Tritech iGC User manual

Intelligent Gyro Compass (iGC)
0707-SOM-00004-7 1 © Tritech International Ltd.
Intelligent Gyro Compass (iGC)
Product Manual
0707-SOM-00004-7

Intelligent Gyro Compass (iGC)
0707-SOM-00004-7 2 © Tritech International Ltd.
© Tritech International Ltd
The copyright in this document is the property of Tritech International Ltd. The document is supplied by Tritech International Ltd on
the understanding that it may not be copied, used, or disclosed to others except as authorised in writing by Tritech International Ltd.
Tritech International Ltd reserves the right to change, modify and update designs and specifications as part of their ongoing
product development programme.
All product names are trademarks of their respective companies.

Intelligent Gyro Compass (iGC)
0707-SOM-00004-7 3 © Tritech International Ltd.
Table of Contents
Help & Support ........................................................................................................... 5
Warning Symbols ........................................................................................................ 6
1. Safety Notices ........................................................................................................ 7
1.1. General ....................................................................................................... 7
1.2. Pressure ...................................................................................................... 7
1.3. Electrics ....................................................................................................... 8
2. Introduction ............................................................................................................. 9
2.1. Intelligent Gyro Compass (iGC) .................................................................... 9
2.2. Intelligent Fibre-optic Gyro (iFG) ................................................................. 10
2.3. Intelligent Interface PCB (iIF) ...................................................................... 10
3. Typical Applications ............................................................................................... 11
4. Installation ............................................................................................................ 14
4.1. Safety Note ................................................................................................ 14
4.2. iGC Mechanical Installation ......................................................................... 14
4.2.1. Introduction ..................................................................................... 14
4.2.2. Magnetic Disturbance ...................................................................... 14
4.2.3. Alignment ........................................................................................ 14
4.2.4. Stiffness .......................................................................................... 15
4.2.5. Collision Protection .......................................................................... 15
4.3. Installation Drawing .................................................................................... 15
4.4. iGC Electrical Installation ............................................................................ 15
4.4.1. Preparation ...................................................................................... 15
4.4.2. Adjusting iGC Mode or Jumpers ....................................................... 17
4.5. Electrical Installation ................................................................................... 18
5. Commissioning ...................................................................................................... 20
5.1. General ...................................................................................................... 20
5.2. Overview .................................................................................................... 20
5.3. Powering up for the first time ...................................................................... 20
5.4. Checking iGC output using a terminal programme ........................................ 21
5.5. Checking iGC output on an RS485 interface ................................................ 22
5.6. iGC data Check procedures ........................................................................ 22
5.6.1. Heading Checks .............................................................................. 23
5.6.2. Pitch & Roll Checks ......................................................................... 23
5.6.3. Heave Acceleration Data Checks ..................................................... 23
5.6.4. Water Ingress Alarm Checks ............................................................ 23
5.6.5. Other Data Checks .......................................................................... 24
6. Calibration ............................................................................................................ 25
6.1. Introduction ................................................................................................ 25
6.2. Physical Offsets ......................................................................................... 25
6.3. Magnetic Offsets ........................................................................................ 25
7. Operation .............................................................................................................. 27
7.1. Introduction ................................................................................................ 27
7.2. Data Output Formats .................................................................................. 27
7.2.1. Proprietary Outputs .......................................................................... 27
7.2.2. Industry Standard Outputs ............................................................... 27
7.2.3. Special Modes ................................................................................. 27
7.3. Operational Issues ..................................................................................... 28
7.4. Using iGC Navigation Software ................................................................... 28
8. Maintenance ......................................................................................................... 31
8.1. Safety ........................................................................................................ 31
8.2. General ...................................................................................................... 31
8.3. Seals ......................................................................................................... 31
8.4. Basic Maintenance Procedure ..................................................................... 31
8.4.1. Pre and Post Dive Checks ............................................................... 31
8.4.2. Storage ........................................................................................... 32

