Xsens MTi-30 AHRS 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 [email protected]m
internet www.xsens.com
10557 Jefferson Blvd,
Suite C
CA-90232 Culver City
USA
phone [phone]
fax [phone]
e-mail [email protected]m
internet www.xsens.com
Document MT0605P, Revision F, 29 October 2018
MTi 10-series and MTi 100-series
5th generation
MTi User Manual

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Revisions
Revision
Date
By
Changes
A
26 Sep 2012
MHA
Initial release
…
….
…
J
14 August 2017
MHA
New version for 5th generation (sensor specifications,
hardware connections)
Removed MTw from product history
Grouped legacy products in product history
Corrected number of stop bits
Added 1 PPS specifications
Removed legacy USB converter specifications
2018.A
28 February 2018
AVY
Updated Section 5.2.3 with heading definition, revised
mounting considerations for MTi-G-710 for use with
Automotive filter profile.
…
…
…
…
2018.C
17 April 2018
AVY
Updated performance specifications
2018.D
25 June 2018
SGI
Added details on alternative UART communication
Added online documentation link to references section
Added note on GNSS platform supported
Online link for STEP files added
2018.E
1 July 2018
AVY
Updated MTi-G-710 orientation specification
© 2005-2018, 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
1REFERENCES ............................................................................................................................... 3
2XSENS HELP CENTER AND USER COMMUNITY ...................................................................... 4
3INTRODUCTION ............................................................................................................................ 5
3.1 MTI 10-SERIES ............................................................................................................................. 5
3.1.1 MTi-30 AHRS..................................................................................................................... 5
3.1.2 MTi-20 VRU ....................................................................................................................... 5
3.1.3 MTi-10 IMU ........................................................................................................................ 5
3.2 MTI 100-SERIES ........................................................................................................................... 6
3.2.1 MTi-G-710 GNSS/INS ....................................................................................................... 6
3.2.2 MTi-300 AHRS................................................................................................................... 6
3.2.3 MTi-200 VRU ..................................................................................................................... 6
3.2.4 MTi-100 IMU ...................................................................................................................... 6
3.2.5 Identifying device functionality using the unique Device Identifier .................................... 7
3.2.6 Product code...................................................................................................................... 8
3.3 EVOLUTION OF MTI PRODUCTS...................................................................................................... 9
3.4 OVERVIEW MTI DEVELOPMENT KIT................................................................................................ 9
3.4.1 Contents............................................................................................................................. 9
3.5 INSTALLATION............................................................................................................................. 10
3.5.1 Transient accelerations.................................................................................................... 10
3.5.2 Vibrations ......................................................................................................................... 10
3.5.3 Magnetic materials and magnets..................................................................................... 11
3.6 TYPICAL USER SCENARIOS.......................................................................................................... 11
3.6.1 MT Software Suite ........................................................................................................... 11
3.6.3 Using the Software Development Kit (SDK) .................................................................... 13
3.6.4 Direct low-level communication with MTi......................................................................... 14
3.6.5 Terms of use of MT Software Suite ................................................................................. 14
4MTI SYSTEM OVERVIEW ........................................................................................................... 16
4.1 CALIBRATION.............................................................................................................................. 16
4.2 XSENS KALMAN FILTER FOR VRU AND AHRS PRODUCT TYPES .................................................... 16
4.2.1 Using the acceleration of gravity to stabilize inclination (roll/pitch) ................................. 16
4.2.2 Using the Earth magnetic field to stabilize yaw ............................................................... 17
4.2.3 Estimating gyro bias in magnetic disturbed environments .............................................. 17
4.2.4 Initialization ...................................................................................................................... 17
4.2.5 XKF3i filter profiles........................................................................................................... 17
4.3 XSENS SENSOR FUSION ALGORITHM FOR MTI-G-710.................................................................... 18
4.3.1 Transient accelerations.................................................................................................... 19
4.3.2 Magnetic disturbances..................................................................................................... 19
4.3.3 Loss of GNSS .................................................................................................................. 19
4.3.4 MTi-G-710 filter profiles ................................................................................................... 19
4.3.5 GNSS Platform ................................................................................................................ 20
4.4 ACTIVE HEADING STABILIZATION (AHS)....................................................................................... 20
4.5 IN-RUN COMPASS CALIBRATION (ICC) ......................................................................................... 21
5OUTPUT SPECIFICATION .......................................................................................................... 22
5.1 OVERVIEW OF DATA OUTPUTS...................................................................................................... 22
5.1.1 MTData2 output in XBus protocol.................................................................................... 22
5.1.2 ASCII output (NMEA)....................................................................................................... 22
5.2 COORDINATE SYSTEMS ............................................................................................................... 22

