ARIEL VECTOR PROGRAM
One of the most common
forces acting on the body is the ground reaction force, which acts on the foot
during standing, walking or running.
This force vector is three dimensional, consisting of two shear
components (X and Y) acting parallel to the ground plus a vertical supporting
force (Z). These forces can be measured
using a multi-component force transducer.
This transducer is commonly know as a force platform. The force platform also provides the
location of the center of pressure of this ground reaction vector using the
relative vertical forces seen at each of the transducers.
It is often valuable to
combine the ground reaction force with the video data. The ARIEL VECTOR software is a
Windows based program for superimposing the 3-dimensional ground reaction force
vector onto an AVI video image using the Ariel Performance Analysis System
(APAS). Specialized laboratories
study these vectors with the goal of improving sports performance, evaluating
injuries or the effects of disease. The
VECTORS program provides the clinician with the tool to observe any deviations
between normal leg and foot alignments with the resultant force vector.
Although a few of VECTOR’s
features appear complex, they are relatively easy to master once you understand
the underlying concepts. This manual is
arranged to teach you these concepts in a logical order by showing you, in
step-by-step fashion, how to use the
VECTORS program.
A few of the new features
you will see in VECTORS version 1.0
1. Superimposing a Vector Over an AVI Image. Force vector is superimposed on
corresponding AVI file display.
Multiple windows can be opened for different views.
2.
Multiple Vector. Force vectors can be superimposed on AVI file display in a either
a “single,” “accumulate,” or “multiple” mode.
Multiple windows can be opened for different views.
3.
APAS Tool Bar. A toolbar has been added to
allow the user to activate individual APAS modules from within the main
programs.
4.
2D/3D Vector Display. Forces,
moments and COP information can be displayed in either 2D, 3D or graphical
format.
The following list
provides the basic guidelines for the necessary components of the VECTORS
program to provide the best possible performance. . The software requires a minimum of Microsoft Windows 95/98 and
APAS-2000 Revision 2.1 or later (with the VECTORS option).
1. AMTI or BERTEC Force Platform system with
Ariel software drivers.
2. One or more VHS/S-VHS Video Camera(s).
3. Ariel Performance Analysis System (APAS)
software used to Capture the corresponding *.AVI and *.ANA file formats.
Correct operation of the
VECTOR program is dependent upon the configuration of the force platform and
camera. While individual conditions may
vary, the recommended hardware setup and data collection procedures are
described below.
1.
Position the force platform. The force
platform should be placed to allow enough room for the camera to see all four
corners of the force platform and obtain the desired field of view.
2.
Position the video camera(s). The camera
should be placed with the viewing axis centered and perpendicular to any one of
the four sides of the force platform. Make certain that all four corners of the platform are visible
with enough vertical height to include the area of interest. If desired, multiple cameras can be used to
record both the X and Y axes. Two files
can then be opened in the VECTORS program to display the X and Y view axes
simultaneously.
3.
Determine the synchronizing event. Make
certain that there is a synchronizing event that is “visible” to both the
analog and video signals. This could be
something as simple as the foot contacting the force platform or an electronic
device that emits both a visible signal to the camera and an electronic signal
to the A/D module.
4.
Simultaneously collect AVI & ANA data. As the
subject stands/walks on the force platform, simultaneously record the event using
the Ariel ANALOG module and the video camera(s). As a reminder, the force plate should be zeroed prior to data
collection. Make certain to include the
SYNCHronizing event as close as possible to the data to be analyzed.
5.
Capture AVI file to APAS computer. Run the
Ariel CAPTURE module to capture the video image as an AVI format file to the
hard disk of the computer.
You are now ready to begin
the VECTOR program and open a new file.
Prior to performing the VECTORS
process, you should take the time to familiarize yourself with the format and
contents of the various screens listed below:
THE APAS TOOL BAR
You can activate any of
the APAS software modules from within the current program by selecting the
icons located on the APAS tool bar. The
tool bar is toggled on/off using the APAS Toolbar command in the VIEW menu. A check mark in the left column of the menu
indicates that the toolbar is currently active. The toolbar can be re-located anywhere in the main program window
by dragging it with the mouse. The
following program modules can be activated by clicking the appropriate
icon. Icons are pictorial
representations of programs, commands or functions.
THE TOOL BAR
You can activate many
functions by selecting the icons located on the VECTORS program tool
bar. The tool bar is located near the
top of the window. Icons are pictorial
representations of commands or functions.
