Aerodynamics Model/Inertial Sensor/GPS Fault Tolerance Navigation Method For Multi-rotor UAV

Multi-rotor UAV has the advantages of simple structure,easy control,hovering and vertical take-off and landing.It is widely used for monitoring,investigation and other tasks in the near ground environment with a wide range of military and civil prospects.Navigation technology is the key to ensure the completion of tasks of multi rotorcraft.At present,MEMS-INS/ GPS/ magnetic sensor/ barometric altimeter integrated navigation scheme is usually used in multi-rotor UAV.Due to the cost control and load limitation of multi-rotor UAV,the accuracy of the airborne navigation sensor is low.Navigation performance is of great dependence on GPS.The navigation error diverges rapidly if GPS signal is disturbed,blocked or shielded during the flight.Therefore,how to improve the navigation accuracy and reliability of multi-rotor UAV in different environments is one of the important topics of the current domestic and international scholars.The aerodynamics model aided navigation technology is a new independent navigation method,which has the advantages of good self-contained,low cost and wide range of application.In recent years,it has been paid attention to by scholars at home and abroad,and preliminary research and verifications were carried out.By now,the discussions of the aerodynamics model aided navigation method are mostly carried out in an ideal environment.There are still some key problems about the navigation accuracy and reliability to be solved in practical application.For example,the on-line identification of aerodynamic model parameters,the disturbance of wind on aerodynamic model and the further application of aerodynamic model in fault tolerant navigation.To overcome these problems,the aerodynamics characteristics of multi-rotor UAV are analyzed,and an aerodynamics model suitable for aiding navigation is establishes.Based on the model,an aerodynamics model aided inertial independent navigation scheme for multi-rotor UAV is proposed.Then,an real time online estimation method for aerodynamic parameters of multi-rotor UAV aerodynamics model is presented,in order to tackle the problem that the aerodynamic parameters can not reflect the time-varying characteristics of the model.Meanwhile,the feasibility of the online estimation scheme for aerodynamic parameters is verified through the null space observability analysis method.The simulation analysis is carried out,and the results verify that the method can effectively improve the estimation accuracy of velocity and position compared with offline identification scheme.Aiming at the disturbance of the wind field for aerodynamic model,an aerodynamics model/ inertial independent fault tolerant navigation scheme for multi-rotor UAV based on multi model technique is proposed.In this scheme,different models of multi-rotor UAV in different wind fields are established,and then filtering fusion based on multi model estimation algorithm is performed.It can effectively improve the navigation reliability of multi-rotor UAV under the wind environment.Also,an aerodynamics model/ inertial sensor/ GPS fault tolerance navigation method for multi-rotor UAV is presented.It has good diagnosis and fault tolerance capability for the aerodynamics and GPS fault under the condition of bad flying environment or high maneuvering flight.The simulation results show that the two schemes can effectively improve the navigation reliability of multi-rotor UAV when the aerodynamic model is not accurate or in GPS-denied circumstance.Finally,the simulation and rotorcraft flight verification are carried out.Aerodynamics model/ inertial sensor/ GPS fault tolerance navigation scheme of multi-rotor UAV is comprehensively verified by hovering and autonomous flight.The experiment results show that aerodynamics model/ inertial sensor/ GPS fault tolerance navigation scheme can improve the navigation accuracy and reliability greatly compared with the traditional inertial navigation system.Thus,the correctness,superiority and practical value of aerodynamics model/ inertial sensor/ GPS fault tolerance navigation scheme is verified.