation
pivot point
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP83305180A
Other languages
German (de)
English (en)
French (fr)
Inventor
Ronald William Elston
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mcmichael Ltd
Original Assignee
Mcmichael Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mcmichael Ltd filed Critical Mcmichael Ltd
Publication of EP0108478A1 publication Critical patent/EP0108478A1/en
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/12—Supports; Mounting means
    • H01Q1/18—Means for stabilising antennas on an unstable platform

Definitions

  • the present invention relates to'stabilisation mechanisms and more particularly but not exclusively to such mechanisms for stabilising platforms and similar supports.
  • Providing stabilisation for ship based aerials requires compensation for pitch and roll of the ship which may be considered as simple harmonic movements and which are more usually compensated for by use of a passive system such as a simple or compound pendulum, an actively controlled system using axis drive motors to correct sensed angular changes or a gyroscopic system. Combinations of these three systems may also be used.
  • the pendulum system is comparatively less expensive and has lower maintenance costs but is only capable of giving relatively basic stabilisation.
  • Other motions for example complex sinusoidal motions such as may be caused by the bow of a ship riding a wave may result in the pendulum oscillating at a resonant frequency and taking a considerable time to re-settle.
  • fluid medium means a non-gaseous medium which is capable of flowing.
  • said pendulum in a stabilisation mechanism of the kind having a pendulum capable of movement about a pivot and the centre of mass of the pendulum disposed below the pivot, said pendulum includes a moveable mass arranged, in use, to respond to complex sinusoidal displacement of said pendulum by moving relative to the rest of said pendulum to cause an effective displacement of the centre of mass of the pendulum towards said pivot such that the fundamental frequency of the pendulum is altered to assist maintenance of the stabilisation of the mechanism over a broad operating range.
  • said moveable mass is a secondary pendulum which is mounted within the first said pendulum and which is capable of effective three dimensional movement with respect to the rest of said first pendulum.
  • the secondary pendulum may be an irregular planar member which is pivoted above its centre of mass and which is mounted for rotation within a cage, said cage being mounted for rotation transversely of the direction of rotation of said planar member such that in the static state of the stabilisation mechanism the planar member rests with the centre of mass thereof below its effective pivot point and on complex sinusoidal displacement of the first said pendulum said planar member may rotate effectively to move the centre of mass thereof towards the pivot point.
  • the moveable mass is a fluid medium (as hereinbefore defined), and the pendulum includes a plurality of compartments spaced around the vertical axis of said pivot, each of said compartments containing some of said fluid medium such that, in use, complex sinusoidal displacement of said pendulum causes a displacement of said fluid medium relative to said compartments to cause the effective displacement of the centre of mass towards said pivot.
  • the fluid medium may be mercury, water, dry sand or steel spheres for example.
  • the mechanism which is arranged to carry a platform (not shown) on which a ground based aerial (not shown) may be mounted has a fixed support 1 carrying a gimbal 13 which is attached by struts 2 and 12 to a pendulum 11.
  • the pendulum 11 is in the form of a hollow ring which is divided into a number of compartments 14 by dividing walls 3.
  • the pendulum 11 must be mounted such that its centre of mass is below the effective pivot point of the gimbal 13 to prevent the platform (not shown) becoming unstable.
  • Each of the compartments 14 is partially filled with a fluid 15 such as water or mercury for example.
  • pitch and roll of a ship for example are substantially simple harmonic movements. Accordingly it will be appreciated that the pendulum 11 will adopt a substantially simple harmonic compensating motion for pitch and roll and the fluid 15 will remain substantially stable in its location within the compartments 14, and this stable state is shown in Figure 2A to which reference is also now made.
  • the mechanism compensates for "pitch” and “roll” in the manner of a conventional pendulum stabilisation system.
  • the advantage of the present mechanism is in its response to a complex sinusoidal motion of the pendulum 11 such as might occur when a ship rides a large wave.
  • the pendulum 11 is shown as annular, any other desired shape of the pendulum may be adopted provided that the fluid 15 is restricted within compartments 14 around the pendulum.
  • the pendulum need not comprise a continuous series of compartments 14 around the pivot and could be provided by a number of compartments individually attached to the pivot.