You can access the following commands by clicking the appropriate icon.
THE VECTOR WINDOW LAYOUT
When a VECTOR file is
opened, additional windows will be displayed inside the main VECTOR
window. Multiple windows can be opened
simultaneously. The Vector Title
will be displayed at the top of each Vector Window. The Vector Window title incorporates the *.VEC filename that
consist of the *.ANA filename and the associated *.AVI file being used.
The Vector Window Status
bar is divided into three fields and is located at the bottom of each View
Window. The first field displays the Image
number of the currently displayed AVI file. When a vector file is opened, the program will default to Image
(Frame) #1.
The second field displays
the current Fxyz status. These
numbers represent the numerical values
for the three orthogonal forces (X, Y, Z) corresponding to the currently
displayed image and are used to compute the displayed vector image. These values are obtained directly from the
ANA file.
The Ax/y field
displays the current Ax/y status.
These numbers represent the numerical values for the X/Y coordinates of
the center-of-pressure along the respective axes from the center of the force
platform.
Scroll Bars located immediately above the View Status bar and
also at the right side of the View Window allow the image to be scrolled
left/right and up/down. The small arrow
in the upper right corner of the View Window can be used to expand the window
to the full screen.
THE STATUS BAR
The status bar provides
information about the current status of the image file. The status bar is located at the bottom of
the Vector window.
The far left side of the
status bar indicates the current status of the Vector file. This field will usually state READY. The far right side of the status bar
displays the currently selected IMAGE option.
When a new file is opened, this field will default to PAUSE. During the playback of the vector/image
file, this field will indicate the playback mode (i.e. Play Forward or Play Reverse).
1. Double-click the VECTORS icon located
in the APAS System window group.
The main Vectors window will appear.
The following steps are
recommended for correct operation of the VECTORS program.
1. Choose the NEW command from the FILE
menu. This will open a new *.VEC
document.
2. Select the VIDEO FILE command
from the FILE menu to open an associated Video (AVI) File.
3. Select the ANALOG FILE command from
the FILE menu to open an associated Analog (ANA) File.
4. Choose the DIMENSIONS command from
the SETUP menu to make certain the force platform parameters is set
correctly.
This
menu displays the X and Y dimensions of the platform, the distance from the top
of the platform to the transducer (Az), and the units of measure. The Az value can be found with the
calibration sheet included with your particular force platform. This information is automatically input from
the ANA file and should not require any changes.
5. Choose the CALIBRATE command from the
SETUP menu to specify the camera axis and Calibrate the 4 corners of the
plate.
The
user must first specify the location of the video camera in relation to the
force plate. This axis is relative to
the force platform coordinate system and represents the axis projecting from
the center of the platform to the camera.
Available selections are X, -X, Y and -Y. Then digitize the four corners of the plate as instructed. Digitizing begins with the Front-Left corner
of the plate and proceeds with Rear-Left, Rear-Right, and Front-Right corners.
6. Select the SYNCH, VIDEO commands
from the SETUP menu to specify the Synchronized frame of video. Select the Synch Video Frame using the
cursor and the left button of the mouse.
The video images will be displayed in the Synch Video Frame window. Selecting the buttons in the lower right
corner of the window can change the format of the display. Images can be advanced/reversed
one-at-a-time by selecting the +/- button.
Selecting the Next/Previous buttons will step advance by the number of
images currently displayed.
7. Select the SYNCH, ANALOG
commands from the SETUP menu to specify the Synchronized Time in the
analog (ANA) file. A dashed vertical
line will appear at the currently selected Synch Time. The Synch Time can be selected using the
left mouse button or by entering a numerical value. Selecting the ZOOM+ button will expand the displayed graph. ZOOM- will reduce the size of the graph. Selecting RESET ZOOM will restore the graph
to the original size.
At this point, the program
is ready to overlay Vectors on the video image.
CREATING OVERLAY VECTOR ON VIDEO IMAGE
Once the VECTOR file is
created and the Calibration and Synchronization process have been completed,
the program is ready to overlay Vectors on the Video image. This can be accomplished using the commands
in the IMAGES menu. The various
standard VCR commands/icons are used to PLAY, PAUSE, REWIND,
FAST FORWARD and STEP the images. The LOCK command can be selected when
multiple windows are open. When the LOCK
command is active, the IMAGES command affects all open windows. If the command is not active, the IMAGES
commands only affect the active window.
The Status of a Vector
file can be displayed at any time. This
menu provides a quick check on the current state of the active file.
