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
