For the MinVariance Controller, the formula is
\frac{(1+c)y(t)-cy(t-1)-T_{S,R}-\delta Y}{(1-c)a(t)} - \mu_U(t). The
previous implementation did not use y(t-1) in this formula. It used to
use current estimated PDR, not EWMA PDR. y(t) actually denotes EWMA PDR