Fix angular locked axes in gyroscopic torque computation#485
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Jondolf
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Aug 19, 2024
# Objective I think that #485 wasn't quite the right fix for #474 - applying locked axes to an inertia tensor zeros out one or more of its rows, making the matrix singular - taking the inverse then results in a matrix that's all NaNs, making the delta_ang_vel also all NaNs, which causes the angular momentum to be unaffected by anything that timestep (including applied torques!). The problem with the status quo ante seems to be that a similar thing happened - rather than trying to invert the (singular) locked inverse inertia, the calculated Jacobian was (near-)singular in a lot of cases when axes were locked, and depending on round-off errors you'd either get NaNs or just an outright cancellation of the angular velocity ## Solution Calculating the delta-ω from gyroscopic effects with an unconstrained inertia matrix and *then* applying the locked axes to that angular velocity increment should be more reliable, and should avoid undesirable NaN values showing up
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Objective
Fixes #474.
The angular locked axes are applied to the inertia instead of the inverse inertia in gyroscopic torque computations introduced in #420, causing incorrect behavior.
Solution
Apply the locked axes correctly.