Research On Integrated Navigation System Under Maneuvering Conditions

With the rapid development of unmanned aerial vehicle(UAV)technology,UAV is widely applied in park security,power inspection,logistics distribution,scientific surveying and mapping,communication rescue,border defense and other fields.To adapt to the flight environment of high maneuverability and anti-interference,the requirements of UAV detection and identification are enhanced by the navigation system of UAV.The accuracy,stability and high reliability of the navigation system are the vital issues in the UAV navigation.However,a single navigation system can not guarantee its stability and accuracy for a long time.Due to the complexity of the environment,the global positioning system(GPS)will have the problem of signal loss or interference.Inertial navigation system(INS)errors will accumulate with time.To solve these above problems,this paper combines GPS and INS.for integrated navigation research,and an error state Kalman filter method is proposed for UAV,which is combined with INS and GPS multi-sensor fusion.Meanwhile,an integrated navigation system with high efficiency,accuracy,reliability and low cost is designed and implemented to meet the application requirements.The main research contents are as follows:(1)In this paper,the research status of inertial navigation and integrated navigation at home and abroad is discussed in details.And the advantages and disadvantages of INS and GPS are analyzed and compared.The differential equation derivation and error source analysis of inertial navigation position,speed and attitude are carried out.Aiming at the problem that a single navigation system can not guarantee its accuracy and reliability,a scheme of INS/GPS UAV integrated navigation system based on a loose coupling mode closed-loop structure is proposed to improve the navigation performance.(2)Aiming at the problems of poor real-time data collection by sensors and high hardware cost,a complete sensor data collection system platform is designed and built.The ADIS16488A based on inertial technology is used as inertial measurement unit.The STM32 single chip microcomputer is used as the core processor.And the OEM617D card is used as GPS output unit.The sensor data collection function is accomplished by the above units.Finally,the SD card data information is stored by the FATFS file system.And the performances of the proposed system are verified by the relevant experimental tests of the system platform.The final results illustrate that the data acquisition platform designed in this paper has the advantages of stability and reliability,real data,and convenient storage.It not only ensures lower design cost but also ensures real-time data acquisition.(3)For the problem of the drift of inertial navigation system induced by non-commutative error,an iterative updating method of equivalent rotation vector is proposed by constructing the angle increment output by the gyroscope.The non-commutative error caused by angular vibration is compensated,and the angular vibration’s influence is reduced through the proposed method.At the same time,the navigation accuracy is improved without reducing the output frequency of attitude update.The scheme is that the angle increment of the previous moment is used to compensate for the angle increment of the current moment.The essence of the optimal two-sample is the utilization of the angle increment of the previous and last periods.The experimental comparison verified that the improved algorithm can enhance the compensation accuracy of non-exchangeable error and reduce the drift error of inertial navigation without increasing the amount of calculation.(4)To solve the integral error drift of the strapdown inertial navigation system with time accumulation,an integrated navigation system is designed with INS and GPS complementary fusion.The INS/GPS loosely coupled error Kalman filter model is structured on the position error,velocity error,attitude error,gyro zero bias and acceleration zero bias and uses the Kalman filter technology.Position and velocity measurements are used in feedback correction.The performance of the system is tested by the simulation of flight test and on-set sports car test.By comparing the simulation and experimental results,it can be seen that the attitude angle accuracy is up to 0.01°;The eastward velocity is 60.79%higher than before;The northbound speed is increased by 63.55%;The celestial velocity is 91.46%higher than before.The positioning accuracy is corrected by feedback within the range of 3 meters error.The method can effectively compensate for the errors existing in the system,and ensure the high precision and reliability of the integrated navigation.The system makes the accuracy of speed and position raise one order of magnitude.