The Study Of High Dynamic GPS/INS Integrated Navigation System

With the emerging of the high-speed, high dynamic aircraft currently, it is important to study the aircraft navigation under high dynamic environment. GPS and INS are the two main types of navigation system currently. In high dynamic case, the dynamic of user can cause a great impact to GPS receiver's tracking loop and lead to the loss of GPS signal, then the GPS receiver lose the navigation capability. INS has anti-jamming, high dynamic flight and concealment features. In the high dynamic environment, the use of INS-aided GPS tracking loops can effectively improve the performance of GPS receiver to meet the navigation requirements. The GPS/INS integration navigation system is researched under high dynamic environment and the case of GPS signal interruption in this paper.The principle of the GPS receiver is analyzed firstly in this paper, the carrier tracking loop and code tracking loop of GPS receiver are introduced, the measurement error and tracking threshold of the GPS receiver tracking loop are analyzed and simulated, the impact to tracking loop caused by thermal noise and user's dynamic is analyzed. The performance of INS-aided GPS tracking loops is analyzed in order to solve the loss of the tracking loop under high dynamic case. All these analysis provides the theory for integrated navigation under high dynamic environment properly.The design of INS-aided GPS tracking loops need to change the internal of GPS receiver, it needs to control the parameters of receiver's tracking loop and difficulty to achieve in GPS chips currently. A scheme of using GPS software receiver instead of hardware is proposed in this paper, the Doppler frequency is calculated by satellite ephemeris and the location, velocity given by INS. Integrated navigation system using INS-aided GPS tracking loops based on position, velocity Kalman filter and pseudorange, pseudorange rate and ultra-tight coupled are described.The physical simulation of integrated navigation system under high dynamic environment is very difficult, the cost is also high. It is important to build a complete high dynamic simulation system. A block diagram of GPS/INS tight integrated navigation system simulation based on the theory of INS-aided GPS tracking loops is designed, the system consists of trajectory generator, INS simulator, high dynamic GPS IF signal simulator, real-time GPS software receiver, integrated navigation filters and so on. The GPS/INS integrated navigation simulation system is combined by the above test tools.Finally, the performance of GPS/INS tight integrated navigation system is simulated. Simulation results show that INS-aided GPS tracking loops largely unaffected by the dynamic stress influence, the errors of phase detector of receiver's tracking loop keep low level, GPS receiver can keep normal navigation solution, and the results of integrated navigation are effective. The performance of receiver under GPS signal interruption is good, the tracking loop can quickly resume tracking when the signal back to normal.