k-pos follow target mode

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Kongsberg K-PosFollow Target Mode

Operator Manual Release 7.0

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October 2006


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Document history

Document number: 301040

Rev. A October 2006 This version describes operation of the Follow Target mode of

the K-Pos system at K-Pos basis software release 7.0.

The reader

This operator manual is intended as a reference manual for the system operator. This manual is based onthe assumption that the system operator is an experienced DP operator with a good understanding of basicDP principles and general DP operation. If this is not the case, then the operator should first attend theappropriate Kongsberg Maritime training courses.

Note

The information contained in this document remains the sole property of Kongsberg Maritime AS. No part of this document may be copied or reproduced in any form or by any means, and the informationcontained within it is not to be communicated to a third party, without the prior written consent of

Kongsberg Maritime AS. Kongsberg Maritime AS endeavours to ensure that all information in this document is correct and fairly stated, but does not accept liability for any errors or omissions.

Warning

The equipment to which this manual applies must only be used for th e purpose for which it wasdesigned. Improper use or maintenance may cause damage to the equipment and/or injury to personnel.The user must be familiar with the contents of the appropriate manuals before attempting to operateor work on the equipment.

Kongsberg Maritime disclaims any responsibility for damage or injury caused by improper installation,use or maintenance of the equipment.

Comments

To assist us in making improvements to the product and to this manual, we welcome comments andconstructive criticism.e-mail: [email protected]

P.O.Box 483N-3601 Kongsberg,

Norway

Kongsberg Maritime AS

Telephone: +47 32 28 50 00Telefax: +47 32 28 50 10

Service: +47 815 35 355

www.kongsberg.com


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Operator Manual

Table of contents

1 FOLLOW TARGET MODE .................................................... 5

2 FOLLOW SINGLE MOBILE TARGET..................................... 7

3 MULTI TARGETING............................................................ 7

4 ENTERING FOLLOW TARGET MODE ................................. 10

5 CORRUPTED TRANSPONDER SIGNALS ............................ 13

6 HEADING CONTROL ........................................................ 13

7 POSITION CONTROL ....................................................... 13

8 SPEED CONTROL ............................................................. 139 ACCELERATION............................................................... 14

10 RATE OF TURN ................................................................ 14

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1 FOLLOW TARGET MODEA K-Pos system with Follow Target mode has one of twoavailable configurations:

• Follow Single Mobile Target

• Follow Multiple Mobile Targets

Follow Single Mobile Target enables the vessel to automaticallyfollow a moving target and keeps the vessel within a “positionwindow” relative to the target. The moving target must beequipped with a mobile reference transponder or laser reflector in order for the K-Pos system to monitor its relative position. If,for example, the moving target is a Remotely Operated Vehicle,

then the vessel must be equipped with a Hydroacoustic PositionReference (HPR) system.

In addition to a mobile reference transponder on the target, anadditional fixed position-reference system is required, such asDGPS or a fixed transponder deployed on the seabed.

You can define a circle of operation within which the target canmove without causing the vessel to move. The vessel only moveswhen the target reaches the boundary of this circle. The radius of this circle (the “reaction radius”) can be up to 1000 m.

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Figure 1 Follow Single Target

Follow Multiple Mobile Targets enables a DP vessel to follow amoving structure or vessel equipped with two or more targets(such as laser reflectors). For example, a Fanbeam positionreference system with software for dual target can typically beused. The moving structure can be followed both with respectto position and heading.

The operator can select between the following operational modes:

• Follow Position, makes the vessel follow the moving structurewith respect to position. The vessel will always have the same

position relative to the moving structure, while maintainingthe absolute heading.

• Follow Heading , makes the vessel follow the moving structurewith respect to heading. The vessel will always have the sameheading relative to the moving structure, while maintainingthe absolute position.

• Follow Position and Heading , makes the vessel follow themoving structure with respect to both position and heading.

The vessel will always have the same position and headingrelative to the moving structure.

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2 FOLLOW SINGLE MOBILE TARGETThis section describes the Follow Target dialog box in a K-Possystem that has the Follow Single Mobile Target configuration.

To display the Follow Target dialog box, click AutoPos→FollowTarget.

Mobile Targets

To select a transponder, in the Available list, highlight the requiredtransponder and click Add. To remove a transponder from theSelected list, highlight the transponder you want to remove andclick Rem. Only one transponder can be selected at a time.

Reaction Limits

Position

Defines the reaction limit for position (reaction circle). The valueentered (between 0 and 1000 m) is the radius of the reactioncircle for the mobile target.

Position Filter

Filter constant

Enter the required filter constant (0 to 100%) to increase or decrease the degree of position filtering. A high percentage (50to 100%) gives a high filtering which is recommended if there isnoise or unstable measurements from the transponders. A low

percentage (0 to 50%) gives a low filtering which should be usedif measurements from the transponders are stable and reliable.

3 MULTI TARGETING

This section describes the Follow Target dialog box in a K-Possystem that has the Follow Multiple Mobile Targets configuration.

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Follow Target Mode

To display the Follow Target dialog box, select AutoPos→FollowTarget

Mobile Targets

To select a transponder, in the Available list, highlight the requiredtransponder and click Add. To remove a transponder from theSelected list, highlight the transponder you want to remove andclick Rem.

Operation mode

Follow Position

Choose this to make the vessel follow the moving structure

with respect to position. The vessel will always have the same position relative to the moving structure, while maintaining thesame absolute heading (setpoint) as shown in the followingillustration. At least one transponder must be selected for thisoption to be available.

