Multi-Rate Path-Following Control for Unmanned Air Vehicles

A methodology is provided to tackle the path-following integrated guidance and control problem for unmanned air vehicles with measured outputs available at different rates. The path-following problem is addressed by defining a suitable non-linear path dependent error space to express the vehicle’s nonlinear dynamics. The main novelty of the method is to explicitly take into account the different temporal characteristics of the onboard sensor suite in the controller design and implementation. The proposed controller solution relies on a linear parameter varying structure that naturally exploits these multi-rate characteristics of the system outputs to obtain the desired properties for the resulting integrated guidance and control system. Due to the periodic time-varying characteristics of the multi-rate mechanism, the controller synthesis is dealt with under the scope of linear periodic systems theory. The effectiveness of the path-following methodology is accessed in simulation for low altitude terrain-following maneuvers of a small-scale helicopter using a full dynamic model of the vehicle.