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5.2.1 Calibrated inertial data and magnetic field data .............................................................. 22
5.2.2 Delta_angle and delta_velocity........................................................................................ 23
5.2.3 Orientation data ............................................................................................................... 23
5.2.4 Velocity data .................................................................................................................... 25
5.2.5 Position data .................................................................................................................... 25
5.3 ORIENTATION PERFORMANCE SPECIFICATION ............................................................................... 25
5.4 POSITION AND VELOCITY PERFORMANCE SPECIFICATION (MTI-G-710) .......................................... 26
5.5 SENSOR DATA PERFORMANCE SPECIFICATION .............................................................................. 27
5.5.1 Gyroscopes...................................................................................................................... 27
5.5.2 Accelerometers and magnetometer ................................................................................ 27
5.5.3 Barometer ........................................................................................................................ 28
5.5.4 GPS/GNSS receiver ........................................................................................................ 28
5.6 BUILT-IN SELF-TEST .................................................................................................................... 29
5.7 TEST AND CALIBRATION PARAMETERS.......................................................................................... 29
5.8 SENSORS DATA OUTPUTS............................................................................................................ 30
5.8.1 Physical sensor model..................................................................................................... 30
5.8.2 Calibrated delta_q and delta_v outputs ........................................................................... 31
5.8.3 Calibrated inertial and magnetic data outputs ................................................................. 31
5.8.4 Free acceleration ............................................................................................................. 32
5.8.5 Uncalibrated raw output mode......................................................................................... 32
5.9 RESET OF REFERENCE CO-ORDINATE SYSTEMS ............................................................................ 32
5.10 TIMESTAMP AND PACKET COUNTER OUTPUT ................................................................................. 32
5.11 STATUS BYTE ............................................................................................................................. 32
6COMMUNICATION....................................................................................................................... 33
6.1 COMMUNICATION TIMING............................................................................................................. 33
6.2 TRIGGERING AND SYNCHRONIZATION ........................................................................................... 33
6.3 INTERNAL CLOCK ACCURACY ....................................................................................................... 33
6.3.1 Clock of MTi’s without GNSS receiver............................................................................. 33
6.3.2 Clock of MTi-G-710.......................................................................................................... 33
6.4 SERIAL CONNECTION SETTINGS .................................................................................................. 34
6.4.1 Serial or USB communication.......................................................................................... 34
6.4.2 Transceiver voltage levels ............................................................................................... 34
7PHYSICAL SPECIFICATIONS .................................................................................................... 35
7.1 PHYSICAL PROPERTIES OVERVIEW ............................................................................................... 35
7.2 POWER SUPPLY .......................................................................................................................... 35
7.2.1 Power consumption specification .................................................................................... 35
7.2.2 Alternative 3V3 power supply .......................................................................................... 36
7.3 MECHANICAL AND ELECTRICAL INTERFACE SPECIFICATIONS .......................................................... 36
7.3.1 Encased MTi connectors overview .................................................................................. 36
7.3.2 OEM connections overview ............................................................................................. 38
7.3.3 Additional interface specifications.................................................................................... 40
7.3.4 Cable specifications ......................................................................................................... 41
7.3.5 Using the MTi Mk5 with an external USB converter ........................................................ 41
7.4 HOUSING MECHANICAL SPECIFICATIONS ....................................................................................... 41
7.4.1 Environmental protection of the housing ......................................................................... 41
7.4.2 Dimensions MTi ............................................................................................................... 42
7.4.3 Mounting the MTi-OEM.................................................................................................... 42
7.4.4 MTi 10-series technical drawing ...................................................................................... 43
7.4.5 MTi 100-200-300 technical drawing ................................................................................ 44
7.4.6 MTi-G-700/710 technical drawing.................................................................................... 45
7.4.7 MTi OEM technical drawing............................................................................................. 46

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8IMPORTANT NOTICES ............................................................................................................... 47
8.1 SAFETY INSTRUCTIONS ............................................................................................................... 47
8.2 ABSOLUTE MAXIMUM RATINGS ..................................................................................................... 47
8.3 MAINTENANCE ............................................................................................................................ 47
8.4 EU DECLARATION OF CONFORMITY ............................................................................................. 48
8.5 FCC DECLARATION OF CONFORMITY........................................................................................... 49
8.6 WARRANTY AND LIABILITY............................................................................................................ 50
8.7 CUSTOMER SUPPORT ................................................................................................................. 50

