initialize the system covariance matrix with non-zero
values for the gyro-bias part. this improves the initial
bias estimation speed significantly.
the initial covariance matrix should be small because the drift
changes slowly. the real problem is that we're not starting with
a good estimate of the drift, which this algorithm relies on.
so with this revert, it'll take a while for the drift to be estimated
but it won't be unstable.
Change-Id: Id5584bc114a2390d507643b2451b2650c1b90721
we now use a better quaternion propagation equation
this is especially beneficial for lower gyroscope rates
Change-Id: Ifbf273c8a092a8849ca4fe4b9bca30787e924018
1) there was a typo when computing the system covariance
a term in dT^3 was ommitted; the impact was was very limited
because of how small this term is.
2) initialize the system covariance matrix with non-zero
values for the gyro-bias part. this improves the initial
bias estimation speed significantly.
3) added comments here and there
Change-Id: I4328c9cca73e089889d5e74b9fda99d7831762dc
also use correct time propagation equation
disable the fused sensors when gyro is not present since
they were unusable in practice.
Change-Id: Iad797425784e67dc6c5690e97c71c583418cc5b5
Add support for 9-axis gravity and linear-acceleration sensors
virtual orientation sensor using 9-axis fusion
Change-Id: I6717539373fce781c10e97b6fa59f68a831a592f