Intelligent Gyro Compass (iGC)
0707-SOM-00004-7 4 © Tritech International Ltd.
8.5. Procedure For Repair of Anodised Surfaces ................................................ 32
8.6. Flooding ..................................................................................................... 32
8.7. Dismantling and Re-assembly ..................................................................... 33
8.7.1. Removal of Pressure Dome ............................................................. 33
8.7.2. Removal Of Sensor Assembly, Interface PCB and Processor
Module ..................................................................................................... 33
8.7.3. Removal Of the Underwater Connector ............................................. 34
8.7.4. Replacement Of the Underwater Connector ...................................... 34
8.7.5. Replacement Of Sensor Assembly, I/F PCB and Processor Module .... 34
9. Basic Fault Finding ............................................................................................... 36
9.1. General ...................................................................................................... 36
9.2. Fault Symptoms ......................................................................................... 36
9.3. Firmware Reprogramming ........................................................................... 37
A. iGC Technical Specifications ................................................................................. 38
B. General Assembly Drawing ................................................................................... 39
C. iGC Bill of Materials .............................................................................................. 40
D. iGC Mode Listing - Proprietary iGC Outputs ........................................................... 41
E. iGC Mode Listing - Special Modes ........................................................................ 43
F. iGC Mode Listing - Industry Standard Modes ......................................................... 46
G. iGC & iFG Electrical Interconnection Schematic ..................................................... 51
H. iGC Recommended Spares .................................................................................. 52

Intelligent Gyro Compass (iGC)
0707-SOM-00004-7 5 © Tritech International Ltd.
Help & Support
First please read this manual thoroughly (particularly the Troubleshooting section, if present).
If a warranty is applicable, further details can be found in the Warranty Statement, 0080-
STF-00139, available upon request.
Tritech International Ltd can be contacted as follows:
Mail Tritech International Ltd
Peregrine Road
Westhill Business Park
Westhill, Aberdeenshire
AB32 6JL, UK
Telephone ++44(0)1224 744 111
Fax ++44(0)1224 741 771
Email [email protected]
Website www.tritech.co.uk
Prior to contacting Tritech International Ltd please ensure that the following is available:
1. The Serial Numbers of the product and any Tritech International Ltd equipment connected
directly or indirectly to it
2. Software or firmware revision numbers
3. A clear fault description
4. Details of any remedial action implemented
Contamination
If the product has been used in a contaminated or hazardous environment you
must de-contaminate the product and report any hazards prior to returning the
unit for repair. Under no circumstances should a product be returned that is
contaminated with radioactive material.
The name of the organisation which purchased the system is held on record at Tritech
International Ltd and details of new software or hardware packages will be announced at
regular intervals. This manual may not detail every aspect of operation and for the latest
revision of the manual please refer to www.tritech.co.uk
Tritech International Ltd can only undertake to provide software support of systems loaded
with the software in accordance with the instructions given in this manual. It is the customer's
responsibility to ensure the compatibility of any other package they choose to use.

Intelligent Gyro Compass (iGC)
0707-SOM-00004-7 6 © Tritech International Ltd.
Warning Symbols
Throughout this manual the following symbols may be used where applicable to denote any
particular hazards or areas which should be given special attention:
Note
This symbol highlights anything which would be of particular interest to the reader
or provides extra information outside of the current topic.
Important
When this is shown there is potential to cause harm to the device due to
static discharge. The components should not be handled without appropriate
protection to prevent such a discharge occurring.
Caution
This highlights areas where extra care is needed to ensure that certain delicate
components are not damaged.
Warning
DANGER OF INJURY TO SELF OR OTHERS
Where this symbol is present there is a serious risk of injury or loss of life. Care
should be taken to follow the instructions correctly and also conduct a separate
Risk Assessment prior to commencing work.