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List of Figures
Figure 1: MTi 10-series............................................................................................................................ 5
Figure 2: MTi 100-series.......................................................................................................................... 6
Figure 3: Product codes of MTi devices .................................................................................................. 8
Figure 4: Example of a label showing the SN (DeviceID) and the product code .................................... 8
Figure 5: MTi Development Kit................................................................................................................ 9
Figure 6: Structure of the MT Software Suite ........................................................................................ 12
Figure 7: Functionality implementation for specific products ................................................................ 14
Figure 8: coordinate system of the encased MTi (Note: origin is located at the accelerometers) ........ 23
Figure 9: Coordinate system of the MTi-OEM (Note: origin is located at the accelerometers)............. 23
Figure 10: Drawing of CA-USB-MTi ...................................................................................................... 36
Figure 11: Drawing of CA-MP2-MTi ...................................................................................................... 37
Figure 12: The pins of the headers on the MTi-OEM are clearly marked ............................................. 39
Figure 13: Standard ribbon cables can be used for connecting the MTi OEM to another board.......... 40
Figure 14: Using a heat shrink tube to position the mounting screws................................................... 42
Figure 15: MTi 10-series technical drawing........................................................................................... 43
Figure 16: MTi 100-series technical drawing......................................................................................... 44
Figure 17: MTi-G-710 technical drawing ............................................................................................... 45
Figure 18: MTi OEM technical drawing ................................................................................................. 46
List of Tables
Table 1: Device ID's for 5th generation MTi ............................................................................................ 7
Table 2: Evolution of MTi products.......................................................................................................... 9
Table 3: Guidelines for the use of the MT Software Suite..................................................................... 15
Table 4: Filter profiles for the MTi-200/MTi-300 .................................................................................... 18
Table 5: Filter profiles for the MTi-G-710 GNSS/INS ............................................................................ 19
Table 6: 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). ........................................................................................................................................... 24
Table 7: Orientation performance specification..................................................................................... 26
Table 8: Position and velocity performance specifications (MTi-G-710)............................................... 27
Table 9: Gyroscope specifications ........................................................................................................ 27
Table 10: Accelerometers and magnetometers specification ............................................................... 28
Table 11: Magnetometer specifications................................................................................................. 28
Table 12: Barometer specification......................................................................................................... 28
Table 13: GNSS receiver specification.................................................................................................. 29
Table 14: Output specifications ∆q and ∆v outputs............................................................................... 31
Table 15: Output specifications inertial and magnetometer data outputs ............................................. 31
Table 16: Output specifications Sensor Component Readout (SCR) ................................................... 32
Table 17: Transceiver voltage levels..................................................................................................... 34
Table 18: Physical properties overview................................................................................................. 35
Table 19: Power consumption depending on communication interface................................................ 35
Table 20: Pin configuration CA-USB-MTi.............................................................................................. 37
Table 21: Pin Configuration table CA-MP2-MTi .................................................................................... 38
Table 22: Part numbers headers on MTi OEM...................................................................................... 38
Table 23: Pin connections OEM headers.............................................................................................. 39
Table 24: Part numbers for sockets that fit the headers on the MTi OEM ............................................ 40
Table 25: Interface specifications of the synchronization lines ............................................................. 40
Table 26: Wire colours in the USB converters ...................................................................................... 41

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1 References
Reference
id
Document description
[LLCP]
“MT Low-Level Communication Protocol Documentation.pdf”, document ID
MT0101P
[MTM]
“MT Manager User Manual.pdf”, document ID MT0216P
[XDA_DOC]
XDA doxygen HTML documentation. Found in Xsens folder structure
[MTI_1]
“MTi 1-series Datasheet.pdf”, document ID MT0512P
Note: The latest available documentation can be found in your MT Software Suite installation folder or
via the following link: https://xsens.com/xsens-mti-documentation

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2 Xsens Help Center and User Community
Xsens has an extensive help center, a place where users of Xsens and Xsens employees (support, field
application engineers, sales and R&D engineers) meet. The knowledge base contains tips and tricks,
guidance and answers to frequently asked questions. News is also shared at the knowledge base and
it is possible to ask additional questions (registration required).
The user community is the place to ask questions. Answers may be given by other users or by Xsens
employees. The response time in the user community is significantly shorter than the response time at
Xsens support.
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.

