**** BEGIN LOGGING AT Wed Apr 27 02:59:58 2011
Apr 27 12:49:24 <jivs> Hi I need some help on understanding the accelerometer data in Openmoko. plz help
Apr 27 12:49:52 <jivs> I am retrieving the data using a simple C program
Apr 27 12:50:04 <SpeedEvil> What help
Apr 27 12:50:16 <SpeedEvil> You get x/y/z acelleration out.
Apr 27 12:50:29 <SpeedEvil> Oriented as to the phone.
Apr 27 12:50:46 <jivs> Not sure what the values mean ?
Apr 27 12:50:58 <``{_|_}``> jivs, watch soruce of mokomaze
Apr 27 12:51:01 <``{_|_}``> will help!
Apr 27 12:51:14 <SpeedEvil> i see your question, so I have written this page to explain accellerometer in the OM phones for you.
Apr 27 12:51:18 <SpeedEvil> http://wiki.openmoko.org/wiki/Technical:Accelerometer_Fundamentals
Apr 27 12:51:48 <jivs> i am getting data like this, x : 18 , y :72 , and z : 270
Apr 27 12:51:50 <jivs> thank you
Apr 27 12:52:00 <jivs> I will go through both of them
Apr 27 12:54:31 <SpeedEvil> The num bers are in milligee IIRC
Apr 27 12:54:57 <SpeedEvil> So x = 18 - it's accellerating inthe X direction by 18 milligee - or 18*10m/s^2
Apr 27 15:34:33 <jivs> SpeedEvil,  if the value openmoko is providing is acceleration , is it possible to calculate displacement
Apr 27 15:38:35 <jivs> for ex. with x= 18 mg, displacement = 1/2 * 18/1000 (cm/s/s) * 0.01 (time)
Apr 27 15:39:44 <jivs> using the formula s=u * t + 1/2 a * t2 (assuming initial velocity is 0)
Apr 27 15:47:28 <SpeedEvil> No.
Apr 27 15:47:33 <SpeedEvil> Well - sort-of
Apr 27 15:47:40 <SpeedEvil> See the calculations in the above page
Apr 27 15:47:57 <SpeedEvil> Even if you know the orientation, the rrors _rapidly_ build up.
Apr 27 15:48:10 <SpeedEvil> To the level of a kilometer or so in a minute from memory
Apr 27 15:54:12 <jivs> Do you have any idea if the Macbook or Thinkpad accelerometer operate the same way as openmoko
Apr 27 15:54:36 <SpeedEvil> Pretty much.
Apr 27 15:54:48 <SpeedEvil> Exact parameters vary by anorder of magnitude or so.
Apr 27 15:54:52 <jivs> I have used those accelerometer data, basically they write the x,y coordinates to a text like file.
Apr 27 15:55:32 <jivs> but i think they write displacement to the file rather than acceleration.
Apr 27 15:56:07 <jivs> as the data fluctuation in openmoko is very high with compare to macbook accelerometer data
Apr 27 15:59:02 <SpeedEvil> They don't.
Apr 27 15:59:06 <SpeedEvil> They can't.
Apr 27 15:59:18 <SpeedEvil> No sensor invented canmeasure position.
Apr 27 15:59:24 <SpeedEvil> Well - no portable sensor
Apr 27 15:59:36 <SpeedEvil> Unless you're talking about GPS
Apr 27 16:05:22 <jivs> oh
Apr 27 16:05:47 <jivs> no i am talking only about accelerometers.
Apr 27 16:06:28 <jivs> so it must be gal or milligal everyone uses for these acceleration data
Apr 27 16:18:52 <jivs> I am planing to plot the openmoko acceleration for my research, can i use the x data it is generating like x/1000, and same for y and z 
Apr 27 16:19:20 <jivs> e.g. if i am getting 18 for instance, will it be 0.018?
Apr 27 16:19:40 <jivs> I am bit confused how to scale the data i am receiving..
Apr 27 16:50:56 <PaulFertser> jivs: hi
Apr 27 16:51:36 <PaulFertser> jivs: if you still do not know the answer, ping me and i'll look through the sources.
Apr 27 16:54:38 <jivs> Hi Paul
Apr 27 16:55:33 <jivs> yes still not sure about whether the data openmoko accelerometer is giving should be used as it is or need some scaling.
**** ENDING LOGGING AT Thu Apr 28 02:59:57 2011