Xsens MTi Series User manual

Xsens Technologies B.V.
Xsens North America, Inc.
Pantheon 6a
P.O. Box 559
7500 AN Enschede
The Netherlands
phone [phone]
fax [phone]
e-mail [e-mail]
internet www.xsens.com
101 N, Pacific Coast Hwy
Suite 101
El Segundo, CA 90245
USA
phone [phone]
fax [phone]
e-mail [e-mail]
internet www.xsens.com
Document MT1600P, Revision 2019.A, 29 Aug 2019
General information for MTi series
MTi Family Reference Manual

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Revisions
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© 2005-2019, Xsens Technologies B.V. All rights reserved. Information in this document is subject to
change without notice. Xsens, MVN, MotionGrid, MTi, MTx and Awinda are registered trademarks or
trademarks of Xsens Technologies B.V. and/or its parent, subsidiaries and/or affiliates in The
Netherlands, the USA and/or other countries. All other trademarks are the property of their respective
owners.

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Table of Contents
1XSENS CUSTOMER SUPPORT AND BASE................................................................................ 6
2INTRODUCTION ............................................................................................................................ 7
2.1 FROM IMU TO GNSS/INS ............................................................................................................ 8
2.1.1 IMU .................................................................................................................................... 8
2.1.2 VRU ................................................................................................................................... 8
2.1.3 AHRS ................................................................................................................................. 8
2.1.4 GNSS/INS.......................................................................................................................... 8
2.2 XSENS MTI HARDWARE PLATFORMS .............................................................................................. 9
2.2.1 MTi 1-series ....................................................................................................................... 9
2.2.2 MTi 600-series ................................................................................................................... 9
2.2.3 MTi 10-series ..................................................................................................................... 9
2.2.4 MTi 100-series ................................................................................................................... 9
3GETTING STARTED WITH THE MTI .......................................................................................... 11
3.1 OVERVIEW MTI DEVELOPMENT KIT.............................................................................................. 11
3.1.2 MT Software Development Kit (MT SDK)........................................................................ 13
3.1.3 Low-level Communication................................................................................................ 13
3.1.4Terms of use of MT Software Suite ................................................................................. 13
4MTI SYSTEM OVERVIEW ........................................................................................................... 15
4.1 TEST AND CALIBRATION .............................................................................................................. 15
4.2 COORDINATE SYSTEMS ............................................................................................................... 15
4.2.1 Calibrated inertial data and magnetic field data .............................................................. 15
4.2.2 Orientation increment and Velocity increment (dq and dv) ............................................. 16
4.2.3 Orientation data ............................................................................................................... 17
4.2.4 Velocity data .................................................................................................................... 18
4.2.5 Position data .................................................................................................................... 19
4.3 PHYSICAL SENSOR MODEL........................................................................................................... 19
4.3.1 Calibrated ∆q and ∆v outputs .......................................................................................... 20
4.3.2 Calibrated inertial and magnetic data outputs ................................................................. 20
4.3.3 High-rate (HR) inertial data outputs ................................................................................. 20
4.3.4 Free acceleration ............................................................................................................. 21
4.4 XSENS SENSOR FUSION ALGORITHMS ......................................................................................... 22
4.4.1 Internal Sensor Bias Estimation....................................................................................... 22
4.4.2 Roll and Pitch estimation ................................................................................................. 22
4.4.3 Heading/yaw estimation................................................................................................... 23
4.4.4 Velocity and Position estimation ...................................................................................... 23
4.4.5 Initialization ...................................................................................................................... 24
4.4.6 Filter Profile options ......................................................................................................... 24
4.4.7 Additional setting options and features............................................................................ 24
4.5 MTI SERIES INTERFACE OPTIONS ................................................................................................. 26
4.6 TIMING AND SYNCHRONIZATION ................................................................................................... 26
5INPUT AND OUTPUT SPECIFICATION...................................................................................... 27
5.1 OVERVIEW OF DATA OUTPUT PROTOCOLS .................................................................................... 27
5.2 OVERVIEW OF DATA INPUTS......................................................................................................... 27
5.3 BUILT-IN SELF-TEST .................................................................................................................... 27
5.4 TIMESTAMP AND PACKET COUNTER OUTPUT ................................................................................. 27
5.5 STATUS WORD ............................................................................................................................ 28

