Machine element or mechanism – Gyroscopes – Gyroscope control
Patent
1979-11-03
1983-03-29
Bonck, Rodney H.
Machine element or mechanism
Gyroscopes
Gyroscope control
74 58, G01C 1950
Patent
active
043779506
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a vertical gyro erector.
From a certain standpoint, prior art erectors for vertical gyros can be divided into two major classes:
Erectors which exert torques of a continuous nature and which are usually electrical or pneumatic;
Rotating mechanical erectors which exert gravity-induced torques of a pulsed nature.
This latter class includes erectors of the type described in French Pat. No. 1,416,416 granted on Sept. 27, 1965.
The difference in manner of operation of these two classes of erectors entails consequences which are due to the fact that the effective erecting torques, that is to say those which cause the required rate of precession or rate of erection are in reality equal to the torques due to the action of the erector less the parasite torques ascribable to the inevitable friction on the gyroscope suspension axes.
It is customary to seek low erection rates in order to minimize errors due to accelerations of the carrier vehicle. However, one is restricted in this respect, firstly in order to limit vertical errors due to parasite torques, and secondly in order to ensure satisfactory reliability in view of the fact that the parasite torques can degrade in time depending on environmental conditions.
In this respect, mechanical erectors offer advantages which will be more clearly understood by referring to FIG. 1 in the accompanying drawing, which, while not rigorously representing the phenomena involved, provides a picture thereof which facilitates comprehension.
The parasite torque (PT) due to the suspension is assumed to have a value 1 and the continuous erecting torque (CET) a value 2. The effective erecting torque has a value of 2-1=1.
If one considers a two-pendulum erector which consequently delivers two torque pulses (TP.sub.2) per erector revolution, each being exerted for a quarter-revolution, then the supposedly constant value of these torques imparting the same rate of precession as the continuous erecting torque in question will have to be equal to 3. In other words, the precession of the gyroscope during the time corresponding to one revolution of the mechanical erector is represented by the rectangular areas which lie above the line 1 standing for the value of the parasite torque. Similarly, the precession of the gyroscope with the continuously torquing erector is represented by the rectangular area above the line 1.
Suppose now that the parasite torque increases by 50% (PT+50%), that is, that it assumes the value 1.5. It will be seen that the area which represents the effect of the continuously torquing erector is halved whereas the areas which represent the effect of the mechanical erector are reduced by only one-quarter. Moreover, if the parasite torque were to double in value, then the continuously torquing erector would become completely ineffective, whereas the mechanical erector would still retain half of its effectiveness.
This means that, all other things being equal, a mechanical erector is markedly more reliable than a continuously torquing erector.
It also means that, while retaining a sufficient assurance of reliability, it is possible to accept for mechanical erectors lower precession rates, which as already explained, are beneficial for the quality of the vertical datum in actual utilization conditions.
Of course, as already stated, the actual phenomena encountered do not obey such simple laws, but their qualitative aspects nonetheless conform with these conclusions.
All prior art erector systems with unstable pendulums, particularly the one described in the aforesaid French Pat. No. 1,416,416, and which offer the above advantage, have at least two unstable pendulums. This requirement stems from the fact that when the gyroscope is vertical, the centre of gravity of the pendulums must lie on the axis of the erector in order to obtain a stable vertical datum.
The present invention relates to a rotating mechanical erector for a vertical gyro, essentially characterized in that it includes only one unstable pendulum, yet achieves the same quality for th
REFERENCES:
patent: 2351619 (1944-06-01), Kimball
patent: 2356749 (1944-08-01), Carter
patent: 2480263 (1949-08-01), Raspet
patent: 2504061 (1950-04-01), Alkan
patent: 2572733 (1951-10-01), Konet
patent: 3357263 (1967-12-01), Chombard
patent: 3358515 (1967-12-01), Chombard
Bonck Rodney H.
Societe Francaise (SFENA)
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