Subject:
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Re: Inertial guidance
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Newsgroups:
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lugnet.robotics
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Date:
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Sat, 12 Jan 2002 17:09:04 GMT
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Original-From:
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Steve Baker <sjbaker1@airmail.net[SayNoToSpam]>
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Reply-To:
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SJBAKER1@AIRMAILspamcake.NET
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Viewed:
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1941 times
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Ian Warfield wrote:
>
> In lugnet.robotics, Pete Sevcik writes:
> > Has anyone tried to do inertial guidance with the RCX ?
>
> Uh, how do you mean? Inertia pretty much guides itself, unless you want to
> abolish Newton's First Law...?
The term "inertial guidance" refers to a navigational technique that involves
carefully measuring the rotational and translational accelleration of the
vehicle, then integrating that to derive the velocity and integrating *that*
to get the vehicles position.
The big problem with inertial guidance is precision. If you make even a
tiny error in measuring accelleration, that will add up over time to create
a larger error in your velocity - which in turn adds up over time to make
for huge positional errors.
It's generally useful to use inertial navigation only when you can
periodically reset the error by reference to some absolute positioning
cue. It's not generally a good idea to use inertial guidance on systems
that can be the victims of impact forces - since those induce very large
accellerations for very short amounts of time - those are almost impossible
to measure with enough precision. Hence, the technique is mostly used on
aircraft, missiles and spacecraft (where you don't expect to hit anything!)
You also generally need six sensors in order to measure the accellerations
in all six degrees of freedom - that's not gonna be nice for an RCX!
----------------------------- Steve Baker -------------------------------
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Message has 2 Replies:
 | | Re: Inertial guidance
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| (...) Actually, i think you could use TWO rotation sensors because the rotation sensors work in both directions, and Lego generally doesnt go up and down (but it might if you had some sort of maze with ramps). (23 years ago, 12-Jan-02, to lugnet.robotics)
| | | Re: Inertial guidance
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| (...) Ah, I see. Thanks for your explanation. How would one make inertial sensors for the RCX anyway? I suppose you could rig a plumb bob to a rotation sensor - but as you had already pointed out, rotation sensors are inaccurate at low rotation (...) (23 years ago, 12-Jan-02, to lugnet.robotics)
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Message is in Reply To:
| | Re: Inertial guidance
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| (...) Uh, how do you mean? Inertia pretty much guides itself, unless you want to abolish Newton's First Law...? --Ian (23 years ago, 12-Jan-02, to lugnet.robotics)
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