QUALISYS Q ACADEMY AMTI GEN 5 Technical Document

QUALISYS AB
Kvarnbergsgatan 2 · 411 05 Gothenburg · SWEDEN
Tel. [phone] · Fax [phone]
[e-mail] · www.qualisys.com

1
INTRODUCTION
The AMTI Gen 5 system allows you to connect and
control AMTI force plates. The system works through a
digital amplifier that collects the force plate data and
transmits them to QTM in sync with the data being
collected by the Qualisys camera system.
This tutorial covers how to connect and begin using your
AMTI Gen 5 system with your Qualisys camera system.
For advanced settings beyond the scope of this tutorial,
please refer to your QTM manual or to your AMTI documentation.
CONTENTS
DOWNLOADING THE GEN 5 DRIVER............................................................................................................................2!
CONNECTING THE GEN 5 ........................................................................................................................................................4!
Computer to Gen 5.......................................................................................................................................................................4!
Camera system to Gen 5........................................................................................................................................................4!
SETTING UP THE GEN 5 IN QTM......................................................................................................................................5!
Installing the driver.......................................................................................................................................................................5!
Setting up in QTM.........................................................................................................................................................................6!
Setting the calibration parameters............................................................................................................................... 7!
L-FRAME PLACEMENT................................................................................................................................................................9!
LOCATING THE FORCE PLATE IN THE VOLUME .......................................................................................10!
Recording the force plate’s location ........................................................................................................................ 10!
Identifying the location in QTM......................................................................................................................................11!
Testing and changing the force plate’s orientation...................................................................................13!
SETTING A THRESHOLD.........................................................................................................................................................15!

DOWNLOADING THE GEN 5 DRIVER
2
DOWNLOADING THE GEN 5 DRIVER
The amplifier runs on the AMTI Gen 5 driver, which you will need to download before
connecting the amplifier. You only need to go through this process the first time you
use the Gen 5 system with this computer.
1. Open QTM and select your current project.
2. In QTM, open Project Options either by clicking the gear icon
near the top left of your screen or by typing the keyboard
shortcut Ctrl+W.
3. With the Input Devices window open, click “Download device drivers” near the
bottom right. The link will open a Qualisys webpage with updated device
drivers.
4. Click on the correct download link for “AMTI Gen 5 driver,” depending on
whether your computer runs 32-bit or 64-bit Windows, then click on the
downloaded file to view it on your computer.

DOWNLOADING THE GEN 5 DRIVER
3
5. The drivers will be in a compressed folder, so you will need to extract the
contents.
6. Follow the extraction instructions, choosing a location on your computer that
you will remember later on during installation.

CONNECTING THE GEN 5
4
CONNECTING THE GEN 5
In order to record and sync the force plate data through QTM, you’ll need to connect
your Gen 5 amplifier both to the computer and to the Qualisys camera system. You
will also need to make sure your force plate is connected to the amplifier according
to your AMTI documentation.
Computer to Gen 5
Your Qualisys computer connects to the Gen 5 system
through a USB Type A to Type B cable. Plug the squarish
end into the USB port on the back of the Gen 5 amplifier,
and plug the flat rectangular end into your computer.
Camera system to Gen 5
To synchronize the force plate data with your Qualisys camera system, you will need
to use the Sync/Trig splitter—a short cable with a single connector branching off into
two or three connectors (depending on the model)—and a long BNC cable.
1. Plug the single end of the Sync/Trig splitter into
the port labeled “CONTROL” on the back of the
nearest Qualisys camera, making sure to line up
the red dots before pushing in.
2. Connect the BNC cable to
the “Sync out” end of the
Sync/Trig splitter, twisting to
secure it.
3. Plug the other end of the
BNC cable into the
“GENLOCK/TRIGGER INPUT”
port on the back of the Gen 5.
The camera is now connected
to the amplifier.

SETTING UP THE GEN 5 IN QTM
5
SETTING UP THE GEN 5 IN QTM
Your computer should automatically prompt you to install the device driver when you
plug in the amplifier. If it doesn’t, open Device Manager, right-click on Gen 5, and click
on “Update Driver Software.”
Installing the driver
1. With the “Update Driver Software” window open on your computer, click on
“Browse my computer for driver software.”
2. Click “Browse,” then choose the folder to which you extracted the driver
earlier.

SETTING UP THE GEN 5 IN QTM
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3. Click “Next,” and Windows will install the driver.
4. When the installation finishes, click “Close.”
5. You will need to close QTM as well before continuing.
Setting up in QTM
Once the Gen 5 driver has been installed, reopen QTM and select your current
project so you can adjust the amplifier’s settings.
1. Open Project Options as before by clicking the gear icon near the top left of
your screen or by typing the keyboard shortcut Ctrl+W.
2. In the Input Devices window, you will see a green circle next to the AMTI Gen
5 indicating that the amplifier is plugged in. Select the checkbox next to it, and
“Force Plates” will now show up under Input Devices in the list to the left.
3. Click the plus sign beside “Force Plates,” then click on “Amti Gen 5” to change
its settings.