1. Select the STATUS command from the VIEW menu to
display the Vector Status window. The current
status for each piece of information required by the VECTOR program will be
displayed. This information includes
the path for the AVI and ANA file, status of the Plate Calibration, and the
SYNCH points for both the AVI and ANA files.
Any field that indicates “MISSING” requires the user to perform the
necessary step to complete the missing information before the Vector display
can be generated.
Once the VECTOR overlay
file has been created, the entire file can be saved as a project (*.VEC file)
for later use. The SAVE/SAVE AS
commands can be used to save all the information that is used to create the
overlay. This includes, camera viewing
axis, force platform calibration, analog and video synchronizing information as well as the associated analog
and video files. There are two options
for saving the Vector file:
1. Choose the SAVE command from the FILE
menu. This command will Save the
current information using a sequentially numbered default file name
(vector1.vec, vector2.vec etc.) and Save it to the current drive and
directory. The *.VEC extension will be
added automatically.
OR...
2. Select the SAVE AS commands from the FILE
menu. The Save As dialog box will
appear showing the current file name, directory, drive and file type. At this point, you can enter the desired
name for the VECTOR file. Please note
that the file must have the VEC extension.
VECTOR files can be
created and saved to retain the necessary information for displaying the Vector
overlay. Files can then be Restored at
a later time for comparison and/or analysis.
There are two methods to Restore a previously created Vector file:
1. Choose the OPEN command from the File
menu. The OPEN File
Dialog box will appear. Select the
desired drive, directory and *.VEC file and click the OK button.
OR...
2. Select the File Open icon from the VECTOR
Tool Bar. The OPEN File Dialog box will appear. Select the desired drive, directory and
*.VEC file and click the OK button.
Select the STATUS
command from the VIEW menu to determine the status of the active
file. If everything is complete, the
Vector overlay can now be performed using the commands from the IMAGES menu.
When multiple files are
open, it is often useful to LOCK the images together. This causes all IMAGE commands to affect all open windows. When multiple windows are not LOCKed together,
IMAGE commands only affect the active window.
CHANGING THE VECTOR COLOR
Depending on the color and
quality of the AVI image, the force vector superimposed on the image might be
difficult to see. Displaying the vector
in a different color can often enhance visibility of the vector. The color of the vector can be changed by
the following process:
1. Select the COLORS, VECTOR command from the OPTIONS
menu. You will be presented with a
color palette of the available colors.
The box around the color designates the currently selected color. Select the desired color with the left mouse
button. Press the OK button to save the
selected color choice. Select the
CANCEL button to abort this menu without saving the changes.
CHANGING VECTOR PARAMETERS
Depending on the relative
force applied to the force platform, the force vector superimposed on the image
might be difficult to see. Scaling the
size of the displayed vector can often enhance visibility of the vector. The relative size of the vector can be
changed by the following process:
1. Select the VECTOR command from the OPTIONS
menu.
You will be presented with the
Vector options menu. The relative size
of the displayed vector can be altered using the button on the scroll bar. Moving the button up will make the displayed
vector smaller, while moving the button down will increase the size of the
vector. If desired, you can also change
the size of the vector by entering a numerical value in the SIZE field.
The Vector Mode option is
selected to display the superimposed vector in a single, multiple or accumulate
mode. The current selection is
indicated to the left of the Single/Multiple/Accumulate option. Single will display a single vector
corresponding to the current image.
Multiple will display all the vectors for the current vector project. Accumulate sequentially displays the vector
with the current image while leaving the previous vectors displayed on the
screen.
The numerical data used to
compute the displayed force vector are displayed in the lower portion of the
VEC project window. This data
corresponds to the current image and is updated when the image is advanced or
reversed. The force platform data can
also be displayed in graphical format.
GRAPHING THE FORCE DATA
Depending on the
particular application, it may be useful to display the graphical data along
with the superimposed vector. The
graphical display of the force data can be created by the following process:
1. Select the Fxyz command from the GRAPH menu. The three component forces (X, Y and Z) will
be displayed vs time.
GRAPHING THE MOMENT DATA
The Mxyz command is
selected to graph force platform moments about the axes of the platform. The X-moment displays the moment about the
x-axis of the force platform, the Y-moment displays the moment about the y-axis
of the platform and the Z-moment displays the moment about the z-axis of the
platform.
1.
Select the Mxyz
command from the GRAPH menu. The
three component moments (X, Y and Z) will be displayed vs time.
