Research On Longitudinal Control System Design Of Autonomous Landing For Large Load UAV

Large Load Unmaned Air Vehicle(UAV)is paid much attention and finds wide favored in people’s eyes recently for its extraordinary efficiency in endurance,transportation and other aspects.Automatic landing control technology is related to the safe landing and effective recovery of UAV.The research of automatic landing control technology has profound research significance.Taking Large load UAV as the object and aiming at characteristics of diverse landing mass configuration and mass parameters are difficult to accurately obtain,this paper studied flaps using strategies and improve autonomous landing longitudinal control strategy on the basis of using flaps,which improved the consistency of landing flying state of the UAV in different mass and achieved the safe landing.Above all,the UAV’s characteristics is analyzed based on the UAV model.Flapless landing control strategy is also designed and analyzed and it is pointed out that the limitations of the control strategy is relying heavily on mass parameters and cannot achieve safe landing of whole mass configuration.The specific reasons influencing landing safety in detail is explained in this paper.Secondly,the flap operation strategy is designed to achieve the safe landing.In terms of the problem of angle of pitch when touching ground and insufficient security of rate of sink due to the fact that the mass parameter error,it is used to improve the control law that attitude control of series connection limiting and protection control of rate of sink when touching the ground based on direct force.The improved control law promoted landing safety of the UAV.Moreover,as for the problem of potential safety hazard and lacking the capacity for independent correction when using the flaps,The automatic flap control strategy is designed to make UAV gradually breaks away from the weight parameter dependence and independently correct deviation of flight status when in entry level flight through the independent correction control of flight state deviation of control law,which improved the autonomy and security of the landing control.Finally,equivalent simulation environment was designed based on FixWingLib model,on which basis compostable simulation of whole mass configuration and various interference factors are conducted.Simulation results show that the control strategy designed in this paper can effectively improve the consistency of landing state of UAV with different weight,and achieve safe landing.