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6INSTALLATION TIPS AND TRICKS ........................................................................................... 29
6.1TRANSIENT ACCELERATIONS........................................................................................................ 29
6.2 VIBRATIONS................................................................................................................................ 29
6.3 MAGNETIC MATERIALS AND MAGNETS........................................................................................... 29
7WARRANTY AND LIABILITY...................................................................................................... 31
7.1 CUSTOMER SUPPORT ................................................................................................................. 31

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List of Figures
Figure 1: From IMU to GNSS/INS ........................................................................................................... 8
Figure 2: MTi 1-series.............................................................................................................................. 9
Figure 3: MTi 600-series.......................................................................................................................... 9
Figure 4: MTi 10-series............................................................................................................................ 9
Figure 5: MTi 100-series.......................................................................................................................... 9
Figure 6: MTi Development Kit .............................................................................................................. 11
Figure 7: Default coordinate system of MTi 1-series............................................................................. 16
Figure 8: Default coordinate system of MTi 600-series......................................................................... 16
Figure 9: Right hand rule ....................................................................................................................... 17
List of Tables
Table 1: MTi product documentation overview........................................................................................ 7
Table 2: Xsens MTi portfolio overview. ................................................................................................. 10
Table 3 Description of hardware components of Development Kit ....................................................... 11
Table 4 Description of software components of Development Kit......................................................... 12
Table 5: Conditions for the use of the MT Software Suite..................................................................... 13
Table 6: Data outputs with reference coordinate systems .................................................................... 16
Table 7: Yaw in different coordinate systems (applies only to VRU/AHRS and GNSS/INS product types).
The MTi is assumed to be mounted with its roll-axis (X) aligned with the roll-axis of the vehicle (front of
the vehicle). ........................................................................................................................................... 18
Table 8: Output specifications ∆q and ∆v outputs ................................................................................. 20
Table 9: Output specifications inertial and magnetometer data outputs ............................................... 20
Table 10: Output specifications high rate calibrated inertial data outputs............................................. 20
Table 11: Supplementary features and settings.................................................................................... 24
Table 12: overview of interface options in MTi portfolio ........................................................................ 26

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1 Xsens Customer Support and BASE
BASE by Xsens is an online support platform with a knowledge base and community forum on 3D motion
tracking technology and products. This enables faster and easier system integration by offering a large
source of high-quality technical information.
Knowledge base (FAQ)
The knowledge base provides articles written by Xsens Field Application Engineers and Product
Specialists. Topics discussed are best practices, tips and tricks for the use of Xsens’ products and inside
information about installation, MEMS sensors and GNSS receivers, hardware design, CAD-files, system
architecture, low-level communication and sensor fusion algorithms.
Community forum
The community forum is an online forum that gives direct access to Xsens’ engineers and other Xsens
users. As users may have faced similar challenges, the answer may already be on the forum.
The knowledge base and user community are searchable simultaneously. A search query thus shows
results irrespective of the source.
Please visit https://base.xsens.com to complete your 1-minute registration.
Additionally, tutorial videos on products, features and releases are available on BASE by Xsens via:
https://tutorial.xsens.com/.

