Ariel Dynamics, Inc.

ANALOG MODULE

Revision 1.0

Contents

ARIEL ANALOG PROGRAM                                                                                             

INTRODUCTION......................................................................................................................................

WHAT’S NEW IN ANALOG 1.0...........................................................................................................

SYSTEM REQUIREMENTS....................................................................................................................

TO START THE ANALOG PROGRAM...............................................................................................

SCREEN LAYOUT....................................................................................................................................

THE APAS TOOL BAR...........................................................................................................

THE TOOL BAR.......................................................................................................................

THE STATUS BAR..................................................................................................................

THE PARAMETERS BAR......................................................................................................

CREATING A NEW ANALOG FILE.....................................................................................................

CREATING AN EMG FILE (EXAMPLE)..............................................................................

CREATING A FORCE PLATFORM FILE (EXAMPLE)......................................................

ANALOG MEASUREMENT PROCESS................................................................................................

OPTIONS...................................................................................................................................................

SYSTEM OPTIONS..................................................................................................................

CHANNELS.............................................................................................................................

PLATES....................................................................................................................................

REAL TIME CENTER-OF-PRESSURE (COP).....................................................................................

ANALOG DATA DISPLAY..................................................................................................................

PLOT LIST...............................................................................................................................

NEW GRAPH..........................................................................................................................

ADD GRAPH...........................................................................................................................

TOOLS FOR GRAPHIC DISPLAY.......................................................................................................

FORCE PLATE DISPLAYS...................................................................................................................

EXPORTING ANALOG DATA............................................................................................................

ANALOG SIGNALS AND CHANNEL DEFINITION........................................................................

ANALOG QUICK REFERENCE............................................................................................................

ANALOG MENUS..................................................................................................................................

FILE COMMAND MENU.....................................................................................................

EDIT COMMAND MENU....................................................................................................

VIEW COMMAND MENU...................................................................................................

SAMPLE COMMAND MENU.............................................................................................

GRAPH COMMAND MENU................................................................................................

DISPLAYS COMMAND MENU..........................................................................................

EXPORT COMMAND MENU..............................................................................................

OPTIONS COMMAND MENU............................................................................................

TOOLS COMMAND MENU................................................................................................

WINDOW COMMAND MENU...........................................................................................

HELP COMMAND MENU....................................................................................................

 


ARIEL ANALOG PROGRAM

 

INTRODUCTION

The ARIEL ANALOG software is used as a general purpose laboratory data measurement and analysis sub-system.  The module is designed to sample, save and present analog signals from many independent channels.  A fast measurement rate is possible, with high resolution and programmable input voltage ranges.  Data signals are measured to a 12 bit (1 in 4096) resolution.  A number of triggering options are provided to assist in the capture of transient data and to allow the synchronization of the analog module with external events.  The analog module also includes a set of specialized electromyogram (EMG) signal processing options.  EMG data samples can be analyzed using a number of sophisticated techniques including spike analysis, signal rectification and integration, envelope processing and spectral analysis.

 

 

 

WHAT’S NEW IN ANALOG 1.0

A few of the new features you will see in ANALOG version 1.0

1.     High Sampling Rates.  Data can be sampled at rates up to 330 kHz.

2.     APAS Tool Bar.  A toolbar has been added to allow the user to activate individual APAS modules from within the main programs.

3.     Real-Time COP.  Software support for real time center-of-pressure using a force platform has been added.

4.     Vectors Display.  The Ariel Vectors program has been integrated into the program.

 

 

 

SYSTEM REQUIREMENTS

The following table provides the basic guidelines for minimum and recommended hardware to provide the best possible performance.  The software requires a minimum of Microsoft Windows 95/98 and APAS-2000 Revision 2.1 or later.

 

Component                         Minimum                                               Recommended

_____________________________________________________________________________________________________________________________________________________

 

Pentium Computer            Pentium 233                                         Pentium II 333 MHz or higher

RAM                                      32 MB                                                     64 MB or more

Analog Board                      CES#3 (Retrieve Only)                       Industry Standard A/D


TO START THE ANALOG PROGRAM

1.  Double-click the ANALOG icon located in the APAS System window group.  The main ANALOG window will appear.

 

 

 

SCREEN LAYOUT

Prior to performing the ANALOG module, 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 ANALOG program tool bar.  The tool bar is located near the top of the window.  The icons in the Analog Tool Bar can be divided into three sections.  Icons are pictorial representations of commands or functions.  You can access the following commands by clicking the appropriate icon.

