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What does a Accelerometer do? What instrument can I use

What does a Accelerometer do? What instrument can I use - Physics Forum

What does a Accelerometer do? What instrument can I use - Physics Forum. Discuss and ask physics questions, kinematics and other physics problems.


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  #1  
Old 02-23-2005, 06:27 AM
Sea Squid
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Default What does a Accelerometer do? What instrument can I use



to measure the acceleration of my robot without tapping at the wheels
and motors? Basically I need something that is standalone and can give
my CPU a digital reading of the speed and acceleration, and direction
with respect to the North.

Thanks.



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  #2  
Old 02-23-2005, 06:40 AM
Sea Squid
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Default What does a Accelerometer do? What instrument can I use

Plus, I need my accelerometer to be more than one dimensional, meaning
when it should solve the problem of acceleration, side tilting, road humps,
etc(is this requirement called "omnidirectional"?).






"Sea Squid" <[Only registered users see links. ]> wrote in message
news:421c20f7$[Only registered users see links. ].sg...


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  #3  
Old 02-23-2005, 08:37 AM
CWatters
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Default What does a Accelerometer do? What instrument can I use


"Sea Squid" <[Only registered users see links. ]> wrote in message
news:421c23ff$[Only registered users see links. ].sg...
humps,

Can you explain what the CPU will do with the data?


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  #4  
Old 02-23-2005, 08:51 AM
Franz Heymann
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Default What does a Accelerometer do? What instrument can I use


"Sea Squid" <[Only registered users see links. ]> wrote in message
news:421c23ff$[Only registered users see links. ].sg...
meaning
humps,

At first sight it looks to me as if you should not be attempting to
build such a fancy robot. You do not appear to have enough
engineering background.

--
Franz
"The great tragedy of science -- the slaying of a beautiful hypothesis
by an ugly fact."
T.H. Huxley


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  #5  
Old 02-23-2005, 11:37 AM
Tom Potter
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Default What does a Accelerometer do? What instrument can I use


"Sea Squid" <[Only registered users see links. ]> wrote in message
news:421c23ff$[Only registered users see links. ].sg...

Do a Google search on "rate gyro" and robot.

--
Tom Potter
[Only registered users see links. ]
[Only registered users see links. ]


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  #6  
Old 02-23-2005, 01:30 PM
Androcles
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Default What does a Accelerometer do? What instrument can I use


"Sea Squid" <[Only registered users see links. ]> wrote in message
news:421c20f7$[Only registered users see links. ].sg...
[Only registered users see links. ]

[Only registered users see links. ]

Androcles.


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  #7  
Old 02-23-2005, 01:33 PM
Ken Kubos
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Default What does a Accelerometer do? What instrument can I use

Check out: [Only registered users see links. ]

--
Ken

"Buddhism elucidates why we are sentient."

"Sea Squid" <[Only registered users see links. ]> wrote in message
news:421c20f7$[Only registered users see links. ].sg...
| to measure the acceleration of my robot without tapping at the wheels
| and motors? Basically I need something that is standalone and can give
| my CPU a digital reading of the speed and acceleration, and direction
| with respect to the North.
|
| Thanks.
|
|
|


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  #8  
Old 02-23-2005, 01:44 PM
Andy Resnick
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Default What does a Accelerometer do? What instrument can I use

Sea Squid wrote:



[Only registered users see links. ]

--
Andrew Resnick, Ph.D.
Department of Physiology and Biophysics
Case Western Reserve University
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  #9  
Old 02-23-2005, 03:01 PM
Randy Poe
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Default What does a Accelerometer do? What instrument can I use


Sea Squid wrote:
give

The name for what you're trying to do (determine position
based on speed and acceleration measurements) is called inertial
navigation. Androcles posted a link with that title.

You start from a known fix and then measurements of speed
and acceleration can be used to plot out your current position.
However, this is of limited accuracy and the errors grow with
time. Aircraft and ships use inertial navigation, but they need
to periodically get a fix on a known location in order to correct
their estimates of position.

You asked about measuring compass bearing. My first thought
there was that it would be nice if there was such a thing
as a digital compass which your robot could use directly to
sense direction. Lo and behold, typing "digital compass"
into Google gave me products that do this, e.g.

[Only registered users see links. ]

I suspect those guys will also have suggestions for your
other navigation needs.