  • the contents of the compartments 14 need not be liquids provided that the contents have sufficient mass and capability of flowing to effect movement of the effective centre of mass.
  • the fluid 15 may also be dry sand or glass or metal spheres for example.
  • the stabilisation mechanism shown has another method of reducing the effective length of the centre of mass below the pivot point which consists of a secondary pendulum within the primary.
  • the apparatus shown is a prototype pendulum constructed to prove the efficacy of such a stabilisation mechanism and comprises a support 20 attached to a base plate 21, the support 20 being connected by a rotational low-friction bearing 22 to a 'U' shaped support member 23 which in turn has rotational low-friction bearings 24 supporting the pendulum per se.
  • the pendulum has two degrees of freedom and the mass thereof may move to any point on a sphere surrounding its effective pivot point which is provided by the bearings 24 being transverse of the bearing 22, the pivot point being at the intersection of centre lines through the bearings.
  • the pendulum per se comprises a bob weight 25 on a shaft 26 connected by way of a supporting cage 27 (which is free to move with respect to the support 20 by its mounting in the bearings 24) to a shaft 28 which has a counterweight 29 thereon to represent for example the weight of an antenna mounted on the mechanism.
  • the bob weight 25 and the counterweight 29 are moveable with respect to their distance from the pivot point although in practice-a fixed length mounting would be provided.
  • the secondary pendulum comprises a disc member 30 from which a segment has been removed which member is rotationally mounted in a cage 32 at the nominal axis of the disc by a bearing 31.
  • the cage 32 is in turn rotationally mounted by bearings 33 in the cage 27.
  • the first pendulum comprising the bob weight 25, the shaft 26, the cage 27, the shaft 28 and the counterweight 29 will adopt a compensating simple harmonics movement about its axis by virtue of the bearings 22 and 24.
  • the attitude of the pendulum with respect to the earth remains substantially stable.
  • member 30 is a disc member having a segment thereof removed it will be realised that any planar member pivoted above its centre of mass could be used.
  • the secondary pendulum and its associated bearing mechanism could be provided by use of a sphere mounted for three dimensional movement and having an uneven distribution of its mass.
  • a radially extending bore of material is removed from the sphere making one area appreciably lighter in mass than the rest.
  • Such a bore may be infilled with a core of denser material or the sphere may have its two halves formed of differing material.
  • a partial sphere could also be used.
  • a hollow sphere partially filled with a fluid medium would suffice.
  • the stabilisation mechanism is mounted inside a fibre glass construction radome 40 (only part of which is shown) on a platform 41 which is arranged for horizontal rotation by means of a motor drive (not shown) such that an antenna 42 carried by the mechanism may be appropriately directed.
  • the radome 40 is for mounting on the masthead of a ship and is provided to prevent for example climatic effects or birds landing on the antenna 42 and affecting the balance of the mechanism.
  • connection plate 43 which carries a counterbalance weight 44 at the opposed end.
  • the connection plate 43 includes a channel 45 in which a spindle (not visible) runs to permit adjustment.
  • the angular direction of the antenna may then be fixed by tightening a wingnut 46 on to the end of the spindle to lock the connection plate 43.
  • the dimensions of the stabilisation mechanism's components may be varied to suit any particular installation. As an example for a ship whose typical parameters are
  • the disc member 30 has a weight of approximately one kilogram and comprises a 100 millimetre diameter disc truncated approximately twenty-five millimetres from the centre thereof.
  • the disc member 30 may be suitably manufactured from steel for example and would have a thickness of some twenty millimetres.
  • the invention may be actively implemented by providing sensors (not shown) which detect complex sinusoidal movement of the pendulum arrangement and control a mechanical shift of the centre of mass.
  • the shaft 26 is equipped with a collar at its suspension point from the cage 27 and a motor is controlled in response to the sensor to raise the shaft and bob weight 25 to effect the required change in the vertical distance (1) of the centre of mass below the effective pivot point.
  • An alternative active system uses a fluid medium in a container in place of the bob weight 25 and a further normally empty container mounted towards the pivot point and a pumping arrangement controlled by the sensor system to transfer the fluid medium between the two containers.
  • the mechanism may find use in ship-to-ship communications (for example where "line of sight” systems such as microwave communication is employed) and in communication between land based vehicles and satellites for example.

