Fig. 5.

Autocorrelation of $S_9$ speed and turning speed. a ${\text{ACF}}_u$ up to 5 s of lag with exponential approximation (black dashes) ${\text{ACF}}_u\approx exp(-t/{\mathit{\tau }}_u)$, ${\mathit{\tau }}_u=3.54$ s (b) ${\text{ACF}}_{\mathit{\omega }}$ up to 5 s of lag with ${\text{ACF}}_{\mathit{\omega }}\approx exp(-t/{\mathit{\tau }}_{\mathit{\omega }})$, ${\mathit{\tau }}_{\mathit{\omega }}=0.29$ s. Autocorrelation half-life for either process is thus approximated by $\mathit{\tau }\text{ln}(2)$, where $\mathit{\tau }$ is the one-step autocorrelation coefficient