- Randy

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  #10  
Old 02-23-2005, 04:03 PM
Uncle Al
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Default What does a Accelerometer do? What instrument can I use

Androcles wrote:
[snip]


<http://www.google.com/search?q=Androcles+fumble+site%3Ausers.pandora.be>
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/EnergyConservation.html>
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/HopeThatHelps.html>
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/PrizeYours.html>
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/CoverUp.html>
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/GDefence.html>
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/OneDim.html>
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/Gullible.html>
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/RelativityCancer.html>
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/Androrgasm.html>
Androcyst is a spewing psychotic idiot troll.


Why are you having so much trouble with basic algebra?

Let L = distance between Sam and Joe, as measured in the stationary
frame.
Let L' = distance between Sam and Joe, as measured in the moving
frame.
Let v = speed of Sam and Joe, as measured in the stationary frame
(with Joe in front of Sam).

Let L_1 = distance light travels in going from Sam to Joe, as
measured in the stationary frame.
Let L_1' = distance light travels in going from Sam to Joe, as
measured in the moving frame.
Let T_1 = time light travels in going from Sam to Joe, as measured in
the stationary frame.
Let T_1' = time light travels in going from Sam to Joe, as measured
in the moving frame.

Let L_2 = distance light travels in going from Joe to Sam, as
measured in the stationary frame.
Let L_2' = distance light travels in going from Joe to Sam, as
measured in the moving frame.
Let T_2 = time light travels in going from Joe to Sam, as measured in
the stationary frame.
Let T_2' = time light travels in going from Joe to Sam, as measured
in the moving frame.

What people are saying to you is that

1) L_1 = cL/(c-v)
2) L_1/T_1 = c
3) L_1' = L'
4) L_1'/T_1' = c
5) L_2 = cL/(c+v)
6) L_2/T_2 = c
7) L_2' = L'
8) L_2'/T_2' = c

So

L_1 is *not* equal to L_2
L_1 is *not* equal to L
L_1 is *not* equal to L'
L_1 is *not* equal to L_1'
L_2 is *not* equal to L
L_2 is *not* equal to L'
L_2 is *not* equal to L_2'
T_1 is *not* equal to T_2
T_1 is *not* equal to L/c
T_1 is *not* equal to L'/c
T_1 is *not* equal to T_1'
T_2 is *not* equal to L/c
T_2 is *not* equal to L'/c
T_2 is *not* equal to T_2'

On the other hand,

L_1' is equal to L_2'
L_1' is equal to L'
L_2' is equal to L'
T_1' is equal to T_2'
T_1' is equal to L'/c
T_2' is equal to L'/c

Is there yet another way for you to misunderstand?

Einstein:
½[tau(0,0,0,t)+tau(0,0,0,t+x'/(c-v)+x'/(c+v))] =
tau(x',0,0,t+x'/(c-v))

Taking a = x, b = t + x'/(c-v), the functional equation above becomes:
tau(0,0,0,b-a/(c-v)) + tau(0,0,0,b+a/(c+v)) = 2 tau(a,0,0,b).
Defining the function F(k) = 2 tau(0,0,0,k), it then follows that
tau(a,0,0,b) = F(b-a/(c-v)) + F(b+a/(c+v)).
Conversely, taking a = 0 in the equation above, it follows that
tau(0,0,0,b) = F(b) + F(b) = 2F(b).
Therefore, the general solution to the functional equation above is:
tau(a,0,0,b) = F(b-a/(c-v)) + F(b+a/(c+v))
where F is otherwise arbitrary.

(Further restrictions cited in the paper then narrow down the function
F(x); this also shows that the assumption in the paper of
differentiability is entirely superfluous. The derivation above
proceeds without any assumption about tau being differentiable or even
continuous.)

Thus, going back to Einstein's notation with x' = x - vt, it follows
that
tau(x-vt,0,0,t) = F((ct-x)/(c-v)) + F((ct+x)/(c-v))
which shows that the natural coordinates that enter into play are ct-x
and ct+x.

In terms of these the Lorentz transformation simplifies substantially:
ct-x -> sqrt((c+v)/(c-v)) (ct-x)
ct+x -> sqrt((c-v)/(c+v)) (ct+x)
involving, respectively, a blue shift and red shift factor and
directly representing the Relativistic Doppler effect.