Intelligent Gyro Compass (iGC)
0707-SOM-00004-7 7 © Tritech International Ltd.
1. Safety Notices
1.1. General
Warning
The iGC may contain fluid or gas under pressure and electrical systems at
potentially hazardous voltages.
All installation, operation, maintenance and repair works must be carried out by
competent personnel.
The installation of the iGC and associated components is fully the responsibility
of the user.
The iGC shall be installed, commissioned, operated and maintained in
accordance with this instruction manual, including staying within the maximum
operating conditions given in Appendix A, iGC Technical SpecificationsAppendix
A - iGC Supply Specification. Failure to do so may lead to safety hazards or
equipment failure.
Before starting installation, commissioning, operation or maintenance of the iGC,
personnel should read and understand all relevant sections of this manual.
Any queries, comments or suggestions regarding the content of this manual or
the safe installation, operation or maintenance of the iGC should be referred to
Tritech.
1.2. Pressure
Caution
If a seal has failed AND then acts as a one-way check during flooding, it is
possible that pressurised fluid and gas has been trapped inside the iGC pressure
vessel. This may be indicated by one or more of the following:
1. The iGC has ceased to function after flooding
2. A water-ingress alarm has been generated
3. If the iGC is shaken fluid can be heard or felt moving around inside the housing
4. During removal, the pressure dome is very tight on its threads
5. During removal of the pressure dome there is fluid leakage at the joint
The pressure housing has been designed so that the main seal will cease
to function whilst there is still sufficient thread engagement to prevent the
components from flying apart. The correct procedure for disassembly is given
in Chapter 8, Maintenance.

Safety Notices Intelligent Gyro Compass (iGC)
0707-SOM-00004-7 8 © Tritech International Ltd.
1.3. Electrics
Caution
Any electrical supply or connection should be regarded as dangerous until
proven otherwise by disconnection and isolation or by measurement. This
applies as much to supply circuitry as to the equipment described in this manual.
Before doing any work inside the iGC the electrical power supply to the iGC
should isolated and the power connector unplugged. This includes electrical
faultfinding so as to avoid inadvertent contact between the pressure housing
and exposed connections on any of the electrical components or circuit boards
during removal or installation of the dome.

Intelligent Gyro Compass (iGC)
0707-SOM-00004-7 9 © Tritech International Ltd.
2. Introduction
2.1. Intelligent Gyro Compass (iGC)
The Tritech intelligent gyrocompass is the core component within an integrated and flexible
family of products that provide the user with heading direction, attitude and motion data. This
device finds numerous applications as a component in underwater navigation and positioning
systems, ranging from ROV heading sensors, tooling skid positioning, heave compensation
systems, construction projects, vessel navigation etc.
As standard the iGC is supplied in a 1-atmosphere pressure housing suitable for use down
to 4000 metres depth, but is available in a 6000 metre version or in a ‘surface’ housing (i.e.
suitable for use inside an existing pressure vessel or at the surface) as an option.
The iGC is based around a sophisticated set of sensors measuring acceleration, magnetic
field and rate of turn on three orthogonal axes. Data from these sensors is processed
internally using state of the art digital signal processing and advanced adaptive filtering
techniques to give outputs of heading, pitch, roll and heave acceleration. Optionally, the unit
can also provide surge and sway accelerations.
In order to find applications in a wide range of areas, the output data from the iGC is selectable
by the user to match numerous industry standard formats. This allows the iGC to ‘emulate’
more expensive or existing heading sensors and therefore provide an easy upgrade or
replacement path for customers looking for a more reliable or compact solution.
As standard, the iGC is supplied with a PC software application that gives a clear animated
display of heading, pitch, roll, turns counter, heave acceleration and iGC status. This PC
programme is normally used when the user does not have an effective heading display, for
diagnostics / additional data control or in applications where an additional display is useful
to complement the existing heading display system.
The iGC communicates with the ‘host’ system via a digital communication link, either using
RS232 or RS485. The data rate and output telegram format are user selectable depending
on the application.
Power to the iGC is nominally 24V dc at 250mA, but supply voltages in the range 12V to
26V are acceptable.
Since the iGC is based around magnetic North detecting sensors, it is sensitive to external
magnetic fields that are not produced by the earth’s magnetic field. Such fields may vary in
intensity and direction, and will affect the performance and accuracy of the iGC outputs to a
greater or lesser extent, depending on their severity.
By careful positioning of the iGC on the host system, local ‘soft iron’ magnetic errors can
normally be avoided, but external effects may produce undesirable results under certain
circumstances.
There are several other members of the iGC product family that increase the functionality
and application areas of the iGC.
These are described in more detail later in this manual and comprehensively in their own
Operators Manuals, but comprise:
1. Intelligent Fibre-optic Gyro (iFG)
2. Intelligent Interface PCB (iIF)