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Follow Heading

Choose this to make the vessel follow the moving structure withrespect to heading. The vessel will always have the same heading

relative to the moving structure, while maintaining the sameabsolute position as shown in the following illustration. At leasttwo transponders must be selected for this option to be available.

Follow Position and Heading

Choose this to make the vessel follow the moving structure withrespect to both position and heading. The vessel will always havethe same position and heading relative to the moving structureas shown in the following illustration. At least two transpondersmust be selected for this option to be available.

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Follow Target Mode

Reaction Limits

Position

Defines the reaction limit for position (reaction circle). The valueentered (between 0 and 1000m) is the radius of the reaction circlefor the mobile target.

Heading

Defines the vessel’s reaction sector for the heading relative to themoving structure.

Position Filter

Filter constant

Enter the required filter constant (0-100%) to increase or decrease the degree of position filtering. A high percentage(50-100%) gives a high filtering which is recommended if thereis noise or unstable measurements from the transponders. A low

percentage (0-50%) gives a low filtering which should be used if measurements from the transponders are stable and reliable.

4 ENTERING FOLLOW TARGET MODEYou can enter the Follow Target mode from either the Joystick or Auto Position mode.

1 Enable a fixed position-reference system as the reference

origin (see the Position Information chapter in the relevant K-Pos (OS) Operator Manual ).

2 Select Sensors→Reference System Settings.

• The Reference System Settings dialog box is displayed.

a Enable the transponder(s) on the target to be tracked.

b Check the Mobile check box for the transponder if necessary.

3 Select AutoPos →Follow Target.

• The Follow Target dialog box is displayed.

a In the Available list, highlight the mobile transponder you wish to use and click the Add button to select it.

b When using Follow Multiple Mobile Targets, selectthe required Operation mode.

c Set the required Reaction limits and Position Filtervalues.

d Click the Apply button to use the values entered inthe Follow Target dialog box.

4 Press the FOLLOW TARGET mode button twice.

• The FOLLOW TARGET

status lamp is lit.• The SURGE, SWAY and YAW status lamps are lit.

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• The reaction radius is displayed on the Posplot viewas a circle around the filtered position(s) of the mobile

transponder(s). For Follow Single Mobile Target, seeFigure 2. For Follow Multiple Mobile Targets see Figure3.

• Follow Single Mobile Target:

Figure 2 Posplot view in Follow Single Mobile Target mode

As the mobile transponder moves, the vessel’s position

setpoint remains unchanged.When the mobile transponder reaches the edge of its reactionradius circle, the position setpoint is updated automatically torestore the vessel to the same position relative to the target,and the reaction radius circle is redrawn around the new

position of the mobile transponder.

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• Follow Multiple Mobile Targets:

As the mobile transponders move, the vessel’s

position/heading setpoint(s) remain(s) unchanged.

When one of the mobile transponders reaches the edgeof its reaction radius circle, the position setpoint isupdated automatically to restore the vessel to the same

position/heading relative to the targets, and the reaction radiuscircles are redrawn around the new positions of all the mobiletransponders.

Figure 3 Posplot view in Multi Target mode

When the Follow Heading operational mode is selected in Follow Multiple Moving Targets mode, a Target Deviation presentationis given in the General view, see Figure 4. The lines indicate alimit where a heading change will be initiated.

Figure 4 Target Deviation presentation in General view

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5 CORRUPTED TRANSPONDER SIGNALSIt may occur that the signals from the target transponders arecorrupted. To avoid a sudden change in the vessel’s positionsetpoint because of unstable measurements, a position setpoint

jump test is performed. If the distance between the previous position and the new position is longer than a predefined limit, itis assumed that the change is caused by unstable measurents (no“real” position change).

The vessel maintains its present position and the followingwarning message is displayed.

Follow target relative angle rejected

In this event the operational advice is as follows:• Take the K-Pos system to Auto Position mode to reset the

Follow Target function.

• Consider using other target transponders and increasing thereaction limits.

6 HEADING CONTROLAll of the standard methods for heading control are available asdescribed in the Changing the Heading Setpoint chapter of the

relevant K-Pos (OS) Operator Manual .

In the Follow Target mode, choosing System Selected headingfrom the Change Heading dialog box will maintain the vesselat the heading that requires the minimum power in the currentenvironmental conditions.

System Selected heading is not available in Follow Multiple Mobile Targets mode when Follow Heading or Follow Positionand Heading is selected.

7 POSITION CONTROLWhen in Follow Target mode, you can change the distance tothe target whenever necessary. All of the standard methods for

position control are available as described in the Changing the Position Setpoint chapter of the relevant K-Pos (OS) Operator Manual .

8 SPEED CONTROLSee Speed Setpoint dialog box and the Speed page of the Position

dialog box in the Changing the Position Setpoint chapter of therelevant K-Pos (OS) Operator Manual for more information.

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9 ACCELERATIONSee Acceleration/Retardation Settings dialog box in the Changing the Position Setpoint and Changing the Heading Setpoint chapters of the relevant K-Pos (OS) Operator Manual for moreinformation.

10 RATE OF TURNSee Rate Of Turn page of the Heading dialog box in the Changing the Heading Setpoint chapter of the relevant K-Pos (OS)Operator Manual for more information.

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©2006 Kongsberg Maritime

P.O.Box 483N-3601 Kongsberg,

Norway

Kongsberg Maritime AS

Telephone: +47 32 28 50 00Telefax: +47 32 28 50 10

Service: +47 815 35 355

www.kongsberg.com

k-pos follow target mode

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