For classical TCAR(three carrier ambiguity resolution)algorithm is affected by ionospheric delay and measurement noise,it is difficult to reliably fix ambiguity at medium and long baselines.An improved TCAR algorithm ...For classical TCAR(three carrier ambiguity resolution)algorithm is affected by ionospheric delay and measurement noise,it is difficult to reliably fix ambiguity at medium and long baselines.An improved TCAR algorithm which takes the influence of ionospheric delay into account and has good adaptive robustness is proposed.On the basis of the non-geometric TCAR model,ionospheric delay is obtained by linearly combining extra-wide-lane with fixed ambiguity,and then wide-lane ambiguity is solved.Solving narrow-lane ambiguity by adaptive robust filtering by constructing optimal combination observation,which can effectively improve the fixed success rate of narrow-lane ambiguity and reduce the adverse effects of gross error.Experimental results show that the improved TCAR algorithm can guarantee a high fixed correct rate of wide-lane ambiguity,effectively improve fixed success rate of narrow-lane ambiguity,and has a good ability to resist gross error.展开更多
When the initial position error or the altimeter measurement noise is large,the BUAA Inertial Terrain-Aided Navigation (BITAN) algorithm based on extended Kalman filtering can not be located accurately.To solve this p...When the initial position error or the altimeter measurement noise is large,the BUAA Inertial Terrain-Aided Navigation (BITAN) algorithm based on extended Kalman filtering can not be located accurately.To solve this problem,we propose a modified BITAN algorithm based on nonlinear optimal filtering.The posterior probability density correction is obtained by using the prior probability density of the system's state transition model and the most recent observations.Hence,the local unobservable system caused by the measurement equation through terrain linearization is avoided.This algorithm is tested by using the digital elevation model and flight data,and is compared with BITAN.Results show that the accuracy of the proposed algorithm is higher than BITAN,and the robustness of the system is improved.展开更多
文摘For classical TCAR(three carrier ambiguity resolution)algorithm is affected by ionospheric delay and measurement noise,it is difficult to reliably fix ambiguity at medium and long baselines.An improved TCAR algorithm which takes the influence of ionospheric delay into account and has good adaptive robustness is proposed.On the basis of the non-geometric TCAR model,ionospheric delay is obtained by linearly combining extra-wide-lane with fixed ambiguity,and then wide-lane ambiguity is solved.Solving narrow-lane ambiguity by adaptive robust filtering by constructing optimal combination observation,which can effectively improve the fixed success rate of narrow-lane ambiguity and reduce the adverse effects of gross error.Experimental results show that the improved TCAR algorithm can guarantee a high fixed correct rate of wide-lane ambiguity,effectively improve fixed success rate of narrow-lane ambiguity,and has a good ability to resist gross error.
基金supported by the National Natural Science Foundation of China (Grant No.61039003)the Aeronautical Science Foundation of China (Grant Nos.20090818004 and 20100851018)the National Key Laboratory Foundation
文摘When the initial position error or the altimeter measurement noise is large,the BUAA Inertial Terrain-Aided Navigation (BITAN) algorithm based on extended Kalman filtering can not be located accurately.To solve this problem,we propose a modified BITAN algorithm based on nonlinear optimal filtering.The posterior probability density correction is obtained by using the prior probability density of the system's state transition model and the most recent observations.Hence,the local unobservable system caused by the measurement equation through terrain linearization is avoided.This algorithm is tested by using the digital elevation model and flight data,and is compared with BITAN.Results show that the accuracy of the proposed algorithm is higher than BITAN,and the robustness of the system is improved.
