  For a wide class of second order nonlinear non-autonomous models, we
illustrate that combining proportional state control with the feedback that is
proportional to the derivative of the chaotic signal, allows to stabilize
unstable motions of the system. The delays are variable, which leads to more
flexible controls permitting delay perturbations; only delay bounds are
significant for stabilization by a delayed control. The results are applied to
the sunflower equation which has an infinite number of equilibrium points.
