®
USER MANUALFOR MODELS

VIPER 4
VIPER 8
VIPER 16
URM18PH392
May 2020 Rev. A

Rev. AMay 2020

USER MANUAL
Copyright © 2020 by Alken, Inc. dba Polhemus
Colchester, Vermont, U.S.A.
All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in
any form or by any means, mechanical, photocopying, recording or otherwise, without the prior written
permission of Polhemus. No patent liability is assumed with respect to the use of the information contained
herein. While every precaution has been taken in the preparation of this manual, Polhemus assumes noresponsibility for errors or omissions. Neither is any liability assumed for damages resulting from use of theinformation contained herein.
Windows® is a registered trademark of Microsoft Corporation.
Linux® is the registered trademark of Linus Torvalds in the U.S. and other countries.

Medical Device Use
The VIPER™ products are certified to meet the EN60601 conformance standards as noted in the following
sections. If VIPER™ products are used in a medical setting it is intended that they are used as medical device
components. Medical device components are products integrated into other medical devices or medical device
systems.
The VIPER™ system does not have a specific indication for use and there are no stand-alone regulatory clearances
or approvals for the VIPER™ itself.
As defined by FDA (21 CFR 820.3(c)), a component is any raw material, substance, piece, part, software, firmware,labeling, or assembly that is intended to be included as part of the finished, packaged, and labeled device.
The end user/OEM/VAR/Distributor must determine how the VIPER™ products will be used and comply with all
FDA/CE regulations pertaining to the development and sale of finished medical devices and all other regulatory
requirements.

Rev. A2

May 2020

USER MANUALFCC Statement
This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to part
15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference in a
residential installation. This equipment generates, uses, and can radiate radio frequency energy and, if not
installed and used in accordance with the instructions, may cause harmful interference to radio communications.
However, there is no guarantee that interference will not occur in a particular installation. If this equipment does
cause harmful interference to radio or television reception, which can be determined by turning the equipment
off and on, the user is encouraged to try to correct the interference by one or more of the following measures:- Reorient or relocate the receiving antenna.
- Increase the separation between the equipment and receiver.
- Connect the equipment into an outlet on a circuit different from that to which the receiver is connected.
- Consult the dealer or an experienced radio/TV technician for help.
EMC/EMI:IEC 60601-1-2 Medical Electrical Equipment, Edition 4.0

Immunity Requirements:
EN61000-4-2:2009
EN61000-4-3:2005/A1:2008/A2:2010
EN61000-4-4:2004/A1:2010
EN61004-5:2006
EN61000-4-6:2009
EN61000-4-8:2010
EN61000-4-11: 2004

Electrostatic Discharge
Radiated Immunity
EFT/Burst Power Leads
Surge Immunity
Conducted Immunity, Power Leads
Power Frequency Magnetic Fields
Voltage Dips and Interrupts

Note: The conducted emission herein only applies if a Polhemus-supplied power supply is used with the VIPER™
unit.

Electrical Safety Approvals
IEC 60601-1 Medical Electrical Equipment, Edition 3.1
Classifications
Electric Shock Protection

Class I - protectively earthed with power from supply mains

Shock Protection Degree

Sensors and TX-1 Source = BF / TX2 and TX4 Sources = B

Ingress Protection

Sensors and TX-1 Source = IP67 TX2 and TX4 Sources = IPX0 (see Section 7)

Sterilization

Sensors and TX1 = ethylene oxide gas

Flammability

Not intended for use in a flammable or oxygen rich atmosphere

Mode of Operation

Continuous

Rev. A3

May 2020

USER MANUALHOW TO USE THIS MANUAL™

This user manual serves as a reference guide for the setup and operation of the Polhemus VIPER tracker.
To quickly set up and run a new VIPER™ system, refer to Section 3. GETTING STARTED. This section offers a stepby-step approach to guide you in installing, configuring and running your device in a simplified scenario of one
Source and one Sensor.
The manual is divided into several parts:
Section 1. VIPER™ SYSTEM OVERVIEW provides detailed descriptions and physical information about the
hardware and software components and accessories that make up the VIPER™ system.
Section 2. OPERATION provides general description of how the tracker can be deployed and some advice on
physical installation.
Section 3. GETTING STARTED is a detailed step-by-step guide to installation, setup and simple operation of aminimal system. This section is designed to familiarize you with the basic process of setting up a system without
delving into details of larger or more complex installations.
Section 4. VIPER™ COMMAND INTERFACE lists the different commands for controlling VIPER™ and describes
their functions.
Section 5. PRECAUTIONS Outlines precautions to observe when using VIPER™.
Section 6. BIT ERRORS provides a list of the system errors and their meanings.
Section 7. EXPLANATION OF SYMBOLS provides an explanation of symbols used in this manual.
Appendix A. Terms & Acronyms is a good resource for terms used commonly throughout the manual. Follow
red definition hyperlinks placed in each section to read the term definition in Appendix A. If reading with a PDF
reader: After following a definition link, hold down the Alt key plus the left arrow on your keyboard to return toyour place in the manual.

Throughout the manual, look for the following symbols for background information, helpful tips and cautionary
notes:
More Information.

Helpful tip.

Caution, Warning, or Safety Note.

Rev. A4

May 2020

USER MANUALSAFETY NOTICESrdThis apparatus has been designed and tested in accordance with EN60601-1, 3 edition.
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Before powering up the instrument, be aware that the main plug shall only be inserted in a socket outlet
provided with a protective ground contact. You must not negate the protective action by using an extension
cord (power cable) without a protective conductor (grounding). Grounding one conductor of a twoconductor outlet is not sufficient protection.
The VIPER™ sensors and sensor ports use standard USB-C style connectors. These ports are NOT a USB
connection. Only plug a VIPER™ sensor/stylus into these sensor ports.
When connecting a host device to the VIPER™ USB or RS-422 output port, ensure that the host device iscompliant to the relevant safety standard for that device (EN60950/EN61010).
Only connect a Polhemus magnetic source into the source ports.
Do not operate the instrument in the presence of flammable gases or fumes. Operation of any electricalinstrument in such an environment constitutes a definite safety hazard.
Only use the sync port with a Polhemus provided sync cable and in accordance with the instructions in thismanual.
Do not connect two magnetic sources of the same frequency. The SEU will cease operation.
Be sure to read and understand the concept of Hemisphere of Operation in this manual and operate theproduct using the correct Hemisphere of Operation setting.
Be sure to read and understand the setup and operation of this product to ensure accurate measurements.
Read the Precautions section of this manual.

WARNINGS

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This instrument contains no user serviceable parts. Do not attempt to service the unit. Return it to Polhemus
for repair.
Do not perform any unauthorized modification to the instrument.
Do not use the instrument in a manner not specified by the manufacturer.
Only use the DC power supply provided by Polhemus: part number 1C0614.
Ensure the VIPER™ power supply or power cord to the power supply is accessible so mains power can beremoved quickly.

CONTRAINDICATIONSThere are no contraindications with the VIPER™ system as provided by Polhemus. The final medical product that
the VIPER™ system is incorporated into needs to be evaluated for contraindications.

Rev. A5

May 2020

USER MANUAL
CLEANING
The only required maintenance is cleaning the System Electronics Unit (SEU), Sources, Sensors and Cables. If the
instrument requires cleaning:
1.
2.

Remove power from the SEU.
Clean the external surfaces of the SEU, Cables and external shells of the Sources and Sensors with a soft
cloth dampened with a mixture of mild detergent and water.

Make sure that the SEU is completely dry before reconnecting it to a power source.

STERILIZATION
No component of VIPER™ is provided sterilized. Only the sensors and TX1 Source can be sterilized and only withETO Gas. There is no known limit on the number of cycles.

STORAGE AND TRANSPORT
Temperature
Relative Humidity
Atmospheric Pressure-10C to +50C
10% to 90% non-condensing
50kPa to 106kPa

DISPOSAL
VIPER™ components are considered electronic waste and should be disposed of in accordance with local
ordinances.

Rev. A6

May 2020

USER MANUALSPECIFICATION
Update Rate (per Sensor, simultaneous samples)

VIPER™ 4 - 240Hz, VIPER™ 8 and VIPER™ up to 960Hz. (30, 60, 120, 240, 480 or 960Hz).
Latency

960Hz – 1 millisecond. 480Hz – 2 milliseconds. 240Hz – 3.5 milliseconds.
Number of Sensor Inputs

VIPER™ 4: 1 to 4; VIPER™ 8: 1 to 8; VIPER™ 16: 1 to 16.
Number of Source Inputs

VIPER™ 4: 1; VIPER™ 8: 2; VIPER™ 16: 4.
I/O Ports

USB 2.0; RS422 tested to 921,600. (Possible to program baud rate to 7,372,800).
Static Accuracy

0.015 in. RMS for X, Y or Z position; 0.10° RMS for Sensor orientation (magnetically clean
environment, FTT® turned off).
Resolution

0.00004 in. (0.0010 mm) at 12 in. (30 cm) range; 0.0003° orientation.
Range

30 in. (76 cm) radius from Source at above specifications with TX2. Useful operation in excess of
72 in. (182 cm) in radius with one Source. Using multiple Sources extends tracking range further.
Multiple Systems

Provisions available to operate multiple systems in same environment.
Angular Coverage

All-attitude.
Data Format

IEEE 754 binary.
External Sync

Configurable port for either input or output. (See Section 2.3.)
Physical Characteristics

See Appendix C.
Power Requirements

5 Volt 8 amps max; 100-240VAC and 50-60Hz.
Operating Temperature

10°C-40°C at a relative humidity of 10% to 90% non-condensing.
Operating Environment

SEU/TX2/TX4: Rated IPX0. Not protected against the ingress of water or dust. Operate, store
and transport in a dry environment.
TX1/Sensors: Rated IP67. May be submerged in freshwater up to 1 meter for up to 30 minutes.
Dust-tight.
Atmospheric Pressure 50kPa to 106kPa.

Rev. A7

May 2020

USER MANUAL

Rev. A8

May 2020

USER MANUALTABLE OF CONTENTS
How To Use This Manual ....................................................................................................................................... 4
Specification .......................................................................................................................................................... 7
Table of Contents................................................................................................................................................... 9
List of Figures ....................................................................................................................................................... 11
1.
VIPER™ SYSTEM OVERVIEW ................................................................................................................... 13
1.1
INTRODUCTION ....................................................................................................................................13
1.1.1
1.2

VIPER™ SYSTEM COMPONENTS..............................................................................................................14

1.2.1
1.2.1.1

1.2.2
1.2.3
1.2.4
2.

HOW VIPER™ MOTION TRACKING WORKS ............................................................................................13
VIPER™ SEU..................................................................................................................................14
LED PATTERNS

15SENSOR ..........................................................................................................................................16
STYLUS ...........................................................................................................................................17
SOURCE ..........................................................................................................................................17

2.1
2.2
2.3
2.4

OPERATION ............................................................................................................................................ 19
FTT® MODE ........................................................................................................................................19
I/O CONSIDERATIONS ...........................................................................................................................20
EXTERNAL SYNC ...................................................................................................................................21
SOFT RESET ........................................................................................................................................21

3.1

GETTING STARTED .................................................................................................................................. 23
SETTING UP VIPER™ HARDWARE FOR THE FIRST TIME .................................................................................23

3.

3.1.1
3.1.2
3.2
3.3

MAKE CONNECTIONS.........................................................................................................................23
PLACE SOURCE AND SENSOR(S)............................................................................................................23
INSTALL HOST SOFTWARE (WINDOWS®) ...................................................................................................24
RUN VIPER™ COMMAND MANAGER .......................................................................................................25

3.3.1
3.4

UPDATE VIPER™ COMMAND MANAGER...............................................................................................25
VIPER™ COMMAND MANAGER USER INTERFACE OVERVIEW .........................................................................26

3.4.1
3.4.2
3.4.2.1
3.4.2.2
3.4.2.3

3.4.3
3.5

DISPLAYING VIPER™ P&O DATA .........................................................................................................27
CONFIGURING VIPER™ .....................................................................................................................28
COMMONLY USED SETTINGSADVANCED SETTINGSPERSISTENCE

28
29
30

KEYBOARD SHORTCUTS ......................................................................................................................30
CONFIGURING VIPER™ MULTI-SOURCE MODES OF OPERATION.....................................................................31

3.5.1
3.5.2
3.5.3
3.5.3.1

3.5.4
3.5.5

SINGLE-SOURCE MODE ......................................................................................................................31
DUAL-SOURCE MODE ........................................................................................................................31
LOCAL-SOURCE MODE .......................................................................................................................31
NEAREST SOURCE32

CUSTOM MULTI-SOURCE MODE CONFIGURATION ....................................................................................33
EXPANDED TRACKING AREA MULTI-SOURCE MODE...................................................................................33

3.6

USING A STYLUS WITH VIPER™ ..............................................................................................................34

4.1
4.2

VIPER™ COMMAND INTERFACE ............................................................................................................. 35
COMMAND SUMMARY ..........................................................................................................................35
CONFIGURATION COMMANDS, PERSISTENT ...............................................................................................37

4.

