Research On GNSS/INS Combination Technology Based On UAV Platform

Rotor UAV has many advantages,such as light weight,small size and easy to carry.It is widely used in many civil occasions.Navigation system,as a very important part of Rotor UAV,is the basis of achieving smooth flight of Rotor UAV.Global Navigation Satellite System(GNSS)has the advantages of long time and high precision positioning,and the error does not accumulate over time.However,it is susceptible to external influence and the signal is easily occluded;Inertial Navigation System(INS)has the advantages of being free from external interference and high precision in short-time positioning,but the error will accumulate over time,so it is not suitable for long-time single positioning.Because of their complementary advantages and disadvantages,GNSS/INS integrated navigation system can make full use of the advantages of each subsystem,thus improving the positioning accuracy and reliability of Rotor UAV.Therefore,this paper focuses on GNSS/INS integrated navigation technology to meet the positioning requirements of Rotor UAV.The main research work and innovations of this paper can be summarized into the following four aspects:(1)INS: The basic navigation algorithm of INS in e-system is expounded from three important links: calculation of rotation matrix,update of speed and position and extraction of attitude angle.The initialization of INS is discussed in detail.(2)GNSS: It mainly introduces the composition of GNSS system,elaborates the principle and algorithm of GNSS pseudorange positioning based on least square method,and analyses various errors of GNSS positioning and their respective methods of eliminating or weakening them.(3)GNSS/INS: Discrete Kalman filtering algorithm,sequential Kalman filtering algorithm and smooth Kalman filtering algorithm are elaborated in detail.INS error equation and INS general state equation are derived,and the combined positioning model in e-system is expounded.(4)Experimental Study on GNSS/INS Combination:Based on field experimental datas of aircraft,the positioning results and positioning accuracy obtained under the conditions of satellite positioning,combined positioning and combined positioning after GNSS lockout are analyzed in detail.The advantages of GNSS/INS combination and the cumulative error of INS long-time positioning are demonstrated.At the same time,the results of standard Kalman filter combined positioning after GNSS unlocking and smooth Kalman filter combined positioning after GNSS unlocking are compared,which shows the advantages of smoothing after the event..