RD Instruments Cobra-Tac User manual

Cobra-TacTM

Autonomous Navigation and Mapping Console

User's Guide

P/N 956-6000-00 (May 2004)

RD Instruments

Acoustic Doppler Solutions

Table of Contents

1.0 Introduction....................................................................................................................................... 1

1.1 System Description .............................................................................................................................1

1.2 Cobra-Tac Overview ........................................................................................................................2

1.3 Conventions Used in this Manual........................................................................................................4

1.4 Cobra-Tac Care ..................................................................................................................................4

1.4.1 General Handling Guidelines ..............................................................................................................4

1.4.2 Battery Guidelines...............................................................................................................................5

1.4.3 Deployment Guidelines.......................................................................................................................5

2.0 Accuracy............................................................................................................................................ 5

3.0 Definitions ......................................................................................................................................... 7

3.1 Positions .............................................................................................................................................7

3.2 Uploading and Downloading ...............................................................................................................7

3.3 Mission Profile.....................................................................................................................................7

3.3.1 Initial position ......................................................................................................................................8

3.3.2 Magnetic Variation ..............................................................................................................................8

3.3.3 Waypoints ...........................................................................................................................................8

3.3.4 Missions ..............................................................................................................................................8

3.3.5 Event Marks ........................................................................................................................................ 8

4.0 Quick Start Guide ............................................................................................................................. 9

4.1 Preparing for a Dive ..........................................................................................................................10

4.1.1 Turn Cobra-Tac Power On .............................................................................................................11

4.1.2 Set Initial Position and Magnetic Variation ........................................................................................12

4.2 Training Mode ...................................................................................................................................13

4.2.1 Waypoint Navigation Mode ...............................................................................................................14

4.2.2 Grid Navigation Mode .......................................................................................................................16

4.2.3 Mark Navigation Mode ......................................................................................................................18

4.2.4 Survey Navigation Mode...................................................................................................................20

4.2.5 Turn Cobra-Tac Off...........................................................................................................................21

5.0 Cobra-Tac Operation ................................................................................................................... 22

5.1 Using the Control Switches ...............................................................................................................23

5.2 Understanding Cobra-Tac Displays ..................................................................................................24

5.2.1 Diver Navigation Indicator .................................................................................................................24

5.2.2 Pitch and Roll Indicator .....................................................................................................................24

5.2.3 Leg Directional Indicator ...................................................................................................................25

5.2.4 Depth and Altitude ............................................................................................................................25

5.2.5 Low Battery Warning.........................................................................................................................25

5.3 Event Marking Function ....................................................................................................................26

5.4 Home Function..................................................................................................................................26

5.5 Menu Screen.....................................................................................................................................27

5.6 Navigation Menu ...............................................................................................................................27

5.6.1 Set Up Option ...................................................................................................................................28

5.6.2 Waypoint Navigation Option..............................................................................................................29

5.6.3 Grid Navigation Option......................................................................................................................31

5.6.4 Navigating to a Marked Location.......................................................................................................32

5.6.5 Survey Navigation Option .................................................................................................................33

5.7 Utilities Menu ....................................................................................................................................35

5.7.1 Calibrate............................................................................................................................................35

Calibrating the Compass...................................................................................................................35

Calibrating the Depth Indicator..........................................................................................................38

5.7.2 Create Mission Though Waypoint Setup...........................................................................................39

Mission Setup ...................................................................................................................................39

Mission Edit.......................................................................................................................................40

5.7.3 Edit Records .....................................................................................................................................41

Delete Records .................................................................................................................................41

Deleting Missions..............................................................................................................................42

Deleting Event Marks........................................................................................................................42

5.7.4 Battery Health Indicator ....................................................................................................................43

6.0 Preparation and Maintenance ....................................................................................................... 44

6.1 Installing and Removing the Battery .................................................................................................44

6.2 Recharging the Battery .....................................................................................................................45

6.3 Charging Batteries Safely .................................................................................................................46

6.4 Battery Tips.......................................................................................................................................46

6.5 I/O and Power Cable.........................................................................................................................46

6.6 Cleaning............................................................................................................................................48

6.7 Firmware Updates.............................................................................................................................49

6.8 Returning a Cobra-Tac for Service ...................................................................................................50