Landscapes

  • Support Of Aerials (AREA)
  • Vibration Prevention Devices (AREA)
  • Variable-Direction Aerials And Aerial Arrays (AREA)
  • Details Of Aerials (AREA)
  • Emulsifying, Dispersing, Foam-Producing Or Wetting Agents (AREA)
  • Micro-Organisms Or Cultivation Processes Thereof (AREA)
EP83305180A 1982-09-06 1983-09-06 Stabilisation mechanisms Withdrawn EP0108478A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8225344 1982-09-06
GB8225344 1982-09-06

Publications (1)

Publication Number Publication Date
EP0108478A1 true EP0108478A1 (en) 1984-05-16

Family

ID=10532720

Family Applications (1)

Application Number Title Priority Date Filing Date
EP83305180A Withdrawn EP0108478A1 (en) 1982-09-06 1983-09-06 Stabilisation mechanisms

Country Status (4)

Country Link
EP (1) EP0108478A1 (no)
JP (1) JPS5964902A (no)
GB (1) GB2127622B (no)
NO (1) NO833167L (no)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0440378A2 (en) * 1990-01-30 1991-08-07 Questus Technologies, Inc. Radar antenna mount
FR2870392A1 (fr) * 2004-05-14 2005-11-18 Mitsubishi Electric Corp Dispositif de suivi
WO2006064055A1 (en) * 2004-12-17 2006-06-22 Enrico Tacconi Device for rehabilitation of the limbs and of the trunk

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5512912A (en) * 1994-01-28 1996-04-30 Amsc Subsidiary Corporation Marine antenna mount

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2359877B2 (de) * 1972-12-01 1975-03-20 The Post Office, London Anordnung zur Regelung der Ausrichtung einer Richtempfangsantenne
US3968496A (en) * 1974-03-04 1976-07-06 International Standard Electric Corporation Stabilized antenna platform
DE2745755A1 (de) * 1976-10-08 1978-04-20 Hawker Siddeley Dynamics Ltd Stabilisierungseinrichtung fuer auf fahrzeugen anzuordnende geraete

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2359877B2 (de) * 1972-12-01 1975-03-20 The Post Office, London Anordnung zur Regelung der Ausrichtung einer Richtempfangsantenne
US3968496A (en) * 1974-03-04 1976-07-06 International Standard Electric Corporation Stabilized antenna platform
DE2745755A1 (de) * 1976-10-08 1978-04-20 Hawker Siddeley Dynamics Ltd Stabilisierungseinrichtung fuer auf fahrzeugen anzuordnende geraete

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0440378A2 (en) * 1990-01-30 1991-08-07 Questus Technologies, Inc. Radar antenna mount
EP0440378A3 (en) * 1990-01-30 1992-01-22 Questus Corporation Radar antenna mount
FR2870392A1 (fr) * 2004-05-14 2005-11-18 Mitsubishi Electric Corp Dispositif de suivi
WO2006064055A1 (en) * 2004-12-17 2006-06-22 Enrico Tacconi Device for rehabilitation of the limbs and of the trunk
JP2008523859A (ja) * 2004-12-17 2008-07-10 タッコニ・エンリコ 手足および胴体のリハビリテーション用装置

Also Published As

Publication number Publication date
NO833167L (no) 1984-03-07
GB2127622A (en) 1984-04-11
JPS5964902A (ja) 1984-04-13
GB2127622B (en) 1986-04-03
GB8323874D0 (en) 1983-10-05

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Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Designated state(s): DE FR IT NL SE

17P Request for examination filed

Effective date: 19840814

17Q First examination report despatched

Effective date: 19860220

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 19860701

RIN1 Information on inventor provided before grant (corrected)

Inventor name: ELSTON, RONALD WILLIAM