MAIN ANALOG TOOL BAR

     The Main Tool Bar icons can be used to activate general file commands.

 

 

SAMPLE/RETRIEVE TOOL BAR

     The icons in the Sample/Retrieve tool bar will change depending on the current file MODE.  The Tool Bar for the A/D mode is shown on the left while the Tool Bar for the FILE mode is displayed on the right.

 

GRAPHING TOOL BAR

     Sampled data can be displayed using the icons in the Graphing Tool Bar.

 

THE STATUS BAR

The status bar provides useful information about the current status of the file during the Analog process.  The status bar is located at the bottom of the Analog window.  The far-right side of the status bar is divided into three separate fields. The left field indicates the make (if any) of the force platform.  The ANALOG MODE field indicates the current mode.  The A/D mode is used for data sampling while the FILE mode is used for retrieving previously saved data.  The third field is the TRIAL INDICATOR.  The first number indicates the current data trial within the analog file while the second number indicates the total number of saved data trials.

 

 

THE PARAMETERS BAR

You can specify most analog functions by selecting the desired option located on the ANALOG Parameter bar.

 

 

Last Channel - The Last A/D field is used to select the number of active analog channels.  Since the active channels always begin with channel A, the number of channels is set by specifying the last active channel.  The active analog channels appear in the channel table in the main Analog window.  The number of entries in this table are determined by the value of the Last A/D channel.  One should not specify more channels than the actual number of analog input signals, as any additional empty channels will waste input buffer space and possibly cause the sampling rate to be reduced.

 

Trigger Channel - The Trigger Channel is used to select the channel used for triggering.  It may be any of the active analog channels shown in the Channel Table.  The current trigger channel is displayed in the Analog Parameters Bar.

 

Period - The Period is selected to set the duration of analog measurement.  The sampling period is the length of an analog sample in seconds.  All the active analog channels are measured continuously over the sampling period.  The number of analog measurements that are performed for each channel during the sampling period is determined by the sampling rate or Rate/Chan.  The sampling rate is the number of data measurements per second for each analog channel.  The total number of data values sampled and saved is the sampling period times the rate/channel times the number of channels.  Thus, if 1000 is entered in Rate/Chan and 2 is entered as the Period, then 2000 data values are collected for each channel during the sampling period.  If there are eight active channels, then a total of 16,000 data values would be collected each time analog sampling is performed.

 

Rate/Channel - The Rate/Chan is used to set the sampling rate for analog data collection.  All active channels are sampled at the specified rate.

 

Trigger Level - The Level is used to set the signal level on that channel that will cause triggering.  The trigger level is entered in the units defined for that channel.  Since analog input signals may be positive or negative, this value may also be positive or negative.  Triggering will occur at the first measurement on this channel that is at or above the trigger level.  Thus the trigger is not used to start actual sampling, but rather to determine when the period of saved sample values is to start.

 

Pre-Trigger % - The Pre-Trigger% is used to select the percent of the total sampling period that will occur before the triggering event.  Pretriggering is accomplished by continuously sampling and saving data values in a circular buffer.  That is, only a limited number of samples are waved with new samples replacing the oldest ones.  This parameter can be set to any value between) (no pretrigger) and 99.  It is possible that less than the desired number of pretrigger samples may be collected.  This occurs when the triggering event is detected after analog input is armed or started, but before the full pretrigger period has elapsed.  In this event, the sampling period will be shortened by the amount that the pretrigger period is shortened.  The pretrigger option allows the trigger level to be set high enough to eliminate false triggering due to noise, while still capturing significant data signals that occur before the trigger.

 

CREATING A NEW ANALOG FILE

Unless analog measurements are to be immediately processed and then discarded, they must be saved in data files on the computer.  Data files can be created using the following procedure. 

1.  Choose the NEW command from the FILE menu.  The OPEN File Dialog box will appear.

The OPEN File Dialog box looks for a particular type of file (files that have the extension of (*.ANA).  The OPEN File Dialog box can be used to specify the Drive, Directory, and Name of the sequence file to be created. 

