Navigation system and controlling method for the motor vehicle

A navigation system for use in a mobile object, comprising:

• a transceiver unit for transmitting a signal for demanding a detection of a navigation path, which is a short-cut path or an optimum path from a departure point to a destination, to a path detecting server via a wireless network and then receiving path data which represents the navigation path from the path detecting server via the wireless network;
• a display unit for outputting the navigation path or a revised navigation path;
• an input unit for inputting data on the departure point and the destination;
• and
• an electronic control unit (ECU) for transferring the data on the departure point and the destination from the input unit to the transceiver unit, transferring the path data from the transceiver unit to the display unit, precalculating deviation-expected path data which represent one or more deviation-expected paths in the course of driving along the navigation path, storing the one or more deviation-expected paths in a memory of the navigation system installed in the mobile object before the mobile object deviates from the navigation path, and selecting revised path data which represent the revised navigation path, among the one or more precalculated deviation-expected paths stored in the memory to thereby provide the revised navigation path to the display unit after a present position of the mobile object deviates from the navigation path,
• wherein the one or more deviation-expected paths are precalculated based on nodes and links connecting the nodes between the departure point and the destination.