NAVIGATION DEVICE AND ALERTING METHOD THEREOF

The present invention discloses a navigation device and the alerting method thereof. The alerting method of the navigation device comprises (a) determining a current location and a destination and displaying corresponding map information; (b) planning possible routes by computing cost of each possible route, selecting the minimum cost route as the optimized route among the possible routes, regarding other possible routes having a relatively higher cost as deviation routes; (c) computing a turning cost for each deviation route, wherein the turning cost represents cost difference between each deviation route and the optimized route respectively in an upcoming intersection, on which the possible routes are branched; (d) at a prompter location issuing a voice guidance about how to follow the optimized route, wherein if the upcoming intersection has a turning cost greater than a warning threshold, then the upcoming intersection is a decision point, and additional alertness is issued before the upcoming intersection.