Research On Emergency Landing Control Technology For UAV

The emergency landing of UAV(unmanned aerial vehicle) after the engine cut-off, which iscomplicated and full of risk, is obviously different from normal landing, because of the loss of powerfrom throttle. Research on emergency landing control technology has become one of the mostimportant sections in system reliability of UAV. In addition to guarantee a safe gliding during thisprogress, scheme of emergency landing should also consider problems such as “whether UAV canreach the airport”,“how to make a feasible guidance” and “how to approach and land on the runway”.In order to solve these problems, this thesis designs a proper and engineering applicable controlstrategy for the sample UAV’s emergency landing.Firstly, the mathematical model of sample UAV is established by method of modular design.Characteristic of unpowered gliding is analyzed and compared with the one of normal landing, andfocal points of the following research are found according to the analysis on sample UAV.Secondly, based on the nonlinear equation of motion in space, a set of practical judgment method isproposed to estimate the UAV’s ability of flying to destination. The relationship among trajectory,dynamic pressure and height is found by analyzing the dynamic pressure profile and height profile ofsample UAV. Under the reference to this judging method, the ground operator can easily determinewhether UAV is able to come back safely.Thirdly, the whole landing progress is divided into several different flight phases, and the tasks ofeach flight phase are assigned, so that the UAV can have a well-guided fly back from the place whereits engine stops working to the destination.Furthermore, according to the characteristic of unpowered gliding of sample UAV, an improvedcontrol method for longitudinal channel, which is called “trajectory angle regulating control”, is putforward to make up the shortcoming of the control method used in normal landing and ensure thesafety during approaching and landing.Finally, nonlinear digital simulation and real-time simulation are performed to prove the reliabilityand effectiveness of the control strategy. And the results show that the control strategy proposed inthis thesis is of great practicality, and can perform well during unpowered emergency landing.