Navigation system with off-route detection and route recalculation

• US 5,303,159 A
• Filed: 04/14/1992
• Issued: 04/12/1994
• Est. Priority Date: 04/14/1992
• Status: Expired due to Term

• Current Assignee: TomTom International BV (TomTom NV)
• Original Assignee: Zexel Corporation (Robert Bosch GmbH)
• Inventors: Abe, Tatsuhiko, Tamai, Haruhisa
• Primary Examiner(s): Chin, Gary
• Application Number:
  US07/869,141
• Time in Patent Office: 728 Days
• Field of Search: 364/443, 364/444, 364/449, 73/178 R, 340/988, 340/990, 340/995
• US Class Current: 701/210
• 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

A vehicle navigation system computes an optimal route for a journey. When the system detects that a vehicle has deviated from the optimal route, information that tells the driver of the deviation of the vehicle is displayed. When the driver turns on a recomputation command switch after reading the information, a new optimal route is computed, with the vehicle'"'"'s present location as the new starting point. If the vehicle deviates again after computation of the new optimal route, another new optimal route is automatically recomputed, again with the vehicle'"'"'s present location as the new starting point. The driver is thus freed from having to initiate the recomputation manually.

Claims

1. A vehicle navigation system, which comprises:

means for storing and retrieving map data;

first means for detecting a present location of a vehicle;

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

said means for computing including means for computing local navigation guidance from said map data;

second means for detecting deviation of a position of said vehicle from said optimal route;

first means for determining whether said deviation is a first deviation;

second means for determining whether said deviation is a deviation subsequent to said first deviation;

third means for determining whether said deviation is a deviation subsequent to a recomputation of said optimal route;

means for displaying that said vehicle has deviated from said optimal route;

said means for displaying including means for displaying said local navigation guidance when said first means for determining determines that said deviation is said first deviation;

means for commanding a recomputation from said map data of a new optimal route from a new starting point to said destination;

said new starting point being a new present location as detected by said first means for detecting; and

means for automatically computing, from said map data, said new optimal route from said new starting point to said destination, using, as said new starting point, said new present location as detected by said first means for detecting, when said third means for determining determines that a new deviation has been detected after a command from said means for commanding has caused recomputation of a previous optimal route.

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

3. A vehicle navigation system according to claim 1, wherein said means for computing includes a microcomputer.

4. A vehicle navigation system according to claim 1, wherein said first means for detecting includes in combination a distance sensor and a terrestrial magnetism sensor.

5. A vehicle navigation system according to claim 1, wherein said second means for detecting includes in combination a distance sensor, a terrestrial magnetism sensor, and a microcomputer.

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

7. A vehicle navigation system according to claim 1, wherein said first means for determining includes a microcomputer.

8. A vehicle navigation system according to claim 1, wherein said second means for determining includes a microcomputer.

9. A vehicle navigation system according to claim 1, wherein said third means for determining includes a microcomputer.

10. A vehicle navigation system according to claim 1, wherein said means for displaying includes a CRT.

11. A vehicle navigation system according to claim 1, wherein said means for displaying includes a LCD.

12. A vehicle navigation system, which comprises:

a CD ROM for storing and retrieving a plurality of map data;

a distance sensor;

a terrestrial magnetism sensor;

said distance sensor and said terrestrial magnetism sensor sending signals that make it possible to detect a present location of a vehicle;

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

said microcomputer effective to compute local navigation guidance from said map data;

said microcomputer being effective to detect from said signals a deviation of said vehicle from said original optimal route;

said microcomputer including means for determining whether said deviation is a first deviation;

said microcomputer further including means for determining whether said deviation is a second deviation subsequent to a recomputation of said original optimal route;

a CRT display effective to convey information that said vehicle has deviated from said original optimal route when said microcomputer determines that said deviation is said first deviation;

said CRT display further effective to display said local navigation guidance;

a manually operated recomputation command switch for commanding computation of said original optimal route or a new optimal route;

said recomputation command switch being effective to command said microcomputer to compute, from said map data, said new optimal route from a new starting point to said destination;

said new starting point being a new present location as detected from said signals sent to said microcomputer from said distance sensor and said terrestrial magnetism sensor; and

when said microcomputer determines that said second deviation has been detected after a command from said recomputation command switch has caused recomputation of a previous optimal route, said microcomputer automatically computes, from said map data, said new optimal route from said new starting point to said destination.