4.2.1

FRAME RATE COMMAND ................................................................................................................37

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USER MANUAL
4.2.2
4.2.3
4.2.4
4.2.5
4.2.6
4.2.7
4.2.8
4.2.9
4.2.104.2.114.2.124.2.134.2.144.2.14.1
4.2.14.2

4.3
4.3.1
4.3.2
4.3.3
4.3.4
4.4
4.4.1
4.4.2
4.4.3
4.4.4
4.5

4.5.1
4.5.2
4.5.3
4.5.4
4.5.5
4.5.6
4.6
4.6.1
4.6.2
4.6.3

UNITS COMMAND ...........................................................................................................................37
SYNC MODE COMMAND .................................................................................................................38
STYLUS MODE COMMAND ..............................................................................................................38
SEU ID COMMAND...........................................................................................................................39
SOURCE ROTATION COMMAND ......................................................................................................39
SOURCE CONFIGURATION COMMAND ...........................................................................................40
PREDICTION FILTER COMMAND ......................................................................................................42HEMISPHERE COMMAND ................................................................................................................42
FILTER COMMAND...........................................................................................................................43
INCREMENT COMMAND .................................................................................................................46
FTT MODE COMMAND ....................................................................................................................46
VIRTUAL SENSOR COMMAND..........................................................................................................47
SOURCE CONFIGURATIONS AND MODES OF OPERATION ...........................................................49
SOURCE SELECT COMMANDSENSOR ORIGIN COMMAND

49
50

CONFIGURATION COMMANDS, NOT-PERSISTENT ........................................................................................52
RS-422 SERIAL PORT CONFIGURATION COMMAND ........................................................................52
DUAL OUTPUT MODE COMMAND...................................................................................................53
TIP OFFSET COMMAND ...................................................................................................................53
BORESIGHT COMMAND ..................................................................................................................54
P&O COMMANDS ................................................................................................................................55
STANDARD P&O FRAME ....................................................................................................................55
ALTERNATIVE P&O FRAME WITH ACCELERATION ....................................................................................56
SINGLE PNO COMMAND..................................................................................................................57
CONTINUOUS PNO COMMAND .......................................................................................................57
READ-ONLY COMMANDS ....................................................................................................................59

BIT RESULTS COMMAND .................................................................................................................59
STATION MAP COMMAND ..............................................................................................................59
DISTORTION MAP STATUS COMMAND ...........................................................................................59
WHO AM I COMMAND ....................................................................................................................60
SENSOR WHO AM I COMMAND.......................................................................................................60
SOURCE WHO AM I COMMAND ......................................................................................................61
EXECUTIVE COMMANDS .....................................................................................................................62PERSIST COMMAND ........................................................................................................................62
BLOCK CONFIG RESET COMMAND...................................................................................................62
ENABLE DISTORTION MAP COMMAND ...........................................................................................63

5.
PRECAUTIONS ........................................................................................................................................ 64
6.
BIT ERRORS ............................................................................................................................................ 65
7.
EXPLANATION OF SYMBOLS ................................................................................................................... 66
APPENDIX A.
TERMS & ACRONYMS ......................................................................................................................67
APPENDIX B.
SOURCE HEMISPHERES ...................................................................................................................75
APPENDIX C.
SENSOR AND SOURCE DIMENSIONS ...............................................................................................77
APPENDIX D.
LIMITED WARRANTY AND LIMITATION OF LIABILITY ......................................................................85
APPENDIX E.
CUSTOMER SERVICE ........................................................................................................................86

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USER MANUAL
LIST OF FIGURESFIGURE 1. VIPER™ SEU FRONT VIEW: VIPER™ 4, VIPER™ 8, VIPER™ 16 ...................................................................14
FIGURE 2. VIPER™ SEU REAR VIEW: VIPER™ 4/8, VIPER™ 16 ...................................................................................14
FIGURE 3. VIPER™ 8 SEU PANEL LEGEND ..................................................................................................................14
FIGURE 4. VIPER™ SEU DIMENSIONS (APPROXIMATE), INCHES (CM) ......................................................................15
FIGURE 5. VIPER™ SENSORS. FROM TOP: FT-STANDARD, FT-FLATSIDED, AND FT-CLIP (WITH CLIP SHOWN) .........16
FIGURE 6. VIPER™ FT3-STYLUS AND FT8-STYLUS ......................................................................................................17
FIGURE 7. VIPER™ TX2 SOURCE ................................................................................................................................18
FIGURE 8. PINOUT VIPER™ RS-422 MALE CONNECTOR ............................................................................................20
FIGURE 9. VIPER™ EXTERNAL SYNC PINOUT .............................................................................................................21
FIGURE 10. GETTING STARTED: CONNECTIONS ........................................................................................................23
FIGURE 11. SENSOR PLACED IN +X HEMISPHERE......................................................................................................24
FIGURE 12. SEU AND SENSOR BLOCK CONFIGURATION PANELS..............................................................................29
FIGURE 13. VIPER™ 16 SINGLE-SOURCE MODE ........................................................................................................31
FIGURE 14. VIPER™ 16 DUAL-SOURCE MODE ...........................................................................................................31
FIGURE 15. VIPER™ 8 LOCAL SOURCE LOCATIONS ...................................................................................................31
FIGURE 16. VIPER™ 16 LOCAL SOURCE LOCATIONS .................................................................................................32
FIGURE 17. VIPER™ 16 NEAREST SOURCE, EXAMPLE A ............................................................................................32
FIGURE 18. VIPER™ 16 NEAREST SOURCE, EXAMPLE B ............................................................................................32
FIGURE 19. VIPER™ 16 NEAREST SOURCE, EXAMPLE C ............................................................................................32
FIGURE 20. LOCAL SENSOR GROUPS.........................................................................................................................47
FIGURE 21. VIRTUAL SENSOR EXAMPLE ...................................................................................................................48
FIGURE 22. SOURCE HEMISPHERES ..........................................................................................................................75
FIGURE 23. OUTLINE DIMENSIONS (APPROX.), VIPER™ FT-STANDARD SENSOR ......................................................77
FIGURE 24. OUTLINE DIMENSIONS (APPROX.), VIPER™ FT-FLATSIDED SENSOR ......................................................78
FIGURE 25. OUTLINE DIMENSIONS (APPROX.), VIPER™ FT-CLIP SENSOR .................................................................79

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USER MANUALFIGURE 26. OUTLINE DIMENSIONS (APPROX.), VIPER™ FT SENSOR CLIP .................................................................80
FIGURE 27. OUTLINE DIMENSIONS (APPROX.), TX2 STANDARD SOURCE .................................................................81
FIGURE 28. OUTLINE DIMENSIONS (APPROX.), TX4 SOURCE ...................................................................................82
FIGURE 29. OUTLINE DIMENSIONS (APPROX.), VIPER™ HR SOURCE ........................................................................83

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USER MANUAL
1. VIPER™ SYSTEM OVERVIEW
Congratulations on your purchase of VIPER™, the latest generation of Polhemus Tracking Systems. The VIPER™
design has several new innovations. These innovations include FTT® (Fly True Technology) – a new technologythat adds real-time eddy current distortion mitigation, up to four magnetic sources in a single System Electronics
Unit (SEU), and faster update rates as high as 960Hz.
VIPER™ is available in three different models: VIPER™ 4, VIPER™ 8, and VIPER™ 16.

1.1 INTRODUCTION
The Polhemus VIPER™ is an electromagnetic tracking system based on a scalable architecture that supports up to
16 Sensors and 4 Sources in a single chassis.
The flexible VIPER™ design offers unprecedented versatility and scalability for the Polhemus motion tracking
user.

1.1.1 HOW VIPER™ MOTION TRACKING WORKS
An electromagnetic (EM) field is emitted from one or more Sources. Sensors detect the emitted field(s) and the
System Electronics Unit (SEU) calculates Position and Orientation (P&O) of each of the Sensors. The P&O data isstreamed from the SEU via USB or RS-422 to a connected host computer.
On a Windows® host PC the VIPER™ Command Manager app (VPcmdMgr) may be used to visualize the motion of
the Sensors. Open-source programming libraries and sample programs are available for developing custom
applications that use the Sensor P&O data on Windows® or other computer operating system platforms.
The VIPER™ system operation is configured and controlled by an open source command interface. VIPER™
commands are applied to the system via the VPcmdMgr or via custom end-user software. The VIPER™ command
set is explained in detail in Section 4. of this user manual. VPcmdMgr users and software developers will findexplanations of the available commands in online help and useful tips and information displayed on the
VPcmdMgr display.
VIPER™ system hardware components are precisely calibrated at the factory using NIST (National Institute ofStandards and Technology) traceable fixturing. Recalibration of the system is never required.

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USER MANUAL
1.2 VIPER™ SYSTEM COMPONENTS
The VIPER™ System consists of a System Electronic Unit (SEU), one to sixteen Sensors and one to fourelectromagnetic (EM) Sources. Communication with the system is via USB 2.0 or RS-422. The system only
requires 5 volt power. Host computer apps, programming libraries, and documentation are installed via web
download or thumb drive.

1.2.1 VIPER™ SEU
The VIPER™ SEU comes in three variations: The VIPER™ 4 system supports one EM Source and up to four Sensors.
 The VIPER™ 8 system supports up to two EM Sources and up to eight Sensors.
 The VIPER™ 16 system supports up to four EM Sources and up to sixteen Sensors.

FIGURE 1. VIPER™ SEU FRONT VIEW: VIPER™ 4, VIPER™ 8, VIPER™ 16

FIGURE 2. VIPER™ SEU REAR VIEW: VIPER™ 4/8, VIPER™ 16

Figure 3 below identifies controls and ports on a VIPER™ 8 chassis.

FIGURE 3. VIPER™ 8 SEU PANEL LEGEND

Figure 4 below details approximate VIPER™ SEU dimensions. Note that all SEUs have the same footprint. Rubber
feet add approximately 0.2 inches (0.51 cm) to the height.

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URM18PH392 Rev A. May 2020

USER MANUALFIGURE 4. VIPER™ SEU DIMENSIONS (APPROXIMATE), INCHES (CM)1.2.1.1 LED P ATTERNSStartup sequence:
1.

All SEU LEDs turn red for approximately 2 seconds, and then flash green once.

2.

Each sensor board will flash a blue LED pattern corresponding to detected Source frequency:a.

Sensor Ports 1, 2, 3, or 4 will flash blue:
 ONCE for corresponding Source frequency 1-4.
For example, Source Frequency 1 will cause sensor port 1 LED to flash blue ONCE during
startup sequence, Source Frequency 2 will cause port 2 to flash blue ONCE, etc.
 TWICE for Source frequencies 5-8, and so on.
For example, Source Frequency 5 will cause sensor port 1 LED to flash blue TWICE during
startup sequence, Source Frequency 6 will cause port 2 to flash blue TWICE, etc.

b.

All four LEDs on the board will flash red if no source is detected.

3.

Sequentially, each sensor port LED will flash once:
 Green if a sensor is detected, or Red if no sensor is detected.

4.

All LEDs turn OFF (dark) as the boot process completes.

Runtime Sensor port LEDs:
Green:Red:
Blue:
Alternating Green/Blue:
Sensor board LEDs blink red:

URM18PH392 Rev A. May 2020

Sensor Active
Sensor Inactive or out of range.
Sensor FTT® is engaged. (Requires FTT® mode to be enabled. See Section 2.1.)
Sensor FTT® is on but not engaged until sensor is “Homed.” (See Section 2.1.)
Duplicate source frequencies detected on blinking sensor boards; tracker
cannot start.

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USER MANUAL
1.2.2 SENSOR
Position and Orientation (P&O) is calculated at the EM center of the Sensor device, relative to a Cartesian origin
location in the motion tracking area. By default, this reference location is at the EM center of a VIPER™ Source,
so all calculated Sensor P&O is relative to that Source. Alternatively, the reference location may be defined by
the user, selected for the specific needs of the application. Refer to Sections 3.5 “Configuring VIPER™ multisource modes of operation“ and 4.2.14 “SOURCE CONFIGURATIONS AND MODES OF OPERATION“ for details
about this.
The VIPER™ Sensor is available in multiple styles, including:

FT-Standard: with mounting holes
FT-Flatsided: without mounting holes
FT-Clip: with tapered edges that fit into a mounting clip

The Sensors connect easily to the SEU via reversible plugs so the orientation of the connector does not matter
when plugging in.
See Appendix C for Sensor dimensions.

FIGURE 5. VIPER™ SENSORS. FROM TOP: FT-STANDARD, FT-FLATSIDED, AND FT-CLIP (WITH CLIP SHOWN)

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USER MANUAL
1.2.3 STYLUS
The Stylus is a pen-shaped device that is tracked positionally in three dimensions as well as angularly. A pushbutton switch is integrated to give the user control of the data output. Stylus position measurements arecalculated at the tip of the Stylus, using precise factory calibration. The tip is removable/replaceable andavailable with a sharp point (standard) tip or a rounded tip. The Stylus is available in two sizes: 3 inches long
(FT3-Stylus) and 8 inches long (FT8-Stylus).

FIGURE 6. VIPER™ FT3-STYLUS AND FT8-STYLUS

1.2.4 SOURCEThe VIPER™ Source emits the electromagnetic field (EM field) necessary to track the P&O of Sensors within
range. The three-dimensional space in which the EM field is detectable by the Sensors is known as the motion
tracking area. Multiple Sources may be used to define and expand this area. When more than one Source isused, each Source must operate at a different frequency so that it can be distinguished from the others by the
Sensors. (Source frequency is not a configurable feature; Sources are manufactured to operate at specificfrequencies and may be purchased accordingly.)
In a standard installation, the Source is usually the reference for Sensor P&O measurements. The Source ispowered by the SEU and is connected at the dedicated Source connection port(s). Up to four sources can be used
in a single VIPER™ system.
The Source is usually mounted in a fixed position to a non-metallic surface or stand located in close proximity to
the Sensors.
VIPER™ Sources are available in a variety of form factors and EM frequencies. The standard TX2 Source is a 2-inch
cube. Other sizes available include TX4 (a 4-inch cube) and several smaller sizes, including the HR-Source. The
larger sized Sources emit a stronger field that can be detected from farther away by the standard Sensors. The
smaller sized Sources have a proportionally weaker field and are useful where close proximity and smaller form
factor are needed. Specifications in this manual are based on the standard 2-inch Source.
See Appendix C for approximate Source dimensions.