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2 Introduction
This manual gives an overview of the latest generation Xsens products (MTi 1-series and MTi 600-
series) and their usage. For previous generations, refer to MTi User Manual
1
. The MTi product portfolio
from Xsens currently has family members ranging in functionality from Inertial Measurement Units
(IMU’s), Vertical Reference Unit (VRU), Attitude and Heading Reference System (AHRS) to a fully
integrated GNSS/INS (Global Navigation Satellite System/Inertial Navigation System). All products
contain a 3D IMU composed by a gyroscope and an accelerometer plus a 3D magnetometer, with
optionally a barometer and GNSS receiver.
The MTi product range is divided in several series, the MTi 1-series, the MTi 600-series, the MTi 10-
series and the MTi 100-series.
The MTi 1-series is a low-cost Surface-Mount Devices (SMD) module.
The MTi 600-series is a cost effective product line for easy integration.
The MTi 10-series
2
is Xsens’ entry level model with robust accuracy.
The MTi 100-series is a Xsens’ proven high end class of MEMS IMU’s, orientation and position sensor
modules.
Table 1 summarizes all available official documents for the Xsens MTi product line. It is highly
recommended to review all documents applicable to your Xsens Motion Tracker.
Table 1: MTi product documentation overview1
MTi 1-series
MTi 600-series
MTi 10/100-series
MTi Family Reference Manual
MTi User Manual
MTi 1-series Datasheet
MTi 600-series Datasheet
MTi 1-series DK User Manual
MTi 600-series DK User Manual
MTi 1-series HW Integration Manual
MTi 600-series HW Integration Manual
MT CAN Protocol Documentation
MT Manager Manual
Magnetic Calibration Manual
MT Low Level Communication Protocol Documentation
Firmware Updater User Manual
1
Links to the latest available documentation can be found via the following link: Xsens MTi Documentation
2
not recommended for new designs

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2.1 From IMU to GNSS/INS
Within each MTi series, Xsens offers several product variants. Each variant is based on a firmware
version which enables different functionalities. Figure 1 summarizes the functionality of each variant.
Figure 1: From IMU to GNSS/INS
2.1.1 IMU
The IMU variant is an Inertial Measurement Unit that measures 3D acceleration and 3D rate of turn with
the addition of 3D magnetic field data and, depending on the product, barometric pressure. It does not
fuse sensor data to deliver orientation estimates. The IMU can also be configured to output data
generated by the strapdown integration algorithm (orientation increments ∆q and velocity increments
∆v).
2.1.2 VRU
The Vertical Reference Unit (VRU) adds the first layer of algorithms which uses gravity as a reference
for roll and pitch calculations. Essentially it delivers the same data as the AHRS, except for the yaw.
The yaw estimate of a VRU product is unreferenced, which means that it is computed without any
geographic/magnetic reference, though still superior to just gyroscope integration (e.g., when using the
gyro bias estimation techniques). All data outputs from the IMU are also available in this product version.
The AHS feature is also available in this product variant (see also chapter 4.4.7)
2.1.3 AHRS
This is the full Attitude and Heading Reference System (AHRS). It gives various outputs: roll, pitch and
heading (true magnetic North referenced yaw). In addition, all functionality of the IMU and VRU are also
available in this product variant.
2.1.4 GNSS/INS
The GNSS/INS variant is a product with an interface to an external or internal GNSS receiver as well as
a barometer. It provides roll, pitch, yaw/heading, as well as 3D position, 3D velocity and time data. In
addition, all data outputs of the IMU, VRU and AHRS are also available in this product variant.

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2.2 Xsens MTi hardware platforms
This section summarizes all available Xsens MTi platforms (see Table 2).
2.2.1 MTi 1-series
The MTi 1-series is the Xsens’ smallest (12.1mm x 12.1mm), lightest (<1gr)
and most cost effective product suitable for SMD (Surface Mountable
Device) integration. It is compatible with the JEDEC PLCC-28 standard
footprint. Designed for integration in high volume applications.
Available in IMU, VRU, AHRS and GNSS/INS (with external GNSS
receiver) product versions.
Please refer to the MTi 1-series Datasheet for more information.
2.2.2 MTi 600-series
The MTi 600-series product line is designed to be lightweight, cost effective
and easy to integrate. It can be integrated in two ways: either with the
header facing downwards, directly mounted on a PCB, or standalone, using
a flat cable for communication. Additionally it features a CANbus interface.
Available in IMU, VRU, AHRS and GNSS/INS (with external GNSS
receiver) product versions.
Please refer to the MTi 600-series Datasheet for more information.
2.2.3 MTi 10-series
The MTi 10-series offers inertial and orientation data at an affordable price.
It features a sturdy anodized aluminium housing, and robust push/pull
connectors. The MTi-10 series can easily be recognized by the aluminium
silver base plate.
Available in IMU, VRU and AHRS product versions.
Please refer to the MTi User Manual for more information. This product is
not recommended for new designs.
2.2.4 MTi 100-series
The MTi-100 series is the high-performance product range of the MTi
product portfolio, with accuracies surpassing conventional MEMS motion
trackers, because of the use of superior gyroscopes and a new optimization
filter, going beyond standard Extended Kalman Filter implementations. In
addition, the factory calibration is more accurate, repeatable and robust.
The MTi 100-series can be recognized by the dark-grey/black base plate
and the small barometer holes on one side of the casing. The MTi-G-710
has an extra SMA connector to allow a GNSS antenna to be attached.
Available in IMU, VRU, AHRS and GNSS/INS (with internal GNSS receiver)
product versions.
Please refer to the MTi User Manual for more information.
Figure 2: MTi 1-series
Figure 3: MTi 600-series
Figure 4: MTi 10-series
Figure 5: MTi 100-series
including the MTi-G-710

