GB2025722A

GB2025722A - Water-way navigational system

Info

Publication number: GB2025722A
Application number: GB7923806A
Authority: GB
Original assignee: NAVITRONIC AB
Current assignee: NAVITRONIC AB
Priority date: 1978-07-13
Filing date: 1979-07-09
Publication date: 1980-01-23
Also published as: NO792326L; SE7807798L; JPS5533695A; NL7905428A; SE417016B

Abstract

A water-way navigational system comprising on board a vessel a log, a time measuring means, a radar set and a computer system (10). The computer system receives information about velocity and time from the log and time measuring means and thus computes the position of the vessel during its passage along a predetermined route (20). Previously prepared geographical information about predetermined targets in form of map representations of the surroundings of points (P1...) along the route (20) enables the computer system (10) to ascertain when the vessel is at a predetermined distance from one of the said points whereupon the computer system (10) displays a map representation belonging to the last named point together with a superposition of a number of radar echoes from predetermined targets displayed on said map representation whereby the navigation can correct the vessel's position. <IMAGE>

Description

SPECIFICATION Water-way navigational system The present invention concerns a water-way navigational system of the type comprising on board a vessel a log, time measuring means and a radar set.

The object of the invention is to provide a navigational system which using a computer system makes it possible to accurately navigate vessels in narrow waters using a very limited information about the conditions around the route the vessel is to cover. Hereby the requirements as to capacity and data programs for the computer system will be moderate which in turn results in much lower costs and makes the system attractive also for smaller vessels.

The characteristic features for a system according to the present invention will be clear from the attached claims. The invention will be described more in detail with reference to the attached drawings, where Figure 1-is a biock diagram for the system. Figure 2 shows schematically a route laid out for a vessel and with map representations marked, and Figure 3 shows a picture screen with map representation and applied radar echoes.

The block diagram according to Figure 1 comprises a computer system 10 with built-in time measuring means and to this system is connected a gyro compass 11, a log 12, a radar set 13, a cassette device 14 and a picture screen 15.

The computer system 10 will from the log 12 and the gyro compass 11 respectively receive information about the course and the velocity of the vessel and from this information about velocity and time successively be computed the position of the vessel running along a predetermined route.

In the cassette device 14 there is in advance prepared information about map representations of the nearest surroundings of certain predetermined and from each other well separated points along the said route. This information is latent available to the computer system and as the vessel passes the said points on the route the actual map representations will successively be applied to the computer system 10 and displayed on the picture screen 15.

The radar set 13 is arranged to simultaneously with the display of a map representation show a multiple but limited number of radar echoes on the just displayed map representation. By suppression of not wanted radar echoes from the radar set one arrives at a limitation of the requirements of the program volume for the computer system without any decreased precision in the statement of the position. The limitation of the radar echoes is done in connection with the working out of the program from available earlier recorded echo position information.

The navigational system works in the following way. When a position computed by the computer system 10 corresponds to a certain distance from one of the said points Pn on the route to the nearest following point Pn+ 1 on the route the computer system displays the map representation belonging to said following point Pn+1 and the radar set displays simultaneously the radar echoes on the picture screen 15. This map representation and these radar echoes remain on the picture screen 15 until the next map representation and the radar echoes belonging thereto and corresponding to a computed position for the point Pn+2 on the route are displayed on the screen 15.

Control information for the operation of the radar set 13 has been prepared in advance and is available in the computer system. This control information refers to said predetermined and from each other well separated points P1, P2, P3 .... Pn, Pn+1, Pn+2 along the said route and is arranged to be activated point to point as the information about the map representations of the route successively are displayed on the screen 15 by the computer system.

In the computer system velocity and time are integrated and thereby the covered distance is provided and is applied to a compatatorwhich also is fed with the corresponding way information.

When agreement is found channels are opened for the radar information to the picture screen and for the map information from the program.

In Figure 2 the dashed line 20 represents the ideal way for a vessel and the full lines 21 and 22 respectively are the tolerance limits or boundaries between which the vessel must be navigated in order that risk for grounding will not occur with regard to the land formations 23, 24, 25, 26 and 28.

On the route 20 are marked a number of points P1 ....

P8, with the distances between these points being dependent of the distance between the tolerance boundaries 21 and 22. Narrow passages require less distance between the points, see for example the distance between the points P4 and P5, but open waters permit longer distances, see for example the distance between the points P1 and P2 or between P7 and P8.

