This study introduces the accurate correction method of bearing position error of mobile robots using Stargazer sensor. The mobile robots require some vital functions including map building, localization, path planning, obstacle avoidance for autonomous navigation. In most cases, the localization of angular pose of a robot is essential because its result has a great effect on the performance of the other functions. We demonstrated the validity of the proposed method with the results of real experiments and applied it to the photographer robot for correct bearing position error at the moment of taking a picture.

In order to get more accurate GPS position with the changes of the inner configuration setting of GPS receiver, the authors carried out measurements of the position at known it with one antenna and two GPS receivers manufactured by same company. We have investigated the accuracies of positions according to the change of the maskangle and receiving mode of output data in inner configuration of GPS receivers, and analyzed the relationships between numbers of satellites visibility and maskangles, and values of HDOP and maskangles. When the maskangles in inner configuration were set below 20 degree, the accuracies of positions were high. But if they were became bigger than 25 degree, standard deviations ot position errors and HDOPS of positions were became bigger. Numbers of satellites visibility(y) and maskangles(x) have relations with a formula, y = -0.1662x+9.9225, and values of HDOP(y) and maskangles(x) have relations with a formula, y = 0.6035 e0.0517x. The results of position accuracies observed by two GPS receivers to the known position at same time were that average errors of position fixs by GPS receiver configured with NMEA0183 mode were 6.7m and standard deviations were 1.5m, and them by GPS receiver configured with binary mode were 5.0m and standard deviations were 1.1m respectively.

As the NNSS system calculates ship's position by the doppler shift of the NNSS radio waves caused by the change of the distance between Transit Satellite and the ship, ship's speed error inevitably results in the position error, and moreover this kind of erroris most dominant compared with other errors especially in high speed ships and airplanes. Most NNSS receivers now in use have adoptedsuccessive short doppler counts as positioning data and by investigating the dispersion of serval successive positions calculated and by neglecting the mean position having dispersion of over certain threshold level, more accurate adn safe position is to be achieved. This paper proposes the method of finding ship's true speed by selecting a speed having least position dispersion for given successive doppler counts. And by computer simulation it was verified that the method proposed here is reasonable in finding the ship's desired correct speed together with the correct ship's position.