  Canard cycles are periodic orbits that appear as special solutions of
fast-slow systems (or singularly perturbed Ordinary Differential Equations). It
is well known that canard cycles are difficult to detect, hard to reproduce
numerically, and that they are sensible to exponentially small changes in
parameters. In this paper we combine techniques from geometric singular
perturbation theory, the blow-up method, and control theory, to design
controllers that stabilize canard cycles of planar fast-slow systems with a
folded critical manifold. As an application, we propose a controller that
produces stable mixed-mode oscillations in the van der Pol oscillator.
