Science > Physics > What does a Accelerometer do? What instrument can I use
| Topic: |
Science > Physics |
| User: |
"Sea Squid" |
| Date: |
23 Feb 2005 12:27:19 AM |
| Object: |
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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| User: "Androcles Androcles@ MyPlace.org" |
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| Title: Re: What does a Accelerometer do? What instrument can I use |
23 Feb 2005 07:30:29 AM |
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"Sea Squid" <Sea.Squid@hotmail.com> wrote in message
news:421c20f7$1@news.starhub.net.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.
http://www.analog.com/en/prod/0,2877,ADXL202,00.html
http://en.wikipedia.org/wiki/Inertial_navigation
Androcles.
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| User: "Uncle Al" |
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| Title: Re: What does a Accelerometer do? What instrument can I use |
23 Feb 2005 10:03:18 AM |
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Androcles wrote:
[snip]
Androcles.
<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 fucked, idiot Androcles.
Nature 425 374 (2003)
<http://relativity.livingreviews.org/Articles/lrr-2003-1/>
http://www.eftaylor.com/pub/projecta.pdf
<http://www.public.asu.edu/~rjjacob/Lecture16.pdf>
Relativity in the GPS system. You are fucked, idiot Androcles.
<http://relativity.livingreviews.org/Articles/lrr-2003-1/>
http://arXiv.org/abs/gr-qc/0311039
<http://www.weburbia.demon.co.uk/physics/experiments.html>
Experimental constraints on General Relativity. You are fucked,
idiot Androcles.
Science 303(5661) 1143;1153 (2004)
http://arXiv.org/abs/astro-ph/0401086
http://arxiv.org/abs/astro-ph/0312071
Deeply relativistic neutron star binaries. You are fucked, idiot
Androcles.
Physics Today 57(7) 40 (2004)
http://physicstoday.org/vol-57/iss-7/p40.shtml
No aether. You are fucked, idiot Androcles.
http://fsweb.berry.edu/academic/mans/clane/
http://physicsweb.org/articles/world/17/3/7
No Lorentz violation. You are fucked, idiot Androcles.
<http://math.ucr.edu/home/baez/RelWWW/tests.html>
Mathematics of gravitation. You are fucked, idiot Androcles.
http://www.hep.upenn.edu/~max/toe.html
You are fucked, idiot Androcles.
http://www.iancgbell.clara.net/maths/spctime.htm
You are fucked, idiot Androcles.
<http://insti.physics.sunysb.edu/~siegel/Fields2.pdf>
You are fucked, 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-fucked psychotic idiot spewing
in a science newsgroup.
Androcyst and logs:
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/LogsHuh.html
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>
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/VectorSpaces.html
Androcyst and limits:
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/NegativeInfinity.html
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>
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/Think.html
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>
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/SqrtAnswers.html
Androcyst and exclusive ors:
<http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/Gibberish.html
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
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf
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| User: "Androcles Androcles@ MyPlace.org" |
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| Title: Re: What does a Accelerometer do? What instrument can I use |
23 Feb 2005 11:07:30 AM |
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The royal fuckwit "Uncle Al" <UncleAl0@hate.spam.net> wrote in message
news:421CA8D5.202258D0@hate.spam.net...
Why are you having so much trouble with basic algebra?
Let L_1 = distance light travels in going from Sam to Joe, as
measured in the stationary frame.
1) L_1 = cL/(c-v)
What a right royal stooopid *****.
See the peeing puppy moortel, he'll not be glad to add
you to his list of truly IMMORTAL fumbles. I will, though.
Androcles
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| User: "Sea Squid" |
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| Title: Re: What does a Accelerometer do? What instrument can I use |
24 Feb 2005 08:35:31 PM |
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Thank you Androcles!
I think the Analog chip is what I desire. I wonder, does "2 mg Resolution at
60 Hz "
mean 2e-3 * 9.8m/s^2 = 1.98cm/s^2 at frequency of 60Hz?
"Androcles" <Androcles@ MyPlace.org> wrote in message
news:Vz%Sd.158718$B8.154432@fe3.news.blueyonder.co.uk...
"Sea Squid" <Sea.Squid@hotmail.com> wrote in message
news:421c20f7$1@news.starhub.net.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.
http://www.analog.com/en/prod/0,2877,ADXL202,00.html
http://en.wikipedia.org/wiki/Inertial_navigation
Androcles.