GRAPHING THE Ax/Ay DATA
The Axy command is
selected to graph the location of the point of force application on the
platform in Cartesian coordinates. Ax
is the x-component of the point of force application and Ay is the y-component
of the point of force application.
1. Select the Axy command from the GRAPH menu. The X and Y components of the force will be
displayed vs time.
GRAPHING THE COP LOCATION
The Ax vs Ay
command is selected to graph the force platform vectors in the X-Y plane (as
viewed along the Z-axis of the force platform). The display shows the force platform in the X-Y plane and the
point of force application on the surface of the platform. ). This is often referred to as the
center-of-pressure (COP) plot.
1. Select the Ax vs Ay command from the GRAPH
menu. The three component forces (X, Y
and Z) will be displayed vs time.
A complete analysis often
requires data to be analyzed from different views. The Vectors program allows the ability to simultaneously display
various data windows to help provide the complete picture of the analysis. These data windows include graphs, 2D/3D
vector displays, video and worksheet options.
All data windows within a single project are automatically synchronized
and can be animated either forward or reverse.
A description of each of the display options is listed below
2D VECTORS
The 2D Vectors
command is selected to graph force platform vectors in both the X-Z and the Y-Z
planes (as viewed along the Y and X axes).
The graphs show the force platform in both the X-Z and Y-Z planes and
force vectors are drawn from the surface of the platform at the point of
application of the force. The length
and direction of each vector corresponds to the magnitude and direction of the
applied force at that point in time. Force
vectors are drawn at equal time intervals spanning the entire sampling period.
1. Select the 2D Vectors command from the DISPLAY
menu. Two graphs will be displayed
illustrating the force vectors in the X-Z and Y-Z planes
3D VECTORS
The 3D Vectors
command is selected to graph force platform vectors in 3-Dimensions. The display shows the force platform in 3-D
and force vectors are drawn from the surface of the platform at the point of
application of the force. The length
and direction of each vector corresponds to the magnitude and direction of the
applied force at that point in time.
Force vectors are drawn at equal time intervals spanning the entire
sampling period.
1. Select the 3D Vectors command from the DISPLAY
menu. Two graphs will be displayed
illustrating the force vectors in 3-Dimensional views.
SPREADSHEET
The Spreadsheet
command is selected to display the force plate data in numerical format. Eight columns of data include Fx, Fy, Fz,
Mx, My, Mz, Ax and Ay values for each time interval.
1. Select the SPREADSHEET command from the DISPLAY
menu. The numerical data used to generate
the force vectors will be displayed in a worksheet format.
The Vectors module
incorporates the ability to “zoom” the image for additional clarification.
1. Select the ZOOM command from the VIEW
menu. The displayed image can be set to
one of five zooming factors.
AUTO - Scales the displayed image
to fit in the open window.
Zoom 0.5x - Reduces the displayed
image to approximately one-half of the normal size.
Zoom 1.0x - Scales the displayed
image to normal size
Zoom 2x - Zooms the displayed
image to approximately twice the normal size.
Zoom 3x - Zooms the displayed
image to approximately three times the normal size
1. Select FILE, NEW (or the New Document icon in the
Tool Bar) to Open a new *.VEC document.
2. Select FILE, VIDEO FILE (or the
AVI icon in the Tool Bar) to open an associated Video (AVI) File.
3. Select FILE, ANALOG FILE (or the
ANA icon in the Tool Bar) to open an associated Analog (ANA) File.
4. Select SETUP, DIMENSIONS to make
certain the force platform parameters are set correctly.
5. Select SETUP, CALIBRATE to specify the
camera axis and Calibrate the 4 corners of the plate.
6. Select SETUP, SYNCH, VIDEO to
specify the Synchronized video image.
7. Select SETUP, SYNCH, ANALOG to
specify the Synchronized time in the analog (ANA) file.
8. Select IMAGES, PLAY FWD (or the Play
Forward icon in the Tool Bar) to start the vector overlay sequence.
9. Select FILE, SAVE AS to save the
Vector project.
10. Select FILE, EXIT to exit the VECTOR
program.
CHANGING
VECTOR PARAMETERS
1.* Select OPTIONS, COLORS to set the Color of the
displayed vector.
2. Select OPTIONS, VECTOR to set the
relative size of the vector and/or the vector mode.
3. Select FILE, SAVE to save the Vector
parameters with the *.VEC file.
Listed below are the various
menus for the VECTOR program. Select
the desired menu to see a description of the available commands for each menu.
FILE COMMAND MENU
