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Subject: 
Re: Inertial guidance
Newsgroups: 
lugnet.robotics
Date: 
Sat, 12 Jan 2002 18:28:23 GMT
Viewed: 
1367 times
  
In lugnet.robotics, sjbaker1@airmail.net writes:
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!

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 speeds.  Hmm...

--Ian



Message has 1 Reply:
  Re: Inertial guidance
 
I am developing a two axis acceleration sensor that is RCX compatible. Unfortunately, that by itself is not sufficient for inertial navigation in a fixed plane. (i.e. a robot that stays on the floor) A fully inertial system would need a rotational (...) (23 years ago, 12-Jan-02, to lugnet.robotics)

Message is in Reply To:
  Re: Inertial guidance
 
(...) 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 (...) (23 years ago, 12-Jan-02, to lugnet.robotics)

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