  Novel nonlinear damping control is proposed for the second-order systems. The
proportional output feedback is combined with the damping term which is
quadratic to the output derivative and inverse to the set-point distance. The
global stability, passivity property, and convergence time and accuracy are
demonstrated. Also the control saturation case is explicitly analyzed. The
suggested nonlinear damping is denoted as optimal since requiring no design
additional parameters and ensuring a fast convergence, without transient
overshoots for a non-saturated and one transient overshoot for a saturated
control configuration.
