A navigation system having two sensors and two circuits. A travel sensor sends a pulse whenever a vehicle travels a predetermined distance. An angular velocity sensor outputs a voltage corresponding to an angular velocity of the vehicle. A correction circuit calculates the angular velocity from both a reference voltage that corresponds to an angular velocity of zero and an output voltage from the angular velocity sensor. A reference voltage resetting circuit monitors the pulse from the travel sensor; sets, as an effective sampling interval, at least a part of a interval from the end of a predetermined first cancellation interval after the pulse stops until the start of a second cancellation interval prior to a resumption of the pulse; calculates an average value of the output voltage of the angular velocity sensor, which has been periodically sampled during the effective sampling interval; and resets the reference voltage to the average value.
A method of detecting an angle is provided with processes of: setting a bias voltage, as a standard voltage, which is an output voltage outputted from an angular velocity sensor (12) under a predetermined condition; and calculating the angle on the basis of a difference between the output voltage and the set or updated standard voltage. It is further provided with processes of storing time data, which indicate a time of setting or updating the standard voltage, in correspondence with standard voltage data; estimating a value of the bias voltage of the angular velocity sensor at each time between times of setting or updating the standard voltage; and correcting the calculated angle on the basis of a difference between a value of the standard voltage used in the calculation process and the estimated value of the bias voltage.
A technique for determining a gyro zero voltage is provided. A gyroscope ("gyro") is installed in an automobile as a component of an on-board navigation system. The gyro outputs a voltage representing an angular velocity of the vehicle. The gyro output voltage representing zero angular velocity ("gyro zero voltage") is determined by first determining when the vehicle is stationary based upon the amount of noise in the output voltage of the gyro. When the vehicle is determined to be stationary, the gyro zero voltage is measured.
A system for identifying a fastest possible travel route is disclosed. A traveler data processor collects traffic speed data and associates the traffic speed data with road segments. The road segments collectively represent one or more possible travel routes from a start point to an end point. A forecast engine determines a predicted travel time for each of the road segments based on, for example, the traffic speed data for each of the road segments. A routing engine determines the fastest possible travel route from the start point to the end point. The fastest possible travel route is the possible travel route from the one or more possible travel routes with the shortest predicted travel time.
A system for predicting a travel time for a traffic route is disclosed. The traffic route comprises one or more road segments. A predicted travel time for each of those segments is calculated based, in part, on traffic speed data for each of the one or more road segments. A total travel time is then calculated for the route, the total travel time including a predicted travel time for each of the one or more road segments.
Disclosed herein is a traveler information monitoring and dissemination system. The system disclosed herein provides real time information to a traveler, wherein the real time information may be pre-selected by the traveler. The system ensures consistent and quality data are produced and issued to the traveler.
