Musculoskeletal resonance

Short definition

Musculoskeletal resonance of a joint: f_km = (1/2π)·√(K_joint / J_eff); in VibroTheory computed for the elbow axis via BioSim.

Full definition

The musculoskeletal resonance couples joint-muscle stiffness with limb inertia. An activated muscle acts as a spring: K_i = (a · F_max_i / L_opt_i) · |MA_i|, summed for K_joint (moment arms from the MergedV6 model). J_eff ≈ (1/3)·m_forearm·L² + m_hand·L² ≈ 0.05–0.2 kg·m² for the elbow. f_km depends on activation level and user mass; it is charted with a purple marker.

Examples

Elbow axis: msk resonance ≈ 14.7 Hz at 80 kg with chained inertia J = 0.065 kg·m² — inside the sweep band.

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