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USER MANUALFIGURE 7. VIPER™ TX2 SOURCE

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USER MANUAL
2. OPERATIONWith the ability to drive multiple Sources and sixteen Sensors, VIPER™ can be operated in many configurations.
Modes of operation can be configured on a per-Sensor basis. Typical modes of operation are described below.
Standard Single-Source operation: A single Source is used. All Sensor position and orientation (P&O) is referenced
to that one Source. On a VIPER™ 8 or VIPER™ 16 system, the one Source must be connected to Source port 1.
This is the traditional way that most legacy Polhemus trackers operate.
Standard Multi-Source modes of operation: Two, three, or four Sources of differing frequencies are used on a
VIPER™ 8 or VIPER™ 16 system. Each Sensor P&O is referenced to the nearest connected Source. In this mode,
one VIPER™ system can effectively behave as the equivalent of up to four individual and independent
conventional tracking systems. This is a new and unique capability of VIPER™ over earlier tracking systems. These
modes of operation are discussed in detail in Section 3.5.
Expanded Multi-Source operation: Multiple Sources are configured together to define an expanded tracking
area. By default, each Sensor operates with all Sources. If desired, each Sensor may be configured to operatewith any combination of Sources.
VIPER™ Sensor and Source configuration commands allow the user to configure and modify these basic modes ofoperation. These commands and modes of operation are discussed in detail in Sections 3.5 and 4.2.13 below.

2.1 FTT® MODE
FTT® (Fly True Technology) is a revolutionary real-time magnetic distortion mitigation method exclusive to
Polhemus. The benefits are most noticeable in a tracking environment with electromagnetic distorting
conditions, namely the presence of certain conductive metals that support magnetic eddy currents. These
conditions, when in proximity to the Sensor or Source can cause errors in the position and orientation outputs
from the VIPER™ tracking system until removed.
HOW IT WORKS:
FTT® Mode is an iterative filter that uses measured magnetic fields emitted from the VIPER™ Source, known
environmental conditions, and electromagnetic hemispheric frequencies detected by the FT Sensor to recognize
the negative influence of magnetic distortion and apply a real-time filtered correction. The resulting tracking
performance can be stunningly good in environmental conditions that might otherwise limit the utility of the
tracker (examples include tracking near large metal objects like desks, filing cabinets, steel walls, and rebar
concrete floors).
To use FTT®, the VIPER™ tracker must have FTT® Mode enabled and the FT Sensor in a “Home” location near a
Source. When FTT® is enabled in this way, the LED light for the FT Sensor port in use on the VIPER™ SEU (System
Electronics Unit) will be green in color. The LED will blink in a green and blue pattern until “Homing” hasoccurred.
As the FT Sensor is moved away from the Source or a distortion-inducing object is brought close to the FT Sensor
or Source, FTT® will engage and the LED light for the FT Sensor port in use will turn blue. FTT® is now actively
working to sense the electromagnetic distortion and apply a correction filter in real-time to the Position andOrientation tracking output. FTT® corrects for both position and orientation data output.

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FTT® should start with the Sensor in “Home” location and with the FT-Sensor’s
SEU Sensor port in a GREEN LED state. The Sensor port LED will alternate
GREEN and BLUE until Sensor is “Homed” this way.
At introduction, VIPER™ FTT® has two modes of operation: Stationary Source Mode for conventional tracking
applications where VIPER™ Sources are mounted in a fixed position and Moving Source Mode where VIPER™
Sources may be used in innovative dynamic and diverse scenarios. Be sure to understand the difference
between the modes and select the best one for your tracking applications. Refer to Section 4.2.12 FTT MODE
command for details about the available FTT® modes.
Both FTT® modes will “carry” the high-quality tracking performance of the VIPER™ tracker in difficult conditions
for a period of time but due to the iterative nature of the filter, it is necessary to periodically return the FT Sensor
to Home in order to effectively reset the tracker’s measurement quality factors.
FTT® is a real-time distortion mitigation correction.
Due to the iterative nature of this feature, FTT® can cause tracking output tobe less precise in magnetically benign tracking environments than without it.
FTT® is a solution to a problem, but if no problem is present, it may be best
not to engage at all so that tracking solution variables are minimized. Users
may decide to leave FTT® Mode OFF in many situations depending upon
tracking quality needs.

2.2 I/O CONSIDERATIONSVIPER™ has two communication I/O ports: USB and RS-422. The USB port uses a micro USB connector. The RS422 port uses a Micro D 9-pin plug connector (male, Molex part number 836119006). The pinout is shown in
Figure 8 below.
Either I/O port can be used for command input and data output. When the VIPER™ is powered ON, either port
will respond to commands when used as a single output port.
VIPER™ also supports a dual-output mode where the tracker data stream is output to both ports. In this mode, it
is recommended that the USB port be used for command input (as well as data output) and the RS-422 port bemonitored only for output data.

1
2
3
4
5

TX+

RX+
GND

6
7
8
9

TXReset
RX-

Micro D 9-pin Plug, Molex part 83611-9006

FIGURE 8. PINOUT VIPER™ RS-422 MALE CONNECTOR

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2.3 EXTERNAL SYNC
The VIPER™ External Sync port accepts a standard USB Type C connector. Pins A7 and B7 are the active sync pins
as illustrated in Figure 9 below.
Functionally, VIPER™ External Sync hardware can operate in two modes. These modes are configured using the
SYNC MODE command, detailed in Section 4.2.3.
Internal Sync Mode: A 3.3V sync pulse is output simultaneously with each P&O frame output. The pulse has
duration of 10µs and occurs at the beginning of the data collection cycle. This is the default mode.
External Sync Mode: When the external device applies a ground pulse (minimum duration of 10µs), P&O
computation is initiated using sensor data immediately preceding the ground pulse.

FIGURE 9. VIPER™ EXTERNAL SYNC PINOUT

2.4 SOFT RESET
Pin 7 on the RS-422 connector port can be used to soft-reset the SEU. Apply GND to this pin for duration of 10ms
to force a soft reset.

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3. GETTING STARTED
3.1 SETTING UP VIPER™ HARDWARE FOR THE FIRST TIME
When setting up VIPER™ for the first time, it is highly recommended that you start by experimenting with one
Source and a couple of Sensors in a standard configuration before moving on to more complex installations withmultiple Sensors and Sources.

3.1.1 MAKE CONNECTIONS
Refer to the figure below for connecting your VIPER™ components together.

FIGURE 10. GETTING STARTED: CONNECTIONS

1.
2.
3.
4.

Place the SEU near the host computer.
Attach one or two Sensors in Sensor ports 1 and 2.
Attach a Source to Source port 1.
Connect the VIPER™ power supply to the 5V DC IN port on the rear panel.

3.1.2 PLACE SOURCE AND SENSOR(S)When placing Source and Sensors for the first time (when VIPER™ is configured with factory default settings), it isimportant to place the Sensors on the +X side of the source. This places the Sensor in the +X hemisphere of the
Source. The +X and +Y axes are identified on the surface of the standard Source cube to help you identify wherethe +X side of the Source is. This is illustrated in Figure 11 below.
If your sensor is not in the default +X hemisphere, use the HEMISPHERE
command (Section 4.2.9) to tell VIPER™ which hemisphere the Sensor inhabits
or to turn on Auto-Hemisphere.

See Appendix B SOURCE HEMISPHERES for a detailed discussion of the concept of hemispheres.

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USER MANUALFIGURE 11. SENSOR PLACED IN +X HEMISPHERE

3.2 INSTALL HOST SOFTWARE (WINDOWS®)
VIPER™ Host Software is provided on a USB thumb drive or is downloaded from the Polhemus website. Run
VIPER_Installer.exe to install all of the necessary drivers and software. Review VIPER_RELEASE_NOTES.htm for
information about what is contained in the Host Software distribution.
To access non-Windows® and developer content, follow instructions displayedin the VIPER™ Host Software Release Notes.

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3.3 RUN VIPER™ COMMAND MANAGER
Start the VIPER™ Command Manager (VPcmdMgr) application by clicking the
Host Software.
On Windows® 10, this icon will appear in the Start Menu

For easy access to the VPcmdMgrclick and select Pin to Start.

icon that was installed with theunder “Recently Added:”icon directly under the Windows® 10 Start Menu, right-→

3.3.1 UPDATE VIPER™ COMMAND MANAGER
After installing VIPER™ Command Manager for the first time, check for available updates to the program.

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3.4 VIPER™ COMMAND MANAGER USER INTERFACE OVERVIEW
On startup, the VIPER™ Command Manager app (VPcmdMgr) connects automatically to VIPER™ and collects asingle frame of P&O data.

On the Status Pane at the left, icons for the VIPER™ SEU
and connected Sensors and/or Stylus’
aredisplayed. Different colored Sensor/Stylus icons correspond to animated avatars in the Graphics Pane to theright.
In the Graphics pane, the sensor avatars are displayed with +X pointing out of the screen toward
the viewer’s eye. This corresponds to looking at the sensor(s) and source from the direction of
the +X axis.

When the mouse pointer is hovered over active
controls in the app, the mouse pointer will change
and a descriptive tool tip will appear. Use thisfeature to discover active controls in VPcmdMgr:

For example, to view
“Who Am I” information
about the VIPER™
device, click on the
VIPER® iconin theStatus Pane.

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3.4.1 DISPLAYING VIPER™ P&O DATA

To collect and display a single frame of data, click onin the toolbar or type p.

To collect and display continuous streaming data, click onin the toolbar or type c.

P&O data is displayed in text format in the Text Pane and graphically by animated avatars in the Graphics Pane.
By default, VIPER™ outputs SEU number and Sensor number, Frame Number, Position in inches and Orientationin Euler Degrees.

Hover the mouse pointer over the title bar in the text pane to see what data is currently displayed.

Right-click the mouse over the title bar in the text pane to select data to be displayed.

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3.4.2 CONFIGURING VIPER™
To configure VIPER™ settings, click on the
Status Pane.

icon in the

The Status Pane changes color and enters Edit Mode.

3.4.2.1 C OMMONLY USED SETTINGSIn Edit Mode, the Status Pane displays checkboxes next to the VIPER™ SEU
icon and next toeach connected Sensor. A series of control icons for configuring VIPER™ are displayed next to these.

icons forThe most commonly used settings are accessible directly from these controls. Hover the mouse pointer overthese controls to discover which settings are available
here.
The controls are defined below.

SEU-Level Settings:

Sensor Level Settings:

SEU settings apply tothe selected SEU in
the Edit-mode
Status Pane.

When applied, Sensor-levelsettings will be applied to all
selected Sensors in the Edit-Mode
Status Pane.
If the SEU is checked, Sensor-levelsettings are applied to all sensor
ports: all sensors on the SEU,
connected or not.

Source Rotation

Sensor Boresight.
Right-click to RESET.

Units of Measure

Sensor Filter Settings

All SEU Settings (Advanced; See
Section 3.4.2.2 “Advanced settings”
below.)

Sensor HemisphereSensor FTT® Mode
All Sensor Settings (Advanced;
See Section 3.4.2.2 “Advanced
settings” below.)

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3.4.2.2 A DVANCED SETTINGSThe Advanced Settings controls provide access to all available VIPER™ settings in a single “block” display.
Each time the Advanced Settings control is clicked, the tracker is queried to display all of the current settings.
Hover the mouse pointer over buttons in the toolbar at the top of the panel to identify the function of eachbutton, also described in the table below:
Refresh from device. Re-queries VIPER™ for current settings; overwrites any un-applied changes
displayed in the panel.
Apply changes. Sends commands to VIPER™ to change settings. This button is disabled until achange has been made in the settings below.
Reset. Sends RESET commands to VIPER™ to restore all displayed settings to factory defaults. The
panel is refreshed to display the factory defaults.

Inside the Block Config panels, click on the listed properties to display information about each setting and default
values in the bottom portion of the display as illustrated in Figure 12 below.

FIGURE 12. SEU AND SENSOR BLOCK CONFIGURATION PANELSURM18PH392 Rev A. May 2020

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USER MANUALThe Block Configuration Panels have several controls tomanipulate the display.
1.

Click in any field to see reference information about
the VIPER™ setting it controls in the description paneat the bottom.

2.

Click on the + and – buttons to expand and collapse
groups of settings.
3. Columns and rows are resizable vertically andhorizontally. Click on boundaries between panes toactivate resizing handles.

3.4.2.3 P ERSISTENCE
With few exceptions, the settings accessed through the Advanced
Block Config panels are persistent settings.
This means that these settings can be stored in VIPER™ flash memory.
Stored persistent settings are activated each time VIPER™ is powered
ON. To store the currently active settings to flash, select Device
Menu→Persist Current Configuration.
To revert to factory default configuration, select Reload Default
Configuration. Then, to restore factory settings to flash memory, select Persist Current Configuration again.

3.4.3 KEYBOARD SHORTCUTS
VIPER™ Command Manager keyboard shortcuts are not case-sensitive.
TABLE A. VIPER™ COMMAND MANAGER KEYBOARD SHORTCUTS

B.............................. Apply Boresight command to all Sensors
Control-B ................. Un-boresight all Sensors
C .............................. Toggle Continuous data streaming
Control-E ................. Display Event Log Pane
Delete key ............... Clear Text Pane
Shift-Delete ............. Clear Event Log Pane
P .............................. Collect a Single frame of P&O data
Q ............................. Toggle FTT® Mode ON/OFF for all Sensors
F2 ............................ Zoom IN
F3 ............................ Zoom OUT← ............................ Rotate scene clockwise about the vertical screen axis
→ ............................ Rotate scene counter-clockwise about the vertical screen axis
↓ ............................ Rotate scene toward the eye about the horizontal screen axis
↑ ............................ Rotate scene away from the eye about the horizontal screen axis

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3.5 CONFIGURING VIPER™ MULTI-SOURCE MODES OF OPERATIONAs described previously in Section 2. , VIPER™ is able to drive up to four Source components.
Note: When multiple Sources are used, each Source must operate at adifferent electromagnetic (EM) frequency.
If multiple Sources of the same frequency are connected, VIPER™ will not
operate.
Polhemus offers Sources in a variety of EM frequencies.
When VIPER™ powers up, it detects plugged in Sensor and Source components. (Hot swapped Sensors are also
detected when plugged in while VIPER™ is running.)
Depending on the pattern of connected Sources, VIPER™ defaults to one of several standard modes of operation.
These modes are detailed in the following Sections 3.5.1, 3.5.2, and 3.5.3.
Each mode is characterized by: Which Source(s) the Sensor detects for determining position and orientation (P&O)
and Which Source is the referenced Cartesian origin (0, 0, 0) and null orientation.

