The Fujisaki model is interesting, in that it was the first model of intonation that attempted to explain it in terms of biology.  Unfortunately, it has no clean explanation for rising contours (such as Mandarin tone 2), and the accent commands that one derives from speech do not have a clean connection with syllables or accents or words or stressed syllables.   The basic problem with the Fujisaki model is that the muscle dynamics used is too simple.   Fujisaki assumed that muscles can be modeled by a damped harmonic oscillator response with constant response: constant stiffness, mass and damping.  Real muscles can adjust their stiffness to the task at hand, and the brain makes use of this ability.   Think of an arm swinging loosely at your side vs. an arm held stiff to stop a ball: it’s common, normal behavior, but not in Fujisaki’s math.