| 摘要 |
PURPOSE:To prevent a system from entering an oscillation state unless the arithmetic result of a position is converged by deciding whether or not the difference between a position determined by navigation data and an estimated position is less than a specific value or not and updating the estimated value successively. CONSTITUTION:The navigation data sent from a satellite is received by a data receiving part 11a, an error arithmetic part 15a calculates the difference between the determined position and the estimated value specified by an initial estimate specifying part 13a, and a convergence deciding part 17a decides whether the error is less than the specific value or not. When the error is less than the specific value, the estimated value is outputted as the current value from a current position output part 19a. When it is decided that the error is larger than the specific value, on the other hand, an estimated value updating part 21a calculates a new estimated value, which replaces the estimated value inputted to the error arithmetic part 15a. For the purpose, the error calculated by the error arithmetic part 15a is inputted to a nonconvergence state deciding part 23a successively and when the current error is equal to or larger than said error, it is judged this state is a nonconvergence state, and the state is outputted to a warning device 27. |
