Algorithm 1. Detect candidate (window of last three accelerations)

If $\left|a_{n-1}\right|>\left|a_{n-2}\right| \&\& \left|a_n\right|$

Return (S = 1)

Elseif $\left|a_{n-1}\right|<\left|a_{n-2}\right| \&\& \left|a_n\right|$

Return (S = −1)

Else

Return (S = 0)