2.    Analog input is controlled by the analog sampling parameters that are displayed in the Parameter Bar.  These parameters must be set before the Analog Module may process the analog measurements.  Please refer to the Parameter Bar section for additional information.  Specify the following parameters to match the data collection requirements:
            Last Channel (LastCh)
            Trigger Channel (TrigCh)
             Period
            Sample Rate (Rate/Ch)
            Trigger Level (TrigLev)
            Pre-Trigger Percent (PreTrig%)

3.    Select the CHANNELS command from the OPTIONS menu to specify the Channel Information for the active analog channels.  The Channels command is used to set or change the individual analog channel definitions in the analog channel table. 

Any channel description (name), units, conversion factor (units/volt of analog signal), and offset (signal level in volts corresponding to zero in the units of that channel) may be entered.  The current channel settings are saved each time the analog module is exited so they do not have to be reset the next time the module is run.

4.    Select the PLATES command from the OPTIONS menu to activate/de-activate the force plate software.  The Plate command is used to define special force platform (force plate) processing by assigning a block of analog input channels to predefine force platform signals.  Typical biomechanical force platforms have six to eight analog outputs representing forces and moments measured directly by the platform.  These outputs are frequently combined or used to compute additional quantities such as composite forces, moments, and point of application of force.  Rather than require a user to set up numerous input channels, the Plate command automatically defines a consecutive group of channels as standard force platform input for the type of platform configured with this system (various platform definitions supporting most commercially available force platforms can be configured when the system is ordered).  In addition, since the channel definitions are predefined, the computed quantities are also automatically defined and displayed as additional analog channels.

5.    Set the desired channels on Plot Lists 1 through 3 by clicking in the desired column.

6.    You are now ready to sample the analog data

 

CREATING AN EMG FILE (EXAMPLE)

This example illustrates the procedure for creating a two-channel EMG file using electrodes with a gain of 1000.

1.   Select FILE, NEW to create a new *.ANA file.

2.   Use the Parameter Bar to set the following parameters:

      Last Channel (LastCh):  B1 (Two channels will be sampled)
            Trigger Channel (TrigCh):           A1
            Period:                                     5 seconds
            Sample Rate (Rate/Ch):             1000 samples/sec/chan
            Trigger Level (TrigLev):              0.2 mv
            Pre-Trigger Percent (PreTrig%):  10%

3.   Select OPTIONS, CHANNELS to specify the Channel Information for the active analog channels.

      Channel A:

                  Description:       Channel 1
      Units:                      mv
      Units/volt:    1  (Since gain=1000 and 1000mv=1volt)   Offset:               0  Calculated during the ZERO process

 

      Channel B:

                  Description:       Channel 2
      Units:                      mv
      Units/volt:    1
      Offset:                     0

 

4.   Select OPTIONS, PLATES and select NONE to de-activate the force plate software.

5.   Set the desired channels on Plot Lists 1 through 3 by clicking in the desired column.

      Click in the 1st column for Channel A1 and 2nd column for Channel B1.

6.   You are now ready to sample the analog data.

CREATING A FORCE PLATFORM FILE (EXAMPLE)

This example illustrates the procedure for creating an analog file for a single AMTI force platform (Gain = 2000 and Excitation voltage = 5)

1.   Select FILE, NEW to create a new *.ANA file.

2.   Use the Parameter Bar to set the following parameters:

      Last Channel (LastCh):              F1 (6 channels total)
Trigger Channel (TrigCh):                       C1 (Vertical force channel)
Period:                                     5 seconds
Sample Rate (Rate/Ch):             1000 samples/second/channel
Trigger Level (TrigLev):              10 lbs
Pre-Trigger Percent (PreTrig%):  10%

3.   Select OPTIONS, CHANNELS to specify the Channel Information for the active analog channels.

4.   Select OPTIONS, PLATES, AMTI to activate the software drivers for the AMTI force platform.

      Select the INFO tab and enter the following:

                  Length Units:                 Inches
      Force Units:                        Lbs
      #Plates:                              One
      1st Plate Channel:   A1

      Select the PLATE#1 tab and enter the following:

                  Transducer Depth:          1.36
      Length:                               20.00
      Width:                                 18.25

      Select the CAL#1 tab and enter the following:

                  Force Plate Constants:               FX = 2.883 uV/Vo/Lb
                                                FY = 2.864
                                                FZ = 0.725

                  Moment Calibration Constants:   MX = 1.770 uV/Vo/ft-lb
                                                MY = 1.770
                                                MZ = 3.423

      Select the ELECTRONICS tab and enter the following:

                  Excitation:                                 5.00 Volts                     Gain:                            2000

5.  Select OK to Calculate Plate Conversion Factors.  This will automatically update the Units/Volt entry in the Channel Information Table.

