search

mmalekzadeh / motion-sense

MotionSense Dataset for Human Activity and Attribute Recognition ( time-series data generated by smartphone's sensors: accelerometer and gyroscope) (PMC Journal) (IoTDI'19)
https://www.sciencedirect.com/science/article/pii/S1574119220300201
MIT License
326 stars 105 forks source link

Confusion about the userAcceleration data #5

Closed crocodilegogogo closed 3 years ago

crocodilegogogo commented 3 years ago

Hi Mmalekzadeh, Recently I downloaded analysed the Motion-sense dataset, which has four kind of features, namely attitude, rotationRate, userAcceleration and the gravity. RotationRate readings are the readings of the gyroscope, gravity readings are acquired from the readings of the accelerometer. However, I am confused whether the userAcceleration are the raw readings of the accelerometer, or the readings of linear acceleration (raw accelerometer readings minus the gravity readings). Please give me some advise!

                                                                                               Looking forward for your reply!
mmalekzadeh commented 3 years ago

Hi @crocodilegogogo

That userAcceleration shows the acceleration without the gravity force. So, in iOS, when you collect accelerometer data, the raw readings of the accelerometer are userAcceleration+gravity. Thus this userAcceleration is raw accelerometer readings minus the gravity readings.

Please read this for more context: https://developer.apple.com/documentation/coremotion/cmdevicemotion