Talk:Gyrocompass

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im doing an assignment for maths on the gyrocompass. what is the history of this instrument? why was is developed? have there been any similar instruments before or after this one? what is it used for? how do you use the instrument? what are its limitations? what cant it do? what possible errors of measurement can it produce? what are some of the implications of these errors?

if anyone can help me by answering any of these questions id greatly appreciate it! thankyou so much for your time.

krystal.

"ferrous metals"
Rather than go far afield into discussions of paramagnetic and diamagnetic materials I removed the technically incomplete "nonferrous wires with current" digression. —Preceding unsigned comment added by 67.101.101.98 (talk) 22:51, 3 October 2008 (UTC)

"North Star"
I'm no where close to an expert on gyrocompasses but I'm questioning the article's use of the term "north star" repeatedly. As in "This friction force caused by the fluid results in a torque acting on the axis, causing the axis to turn in a direction orthogonal to the torque (that is, to precess) toward true North (to the North star)." I had always thought that the notion of "true north" being in the general direction of the North star was a coincidence. In a few thousand years true north and the North star will diverge. Shouldn't all of the uses of the "North star" in this article be replaced by something more accurate and less coincidental?

24.159.110.25 23:55, 25 December 2006 (UTC) Brad Dixon
 * Like North Celestial Pole?

"Crucial ingredient"
I don't really feel I can change the article itself but I do have a slight issue with the wording of one part. I have done a fair bit of work at university on the gyrocompass, and I think that to cite friction as the "crucial ingredient" is misleading. The actual "crucial ingredient" is the combination of an applied torque and the rotation it causes (it can also be a rotation and a resulting torque, the two are both linked). Friction may be one method of applying this torque but I have not yet come across it.

In its simplest and most effective form, a gyrocompass is a gyroscope in which the gimbals (or mountings) are modified to force the rotor axis to remain horizontal relative to the earth's surface. The components of rotation caused by the spin of the earth mean that the rotor must align itself with the true meridian in order to obey the law of conservation of angular momentum.

Other, more practical gyrocompasses use gravity to keep the rotor horizontal/apply the torque. This is necessary on a pitching and rolling ship, where horizontal is not the same as the floor!

James

Nosrednax 15:54, 28 September 2005 (UTC)


 * I didn't know anything about gyrocompasses before reading this article, but I've tried anyway to apply James's advice to the article. Feel free to correct me if I've done so incorrectly, and please add sources if you know of any.  --Allen 05:59, 9 October 2006 (UTC)

Forgot to add the reason for my change.
Changed the link of Magnetic North to http://en.wikipedia.org/wiki/Magnetic_North_Pole#North_Geomagnetic_Pole because it was instead linking to an album by Hopefall: http://en.wikipedia.org/wiki/Magnetic_North.--M-w-b 09:39, 20 July 2007 (UTC)

Satellites and History
It migth also be mentioned the gyrocompass is used is satellite stabilization. In combination with a horizion sensor, this is how early American and Soviet spy satelites maintained 3-axis orientation.

With regard to history, the discussion of Kaempfe vs. Sperry seems to imply that Sperry just stole someone's ideas. Kaempfe was an art major who stumbled on the gyrocompass concept while trying to convince the navy to fund a submarine expedition. Sperry did independant work on gyroscopes, and his engineers dominated the research and development of many gyroscopic-based servomechanisms over a period of years (ship stabilizers, autopilots, etc). What I'm saying is, Kaempfe was first, but Sperry (and Minorsky and others) were really more important, not just someone who stole an idea from someone else. A good book to look at is Bennett's history of control engineering. DonPMitchell (talk) 22:32, 19 May 2008 (UTC)


 * This article is WAY too hard to understand. If you don't know how a gyroscopic compass works before you read it, you wn'

t know afterwards either. 80.169.162.100 (talk) 14:31, 10 February 2010 (UTC)

Factual error, vandalism or correct?
Regarding the statement in one of the paras: "Since the operation of a gyrocompass crucially depends on the rotation of the Earth, it won't function correctly if the vessel it is mounted on is moving fast in an east to west direction.".....