Introduction Intelligent Gyro Compass (iGC)
0707-SOM-00004-7 10 © Tritech International Ltd.
2.2. Intelligent Fibre-optic Gyro (iFG)
This is a solid-state single-axis fibre-optic gyro (FOG) sensor system that measures rate of
turn to a high degree of accuracy, and with very low drift-rate. This sensor when coupled
with an iGC provides a magnetic-north referenced fibre-optic stabilised gyro system with
a drift rate of ~1° heading per hour. The combination of an iGC and iFG can be used to
replace traditional spinning mass gyro compasses with a more reliable solid-state solution
with significantly better drift-rate performance. The effects of extraneous magnetic fields is
also much reduced with the iGC / iFG combination.
2.3. Intelligent Interface PCB (iIF)
For systems where an RS232 or RS485 sensor output is not compatible with the existing
heading sensor interface, Tritech have developed a number of interface PCBs that can be
used to convert the digital telemetry signals from the iGC and iFG into a compatible format.
These PCBs are installed in the host system in place of the existing heading sensor interface
PCB, and emulate the original sensor outputs (e.g. synchro, analogue, digital etc.) but use
the iGC / iFG as the data source.
These PCBs offer a simple ‘hardware’ upgrade to existing systems, without the requirement
to rewrite control system software or redesign hardware. They also offer additional
capabilities over existing systems, such as the ability to receive data from a North-seeking
gyro and convert to the host format, output of pitch and roll signals in the host system’s correct
format, automatic selection of the ‘best’ heading source and improved autoheading / turns
counter interfaces.
At the time of writing this manual, the following iIF PCBs are available:
1. Ametek Straza / Perry Tritech Scorpio ROV
2. Perry Tritech Super Scorpio ROV
3. Subsea 7 (Subsea Offshore) Pioneer ROV
Tritech are continually expanding the range of supported systems, so please contact Tritech
if you have requirements that are not covered by the list above.
Please refer to the Chapter 3, Typical Applications section for details of the common
configurations that the iGC product family can be used in.

Intelligent Gyro Compass (iGC)
0707-SOM-00004-7 11 © Tritech International Ltd.
3. Typical Applications
There are various method of integrating the iGC with existing control systems, the following
drawings illustrate typical applications.

Typical Applications Intelligent Gyro Compass (iGC)
0707-SOM-00004-7 12 © Tritech International Ltd.

Typical Applications Intelligent Gyro Compass (iGC)
0707-SOM-00004-7 13 © Tritech International Ltd.
In addition to the sketches shown, there are numerous alternative options for interconnection
of the iGC product family to existing or bespoke control systems.
If your desired application is not shown, please contact Tritech for advice on the best method
of achieving the interface that you require.

Intelligent Gyro Compass (iGC)
0707-SOM-00004-7 14 © Tritech International Ltd.
4. Installation
4.1. Safety Note
Before commencing installation of the iGC:
1. Refer to Chapter 1, Safety Notices
2. All relevant parts of this section of the manual should be read and understood
4.2. iGC Mechanical Installation
4.2.1. Introduction
When deciding where to mount the iGC, consideration should be given to:
1. Its location relative to magnetically active materials on the host system
2. Alignment with the axes of the host system
3. Stiffness of the mounting arrangement
4. Collision protection
4.2.2. Magnetic Disturbance
To reduce the effects of fixed magnetic disturbances on the iGC output, it should be mounted
as far as is practically possible from the following:
1. Ferrous or other magnetically active materials (including fasteners or brackets used to
mount the iGC)
2. Sources of electrically induced magnetic fields such as motors and transformers
3. Moving equipment (e.g. manipulator arms, pan & tilt units etc.)
The iGC is more susceptible to ferrous materials underneath the assembly than from the
side or above.
4.2.3. Alignment
The electrical connector is mounted at the “rear” of the iGC. In addition, three meridian lines
have been engraved into the body of the iGC. These show the forward, port and starboard
directions of the iGC axes. (Refer to Section 4.3, “ Installation Drawing ” for details).
To maximise the accuracy of the iGC outputs, its pitch, roll and yaw axes should be aligned,
as accurately as possible, with the pitch, roll and yaw axes of the host system / vehicle.
If necessary, small corrections can be made in accordance with the commissioning and
calibration sections of this manual, provided that the existing host control system can provide
this function, or the iGC is being used with the iGC PC software, iFG or iIF.