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3 Introduction
This manual gives an overview of the 5th generation products and its usage. For previous generations,
refer to User Manual revision I (20 December 2016). Refer to section 3.2.5 to identify the generation of
your MTi. The MTi product portfolio from Xsens currently has 11 family members ranging in functionality
from inertial measurement units (IMU’s) to a fully integrated GNSS/INS solution. All products contain a
3D inertial sensor assembly (ISA: gyroscopes and accelerometers) and 3D magnetometers, with
optionally a barometer and GNSS receiver.
The MTi product range is divided in three series, the MTi 1-series, the MTi 10-series and the MTi 100-
series. The MTi 10-series is Xsens’ entry level model with robust accuracy and a limited range of IO
options. The 100-series is a new class of MEMS IMU’s, orientation and position sensor modules offering
unprecedented accuracies and a wide array of IO interfaces. The MTi 1-series is a low-cost module for
SMD assembly. Refer to [MTI_1] for more information on the MTi 1-series.
All MTi’s have a powerful multi-processor core. It processes IMU, magnetometer and barometer signals
with extremely low latencies, and gives several outputs: calibrated 3D linear acceleration, rate of turn
(gyroscope data), (earth) magnetic field and atmospheric pressure (100-series only) data along with
sensor fusion estimates of roll, pitch and yaw. The MTi-G-710 GNSS/INS also offers 3D position and
3D velocity. Over 50 various output formats can be retrieved directly from the MTi. Refer to [LLCP] for
more information on the available outputs per device.
This documentation describes the use, basic communication interfaces and specifications of all the 7
MTi’s in the MTi 10-series and MTi 100-series. Where they differ is clearly indicated. All products are
designed to be interchangeable from a mechanical and software interface point of view.
3.1 MTi 10-series
The MTi 10-series is the basic product range of the MTi product portfolio,
offering inertial and orientation data at an affordable price. The MTi 10-
series consists of 3 products that have various integration levels.
The MTi-10 series can easily be recognized by the silver base plate.
There are no visual differences among the MTi-10 IMU, MTi-20 VRU and
MTi-30 AHRS devices, other than their label marking
3.1.1 MTi-30 AHRS
The MTi-30 AHRS is a full gyro-enhanced Attitude and Heading Reference System (AHRS). It give
various outputs: drift-free roll, pitch and true/magnetic North referenced yaw, plus sensor
measurements: 3D acceleration, 3D rate of turn and 3D earth-magnetic field data. All products of the
MTi 10-series can also give processed data output from the strapdown integration algorithm (orientation
and velocity increments ∆q and ∆v).
3.1.2 MTi-20 VRU
The MTi-20 VRU is a 3D vertical reference unit (VRU), which means that it gives the same data as the
MTi-30, except for the referenced yaw. The yaw is unreferenced, though still superior to just gyroscope
integration, when using the gyro bias estimation techniques available.
3.1.3 MTi-10 IMU
The MTi-10 IMU is a 3D inertial measurement unit (IMU) that gives 3D acceleration, 3D rate of turn and
3D earth-magnetic field data, so it does not process data to orientation. The MTi-10-IMU can be set to
a data output generated by the strapdown integration algorithm (orientation increments ∆q and velocity
increments ∆v).
Figure 1: MTi 10-series

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3.2 MTi 100-series
The MTi-100 series is the high-performance product
range of the MTi product portfolio, with accuracies
surpassing conventional MEMS AHRS’s, because of
the use of superior gyroscopes and a new optimization
filter, going beyond (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 base plate and the holes on one side of the
casing. These holes are used for the adaptation of the
inside air pressure to atmospheric pressure, required
for a proper functioning of the barometer. Note that the
electronics inside are protected with a vent that keeps
the casing IP67 rated. There are no visual differences
among the MTi-100 IMU, MTi-200 VRU and MTi-300
AHRS, other than their label markings. The MTi-G-710 has an extra SMA connector to allow a
GPS/GNSS antenna to be attached.
3.2.1 MTi-G-710 GNSS/INS
The flagship of the MTi product portfolio is the MTi-G-710 GNSS/INS, a fully integrated solution that
includes an onboard GNSS receiver (GPS, GLONASS, BeiDou, Galileo and QZSS). The MTi-G-710-
GNSS/INS can thus not only give GNSS-enhanced 3D orientation output; it also gives AHRS-
augmented 3D position and velocity outputs. Furthermore, it provides 3D sensors data, such as
acceleration, rate of turn, magnetic field, the PVT (position, velocity, time) data of the GNSS receiver
and static pressure. Data generated from the strapdown integration algorithm (orientation and velocity
increments ∆q and ∆v) are available, as along with other processed data, at 400 Hz.
3.2.2 MTi-300 AHRS
The MTi-300 AHRS is a full gyro-enhanced Attitude and Heading Reference System (AHRS). It gives
drift-free roll, pitch and true/magnetic North referenced yaw outputs. It also gives sensors data and
processed data from the strapdown integration algorithm as well as described in section 3.2.1.
3.2.3 MTi-200 VRU
The MTi-200 VRU is a 3D vertical reference unit (VRU) and this unit runs the Xsens sensor fusion
algorithm from the MTi-300 as well. The difference between the data of the MTi-300 and MTi-200 is that
yaw is unreferenced, though the yaw is still much better than just integrating rate of turn when using the
gyro bias estimation techniques available. The MTi-200 also comes with Active Heading Stabilization.
3.2.4 MTi-100 IMU
The MTi-100 IMU is a 3D inertial measurement unit (IMU) that gives 3D acceleration, 3D rate of turn
and 3D earth-magnetic field data. The MTi-100-IMU can also be configured that it gives data generated
by the strapdown integration algorithm (orientation increments ∆q and velocity increments ∆v).
Figure 2: MTi 100-series
including the MTi-G-710

