Optics: measuring and testing – By dispersed light spectroscopy – Utilizing a spectrometer
Patent
1984-07-05
1987-02-17
McGraw, Vincent P.
Optics: measuring and testing
By dispersed light spectroscopy
Utilizing a spectrometer
G01C 1964
Patent
active
046435743
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a method for determining the angular velocities .OMEGA..sub.I, .OMEGA..sub.II and/or .OMEGA..sub.III about at least two axes I, II and/or III of a preferably rectangular coordinate system. These axes may be, for example, the axles of a vehicle.
It is known to measure the angular velocities about two or even three axes that are perpendicular to one another by utilizing correspondingly placed gyros. Such a measuring arrangement is expensive.
It is the object of the invention to reduce the expenditures for measuring at least two angular velocities about mutually perpendicular axes.
This is accomplished in that a gyro (e.g. a laser gyro) which does not offer any resistance to rotation about any desired axis is rotated at a known angular velocity .omega..sub.o having the known components .omega..sub.oI, .omega..sub.oII and .omega..sub.oIII about an auxiliary axis whose orientation in the coordinate system is defined by the angles .phi. and .theta., with .phi. being the angle between the first axis and the projection of this auxiliary axis of rotation in the plane defined by the first and second axis and .theta. is the angle between the auxiliary axis of rotation and this projection. The input axis of the gyro is inclined toward the auxiliary axis by an angle of 90[.degree.]-.delta. and the value for .OMEGA. is measured at angular values .alpha.=.omega..sub.o t, at which components of the term (.phi.), (.theta.), (.delta.), (sin .omega..sub.o t) and (cos .omega..sub.o t)] values for .OMEGA..sub.I, .OMEGA..sub.II and/or .OMEGA..sub.III being calculated from the resulting equations.
The following term results for the output signal .OMEGA. of the gyro: ##EQU1##
Pursuant to the first feature of the solution according to the invention, a gyro is employed which does not offer any resistance to the required rotation; a mechanical gyro cannot be used here. The above stated teaching permits the determination of only two or also three angular velocities .OMEGA..sub.I, .OMEGA..sub.II and/or .OMEGA..sub.III. To simplify the calculation, the auxiliary axis of rotation is placed advantageously into one axis, e.g. into the third axis; then there will be no components of .omega..sub.o about the other axes. Since .phi. and .theta. are zero, Equation (1) above is simplified to: .delta. sin .omega..sub.o t+(.OMEGA..sub.III +.omega..sub.oIII) sin .delta.(2)
It can be seen that with this arrangement it is possible to determine all three components .OMEGA..sub.I to .OMEGA..sub.III by measuring .OMEGA. at cos .omega..sub.o t.sub.1 =0 and sin .omega..sub.o t.sub.2 =0 and a third value of .omega..sub.t (.omega..sub.o t.sub.3), at which the sine or cosine of .omega.t.sub.3 becomes 0. .delta. is constant. If .delta. is made to equal zero, the last term can be omitted and .omega..sub.I and .omega..sub.II can be determined by measuring .OMEGA. at two angles .alpha. which differ by 90.degree. (or an odd multiple thereof).
Preferably, the angular velocity .omega..sub.o is selected at such magnitude that it is greater than the greatest possible angular velocities to be determined. Only then is it assured that the .OMEGA. values determined successively at various angles of .alpha. or possibly .delta. originate from the same angular velocity.
Thus, .omega..sub.o will be selected depending on the case at hand. For use on ships, there will occur practically no angular velocities .OMEGA. greater than a few radians/sec. In this case, a value of, e.g., 10 revolutions per second is sufficient for .omega..sub.o. For use in land vehicles, a greater .omega..sub.o will have to be selected, e.g. 30 to 100 revolutions per second.
Although it is actually sufficient to swing the gyro back and forth over only a sufficient angular range at .omega..sub.o, continuous rotation will generally be preferred. If .omega..sub.o is constant over the entire range of rotation, the components resulting therefrom can also be calculated and are constant. If necessary, .omega..sub.o must also be measured by measuring the time required for one revolutio
REFERENCES:
patent: 4017187 (1977-04-01), Schwartz
patent: 4243324 (1981-01-01), Friedland
patent: 4407583 (1983-10-01), Simms
McGraw Vincent P.
Teldix GmbH
Turner S. A.
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