If two Lorentz transformation are done along the x axis at velocities
v1 and v2 respectively, then the factors would multiple:
sqrt((c+v1)/(c-v1)) sqrt((c+v2)/(c-v2))
which reduces to a Lorentz transform with a velocity v given by:
sqrt((c+v)/(c-v)) = sqrt((c+v1)/(c-v1)) sqrt((c+v2)/(c-v2))
Solving this for v, you get:
v = (v1 + v2)/(1 + v1 v2/c^2)

So the velocity addition rule becomes the addition rule for the
"rapidity":
u = c/2 ln((c+v)/(c-v))
with
u = u1 + u2.

Rapidity and velocity are virtually identical. For a vessel going at
v= 3km/second,
|v - u| ~~ 6 microns/second.

Therefore, velocities (redefined as rapidities) add as usual in
Relativity, as well as in Newtonian physics.


Hey idiot Androcles,

<http://www.google.com/search?q=Androcles+fumble+site%3Ausers.pandora.be>

reposting the same idiot drool that has been so thoroughly, utterly
publicly discredited by those who can do math (e.g., Randy Poe, in
disgustingly punctilious counterpoint) merely demonstrates what an
intractible idiot you are.

Empirical physical reality casts the only votes that count. Your
idiot spew is falsified by trivial empirical observation. You are a
psychotic ineducable idiot.

Where are your citations, idiot Androcles? Where are your literature
references, idiot Androcles? Where is your empirical observational
support, idiot Androcles? You drown in explicit empirical
falsfification, idiot Androcles. Your ignorance, incompetence, and
psychosis are not of interest to the world at large. Quite the
contrary. You are not even an interesting laughingstock.

<http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/airtim.html>
Hafele-Keating experiment. You are ****ed, idiot Androcles.

Nature 425 374 (2003)
<http://relativity.livingreviews.org/Articles/lrr-2003-1/>
[Only registered users see links. ]
<http://www.public.asu.edu/~rjjacob/Lecture16.pdf>
Relativity in the GPS system. You are ****ed, idiot Androcles.

<http://relativity.livingreviews.org/Articles/lrr-2003-1/>
[Only registered users see links. ]
<http://www.weburbia.demon.co.uk/physics/experiments.html>
Experimental constraints on General Relativity. You are ****ed,
idiot Androcles.

Science 303(5661) 1143;1153 (2004)
[Only registered users see links. ]
[Only registered users see links. ]
Deeply relativistic neutron star binaries. You are ****ed, idiot
Androcles.

Physics Today 57(7) 40 (2004)
[Only registered users see links. ]
No aether. You are ****ed, idiot Androcles.

[Only registered users see links. ]
[Only registered users see links. ]
No Lorentz violation. You are ****ed, idiot Androcles.

<http://math.ucr.edu/home/baez/RelWWW/tests.html>
Mathematics of gravitation. You are ****ed, idiot Androcles.
[Only registered users see links. ]
You are ****ed, idiot Androcles.
[Only registered users see links. ]
You are ****ed, idiot Androcles.
<http://insti.physics.sunysb.edu/~siegel/Fields2.pdf>
You are ****ed, idiot Androcles.

Idiot Androcles is a eunuch in a brothel, a capon in a henhouse, a
steer amidst cows; a stot, a gelding, a gelt, a havier, a gib, a
lapin, a seg, a hog, a wether... a butt-****ed psychotic idiot spewing
in a science newsgroup.

Androcyst and logs:
<[Only registered users see links. ]
Androcyst and vectors:
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/IdiotVectors.html>
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/AndroVec.html>
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/VectorLength.html>
<[Only registered users see links. ]
Androcyst and limits:
<[Only registered users see links. ]
Androcyst and equations:
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/Pythagoras2.html>
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/SetSolve2.html>
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/Persuasive.html>
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/AndroDistri.html>
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/Pythagoras.html>
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/ToothlessBite.html>
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/Competent.html>
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/UseTrans.html>
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/Sheesh.html>
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/SetSolve.html>
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/DivZero.html>
<[Only registered users see links. ]
Androcyst and square roots:
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/STILL.html>
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/CanSpecify.html>
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/Nearly.html>
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/Quadratic.html>
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/GrowUp.html>
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/Tautology.html>
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/Material.html>
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/GIVEN.html>
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/PythagoRescue.html>
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/SqrtRev.html>
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/NegSqrt.html>
<[Only registered users see links. ]
Androcyst and exclusive ors:
<[Only registered users see links. ]
Androcyst and partial differential equations:
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/PartialDiff.html>
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/PartialDiff2.html>
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/PartialDiff3.html>

--
Uncle Al
[Only registered users see links. ]
(Toxic URL! Unsafe for children and most mammals)
[Only registered users see links. ]
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