6.8.1 Domestic Shipments .........................................................................................................................50

6.8.2 International Shipments ....................................................................................................................51

6.9 Spare Parts .......................................................................................................................................52

7.0 Technical Support .......................................................................................................................... 53

8.0 Specifications ................................................................................................................................. 54

9.0 Warranty .......................................................................................................................................... 56

List of Figures

Figure 1. Cobra-Tac Top View ........................................................................................................ 3

Figure 2. Cobra-Tac Side View....................................................................................................... 3

Figure 3. Cobra-Tac Opening Screen ........................................................................................ 22

Figure 4. Diver Navigation Indicator Examples............................................................................. 24

Figure 5. Pitch and Roll Indicator ................................................................................................. 24

Figure 6. Leg Directional Indicator ............................................................................................... 25

Figure 7. Depth and Altitude......................................................................................................... 25

Figure 8. Low Battery Warning ..................................................................................................... 25

Figure 9. Marking a Location........................................................................................................ 26

Figure 10. Menu Screen................................................................................................................. 27

Figure 11. Navigation Menu ........................................................................................................... 27

Figure 12. Set Up Option................................................................................................................ 28

Figure 13. Waypoint Navigation Select Mission Screen ................................................................. 29

Figure 14. Waypoint Navigation Display......................................................................................... 30

Figure 15. Lane Width.................................................................................................................... 31

Figure 16. Grid Navigation Options ................................................................................................ 31

Figure 17. Mark Location................................................................................................................ 32

Figure 18. Navigating to a Marked Location................................................................................... 33

Figure 19. Free Navigation Screen................................................................................................. 34

Figure 20. Utilities Menu ................................................................................................................ 35

Figure 21. Calibrate Menu.............................................................................................................. 35

Figure 22. Compass Calibration Screen......................................................................................... 36

Figure 23. Calibrating the Compass ............................................................................................... 37

Figure 24. Compass Calibration Center of Rotation ....................................................................... 37

Figure 25. Waypoint Setup Menu ................................................................................................... 39

Figure 26. Mission Setup Screen ................................................................................................... 39

Figure 27. Edit Mission screen ....................................................................................................... 40

Figure 28. Edit Records Menu........................................................................................................ 41

Figure 29. Delete Records Screen ................................................................................................. 42

Figure 30. Delete Missions Screen................................................................................................. 42

Figure 31. Delete Events Screen.................................................................................................... 43

Figure 32. Battery Health Screen ................................................................................................... 43

Figure 33. I/O Cable.......................................................................................................................47

Figure 34. Power Cable.................................................................................................................. 48

Figure 35. Cobra-Tac Interconnections .......................................................................................... 49

List of Tables

Table 1: Operator Control Switch Functions................................................................................ 23

Table 2: Spare Parts ................................................................................................................... 52

Table 3: Navigation Specifications .............................................................................................. 54

Table 4: Standard Sensors.......................................................................................................... 54

Table 5: Transducer and Hardware............................................................................................. 54

Table 6: Environmental ............................................................................................................... 55

Table 7: Power............................................................................................................................ 55

NOTES

Cobra-Tac User's Guide

P/N 956-6000-00 (May 2004) page 1

Acoustic Doppler Solutions

Cobra-Tac User's Guide

1.0 Introduction

The Cobra-Tac is a rugged, compact, self-contained autonomous naviga-

tion console used to perform underwater hydrographic and site surveys. A

Doppler Velocity Log (DVL) and fluxgate compass provide positioning

data. Depth and altitude are also measured for navigation and hydrographic

purposes.

Geodetic position data, (supplied from GPS, Loran, GLOASS, etc.) is

manually loaded into Cobra-Tac and becomes the “benchmark” from

which the navigation computer calculates new positions. The Doppler ve-

locity log uses a four-transducer sound head to measure speed and direction

over the seafloor as the diver swims with Cobra-Tac. The Doppler’s input

is received by the navigation computer which calculates position, speed,

heading, and distance to the next programmed way point. The position pro-

vided by the Doppler is a true position over the seafloor and therefore does

not have errors introduced by currents or drift. The error rate in this system

is less than 3 to 5% based on circumstances (see “2.0 Accuracy,” page 5).

All data is recorded and can be downloaded to create charts and maps.

