Off-Axis Rotation Analysis

[MuffinSpawn]

Look for off-axis rotation patterns in the Argonne propeller coordinates data. Reproduce the predictions and look for explanations for why predictions were off in certain cases.

[MuffinSpawn]

There are observable sinusoidal deviations in the reflector's z coordinates as would be expected if there were a x-y plane tilt. The average large propeller tilt is 0.33225 +/- 0.00004 degrees. The average small propeller tilt is 0.533 +/- 0.002 degrees. The latter error is larger due to the fact that there are large deviations in rho for the small propellers of up to 14 mm (SP3). This suggests that the cantilever support is remaining at least partially bent in the same direction as the axis rotates, causing the small propeller to move in a circular manor around the axis. This is complicated by the fact that the bar will bend towards gravity.

[MuffinSpawn]

Here's a graph of small propeller reflector rotation paths:

[MuffinSpawn]

Here is just SP1 with an eyeball fit of a circle to the measured points:

This clearly suggests that propeller A is usually parked pointing upwards and has caused the cantilever to be bent downwards in this orientation. Since the rotation is off-axis with respect to the small propellers, the reflectors trace out off-axis circles and can be very badly modeled depending on what position was last measured.

This actually warrants consideration of adding a Kalman filter that tries to predict the off-axis, circular paths to get better predictions.