Can magnetic field sensors replace gyroscopes in wearable sensing applications?

We investigate if and how magnetic sensors can be used to replace gyroscopes in wearable activity recognition. The work is motivated by (1) sensor configurations typically found in smart phones where magnetic sensors are used to complement GPS position with orientation and (2) the fact that gyroscopes are an important source of information for activity recognition. We propose a method to compute angular velocity from 3D magnetic sensor data and discuss its fundamental limitations. We present an elaborate evaluation of the accuracy on 5 previously published data set with a total of nearly 20 hours of data from 15 users with activities ranging from bicycle repair, through homemaking to gym exercise.