3.5.1 SINGLE-SOURCE MODE

Applies to VIPER™ 8 and VIPER™ 16 systems.
One Source is plugged into Source port 1.
All Sensors report P&O relative to Source 1.
No Source is plugged into any other Source port.

3.5.2 DUAL-SOURCE MODE

FIGURE 13. VIPER™ 16 SINGLE-SOURCE MODE

Each group of 8 Sensors report P&O with respect to Sources 1 and 3. In this mode, VIPER™ behaves as two
independent 8-Sensor tracking systems.







Applies to VIPER™ 16 systems only.
Two Sources are plugged into Source ports 1 and 3.
Sensors 1-8 report P&O relative to Source 1.
Sensors 9-16 report P&O relative to Source 3.
Sources 1 and 3 must operate at different EM frequencies*.
No Source is plugged into Source ports 2 and 4.

FIGURE 14. VIPER™ 16 DUAL-SOURCE MODE

*See warning note above.

3.5.3 LOCAL-SOURCE MODE
Each group of 4 Sensors report P&O with respect to the Local Source. Refer to Figure 15 and Figure 16 below to
see the location of Local Sources.
Applies to all VIPER™ systems; this is the standard operating mode for VIPER™ 4.
On a VIPER™ 8 system:






Behaves as two independent 4-Sensor systems.
Two Sources are plugged in to Source ports 1 and 2.
Sources 1 and 2 must operate at different EM frequencies*.
Sensors 1-4 report P&O with respect to their Local Source: Source 1.
Sensors 5-8 report P&O with respect to their Local Source: Source 2.

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On a VIPER™ 16 system:









Behaves as up to four independent 4-Sensor systems.
Two–four Sources are plugged into Source ports 1-4.
Sources must each operate at a different EM frequency*.
One Source must be plugged into Source port 1.
Sensors 1-4 report P&O with respect to their Local Source: Source 1.
Sensors 5-8 report P&O with respect to their Local Source: Source 2. FIGURE 16. VIPER™ 16 LOCAL SOURCE LOCATIONS
Sensors 9-12 report P&O with respect to their Local Source: Source 3.
Sensors 13-16 report P&O with respect to their Local Source: Source 4.

*See warning note above.
3.5.3.1 N EAREST SOURCE
Viper 16™ flexibility allows variations on the Local- and Single-Source modes. Groups of 4 Sensors report P&O
with respect to the Nearest Source: The Local Source, or if no Local Source is detected, then the first Source
detected on a lower numbered Source Port.


Applies to VIPER™ 16 systems only.
Two or three Sources are plugged into any Source ports 1-4.
One Source must be plugged into Source port 1.
All Sources must operate at different EM frequencies*.

Examples A, B, and C below illustrate three of many possible combinations.
Example A: VIPER™ 16 behaves as independent 4- and 12-Sensor systems.
 Different freq. Sources are plugged into Source Ports 1 and 2.
 Sensors 1-4 report P&O with respect to their Local Source:
Source 1.
 Sensors 5-16 report P&O with respect to their Nearest Source:
Source 2.

FIGURE 17. VIPER™ 16 NEAREST SOURCE, EXAMPLE A

Example B:
 VIPER™ 16 behaves as independent 12- and 4-Sensor systems.
 Different freq. Sources are plugged into Source Ports 1 and 4.
 Sensors 1-12 report P&O with respect to their Nearest Source:
Source 1.
 Sensors 13-16 report P&O with respect to their Local Source:
Source 4.
Example C:

FIGURE 18. VIPER™ 16 NEAREST SOURCE, EXAMPLE B

 VIPER™ 16 behaves as three independent 4-, 8- and 4-Sensor systems.
 Different freq. Sources are plugged into Source Ports 1, 2, and 4.
 Sensors 1-4 report P&O with respect to their Local Source:
Source 1.
 Sensors 5-16 report P&O with respect to their Nearest Source:
Source 2.
 Sensors 13-15 report P&O with respect to their Local Source:
Source 4.

*See warning note above.

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FIGURE 19. VIPER™ 16 NEAREST SOURCE, EXAMPLE C

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3.5.4 CUSTOM MULTI-SOURCE MODE CONFIGURATION
For applications in which the standard Single- Dual- and Local-Source mode are not quite right, VIPER™ can be
configured to operate in a custom user-selected Multi-Source mode.
Multi-Source behavior is defined on a per-Sensor basis by two settings that may be manually configured:
SOURCE SELECT defines which Source(s) a Sensor detects for determining P&O.
SENSOR ORIGIN defines which Source serves as the Sensor’s referenced Cartesian position origin (0, 0, 0) andnull orientation.
Both of these settings are configured using VIPER™ configuration commands SOURCE SELECT and SENSORORIGIN. These commands and settings are detailed in Section 4.2.14.

3.5.5 EXPANDED TRACKING AREA MULTI-SOURCE MODE
In the previous three modes of operation, connected VIPER™ Sources are used as individual units, each one
defining a separate frame of reference for Sensor P&O. As such, each “Source tracking volume” is limited in sizeand shape by the strength of the EM field emitted by that Source.
For applications that require an expanded tracking area, the connected VIPER™ Sources can be configured
together to define a single expanded tracking volume and frame of reference for all Sensors.
The SOURCE CONFIGURATION command allows the user to specify the position and orientation of eachconnected Source relative to a user-defined virtual frame of reference. The reference frame may correspond to
one of the Sources or it may be a virtual point implied by the position configurations for the Sources in thesystem. The SOURCE CONFIGURATION command is detailed in Section 4.2.7.
Note: VIPER™ operates in Expanded Tracking Area Mode whenever SOURCECONFIGURATION is applied to the system, regardless of the pattern ofconnected Sources.

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3.6 USING A STYLUS WITH VIPER™
To use the VIPER™ Stylus as a point digitizer:
1.

Set the SEU Stylus Mode setting to Point Mode.
a.

Enter Edit Mode by clickingb.

Display Advanced SEU configuration settings by clicking

c.

Select Stylus Mode→Point.

Click on the Apply Changes
Config Pane.

.
.

button at the top of the SEU Block

The Digitizer Mode icon
will display in the Status Bar at thebottom of the screen and on the Status Pane next to the SEU glyph.

2.

Now start VIPER™ Continuous Mode by clicking

or typing c.

Now in Continuous Mode with Stylus Point Mode enabled, each press of the Stylus button will produce one
frame of data in the VIPER™ Command Manager display.
To make VIPER Command Manager emit an audible tone when the stylus button
is pressed, enable Audible Stylus Marker in VIPER Command Manager Options
from the Tools Menu.

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4. VIPER™ COMMAND INTERFACE
The purpose of this section is to describe VIPER™ configuration settings and other commands. These settings areapplied to the system via the VIPER™ command interface, which defines the commands, actions, andconfiguration data used to interact with the tracker device.
VIPER™ commands can be applied to the device with the VIPER™ Command Manager or directly via the USB or
RS422 I/O channel with a user-developed custom application.
For application development, Polhemus offers an open-source Standard C++ SDK conforming to C++14 corelanguage features. Refer to online developer resources for details on the use of the VIPER™ command interface
directly or with these VIPER™ SDK libraries. Links to online developer resources are provided in the Release Notesof the VIPER™ Host Software installation media.

4.1 COMMAND SUMMARY
VIPER™ commands fall into a variety of categories:Command is applied per-SEU or per-Sensor.
Some commands are Executive in nature in that they perform executive actions on the running SEU.
Some are Get-only, reporting the current state of the system or version and/or serial numbers.
Configuration commands may pertain to persistent or not-persistent configuration settings.

The tables below list the main user commands and summarize their scope and function.
TABLE B. CONFIGURATION COMMANDS - PERSISTENT

Command
FRAME RATEUNITSSYNC MODESTYLUS MODESEU ID
SOURCE ROTATIONSOURCE CONFIG
PREDICTION FILTERHEMISPHEREFILTER
INCREMENTFTT MODEVIRTUAL SENSOR
SOURCE SELECTSENSOR ORIGIN

Actions
Get/Set/Reset
Get/Set/Reset
Get/Set/Reset
Get/Set/Reset
Get/Set/Reset
Get/Set/Reset
Get/Set/Reset
Get/Set/Reset
Get/Set/Reset
Get/Set/Reset
Get/Set/Reset
Get/Set/Reset
Get/Set/Reset
Get/Set/Reset
Get/Set/Reset

Scope
SEU
SEU
SEU
SEU
SEU
SEU
SEU
sensorsensorsensorsensorsensorsensorsensorsensorSection
4.2.1
4.2.2
4.2.3
4.2.4
4.2.5
4.2.6
4.2.7
4.2.8
4.2.9
4.2.104.2.114.2.124.2.134.2.14.1
4.2.14.2

TABLE C. CONFIGURATION COMMANDS -- NOT PERSISTENT (RUN-TIME ONLY)

Command
RS-422 SERIAL CONFIG
DUAL OUTPUT MODETIP OFFSET

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Actions
Get/Set/Reset
Get/Set/Reset
Get/Set/Reset

Scope
SEU
SEU
sensorSection
4.3.1
4.3.2
4.3.3

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Command
BORESIGHT

Actions
Get/Set/ResetScopesensorSection
4.3.4

Scope
SEU
SEU

Section
4.4.3
4.4.4

Scope
SEU
SEU
SEU
SEU
sensorsourceSection
4.5.1
4.5.2
4.5.3
4.5.4
4.5.5
4.5.6

Scope
SEU
SEU
SEU

Section
4.6.1
4.6.2
4.6.3

TABLE D. P&O COMMANDS

Command
SINGLE PNO
CONTINUOUS PNO

Actions
Get Only
Set/Reset

TABLE E. READ-ONLY COMMANDS

Command
BIT RESULTSSTATION MAP
MAP STATUS
WHO AM I
SENSOR WHO AM I
SOURCE WHO AM I

Actions
Get Only
Get Only
Get Only
Get Only
Get Only
Get Only

TABLE F. EXECUTIVE COMMANDS

CommandPERSISTBLOCK CONFIGENABLE MAP

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Actions
Set Only
Reset Only
Set/Reset

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4.2 CONFIGURATION COMMANDS, PERSISTENT
4.2.1 FRAME RATE COMMAND
This command sets the update rate of frames per second. The frame rate can be set to 30Hz, 60Hz, 120Hz, or
240Hz for all VIPER™ SEUs. VIPER™ 8 and VIPER™ 16 systems may also be set to output data at 480Hz or 960Hz.
In VIPER™ Command Manager, Frame Rate isconfigured in the SEU Block Config panel in the
Output group.
Access the SEU Block Config panel by selecting
to the right of the VIPER™ SEU icon
Mode Status Pane.

in the Edit

Default: 240Hz
Scope: SEU
Persistent: YES

4.2.2 UNITS COMMAND
This command sets the Position and Orientation output units.


Position Cartesian coordinates output units options are Inch, Foot, Centimeter, and Meter.
Orientation output units options are Euler Angle Degrees, Euler Angle Radians, and Quaternion.

In VIPER™ Command Manager, Units are configured
by selecting
in the Edit Mode Status Pane.

Default: Inches, Euler Degrees.
Scope: SEU
Persistent: YES

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4.2.3 SYNC MODE COMMAND
The Sync Mode setting determines how the VIPER™ External Sync hardware works.
Internal Sync: A 3.3V sync pulse is output simultaneously with each P&O frame output. The pulse has duration of
10µs and occurs at the beginning of the data collection cycle.
External Sync: When the external device applies a ground pulse (minimum duration of 10µs), P&O computation
is initiated using sensor data immediately preceding the ground pulse.
In VIPER™ Command Manager, Sync Mode isconfigured in the SEU Block Config panel in the
Other Properties group.
Access the SEU Block Config panel by selecting
to the right of the VIPER™ SEU icon
Mode Status Pane.

in the Edit

Default: Internal
Scope: SEU
Persistent: YES

4.2.4 STYLUS MODE COMMAND
The Stylus Mode setting determines what happens when a Stylus push button switch is pressed.
Marker Mode: Pushing the switch causes a flag (or “mark”) to be set in the output P&O frame for that Stylus.
Point Mode: Pushing the switch causes VIPER™ to emit one frame of P&O data. The data frame includes P&O of
all connected Sensors (not just the Stylus).
Line Mode: VIPER™ outputs continuous P&O data while the switch is pressed. The continuous stream stops when
the switch is released. P&O of all connected Sensors is output.
Toggle Mode: Pushing the switch causes VIPER™ to start or stop continuous data streaming. (This is equivalent
to using the CONTINOUS PNO command.)In VIPER™ Command Manager, Stylus Mode isconfigured in the SEU Block Config panel in the
Other Properties group.
Access the SEU Block Config panel by selecting
to the right of the VIPER™ SEU icon
Mode Status Pane.

in the Edit

Default: Marker Mode
Scope: SEU
Persistent: YES

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4.2.5 SEU ID COMMAND
This command allows you to program a numeric ID into the SEU. The SEU ID will appear in the SEU ID field of
output P&O frames.
In VIPER™ Command Manager, SEU ID isconfigured in the SEU Block Config panel in the
Identification group.
Access the SEU Block Config panel by selecting
to the right of the VIPER™ SEU icon
Mode Status Pane.

in the Edit

Default: SEU ID is zero
Scope: SEU
Persistent: YES

4.2.6 SOURCE ROTATION COMMAND
Note: Do not use the SOURCE ROTATION command when the SOURCECONFIGURATION command is in use (for Expanded Tracking Area Mode).

Source Rotation allows the user to modify the reference frame rotation of the Source(s). It is essentially a nonphysical rotation of the Source and becomes the new orientation reference for each Sensor’s measurements.
Source Rotation is not a Sensor-specific setting and affects the global reference frame of the tracking system.
Source Rotation allows the user to specify the Azimuth, Elevation and Roll of each Source in the system, or all
Sources in the system.
Note: When used in conjunction with the SOURCE SELECT command (Section
4.2.14.1), Source rotation affects the reference frame of only the Sensors that
select that Source.
In VIPER™ Command Manager, Source
Rotation is configured by selecting
inthe Edit Mode Status Pane.