1.1 System Description

In its simplest form, the Cobra-Tac is an instrument that:

• Records bottom bathymetry (topography), and mission data.

• Guides you underwater using a grid navigation system.

• Lets you define the location of markers/waypoints.

• Guides you directly to any defined marker/waypoint.

The Cobra-Tac has a transducer assembly below the display control panel.

The transducer assembly transmits acoustic pulses along four beams. The

Cobra-Tac User's Guide

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transducers receive backscattered sound from the ocean bottom and from

the plankton and small particles that ride the water currents.

Using the Doppler effect and basic trigonometry, the Cobra-Tac measures

its movement over the bottom and also the speed and direction of water cur-

rents at multiple locations in the water column. Using its internal compass

and pressure (depth) sensor, the Cobra-Tac can also provide heading, alti-

tude (above the bottom), and depth (below the surface). An internal re-

corder can store information about reference points, predefined waypoints,

in-situ defined waypoints (markers), and water currents.

A backlit LCD display provides the operator heading, range, depth, and

several other key points of information. Cobra-Tac allows the operator to

mark and record objects, either manmade or natural.

1.2 Cobra-Tac Overview

The Cobra-Tac system consists of a Cobra-Tac unit, cables, and soft-

ware. The addition of a Windows® compatible computer allows for data

playback.

Battery – Cobra-Tac uses a non-hazardous rechargeable NiCad battery.

Operation life is 7 to 8 hours of continuous use. The battery is charged

through an external connector on the battery. The UTILITY menu provides

a battery health indicator in the operators display.

Battery Charger – The Smart Charger is a variable input voltage charger that

automatically adjusts for the input voltage from 100 to 240 volts. Recharge

time is five hours.

Display – A backlit LCD display is used to display all navigation and

configuration screens and control functions.

I/O Cable Connector – A Input/Output (I/O) cable is provided to connect the

Cobra-Tac to a PC or notebook computer for downloading data.

Urethane Face – The urethane face covers the transducer ceramics. Never

set the transducer on a hard surface. The urethane face may be damaged.

Housing – The housing is molded polyurethane. The standard Cobra-Tac

housing allows deployment depths to 90 meters.

Control Switches – There are four (4) operator control switches incorpo-

rated next to the display. These switches are oil-filled momentary push but-

tons that can be easily operated with thick diving gloves.

Thermistor – The Thermistor measures the water temperature.

Pressure Sensor – The pressure sensor measures water pressure (depth).

Cobra-Tac User's Guide

P/N 956-6000-00 (May 2004) page 3

Electronic Compass – The compass bearing is indicated via a flux gate

compass integrated in the system electronics.

Software – CobraWare allows the operator to prepare and edit a mission

profile and upload the profile into the Cobra-Tac. Cobra-Tac is supplied

with the mapping software Surfer. This software allows the user to display,

in a graphical and pictorial sense all the data collected by the Cobra-Tac.

NOTE. For more information on using CobraWare and a short tutorial on

using Surfer, see the CobraWare User’s Guide.

BATTERY

CONTROL

SWITCHES DISPLAY

I/O and POWER

CONNECTOR

Figure 1. Cobra-Tac Top View

BATTERY

LATCH

POWER

CABLE

BATTERY

HANDLE

PRESSURE SENSOR &

THERMI

S

T

OR

URETHANE

FACE

HOUSING

Figure 2. Cobra-Tac Side View

Cobra-Tac User's Guide

page 4 RD Instruments

1.3 Conventions Used in this Manual

A different font will indicate what operator control switch to use: for exam-

ple, SCROLL.

Menus are indicated by bold, all capitals: for example NAVIGATION

menu.

You will find two other visual aids that help you: Notes and Cautions.

NOTE. This paragraph format indicates additional information that may

help you avoid problems or that should be considered in using the

described features.

CAUTION. This paragraph format warns the reader of hazardous

procedures (for example, activities that may cause loss of data or damage to

the Cobra-Tac).

1.4 Cobra-Tac Care

This section contains a list of items you should be aware of every time you

handle, use, or deploy your Cobra-Tac. Please refer to this list often.

1.4.1 General Handling Guidelines

• Never set the Cobra-Tac on a hard or rough surface. The ure-

thane transducer faces may be damaged.

