Recognition of vehicle's location for navigation

Abstract

Vigorous research and development o n v e h i c l e n a v i g a t i o n has b e e n underway f o r s o m e years . Essential for a navigation system is the a b i l i t y t o r e c o g n i z e t h e l o c a t i o n o f a c a r accurately . Without that ability , i t would be useless t o provide detailed road map inforniation , r o a d and traffic i n f o r m a t i o n ( traffic j a m s , c l o s e d -r o a d , traffic accidents , etc. ) , and p a r k i n g s p a c e a v a i l a b i l i t y --in d e v e l o p m e n t u n d e r a J a p a n e s e p r o j e c t of ' R o a d / A u t o m o b i l e Communication System ' _ T h e m e t h o d s t o f i n d c a r ' s l o c a t i o n c a n b e classified into two groups ' dead-reckoning and r a d i o n a v i g a t i o n . T h e d e a d -r e c k o n i n g system c a l c u l a t e s c a r ' s l o c a t i o n a c c o r d i n g to i t s direction and distance travelled .This method is advantageous in that there is no areal limitation for its o p e r a t i o n . But i t cannot be free from errors which increase a s the car accumulates the distance , making i t necessary to set the initial position . On the other hand, the radio navigation system pinpoints the location of a car in terms of absolute position through radio waves and has an a d v a n t a g e o f a l w a y s l o c a t i n g a car w i t h i n the system's accuracy range . But this system requires a v a s t n e t w o r k o f r a d i o t r a n s m i t t e r s t o b e effective , and i t can only operate in the areas covered by the system network . Dead-reckoning is basis for car locating but w i l l no purpose without some provision for automatic c o r r e c t i o n o f its e r r o r s . Radio navigation is expected to give accurate location . although i t w o u l d h a v e d i f f i c u l t y in p r o v i d i n g a c c u r a t e l o c a t i o n c o n t i n u o u s l y . I t s e e m s by c o m b i n i n g t h e s e t w o m e t h o d s t h a t a s y s t e m c a p a b l e o f accurate and continuous car location will become a reality . T h i s paper d e s c r i b e s the signpost navigation , map-matching , and satellite navigation a s methods for c o r r e c t i n g the accumulated errors of deadr e c k o n i n g , and m e t h o d s t o obtain accurate and continuous car location by combining those methods and dead-reckoning . Also discussed are the merits /demerits and feasibility of each method , 1. IMPORTANCE OF CAR LOCATING IN VEHICLE NAVIGATION SYSTEMS 1.1 Development Trend of Vehicle Navigation Systems V e h i c l e n a v i g a t i o n s y s t e m s h a v e b e e n u n d e r development for many years . I t was in 1981 that a system offering simple driving information , such a s s t r a i g h t d i s t a n c e t o t h e d e s t i n a t i o n , percentage of distance covered , and direction of t h e d e s t i n a t i o n , was f i r s t c o m m e r c i a l i z e d in Japan . In 1984 , another system was put on sale which offered a compact disc ( CD-ROM ) storing digital map data allowing the driver t o call up a map ...