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Table 2: Xsens MTi portfolio overview.
MTi 1-series
MTi 600-series
MTi 10-series
MTi 100-series
IMU
MTi-1 IMU
MTi-610 IMU
MTi-10 IMU
MTi-100 IMU
VRU
MTi-2 VRU
MTi-620 VRU
MTi-20 VRU
MTi-200 VRU
AHRS
MTi-3 AHRS
MTi-630 AHRS
MTi-30 AHRS
MTi-300 AHRS
GNSS/INS
MTi-7 GNSS/INS
MTi-670 GNSS/INS
-
MTi-G-710 GNSS/INS
This document focusses mainly on the MTi 1-series and MTI 600-series. For more information on the
MTi 10-series and MTi 100-series, please refer to the MTi User Manual.

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3 Getting Started with the MTi
3.1 Overview MTi Development Kit
The MTi development kit is a very easy to use starter’s kit that allows for fast and easy integration of the
MTi in any user scenario. Figure 6 shows a typical Development Kit, containing an MTi. All software and
installation instructions are available online via http://www.xsens.com/setup.
Figure 6: MTi Development Kit
Depending on the model of MTi you have purchased, the Development Kit can contain any of the
following items:
Table 3 Description of hardware components of Development Kit
Component
Description
An MTi Motion Tracker
Development board
A tool for prototyping and validation
(micro) USB (converter) cable
A cable to connect the MTi device to a USB port
multi-purpose (flat) cable
A cable which exposes all physical lines to a MTi device
GNSS daughter card
An accessory which fits the MTi 1-series and MTi 600-series
development board which contains a GNSS receiver (click-
boardTM compatible)
GNSS antenna
Test and Calibration certificate

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Table 4 Description of software components of Development Kit
Component
Description
MT Software Suite (MTSS)
available for download via http://www.xsens.com/setup
Xsens MTi USB driver
Part of the MTSS
MT Manager for Linux and
Windows
Part of the MTSS
MT Software Development Kit (MT
SDK) for multiple OS
Part of the MTSS, containing the following components:
•XDA public source files (C, C++ wrapper ; any OS)
•Example source code and examples
oC++
oC#
oPython
oMATLAB
oRobotic Operating System (ROS)
oEmbedded examples (ST Nucleo)
Magnetic Field Mapper –MFM
(Windows and Linux)
Part of the MTSS, containing the following component:
•MFM SDK (Windows and Linux)
Firmware Updater
Separate component design to update MTi device firmware
Documentation
Part of the MTSS, PDFs are available online, containing the
following components:
•Links to online manuals
•Xsens Device API library
MFM SDK Library
Library for the Magnetic Field Mapper
3.1.1 Getting Started with MT Manager software
The easiest way to get started with your MTi is to use MT Manager. MT Manager is a software tool to
easy get to know and to demonstrate the capabilities of the MTi and to configure the device to suit your
needs.
Additionally MT Manager allows you to:
•record data and playback/review data;
•view orientation, position and velocity in real-time;
•view inertial and magnetic sensor data in real time;
•view low-level communication and XDA communication via message terminals;
•export log files to ASCII and KMZ (format viewable in Google Earth);
•change and/or view various device settings and properties;
•reprocess recorded data with different settings.
NOTE: the most recent version of the software, source code and documentation can always be
downloaded on www.xsens.com/mt-software-suite. Links to documentation can be found on BASE:
http://xsens.com/xsens-mti-documentation
The latest firmware and firmware updater can be found here: https://www.xsens.com/mt-firmware/