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3.2.5 Identifying device functionality using the unique Device Identifier
Each Xsens product is marked with a unique serial device identifier referred to as the DeviceID. The
DeviceID is categorized per MTi product configuration in order to make it possible to recognize the MTi
(and thus its functionality and interface) by reviewing the DeviceID. The second digit of the DeviceID
denotes the functionality (e.g. ‘1’ for MTi-10 and MTi-100), the third digit denotes the product series (6
for MTi 10-series, 7 for MTi 100-series) and the fourth digit denotes the interface (e.g. ‘0’ for
RS232+USB). The last four digits are unique for each device; these four digits have a hexadecimal
format.
The 4th generation MTi’s can be identified by the last four digits of the DeviceID (or SerialNumber). If the
last four digits are lower than hexadecimal 2000 they are the 4th generation MTi’s, otherwise they belong
to the 5th generation of MTi devices. Refer to version MTi User Manual rev I (20 Dec 2016) when you
have an MTi with one of these DeviceIDs
Below is a list of the product types with their associated DeviceIDs.
Table 1: Device ID's for 5th generation MTi
Product (MTi Mk5)
Multi-protocol
RS232+USB
RS422
RS485+USB
MTi-10 IMU
0168xxxx
0169xxxx
016Bxxxx
MTi-20 VRU
0268xxxx
0269xxxx
026Bxxxx
MTi-30 AHRS
0368xxxx
0369xxxx
036Bxxxx
MTi-100 IMU
0178xxxx
0179xxxx
017Bxxxx
MTi-200 VRU
0278xxxx
0279xxxx
027Bxxxx
MTi-300 AHRS
0378xxxx
0379xxxx
037Bxxxx
MTi-G-710 GNSS/INS
0778xxxx
0779xxxx
077Bxxxx

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3.2.6 Product code
The product code of the MTi Mk5 consists of a number of characters that represent the product type,
full ranges of the inertial sensors, the interface and the casing option. Figure 3 shows the product code
build-up, e.g. MTi-10-4A8G4 is an IMU with RS485 interface, 20g full range on the accelerometers and
450 deg/s full range for the gyroscopes.
Note that not every combination is available.
Figure 3: Product codes of MTi devices
Product
type
Interface:
2=RS232
4= RS485
6= RS422
Accelerometer:
A8=20g
Gyroscope:
G4=450º/s
G0=1000º/s
Version:
(blank) = encased
-O = OEM
Figure 4: Example of a label showing the
SN (DeviceID) and the product code

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3.3 Evolution of MTi products
The MTi 10-series and MTi 100-series are described in detail in section 3.1 and 3.2, for completeness
they are listed below as well.
Table 2: Evolution of MTi products
Product name
Description
Availability
Product photo
MTi 10-series,
MTi 100-series
(including MTi-G-
700/710) and
OEM
The 4th generation Motion Trackers of
Xsens (MkIV).
Introduced:
2012
Status:
Inactive
MTi 1-series
The MTi 1-series is a full range module
(IMU, VRU, AHRS and GNSS/INS) in a
miniature SMD form factor. The MTi 1-
series is not described in this manual.
For MTi 1-series, see [MTI_1].
Introduced:
2015
Status:
Active
MTi 10-series,
MTi 100-series
(including MTi-G-
710) and OEM
The new 5th generation of the MTi
series. The product will replace the 4th
generation MTi and has significantly
higher specifications in e.g. acceleration
and MTBF.
Introduced:
2017
Status:
Active
3.4 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. On the right, the
Development Kit is shown, containing an MTi and cable. All software and
installation instructions are available online.
The full content of the MTi DK is described below.
3.4.1 Contents
Your MTi
USB cable (CA-USB-MTi); multi-purpose cable (CA-MP2-MTI) on
request
Test and Calibration certificate
MT Software Suite available via www.xsens.com/setup
oXsens MTi USB driver
oMT Manager GUI for Linux and Windows
oMT Software Development Kit (MT SDK) for multiple OS
XsensDeviceApi.DLL, 32-bit and 64-bit (Windows)
DLL C and C++ interface
COM interface
XDA public source files (C, C++ wrapper ; any OS)
Example source code and examples (Windows)
MATLAB: DLL example supported from MATLAB 2010b
Figure 5: MTi Development Kit