• Always remove the retaining strap on the I/O cable and dummy

plug when disconnecting them. Failure to do so will break the

retainer strap.

• Do not apply any upward force on the I/O connector as the I/O

cable is being disconnected. Stressing the connector may

cause the Cobra-Tac to flood. See “I/O and Power Cable,”

page 46 for details on disconnecting the I/O cable.

• Do not expose the Cobra-Tac to prolonged sunlight. The ure-

thane transducer faces or the LCD display may be damaged.

Cover the unit if it will be exposed to sunlight.

• Do not store the Cobra-Tac in temperatures over 75° C. The ure-

thane faces may be damaged.

• Do not lift or support a Cobra-Tac by the power cable. The con-

nector or cable will break.

• Do not lift or support a Cobra-Tac by the battery handle. The

handle or battery will break.

Cobra-Tac User's Guide

P/N 956-6000-00 (May 2004) page 5

1.4.2 Battery Guidelines

• Charge the battery within an ambient temperature range of 0°C to

45°C. Use the provided battery charger and follow the correct

procedure when charging the battery.

• Use the provided cable for charging the battery pack to ensure the

proper polarity connection. Charging with the polarity reversed

can cause the battery to explode, alkaline electrolyte leakage,

fire, or other undesirable problems.

• Check the condition of the O-rings on the power cable (battery

connector side) and the waterproof cap. These O-rungs must be

kept clean and lightly lubricated with silicone grease. Check the

O-rings for nicks or cuts. Damaged O-rings can cause the bat-

tery to short when wet.

• Replace the waterproof cap (one at each end of the battery) or

power cable after charging. The battery sockets are not wa-

terproof and must be capped when wet.

• Over discharging damages the battery characteristics. Turn the

power off when the Cobra-Tac is not in use.

• Store the battery in a cool, dry location (-20 to 45°C). Charge

stored batteries once every six months.

• Dispose of the used battery properly. Do not throw the battery

into a fire. Disposing a battery in a fire can cause the battery

to rupture.

1.4.3 Deployment Guidelines

• Calibrate the compass whenever the battery is replaced, or when

any ferrous metals are relocated around the Cobra-TacTM hous-

ing. Ferro-magnetic materials affect the compass.

2.0 Accuracy

Several factors affect the accuracy of the Cobra-Tac.

The Setup information must be completed before every dive (see “Set Up

Option,” page 28).

• The Initial Position is the absolute (latitude/longitude) position

that the Cobra-Tac entered the water. Enter the latitude and lon-

gitude as accurately as possible using a Differential GPS or other

device.

Cobra-Tac User's Guide

page 6 RD Instruments

NOTE. The initial position is critical to the accuracy of the Cobra-Tac.

Make sure you are entering the position of the Cobra-Tac where it will

enter the water. For best results, enter/edit the initial position once you

have entered the water using a hand held Differential GPS.

• Local magnetic variation correction can be obtained from charts

of the local area. Enter the magnetic variation for the area as ac-

curately as possible.

If you are losing the bottom, indicated by “BAD” displayed instead of the

depth and altitude, then one or more of the following is possible:

• If there are abrupt depth changes, the Cobra-Tac may have trou-

ble locking on to the rapidly changing depths as you swim. If

you know where the abrupt changes are located, try to swim

slowly over these regions.

• If there is air being pulled below the transducer it may block one

or more of the beams. Try swimming deeper in the water.

• Check if debris has become caught on the transducer faces and is

interfering with the beams.

• The bottom has grass, weeds, brush, or other submerged materi-

als that are disrupting the beams near the bottom: try to swim

slowly over these regions.

• There is a high sediment concentration near the bottom, and there

is not enough contrast between the suspended sediment layer and

the actual bottom to determine the true bottom range. At some

point the sediment concentration can be so high the Cobra-Tac

will not work.

NOTE. If the Cobra-Tac looses the bottom, it will use a water-mass layer

to attempt to continue navigating. Accuracy will depend on environmental

conditions.

NOTE. Good Survey Suggestions:

Swim along a grid (parallel paths).

Swim at a high altitude (far from bottom).

Keep the Cobra-Tac level.

Slow down while marking objects.