Either I'm missing something or I fell asleep during Physics 101!
 * 1) Gyros DON'T depend on the rotation of the Earth A gyro's most basic function (fixed reference in space) doesn't depend on the rotation of the Earth! (see elaboration below) They never have. Their operating principles are wholly derived from the classical, universal laws of physics (as per Gyroscope);
 * 2) if the spin axis of a gyro compass is set to point to the star Rigel, it will continually point to Rigel no matter how the gyro's mount turns, tumbles or translates, provided there are no external forces applied to the gyro disc (caveat: I'm fuzzy on the implications of near-light speed travel, but I don't think that would impact the classical laws affecting gyros -please update me on that);
 * 3) gyro compasses have long been used in commercial jetliners, military and commercial supersonic aircraft, and spacecraft.  I don't believe any of them have gotten lost travelling in a westerly direction (or any direction for that matter as long as the navigators/flight directors didn't fall asleep at the switch or break down...).

So please update me if I've missed (or forgotten) something from class, and forgive me for excising the statement from the article and labeling it as sneaky vandalism. I suspect vandalism as the reason for the statement (rather than a simple factual error), as its author's has likely concluded that most people know that the Earth rotates from west to east, and that moving quickly from east to west would tend to cancel out a vessel's angular rotation relative to a fixed point in outer space, thus providing a 'scientific' rational for the statement. Or at least that's my best guess for the vandal's M.O. (see comments below on why I've changed my view on this -hz)  Best: HarryZilber (talk) 12:58, 27 August 2010 (UTC)

Supplementary note: Here's a good solid page of theory on gyro compasses, in a reference work called American Practical Navigator, 2002, pg.93, by Nathaniel Bowditch (ISBN 9780939837540). A quick scan doesn't bring up anything supporting the original statement. However a separate review of a gyrocompass's sundry features shows that its 'automatic north-seeking' function is dependent of the earth's rotation (by means of gyroscopic procession, if the spin axis is pointing other than true north). Thus the original sentence can be correctly modified to read:
 * "Since the operation of a gyrocompass's automatic north-seeking function can depend on the rotation of the Earth, it won't orient itself correctly to true north if the platform its mounted on is moving fast in an east to west direction, thus negating the Earth's rotation. However, many gyrocompass models can be manually aligned with true north as is commonly done."

...as I've performed numerous times in the past. Comments? HarryZilber (talk) 18:02, 27 August 2010 (UTC)


 * Lacking other comments, I've rewritten and restored to the article the previously removed sentence, changed to now read:
 * "Since the operation of a gyrocompass's automatic north-seeking function depends on the rotation of the Earth to deflect the compass via gyroscopic precession, it will not orient itself correctly to true north if the vessel its mounted on is moving very fast in an east to west direction, thus negating the Earth's rotation. However, many aviation models, called directional gyros, can be quickly aligned manually to north as is commonly done on aircraft flights."
 * HarryZilber (talk) 14:10, 29 August 2010 (UTC)
 * Harry, not saying anything about your Physics 101, you do mistake a gyroscope with a gyrocompass. The first one operates on gyroscopic effect and the second one operates on gyroscopic precession effect. The first one has three axes free, and the second has two axes free + one axis fixed. The first one operates in outer space, the second operates (properly) only on a celestial body that rotates (otherwise it becomes just a heavy/overcomplicated gyroscope). The first is most common on aircraft, the second on ships. Your scan of Bowditch was indeed quick, because most of it is plainly stated there - including the fact that rotation of Earth is required for operation ("gyrocompass depends upon four natural phenomena: ..."). I've edited the article accordingly. --Kubanczyk (talk) 20:38, 1 November 2011 (UTC)


 * Thanks for improving the article. Best: HarryZilber (talk) 22:32, 1 November 2011 (UTC)

History - Hermann Anschütz-Kaempfe
Should we not include at least a short reference to Hermann Anschütz-Kaempfe and his 1904 patent on the theoretical workings of a gyrocompass? I strongly feel that the current article is woefully incomplete without mentioning that. (Cyberroach (talk) 14:12, 25 January 2011 (UTC))


 * Hi Cyberroach: yes, a subsection on his works would be commendable. There are currently Wikipedia articles on Mr. Anschütz-Kaempfe in six languages, but the English article is a very brief stub that only mentions gyrocompasses in passing. Can you provide the explanation of his works relative to this device?  Best: HarryZilber (talk) 20:13, 25 January 2011 (UTC)


 * Anschütz invent the world first self north adjusting gyrocompass. It's maybe for interest Sperry infringe the Anschütz patent. Sperry lost 1915 the patent lawsuit. The lawsuit consultant was Albert Einstein and Anschütz win 1915 this lawsuit.