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C: DLL example
C++: public source example and DLL example
Example source code and examples (Linux)
C-example
C++-public source example
oMagnetic Field Mapper –MFM (Windows and Linux)
MFM SDK (Windows and Linux)
oDocumentation
MTi User Manual [MT0506P]
MTi 1-series Data sheet [MT0512P]
MTi-3 DK User Manual [MT0513P]
MT Low Level Communication Documentation [MT0101P]
MT Magnetic Field Mapper Documentation [MT0202P]
XDA doxygen HTML API documentation
MTi Whitepaper
Firmware Updater User Manual [FU0100P]
oFirmware Updater (Windows)
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:
https://base.xsens.com/hc/en-us/articles/207003759
3.5 Installation
3.5.1 Transient accelerations
The 3D linear accelerometers in the MTi are primarily used to estimate the direction of gravity to obtain
a reference for attitude (pitch/roll). During long periods (more than tens of seconds) of transient “free”
accelerations (i.e. 2nd derivative of position) the observation of gravity cannot be made. The sensor
fusion algorithms can mitigate these effects to a certain extent, but nonetheless it is impossible to
estimate true vertical without additional information.
The impact of transient accelerations can be minimized when you take into account a few things when
positioning the device when installing it in the object you want to track/navigate/stabilize or control.
If you want to use the MTi to measure the dynamics of a moving vehicle/craft it is best to position the
measurement device at a position close to the centre of rotation (CR) of the vehicle/craft. Any rotations
around the centre of rotation translate into centripetal accelerations at any point outside the center of
rotation. For the MTi-G-710 with a valid GNSS-fix, the detrimental effect of transient accelerations on
orientation estimates is overcome by integrating with GNSS measurements in the sensor fusion engine.
The MTi 100-series copes better with transient “free” accelerations because of the higher-class
gyroscopes in the MTi 100-series. Next to the better hardware, the algorithm in the MTi 100-series is
superior in detecting and coping with challenging conditions, such as transient accelerations.
3.5.2 Vibrations
The MTi samples IMU signals at 10kHz per channel, processing them using a strapdown integration
algorithm with coning/sculling compensation. Proper coning/sculling compensation already mitigates
errors that poorly designed signal processing pipelines introduce when the device is under vibration. For
best results however, it is recommended that the MTi be mechanically isolated from vibrations as much
as possible: since vibrations are measured directly by the accelerometers, the following two conditions
can make the readings from the accelerometers invalid;

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1. The magnitude of the vibration is larger than the measurement range of the accelerometer. This
will cause the accelerometer to saturate, which may be observed as a “drift” in the zero-level of
the accelerometer. This will show up as an erroneous roll/pitch.
2. The frequency of the vibration is higher than the bandwidth of the accelerometer. In theory, such
vibrations are rejected, but in practice they can still give rise to aliasing, especially if close to the
bandwidth limit. This can be observed as a low frequency oscillation. Further, high frequency
vibrations often tend to have large acceleration amplitudes (see item 1).
There is an effect on the gyroscopes as well and especially when the vibrations include high-frequent
coning motion, the gyroscope readings may become invalid. The MTi 100-series features mechanical
vibration rejecting gyroscopes, designed to better cope with these specific conditions.
Note that the moving part on the Fischer connector can move to enable mating and unmating of the
cable with the MTi. The ring behind the moving part must be locked to prevent vibrations of the moving
parts of the connector to be transferred to the casing of the MTi.
Xsens has tested a set of vibration dampeners on the MTi. Vibration dampeners are low-profile rubber
cylinders that allow the MTi to be mounted on an object without a direct metal to metal connection that
transduces vibrations from the object to the MTi. The vibration dampeners have been tested with
frequencies up to 1200 Hz that caused aliasing when the MTi was mounted directly on the vibration
table had no effect with the vibration dampeners fitted. The dampeners tested are manufactured by
Norelem and have part number 26102-00800855, www.norelem.com
3.5.3 Magnetic materials and magnets
When an MTi is placed close to or on an object that is either magnetic or contains ferromagnetic
materials, the measured magnetic field is distorted (warped) and causes an error in the computed yaw.
The earth magnetic field is altered by the presence of ferromagnetic materials, permanent magnets or
power lines with strong currents (several amperes) in the vicinity of the device. The distance to the object
and the amount of ferromagnetic material determines the magnitude of disturbance introduced. Errors
in estimated yaw due to such distortions can be quite large, since the earth magnetic field is very weak
in comparison to the magnitude of the sources of distortion.
For more information on how to mitigate the detrimental effects of magnetic distortion, refer to this BASE
article: https://base.xsens.com/hc/en-us/articles/115004479409
3.6 Typical User Scenarios
This section is intended to help you find the right software component and corresponding documentation
for the way you want to use your MTi.
3.6.1 MT Software Suite
The MT Software Suite is a set of software components that can be used to communicate with the MTi
and to perform more high-level routines, such as logging, exporting, a magnetic field calibration and
updating of the firmware. Depicted in Figure 6 is a flow chart based on the software platform and the
preferred interface level.
On the left, three programs with GUIs are shown (Firmware Updater, Magnetic Field Mapper and MT
Manager). These programs offer the possibility to configure the MTi in a very easy way. The MT Manager
can also be used to communicate with the MTi. The MagField Mapper is also available as an SDK for
integration into another application.
The MT SDK contains all the developer code, such as a DLL, a shared object and basic functionality in
source code for embedded systems. Of course, it is possible to use lower level communication options,

