Geometrical instruments – Indicator of direction of force traversing natural media – Gyroscopically controlled or stabilized
Patent
1983-01-12
1985-07-23
Haroian, Harry N.
Geometrical instruments
Indicator of direction of force traversing natural media
Gyroscopically controlled or stabilized
G01K 17384
Patent
active
045301646
DESCRIPTION:
BRIEF SUMMARY
The invention relates to gyrocompasses for sea-going vehicles, more especially for merchant ships, i.e. for civil applications in which questions of price assume a certain importance (in opposition to military applications).
Gyrocompasses are known comprising a two gimbal pendular mechanism, namely a roll gimbal and a pitch gimbal, this pendular mechanism supporting a suspended lower gimbal.
This suspended lower gimbal carries a free gyroscope housed in a sealed enclosure disposed inside an external enclosure filled with a floatation liquid and integral with the suspended lower gimbal.
Centering of the sealed enclosure inside the outer enclosure may be obtained by electric means (repulsion coil devices), by hydrostatic means (floatation liquids of different density) or by mechanical means (torsion bars).
In all cases, the outer enclosure has a vertical axis of rotation because it is suspended, through the lower gimbal, from the pendular mechanism; this outer enclosure is controlled to follow in azimuth the direction of the axis of rotation of the gyroscope.
The free gyroscopes used are gyroscopes with two degrees of freedom, which have both a possibility of free rotation in azimuth between the gyroscope and the outer enclosure containing the liquid (possibility of rotation sometimes limited to a few degrees), and a possibility of rotation in elevation (possibility of rotation generally less than or equal to 20.degree.); however, only angular azimuth detection exists between the two, which allows control of the enclosure in azimuth. The gyroscope behaves then finally, for a half, like a free gyroscope and, in particular, it is then subjected to all the horizontal disturbing torques because of the friction and of the elevational movements of the outer enclosure which is pendular during rolling and pitching.
So, such a gyroscope must then be given a very high kinetic moment (of the order of 10.sup.6 c.g.s.) so that it may resist these horizontal disturbing torques; this leads to gyroscopes whose rotors have high masses (at least 500 g).
Moreover, the axis of rotation of the gyroscope remains horizontal and constantly oriented in a North-South direction, which makes the gyrocompass sensitive to a fixed drift of the gyroscope which creates a permanent unknown heading error.
The aim of the present invention is to provide a gyro-compass whose gyroscope has a much lower kinetic moment (of the order of 10.sup.4 c.g.s.) which may be 100 times smaller than the kinetic moment of the gyroscopes used in gyrocompasses known at present.
A further aim of the invention is to provide a gyrocompass alllowing Azimuth and elevation control and not only azimuth control as in the gyrocompasses known at present.
A further aim of the invention is to provide a gyrocompass in which the axis of rotation of the gyroscope is no longer constantly orientated in a North-South direction but on the contrary driven with a uniform angular speed while remaining in the horizontal plane.
Yet another aim of the invention is to provide a gyrocompass whose gyroscope may have very low drift stability performances, so be a low-priced gyroscope, with a long useful life (because of the low load on the bearings) and having excellent resistance to shocks and vibrations.
According to the invention, the gyrocompass comprises:
a two gimbal pendular mechanism, namely a roll gimbal and a pitch gimbal,
a vertical fork cooperating freely with said pendular mechanism,
an elevation gimbal carried by said fork,
a gyroscope having two degrees of freedom carried by this elevation gimbal, so that one of its two axes of sensitivity is vertical, the other axis of sensitivity is parallel to the axis of the elevation gimbal and its axis of rotation is horizontal,
a detector of horizontality carried by this elevation gimbal, so that its axis of sensitivity is parallel to the axis of rotation of the gyroscope,
the vertical fork being azimuth controlled by the position detectors of the vertical axis of sensitivity of the gyro,
the elevation gimbal being controlled in elevati
REFERENCES:
patent: 1925138 (1933-09-01), Dillman
patent: 3229376 (1966-01-01), Wilcox
patent: 3292269 (1966-12-01), Brugger
patent: 4443952 (1984-04-01), Schulien
Haroian Harry N.
Societe d'Applications Generales d'Electricite et de Mecanique S
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