Talk:Inertial navigation system

Methodology is confusing

I think the methodology section is very confusing and in it's current form does not add much to the conversation. The diagram is very confusing and unclear exactly what method is being modeled (possibly an information filter?). I think the section should be changed to incorporate some other types of methods such as a high-level diagram of an EKF with a brief explanation and some brief mention of other methods. Mhigger (talk) 18:53, 3 March 2023 (UTC)

History Needs Work

I believe the first gyroscopic guidance systems were developed for underwater torpedos. I've heard these refered to as Obry Units. The Soviets built a boost-glide cruise missile in 1936 that had a gyroscopic guidance system, and of course so did the German V-1 several years later. I believe Goddard had a patent very early in the century for gyroscopic autopilots for airplanes. The idea of putting a gyroscopic guidance sytsem in a rocket was probably first devised by Goddard, he certainly flew a rocket with one in 1932 and probably thought of it many years before that. DonPMitchell (talk) 05:42, 4 August 2008 (UTC)

I deleted the paragraph attributing the Atlas ICBM all inertial guidance system to MIT and Dr. Draper because it is false to fact. Early versions of the Atlas ICBM used a simple three gyro autopilot, supplemented by a doppler radar/rf uplink system provided by Western Electric. The only All Inertial Guidance flown on the Atlas ICBM was provided by the Arma Division of AmBosch Arma. It used a gimbaled platform, a pair of two-degree of freedom gyroscopes, three "vibrating String" accelerometers and a Fixed Program Computer, in contrast to the three single degree of freedom gyros,and Pendulous Integrating Gyroaccelerometers used by MIT. (Modern IGSsystems use none of these obsolete sensing instruments.

As I spent my first 5 years as a Guidance engineer at Cape Canaveral working at test and developement of the Atlas Arma guidance system, I know fact from fiction about this. User: SEIBasaurus.Don (talk) 22:13, 26 August 2009 (UTC)

From AIAA Paper published in 1982 AIAA 82-4075: The previous History did not attribute Atlas guidance to CSDL/MIT, it discussed the initial analytical work. It appears in 2 publications that Arma's work was on the construction (and testing)of the phyical guidance apparatus This book is the most detailed account of guidance history I have seen. It clearly outlines (supported by the AIAA article) that the analytical work (in the design of the mathmatical equations that supported the guidance) was in fact done by MIT/CSDL. There is also solid references that the Atlas guidance contract was given to MIT Intrumentation as referenced here [1]. A most complete discussion of the relationship is provide in this this government reference

...led the [Air Force] management of Atlas to use a two-track strategy for developing an operational guidance system, and “American Bosch Arma Corporation and AC Spark Plug Division of GM, both working in conjunction with Dr.!Draper’s guidance laboratory at MIT, were contracted to develop a parallel, selfcontained all-inertial guidance system.”

Despite the willingness of WDD to fund R&D of inertial systems, this did not mean that the die was cast. First, there was a need to prove that inertial could achieve acceptable levels of performance. Recognizing that an operational test bed would be required, Atlas management decided to use inertial guidance on the shorter range (1,500!nmi) Thor missile concurrently under development with Atlas. As a result, the first several series of Atlas missiles (A through D) were to be guided by radio...

...inertial guidance systems designed by Draper’s research activity would be operationally investigated on Thor. “It was an important contract for Draper’s Instrumentation Laboratory. Finally, their accumulated expertise could be put to work in a major national inertial guidance program.”30 As a result, “Thor went ahead with inertial as the primary system and a radar system as back-up.”31 MIT-designed gyroscopes and accelerometers were produced for Thor by AC Spark Plug, though not without considerable difficulties and an initially low yield of satisfactory instruments. The onboard computer was analog, but an ingenious mathematical scheme called Q-guidance, developed at the Instrumentation Laboratory by Richard H. Battin and J. Halcombe Laning, shifted the bulk of the computational requirements out of the missile.”32

Effectively, the government funded an alliance between a university research organization and a major commercial contractor in which the former designed and developed the technology and the latter produced the product. Moreover, this was done in the context of providing an environment in which ongoing research into inertial guidance could be improved, tested, and deployed for a less ambitious system. The ultimate goal was that this would eventually lead to much more robust capabilities suited for Atlas and follow-on ICBM’s such as Titan and Minuteman.

Hence I am updating History, with a mention to Arma's construction/testing. The paragraphs below will be re-instated and should remain unless there are references to support the fact that Arma developed both the physical, as well as the analytical aspects of the Atlas guidance.

In the early 1950s, the US government wanted to insulate itself against over dependency on the Germany team for military applications. Among the areas that were domestically "developed" was missile guidance. In the early 1950's the MIT Instrumentation Laboratory (later to become the Charles Stark Draper Laboratory, Inc.) was chosen by the Air Force Western Development Division to provide a self-contained guidance system backup to Convair in San Diego for the new Atlas intercontinental ballistic missile [2][ http://www.history.navy.mil/colloquia/cch9c.html. (Construction and testing were completed by Arma Division of AmBosch Arma). The technical monitor for the MIT task was a young engineer named Jim Fletcher who later served as the NASA Administrator. The Atlas guidance system was to be a combination of an on-board autonomous system, and a ground-based tracking and command system. This was the beginning of a philosophic controversy, which, in some areas, remains unresolved. The self-contained system finally prevailed in ballistic missile applications for obvious reasons. In space exploration, a mixture of the two remains.