Installation Intelligent Gyro Compass (iGC)
0707-SOM-00004-7 15 © Tritech International Ltd.
4.2.4. Stiffness
The iGC should be rigidly mounted so that flexibility and / or system vibration does not affect
the outputs.
4.2.5. Collision Protection
To protect against accidental damage, the iGC should be mounted in a protected location.
The protection around the iGC should not be manufactured form a ferrous material.
4.3. Installation Drawing
The following drawing shows installation dimensions and fastener details for the installation
of the iGC:
NB: As stated previously non-magnetic fasteners and mounting bracket should be used for
mounting the iGC.
4.4. iGC Electrical Installation
4.4.1. Preparation
All electrical connections to the iGC are via a single Subconn 8-pin micro series connector.
This connector is a Male on the iGC (MCBH8MSS) and therefore a female is required on the
interface cable (MCIL8F or equivalent).
The connector should be made up in accordance with Subconn guidelines, as detailed below
(taken from MacArtney Subconn standard literature):

Installation Intelligent Gyro Compass (iGC)
0707-SOM-00004-7 16 © Tritech International Ltd.
1. The connector should not be exposed to long-term heat or sunshine. If this occurs, and
the connectors are very dry, soak in fresh water before use
2. Ensure the connectors are lubricated - the recommended lubricant is Molykote 44 Medium
-but use sparingly. Half a match head dose per contact is adequate.
3. Any accumulation of sand or mud in the female contact should be removed with fresh
water. Failure to do so could result in the splaying of the female contact and damage to
the O-ring seals.
4. Do not overtighten the bulkhead nuts
5. Do not disconnect by pulling on the cable and avoid sharp bends at cable entry
6. When using bulkhead connectors see that there are no angular loads as this destroys the
connector
7. When disconnecting, pull straight, not at an angle. Ensure the above points are fulfilled
to get the best out of your connectors. If in doubt, please contact your local distributor or
MacArtney A/S for advice.
The mated connector should be retained using the Delrin locking sleeve supplied with
the iGC. This ensures that the connector does not become inadvertently partially or fully
disconnected.
The iGC requires electric power at 24v DC nominal supply, operating current typically
between 220mA and 250mA. The iGC will however function correctly at any voltage in the
range 12v DC to 26v DC.
The power supply should be from a regulated and smooth (low ripple) power supply for best
results. An unregulated or un-smoothed supply should not be used.
The following drawing details the pin-outs of the iGC:
If the operating mode that the iGC is to be used in differs from the mode settings as the unit
was supplied, the iGC will need to be opened and the Mode Switch settings adjusted. This
is covered in section 7.4.2 below.
If RS485 telemetry is going to be used, check that the selector jumpers JP1, JP2 and JP3
are in their correct positions as the unit was supplied. If not, the iGC will need to be opened
and the Jumper settings adjusted as described below. The correct settings are given in the
following table:

Installation Intelligent Gyro Compass (iGC)
0707-SOM-00004-7 17 © Tritech International Ltd.
Mode Jumper JP1 Jumper JP2 Jumper JP3
RS232 only (don't care) (don't care) (don't care)
RS485 (end
terminated)
Position 2-3 Position 2-3 IN
RS485
(unterminated)
Position 2-3 Position 2-3 OUT
Note
Depending on the manufacturing date of the iGC, the unit may not have a tri-
jumper assembly. In this instance the presence of the jumpers JP1 and JP2 is
only required when using RS485 communications.
4.4.2. Adjusting iGC Mode or Jumpers
In order to adjust the Mode switch settings the iGC must be opened. Firstly isolate the iGC
supply and disconnect the iGC from its interconnecting cable (if already connected).
Follow the procedure for iGC Disassembly (see Section 8.7, “ Dismantling and Re-assembly
”). This procedure exposes the internal iGC components.
Identify the Mode Selector switch (SW1) on the Interface PCB (Item 4 on the G.A.). Refer
to the photograph below, and to the General Assembly drawing in Appendix B, General
Assembly Drawing.
Set the DIL mode switch (SW1) to the desired setting (as determined above – and according
to the switch settings from Appendices C and D). Operate the switches carefully with a sliding
motion using a small jeweller’s screwdriver or similar, ensuring that the switches are moved
fully into the desired position.

