Acquired Accelerations
Posted: Fri Jun 06, 2014 12:14 am
Harry;
The other day I had some free time and was interested in finding out how good the iPhone accelerometer is... So.. Since I work in vehicle dynamics, I grabbed a PCB T356B08 tri-axis accelerometer along with my National Instruments setup running at 3200 Hz to do a little correlation work. I securely affixed the accel to the iPhone via the PCB paste and did some driving. I attempted to capture a sinusoidal lateral acceleration trace with increasing amplitude. Below are my results. FYI.. THe PCB trace has been LPF'ed by a 6th order butterworth filter with an Fc of 5Hz. I can send you the raw data and FFTs I used to ensure I captured most of the vehicle gross motion. However, after looking at the HLT data in the phone as well as the export... I found that the HLT data seems to scaled down by a factor of about 2.2. Is this something that has been done purposely based on your testing? Can you help explain the discrepancy? I am not trying to be a pain, just trying to learn. Thanks!!
The other day I had some free time and was interested in finding out how good the iPhone accelerometer is... So.. Since I work in vehicle dynamics, I grabbed a PCB T356B08 tri-axis accelerometer along with my National Instruments setup running at 3200 Hz to do a little correlation work. I securely affixed the accel to the iPhone via the PCB paste and did some driving. I attempted to capture a sinusoidal lateral acceleration trace with increasing amplitude. Below are my results. FYI.. THe PCB trace has been LPF'ed by a 6th order butterworth filter with an Fc of 5Hz. I can send you the raw data and FFTs I used to ensure I captured most of the vehicle gross motion. However, after looking at the HLT data in the phone as well as the export... I found that the HLT data seems to scaled down by a factor of about 2.2. Is this something that has been done purposely based on your testing? Can you help explain the discrepancy? I am not trying to be a pain, just trying to learn. Thanks!!