Research On Control Law Technology Of The UAV Based On Dynamic Inversion

UAV maneuver performance has become an important index of flight control, and the nonlinearcontrol problems in designing the control law must be resolved. In this paper, in order to solve angularmotion coupling and inertial coupling produced in UAV flight, the nonlinear dynamic inversionmethod is applied to design the flight control law which can realize stability augmentation andthree-dimensional trajectory tracking in the full envelope.According to Newton’s theory of rigid body dynamics, nonlinear six-degrees-of-freedommathematical model is built, and its properties are analyzed including maneuver characteristics,control and stability characteristics, and motion characteristics. Combination with UAV dynamics andkimematics properties, the dynamic inversion control theory of the feedback system, single-variablesystem and multivariable system are deeply studied, which provided the design method for flightcontrol law of UAV.Secondly, after the analysis on the pitch axis angular motion and speed motion, the longitudinallinear model is built through the small disturbance theory. According to single-variable systemdynamic inverse control theory and the root locus method, the pitch angle rate control law, the pitchangle control law, the height tracking control law and speed control law are designed to realize thelongitudinal trajectory tracking and speed stability. After analysis of the nonlinear dynamiccharacteristics of the roll channel and yaw channel, the lateral attitude control law and the trajectorytracking control law are designed to weaken the coupling and achieve the lateral and directionalstability control.Finally, the nonlinear simulation platform is built in the Matlab/Simulink environment. Therobust of control law, the decoupling effect of control law and instruction tracing quality are verifiedby the application of Monte Carlo method, angle motion decoupling simulation and flight profilesimulation. Simulation results show that the control law based on the dynamic inversion meets therequirements of the attitude stability augmentation and the trajectory tracking control.