Calculation of estimated time of arrival (eta) based on thoroughfare

Abstract

A portable electronic navigational aid device and method calculates estimated time en route and estimated time of arrival. A user inputs a plurality of variables, including identity, cartographic data, final destination. Upon receiving the inputs, the device determines from cartographic data the estimated distance to the final destination and the type of thoroughfare the inputted trip will traverse. During operation, the device recalls the average driving velocity for the inputted driver over each different type of thoroughfare traversed. Using prestored average velocity data, the device calculates an initial estimated time en route and an estimated time of arrival for a desired route. The device continues to receive GPS data as to the driver's position and velocity and updates the average velocity record for that driver on the specific type of thoroughfare. As the average velocity fluctuates, the device adjusts the estimated time en route and the estimated time of arrival. The device further has control processes for potentially erroneous sampling. The device has a predetermined threshold in which data inputs below that threshold will not be averaged into the memory. The second control process of the present invention allows for zero velocity sampling without necessitating a reset of the entire system. If the device samples a zero speed, it will not average that velocity into the system as explained above. Rather, a stop time measured by a counter will be added to the estimated time en route and estimated time to arrival.