Cooper Instruments & Systems ELF 4200 Flexiforce Paper Thin Sensor User Manual

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CF10

6/24/08 Rev. H

how the data is displayed on the screen. Any changes made to the Properties will only affect the currently
active Real-time or Movie window. The Properties dialog box will also appear whenever you click the right
mouse button over a Real-Time or Movie Window. You can select a display option ("Strip Chart", "Column" or
"Number"), and also change the "Scale Max", "Scale Min", and "Units".

Real-Time Window:

A Real-time Window displays the load applied to the sensor as it is happening (in Real-time).

The Properties of this display can be changed in the File pull-down menu, or by clicking the right mouse button.

Recording Parameters:

The recording parameters act as settings for your Movie. Before you record a movie, you

should access the Recording Parameters dialog box by going into Record -> Settings. Within this dialog box
you can select what type of recording you are going to create. Things that can be selected are the amount of
frames, speed of recording, any triggering options that need to occur before the recording starts, Which sensor
will trigger the recording, and the type of units (Pounds, Newtons, Kilograms, etc.).

Repeatability:

Repeatability is the ability of the sensor to respond in the same way to a repeatedly applied force.

As with most measurement devices, it is customary to exercise, or .condition. a sensor before calibrating it or
using it for measurement. This is done to reduce the amount of change in the sensor response due to repeated
loading and unloading. FlexiForce sensors are generally repeatable within 2.5% once they have been
conditioned. A sensor is conditioned by loading it to 110% of the test weight four or five times.

Saturation:

The saturation force is the point at which the device output no longer varies with applied force. The

saturation force of each sensor is based on the maximum recommended force specified by Tekscan, which is
printed on the system packaging or the actual sensor, along with the sensitivity. Sensors are available in three
force ranges (Low, Medium, and High), which have specified maximum forces of 25, 150, and 1000 lbf,
respectively. The sensor.s effective force range (up to the specified maximum) can be altered by adjusting the
system sensitivity. Decreasing the sensitivity setting (1 to 20 possible) will increase the force range (displayed
as .Approx Max Range.), and saturation force, of the sensor, and vice versa. It is essential that the sensors do
not become saturated during testing. See "Sensitivity" and "Calibration".

Save As (File Menu):

The "Save As" command will save the current movie with the specific file name and location

of your choice. ELF movie files must have the extension *.flf. Note that your system may limit filenames to eight
characters. This menu item can be used to save a movie file under more than one filename.

Save as ASCII (File Menu):

The "Save As ASCII" command saves the current Movie frame as an ASCII file, with

the extension *.csv. Since these files are in ASCII (comma separated value) format, they can be imported into a
spreadsheet program (e.g. MS Excel), or they can be opened in a text editor or word processing program (e.g.
MS Word) in order to review and manipulate the data.

Save Calibration (Tools Menu):

The "Save Calibration" command allows you to save your current calibration as a

file for future use. When this item is selected, a ‘Save As’ dialog box appears, and the calibration file can be
saved with the specific file name and location of your choice. Calibration files must have the extension *.clb,
and can contain up to eight characters. The Sensitivity setting is also saved by the calibration file.

Scroll Bar (Movie Window):

The Scroll bar is located directly above the status bar in a Movie Window (at the

bottom of the movie window below the force data). It can be used to move to any point (frame) in the movie.

Select Colors (Tools Menu):

The "Select Colors" command allows you to customize the background color, as well

as the trace color for each ELF device in your View windows. When this item is selected, the ‘Select Graph
Colors’ dialog box appears. By clicking on either Trace Color or Background Color, a Windows color palette
becomes available, and you can select one of the standard colors or create your own custom color for each of
the COM ports (sensors). The color you choose will be used for all Movie and Real-time windows, and will be
set as the default color. To restore the original color, select the Default All Colors button.

Sensing Area:

The Sensing area is the silver circle located on the top of the sensor.

Sensitivity:

Also referred to as "Adjustable Gain". This adjustment sets the data output range from the computer (0

to 100%) to the actual force range output from the system handle. In this way, the usable force range of the
sensor can be adjusted (up to the rated maximum force). Sensitivity settings are saved between sessions, and
are included with calibration files. Sensitivity can be accessed directly from the Tools Menu or from within the
Calibration dialog box.

Sensor Life / Durability:

Sensor life depends on the application in which it is used. Sensors are reusable, unless

used in applications in which they are subjected to severe conditions, such as against sharp edges, or shear
forces. FlexiForce sensors have been successfully tested at over one million load cycles using a 50 lb. force.
Rough handling of a sensor will also shorten its useful life. For example, a sensor that is repeatedly installed in
a flanged joint will have a shorter life than a sensor installed in the same joint once and used to monitor loads