Improvement suggestions

[vegard-solum-4ss]

• Use accelerations (as well as velocities to calculate positon) in the strapdown algorithm. This is what Fossen and VectorNav does.
• Include the Coriolis term arising from the Earth's angular rate. This is what Gade and Vector nav does.
• Implement coning and sculling integrals (in sensor). The coning and sculling integrals can be performed at higher rates, which allows the integration of the acceleration and angular rate outputs to be performed at much lower speeds, thus reducing the amount of bandwidth needed to process the data.
• Use second order discretization of the state transition matrix.

[ali-cetin-4ss]

• Use second order discretization of the state transition matrix.

We should check if this significantly improves discretization errors at lower sampling rates.

[vegard-solum-4ss]

• Initial rotation from measurement frame to body-frame so that the algorithm estimates the attitude of the body-frame instead of the measurement frame.