I completed the software part of my animatronic tail, and taken a pair of videos. The tail has his own software with 3 different modes: reset mode, programmed routines and full auto.
The reset mode put the servos at zero-position (90°) to help settings the strings lenght and tension. The programmed routines performs a series of pre-recorded movements (from top to bottom, from left to right, full circle clockwise and anticlockwise, etc). The full auto mode uses a series of algorithms to produce randoms movements.
All the movements are a mixed of linear and sine ramps, to give a different taste.
The two digital servos are controlled by an arduino nano, powered by a two cell hi-performance lipo battery and a controlled BEC.