SETTING UP THE GEN 5 IN QTM
7
4. In the settings window, specify the camera number to which your amplifier is
connected by using the dropdown menu beside “Sync source.” (The number is
displayed in the bottom right-hand corner on the front of the camera.)
5. It is recommended to zero your force plate(s) before each trial, and you can
automate this by selecting one or both of the checkboxes under “Force plate
auto-zero.”
6. Click “OK” to save your settings.
Setting the calibration parameters
If you are using a digital force plate, QTM will receive the calibration matrix
automatically from the amplifier. However, if you are using an analog force plate, you
can set the calibration parameters manually.

SETTING UP THE GEN 5 IN QTM
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1. In the left pane of the Project Options window under “Processing,” click on the
plus sign next “Force Data” and then on “Amti Gen 5.”
2. Next, click on “Calibration” to input the force plate calibration parameters
(length, width, offsets, calibration matrix, etc.) according to your AMTI
documentation.
3. Click “OK” to save your calibration parameters and close the window.

L-FRAME PLACEMENT
9
L-FRAME PLACEMENT
Before starting data acquisition, you will need to calibrate the cameras so that the
computer will know exactly where the cameras are in respect to each other and to
the environment around them. This tutorial does not cover how to calibrate the
camera system, but it is important to note that the location of the force plate often
determines the origin point for calibration.
The L-frame is a tool that defines the X, Y, and Z axes of
the volume during calibration, and its corner sets the
origin point. Many labs choose to place the L-frame along
a force plate. Tabs on the L-frame are designed to slide
into the gaps beside the force plate to keep the L-frame
in place.
The L-frame does not have to
be placed on the force plate.
The important thing is that it be placed in the same spot
every time for consistent calibration results, and the force
plate is an easy reference point.

LOCATING THE FORCE PLATE IN THE VOLUME
10
LOCATING THE FORCE PLATE IN THE VOLUME
“The volume” is the area that the camera system will be viewing and recording, and
you will need to teach QTM the exact location of your force plate within the volume. If
you are connecting additional force plates, repeat this process for each one.
Recording the force plate’s location
1. Place a reflective marker on each of the four corners of your force plate.
2. With QTM open, start a new session by clicking on the blank
paper icon in the top left or by using the keyboard shortcut
Ctrl+N.
3. Your screen will automatically display the cameras’ views in 2D.
Change the view to 3D by clicking on the “3D” icon in the left bar of
the main pane or by using the keyboard shortcut 3. Now you will see a
single three-dimensional image with the four markers shown in red.
4. Begin a new trial by clicking the icon at the top of your
screen that looks like a red circle or using the keyboard
shortcut Ctrl+M.
5. Set the Capture Period to 1 second and click “Start.”

LOCATING THE FORCE PLATE IN THE VOLUME
11
6. Once the trial is finished recording, press the “Ctrl” button on your keyboard
while clicking on the four markers to select them all.
7. Drag them into the empty right pane called “Labeled trajectories.”
Identifying the location in QTM
1. Open Project Options as before by clicking the gear icon near the top left of
your screen or by typing the keyboard shortcut Ctrl+W.
2. In the left pane of the window that opens, click on the plus sign beside “Force
Data,” then click on “Amti Gen 5” to view its settings.

LOCATING THE FORCE PLATE IN THE VOLUME
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3. Click on “Generate,” and QTM will automatically identify the location of the
force plate.
4. However, it will not automatically know which direction the force plate is
oriented, and it will give more than one possible solution. Click “OK” to select
between them.
5. The easiest way to choose between the orientation solutions is to pick one
and then test it for accuracy. Change the option using the dropdown menu or
leave it as is and click “OK” to try it out.

LOCATING THE FORCE PLATE IN THE VOLUME
13
6. Click “OK” to close the Force Plate Location window that pops up.
7. Click “OK” to save the settings and close the Project Options window.
Testing and changing the force plate’s orientation
1. Start a new session as before by clicking on the blank paper icon in the top
left or by using the keyboard shortcut Ctrl+N. There is no need to save the
current measurement.
2. Click the “3D” icon or type 3, and you will see a 3D view of the force plate.
3. One way to test is to step on one end of the force plate while keeping an eye
on your computer screen. The force arrow should point toward you. Another
way to test is to walk over the force plate as if during a gait trial. If the motion
of the arrow on screen corresponds with normal gait ground reaction forces,
the force plate is oriented correctly in QTM.
4. If the motion is backwards from what you’d expect with normal gait, you will
need to change the orientation. Reopen the force plate’s settings under Force
Data in the Project Options window, and click on “View/Edit.”

LOCATING THE FORCE PLATE IN THE VOLUME
14
5. At the bottom left of the window that opens, click “Rotate 180 degrees.” Click
“OK” to save.
6. Retest as above to confirm that the force plate is now oriented correctly within
QTM.

SETTING A THRESHOLD
15
SETTING A THRESHOLD
If you need to filter out low-level signal noise, you can set a threshold in the same
force plate’s settings window under “Force Data.” In the middle of the settings
window, click the “Activate” checkbox under “COP (Center of Pressure) threshold,”
and then set the minimum amount of vertical force required to activate the force
plate’s data recording.
Keep in mind that any forces below this threshold will not be recorded, so this setting
is only recommended when necessary and when not trying to measure small forces.
Now you are ready to use the AMTI Gen 5 amplifier with your Qualisys camera
system.
This manual was produced by Qualisys AB and Bassett Biomechanics.
v. 1.0 · © 2017 Qualisys AB