Research On Mathematical And Reliability Analysis Of Multi-rotor Unmanned Aerial Vehicle

Since the 21 st century,along with the rapid development in the fields of computer technology,control technology,micro-sensor technology,brushless motor technology,multi-rotor unmanned aerial vehicle(multi-rotor UAV)has the advantages of aerial hover,vertical take-off and landing and can be adapted to narrow flight space with fixed wing UAV incomparable be hovering in the air,can adapt to the narrow space flight,more extensive application prospects both in civil and military fields are still,and the mechanical structure is relatively simple,so once again aroused people’s concern.Multi-rotor UAV is a system with time-varying nonlinearity and underactuated and strong coupling,and its precise dynamic model and flight control technology are difficult.In addition,because it is in the air,if the flight is out of control,its consequences are very serious.In this paper,the dynamic model of four rotors UAV is studied,the reliability of four rotors UAV is analyzed,the four rotor flight platform is simulated by the combination of fault tree and Monte Carlo simulation,and the reliability index is quantified.Firstly,this paper introduces the research background,development and development trend of multi rotor UAV,then defines the body coordinate system and the ground coordinate system of the multi rotor UAV prototype,and deduces the corresponding coordinate transformation matrix.By using the momentum theory,Eddycurrent theory and Blade-blade theory,the aerodynamic force and torque of the rotor blades are obtained through the dynamic analysis of the rotor of the multi rotor UAV,and the aerodynamic force and moment of the rotor are calculated by integral treatment.A nonlinear mathematical model of 12 parameters of multi-rotor UAV is established by Newton-Euler.Then,the prototype of the multi-rotor UAV was built.All parts need to build multi-rotor UAV prototype,such as frame,power source,motor,rotor,electronic governor,positioning device,remote control system,flight control board and other parts of the working principle,performance parameters,and the connection between them are introduced in detail.Analysis by using the theory of reliability analysis,mission reliability analysis and fault tree,establishes basic reliability model and its corresponding mission reliability model,and gives the assumption of multi-rotor UAV components are subject to exponential distribution,the corresponding basic reliability and task reliability calculation method.Based on the knowledge of fault tree,this paper analyzes the fault mode of multi-rotor UAV on the basis of the selection of top event,the determination of cut set and the minimum cut set,and the structure function of typical system.Finally,in this paper,the fault tree modeling of the multi-rotor UAV system is carried out,the model is simulated by Monte Carlo method,and the simulation results of the fault tree model are established to determine the probability fitting function of the flight mission failure time of the multi-rotor UAV in the 95% confidence interval.The results show that the study of the multi-rotor UAV system has better reliability components for the control of the handle,racks,rotors,remote control receiver,poor reliability of the elements,components for the electronic speed regulator,motor,geomagnetic meter,battery,for the design of the multi-rotor unmanned aircraft to make reasonable scientific improvements,provided a theoretical basis.