Cobra-Tac User's Guide

P/N 956-6000-00 (May 2004) page 7

3.0 Definitions

A diver operates the Cobra-Tac with the buttons and LCD display. It is

done in the water without using the CobraWare software.

A user interacts with the Cobra-Tac through the serial port with a computer

and the CobraWare software.

3.1 Positions

Much of the data stored by Cobra-Tac pertains to its position in the water.

Cobra-Tac and CobraWare use two formats to display positions or accept

positions entered by users.

• An absolute position is a latitude and longitude.

• A relative position (used only for waypoints) is a range and

bearing from the previous position. Range is the straight-line

distance (0 to 4999 meters) from the previous position to the

waypoint. Bearing is the true heading from the previous posi-

tion to the waypoint (0 to 359 degrees).

3.2 Uploading and Downloading

Uploading is the process of transferring files from the computer to the Co-

bra-Tac. Downloading is the process of transferring files and data from the

Cobra-Tac to the computer.

3.3 Mission Profile

A mission profile is the information stored in the Cobra-Tac’s memory.

The mission profile often contains data related to a particular dive, obtained

on a particular date and location.

The mission profile contains

• An initial position

• The magnetic variation at the initial position

• 0 to 9 missions

• 0 to 100 events

The Cobra-Tac and CobraWare can transfer mission profiles back and forth.

On the receiving end, the new mission profile replaces the old.

• The Cobra-Tac always has one mission profile stored in its

memory.

• The CobraWare program always has one mission profile open

when running. Use CobraWare to upload and download mission

profiles.

Cobra-Tac User's Guide

page 8 RD Instruments

3.3.1 Initial position

The initial position is the latitude and longitude where the Cobra-Tac en-

ters the water at the beginning of a dive and begins tracking its position (see

“2.0 Accuracy,” page 5).

3.3.2 Magnetic Variation

The Cobra-Tac’s internal compass records magnetic heading. The magnetic

variation at the location is needed to correct to true heading. Magnetic

variation is declination.

3.3.3 Waypoints

A waypoint is a position in the water that the Cobra-Tac guides a diver to-

ward. An absolute waypoint is a latitude and longitude. A relative way-

point is a range and bearing from the previous position.

3.3.4 Missions

A mission is an underwater course consisting of up to 20 connect-the-dot

waypoints. An absolute mission contains absolute waypoints. A relative

mission contains relative waypoints. All waypoint positions in a mission

must be the same type.

The Cobra-Tac has four modes that allow a diver to navigate underwater in

various ways. Missions are for use in the WAYPOINT NAV mode. In this

mode, a diver starts at an initial position, swims to waypoint 1, and then

waypoint 2, and so on.

Missions are intended to be reusable in many mission profiles. They may

be imported and exported as needed (see the CobraWare User’s Guide).

3.3.5 Event Marks

An event is a latitude, longitude, and label where a diver has noted some-

thing of interest and used the Cobra-Tac to mark the position. The Cobra-

Tac requires the diver to label each event as either “NATURAL” or “MAN

MADE”. All events in Cobra-Tac have one of these two labels. The Co-

braWare program allows other labels (see the CobraWare User’s Guide).

Cobra-Tac User's Guide

P/N 956-6000-00 (May 2004) page 9

4.0 Quick Start Guide

The following guide will help you quickly become familiar with the Cobra-

Tac.

Preparing for a Dive

Use the following steps to prepare the Cobra-Tac for a dive.

• Install battery

• Turn Power On

• Set Initial Position and Magnetic Variation

Training Mode

Use Cobra-Tac’s training mode to learn how to use each navigation mode.

• Waypoint Navigation

• Grid Navigation

• Mark Navigation

• Survey Navigation

Use this area for notes.

Cobra-Tac User's Guide

page 10 RD Instruments

4.1 Preparing for a Dive

Use this section to prepare the Cobra-Tac for a mission.

VISUALLY INSPECT THE COBRA-TA

C

HARDWARE

CHECK ALL NUTS

AND BOLTS

ARE INSTALLED

BATTERY PACK

FRESH BATTERY

INSTALLED

POWER CABLE

AND WATERPROOF

CAP CONNECTED

HOUSING

CHECK FOR

CRACKS

URETHANE

TRANSDUCER FACES

CLEAN AND

CHECK FOR CRACKS

Use this area for notes.