Installation Intelligent Gyro Compass (iGC)
0707-SOM-00004-7 18 © Tritech International Ltd.
Once the DIL switch has been set, the RS485 jumpers should be checked and set
accordingly.
The Jumpers are identified as the shorting links (see photograph). The position to set the
Jumpers can be seen from the photographs below:
Settings for RS485 Mode
Terminated with 120R Unterminated
Note
For newer iGC units, JP1 and JP2 are no longer tri-state jumpers.
4.5. Electrical Installation
The following procedure should be followed to complete the Electrical Installation of the iGC:
1. Make any necessary wiring and modifications to the Host control system to provide the
appropriate power supply and telemetry circuits
2. With the power to the Host control system isolated, attach the interconnecting cable to the
appropriate underwater connector at the Host end
3. Using a digital multimeter, insert probes into sockets 1 and 2 of the interconnecting cable
(prior to connecting to the iGC)
4. Carefully power-up the Host supply (or the iGC supply circuit if switchable). Confirm that
the output voltage is the correct value and polarity
Caution
Do not connect the cable to the iGC until provision of correct voltage to the correct
pins on the iGC connector has been checked (see Section 5 - Commissioning).

Installation Intelligent Gyro Compass (iGC)
0707-SOM-00004-7 19 © Tritech International Ltd.
Note: The iGC input power connection is protected against reverse polarity
supply connections. If power is inadvertently connected in reverse polarity, the
iGC will not power up, but will not be damaged.
Care should be taken when providing power to an iGC and iFG combined system. The iGC
has a lower voltage range than the iFG. Over voltaging the iGC will result in damage.
Caution
1. When the correct iGC supply voltage has been confirmed, isolate the iGC supply and
check that there is no power present on the connector sockets (pins 1 & 2)
2. Connect the female Subconn connector to the iGC
3. Carefully power-up the Host supply (or the iGC circuit if switchable)
4. Check correct operation of the iGC according to Chapter 7, Operation.

Intelligent Gyro Compass (iGC)
0707-SOM-00004-7 20 © Tritech International Ltd.
5. Commissioning
5.1. General
Before starting commissioning of the iGC :
1. Refer to Chapter 1, Safety Notices
2. All relevant parts of this section of the manual should be read and understood
3. All electrical power and data connections must be complete and tested
5.2. Overview
If the Electrical Installation procedures in Section 4.4, “iGC Electrical Installation” have been
followed correctly, the iGC should function correctly when it is powered-up for the first time.
On application of DC power, the iGC reads the Mode selector switch and calculates the
required internal settings to match the required output format. Prior to entering the operational
mode, the iGC transmits a configuration data packet from the RS232 port. This packet is sent
at a data rate of 19,200 baud, N,8,1 and comprises a number of ASCII text messages about
the iGC mode switch settings and its interpretation of these.
After 5 seconds, the iGC enters the actual output mode selected and begins to function
according to the rules of the mode settings.
The reason for transmitting the configuration packet is that it allows users to check the correct
operating mode and settings using a simple terminal programme (e.g. HyperTerminal) for
faultfinding. Under most circumstances, the Host data interface should ignore or discard this
data and begin responding to or processing the normal output telegram packets once they
start.
5.3. Powering up for the first time
With the host control system powered up and ready, apply power to the iGC. Check that
the correct data appears 5 seconds or so after application of power. If the data is detected
and appears to be correct, the iGC data check procedures in Section 8.7 below should be
followed.
If no data appears, check that the iGC connections and interfaces are all correct. A very
common commissioning problem that can occur with RS232 and RS485 interfaces is that
the TX and RX lines (for RS232), A+ and B- lines (for RS485) are accidentally swapped the
wrong-way around.
With these lines swapped, no damage should occur but the system will not function – it is
therefore safe to try swapping the telemetry connections.
If problems persist, it may be necessary to examine the data signals with an oscilloscope or
a breakout box with LED indicators.
If the iGC data is still not received correctly, the output and mode settings of the iGC should
be checked with a terminal programme