To the best of our knowledge, we are the first to carry out
a detailed analysis about the individual and combined roles of
an accelerometer, a gyroscope and a magnetometer in physical
activity recognition. In this work, we answer the question that
in which situations an accelerometer performs better than a
gyroscope and vice versa and why or when to combine the
two sensors for better recognition performance? It is very
important to answer this question because it enables us to use
an appropriate sensor for the right activity, rather than just
combining many sensors because more sensors mean more
energy consumption for the smartphone battery. For this
purpose, we evaluate each sensor individually as well as in
combination with other sensors, to assess its individual and
combined ability in activity recognition