Cobra-Tac User's Guide

P/N 956-6000-00 (May 2004) page 11

4.1.1 Turn Cobra-Tac Power On

Press both upper switches to turn the power on. Select MENU (press the

upper right switch) to go to the main menu.

Use this area for notes.

Cobra-Tac User's Guide

page 12 RD Instruments

4.1.2 Set Initial Position and Magnetic Variation

The SET UP screen is used to set the initial position, magnetic variation,

and turn on/off the record function of the Cobra-Tac’s internal recorder.

NOTE. The SET UP option must be completed before any navigation

function can be started.

a. On the main menu, select NAVIGATION.

b. On the NAVIGATION menu, select SETUP.

c. Use

SCROLL to highlight the field where data needs to be entered.

d. Use SELECT to choose the data for the field selected (0-9 or N-S).

e. Repeat this process from field to field until all information is entered.

Select ACCEPT to save the data. Selecting ACCEPT returns the display

back to the NAVIGATION menu.

SCROLL SELECT

ACCEPT CANCEL

LAT :

LONG :

MAGVAR :

RECORD :

3 2

°

4 3 .0 0 0 0 N

1 1 7

°

1 2 . 0 0 0 0 W

1 5 .0

°

E

Y

NOTE. CobraWare is designed to help you setup the initial position and

magnetic variation. For this quick start guide, practice using only the

Cobra-Tac to enter the information.

Use this area for notes.

Cobra-Tac User's Guide

P/N 956-6000-00 (May 2004) page 13

4.2 Training Mode

Use the training mode to learn how to use the Cobra-Tac’s navigation

modes.

a. On the UTILITY menu, press SCROLL until the BATTERY HEALTH

menu is highlighted. Press SCROLL once more so that no menu is high-

lighted.

b. Press SELECT.

c. Use SCROLL and enter 250 (250 mm/s) for the training speed.

d. Select ACCEPT. You will see TRAINING MODE flashing on the bottom

of the display.

NOTE. To exit the training mode, turn off power to the Cobra-Tac by

pressing both the lower switches for 3 seconds.

NOTE. In the training mode, you do not need to move. The Cobra-Tac will

simulate a constant speed. The heading and tilts are real. It may be

helpful to walk the course in a parking lot.

Use this area for notes.

Cobra-Tac User's Guide

page 14 RD Instruments

4.2.1 Waypoint Navigation Mode

The WAYPOINT NAV option allows a diver to navigate via waypoints. To

create a relative mission (see “Missions,” page 8) with three waypoints, do

the following.

a. On the UTILITY menu, select WAYPOINT SETUP.

b. On the WAYPOINT SETUP screen, select MISSION SETUP. Use

SELECT to change the mission number to 9.

c. Use SCROLL to move the cursor and then use SELECT to enter the follow-

ing waypoints.

• WP1 = 25 meters bearing 000 degrees

• WP2 = 25 meters bearing 90 degrees

• WP3 = 25 meters bearing 180 degrees

NOTE. CobraWare is designed to help you setup waypoints. For this

quick start guide, practice using only the Cobra-Tac to enter the waypoints.

d. When the waypoints have been entered, select ACCEPT.

e. Stand at your initial position.

f. Activate the training mode (see “Training Mode,” page 13).

g. Start the mission by selecting WAYPOINT NAV on the NAVIGATION

menu. Press SELECT to select mission 9 (created in steps “a” through

“d”). Select ACCEPT, then START to begin the mission.

h. As you move toward waypoint 1, mark an event as MAN MADE (see

“Event Marking Function,” page 26).

i. Practice navigating to each waypoint and marking events. It may be

helpful to walk the course in a parking lot.

NOTE. You must navigate to within a one-meter radius of a waypoint,

otherwise the Diver Navigation Indicator distance will start counting UP,

indicating that you are moving away from the waypoint.

j. When you have navigated to each waypoint, select HOME to travel a re-

ciprocal course back to your initial position (see “Home Function,” page

26).

k. Select

CANCEL to stop the mission (which stops recording). Select

CANCEL again to return to the NAVIGATION menu. Select CANCEL

once more to return to the main menu.

l. Turn the power off to the Cobra-Tac.

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RD Instruments Cobra-Tac User manual

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