Vectornav VN-200 User manual

VN-200
Development Kit
Quick Start Guide

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Copyright © 2019 VectorNav Technologies, LLC
Thank you for purchasing the VN-200 Development Kit from VectorNav
Technologies. This Quick Start Guide will assist you in getting the VN-
200 configured and operational. It will also introduce some common
operations performed with the sensor. For more detailed information
please refer to the VN-200 User Manual, a copy of which is provided
with the Development Kit and is also available online at
www.vectornav.com/support.
Please do not hesitate to give us a call at +1.512.772.3615 or email us at
[email protected]om if there are any questions we can answer or if
we can be of any assistance.

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Copyright © 2019 VectorNav Technologies, LLC
VN-200 Introduction
The VN-200 is a miniature, surface-mount, high-performance GPS-Aided
Inertial Navigation System (GPS/INS). Incorporating the latest solid-state
MEMS sensor technology, the VN-200 combines a set of 3-axis
accelerometers, 3-axis gyros, 3-axis magnetometer, a barometric
pressure sensor, a 50-channel L1 GPS receiver, as well as a 32-bit
processor into a miniature surface-mount or standalone module. The
VN-200 couples measurements from the onboard GPS module with
measurements from the onboard inertial sensors to provide position,
velocity, and attitude estimates of higher accuracies and with better
dynamic performance than a standalone GPS module or Attitude
Heading Reference System (AHRS).

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VN-200 Installation
Mounting the VN-200
You may mount the VN-200 to the vehicle or platform in any
orientation. If the VN-200 axes do not align with the desired vehicle or
platform axes then a Reference Frame Rotation will be required to
remap the attitude, angular rates, acceleration, and other data to the
desired frame (see page 9).
When installing the VN-200 to a vehicle or other platform, ensure that:
•The VN-200 is rigidly mounted with respect to the GNSS
antenna
•The VN-200 is rigidly mounted to the aircraft, vehicle or other
platform.
oVibration dampeners or flexible mounts can degrade
the VN-200 performance and are not recommended.
•All harnesses are properly secured and strain-relieved to avoid
stress entering the VN-200 from the cabling.
•Great care is taken when connecting the GNSS antenna, as the
connector can sustain limited side loads and connecting cycles

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Copyright © 2019 VectorNav Technologies, LLC
Ground Planes
To prevent multipath ensure that the GNSS Antennas are mounted
directly to a ground plane. Below are good and bad ground plane
installation examples.
GNSS Antenna Ground Plane Installation
Good
Bad
•Antennas shipped with the development kit have a
manufacturer recommended 100 mm diameter ground plane
included
•There is no requirement for ground planes to be electrically
grounded
•Ground planes can be any thin piece of metal (even foil)
Mounting the GPS Antenna
The VN-200 requires connection to an active GPS antenna, mounted
with a clear view of the sky.
In order for the GNSS Compass to function optimally both antennas
must:
•have clear view of the sky
•have a ground plane installed directly underneath the antenna
or be mounted on large metal surface
•be mounted as flat as possible, minimize pitch/roll to < 10°
Ground Plane GPS Antenna

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Copyright © 2019 VectorNav Technologies, LLC
VN-200 Start Up Sequence
Time: 0 sec
The VN-200 is operating as an AHRS.
Using the on-board magnetometer for
coarse heading estimation
Time: +30 sec
GPS Fix acquired. Local magnetic
declination applied. VN-200 still
operating as AHRS.
The VN-200 needs to exceed 5 m/s for
more than 1 second to start dynamic
alignment
During dynamic alignment accel and
GPS data are correlated to produce
yaw estimate. Typically take 60
seconds of sufficient motion to
complete alignment.
VN-200 Heading uncertainty is now
below 2 degrees. Sensor operating
within specification.

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VN-200 Setup
Reference Frame Rotation
The VN-200 may be mounted in any orientation on the vehicle or
platform. The Refence Frame Rotation is a 3 x 3 rigid rotation matrix
that will map the sensor axes to the vehicle axes, this will enable the
VN-200 to output attitude, angular rates, acceleration, and other data in
the vehicle reference frame.
Sensor Orientation
Reference Frame Rotation
[1 0 0
0 1 0
0 0 1]
[−1 0 0
0 −1 0
0 0 1]
[0 −1 0
0 0 1
−1 0 0]
[0 0 1
0 1 0
−1 0 0]
Vehicle Frame
Sensor Frame

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Copyright © 2019 VectorNav Technologies, LLC
GPS Antenna A Offset
By default, the VN-200 assumes that GPS Antenna A is mounted within
10 centimeters of the VN-200 module itself. If GPS Antenna A is
mounted farther away than 10 centimeters in any direction then the
GPS Antenna A Offset Register must be specified to properly account for
the relative motion of the antenna with respect to the IMU. The VN-
200 defines the Antenna A offset as the distance from the VN-200 to
Antenna A in the X, Y, & Z directions defined by the Sensor Frame.
To configure the GPS Antenna A Offset, use Register ID 57 to input the
X, Y, & Z position of Antenna A with respect to the VN-200.
If the Reference Frame Rotation is implemented, then the Antenna
A offset must be specified in the X, Y, & Z directions of the Vehicle
Frame as defined by the Reference Frame Rotation matrix.

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Configuring the VN-200 in
Control Center
All VN-200 configuration registers can be set within Control Center using
the various dropdown items in the Config Registers View and stored in
non-volatile memory using the Write Settings command. The VN-200
will automatically startup in the configuration that was set when a Write
Settings command was issued. A Restore Factory Settings command will
reset the configuration to the default settings.
A copy of the Control Center GUI is included on the CD in the VN-200
Development Kit. Please also regularly check our website for the latest
version of the software.
http://www.vectornav.com/support/downloads
The following steps provide an example of how to connect to the VN-
200, configure the VN-200 output data, input the GNSS Compass
measurements, and view the VN-200 INS Status message through
startup and operation.
Some INS Filter configuration settings require a Reset command
after issuing a Write Settings command before taking effect.

