Abstract: The improved vehicle navigation system and method uses information from a Global Positioning System (GPS) to obtain velocity vectors, which include speed and heading components, for propagating or "dead reckoning" the vehicle position from a previous position to a current position. The improved vehicle navigation system has a GPS receiver which provides the GPS velocity information which is calculated from a full set of GPS delta range measurements. GPS position data alone is not accurate enough for certain applications, such as turn-by-turn route guidance in automobile applications, because its error may be 100 m and there is considerable position drift, even when stationary. GPS velocities are much more accurate than the position data, 1 m/s or thereabouts, and can be used to propagate a known position forward and be more accurate over time than the GPS position solution. These velocities are instantaneous and not those computed from differencing two positions.

Abstract: A navigation simulator and recorder includes a computer and several position and attitude determining devices installed in a vehicle driven along a test route. The data from the position and attitude determining devices is stored in the computer while the vehicle is driven along the test route. The recorded data from the test drive is subsequently utilized to test a navigation system. The output of the navigation system under test is monitored to determine its response to the real time recorded data.

Abstract: A navigation system permits the user to designate certain roads or areas to avoid when planning a route. The navigation system generally includes a database of road segments and a cost associated with the road segments, such as estimated time of travel across that road segment and estimated length of travel across that road segment. The navigation system determines a route from a selected beginning point to a desired destination by evaluating the cost of the road segments to be traveled in several potential routes and recommends the potential route having the lowest total cost. The user can selectively modify the cost of selected road segments to indicate a preference or avoidance of such roads. By increasing the cost of a road segment, the navigation system is less likely to recommend a potential route which includes that road segment. Similarly, by decreasing the cost of a selected road segment, the navigation system is more likely to recommend a potential route which includes that road segment.

Abstract: The improved vehicle navigation system and method uses information from a Global Positioning System (GPS) to obtain velocity vectors, which include speed and heading components, for "dead reckoning" the vehicle position from a previous position. If information from the GPS is not available, then the improved vehicle navigation system uses information from an orthogonal axes accelerometer, such as two or three orthogonally positioned accelerometers, to propagate vehicle position. Because the GPS information should almost always be available, the improved vehicle navigation system relies less on its accelerometers, thereby allowing the use of less expensive accelerometers. The improved vehicle navigation system retains the accuracy of the accelerometers by repeatedly calibrating them with the velocity data obtained from the GPS information. The improved vehicle navigation system calibrates the sensors whenever GPS data is available (for example, once a second at relatively high speeds).

Abstract: The navigation system has a display for displaying vehicle service reminders and an input device to permit the driver to define vehicle service intervals. A wheel speed sensor continuously inputs distance data into a CPU. A GPS system receiver continuously inputs date and time data into the CPU. The CPU compares the time and distance data to user defined vehicle service intervals. When the time or distance have exceeded the user defined vehicle service intervals, the CPU generates a vehicle service reminder on the display. The driver can then request the navigation system to guide the driver to an appropriate vehicle service location.