Default: (0,0,0) Azimuth, Elevation, Roll for all Sources
Scope: SEU
Persistent: YES

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4.2.7 SOURCE CONFIGURATION COMMAND
Source configuration allows the user to configure Position and Orientation for all Sources in the Expanded
Tracking Area Mode of operation, detailed in Section 3.5.5. Setting the P&O of each source in this way effectively
defines the frame of reference for Sensor P&O that is output by the tracker.
Source Position and Orientation configured by this command is expressed in current tracker units of measure asconfigured by the UNITS command.
The Startup Hemisphere configured by this command describes the direction with respect to that Source fromwhich Sensors enter the tracking area or approach the Source. At runtime, Sensors begin tracking by detecting
the EM fields emitted by the sources in the tracking area. Correct computation of P&O depends upon priorknowledge about which side of the Source the Sensor is expected to be on when the Source is initially detected.
(This moment of initial detection occurs when the SEU is powered ON.)
Possible Startup Hemisphere values are ±X, ±Y, ±Z or Auto:±X, Y, Z values correspond to the source hemispheres depicted previously in Figure 11.
Auto engages Auto-Hemisphere, discussed below in Section 4.2.9
In VIPER™ Command Manager, Source Configurationis configured in the SEU Block Config panel in theGeometry group.
Access the SEU Block Config panel by selecting
to the right of the VIPER™ SEU icon
Mode Status Pane.

in the Edit

Default: None (Position (0,0,0) and Orientation (0,0,0) Azimuth, Elevation, Roll for all Sources)
Scope: SEU
Persistent: YES
Note: Do not use the SOURCE ROTATION command when the SOURCECONFIGURATION command is in use.
Note: Auto Startup Hemisphere requires FT Sensors to function.
Non-FT Sensors will assume POS X Startup Hemisphere for Source(s) with Auto
Startup Hemisphere configured.

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Example Scenario: SOURCE CONFIGURATIONYour project uses two TX4 Sources placed 6 feet apart. You are tracking a human subject wearing 6
sensors on arms and shoulders. The subject is moving freely between the two sources, which aremounted on tripods 4 feet above the floor. Sources 1 and 2 are facing in the same direction.

You want the Sensors’ P&O reference (origin) to be at the point halfway between the Sources.
You will use the SOURCE CONFIGURATION command to tell VIPER™ the position and orientation ofeach of the two Sources, also referenced to the origin.
Therefore, in our example Source 1 is positioned at (0.0, -36.0, 0.0) inches: It is 3 feet in the –Y
direction from the origin, and it is equal to the origin in X and Z. (Note, the +Z axis extends downward
toward the floor.)
Source 2 is likewise positioned at (0.0, +36.0, 0.0) inches.

Since both Sources’ positive X, Y, and Z axes are parallel to the reference axes, the orientation of bothis (0,0,0) degrees Azimuth, Elevation, Roll.
For Startup Hemisphere for each Source, you will choose AUTO. When the VIPER™ Sensors initiallydetect the Sources, VIPER™ will automatically detect and track the Sensors’ hemisphere of operation.
(See Section 4.2.9 HEMISPHERE command for an explanation of the Auto-Hemisphere feature.)

Finally, you will want to execute the PERSIST command to save these settings to VIPER™ FLASH memory sothat when VIPER™ reboots, the settings will persist.

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4.2.8 PREDICTION FILTER COMMAND
The PREDICTION FILTER command enables and disables the VIPER™ Prediction Filter for Position and/or
Orientation tracker data.
When enabled, VIPER™ predicts current and future Sensor P&O based on previous P&O data. Prediction time isconfigurable from 1ms.
In VIPER™ Command Manager, Prediction Filter isconfigured in the Sensor Block Config panel in thePrediction Filter group.
Access the Sensor Block Config panel by selecting
to the right of a Sensor iconin the Edit
Mode Status Pane.

Default: Disabled for both Position and Orientation. Default time is 20ms
Scope: Sensor
Persistent: YES
Note: Operating the tracker with maximum capacity Sensors and Sources at
the highest FRAME RATE (960Hz) and Prediction Filter enabled on multiple
Sensors may cause a slight reduction in actual frames-per-second output.

4.2.9 HEMISPHERE COMMAND
This command allows the user to configure the VIPER™ Auto-Hemispherefeature or to manually configure Sensor hemisphere of operation.
Hemisphere of operation is the half of the sphere surrounding the Source thatcan be used at any one time without ambiguity in the sign of a Sensor’s
reported X, Y, Z measurements. This is due to the symmetry of magnetic fields
emitted by the Source. For more information about this phenomenon, see
Appendix B. SOURCE Hemispheres.
Automatic Hemisphere Detection
With FT-Sensors, VIPER™ automatically detects and tracks Sensor hemisphere ofoperation when Auto-Hemisphere is enabled.
Note: The FT-Sensor must move initially for AutoHemisphere detection to engage.
Manual Hemisphere Configuration
Without Auto-Hemisphere, X, Y, Z sign ambiguity can occur if correct hemisphere of operation is not manuallyconfigured.

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Further, each Sensor can operate correctly on only one side of a Source, unless Hemisphere Tracking is used.
With Hemisphere Tracking enabled, VIPER™ continuously modifies the operating hemisphere, allowing fulltracking coverage around all sides of the Source.
Note: To start Hemisphere Tracking, VIPER™ must be operating in a known,
valid hemisphere. That is, the Sensor must be located in the currently
configured hemisphere of operation.
Note: Hemisphere Tracking is automatically enabled with Auto-Hemispheredetection.
For Expanded Tracking Area Multi-Source configurations (Section 3.5.5), Startup Hemisphere is configured with
the SOURCE CONFIGURATION setting (Section 4.2.7).
In VIPER™ Command Manager,
Hemisphere is configured by selecting
in the Edit Mode Status Pane.

Default: +X for all Sensors
Scope: Sensor
Persistent: YES, except Hemisphere Tracking, unless Auto-Hemisphere is enabled.
Note: If Auto-Hemisphere is applied to a non-FT Sensor, VIPER™ responds to the
HEMISPHERE command with a warning, and Auto-Hemisphere is not engaged
on that sensor. Instead, Hemisphere Tracking is enabled on that Sensor and the+X Hemisphere is assumed.
If the Auto-Hemisphere was previously enabled and the detected Sensor is not
an FT Sensor, the default Hemisphere Tracking will be enabled and +X starting
Hemisphere will be assumed.

4.2.10 FILTER COMMAND
VIPER™ employs optional filtering that is designed to control noise (jitter) in the P&O data output. Filters can beapplied to position or orientation or both. The FILTER command is applied on a per-Sensor basis.
Traditional Polhemus Adaptive Filter
The FILTER command establishes the sensitivity, boundary, and transition control parameters for the Traditional
adaptive filter that operates on the position and orientation outputs of the VIPER™ system. The user can adjust
the parameters of this filter to fine-tune the overall dynamic response of VIPER™ or select pre-configured
presets. The definitions of these parameters and presets are detailed in Table G. and Table H. below.

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USER MANUALTABLE G. ADAPTIVE FILTER PARAMETERSF

The sensitivity of the filter to dynamic input conditions. Sensitivity is the proportion of new input
data to recent average data that is used to update the floating filter parameter. The smaller thevalue here, the less sensitive the output becomes to changes in new input data, or the heavier
the filter becomes.
Range: 0 < F < 1.0

F-Low

The maximum allowable filtering to be applied to the outputs during periods of low (static) input
dynamics. A smaller value here allows the output to be less sensitive to changes in new input
data when input data is relatively static. That is, MORE filtering occurs on static data.
Range: 0 < F-Low < F-High.

F-HighThe minimum allowable filtering to be applied to the outputs during periods of highly dynamic
input conditions. A larger value here allows the output to be more sensitive to changes in new
input data when input data is changing rapidly. That is, LESS filtering occurs on highly dynamic
data."
Range: F-Low < F-High < 1.0

F-Max TransThe maximum allowable transition rate from minimum filtering (for highly dynamic input
conditions) to maximum filtering (for relatively static input conditions) by proportionately
limiting the decay to the low filter limit whenever the input conditions effect a transition to anarrower bandwidth. A lower value here slows down the transition from light filtering to heavy
filtering when data dynamics change.
Range: 0 < F-MaxTrans < 1.0
TABLE H. VIPER™ ADAPTIVE FILTER PRESETSFILTERPRESET
None
Light
MediumHeavy
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SENSITIVITY
(F)
n/a
0.2
0.05
0.02
User-specified

BOUNDARY(F-LOW)
n/a
0.2
0.05
0.02
User-specified

BOUNDARY(F-HIGH)
n/a
0.8
0.05
0.02
User-specified

MAX TRANSITION RATE
(F-MAX TRANS)
n/a
0.95
0.95
0.95
User-specified

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About Polhemus Traditional Adaptive Filters

The Traditional filter used by VIPER™ is a single-pole, low-pass filter with an adaptive polelocation. The pole location is constrained within user-specified boundary values F-Low and
F-High but is continuously self-adaptive between these limits as a function of a userspecified sensitivity parameter F and the sensed input conditions (ambient noise plus
rotational rate). For input “rate” conditions that fall within the adaptive range, the adaptive
feature varies the pole location between the F-Low and F-High limits to maximize theoutput resolution for static inputs while minimizing the output lag for dynamic inputs.
Whenever the input conditions cause the filter to make a transition to a narrower
bandwidth (i.e., increased filtering), the transition rate of the pole location is constrained toa user-specified maximum allowable rate (F-Max Trans).

Enhanced Filter
VIPER™ Enhanced Filter mode is now available with FT Sensors. The added capabilities of FT Sensors lead to a
powerful new filtering mode that has excellent characteristics with respect to low noise and low latency.
Enhanced Filters have pre-configured Light, Medium and Heavy presets available. These are identified as E-Light,
E-Medium and E-Heavy in the Filter Settings controls.

In VIPER™ Command Manager, Filters are
configured by selecting
in the Edit Mode
Status Pane.

Default: Traditional Medium for Position and Attitude, all Sensors
Scope: Sensor
Persistent: YES

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Note: If the FILTER command is used to set the Enhanced Filter on a non-FT
Sensor, VIPER™ responds to the command with a warning and the Traditional
Medium Filter is enabled for that Sensor.
If the Enhanced Filter was previously enabled and the detected Sensor is not an
FT Sensor, the default Traditional Medium filter will be engaged.

4.2.11 INCREMENT COMMAND
When enabled, INCREMENT operates in one of two modes:
Fixed-Threshold: New P&O data is reported when changes in position and/or orientation have satisfied the userdefined movement threshold. (Unchanged P&O data is output until movement threshold is satisfied.)
Auto-Threshold: VIPER™ continuously evaluates electromagnetic (EM) signal strength and noise in theenvironment and dynamically and automatically establishes increment thresholds based on those conditions.
Refer to the Example Scenario below for a more detailed description of the difference between Fixed- and AutoThreshold.
Fixed Increment thresholds are expressed in current tracker units of measure as configured by the UNITS
command.
In VIPER™ Command Manager, Increment isconfigured in the Sensor Block Config panel in the
Increment group.
Access the Sensor Block Config panel by selecting
to the right of a Sensor iconin the Edit
Mode Status Pane.

Default: Disabled for both Position and Orientation
Scope: Sensor
Persistent: YES

4.2.12 FTT MODE COMMAND
This command configures the VIPER™ FTT® Mode on FT Sensors. At initial release, FTT® has two modes ofoperation. Be sure to understand the difference between the modes and select the best one for your tracking
applications.
Stationary Source Mode: This mode is for configurations that involve VIPER™ Sources that do not move in 3D
space during tracking (for example, a Source mounted in a fixed location on a wall in a building or on a table;suspended from a ceiling; or embedded in a static position inside a manikin).

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Moving Source Mode: This mode is for dynamic configurations that involve VIPER™ Sources that do move in 3D
space during tracking. Moving Source Mode is useful in diverse applications such as:

a small size TX1 Source embedded in an ultrasound wand that moves while in use, ora Source installed within a motion platform simulator, ora Source installed in a moving vehicle.
Note: Moving Source Mode is only applicable to systems operating in Local
Source Mode, where Sensors report P&O relative to their Local Source. To learn
more about Local Source Mode, see Section 3.5.3.

In VIPER™ Command Manager, FTT® mode isconfigured by selecting
Status Pane.

in the Edit Mode

FTT® Stationary Source Mode can be enabled anddisabled for all Sensors by typing q.

Default: OFF for all Sensors
Scope: Sensor
Persistent: YES
Note: If FTT® Mode is applied to a non-FT Sensor, VIPER™ responds to the FTTMODE command with a warning, and FTT® Mode is OFF on that sensor.
If the FTT® Mode was previously enabled and the detected Sensor is not an FT
Sensor, FTT® Mode will be OFF on that detected Sensor.

4.2.13 VIRTUAL SENSOR COMMAND
This command is used to create or destroy a Virtual Sensor with an unused Sensor number. VIPER™ outputs
P&O for a Virtual Sensor from a configured Input, which is selected from available connected live (active)
Sensors. Once created, a Virtual Sensor may be configured just like an active Sensor—this is useful for testing,comparing and troubleshooting behavior produced by Sensor
configuration settings.
When creating a Virtual Sensor, the Virtual Sensor’s number ischosen from unused sensor numbers local to the active Sensor
Input. Local sensor numbers are in groups of 4 on the VIPER™
panel as depicted in Figure 20.
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USER MANUALFor example, if a live Sensor 1 is connected, Virtual Sensors 2, 3, and 4
could be created using Sensor 1 as the Active Sensor Input. (Figure 21)

FIGURE 21. VIRTUAL SENSOR EXAMPLE

Note that a live Sensor may be used as Input to “feed” multiple Virtual
Sensors at the same time.

In VIPER™ Command Manager, to create or
destroy a virtual Sensor, right-click on a Sensor
icon in the Edit Mode Status Pane.

