  This note proposes a novel nonlinear state feedback controller for perturbed
second-order systems. In analogy to a linear proportional-derivative (PD)
output feedback control, the proposed nonlinear scheme uses the output state of
interest and its time derivative for a robust finite-time regulation. The
control has only one free design parameter, and the closed-loop system is shown
to be uniformly asymptotically stable in the presence of matched disturbances.
We derive a strict Lyapunov function for the closed control loop with a bounded
exogenous perturbation, and use it for both the control tuning and analysis of
the finite-time convergence. Apart from the numerical results, a revealing
experimental example is also shown in favor of the proposed control and in
comparison with PD and sub-optimal nonlinear damping regulators.
