Integrated projection guidance and nonlinear control of unmanned air vehicle

In this study, an integrated projection guidance and nonlinear flight control law (IPGNFC) is proposed for the unmanned air vehicle (UAV). Testing procedures of the IPGNFC and the results of the testing are reported. To realistically evaluate the design and to compare the results of different types of simulation, the simulation was done on nonreal-time PC and the real-time two PC platform. The two PC in the platform are connected by AD/DA interface cards and can run in parallel. For designing the IPGNFC, the control law can be divided into the guidance and the flight control problem. The guidance problem, based on the point mass model, is to keep the air vehicle stay on a flight trajectory toward the target location with constant air speed. Instead of using the traditional gain scheduling method, the flight controller is designed with nonlinear feedback theory. By the use of singular perturbation, the aircraft system dynamics is separated into fast and slow model. Then feedback linearization and sliding mode control were used to design a robust flight controller. A test case is included which requires the proposed IPGNFC to lead an UAV to arrive at a preset target position and to perform a circling maneuver.