Great improvement since the last video!

Are you just using Jacobian transpose for force control on the neck? I ask because it seems a bit stiff, the red marks on the neck of the test subject suggested to me that maybe there's a lot of noise in your force sensing, or at least unmodeled behavior.

Due to the slow growth of test subject hair, have you found 6$ to be cheap enough to keep your test cycles short enough?

The kinematic configuration of the arm looks odd, did you pick this to maximize rank of the Jacobian or the manipulability matrix?