Default: n/a
Scope: Sensor
Persistent: YES

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4.2.14 SOURCE CONFIGURATIONS AND MODES OF OPERATION
For more information about these commands, please refer to Section 3.5 “Configuring VIPER™ multi-source
modes of operation.”

4.2.14.1 SOURCE SELECT COMMAND
Note: SOURCE SELECT is an advanced feature that is applicable only in rare andvery specific circumstances.
Each Sensor uses one or more detected Sources for determining P&O. These are the Sensor’s Source Selection.
The default Source Selection in various Multi-Source modes as described in Section 3.5 are determined by which
Sources are plugged into VIPER™.
The SOURCE SELECT command is used to override the default Source Selection when multiple Sources are used.
In VIPER™ Command Manager, Source Select isconfigured in the Sensor Block Config panel in the
Source Select group.
Access the Sensor Block Config panel by selecting
to the right of a Sensor iconin the Edit
Mode Status Pane.
Default: Selected according to detected Sources
Scope: Sensor
Persistent: YES
Note: Sensors should not come closer than approximately 4 inches from
Source(s) that are not in the Sensor’s Selected Source list. Degraded tracking
performance may result temporarily in this case, but the condition will be
resolved when the Sensor is moved away.
For example, a system has connected Sensors 1-12 and Sources 1-3. If Sensor
2 has Source Selection 1 and 2, that means Sensor 2 is using only Sources 1
and 2 for P&O calculation. Sensor 2 should stay at least 4 inches away from
Source 3.

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Example Scenario: SOURCE SELECTYour project design uses different types of Sensors and Sources simultaneously:

10 Micro Sensors in ports 1-10 and 2 TX1 Sources in source ports 1 and 2 for close-range“micro” tracking
6 FT-Standard sensors in port 11-16 and 2 TX4 Sources in source port 3 and 4 for Expanded
Area “macro” tracking.

You want the Micro Sensors to track using only the EM fields emitted by the TX1 Sources.
You want the FT-Standard Sensors to track using only the EM fields emitted by the TX4 Sources.

Because you are using the two TX4 Sources for Expanded Area Tracking you must first apply Source
Configuration settings for Sources 3 and 4. See Section 4.2.7 “SOURCE CONFIGURATION command.”
Then, use the SOURCE SELECT command to configure:

Micro Sensors 1-10 to track using the TX1 Sources 1 and 2.
FT-Standard Sensors 11-16 to track using the TX4 Sources 3 and 4.

Finally, you will want to execute the PERSIST command to save these settings to VIPER™ FLASH
memory so that when VIPER™ reboots, the settings will persist.

4.2.14.2 SENSOR ORIGIN COMMAND
Note: SENSOR ORIGIN is an advanced feature that is applicable only in rare andvery specific circumstances.
The SENSOR ORIGIN command is used to configure the Sensor’s P&O reference.
In VIPER™ Command Manager, Sensor Origin is
configured in the Sensor Block Config panel in the
Sensor Origin group.
Access the Sensor Block Config panel by selecting
to the right of a Sensor iconin the Edit
Mode Status Pane.
Default: The Source local to the Sensor, or Common Origin if SOURCE CONFIGURATION command is applied.
Scope: Sensor
Persistent: YES

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Example Scenario: SENSOR ORIGIN
Your project is a multi-player game that uses 16 FT-Sensors and 4 VIPER™ Sources over an expanded
tracking area.
The SOURCE CONFIGURATION command is applied to establish the position and rotation of each source
relative to a Common Origin.
You want each Sensor to use the expanded tracking area afforded by detecting the EM fields of all the
Sources, BUT you do not want the P&O to be relative to the Common Origin.
Instead, you want to configure each player-group of 4 Sensors to use a different Source as the P&O
reference, with one Sensor in the group using the Common Origin.
Use the SENSOR ORIGIN command to configure the P&O reference of each sensor in each group offour.

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4.3 CONFIGURATION COMMANDS, NOT-PERSISTENT
4.3.1 RS-422 SERIAL PORT CONFIGURATION COMMAND
This command programs the baud rate and parity settings in the VIPER™ UART for the RS-422 I/O port.
Available baud rates:
38,400 baud
57,600 baud
115,200 baud
230,400 baud
460,800 baud
921,600 baud
1,843,200 baud*
3,686,400 baud*
7,372,800 baud*

Available Parity settings
None
Even
Odd

*Note: RS-422 Serial port output has been tested up to 921.6K baud.

The RS-422 Serial Configuration settings are not persistent. If it is necessary to use the RS-422 channel forcommand I/O, the host program must first connect at the default setting and then change the setting to thedesired configuration.
In VIPER™ Command Manager, Serial
I/O Port settings are configured in the
SEU Block Config panel in the I/O Config
group.
Access the SEU Block Config panel by
selectingto the right of the VIPER™
SEU iconPane.

in the Edit Mode Status

Default: 115200 baud, No Parity
Scope: SEU
Persistent: NO

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Host-side RS-422 settings usually also include Data Bits, Stop Bits and Handshaking/Flow Control parameters.
When setting up the Host RS-422 port, use the following additional settings:

8 Data Bits
1 Stop Bit
No Handshake/Flow Control

4.3.2 DUAL OUTPUT MODE COMMAND
This command enables and disables Dual Output Mode described in Section 2.2. By default, VIPER™ emitscommand responses and data to the I/O port from which the command was received. This includes streaming
P&O data. When Dual Output Mode is enabled, P&O data is output to both USB and RS-422 ports. Command
responses are also output to both ports.
In VIPER™ Command Manager, Dual
Output Mode is configured in the SEU
Block Config panel in the I/O Config
group.
Access the SEU Block Config panel by
selectingto the right of the VIPER™
SEU iconPane.

in the Edit Mode Status

Default: Disabled
Scope: SEU
Persistent: NO

4.3.3 TIP OFFSET COMMAND
The TIP OFFSET of a VIPER™ Stylus is the positional offset of the Stylus tip from the electromagnetic (EM) centerof the Sensor coil inside the Stylus handle. Each VIPER™ Stylus is factory calibrated with a tip offset. This allows
the tip of the Stylus pen to act as the measurement reference.
For all other VIPER™ Sensor components, there is no factory calibrated tip offset.
For Stylus and Sensor components, the TIP OFFSET values cause VIPER™ to produce P&O for a point other thanthe electromagnetic (EM) center of the Sensor coil.
Applying the TIP OFFSET command to a Stylus overrides the factory calibrated offset that is read by VIPER™ when
the SEU is started. In most circumstances it is not recommended to apply this command to a Stylus.
Note: Applying the TIP OFFSET command to a Stylus overrides the factory
calibrated offset that is read by VIPER™ when the SEU is started. In mostcircumstances it is not recommended to apply this command to a Stylus.
TIP OFFSET may be useful for a Sensor when the Sensor is mounted on a custom instrument, where the Positionof the tip of the instrument is of interest rather than the Sensor itself.

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USER MANUALTIP OFFSET is expressed in current tracker position units as configured by the UNITS command.
In VIPER™ Command Manager, Tip Offset isconfigured in the Sensor Block Config panel in the
Tip Offset group.
Access the Sensor Block Config panel by selecting
to the right of a Sensor iconin the Edit
Mode Status Pane.
Default: Factory Calibrated
Scope: Sensor
Persistent: No

4.3.4 BORESIGHT COMMAND
This command causes the Sensor to be electronically aligned in orientation (and optionally, position) at thecurrent coordinates and establishes the boresight reference angles for the Sensor. If a “Reset Origin” commandargument is applied, X, Y and Z outputs will equal 0,0,0 at the boresight position. VIPER™ then produces P&O
outputs relative to the reference(s). Any Sensor orientation can be designated as the zero orientation point.
A Sensor may be un-boresighted by RESETTING the command.
In VIPER™ Command Manager:
BORESIGHT is SET for all checked Sensors byselectingin the Edit Mode Status Pane with
the LEFT Mouse Button.
BORESIGHT SET will also reset the current Sensor
position to (0,0,0) by clicking YES in the Sensor
Boresight popup window
BORESIGHT is RESET by clicking
mouse button

with the rightDefault: no boresight
Scope: Sensor
Persistent: NO

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4.4 P&O COMMANDS
Position and Orientation (P&O) commands cause VIPER™ to output P&O data either one frame at a time or in acontinuous stream.
A VIPER™ P&O frame is output via the USB and/or RS-422 connection. Both channels are used if DUAL OUTPUT
MODE is enabled (see Section 4.3.2).
A VIPER™ P&O frame is a binary structure that varies in size, depending on how many Sensors are connected to
the SEU.

4.4.1 STANDARD P&O FRAME
A standard VIPER™ P&O frame contains the information below. VIPER™ Command Manager displays the fields
identified with * by default. The other fields are available for display by configuring the P&O display parameters.

32-bit SEU identifier configured by SEU ID command.
* SEU ID ..................................................
32-bit number of frames tracked since the SEU was powered on, or since* SEU Frame number .............................
frame count was reset. See Frame Count Resetbelow.
Sensor count .......................................
32-bit number of Sensors’ P&O data that is contained in the frame
For each reporting Sensor:*

Sensor number ...............................
7-bit numeric reflecting the SEU sensor port that the Sensor is plugged into.

*

Sensor button states ......................
2-bit states of any button switches integrated into the Sensor. A VIPER™
Stylus uses one of these bits.
Distortion level ...............................
8-bit numeric distortion level detected by the Sensor in levels 0-255.
Auxiliary digital input value ...........
10-bits of available data input for custom integrated hardware.

*

Sensor Position (X, Y, Z) .................
32-bit floating point Cartesian coordinates in position units configured by
the UNITS command.

*

Sensor Orientation .........................
Expressed as (3) or (4) 32-bit floating point values for Euler Angles(Azimuth, Elevation, Roll) or a 4-term Orientation Quaternion Q(w, x, y, z)*,as configured by the UNITS command.
[*Note the order of Quaternion components: Scalar value w is output first.]

The output summary above is not an exact representation of the byte structure of the P&O frame. Developers
will require exact frame specification provided in developer resources. Links to online developer resources areprovided in the Release Notes of the VIPER™ Host Software installation media.
Frame Count Reset
Frame Count may be reset in the CONTINUOUS PNO command by providing an argument to the command. In the
VIPER™ Command Manager, this is performed automatically each time Continuous Data is started.

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Right-click the mouse over the title bar in the text pane to select data to be displayed.

4.4.2 ALTERNATIVE P&O FRAME WITH ACCELERATION
VIPER™ has the ability to output P&O in an alternative data mode that includes Sensor acceleration in X, Y, Z axes
and magnitude.
A VIPER™ P&O frame with acceleration data contains the fields below. VIPER™ Command Manager displays thefields identified with * by default. The other fields are available for display by configuring the P&O display
parameters.

32-bit SEU identifier configured by SEU ID command.
* SEU ID ..................................................
32-bit number of frames tracked since the SEU was powered on, or since* SEU Frame number .............................
frame count was reset. See Frame Count Resetabove.
Sensor count .......................................
32-bit number of Sensors’ P&O data that is contained in the frame.
For each reporting Sensor:*

Sensor number ...............................
7-bit numeric reflecting the SEU Sensor port that the Sensor is plugged into.

*

Sensor button states.......................
2-bit states of any button switches integrated into the Sensor. A VIPER™
Stylus uses one of these bits.
Distortion level ...............................
8-bit numeric distortion level detected by the Sensor in levels 0-255.
Auxiliary digital input value ...........
10-bits of available data input for custom integrated hardware.

*

Sensor Position (X, Y, Z) .................
32-bit floating point Cartesian coordinates in position units configured by
the UNITS command.

*

Sensor Orientation .........................
Expressed as (3) or (4) 16-bit compressed values for Euler Angles (Azimuth,
Elevation, Roll) or a 4-term Orientation Quaternion Q(w, x, y, z)*, as
configured by the UNITS command.
[*Note order of Quaternion components: Scalar value w is output first.]*

Sensor Acceleration ........................
Expressed as (4) 16-bit compressed values for acceleration in X, Y, Z andmagnitude.

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Acceleration-mode P&O output is specified as an argument to the SINGLE PNO and CONTINUOUS PNO
commands.
In VIPER™ Command Manager, to specify
Acceleration-mode, selectMotion Menu→Acceleration Output Mode.
Subsequent Single- or Continous-P&O output willreflect this selection.

4.4.3 SINGLE PNO COMMAND
This command polls VIPER™ for a single frame of P&O data. VIPER™ emits a frame that includes P&O data fromall connected Sensors, as summarized above in Section 4.4.1 or an Acceleration-Mode P&O frame as summarized
in Section 4.4.2., depending on the P&O mode specified in the command arguments.
In VIPER™ Command Manager:
To collect a single frame of P&O data:
Click onin the toolbar,
orType the p keyboard shortcut anywhere on
the app window.
VIPER Command Manager displays aStandard- or Acceleration-Mode P&O frame
based on the Motion menu selection
described above.
Scope: SEU

4.4.4 CONTINUOUS PNO COMMAND
This command starts or stops Continuous P&O data stream from VIPER™. When the system is in continuous
mode, P&O frames are streamed continuously at the frame update rate specified by the FRAME RATE command.
P&O data from all connected Sensors is output, as summarized in Section 4.4.1 or an Acceleration-Mode P&O
frame as summarized in Section 4.4.2, depending on the P&O mode specified in the command arguments.
P&O frame count is reset to zero, left unchanged, or set to a custom value, depending on frame countspecification in the command arguments. (When continuous data is started via VIPER Command Manager, frame
count is always reset to zero.)