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Please refer to the MT Manager User Manual
3
for more information on MT Manager.
3.1.2 MT Software Development Kit (MT SDK)
The Xsens Device API (XDA) serves as a starting point for system integrators interested in assessing
the basics of the SDK. The main objective of the SDK is to facilitate the development of user-specific
host applications based on Xsens motion trackers.
The MT Software Development Kit (MT SDK), part of the MT Software Suite installation, provides
examples based on XDA for multiple programming languages. These programming examples can be
used as a starting point for further software development.
The MT SDK 2019.x (and the MT Software Suite) is designed for the MTi 1-series, MTi 600-series, MTi
10-series and MTi 100-series. Links to the latest available documentation can be found via the following
link: Xsens MTi Documentation
See also: Introduction to the MT SDK programming examples for MTi devices
3.1.3 Low-level Communication
The low-level communication protocol (named Xbus protocol) offers full control and functionality. It is
essential on platforms that do not support the Xsens Device API, such as custom embedded computers
and microcontrollers.
The low-level communication is extensively described in the MT Low-Level Communication Protocol
Documentation3. Next to that, source code is delivered to make driver development and Xbus message
parsing for the MTi as easy and quick as possible.
3.1.4 Terms of use of MT Software Suite
The installer of the MT Software Suite can install 4 components: MT Manager, MT SDK, Magnetic Field
Mapper (MFM) and MFM SDK. The Firmware Updater is a separate installer. The MT Software Suite
has a Restricted License Agreement that you need to accept. In Table 5, the conditions for use of each
component are summarized.
Table 5: Conditions for the use of the MT Software Suite
Component
Conditions
MT Manager
For use with Xsens products only
Not allowed to re-distribute
Not allowed to reverse engineer
Not allowed to modify
MT SDK
For use with Xsens products only
Allowed to re-distribute “as is” or embed in programs
Not allowed to reverse engineer
Allowed to execute, reproduce, modify and compile (modified) source
code to use with Xsens products only
Not allowed to modify DLL
Include License Agreement with distribution
MFM
For use with Xsens products only
Allowed to re-distribute “as is”
Not allowed to reverse engineer
Not allowed to modify
Include License Agreement with distribution
3
Links to the latest available documentation can be found via the following link: Xsens MTi Documentation

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MFM SDK
For use with Xsens products only
Allowed to re-distribute “as is” or embed in programs
Not allowed to reverse engineer
Allowed to execute, reproduce, modify and compile (modified) source
code to use with Xsens products only
Not allowed to modify DLL
Include License Agreement with distribution
FWU
For use with Xsens products only
Allowed to re-distribute “as is”
Not allowed to reverse engineer
Not allowed to modify
Include License Agreement with distribution