6.  Set the desired channels on Plot Lists 1 through 3 by clicking in the desired column.

      Click in the 1st column for Channel C1 (Z direction force)

      Click in the 2nd column for Channels A1 and B1 (X and Y direction Forces)

      Click in the 3rd column for Channels D1, E1 and F1 (X, Y, Z Moments)

7.  You are now ready to sample the analog data.

 

 

ANALOG MEASUREMENT PROCESS

Once the analog sampling parameters have been set to accommodate the signals being measured, actual analog sampling may begin.  The most recent values of the sampling parameters are saved and are reset when the module is run again.  Thus sampling parameters do not need to be set each time analog processing is begun unless sampling values must be changed.

 

1.  Choose the START command from the SAMPLE menu (or select the GO icon from the tool bar) to initiate Analog sampling.  When Start is selected, the analog module displays a reminder message to prepare for analog measurement. 

At this point actual sampling has not begun and three options are available.  The first option is to begin analog sampling by selecting the OK button.  The second option is to abort by selecting the Cancel button to return to the main Analog window.  The purpose of this additional step is to allow a final check of the analog signal source, force platform. EMG equipment, etc., and make sure that the subject is prepared to perform the activity being measured.  The third option is to zero any voltage offsets on the active analog channels.

2.   Select the ZERO button to compute the offsets for the active analog channels.

3.   Select the OK button to begin the sampling process.  As soon as analog input is "armed," the analog module begins measuring each of the input signals and monitoring the trigger channel for the triggering event.  A message will appear on the screen to indicate that analog sampling is in progress. 

Sampling may be aborted at this time by selecting the Cancel button.  The Cancel option is provided in the event the subject is not able to perform the activity, equipment malfunction, or there is an interruption in the normal sampling process.  Selecting Cancel will return the screen to the main Analog window.

Assuming that sampling has occurred normally and that the triggering event has been detected, analog sampling will end when all of the post trigger measurements have been collected.  The Analog Module will sound an audible "beep" to mark the end of data collection and the active analog signals in Plot List #1 will appear on the color graphic display.  The display is in graph format with the horizontal axis corresponding to the sampling period (time), and the vertical axis corresponding to the units of measurement of the analog signals.  The signal from each channel is displayed as a curve with different colors being used to distinguish different channels.

After sampling has been completed the graphed data is displayed in the Analog window.  This is the primary menu used for the display and analysis of data in the Analog Module.  Some of the listed options are used to display analog data measurements in different ways, while other options provide various types of data analysis  functions from simple measurement of values and intervals to sophisticated signal processing.  Included in these analysis functions are a number of specialized EMG processing applications.  A discussion of these display and analysis options will be the subject of the following sub-sections.

4.   Select FILE, EXIT to exit the ANALOG program.

 

 

 

OPTIONS

The ARIEL ANALOG software contains many options designed to enhance the analog process.  Selecting the OPTIONS menu accesses these options.  Available options allow for selecting the setting system parameters, specifying channel information and specifying force platform parameters. 

 

SYSTEM OPTIONS

 

The System command is selected from the OPTIONS menu when the default program mode or autoload option are to be changed.  When this command is selected, the System Options menu will be displayed indicating the current program mode and autoload option when opening an analog file.

PROGRAM MODE

The System Options menu is used to set the default program mode when opening a file.  The A/D mode is used for measuring and saving analog data values.  It is called A/D mode because actual analog-to-digital conversion is performed.

In the File mode, analog sampling cannot be performed using the analog-to-digital interface.  This option allows previously sampled and saved data to be read or retrieved from a data file.  In the File mode, one may advance to the next saved sample in the file or backup to the previous saved sample.  When a sample is read, the information is displayed in the same manner as when analog sampling has been performed.

