Aircraft Control System Design Based On Sliding Mode Variable Structure

UAV is referred to short for Unmanned Aerial Vehicle. It is a power-driven, unmannedand reusable spacecraft. UAV has been widely used in the military field, and it increasinglyprominent advantages in the civilian. At present, the UAV has popular all over the world along time ago, UAV flight control technology needs to be improved. Thus, the development ofto improve UAV flight automatic control technology has become a priority. UAV automaticflight control system is a core part of the UAV. UAV’s performance largely depends on itsflight control laws design. These features include a variety of flight performance(includingtakeoff and landing performance, flight operations performance, reliability of flight safety,flight monitors, automation and maintainability of of system, etc). Therefore, the researchUAV automatic flight control technology has great significance.In this paper, the UAV flight control system focusing on its pitch channel control lawdesign, the control law based on sliding mode variable structure theory, simulation analysisand verification the control system.First, introduction the UAV coordinate system, then create a mathematical model of theUAV movement and the UAV space motion decoupling and linearization processing, get theUAV pitch channel linear equations. To establish the mathematical model of the UAVmovement analysis and design of the primary flight control system, laid the foundation for theanalysis and design of UAV flight control system.Secondly, introduction the typical UAV flight control system of the overall structure andworking principle. Based on the understanding of the relevant knowledge, analyzed thepitching motion characteristics of the UAV. The research focus on the UAV vertical movementof short-cycle mode, expectations indicators for UAV flight control system natural frequencyand damping ratio, using traditional control design a UAV pitch channel automaticthe flightcontrol system, simulation and analysis the control system.Then, introduce the principle of sliding mode variable structure control and variablestructure system problems buffeting, and analyze the causes of buffeting. The use of variablestructure control system external interference within the system parameter perturbation andinvariability of UAV flight control system design. Switching function in the design, selectionindex reaching law to weaken the chattering, but the effect is not ideal.Consider the limitingfactor of the system control, using adaptive sliding mode variable structure method weakenthe variable structure control system buffeting, the simulation results show that this methodcan be reduced the buffeting of the variable structure system to a very small extent.. Finally, simulation and analysis the design of the sliding mode variable structure controlsystem, and compared with the traditional control results. Simulation results show that thedesign of the sliding mode variable structure control system has a good capacity forself-government and anti-jamming ability when the UAV changes airspace, obtain satisfactorycontrol results,it has certain theoretical and practical significance.