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| User: "Ken Kubos" |
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| Title: Re: What does a Accelerometer do? What instrument can I use |
23 Feb 2005 07:33:12 AM |
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Check out: http://www.electronic-engineering.ch/study/ins/ins.html
--
Ken
"Buddhism elucidates why we are sentient."
"Sea Squid" <Sea.Squid@hotmail.com> wrote in message
news:421c20f7$1@news.starhub.net.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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| User: "Sea Squid" |
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| Title: Re: What does a Accelerometer do? What instrument can I use |
23 Feb 2005 12:40:14 AM |
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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" <Sea.Squid@hotmail.com> wrote in message
news:421c20f7$1@news.starhub.net.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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| User: "Franz Heymann" |
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| Title: Re: What does a Accelerometer do? What instrument can I use |
23 Feb 2005 02:51:36 AM |
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"Sea Squid" <Sea.Squid@hotmail.com> wrote in message
news:421c23ff$1@news.starhub.net.sg...
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"?).
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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| User: "CWatters" |
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| Title: Re: What does a Accelerometer do? What instrument can I use |
23 Feb 2005 02:37:56 AM |
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"Sea Squid" <Sea.Squid@hotmail.com> wrote in message
news:421c23ff$1@news.starhub.net.sg...
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"?).
Can you explain what the CPU will do with the data?
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| User: "Tom Potter" |
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| Title: Re: What does a Accelerometer do? What instrument can I use |
23 Feb 2005 05:37:58 AM |
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"Sea Squid" <Sea.Squid@hotmail.com> wrote in message
news:421c23ff$1@news.starhub.net.sg...
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"?).
Do a Google search on "rate gyro" and robot.
--
Tom Potter
http://home.earthlink.net/~tdp
http://photos.yahoo.com/tdp1001
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| User: "Andy Resnick" |
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| Title: Re: What does a Accelerometer do? What instrument can I use |
23 Feb 2005 07:44:04 AM |
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Sea Squid wrote:
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" <Sea.Squid@hotmail.com> wrote in message
news:421c20f7$1@news.starhub.net.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.
http://exploration.grc.nasa.gov/MSD/MSD_htmls/samsII.html
--
Andrew Resnick, Ph.D.
Department of Physiology and Biophysics
Case Western Reserve University
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| User: "Uncle Al" |
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| Title: Re: What does a Accelerometer do? What instrument can I use |
23 Feb 2005 10:12:45 AM |
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Sea Squid wrote:
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.
Buy a solid state 3-axis accelerometer.
Google
"solid state accelerometer" 383 hits
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf
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| User: "Androcles Androcles@ MyPlace.org" |
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| Title: Re: What does a Accelerometer do? What instrument can I use |
23 Feb 2005 11:07:41 AM |
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The royal fuckwit "Uncle Al" <UncleAl0@hate.spam.net> wrote in message
news:421CA8D5.202258D0@hate.spam.net...
Why are you having so much trouble with basic algebra?
Let L_1 = distance light travels in going from Sam to Joe, as
measured in the stationary frame.
1) L_1 = cL/(c-v)
What a right royal stooopid *****.
See the peeing puppy moortel, he'll not be glad to add
you to his list of truly IMMORTAL fumbles. I will, though.
Androcles
.
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| User: "PD" |
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| Title: Re: What does a Accelerometer do? What instrument can I use |
23 Feb 2005 10:46:53 AM |
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Sea Squid wrote:
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.
For a laboratory done at a local amusement park, my students used two
forms of accelerometers:
1. Vertical accelerometer. A plexiglass tube with one end capped, with
a fishing weight hung from a rubber band. Hanging one weight calibrates
1 "gee", hanging two weights calibrates 2 "gees", and that enables us
to mark the sides of the tube in "gees"
2. Horizontal accelerometer. A plastic protractor with a fishing
weight tied to a string which is also tied to the center of the
protractor. With zero "gees" the string hangs at 90 degrees, at one
"gee" the string hangs at 45 degrees, at two "gees" the string hangs at
30 degrees, etc.
An electronically instrumented version of these two things will do the
trick for you.
PD
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| User: "Randy Poe" |
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| Title: Re: What does a Accelerometer do? What instrument can I use |
23 Feb 2005 09:01:04 AM |
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Sea Squid wrote:
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.
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.
http://www.robotics.com/arobot/compass.html
I suspect those guys will also have suggestions for your
other navigation needs.
- Randy
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