Real-time implementation of a sliding mode control scheme based on the unit vector approach, for a variety of underactuated configurations of a mechatronics kit (rotational, inertia, and double pendulum) is presented in this work. Details are given to perform diffeomorphisms leading to the required normal form, based on which design conditions are cast as linear matrix inequalities, thus improving numerical systematicness of the traditional methodology. Once the control law is designed, its implementation requires reliable estimates of the velocities since the different plants under consideration do not measure them; to this end, Levant's robust differentiator is employed. Results are provided that show the effectiveness of the proposal.