Research On Flying Quality Evaluation Of Unmanned Aerial Vehicles

Flying qualities, which mainly indicate the stability and maneuverability of aircrafts, are very important criterions and guidance in their designs, R&Ds, testing and applications. In contrast with the booming development of unmanned aerial vehicles(UAVs), the flying qualities criterions of UAVs progress slowly. There are no systemic standards of how to define, calculate and evaluate the flying qualities of UAVs in neither theory nor practice as yet.In this paper, the huge differences between UAVs and manned aircrafts about flying qualities are investigated. UAVs are divided into remote controlled and automatic controlled by the manipulated patterns. Taking all the steps in maneuver into account, the system models which start from direct maneuver inputs and end with flying states are built. Based on these models, the calculating and evaluating methods of the flying qualities as well as the influences caused by primary aerodynamic layouts are studied.As to remote controlled UAVs, the frames of their manipulated processes are compared with those of manned aircrafts, in order to demonstrate the feasibility of taking manned aircrafts criterions as references to evaluating the flying qualities of UAVs. The models for evaluations should not only contain the basic aerodynamic equations, but start from the remote joysticks, and include the dynamic response of all aspects in the manipulated processes. Thus the flying qualities models of remote controlled UAVs are built. To be consistent with the referred criterions, the method based on pattern search optimization to match the low-order equivalent systems in frequency domain is studied. Some substances and indexes are modified to adapt the referred criterions for remote controlled UAVs, and their flying qualities evaluation system and process are built.As to automatic UAVs, the methods to deal with the nonlinear basic dynamic models are introduced. Classic PID control method is taken as an example to introduce the structure, the parameter tuning methods, and the adaptive technologies of flight control systems, which make it incapable to refer to the manned aircrafts criterions. A new way base on mission task element(MTE) to evaluate the flying qualities of automatic UAVs is studied and improved, and MTE qualities tables are proposed to replace the flying qualities levels. The process is also analyzed.With the varied aerodynamic layouts which were sensitive to traditional flying qualities, such as the stabilizer, the vertical tail, and the dihedral angle, the disturbed responses and manipulated responses of the automatic UAVs are simulated to evaluate the influence.