It is possible to change between A/D mode and File mode at any time using the icons in the Analog Sample/Retrieve Tool Bar.  (NOTE:  Changing the mode using the Tool Bar does not affect the default setting.)  For example, if data is being sampled and saved in a file, the A/D mode, it is possible to review previous samples by selecting FILE mode and reading the desired sample.  Similarly, if previously sampled data is being examined, in the FILE mode, it is possible to add new data to this file by selecting A/D mode and performing additional sampling of analog signals.  New data is always saved at the end of a file so that previously saved data is retained.

 

AUTOLOAD 1ST SAVE

 

The System Options menu can also be used to set the auto-load option.  When this option is activated (YES), the channels listed in Plot List #1 of the first trial in the analog file will automatically be graphed.  If this option is inactive (NO), no data will be plotted.

 

CHANNELS

The Channels command is used to set or change the individual analog channel definitions in the analog channel table.  When this option is selected, the Misc. Options menu is displayed. 

Any channel description (name), units, conversion factor (units/volt of analog signal), and offset (signal level in volts corresponding to zero in the units of that channel) may be entered.  The current channel settings are saved each time the analog module is exited so they do not have to be reset the next time the module is run.  In addition, each time an existing analog data file is accessed, the channel definitions are copied from that file.  In this manner, different sets of channel definitions corresponding to different types of input (force platforms, EMG equipment, etc.) can be quickly accessed from a predefined data set.

 

The rest of this option discussion has been deferred to the section on Analog Sampling And Channel Definition, to allow the specific features of the analog module to be presented without having to be concerned with the actual source of the analog signals.  In practice, the first item to be considered in the data collection process is the source, type, and magnitude of the individual analog signals along with the corresponding definition of the analog channel table.

PLATES

The Plate command is used to define special force platform (force plate) processing by assigning a block of analog input channels to predefined force platform signals.  When this option is selected, the Plate Information menu is displayed.  Typical biomechanical force platforms have six to eight analog outputs representing forces and moments measured directly by the platform.  These outputs are frequently combined or used to compute additional quantities such as composite forces, moments, and point of application of force.  Rather than require a user to set up numerous input channels, the Plate option automatically defines a consecutive group of channels as standard force platform input for the type of platform specified.  In addition, since the channel definitions are predefined, the computed quantities are also automatically defined and displayed as additional analog channels.

When Plate is selected, the Plate Information menu will be displayed.  The information required by the software depends upon the make of force platform selected.  The AMTI plate has been used for this discussion.  Select each of the following tabs to enter the required information. 

 

The Info tab is selected to specify the desired units for length and force, the number of plates being used and the first platform channel.  The units selected for length and force will be used for reporting data results and can be changed at any time.  Outputs from the force platform must be connected sequentially therefore, only the first channel must be specified.  The analog module will then show the expected force plate inputs and channel assignments for the type of plate configured to the system.  Once configured, all measured and computed force plate quantities are available for graphing and analysis.

The Plate #1 tab is selected to enter dimensions for the first force platform.  The Transducer Depth is obtained from the force platform calibration information and is equal to the vertical distance from the top of the force platform to the top of the transducer.  The Length and Width are also obtained from the force platform manual.  All Dimension values must be entered in the user specified units.

The Plate #2 tab is selected to enter dimensions for the second force platform as well as the orientation of the first force platform to the second force platform. 

Refer to the following diagram for the orientation of two force platforms.

Required information for two force platforms includes:

Translation from Origin on both the X and Y directions

Rotation Angle - Measured Counter-Clockwise, this number represents the angle from force platform #1 to platform #2.

 

The CAL #1 and #2 tabs are selected to enter the Force and Moment Calibration Constants.  These values are obtained from the calibration values supplied in the force platform documentation.

Electronics is selected to enter the force plate amplifier information.  The required information is dependent upon the type of force plate being used.  This information can be obtained by reading the current settings on the force plate amplifier hardware.

 

REAL TIME CENTER-OF-PRESSURE (COP)

The Real Time Center-of-Pressure (COP) mode provides a method to measure and analyze balance and stability parameters.  This type of analysis can be used for testing the effects of orthotics and prosthetics, evaluating sports performance requiring stability, and examining orthopedic or neurologic dysfunction.  Suggested steps for using the COP option are listed below.

1.    Configure force plate setup as described in the section titled Creating A Force Platform File.

 

2.    Select the COP command from the SAMPLE menu (or the COP icon in th