🚀 go-pugleaf

In article <Bx0rxx.5Mn@zoo.toronto.edu>, henry@zoo.toronto.edu (Henry Spencer) writes:
> In article <92301.100823U60901@uicvm.uic.edu> Andrea Sterbini <U60901@uicvm.uic.edu> writes:
> >I'm searching for a portable inertial platform, that can record the path and
> >thath can be connected to a computer for data analysis.
> 
> You left out the crucial requirements:  how accurate does it have to be,
> and for how long?
> 
> The fundamental problem of inertial guidance is that even the slightest
> error in sensing direction is magnified into large position errors by
> the two integration steps (acceleration -> velocity, velocity -> position).
> This results in a fundamental requirement for very-high-quality gyroscopes.
> Accelerometers are the easy part.

...short discussion about costs omitted....

	You also have to worry about the compounding of the errors as
a function of time.  Drift rates for "cheap" sensors can be 0.1 degree
per minute. At those kind of rates, it doesn't take long to get lost.
	In typical airborne and surface ship inertial systems, the
position solution gets updated from some external reference (GPS,
Loran, Transit, etc....)

	As for price, I agree with Henry, if you have to ask, you
aren't in the right league.  The other price you have to consider is
the cost (per hour or year) to keep the thing running. Mechanical
gyros have very finite lifetimes. Ring laser gyros are starting to
become available in aircraft intertial nav systems.

One vendor of gyros is:
	Humprhey Inc
	9212 Balboa Av.
	San Diego, CA   92123

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Dale Chayes
Senior Staff Associate
Lamont-Doherty Geological Observatory of Columbia University