Figure 5.

Comparison of motor dynamics at low (${\zeta }_L=0.005$ pN-nm-s-rad⁻¹, shown as blue squares) and high (${\zeta }_L=0.5$ pN-nm-s-rad⁻¹, shown as red circles) loads. (a) Decrease in the average time between steps with increasing stator number results in an increase in duty ratio in the low-load regime. In contrast, at high loads, each stator step takes a considerable amount of time ($T_m$ is high), and the duty ratio is high even for single-stator motors. (b) As stators are recruited to fast-rotating motors (i.e., at low load), the number of independent stator steps per motor revolution $\left(n_{\text{steps}}\right)$ increases sublinearly from 26 steps/revolution for single-stator motors. At high loads, as predicted in (37), the steps per revolution is proportional to the number of stators. Note that $n_{\text{steps}}$ is the number of independent stepping events, and does not depend on experimental resolution. To see this figure in color, go online.