Tracking and disturbance rejection for SISO positive LTI systems via LQR clamping

In this paper we consider the servomechanism problem for SISO positive LTI systems. In particular, we solve the servomechanism problem of nonnegative constant reference signals for stable SISO positive known LTI systems with unmeasurable unknown constant nonnegative disturbances under strictly nonnegative control inputs, using a clamping LQR regulator.