Soft landing for electromagnetic actuators through adaptive pre-action combined with a slide surface to avoid electrical saturation

Electromagnetic actuators for industrial applications are being utilized more and more frequently. One of the most important requirements in the tracking trajectories problem is to achieve a soft landing. This guarantees reliable functionality and a longer component life. Real control applications are affected by saturation limits which generate slew rate and windup. This paper presents an industrial application of a typical electromagnetic actuator in which soft landing is required in a tracking trajectories problem during a closing phase. In order to avoid saturations, which do not allow enough soft landing, a specific control law is developed. The proposed technique is based on a cyclic adaptive current pre-action combined with a sliding surface. The technique consists of building a control law so that the point at which the velocity assumes its minimum is as close as possible to the landing point. At that point the magnetic force compensates for the elastic one. After that the pre-action component is switched off. An experimental setup is considered and real measurements of the proposed method are shown.