Navigation system with capability of instructing running direction

• US 4,679,147 A
• Filed: 03/25/1985
• Issued: 07/07/1987
• Est. Priority Date: 03/28/1984
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Shibata, Takanori, Endo, Akira, Shirai, Hiroshi, Matsuoka, Yoji, Tsujii, Fumio
• Primary Examiner(s): Chin, Gary
• Application Number:
  US06/715,259
• Time in Patent Office: 834 Days
• Field of Search: 364/424, 364/443, 364/449, 364/460, 364/521, 73/178 R, 343/451, 340/988, 340/990, 340/995, 342/451
• US Class Current: 701/211
• CPC Class Codes: G01C 21/3629 Guidance using speech or audio output, e.g. text-to-speech text to speech systems per se G10L13/00
• CPC Class Codes: G01C 21/3667 Display of a road map G01C21/3614 takes precedence; guidance using 3D or perspective road maps G01C21/3635

Abstract

A navigation system for displaying, on a display screen, road map information and running traces of a car superimposed thereon comprises a cathode ray tube for displaying the road map information and information regarding the car running traces and the like, bearing sensors for detecting a running direction of the car, a detector for detecting a running distance of the car by detecting a revolution of the car wheel, and a controller receiving outputs from the bearing sensors and the running distance detector, for computing a current position of the car and selecting road map information corresponding to the current position for display thereof on the cathode ray tube. The controller sets specified circular areas centered on respective crossings on the road map information, detects arrival of the car at an entrance to a specified area, determines an angular difference between an approaching running direction of the car and a destination bearing at the entrance, and gives, on the basis of the determined angular difference, a voice instruction for running of the car at the crossing to the driver.

Claims

1. A navigation system for displaying, on a display screen, road map information and a running trace of a car superimposed thereon comprising:

display means including a cathode ray tube for displaying road map information and information regarding the car running trace;

at least one bearing sensor means for detecting the running direction of the car;

running distance detector means for detecting the running distance of the car; and

control means, connected to receive output signals from said bearing sensor means and said running distance detector means, for computing a current position of the car, for controlling car running information. such as the road map information, a running trace and a running bearing corresponding to the current position of the car, and for displaying the car running information on said cathode ray tube,

said control means including;

(a) external storage means for storing the road map information and the car running information;

(b) a central control unit for controlling said external storage means, said computation of the current position of the car and said display of the road map information; and

(c) means for instructing the driver as to the desired running direction; and

wherein;

said central control unit comprises means for setting specified areas centered on respective crossings of roads on said road map information stored in said external storage means, means for calculating a running position of the car in accordance with the output signals of said bearing sensor means and said running distance detector means, means for detecting the arrival of the car at an entrance of the specified area by comparing the calculated value of the running position with data indicating the boundary of the specified area, means for determining the angular difference between the current running direction of the car and a destination bearing at the entrance of the specified area in accordance with the output signal of said bearing sensor means at said entrance and information of the destination bearing stored in said external storage means, and means for controlling said running direction instructing means to indicate to the driver the desired running direction at a crossing in accordance with said determined angular difference.

2. A navigation system according to claim 1, wherein said running direction instructing means provides a voice instruction to the driver.

3. A navigation system according to claim 2, wherein said running direction instructing means comprises a loudspeaker for issuing a voice instruction.

4. A navigation system according to claim 1, wherein said means for determining the angular difference between the current running direction of the car and the destination bearing referenced to the destination controls said running direction instructing means to indicate a straightforward running when the angular difference falls within ±

30°

.

5. A navigation system according to claim 4, wherein said running direction instructing means is controlled to indicate a turn-to-the left running when the angular difference falls within a range of from 30°

to 180°

, and said running direction instructing means is controlled to indicate a turn-to-the right running when the angular difference falls within a range of from 180°

to 330°

.

6. A navigation system according to claim 1, wherein said specified area is centered on said crossing and has its boundary spaced a predetermined distance from said crossing, the data defining said area by the boundary being stored in said external storage means.

7. A navigation system according to claim 6, wherein the boundary of said specified area is spaced by 50 m from said crossing.