Navigation system

• US 5,550,538 A
• Filed: 10/31/1994
• Issued: 08/27/1996
• Est. Priority Date: 07/14/1993
• Status: Expired due to Term

• Current Assignee: Tomtom Global Assets BV (TomTom NV)
• Original Assignee: Zexel Corporation
• Inventors: Abe, Tatsuhiko, Fujii, Takao
• Primary Examiner(s): SWARTHOUT, BRENT
• Application Number:
  US08/331,677
• Time in Patent Office: 666 Days
• Field of Search: 340/990, 340/995, 340/905, 340/988, 340/286.14, 73/178 R, 364/444, 364/449
• 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
• CPC Class Codes: G08G 1/096827 where the route is computed onboard

Abstract

A navigation system mounted on a vehicle computes in advance an optimal route from a starting point to a destination. When the vehicle travels off the optimal route, the navigation system detects an off-route deviation. When an off-route deviation is detected, the system computes a restoration route from the vehicle'"'"'s present position to a selected point on the optimal route and rapidly displays navigational information to guide the vehicle thereto. Thus there is no need for the system to compute a new optimal route from the present position to the destination, and there is no delay in supplying the driver with navigational information.

Claims

1. A navigation system comprising:

means for detecting a present position of a vehicle;

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

first means for selecting a first plurality of marked points on said optimal route;

said first plurality of marked points being used for determining a restoration point between said destination and a deviation point;

off-route detection means for detecting a deviation of said vehicle from said optimal route;

said deviation occurring at said deviation point;

second means for selecting one of said first plurality of marked points disposed between a point at which said deviation occurs and said destination, as a restoration point when said off-route detection means detects said deviation;

said second means for selecting including second computing means for computing an optimal restoration route from a plurality of restoration routes each extending from said present position to one of said first plurality of marked points disposed between a deviation point and said destination; and

said optimal restoration route extending from said present position to said restoration point on said optimal route.

2. A navigation system according to claim 1, wherein said first means for selecting selects said first plurality of marked points from a set consisting essentially of intersections on said optimal route.

3. A navigation system according to claim 1, wherein said first means for selecting selects said first plurality of marked points from a set consisting essentially of predetermined intervals on said optimal route.

4. A navigation system according to claim 1, wherein:

said second selecting means selects as said restoration point a one of said first plurality of marked points that is nearest to said present position.

5. A navigation system, comprising:

means for detecting a present position of a vehicle;

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

first means for selecting a first plurality of marked points on said optimal route;

said first plurality of marked points being used for determining a restoration point between said destination and a deviation point;

off-route detection means for detecting a deviation of said vehicle from said optimal route;

said deviation occurring at said deviation point;

second means for selecting said restoration point from said first plurality of marked points;

second computing means for computing an optimal restoration route from said present position to said restoration point on said optimal route when said off-route detection means detects said deviation;

said second selecting means further selects a second plurality of marked points from said first plurality of marked points, said second plurality of marked points being nearer in a straight distance to said present position than are other members of said first plurality of marked points; and

said second computing means determines an optimal restoration route from a plurality of restoration routes each extending from said present position to each of said second plurality of marked points.

6. A navigation system, comprising:

means for detecting a present position of a vehicle;

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

first means for selecting a first plurality of marked points on said optimal route;

said first plurality of marked points being used for determining a restoration point between said destination and a deviation point;

off-route detection means for detecting a deviation of said vehicle from said optimal route;

said deviation occurring at said deviation point;

second means for selecting said restoration point from said first plurality of marked points;

second computing means for computing an optimal restoration route from said present position to said restoration point on said optimal route when said off-route detection means detects said deviation;

said second selecting means further selects a second plurality of marked points from said first plurality of marked points, said second plurality of marked points comprising all marked points within a specified distance from a one of said first plurality of marked points that is nearest said present position; and

said second computing means determines an optimal restoration route from a plurality of restoration routes each extending from said present position to each of said second plurality of marked points.

7. A navigation system, comprising:

means for detecting a present position of a vehicle;

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

first means for selecting a first plurality of marked points on said optimal route;

said first plurality of marked points being used for determining a restoration point between said destination and a deviation point;

off-route detection means for detecting a deviation of said vehicle from said optimal route;

said deviation occurring at said deviation point;

second means for selecting said restoration point from said first plurality of marked points;

second computing means for computing an optimal restoration route from said present position to said restoration point on said optimal route when said off-route detection means detects said deviation;

said second selecting means further selects a second plurality of marked points from said first plurality of marked points, said second plurality of marked points comprising all marked points within a specified distance from said deviation point; and

said second computing means determines an optimal restoration route from a plurality of restoration routes each extending from said present position to each of said second plurality of marked points.

8. A navigation system comprising:

a microcomputer;

a map information storage medium storing map information;

an axle sensor effective for determining distance traveled by a vehicle;

a directional sensor effective for determining direction of travel of said vehicle;

said microcomputer cooperating with said axle sensor and said directional sensor to determine a present position of said vehicle;

an input device effective for entering a starting point and a destination of said vehicle into said microcomputer;

said microcomputer cooperating with said map information storage medium for computing an optimal route for said vehicle from said starting point to said destination;

said microcomputer being effective for selecting a plurality of marked points on said optimal route;

said microcomputer cooperating with said map information storage medium, said axle sensor, and said directional sensor for detecting a deviation of said vehicle from said optimal route;

said microcomputer being further effective for selecting potential restoration points from ones of said plurality of marked points disposed between a point at which said deviation occurs and said destination;

said microcomputer being further effective for computing, when said deviation of said vehicle from said optimal route is detected, an optimal restoration route from a plurality of restoration routes each extending from said present position to one of said potential restoration points;

said optimal restoration route extending from said present position to a restoration point on said optimal route.

9. A navigation system according to claim 8, wherein said microcomputer selects said plurality of marked points respectively at successive intersections along said optimal route.

10. A navigation system according to claim 8, wherein said microcomputer selects said plurality of marked points at predetermined intervals on said optimal route.

11. A navigation system according to claim 8, wherein, when said deviation of said vehicle from said optimal route is detected, said microcomputer first selects as said restoration point a one of said marked points nearest to said present position and then determines said optimal restoration route from said present position to said restoration point.