Robust and precise position determination for vehicles using GPS carrier phase measurements

An algorithm for resolving the GPS integer ambiguity is introduced. This algorithm is called the improved multiple-hypothesis Wald sequential probability ratio test (IMHWSPRT) and is based on a log formulation of the multiple-hypothesis Wald sequential probability ratio test (MHWSPRT). In this method the dynamic information is used as constraint. It speeds up the resolution convergence time of the integer ambiguity of GPS carrier phase measurements. It is known that the improvement of convergence speed of the MHWSPRT is due to the increase the probability ratio with the use of the dynamic information constraint. The dynamic information make the state error covariance small, it helps to speed up the resolution convergence time. But this method has weakness when the system model has faults. It is possible to reduce the effect of the faults by using the null matrix of the measurement model matrix. It is shown that IMHWSPRT is robust with the system model faults. The performance of IMHWSPRT is demonstrated using numerical simulations.