Navigation system with off-route detection and route recalculation

• US 5,262,775 A
• Filed: 04/07/1992
• Issued: 11/16/1993
• Est. Priority Date: 04/07/1992
• Status: Expired due to Term

• Current Assignee: TomTom International BV (TomTom NV)
• Original Assignee: Zexel Corporation
• Inventors: Abe, Tatsuhiko, Tamai, Haruhisa
• Primary Examiner(s): Swarthout, Brent
• Application Number:
  US07/864,515
• Time in Patent Office: 588 Days
• Field of Search: 340/990, 340/995, 340/988, 73/178 R, 364/449, 364/444
• US Class Current: 340/995.21
• CPC Class Codes: G01C 21/3415 Dynamic re-routing, e.g. recalculating the route when the user deviates from calculated route or after detecting real-time traffic data or accidents

Abstract

Where a vehicle deviates from a calculated optimal route, the system displays a message indicating the vehicle'"'"'s deviation. The driver of the vehicle commands computation of a new optimum route. The system selects a new starting point from a point substantially ahead of the vehicle, recomputes the optimal route, and determines the route from the new starting point to the destination. The new starting point is far enough ahead of the vehicle to ensure that the route computation is completed before the vehicle reaches it. This prevents overrunning the new starting point before the calculation of a new optimum route is completed. Navigation guidance, computed for the new optimal route, is then displayed.

Claims

1. A vehicle navigation system, which comprises:

means for storing and retrieving a plurality of map data;

a shaft sensor;

a terrestrial magnetism sensor;

said shaft sensor and said terrestrial magnetism sensor cooperating to detect a present location of a vehicle;

a microcomputer for computing from said map data an optimal route for said vehicle from a starting point to a destination;

said shaft sensor, said terrestrial magnetism sensor, and said microcomputer cooperating to detect a deviation of said vehicle from said optimal route;

a display disposed to convey information that said vehicle has deviated from said optimal route;

means for commanding computation of a route;

said means for storing and retrieving and said microcomputer cooperating, in response to said means for commanding, to determine a geographic point separated a predetermined distance from said vehicle'"'"'s present location and ahead of said vehicle;

said geographic point providing a new starting point for a calculation of a new optimal route; and

said microcomputer communicating navigation guidance to said display for presentation thereon.

2. A vehicle navigation system according to claim 1, wherein said means for storing and retrieving includes a CD ROM.

3. A vehicle navigation system according to claim 1, wherein said means for storing and retrieving includes an IC card.

4. A vehicle navigation system according to claim 1, wherein said means for commanding includes a touch screen switch.

5. A vehicle navigation system according to claim 1, wherein said display includes a CRT.

6. A vehicle navigation system according to claim 1, wherein said display includes an LCD.

7. Apparatus according to claim 1, wherein said predetermined distance is sufficient, for a present speed of said vehicle, to permit completion of computation of said new optimum route before said geographic point is reached, whereby said vehicle will not overrun said geographic point before said completion of computation.