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4 MTi System Overview
4.1 Test and Calibration
A correct calibration of the sensor components inside the MTi is essential for an accurate output. The
quality and importance of the calibration are of highest priority. Each Xsens’ MTi is calibrated and tested
by subjecting each device to a wide range of motions and temperatures.
The individual calibration parameters are used to convert the sensor component readout (digitized
voltages) to physical quantities as accurately as possible, compensating for a wide range of deterministic
errors. Additionally, the calibration values are used in Xsens sensor fusion algorithms, as discussed
later in this document.
Each MTi contains individual test and calibration data in its eMTS (electronic Motion Tracker Settings).
It is digitally signed by a Test Person and states the calibration values determined during the calibration
of the MTi at Xsens’ calibration facilities. The values can be seen by connecting the MTi to MT Manager
and navigating to Device Settings →Modelling Parameters.
Next to the calibration values shown in MT Manager, each device is calibrated according to more
complicated models to ensure accuracy (e.g. non-linear temperature effect, cross coupling between
acceleration and angular rate
4
).
4.2 Coordinate systems
Data from the MTi is represented in various coordinate systems, which are explained below.
4.2.1 Calibrated inertial data and magnetic field data
The default sensor-fixed frame (Sxyz) is a right-handed Cartesian coordinate system that is fixed to the
device. When the sensor is rigidly attached to another object or vehicle but not aligned, it may be
convenient to rotate the sensor coordinate system Sxyz to an object coordinate system (Oxyz).
Refer to BASE by Xsens - MTi reference co-ordinate systems for more information on the available
orientation resets.
Sxyz or Oxyz are the coordinate frames used to express the rate of turn, acceleration and magnetic field
outputs. The encased version of the MTi shows Sxyz on the sticker. Figure 8 and Figure 7 depict the
sensor coordinate system on the MTi 600-series and MTi 1-series. Later in this document, small x, y
and z are the axes labels for Sxyz and Oxyz. Capital X, Y and Z stand for the local-earth fixed coordinate
system (LXYZ).
4
Also known as “g-sensitivity”.

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The housing and PCB of the MTi 600-series are carefully aligned with the output coordinate system
during the individual factory calibration. The non-orthogonality between the axes of Sxyz is <0.05. This
also means that the output of 3D linear acceleration, 3D rate of turn and 3D magnetic field data all will
have orthogonal xyz readings within <0.05.
Some of the commonly used data outputs and their reference coordinate systems are listed in Table 6.
Table 6: Data outputs with reference coordinate systems
Data
Reference coordinate system
Acceleration
Sensor-fixed frame (Sxyz) or Oxyz
Rate of turn
Sensor-fixed frame (Sxyz) or Oxyz
Magnetic field
Sensor-fixed frame (Sxyz) or Oxyz
Velocity increment
Sensor-fixed frame (Sxyz) or Oxyz
Orientation increment
Sensor-fixed frame (Sxyz) or Oxyz
Free acceleration
Local earth-fixed frame (LXYZ), default ENU
Orientation
Local earth-fixed frame (LXYZ), default ENU
Velocity
Local earth-fixed frame (LXYZ), default ENU
Position
Local earth-fixed frame (LXYZ), default ENU
4.2.2 Orientation increment and Velocity increment (dq and dv)
The Strap Down Integration (SDI) output of the MTi contain orientation increments (dq) and velocity
increments (dv). These values represent the orientation change and velocity change during a certain
interval based on the output rate. The output rate is selectable up to 100 Hz or 400 Hz depending on
the product. The dq and dv values are always represented in the same coordinate system as calibrated
inertial data and magnetic field data, which can be Sxyz or Oxyz.
Figure 8: Default coordinate system of MTi 600-series
Z
X
Y
Figure 7: Default coordinate system of MTi 1-series
Z
X

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4.2.3 Orientation data
By default, the local earth-fixed reference coordinate system LXYZ is defined as a right-handed Cartesian
coordinate system with
5
:
•X positive to the East (E).
•Y positive to the North (N).
•Z positive when pointing up (U).
This coordinate system is known as ENU (East-North-Up) and is the standard in inertial navigation for
aviation and geodetic applications. Note that it is possible to change LXYZ using a different convention,
like NWU (North-West-Up) or NED (North-East-Down), by changing an alignment matrix or applying an
orientation reset.
The 3D orientation output is defined as the orientation between the body-fixed coordinate system, Sxyz
or Oxyz, and the local earth-fixed co-ordinate system, LXYZ.
Orientation output modes
The output orientation can be presented in different equivalent representations:
•Unit Quaternions;
•Euler angles
6
: roll, pitch, yaw (XYZ Earth fixed type) are output following the aerospace
sequence (Z-Y’-X”);
•Rotation Matrix (directional cosine matrix).
A positive rotation is always “right-handed”, i.e. defined according to the right-hand rule (corkscrew rule),
see Figure 9. This means a positive rotation is defined as clockwise in the direction of the axis of rotation.
Figure 9: Right hand rule
Refer to BASE by Xsens to find more information on how quaternions, Euler angles and the rotation
matrix relate to each other.
5
The default reference coordinate system LXYZ only applies to the MTi in Normal output mode. Refer to the Low
Level Communication Protocol Documentation for detailed orientation output specifications when using the ASCII
(NMEA) output mode.
6
Please note that due to the definition of Euler angles there is a mathematical singularity when the sensor-fixed x-
axis is pointing up or down in the earth-fixed reference frame (i.e. pitch approaches ±90). In practice, this means
roll and pitch is not defined as such when pitch is close to ±90 deg. This singularity is in no way present in the
quaternion or rotation matrix output mode.

