Accelerometer aiding about ethzasl_msf HOT 2 CLOSED

@nplayle ,

Orientation + Accel:
the accelerometers are used in the estimator to predict the position. (We do not use them in a separate orientation filter or in a complementary filter to estimate orientation.)

The only assumption we have in the framework is that the frame of reference of PTAM is roughly gravity aligned. (Usually this can be made sure by initializing ptam s.t. the control grid is horizontal). If the ptam frame of reference is not gravity aligned the estimator will estimate this rotation (world-to-vision transformation) and compensate for it. Of course this is only meaningful if the initial guess is not more than 10-20 degrees off.

The first thing I would verify is the imu to camera transformation. We expect you to set this in the parameter file. Here you have to provide the position and orientation of the camera frame of reference w.r.t. the imu frame of reference expressed in the imu frame of ref.

GNSS

The global yaw is only observable if you translate in a direction orthogonal to the direction of gravity. The roll and pitch are observable. We usually set the yaw to a reasonable guess at the beginning which we take from a compass.

pressure sensor

The units are expressed as metric height above a reference point which is stored at the filter initialization time.

Simon

from ethzasl_msf.

Assuming this is clarified.

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