Optimal Workloop Energetics of Muscle-Actuated Systems: An Impedance Matching View
Figure 3
The optimal stimulation frequency () for a mass-spring-damper system actuated by a muscle is greater than the natural frequency of the load (
).
(A & B) Results of dynamic optimizations. Each point in the plots represents a solution similar to that of Figure 2. For an impedance-free actuator (gray), the optimal frequency coincides with the load natural frequency, whereas for the bilinear muscle model incorporating activation dependent stiffness (black) the optimal frequency is greater. Results are shown for simulations with Hz,
and
N/m (A), and
Hz,
and
N/m (B). (C & D) Experimental measurements of power ratios shown for each measurement set. Workloop power measurements in each set are normalized by
. The error bars at
are therefore equal to zero by definition. Both figures show that
and
. The asterisks indicated the
value, with (**) for
and (*) for
. (C) Measurements taken across 3 muscle for load natural frequency
Hz,
and
N/m. (D) Measurements taken across 2 muscles for load natural frequency
Hz,
and
N/m.