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USER MANUALIn VIPER™ Command Manager:
To start and stop continuous P&O data:
Click onin the toolbar,
orType the c keyboard shortcut anywhere on
the app window.
VIPER Command Manager displays
continuous Standard- or Acceleration-ModeP&O frames based on the Motion menu
selection described above.
Scope: SEU

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4.5 READ-ONLY COMMANDS
4.5.1 BIT RESULTS COMMAND
This command allows the user to read Built-In Test (BIT) results
This is a diagnostic command that allows the user to detect and determine the cause of VIPER™ internal systemerrors. If errors are detected a flag is placed in P&O output frame header. The BIT RESULTS command can beused to gather more information if this flag is output.
Details of BIT errors are described in Section 6.
In VIPER™ Command Manager, to display VIPER™
BIT RESULTS, selectDevice Menu→BIT Results

Scope: SEU, Get Only

4.5.2 STATION MAP COMMAND
The purpose of this command is to report the detected Sensors and Sources connected to the system.
In VIPER™ Command Manager detected Sensor and Source counts are included in the SEU Who Am I display. See
Section 4.5.4 below

4.5.3 DISTORTION MAP STATUS COMMAND
This command will return the name of the installed distortion map and can be used to erase it from VIPER™
memory.

Note: As of initial release, user-installed maps are not yet functional.

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4.5.4 WHO AM I COMMAND
This command returns basic identification and firmware version of VIPER™ system.
In VIPER™ Command Manager, to display VIPER™
Who Am I information, click on the VIPER™ SEU
icon
in the Status Pane.

Scope: SEU, Get Only

4.5.5 SENSOR WHO AM I COMMAND
This command retrieves the Sensor serial number.
In VIPER™ Command Manager, to display Sensor
Who Am I information, click a sensor iconinthe Status Pane.

Scope: Sensor, Get Only

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4.5.6 SOURCE WHO AM I COMMAND
This command retrieves a Source serial number.
In VIPER™ Command Manager, to display VIPER™
Who Am I information, click on the VIPER™ SEU
icon
in the Status Pane.
Then click on the Sources button.

Scope: Source, Get Only

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4.6 EXECUTIVE COMMANDS
4.6.1 PERSIST COMMAND
This command saves the current configuration settings to non-volatile FLASH. When VIPER™ reboots, the current
settings persist. Only configuration settings marked “Persistent” can be saved. To restore VIPER™ to Factory
Default Configuration, apply the BLOCK CONFIG RESET command prior to PERSIST.
In VIPER™ Command Manager, to persist current
VIPER™ settings, selectDevice Menu→Persist Current Configuration

Scope: SEU

4.6.2 BLOCK CONFIG RESET COMMAND
This command is used to RESET all VIPER™ configuration settings to Factory Defaults. To restore the VIPER™ to
Factory Configuration, follow the BLOCK CONFIG RESET command with PERSIST.
In VIPER™ Command Manager, to reset VIPER™ tofactory default configuration, selectDevice Menu→Reload Default ConfigurationorSelectin SEU Block Configuration panel
toolbar.

Scope: SEU
When executing BLOCK CONFIG RESET and PERSIST commands in VIPER™
Command Manager, a challenge window will appear, as these operations may not
be recoverable.

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4.6.3 ENABLE DISTORTION MAP COMMAND
This command will enable or disable a Distortion map if one is installed.

Note: As of initial release, user-installed maps are not yet functional.

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5. PRECAUTIONS
1.

2.

3.
4.
5.

Using the VIPER™ Tracker in the vicinity of conductive metals may lead to errors in the accuracy ofthis product. The errors are caused by eddy current distortion. VIPER™ contains eddy current
mitigation but there will still be some accuracy degradation in heavily distorted environments.
VIPER™ magnetic signals operate in a range of 10 kHz to 40 kHz. Operating in an environment ofsimilar magnetic signals will cause interference. If interference does exist, VIPER™ can operate inmultiple frequency bands to enable a user to attempt to operate in a band where there is nointerference.
Do not operate another VIPER™ Source within 7 meters of a same frequency Source as this could
cause interference.
Do not place Sensors in close range of un-configured Source(s) to avoid transient tracking
degradation. See warning note in Section 4.2.14.1 “SOURCE SELECT command.”See BIT ERRORS in Section 6.

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6. BIT ERRORSThis section explains the Built-In Test (BIT) error codes that the VIPER™ may return in response to the BIT
RESULTS command or in response to any other command if the tracker cannot operate with the reported error
condition.
Note: These error codes indicate a malfunction in VIPER™ system hardware or
firmware, or in a system component that may result in inaccurate measurements.

Code

Displayed Message

Definition00

No Error

System startup and self-test success.

01

SENSOR Error

A problem with a Sensor has been
detected.

Actions to Take Try a different Sensor to see if
the error is cleared.
 Contact Polhemus TechnicalSupport.

02

SENSOR PORT Error

A problem with an SEU Sensor PORT has
been detected.

 Move Sensor to a different port
to see if the error clears.
 Contact Polhemus TechnicalSupport.

03

SOURCE Error

A problem with a Source and/or SEU
Source PORT has been detected.

 Try a different Source.
 Try a different Source Port.
 Contact Polhemus TechnicalSupport.

04

SEU Error

A problem with SEU hardware or
firmware has been detected.

 Contact Polhemus TechnicalSupport.

05

Duplicate Source
Frequencies

Two or more Sources operating at thesame EM frequency are plugged into the
SEU.

 Unplug the duplicate frequency
Source(s).
 Replace with a Source of adifferent frequency.
 Power-cycle VIPER™ or Soft
Reset.

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7. EXPLANATION OF SYMBOLS

More Information

Helpful tip

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USER MANUALAPPENDIX A. TERMS & ACRONYMS
Alignment

Obtaining congruence between the axes of the VIPER™ system and the axes of theapplication. The process whereby the VIPER™ system coordinate reference is brought
into coincidence, either physically or mathematically, with other coordinates of theenvironment.

Alignment Frame

The reference frame in which the position and orientation of the Sensor is measured.
The default alignment frame is the Source frame.

API

Application Programming Interface. Programming library used to develop custom host
software for driving the instrument. Sometimes used interchangeably with “SDK.”ASCII

American national Standard Code for Information Interchange defines a certain 8-bit
code for display and control characters.

Attitude

See Orientation.

Attitude Matrix

A three-by-three matrix containing the direction cosines of the sensor’s X axis in column
one, the direction cosines of the sensor’s Y axis in column two, and the direction cosinesof the sensor’s Z axis in column three. The order of the Euler angle rotation sequence isazimuth, elevation, and roll.
X Direction Cosines

Y Direction Cosines

Z Direction Cosines

CA*CE

CA*SE*SR - SA*CR

CA*SE*CR + SA*SR

SA*CE

CA*CR + SA*SE*SR

SA*SE*CR – CA*SR

-SE

CE*SR

CE*CR

Where:CA = Cos (azimuth)
CE = Cos (elevation)
CR = Cos (roll)
SA = Sin (azimuth)
SE = Sin (elevation)
SR = Sin (roll)Auto-Hemisphere Tracking

With FT Sensor technology, VIPER™ is able to automatically detect and track theoperating Hemisphere of an FT Sensor.

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AzimuthThe coordinate of orientation tracking in the horizontal plane. Azimuth is a rotation
around the Z (vertical) axis, where an increase in the angle is clockwise when viewed in
the positive direction along this axis. Note, in Polhemus’ default frame of reference, the+Z axis points down, with +X pointing forward and +Y pointing to the right. The term“yaw” is often substituted for azimuth, especially in the context of flight.

Baud Rate

The signaling rate on a serial line. For example, to convey an 8-bit byte normallyrequires at least two additional bit times, a start bit and a stop bit so thatsynchronization is possible without a separate clocking line. For example, such anarrangement implies for a 115200 baud rate conveyance of data at a 115200*8/10 =92,160 bit rate.

Benign Environment

A tracking environment free of the need for special calibration or compensation broughton by the unique features of a particular installation and its environment (e.g. high lightlevels for optical tracking, high sound levels for sonic tracking, or high metallic distortion
for magnetic tracking). If not otherwise noted, all measurements and statements
pertaining to VIPER™ performance shall be regarded as occurring in such a benign
environment.

BIT

Built-In Test features in the VIPER™ system firmware monitor the status and health of
the VIPER™ system and flag certain preset conditions; not to be confused with “bit,” acontraction of “binary digit.”

Boresight

Any procedure that rotates the Sensor frame so as to precisely align the Sensor to thedesignated reference frame.
In a VIPER™ system context, the term usually refers to the system software routine that,on command, performs a coordinate rotation, which effectively aligns the Sensor frame
to a predefined boresight reference orientation, e.g. the Source reference frame.

Cartesian Coordinates

In three dimensions, three numbers that indicate the location of a point relative to a
fixed reference point (the origin), being the shortest (perpendicular) distances fromthree fixed and orthogonal axes which intersect at the origin.

DegreeA measurement of a plane angle, defined so that a full rotation is 360 degrees. A fullrotation equals 2π radians; therefore, one degree is equivalent to π/180 radians. See
also Radians and Orientation Angles.

Digitizer

A special Sensor, shaped like a pen or Stylus, used for recording the X, Y, Z coordinatesof an object; easily captures data points in hard to reach places; requires no mechanicalarm or optical markers.

Direction Cosines

The cosines of the angles between the Sensor’s x, y, z axes and the X, Y, Z axes of themeasurement reference (alignment) frame.

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Elevation

Coordinate of orientation tracking in the vertical plane where an increase in the angle isupward from the horizontal. Elevation is a rotation around the Y (horizontal) axis, where
an increase in the angle is clockwise when viewed in the positive direction along thisaxis. Note, in Polhemus’ default frame of reference, the +Y axis points to the right, with+X pointing forward and +Z pointing down. The term “pitch” is often substituted for
azimuth, especially in the context of flight.

EM Field

Electromagnetic Field. An EM field is a combination of an electric field (created bychanges in voltage) and a magnetic field (created by flow of electric current).

Euler Angles

See Orientation Angles.

Factory Defaults

The values assigned to certain system variables by the factory. Stored in non-volatilememory, they are used to reinitialize the variables if configuration information is lost.

FirmwareTerm used to describe the software programmed into VIPER™ non-volatile memory.

Frame of Reference

Also called a reference frame. In 3 dimensions, 3+1 reference points are sufficient tofully define a reference frame. Using Cartesian coordinates, a reference frame may be
defined with a reference point at the origin and a reference point at one unit distancealong each of the 3 coordinate axes. When a standard Polhemus Source serves as thereference, the origin is at the EM center of the Source and the positive X, Y, and Z axes
extend forward, right, and down from the EM center.

Hemisphere

The symmetry of the magnetic fields generated by the Source creates two mathematicalsolutions to each set of Sensor data processed. Therefore, only half of the total spatial
sphere surrounding the Source is practically used at any one time without ambiguity in
the X, Y, Z measurements (usually sign flips). This half sphere is referred to as the“current hemisphere.”
When configuring Hemisphere, the selected hemisphere is defined by a LOS (line-ofsight) vector from the source through a point at the zenith of the hemisphere, and isspecified by the direction cosines of the chosen LOS vector. See also Hemisphere
Tracking and Auto-Hemisphere Tracking definitions. See Appendix B.

Hemisphere Tracking

A feature in which the Polhemus tracker continuously modifies the operating
Hemisphere, allowing full tracking coverage around all sides of the Source. Note that the
Sensor must be in a known, valid Hemisphere before engaging Hemisphere Tracking.

Host

Any modern computer device capable of supporting an RS-422 interface or the highspeed USB 2.0 interface and capable of bi-directional data transmission.

I/O latency

The interval of time needed by the host computer to transfer data from the VIPER™
system into the host application.

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The interval of time between requesting a VIPER™ system data point and receiving it
into the host computer.

Latency

The interval of time between when measurement data were collected and when the
P&O result is ready for transfer to the host computer.

Local Source

The Source that is local to a given Sensor is determined by where the Source connector
is plugged into the SEU. The Local Source is the Source that is
detected in the Source Port at the same board level as the
Sensor. The green arrows in the diagram at right show thelocation of the local Source Port for each group of 4 sensors.
By default, Sensors report P&O with respect to the Local
Source or the Nearest Source detected on a lower numbered
Source Port if none is detected in the local Source port. See
also Nearest Source definition.

Motion Tracking Area

Also called the Motion Box or Tracking Volume. The volume in which motion tracking is
specified to perform as prescribed. Although this 3D volume usually is cubical in nature,
many of the tracking technologies known as ‘active’ are dependent on a source ofstimulation (e.g., magnetic field, light source) which actually performs equally well at aconstant radius from the Source so that the “box” actually might be better described asspherical or hemispherical.

Nearest Source

The Local Source, or if no Local Source is detected, then the first Source detected on alower numbered Source Port. The yellow arrows in the diagram at right show thelocation of the Nearest Source for the top two groups of 4
sensors. By default, Sensors report P&O with respect to the
Local Source or the Nearest Source detected on a lower
numbered Source Port if none is detected in the local Source
port. See also Local Source definition.

NIST-traceable

NIST traceable calibration is an assurance program that certifies that a manufacturer isfully equipped to calibrate equipment to National Institute of Standards and Technology(NIST) standards and that any products offered by that manufacturer will match those
NIST-maintained measurement standards. With NIST traceable calibration, Polhemus’
calibration fixturing has an unbroken chain of measurements that leads back to NIST
maintained standards.

Orientation

The imaginary rotation that is needed to move an object from a reference placement to
its current placement. Orientation is given relative to a frame of reference specified by aCartesian coordinate system. Also known as Attitude.

Orientation Angles

The azimuth, elevation, and roll angles that define the current orientation of the Sensor
coordinate frame with respect to the designated tracking system reference frame. Euler
angles may be specified in degrees or radians.

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USER MANUALThe Euler angle coordinates that are output by VIPER™ as
one measure of Sensor orientation are graphically defined in
the figure below. Here, the x, y, z and X, Y, Z tri-axis arrays
represent independent, three-dimensional orthogonal
coordinate frames. The x, y, z triad represents the Sensor
frame in its current orientation state. The X, Y, Z triad
represents the reference frame against which the relativeorientation of the Sensor frame is measured. By definition,
the X, Y, Z frame also represents the zero-orientationreference state of the Sensor frame.

