Research And Design Of UAV Attitude Measurement System Based On GPS Multi-antenna

Attitude information is the most critical prerequisite information for the UAV(Unmanned Aerial Vehicle)to achieve stable control and navigation.Its measurement accuracy directly determines the accuracy of UAV flight control.As UAV become more and more widely used,the measurement accuracy of UAV posture information becomes more stringent.Traditional attitude measurement methods mainly rely on inertial navigation systems which based inertial devices,but inertial devices are often expensive and its hardware structure is complex,in addition,the gyroscope will cause cumulative errors over a long period of time.GPS(Global Positioning System)is another important tool for attitude measurement because of its high precision and all-weather features.In this paper,GPS carrier phase attitude measurement technology is used to design a UAV attitude measurement system based on GPS multi-antenna.Around the system design,the following research was conducted: 1.This paper studies the technology of the two antennas sharing one internal clock source in a two-antenna receiver.Distinguished with the traditional attitude measurement method,a new baseline solution based on the carrier phase singledifference observation model is established.Aiming at solving the problem of carrier phase cycle slip in the attitude measurement process of GPS carrier phase,a method of cycle slips detection and repair based on Kalman filter algorithm is proposed.This method can effectively detect the occurrence of cycle slips and repair it in the next epoch.And the method can be applied to the observation data of various types of receivers.2.This paper studies the cause of Uncalibrated Phase Delay(UPD)and its effect on the ambiguity of the single-difference model.In this paper,the uncorrected phase delay is calculated with the single-difference model integer ambiguity as an unknown parameter.Combined with generalized constraint theory,a ambiguity fixing method based on the single-difference model is proposed.Compared with the traditional ambiguity fixing method LAMBDA based on double-difference model,the ambiguity fixing method based on the single-difference model not only eliminates the correlation between uncalibrated phase delay with single difference ambiguity,but also ensures the ambiguity resolution accuracy and speeds up the ambiguity fixed speed.3.In order to further improve the accuracy and reliability of GPS multi-antenna attitude measurement,this paper studies the layout of multiple antennas on UAV.Based on this hardware layout,an optimal estimation model for 3D attitude angle of UAV based on unconstrained adjustment method is proposed.This model makes full use of redundant information of multiple independent baseline vectors solved by multiple antennas,which effectively improves the accuracy and reliability of the solution of the attitude angle.4.Based on the above research contents,the attitude measurement system of UAV is designed in this paper.And the actual flight verification experiment of UAV attitude measurement system is carried out.The experimental results show that the accuracy of the yaw angle measured by the UAV attitude measurement system in this paper is 0.6238 degrees /(0.9863-meters baseline),the pitch angle accuracy is up to 0.5712 degrees /(0.9863-meters baseline),and the accuracy of the roll angle is up to 0.5291 Degrees/(0.9863-meters baseline).The above three-dimensional attitude angle measurement accuracy can satisfy the attitude determination requirements.