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Interpretation of yaw as heading
Heading is defined as the angle between the north direction and the horizontal projection of the roll axis.
Heading is positive about the local vertical axis following the right-hand rule
7
.
With the default ENU LXYZ coordinate system, Xsens yaw output is defined as the angle between East
(X) and the horizontal projection of the sensor roll axis (x), positive about the local vertical axis (Z)
following the right-hand rule. Table 7 shows the different yaw values corresponding to the different local
coordinate systems that are available for the MTi.
Table 7: Yaw in different coordinate systems (applies only to VRU/AHRS and GNSS/INS product types). The
MTi is assumed to be mounted with its roll-axis (X) aligned with the roll-axis of the vehicle (front of the
vehicle).
Local coordinate
system (output)
Roll-axis of the vehicle
Yaw value
East-North-Up (ENU)
Pointing North
90 deg
East-North-Up (ENU)
Pointing East
0 deg
North-West-Up (NWU)
Pointing North
0 deg
North-East-Down (NED)
Pointing North
0 deg
When using the ENU convention (default), the yaw output is 0º when the vehicle (x-axis of the MTi) is
pointing East (X axis of LXYZ). When it is required that the yaw output is 0º when the x-axis of the MTi is
pointing North, it is recommended to select NWU or NED as the local coordinate system. In section 0
the various alignment resets are described.
When using the INS/GNSS products in an automotive application, as a best practice pay proper attention
to mounting of the MTi on the automotive platform/vehicle. It is recommended to always mount the MTi
with the x-axis pointing to the front of the vehicle irrespective of the local coordinate frame used for the
output data.
True North vs. Magnetic North
As defined above, the output coordinate system of the MTi is with respect to local Magnetic North. The
deviation between Magnetic North and True North (known as the magnetic declination) varies depending
on the location on earth and can be roughly obtained from the latest World Magnetic Model
8
of the
earth’s magnetic field as a function of latitude and longitude. The MTi accepts a setting of the declination
value. This is done by setting the position in the MT Manager, SDK or by Low level communication. The
yaw/heading will then be corrected for the declination calculated internally and thus referenced to “local”
True North. The GNSS/INS products set automatically the current position when a GNSS-position fix is
available, therefore the user does not have to insert it.
4.2.4 Velocity data
Velocity data, calculated by the sensor fusion algorithm is provided in the same coordinate system as
the orientation data (LXYZ), and thus adopts orientation resets as well (if any is applied). The velocity
output is available in all GNSS/INS products (MTi-G-710, MTi-7 and MTi-670).
Note that the velocity data coming directly from the PVT (Position Velocity Time) data retrieved from any
GNSS receiver provided with any Xsens development kit is represented in the NED reference frame.
Different GNSS receivers may represent the velocity in different coordinate frames.
7
IEEE Std 1559TM-2009: IEEE Standard for Inertial Systems Terminology
8
Xsens releases a firmware update when a new WMM version is available