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Connecting to the VN-200
When first working with the VN-200, we recommend connecting the
sensor to a PC running our Control Center GUI to gain familiarity with the
available configuration options and features.
1. Attach the USB or Serial Adapter Cable to the VN-200 using the cable
tool provided in the Development Kit. For the VN-200 Development
Board, you can connect and power the sensor through USB1 (J2
connector) or alternatively use the USB2 (J3) for power and the DB-9
(J4) for communication.
2. Connect to the VN-200 by selecting the correct COM port and
baudrate and clicking on the Connect button. The default baudrate
for the VN-200 is 115200.
The VN-200 can pull up to 100mA of current when the GNSS
antenna is connected. Ensure USB port compatibility prior to use.

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Copyright © 2019 VectorNav Technologies, LLC
Reference Frame Rotation Configuration
As mentioned earlier, the VN-200 can be mounted in any orientation. In
order to align the output axes with that of the vehicle frame you need to
configure the Reference Frame Rotation. The changes can be input by
either using the:
1. Simple Ref Frame Calc Tool
2. Advanced Ref Frame Cal Tool
3. Reference Frame Rotation Register located in:
Config Registers -> IMU -> Reference Frame Rotation
The simplest tool to use for the RFR configuration is the Simple Ref
Frame Calc tool that can be found under the Configuration menu item.
The Simple Ref Frame Calc will step you through aligning the VN-200
axes with the vehicle axes. There are three (3) steps:
a. What axis of the VN-200 aligns with the forward axis of the
vehicle?
b. What axis of the VN-200 aligns with the downward axis of
the vehicle?
c. Click Finish to write the new RFR to the sensor and reset
The RFR will only take affect after a reset. Ensure that you issue
Write Settings to save the configuration for the next power up.

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Use the 3D View to confirm the orientation of the VN-200 matches your
physical installation.

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Antenna A Offset Configuration
Input the X, Y, & Z GNSS Antenna A Offset measurements by expanding
the GNSS Antenna A Offset item under Config Registers -> GNSS.
Click the Write Register button in order to write the new configuration
to the sensor.
It is important to issue a Write Settings followed by a Reset
command after inputting the GNSS Compass Baseline
measurements to ensure the VN-200 initializes on the correct
values. Right-click on Write Settings in the Commands Window and
then click Execute Command. Next, right-click on Reset and then
click Execute Command.

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Copyright © 2019 VectorNav Technologies, LLC
Monitoring VN-200 Startup
Control Center will poll the VN-200 and display the INS Mode, GNSSFix
status flags in the Sensor Status window. It will also provide details of
the number of satellites used from Position, Velocity and Timing (PVT)
solution.
It is important to monitor these status messages during the startup
sequence to ensure that the INS Filter initialize properly.
The Sensor Status window provides a comprehensive overview of the
VN-200 status.

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Trouble Shooting
1. The heading/yaw is incorrect or drifts when stationary
The VN-200 is experiencing magnetic interference.
Move the sensor away from magnetic interference
Do an HSI calibration to compensate for local interference
2. No GPS fix or position is jumping when stationary
Likely problem is poor GPS conditions, poor satellite visibility or
multipath
Ensure the GPS antenna has a clear view of the sky
Move away from obstructions or large buildings
Ensure antenna is mounted directly to ground plane
3. The VN-200 is not getting into INS Mode 2
The VN-200 will only dynamically align with sufficient motion.
The vehicle/platform needs to exceed 5 m/s in order to
dynamically align
4. INS Mode toggles when in high dynamic maneuvers
The Lever Arm, Antenna A offset, is likely incorrect.
Check Antenna A Offset measurements are correct and in the
correct reference frame
5. The VN-200 altitude is incorrect
The VN-200 reports altitude above ellipsoid (WGS84) and not above
Mean Sea Level (MSL).

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VN-200 Installation and Setup
Checklist
Description
Yes/No
VN-200 Mounting
Is the VN-200 rigidly mounted?

Are the cables strain relieved?

Do you need a reference frame rotation?
[|_ _ _
_ _ _
_ _ _| ]

GNSS Antenna Mounting
Is the GPS antenna rigidly mounted?

Is the antenna on a flat and level surface?

Is the GPS Antenna mounted directly to a ground
plane?

Does the antenna have a clear view of the sky?

Measurements
Are the Antenna A Offset measurements in the Vehicle
Frame ?

X:
Y:
Z:
VN-200 Setup
Start Control Center

Connect Control Center to VN-200

Input Reference Frame Rotation into Control Center

Input GNSS Antenna A Offsets (X, Y, & Z)

Set COM Baudrate to: 115200

Set Async Data Output Type to: INS LLA

Set Async Data Output Frequency to: 40

Write Settings to Sensor Memory

VN-200 Startup Sequence
Are you outside?

Are you away from tall buildings?

Do you have a clear view of the sky?


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Connect the VN-200 to Control Center

Is GPS Fix: True

Is INS Mode: 1

Has your platform/vehicle exceed 5m/s

Is INS Mode: 2


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Additional References
•VectorNav VN-200 User Manual (UM0004)
www.vectornav.com/support/manuals
•VectorNav Development Tools
oControl Center
oC/C++ Library
o.NET Library
oEmbedded Firmware Library
oMATLAB Development Library
oEAGLE PCB Parts Library
www.vectornav.com/support/downloads
•Overview of Inertial Sensor Technology
www.vectornav.com/support/library