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down to the Xbus Low Level protocol; most of the functionality however can be found in the DLL and
shared object.
Figure 6: Structure of the MT Software Suite
The Xbus low-level protocol is described in high detail in the Low Level Communication Protocol: [LLCP].
The hardware driver of the USB interface for Linux can be found on https://github.com/xsens/xsens_mt.
The driver is also included in Linux kernel 3.9 and higher.
3.6.2 Getting Started with the MT Manager
The easiest way to get started with your MTi is to use the MT Manager software for Windows 7, Windows
8 and Windows 10.
This easy to use software with a Windows user interface allows you to:
record data and playback/review data
view orientation, position and velocity in real-time (if available)
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
change and view various device settings and properties
reprocess pre-recorded data, e.g. with different settings
The MT Manager is therefore an easy way to get to know and to demonstrate the capabilities of the MTi
and to configure the device easily to suit your needs.
With the MT Manager, it is possible to apply a configuration profile to multiple MTi’s. This allows system
integrators to configure MTi’s correctly with a quick turn-around time.
Please refer to the MT Manager User Manual [MTM] for more information on this topic.

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3.6.3 Using the Software Development Kit (SDK)
This chapter gives an introduction to the Xsens Device API (XDA). It serves as a starting point for system
integrators interested in assessing the basis of the SDK and knowing about the background
considerations. The main objective of the SDK is to facilitate easy development of user-specific host
applications based on Xsens motion trackers.
The MT SDK 4.x (and the MT Software Suite) is designed for the MTi 1-series, MTi 10-series and MTi
100-series.
3.6.3.1 Using the Source code and Dynamic Library
The MT SDK consists of Source code and a Dynamic Library. Source code is made available in C, since
this language can be handled by many other programming languages, such as C++, Java and Python.
Since C++ is a more convenient language to use for first-time users of the MT SDK (lower risk of making
mistakes, easier to handle complex functions), Xsens also supplies a C++ wrapper around the C-
compiled library. Refer to the MT SDK documentation in the Xsens installation folder to find schematic
overview of the Xsens Device API. The host application developer can choose to use a COM, C, C# or
C++ interface. However, only the C interface is delivered as a compiled dynamic library. For the C# and
C++ interface the source code of the wrapper classes are supplied as part of the SDK. The interfaces
are discussed in more detail in the following sections.
Note that conceptually XDA makes no distinction between the cases of real-time data stream from a
device or a recorded file data stream.
Using the Xsens Xbus low-level communication protocol is discussed in section 3.6.4.
Device management and global control functions are grouped in the XsControl object. To access
functionality for a specific device the XsDevice object is available. Typical steps are:
1. Scan for Xsens devices with XsScanner::scanPorts
2. Open port with XsControl::openPort and get device object with XsControl::device
3. Configure device with XsDevice functions
4. Start measuring
C-interface libraries
XDA is implemented in two C-interface libraries that are supplied for Windows and Linux, consisting of
two parts:
XDA that contains the access to functionality as implemented in devices, e.g. configuring the Motion
Trackers, requesting data etc
XsTypes that contains generic types (vectors, matrices, quaternions, etc.) and some basic
operations on those types, e.g. converting quaternions coming from the MTi into Euler angles.
The C API exposes all possible functions that could be supported by an Xsens device. As such, a certain
functionality implemented in devices is accessible by a function call that takes at least an XsDevice
Object as a parameter. Not every Xsens device supports all functionality, e.g. an MTi-30 does not
support getting a position estimate whereas the MTi-G-710 does. This means that whether the function
returns a meaningful result depends on the type of connected device. The DeviceID indicates the MTi
product with associated functionality: a list of DeviceIDs can be found in section 3.2.5. Exposing all the
possible functionalities has the advantage that when changing the MTi in the application to a device with
other functionalities, the majority of the code can remain unchanged.

