The motion description of an airborne wind energy (AWE) system is very complex and is not suitable to design a controller. In recent years, simplified models have been developed for this kind of systems. In this paper a controller is designed using a simplified model and is based on the sliding mode technique. The designed controller is robust against model uncertainties and disturbances in wind velocity. Some simulation results are presented with a complete generation cycle where the wind velocity and the kite glide ratio are perturbed.