Rahav The JustFATLogging data output axes do not correspond to those in Figure 1 in the manual. Take a look at Figs 5, 7 and 8. The alignment matrix entries give you an idea of what is happening. e.g. accel_alignment = [1 0 0;0 0 1;0 0 -1]gyro_alignment = [0 -1 0;-1 0 0;0 0 -1]mag_alignment = [1 0 0;0 1 0;0 0 -1] You could even do a visual check by opening up the shimmer unit, looking at the orientation of the sensors on the circuit board, and checking that against the sensor datasheet to confirm the axis alignment regards Chris
Date: Fri, 31 Aug 2012 09:36:59 -0700 From: [email protected] To: [email protected] Subject: Re: [Shimmer-users] Shimmer-users Digest, Vol 65, Issue 12 I assume that by default any Shimmer axes should correspond to how they are depicted in figure 1 on page 6 of the 9DOF user manual. Meaning, if one does not apply any correction to the raw data the Acceleration and Gyro axes are as they are displayed. With that said, if I am not going through the calibration process in 9DOF utility, I am just using the utility to see the steam of acceleration or gyroscope data, does this utility still applies some transformation on the raw data? If the answer is yes, then this may be the reason why 9DOF real time display shows the axes as they are depicted in the figure and JustFATLoggin does not. Is there a utility that does just stream the raw data? In JustFATLoggin the Gryo data does not agree with 9DOF on the X and Y axes. And the acceleration in JustFATLoggin X and Y axes are as depicted in the figure (and this matches 9DOF real time display), but the Z axis is reversed. Rahav Dor From: "[email protected]" <[email protected]> To: [email protected] Sent: Friday, August 31, 2012 11:00 AM Subject: Shimmer-users Digest, Vol 65, Issue 12 ----- Forwarded Message ----- Send Shimmer-users mailing list submissions to [email protected] To subscribe or unsubscribe via the World Wide Web, visit https://lists.eecs.harvard.edu/mailman/listinfo/shimmer-users or, via email, send a message with subject or body 'help' to [email protected] You can reach the person managing the list at [email protected] When replying, please edit your Subject line so it is more specific than "Re: Contents of Shimmer-users digest..." Today's Topics: 1. Re: JustFATLoggin axes vs Shimmer 9DOF (Chris B) the 9DOF calibration utility applies an alignment matrix to the decimal output (along with the scale factors and offsets). The alignment matrix contains axis order and sign, as well as any non-orthogonal corrections. JustFATLogging just outputs the decimal data as is, as far as i am aware, so you would need to apply the calibration coefficients to gain calibrated output with the correct axis order/sign. Take a look at the Calibration Utility manual. Chris Date: Thu, 30 Aug 2012 07:17:18 -0700 From: [email protected] To: [email protected] Subject: [Shimmer-users] JustFATLoggin axes vs Shimmer 9DOF I've modified JustFATLogging and the Shimmer provided MATLAB code to collect Gyro readings. I added the Gyro using: call GyroInit.init(); call GyroStdControl.start(); call shimmerAnalogSetup.addGyroInputs(); For debugging I decided to compare the data collected by JustFATLogging and Shimmer's 9DOF Calibration utility. It seems that when I position the Shimmer on its face (logo side) JustFATLogging thinks that it is the -Z acceleration axis (9DOF correctly shows that it is the +Z). When I check the gyro is seems that JustFATLogging and 9DOF do not agree on which is the X and which is the Y axis. In MATLAB I am reading the data by: sensorsData = fread(fid, [NUMBER_OF_CHANNELS,Inf], 'uint16'); accelx = sensorsData(1,:); accely = sensorsData(2,:); accelz = sensorsData(3,:); gyrox = sensorsData(4,:); gyroy = sensorsData(5,:); gyroz = sensorsData(6,:); What am I doing wrong? Thanks, Rahav Rahav Dor _______________________________________________ Shimmer-users mailing list [email protected] https://lists.eecs.harvard.edu/mailman/listinfo/shimmer-users _______________________________________________ Shimmer-users mailing list [email protected] https://lists.eecs.harvard.edu/mailman/listinfo/shimmer-users _______________________________________________ Shimmer-users mailing list [email protected] https://lists.eecs.harvard.edu/mailman/listinfo/shimmer-users
_______________________________________________ Shimmer-users mailing list [email protected] https://lists.eecs.harvard.edu/mailman/listinfo/shimmer-users