LegendX, Y, Zx, y, zThe Euler angles azimuth, elevation and roll, are designated, , and . These angles represent an azimuth-primary
sequence of frame rotations that define the current
orientation of the Sensor with respect to its zero-orientation
state. The defining rotation sequence is an azimuth rotation
followed by an elevation rotation followed by a roll rotation.
= Alignment (Reference) Frame= Rotated Stylus or Sensor Coordinate= Azimuth= Elevation= RollThe azimuth angle  is defined in the figure as a rotation of
the X and Y reference axes about the Z reference axis. The
transition axes labeled X’ and Y’ represent the orientation of
the X and Y axes after the azimuth rotation.

The elevation angle  is defined as a rotation of the Zreference axis and the X’ transition axis about the Y’ transition axis. The transition axis
labeled Z’ represents the orientation of the Z reference axis after the elevation rotation.
The current x-axis of the current Sensor frame represents the orientation of the X’transition axis after the elevation rotation.
Last, the roll angle  is defined as a rotation of the Y’ and Z’ transition axes about the xaxis of the Sensor frame. The y and z-axes of the current Sensor frame represent theorientation of the Y’ and Z’ transition axes after the roll rotation.
In the diagram above, the azimuth, elevation and roll rotations are positive, negativeand positive respectively.

Output List

A list of the data items included in a data record.

ParityIn serial communication, a parity bit may be added to each transmitted byte to check
whether corruption has occurred. Serial port configuration may set parity to None,
Even, or Odd. During transmission, the sender calculates the parity bit and sends it. The
receiver calculates parity and compares the result to the parity bit received.

Persistent Setting

Tracker settings that may be stored in VIPER™ flash memory so that they will persist
through power-cycle or soft reset. (These settings are not automatically persisted,
however. A PERSIST operation must be performed to store the settings to flash.)

P&O

Acronym for position and orientation, the six pieces of data needed to fully describe
tracking of an object in 3D space. Some tracking devices, by virtue of their principle of

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operation, can produce only position or only orientation whereas others can produce both
P&O (although the user usually can opt for only those parameters desired).
PNO

See P&O.

Position

The (X, Y, Z) Cartesian coordinates of position tracking where normally +X is in the forward
direction; +Y is in the right hand direction; and +Z is downward.

Pitch

See Elevation.

Quaternion

Also called Orientation Quaternion or Attitude Quaternion. A four-parametermathematical notation for representing orientations and rotations of objects in three
dimensions. Compared to Euler angles they are simpler to compose and avoid the
problem of gimbal lock. Compared to rotation matrices they are more compact, more
numerically stable, and more efficient. Typically represented in the form q = q0 + iq1 +jq2 + kq3, a quaternion contains a vector and a scalar. In this form, q0 is the scalar partand (iq1 + jq2 + kq3) is the vector part. In Polhemus’ notation, quaternion parameters(q0-3) are sometimes referred to as (w, x, y, z). The quaternion can be used to represent
the Sensor’s orientation without the need for trigonometric functions. Note that
Polhemus trackers output quaternion with the scaler value w first, followed by thevector coords x, y, z.
The attitude matrix output from VIPER™ can be equivalently represented by thefollowing matrix using quaternions:
X Directional Cosines

 q2 + q2 - q2 - q2
1
2
3
 0

 2( q3 q0 + q1 q 2 )2( q1 q3 - q0 q 2 )Y Directional Cosines2( q1 q 2 - q0 q3 )
2

2

2

2

q0 - q 1 + q 2 - q 32( q1 q0 + q3 q 2 )Z Directional Cosines2( q1 q3 + q0 q 2 )
2( q 2 q3 - q0 q1 )

2
2
2
2
q0 - q1 - q 2 + q3 RadianThe SI (Système international) unit for measuring angles. An arc of a circle with the samelength as the radius of that circle subtends an angle of 1 radian. The circumference
subtends an angle of 2π radians. More generally, the magnitude in radians of thesubtended angle is expressed as θ = s/r, where s is the arc length and r is the radius. See
also Degree and Orientation Angles.

Reset Button

System reset switch; does not cycle power but does a soft-reboot of VIPER™ SEU.

Response

The interval of time between a request to the VIPER™ system to collect a data point andwhen that data is available for input from the VIPER™ system.

Roll

Coordinate of orientation tracking. Roll is a rotation around the X (horizontal
forward/aft) axis, where an increase in the angle is clockwise when viewed in thepositive direction along this axis. Note, in Polhemus’ default frame of reference, the +X
axis points forward, with +Y pointing to the right and +Z pointing down.

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SDK

Software Development Kit; software development toolset available for VIPER™-based
trackers, consisting of programming libraries, help files, and sample code. SDK is
sometimes referred to as “API,” although API refers specifically to the programming
libraries used to interface with the instrument.

SEU

System Electronics Unit. The main electronics unit of the tracking system to which
Sensors and Source may be connected.

SensorThe Sensor measures the magnetic field generated by the Source. The Sensor is used to
track both the position and orientation of the object to which it is attached, relative tothe measurement reference frame.

SourceThe Source generates the magnetic field measured by the Sensor. The Source’s X, Y, andZ-axes are the default measurement reference frame.

StylusA pencil-shaped housing for the Sensor with an integral switch used by the operator toindicate and/or select points to be digitized.

Sync

Shorthand for synchronization. For example, “sync signal.”

Units

The unit of assumed Position and Orientation. VIPER™ outputs Position data in inches,
feet, centimeters or meters. Orientation is output as Euler angles in degrees or radians,
or Quaternion.

Update Rate

The rate at which P&O data is output from the VIPER™ system. Usually expressed asframes per second (fps) or Hertz (Hz).

Useful Range

The operating distance (Sensor to Source) at which the resolution and noise performance of
the VIPER™ system can be realized.

User Defaults

The values assigned to certain system variables by the user. Stored in non-volatilememory, the system receives these variable values at power-up.

VPcmdMgr

VIPER™ Command Manager application.

XYZ or X, Y, Z

The Cartesian coordinates of position tracking where normally +X is in the forward
direction; +Y is in the right hand direction; and +Z is downward.

XYZAER

The output string of data reporting the position, XYZ, and orientation, AER – azimuth,
elevation and roll – of the tracking Sensor.

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YawPage 74 of 86

Same as azimuth.

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USER MANUALAPPENDIX B. SOURCE HEMISPHERES
If the application requires the Sensor(s) to move back and forth to different sides of
the Source, Hemisphere Tracking or Auto-Hemisphere must be enabled with the
HEMISPHERE command.
When the VIPER™ system is started, Sensors track by detecting the presence of the electromagnetic (EM)field produced by one or more Sources in the tracking area.
The field emitted by the Source is a symmetrical dipole field. That means that when it is detected fromany direction, the detected field is identical to the field emitted in the opposite direction. For that reason,
the VIPER™ Sensor cannot initially distinguish the direction from which it initially detects the Source; itneeds to be told at startup, using the HEMISPHERE command or via Auto-Hemisphere.
Source hemispheres are described by the Cartesian axes with origin at the center of the Source. Figure 22
below depicts the location of the +/- X, Y, Z sides of the standard Source.

FIGURE 22. SOURCE HEMISPHERES

Unless configured otherwise, VIPER™ assumes that all Sensors will detect the Source(s) from the +X direction.
That is, the Sensors are assumed to operate in the “plus X” hemisphere. The default hemisphere setting is +X
for all Sensors. It is for this reason that the Getting Started section advises the novice user to position the Sensor
on the +X side of the Source.
When the correct hemisphere is not established, the Sensors’ position coordinates output will frequently havethe wrong sign.
Incorrect hemisphere setting or operation is the number one cause of sign errors in
the position data.

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Once correct hemisphere is established, it is usually a good idea to enable Hemisphere Tracking. When
Hemisphere Tracking is enabled, VIPER™ automatically maintains correct hemisphere even if the Sensor is passed
to the opposite side of the Source.

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USER MANUALAPPENDIX C.

SENSOR AND SOURCE DIMENSIONSFIGURE 23. OUTLINE DIMENSIONS (APPROX.), VIPER™ FT-STANDARD SENSOR

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USER MANUALFIGURE 24. OUTLINE DIMENSIONS (APPROX.), VIPER™ FT-FLATSIDED SENSOR

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USER MANUALFIGURE 25. OUTLINE DIMENSIONS (APPROX.), VIPER™ FT-CLIP SENSOR

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USER MANUALFIGURE 26. OUTLINE DIMENSIONS (APPROX.), VIPER™ FT SENSOR CLIP

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USER MANUALFIGURE 27. OUTLINE DIMENSIONS (APPROX.), TX2 STANDARD SOURCE

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USER MANUALFIGURE 28. OUTLINE DIMENSIONS (APPROX.), TX4 SOURCE

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USER MANUALFIGURE 29. OUTLINE DIMENSIONS (APPROX.), VIPER™ HR SOURCE

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USER MANUALAPPENDIX D. LIMITED WARRANTY AND LIMITATION OF LIABILITY
Polhemus warrants that the Product shall be free from defects in material and workmanship for a period of two
years from the date of Polhemus’ delivery to the Buyer, or two years and 30 days from the date Polhemus
shipped Product to an authorized reseller, whichever occurs first, with the exception of all Sensors which have awarranty period of one year against material defects. Polhemus shall, upon notification within the warranty
period, correct such defects by repair or replacement with a like serviceable item at Polhemus' option. This
warranty shall be considered void if the Product is operated other than in accordance with the instructions in
Polhemus' User Manual or is damaged by accident or mishandling. Parts or material which are disposable or
expendable or subject to normal wear beyond usefulness within the warranty period such as lamps, fuses, etc.,
are not covered by this warranty.
In the event any Product or portion thereof is defective, Buyer shall promptly, and within the warranty period,
notify Polhemus in writing of the nature of the defect and return the defective parts to Polhemus at the directionof Polhemus’ Customer Service representative. Upon determination by Polhemus that the parts or Products are
defective and covered by the warranty set forth above, Polhemus, at its option shall repair or replace the same
without cost to Buyer. Buyer shall be responsible for any import/export duties/tariffs and pay all charges fortransportation and delivery costs to Polhemus' factory for defective parts where directed to be sent to Polhemus,
and Polhemus shall pay for transportation costs to Buyer's facility only for warranty replacement parts andProducts. Removed parts covered by claims under this warranty shall become the property of Polhemus.
In the event that allegedly defective parts are found not to be defective, or not covered by warranty, Buyer
agrees that Polhemus may invoice Buyer for all reasonable expenses incurred in inspecting, testing, repairing andreturning the Products and that Buyer will pay such costs on being invoiced therefor. Buyer shall bear the risk ofloss or damage during transit in all cases.
Any repaired or replaced part or Product shall be warranted for the remaining period of the original warranty or
thirty (30) days, whichever is longer.
Warranties shall not apply to any Products which have been:






repaired or altered other than by Polhemus, except when so authorized in writing by Polhemus; orused in an unauthorized or improper manner, or without following normal operating procedures; or
improperly maintained and where such activities, in Polhemus' sole judgment, have adversely affected theProducts. Neither shall warranties apply in the case of damage through accidents or acts of nature such as
flood, earthquake, lightning, tornado, typhoon, power surge(s) or failure(s), environmental extremes orother external causes. Warranties shall not apply to any Products if the Products are defective because of
normal wear and tear; orused for any purpose without obtaining any applicable regulatory approvals.

POLHEMUS DOES NOT WARRANT AND SPECIFICALLY DISCLAIMS THE WARRANTY OF MERCHANTABILITY OF THE
PRODUCTS OR THE WARRANTY OF FITNESS OF THE PRODUCTS FOR ANY PARTICULAR PURPOSE. POLHEMUS
MAKES NO WARRANTIES, EXPRESS OR IMPLIED, EXCEPT OF TITLE AND AGAINST PATENT INFRINGEMENT, OTHER
THAN THOSE SPECIFICALLY SET FORTH HEREIN.
IN NO EVENT SHALL POLHEMUS BE LIABLE UNDER ANY CIRCUMSTANCES FOR SPECIAL INCIDENTAL OR
CONSEQUENTIAL DAMAGES, INCLUDING, BUT NOT LIMITED TO LOSS OF PROFITS OR REVENUE. WITHOUT
LIMITING THE FOREGOING POLHEMUS'S MAXIMUM LIABILITY FOR DAMAGES FOR ANY CAUSE WHATSOEVER,
EXCLUSIVE OF CLAIMS FOR PATENT INFRINGEMENT AND REGARDLESS OF THE FORM OF THE ACTION(INCLUDING BUT NOT LIMITED TO CONTRACT NEGLIGENCE OR STRICT LIABILITY) SHALL BE LIMITED TO BUYER'SACTUAL DIRECT DAMAGES, NOT TO EXCEED THE PRICE OF THE GOODS UPON WHICH SUCH LIABILITY IS BASED.

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USER MANUALAPPENDIX E.

CUSTOMER SERVICE

If problems are encountered with the VIPER™ or if you are having difficulty understanding how the commands
work, help is just a telephone call away.
Call Polhemus at the numbers listed below and select “2” for Customer Service and then “1” for TechnicalSupport. Polhemus is open Monday through Friday, 8:00 AM to 5:00 PM, Eastern Standard Time (US). For themost part, our customer service representatives are usually able to solve problems over the telephone and get
you back into the fast lane right away.
Help is also available on our web page at https://polhemus.com/support/technical-support/. Selecttechsupport@polhemus.com to send us an email describing the problem or question.
If a problem requires repair of your system, the customer service representative will issue a Return Merchandise
Authorization (RMA) number and you may then return the system to the factory. Do not return any equipment
without first obtaining an RMA number. Please retain and use the original shipping container, if possible, toavoid transportation damages (for which you or your shipper would be liable). If your system is still underwarranty, Polhemus will repair it free of charge according to the provisions of the warranty as stated in Appendix
D of this document. The proper return address is:Polhemus RRL : RMA #_______
40 Hercules Drive
PO Box 560
Colchester, VT 05446-0560
USA
From within the U.S. and Canada: (800) 357-4777
From outside the U.S. or Canada: (802) 655-3159

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