Mobile robot localization system in frequent GPS-denied situations

In this paper, we propose a mobile robot localization system in frequent GPS-denied situations. We utilize multiple observations that are obtained from sequential appearance-based place recognition and GPS. Using GPS observations has still some challenging problems such as multipath or signal lost under environments where there are tall buildings nearby. The appearance-based place recognition that is combined with positional information has capability to overcome the issue. Nevertheless, GPS observations which are obtained in the situation sometimes have better quality (e.g. Precision or accuracy) than positional information from the place recognition because those coordinates always have some errors. We apply both of observations to a mobile robot localization for the sake of achieving robust localization. Moreover sequential appearance-based place recognition makes it possible to recognize their own position even when we navigate a robot at night. Our system uses not only multiple observations but also dead reckoning with the gyrodometry model. Our experiments are performed over aggregate 5300 m trajectory approximately that contains three times trials through a 1600 m outdoor route in different seasons and at different times, and once trail through a 500 m short-range route to verify its validity.