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Internally the Xsens host software is implemented using an object oriented approach in which the
functionality is only implemented in subclasses, see schematic below.
It is important for the developer to use only functions supported by the connected device. During run
time, calling an unsupported function will generate an error status in line with the normal error handling
framework.
C++ interface
To offer the convenience of object-lifetime management to developers, the XDA is also offered as a C++
interface which basically implements a convenience wrapper around the C API. This means that the
developer does not have to deal with memory management (i.e. easy object-lifetime management) as
the class implementation takes care of this. This means that for example functions named
XsDevice_<function name> in the C interface are available in the C++ interface as the <function
name> method of the XsDevice class.
COM interface
For MS Windows environments, all the functionality is also available via a COM interface.
3.6.4 Direct low-level communication with MTi
The MTi features a powerful embedded multi-processor core. As the MTi has an on-board non-volatile
memory that can store all settings, the MTi can conveniently be used without using a host computer.
The low-level communication protocol (named Xbus protocol) offers full control and functionality,
however without the convenience advantages that the Xsens Device API offers, such as threading,
object-oriented programming and error handling. Low-level communication is essential on platforms that
do not support the Xsens Device API, such as custom embedded computers.
The low-level communication is extensively described in the Low-Level Communication Protocol
Documentation. Next to that, source code is delivered to make driver development and Xbus message
parsing for the MTi as easy and quick as possible.
3.6.5 Terms of use of MT Software Suite
The installer of the MT Software Suite can install 4 components of the MT Software Suite: the MT
Manager, the MT SDK, the Magnetic Field Mapper and the MFM SDK. The Firmware Updater is a
Figure 7: Functionality implementation for specific products

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separate installer. The MT Software Suite has a Restricted License Agreement that you need to accept.
In the following table, the guidelines for use of each component are described.
Table 3: Guidelines for the use of the MT Software Suite
Component
Guidelines
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
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 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 and so each Xsens’ MTi is calibrated and
tested by subjecting each product 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
below.
4.2 Xsens Kalman Filter for VRU and AHRS product types
The orientation of the VRU and AHRS is computed by Xsens Kalman Filter. XKF3™is a proven sensor
fusion algorithm, which can be found in various products from Xsens and partner products. The industrial
applications version is XKF3i: it uses signals of the rate gyroscopes, accelerometers and
magnetometers to compute a statistical optimal 3D orientation estimate of high accuracy with no drift for
both static and dynamic movements.
The design of the XKF3i algorithm can be summarized as a sensor fusion algorithm where the
measurement of gravity (by the 3D accelerometers) and Earth magnetic north (by the 3D
magnetometers) compensate for otherwise slowly, but unlimited, increasing (drift) errors from the
integration of rate of turn data (angular velocity from the rate gyros). This type of drift compensation is
often called attitude and heading referencing and such a system is referred to as an Attitude and
Heading Reference System (AHRS).
4.2.1 Using the acceleration of gravity to stabilize inclination (roll/pitch)
XKF3i stabilizes the inclination (i.e. roll and pitch combined) using the accelerometer signals. An
accelerometer measures gravitational acceleration plus acceleration due to the movement of the object
with respect to its surroundings.
XKF3i uses the assumption that on average the acceleration due to the movement is zero. Using this
assumption, the direction of the gravity can be observed and used to stabilize the attitude. The
orientation of the MTi in the gravity field is accounted for so that centripetal accelerations or asymmetrical
movements cannot cause a degraded orientation estimate performance. The key here is the amount of
time over which the acceleration must be averaged for the assumption to hold. During this time, the rate
gyroscopes must be able to track the orientation to a high degree of accuracy. In practice, this limits the
amount of time over which the assumption holds true.
However, for some applications this assumption does not hold. For example, an accelerating automobile
may generate significant accelerations for time periods lasting longer than the maximum duration the
MT’s rate gyroscopes can reliably keep track of the orientation. This will degrade the accuracy of the
orientation estimates with XKF3i somewhat, because the application does not match the assumptions
made in the algorithm. Note however, that as soon as the movement again matches the assumptions
made, XKF3i will recover and stabilize. The recovery to optimal accuracy can take some time.
NOTE: To be able to accurately measure orientations as well as position in applications which can
encounter long-term accelerations we offer a solution that incorporates a GNSS receiver, the MTi-G-
710 GNSS/INS.