GPS/self-contained combination type navigation system

A global positioning system (GPS)/self-contained combination type navigation system for a moving object comprising:

• self-contained type positioning means for acquiring self-contained positioning information of the moving object;
• GPS type positioning means for acquiring GPS type positioning information from GPS navigation data transmitted from a plurality of satellites arranged for constituting the global positioning navigation system;
• correcting means for producing a correction signal to be supplied to the self-contained type positioning means based upon the GPS type positioning information, whereby corrected self-contained type positioning information is derived from the self-contained type positioning means;
• present-position determining means for determining a present position of the moving object by processing only one of said corrected self-contained type positioning information and GPS type positioning information, depending upon a reception condition of said GPS positioning information;
• wherein said present-position determining means determines the present position of the moving object by processing said self-contained type positioning information and by replacing said self-contained type positioning information by said GPS type positioning information only when receiving the GPS navigation data simultaneously transmitted from at least three satellites.

A global positioning system (GPS/self-contained combination type navigation system for a vehicle comprising:

• GPS type positioning means for acquiring GPS type positioning information from GPS navigation data transmitted from a plurality of satellites arranged for constituting the global positioning navigation system;
• self-contained type positioning means for acquiring self-contained type positioning information of the vehicle;
• positioning-data processing means for processing both the GPS type positioning information from the GPS type positioning means and the self-contained type positioning information from the self-contained type positioning means so as to obtain GPS type velocity data and self-contained type velocity data, respectively;
• first memory means for temporarily storing the GPS type velocity data derived from the positioning-data processing means;
• second memory means for temporarily storing the self-contained type velocity data derived from the positioning-data processing means;
• comparing means for comparing said GPS type velocity-data read out from the first memory means with said self-contained type velocity-data read out from the second memory means thereby to obtain velocity comparison data;
• present-position determining means for processing one of said GPS type velocity data and self-contained type velocity data so as to determine a present position of the vehicle by judging whether or not the velocity comparison data exceeds a threshold velocity;
• map data memory means for previously storing map data required for navigating the vehicle;
• and,
• display means for displaying the present position of the vehicle superimposed on the map data by receiving the output of the present-position determining means and the map data from the map data memory means,
• wherein said positioning-data processing means further processes both GPS type velocity data and self-contained type velocity data so as to obtain GPS type acceleration data and self-contained type acceleration data, respectively;
• said comparing means further comparing said GPS type acceleration data with said self-contained type acceleration data thereby to obtain acceleration comparison data;
• said present-position determining means further processing one of said GPS type acceleration data and GPS type acceleration data so as to determine the present position of the vehicle by judging whether or not the acceleration comparison data exceeds threshold acceleration.