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4.2.5 Position data
Position data, calculated by the sensor fusion algorithm is represented in Latitude, Longitude and
Altitude as in the WGS84 datum. The position output is available in all GNSS/INS products (MTi-G-710,
MTi-7 and MTi-670).
It is possible to retrieve position data calculated by the sensor fusion algorithm in Earth Centered –Earth
Fixed (ECEF) format. See MT Low Level Communication Protocol Documentation for more information.
4.3 Physical sensor model
This section explains the basics of the individual calibration parameters of each MTi.
The physical sensors inside the MTi (accelerometers, gyroscopes and magnetometers)
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are all
calibrated according to a physical model of the response of the sensors to various physical quantities,
e.g. temperature. The basic model is linear and according to the following relation:

󰇛󰇜
During factory calibration, to each MTi has been assigned a unique gain matrix, KTand the bias vector,
bT. This calibration data is used to relate the sampled digital voltages, u, from the sensors to the
respective physical quantity, s.
The gain matrix is split into a misalignment matrix, A, and a gain matrix, G. The misalignment specifies
the directions of the sensitive axes with respect to the ribs of the sensor-fixed coordinate system (Sxyz)
housing. E.g. the first accelerometer misalignment matrix element a1,x describes the sensitive direction
of the accelerometer on channel one. The three sensitive directions are used to form the misalignment
matrix:
  
  
  
 
 
  
 
 
    
  
  
With Orepresenting higher order models, temperature modelling, g-sensitivity corrections, etc.
Each individual MTi is modeled for temperature dependence of both gain and bias for all sensors and
other effects. This modeling is not represented by the simple model in the above equations but is
implemented in the firmware with the temperature coefficient being determined individually for each MTi
device during the calibration process. The basic indicative parameters in the above model of your
individual MTi can be found in MT Manager (Device Settings dialog).
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The barometer and GNSS receiver do not require additional calibration.

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4.3.1 Calibrated ∆q and ∆v outputs
The calibrated ∆q (delta_q) and ∆v (delta_v) outputs are the coning and sculling compensated
strapdown integrated data in the sensor-fixed coordinate system (Sxyz) or (Oxyz). Note that the value of
the output depends on the output frequency, as the values are integrated over the sample time. Delta_q
can also be noted as dq, delta_angle, del_q or OriInc. Delta_v can also be noted as dv, delta_velocity,
del_v or VelInc.
Table 8: Output specifications ∆q and ∆v outputs
Output
Unit
Delta_q (DataID 0x8030)
a.u. (quaternion values)
Delta_v (DataID 0x4010)
m/s
It is possible to multiply consecutive delta_q values to find the total orientation change over a specific
period. Note that this data is not drift free, it still contains the sensor bias, as it has not been processed
by the sensor fusion algorithm. Use the orientation output for drift free orientation.
4.3.2 Calibrated inertial and magnetic data outputs
Output of calibrated 3D linear acceleration, 3D rate of turn and 3D magnetic field data is in sensor-fixed
coordinate system (Sxyz) or (Oxyz). The units of the calibrated data output are as shown in Table 9.
Table 9: Output specifications inertial and magnetometer data outputs
Vector
Unit
Acceleration (DataID 0x4020)
m/s2
Angular velocity (RateOfTurn) (DataID 0x8020)
rad/s
Magnetic field (DataID 0xC020)
a.u. (arbitrary units; normalized to earth field
strength at the location the MFM is performed)
4.3.3 High-rate (HR) inertial data outputs
High-rate calibrated 3D acceleration (accelerometer) and 3D rate of turn (gyroscope) are outputted in
sensor-fixed coordinate system (Sxyz) or (Oxyz). The units of the calibrated data output are as shown in
Table 10. HR calibrated data is available at a higher rate than regular calibrated inertial data outputs. It
is outputted as a separate data packet next to the other data outputs. The maximum output rate, degree
of signal processing, and calibration applied depends on device type.
Refer to MT Low Level Communication Protocol Documentation
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for more details.
Table 10: Output specifications high rate calibrated inertial data outputs
Vector
Unit
AccelerationHR (DataID 0x4040)
m/s2
RateOfTurnHR (DataID 0x8040)
rad/s
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Links to the latest available documentation can be found via the following link: Xsens MTi Documentation