--Xs4-guy (talk) 00:06, 6 November 2009 (UTC)

References

Tyop for cross-product?

"the vector cross product (v, xdv, /dt)" - should this be written as (v × dv/dt) instead? Bungo77 (talk) 08:07, 28 May 2009 (UTC)

No external reference?

In the introduction it says that it measures velocity without using an external reference. How this can be correct? The velocity of any point of a rigid body respect to a frame that moves with the rigid body is always zero. How can you say that a velocity can be measured without external references? This would mean that a body has an absolute state of motion, which since Galileo, is not considered true. I am sure the information given is correct but it may be biased by the jargon of the community. Probably the without external reference is something like, respect to the stars or respect to a reference point fixed at ground (like the base or airport), but is assumed known and hence not mentioned.Kakila —Preceding undated comment added 09:38, 29 September 2009 (UTC). The Inertial System Proper does not measure velocity. It has an added device/system to measure acceleration (the integral is velocity - Newtons Fluxion equation. Ed —Preceding unsigned comment added by 98.148.249.104 (talk) 15:59, 5 October 2010 (UTC)

"... without the need for external references" refers to without the need for some kind of external signal (e.g. GPS, VOR, DME). Pure inertial navigation systems measure acceleration and attitude using only onboard inertial sensors. These measurements are integrated to produce velocity and position. No external signals are used. In practice, most systems that use inertial sensors also incorporate external signals. Bottom line - the statement is correct. Dpdannemiller (talk) 03:29, 19 December 2011 (UTC)

Ships Inertial Navigation System (SINS)

Can someone add a section with the above title. This system was introduced by the US Navy in the 1950's and could provide an insight into the decvelopment of IN systems.Petebutt (talk) 20:06, 13 August 2010 (UTC)

Gimballed gyrostabilized platforms )

In this paragraph, shouldn't be precised that the twin gyroscopes must rotate in contrary motion in order to cancel precession ? 78.227.102.29 (talk) 12:36, 17 October 2010 (UTC) nickgreg

Added a reference to my LN-3 Inertial Navigation System article, which was one of the first (1962) 4-gimbal inertial navigators in a high performance jet. Klu Andre, 24 dec 2010. — Preceding unsigned comment added by Klu andre (talk • contribs) 08:20, 24 December 2010 (UTC)

TIMU (Timing & Inertial Measurement Unit) sensors

DARPA's Microsystems Technology Office( MTO) department is working on a Micro-PNT ("Micro-Technology for Positioning, Navigation and Timing") program to design "TIMU" ("Timing & Inertial Measurement Unit") chips that does absolute position tracking on a single chip without GPS aided navigation.

Micro-PNT adds integrates a highly-accurate master timing clock integrated into a IMU (Inertial Measurement Unit) chip, making it a "TIMU" ("Timing & Inertial Measurement Unit") chip. So these TIMU chips for Micro-PNT have integrated 3-axis gyroscope, 3-axis accelerometer, and 3-axis magnetometer, and together with the integrated highly-accurate master timing clock it simultaneous measure the motion tracked and combines that with timing from the synchronized clock, and with sensor fusion it makes a single chip that does absolute position tracking, all without external transmitters/transceivers.

Somebody over DARPA has gotten very good at copy/pasting this same two paragraphs ALL OVER Wikipedia pages (IMU, inertial navigation, etc.). If you guys want to promote your work, at least fix the dead links you are plastering everywhere! — Preceding unsigned comment added by 76.120.124.223 (talk) 06:16, 7 November 2015 (UTC)

References

method,not methodology

Methodology is the study of various ways to achieve an end,a method is the way then used.https://en.wikipedia.org/wiki/Methodology AptitudeDesign (talk) 01:57, 20 April 2014 (UTC)

Error units

The section "Error" says that a good system will have an error on the order of 0.6 nautical miles per hour. But since position depends on a double integration over time, the error should have units of miles per hour per hour. The error in velocity should be proportional to time, and the error in position proportional to time squared. (I'm talkin' about systematic error, not random error. If we talk just about random, Gaussian error, then the error in velocity would be proportional to the square root of time, and the error in position proportional to time to the power 3/2.) Eric Kvaalen (talk) 16:29, 28 January 2017 (UTC)

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Mobile Robots?

Curious why mobile robots are specifically mentioned in the first section of this article... Also a bit curious as to why there is a citation needed after the list of vehicles that certainly use inertial navigation systems (ships, submarines and aircraft use these systems by nature). Mobile robots seem like a more specialized case and does not seem necessary to be mentioned at all. If no one else has anything to add after a few days I will change the wording in this article. NedTown5000 (talk) 02:44, 29 July 2020 (UTC)