  This paper presents the design of a nonlinear control law for a typical
electromagnetic actuator system. Electromagnetic actuators are widely
implemented in industrial applications, and especially as linear positioning
system. In this work, we aim at taking into account a magnetic phenomenon that
is usually neglected: flux fringing. This issue is addressed with an uncertain
modeling approach. The proposed control law consists of two steps, a
backstepping control regulates the mechanical part and a sliding mode approach
controls the coil current and the magnetic force implicitly. An illustrative
example shows the effectiveness of the presented approach.
