GB2260210A

GB2260210A - Navigation system

Info

Publication number: GB2260210A
Application number: GB9121091A
Authority: GB
Inventors: Christopher J Woodhouse
Original assignee: Ford Motor Co
Current assignee: Ford Motor Co
Priority date: 1991-10-04
Filing date: 1991-10-04
Publication date: 1993-04-07
Also published as: GB9121091D0

Abstract

A navigation system has a screen for conveying instructions to the driver of a vehicle and processing means for displaying distance and direction data on the screen. The data is graphically represented by an arrow having a shape corresponding to the map of the road between the current vehicle position and the next junction at which a manoeuvre is to take place, the length of the stem of the arrow corresponding to the distance to the junction and the head of the arrow indicating the exit route at the junction. <IMAGE>

Description

NAVIGATION SYSTEM Field of the invention The present invention relates to a navigation system for providing directions to the driver of a motor vehicle.

Background of the invention Navigation systems are already known which operate using a variety of principles to give the driver route guidance. In such a system the driver enters his intended destination before the start of a journey. A computer storing regional navigational data receives signals from navigation equipment indicating the current vehicle location and heading and supplies route guidance using voice and visual directions to indicate the optimum route. The navigation system can determine vehicle location in a number of ways, for example by using satellite navigation or dead reckoning combined with map matching and by logging vehicle velocity. The invention is not directly concerned with how the computer determines the instructions which are to be passed on to the driver but with the user interface which enables the instructions to be understood clearly and intuitively.

The user interface comprises a screen and a loudspeaker, the invention being concerned with the manner in which the information displayed on the screen. While one may simply display a text message such as "Left at the next junction", such a message is easily misunderstood. It has therefore been proposed to use a graphical representation. In particular, it has been suggested to display a simple arrow indicating direction and a bar graph indicating distance to the manoeuvre.

Though this method of displaying instructions is superior to a text based method, the understanding of instructions is still not completely intuitive as the distance and direction information are derived from two essentially separate parts of the displayed image and require individual assimilation.

Summarv of the invention According to the present invention, there is provided a navigation system having a screen for conveying instructions to the driver of a vehicle and processing means for displaying distance and direction data on the screen, wherein the data is graphically represented by an arrow having a shape corresponding vectorially to the map of the road between the current vehicle position and the next junction at which a manoeuvre is to take place, the length of the stem of the arrow corresponding to the distance to the junction and the head of the arrow indicating the exit route at the junction.

Preferably, the display also includes a visually distinguishable representation of other roads between the current vehicle position and the exit route at the next junction.

Though the display may be in the form of a two dimensional map, it assists quick understanding of the instructions to display the arrow in three dimensional form, as though viewing in perspective a solid arrow resting on the road surface ahead of the vehicle.

Brief description of the drawings The invention will now be described further, by way of example, with reference to the accompanying drawings, in which: Figures la to lc show the sequence of displays indicating a left turn, and Figures 2a to 2d show the sequence of displays indicating the taking of the third road off a roundabout.

Detailed description of the preferred embodiment The navigation system provides a route guidance display throughout a manoeuvre at a junction, supplying data beforehand to warn of the approach to the junction, during the manoeuvre and briefly at its conclusion for confirmation. It does not however provide a continuous display as this would be both unnecessary and distracting.

The navigation system includes a voice interface to indicate to the driver that he is approaching a junction at which a decision must be made. From that point on an arrow will be displayed on the screen, the stem of which will continuously change in size as the vehicle approaches the junction.

In Figures la, lb and lc there are shown three screens which are displayed by a navigation system of the preferred embodiment of the present invention before a left turn in a typical town environment in which other road junctions appear before the required turning.

As can be seen from Figure 1, the arrow is shown in three dimensions. During normal driving, the driver is accustomed at interpreting three dimensional information and this form of presentation makes for an intuitive assimilation of the data.

The image does not simply include the exit road of interest but other roads between the current position, as represented by the start of the arrow, and the exit road at the next junction. As will seen from the drawings, as roads are passed, they cease to appear on the display.

To enable the driver to distinguish between the desired route and other roads on the map, it is preferred to use differ colours but different shades or dotted lines may be used in a monochrome display. For example, the road map may be in yellow and the desired route in red. In the drawings, lines of different thickness have been used to distinguish between the road map and the route to be followed.

Figures 2a to 2d show the directions given on the screen to instruct the driver to leave the next roundabout by the third exit. These figures will be readily understood without further explanation but are given to illustrate a further preferred feature of the invention, namely that the arrow does not rotate as the vehicle steers around the roundabout because that tends to cause confusion or even nausea. From the moment the map of a junction appears in the screen until the same junction has been negotiated, the road map remains with fixed orientation and the position of the vehicle along the road is indicated by the advancing start of the stem of the arrow.

A further important feature of the invention is that the arrow is not simply a right or left turn arrow, as suggested in the prior art but is a vector pointing in the direction of travel. This is important at junctions, common on the continent, in which five roads meet at an intersection where only a vector pointing in the desired direction of travel can indicate the route unambiguously.

Claims

1. A navigation system having a screen for conveying instructions to the driver of a vehicle and processing means for displaying distance and direction data on the screen, wherein the data is graphically represented by an arrow having a shape corresponding vectorially to the map of the road between the current vehicle position and the next junction at which a manoeuvre is to take place, the length of the stem of the arrow corresponding to the distance to the junction and the head of the arrow indicating the exit route at the junction.

2. A navigation system as claimed in claim 1, wherein the display also includes a visually distinguishable representation of other roads between the current vehicle position and the exit route at the next junction.

3. A navigation system as claimed in claim 1 or 2, wherein the arrow is displayed in three dimensional form.

4. A navigation system as claimed in any preceding claim, wherein the head of the arrow accurately represents the bearing of the exit route at the junction.

5. A navigation system as claimed in any preceding claim, wherein, if the stem of the arrow is not straight when initially displayed, the arrow does not rotate as the stem becomes progressively shorter with movement of the vehicle towards to the junction.

6. A navigation system displaying graphical data substantially as herein described with reference to and as illustrated in the accompanying drawings.