Harry's GPS Suite Forum

Thanks for this. I have set the acceleration data at 60Hz, but on your advice I will up it to 100Hz.
I was more concerned about validity of the acceleration readings once you start moving mostly sideways on the track.

The readings will still be valid for the vehicle frame of reference. But at high yaw angles, they won't look the same as values calculated from GPS data in the Earth frame, assuming your GPS antenna is reasonably close to the center of mass of your car. In theory you could calculate the yaw angle from the angle needed to rotationally transform the accelerometer data to match the GPS data. The problem is that you really need the rotation rate data as well as the accelerometer data from the IMU in the phone to do the job right. Even better would be magnetometer data as well so you know the orientation of the vehicle in the Earth frame of reference. Comparing that to the GPS direction gives you the yaw angle directly. Maybe someday.