Sounds like some signal processing/filter math is in order. http://www.cs.unc.edu/~welch/kalman/
Anyone with experience? D On Jul 9, 1:18 pm, dilit <[email protected]> wrote: > Just in case, > > We did calibrate our phones. > E.g. My phone's Gravity value is more like 8.7 vs 9.81. > While static, the phone's accel values were acceptable. > As soon as the phone was in motion, the acceleration (position) > data went out to lunch. > > FYI, marketing = lying 99% of the time. IMO > > On Jul 9, 1:05 pm, dilit <[email protected]> wrote: > > > > > We are writing an application that uses acceleration sensor data to > > plot phone's movement in 3D. > > We are finding gross inconsistencies in the actual data output by the > > sensor. Also, sampling rates > > vary greatly from 8 to 200 millis. (using System.currentTimeMillis()) > > > Specifically, when we try to draw a circle with G1 flat on the table > > all the time (filtering out gravity accel 9.8), > > most of the time we would get a plot of phone's position that is not a > > circle at all. Lots of times, it would be close to a straight line. > > Sometimes, it would start drawing an arc, but would not close the > > circle shooting off in a random direction. > > > We tried to eliminate the time variable, by substituting a constant > > time sampling rate (10 millis) to calculate phones position, but the > > result was > > very close to what we had before (shapewise). Also, the acceleration > > in Z direction when the phone is displaced lying flat on a table (XY > > plane) varies too > > by +/- 2 units which is a lot. > > > I do not think it is an error in our code, as we have checked it many > > times. If there were an error indeed and the > > accelerometer worked properly, we would see a consistently wrong > > depiction of the phone's movement. Unfortunately, repeating the same > > movement > > (circle) would produce sometimes wildly differently shaped plots. > > > It all comes down to us wanting to know if that is indeed the case > > that the G1 accelerometer is very unreliable and inconsistent device > > when used for more or less precise > > measurements? Is there some documentation/facts paper that would tell > > us just how reliable accelerometer is? > > > Thanks for you help! > > Dmitriy --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/android-developers?hl=en -~----------~----~----~----~------~----~------~--~---