To the point P1 belongs a map representation defined by the dashed line 27, to the point P2 belongs the map representation defined by the chain line 29, and to the point P7 belongs a map representation defined by the line 30 with cross strokes. For position determination by means of the radar set when the vessel is in or near the point P1 three targets are used lying in the three directions 271,272 and 273. The echoes from other targets are thus suppressed. In the same way there are for the point P2 three targets with the directions 291, 292 and 293, and for the point P7 three targets with the directions 301, 302 and 303.In these cases each of the three after each other following map representations will contain three geographical points or rather small circular areas with centers corresponding to the exact position (reference value) of the point (target) and with peripheries stating the tolerance boundary for how far from the said center the corresponding radar echo (actual value) may occur in order that the vessel may be said to be within given tolerance boundaries in the water-way. In figure 3 there are on the screen 15 shown three such circular areas referenced as 31,32 and 33.

Incoming radar echoes (crosses) are referenced as 311,321 and 331. The vessel is marked as an arrow 34 (reference value). The crosses 311, 321 and 331 are well within the corresponding circle which means that the vessel is well within given tolerance values but not on the ideal route line 20 as the crosses are at a distance from the center of the corresponding circle obiquely down to the right. The helmsman is now able to change the course guided by the deviation on the screen in order to compensate said deviation and he continues to follow the vessel's run.

It is suitable to arrange the system with an indicating means for also giving an audible alarm when a radar echo impinges outside of a target area presented on the map representation.

In order to get a map representation as "clean" as is shown in Figure 3 it is necessary that check information for the radar set 13 is beforehand prepared and is available in the computer system.

This check information is to refer to the said points P1 .... P8 on the route according to Figure 2 and is to be activated point by point as the information concerning map representations for the route successively are displayed on the picture screen 15 by the computer system 10. By this check information the radar set is caused to function only during the short time periods and for the distances that correspond to the beforehand for each point selected targets.

Instead of in the usual way presenting a map of a very great area and let the radar set function more or less continuously the present system will display map representations of only those small parts that are actual in connection with the predetermined points. Hereby is also required a significantly less information amount in the cassette device in which beforehand is recorded the course the vessel is to follow. It is important that there is synchronism between the feeding of the map representations and the run of the vessel along the prescribed route. This is provided for example by starting the cassette device 14 when the vessel comes to the first point among the said predetermined points on the route.

Between the points P3 and P4 in Figure 2 the route shows a sheer. Here it is suitable to have a special program for the radar set so that one for example with the aid of the target 25 will get information as to the distance to the target 25 when one comes nearer and nearer to the point of sheer and so that one also gets information about the situation around the vessel during the sheer itself by having the radar set functioning in such a way that it is not locked to for example only three targets at a time. As soon as the sheer is completed the system goes back to the already described principle with map representations in connection with the radar set.

It is suitable as a complement to the now described water-way navigational system to have course supervision with the aid of which the helmsman can supervise the course during the run between two consecutive points in the stated route.

Hereby the helmsman will be better off in holding the vessel on the proper course.

Claims

1. A navigational aid including an information processing unit, a radar set mounted on a vessel, a timer and a log, so disposed that in use the information processing unit can use information from the timer and from the log to compute the progress of the vessel along a predetermined route, compare the position of the vessel with the distance of predetermined points along the said route and: when the vessel has progressed a predetermined distance from one of the said predetermined points, display stored geographical information about the next consecutively following point along the said route together with corresponding geographical information derived from the said radar set about the actual position of the vessel.

2. A navigational aid according to claim 1 in which the said stored geographical information and the said corresponding geographical information is in the form of distances and directions of predetermined fixed reference points from the said next consecutive following point and from the vessel respectively.

3. A navigational aid according to claim 2 in which the said stored geographical information is stored as three predetermined fixed reference points in each instance.

4. A navigational aid according to claim 2 or claim 3 which includes means to indicate when the difference between the distance and direction of one of the said reference points from the said next consecutive following point and the distance and direction of the same said reference point from the vessel, as ascertained by the radar set, exceeds a predetermined value.

5. A navigational aid according to any of the preceding claims in which the said radar set is activated by the information processing unit when the vehicle has progressed the said predetermined distance, and is then controlled by pre-prepared stored instructions, which instructions are in each instance specific to the said predetermined point along the said route which is the said next consecutive following point in that instance.

6. A navigational aid as described herein with reference to and as illustrated by the accompanying drawings.