--HDP (talk) 11:03, 26 January 2011 (UTC)


 * Fixed. --Kubanczyk (talk) 20:39, 1 November 2011 (UTC)

Mathematical description of a gyrocompass
I think a mathematical description of a gyrocompass is useful, for students and for general people. I tried to add a section, but it was erased at once without discussing even this topic. — Preceding unsigned comment added by Antoniuspisa (talk • contribs) 05:27, 23 November 2013 (UTC)

The gyrocompass wiki page says that "aircraft commonly use heading indicators or directional gyros, which are not gyrocompasses and do not position themselves to north via precession, but are periodically aligned manually to true north". The wiki page for Heading_indicator says that they are aligned manually to magnetic north. I don't know enough about aircraft to know which is correct. Adaviel (talk) 23:20, 13 November 2014 (UTC)

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Multiple problems with "Mathematical model" section
I don't want to make large-scale changes here without feedback or discussion.

"We consider a gyrocompass as a gyroscope which is free to rotate about one of its symmetry axes"
the WP definition of a Gyroscope is a spinning disk with two gimbals. I think we should cleary distinguish between the spinning disk (the rotor) and a gyroscope mechanism (with two gimbals). The expression "rotate about one of its symmetry axes" appears many times, couldn't we just say rotor spin axis as per Gyroscope.

"Therefore there are two independent local rotations"

 * Confusing! Is this the two gimbals of a Gyroscope or is it the spin axis and one rotation about the local vertical?

"We establish cartesian coordinates (X1,Y1,Z1)"


 * cartesian should be capitalised
 * it's not clear what X1,Y1,Z1 are. Later it looks like these are used like elements of a point coordinate vector.  We should talk about establishing a local coordinate frame, often written as {1}.

"First time-dependent rotation"

 * (X1,Y1,Z1) looks like the coordinate vector for a point expressed with respect to frame {1} which is being transformed to a coordinate vector with respect to frame {2}.
 * this is simply a rigid body rotation from frame {1} to frame {2}. It is written as a point transformation which is the transpose of the rigid body transformation.  I know there are strong feelings about whether to use rigid-body transformations or point transformations, I prefer the former, but at the very least the article should clearly describe what it is using.

"Fourth time-dependent rotation"

 * Is this the orientation of the rotor's spin axis with respect to true north (TN)?
 * Should state explicitly that the x-axis of frame {6} points to TN.

"Last time-dependent rotation"

 * "The last rotation is a rotation on the axis", normally we speak of a rotation being about or around an axis, not on an axis.
 * Is this the rotation of the rotor about its axis? ie. is $$\dot{\psi}$$ the angular velocity of the robot disk.  For a gyrocompass we assume its axis is always in the horizontal plane?  Why is there no t in this equation as there is for the first time-dependent rotation?
 * "The last rotation is a rotation on the axis", be clearer about where this new frame {7} is located. It looks like it is attached to the barycentre of the spinning rotor disk.

"Dynamics of the system

 * $$\vec{\omega}$$ is not actually defined. From the definition of the kinetic energy it must be the total angular velocity of the rotor due to rotor and Earth rotation.
 * " On the other hand, t T he tensor of the rotor's inertia is given by"
 * The big expression for $$\vec{\omega}$$ has a &times; symbol which is confusing, there is no cross product here, it is matrix-matrix multiplication.
 * There should be an explicit mention of why the translation from frame {4} to {5} is ignored.
 * When the expression for $$\ddot{\alpha}$$ is discussed it should be in the context of an oscillation about zero (ie. pointing to TN).
 * "is the part of the Lagrangian responsible for the dynamics of the system of the rotor axis pointing direction &alpha; ."
 * "where the angular velocity frequency (in radians) of this harmonic motion of the rotor axis of symmetry of the gyrocompass about the north-south line is given by"

Please define phi.
This angle is undefined in the section on second and third fixed angles of rotation. Burressd (talk) 15:24, 24 March 2023 (UTC)