Vehicle navigation system with off-road navigation

#This invention relates to vehicle navigation systems and, more specifically, to map images appearing on a navigation system video screen of a display device.

#Vehicle navigation systems typically include a display device with a video display that provides a graphical interface for the user. A main function of the video display is to depict the desired map area and route on which the user's vehicle is travelling. For convenience to the driver, several navigational modes may be provided. For example, an on-highway guidance mode may be provided in which directional arrows, highlighted routes, and/or voice instructions are given to the driver to guide the driver to a preselected destination.

#An off-highway navigational mode has been provided to drivers hen traveling off of the road network provided by the storage device or other media. Once the vehicle is driven to a location without any nearby roads or other reference points it becomes more difficult to convey directions to the driver on how to get to the next destination. To this end, waypoints have been used, which represent a location such as latitude and longitude. The waypoints may be linked together to form a route by which the navigation system may direct the driver to follow. However, even with the use of waypoints and defined routes, providing direction to the driver may result in driver confusion. Therefore, what is needed is a navigation system that clearly conveys directions to a waypoint.

#Other advantages of the present invention can be understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

#FIG. 1 is a schematic view of the vehicle navigation system of the present invention;

#FIG. 2 is a front elevational view of the vehicle navigation system display unit having a video display;

#The navigation system 20 of the present invention is shown schematically in FIG. 1. The navigation system 20 includes a unit 30 having a CPU 22 (Central Processing Unit) connected to a display device 24 and a directional input device 26 attached to the vehicle interior by a bracket 27, or the like. The navigation system 20 further includes a database 28 connected to the CPU 22. The database 28 is a mass media storage device, such as a CD-ROM, hard drive, DVD, RAM, ROM or the like which includes a map of the road system in the area to be traveled by the user. Each road in the database is divided into road segments, each having an associated set of cost values, which indicate the “cost” of traveling that road segment. For example, the cost values may include the length of the road segment, the estimated time to travel the road segment, and the type of road (i.e., highway, secondary road, toll road, one way, etc.). The road segment may be part of the vehicle route or may be a road segment outside the vehicle route.

#The navigation system 20 can, but need not, be installed in a vehicle 21. The navigation system can be used in conjunction with position determining devices, such as a GPS receiver 38 and a multi-axis accelerometer 40. Navigation system 20 could alternatively or additionally include a gyroscope 42, a compass 44, and a wheel speed sensor 46, all connected to the CPU 32 (connections not shown for simplicity). Preferably, a combination of these position determining devices is utilized to assure accurate location.

#The display device 22 may include a speaker 29. FIG. 2 is a perspective view of one disclosed embodiment of the display device 24 and directional input device 26, preferably designed as an integral unit attached to the CPU by connection 25. The display device 24 includes a video display 50, or screen, such as a high resolution LCD or flat panel display. The directional input device 26 includes a multiple of input buttons 78 including preferably, an eight-way button shown generally at 80 and a selection key 86 such as an “Enter” key. Although an eight-way button is shown, it will be realized that other input devices, such as a joystick, mouse or roller ball can be employed. The eight-way button 80 is capable of moving in the direction of any one of the directional arrows 84. Movement of the button 80 in the direction of one of the directional arrows 84 transmits a directional signal.