Fig. 2.

Methodological details. (a) input muscle activity was approximated by triangular waves, based on experimentally observed sEMG in tremor patients. Shown are detrended, rectified, and low-pass filtered sEMG signals from pectoralis major (solid gray) and lateral deltoid (dashed gray) muscles from a subject with severe tremor, compared to triangular waves (black), (b) Magnitude ratio of first submodel (excitation–contraction dynamics, with default values and $C=1$), along with the Fourier transforms of the input signal, $\mathit{u}$ (5 Hz triangle wave of width 110 ms), and the output, $\mathit{f}$, (c) The dynamics of the first submodel (muscle excitation–contraction dynamics) are illustrated by the submodel's impulse response, which represents a muscle twitch (simulated using default values and $C=1$), (d) Postures included in our simulation. Posture 1 is the default posture. Postures 2–4 were used in the sensitivity analysis. Posture 2: hand in front of mouth, representing feeding and grooming activities; Posture 3: hand in workspace in front of abdomen, representing many activities of daily living; and Posture 4: arm somewhat outstretched, representing reaching. Joint angles for each posture are given in Ref. [25].