User guide

Getting started

  1. Connect both the DC power input and the USB cables.
  2. Run the fab command from the Terminal or Windows shell.

On running the fab command, a browser window will open containing the user interface for the FAB device, shown below.

The FAB user interface

The FAB user interface

The device has 3 primary modes of use:

  • Manual control
  • Programmed control
  • Calibration mode

fab command options

..code

--no-box        Allows the UI server to run without an FAB device connected,
                for testing or demos.

-v --verbose    Displays more verbose messages.

--port          Which port the UI server should run on. Defaults to 2008

Target weights and tracking

In both manual and programmed control, the interface distinguishes between:

  • Target value for the weight in grams to be applied to each hand.
  • The actual measurements recorded by the sensor [1].
[1]Note that the exact pressure applied to the finger will vary as a function of the probe size.

Targets can be set in ‘grams’ for each hand[#grams]_. Once a target has been set the control software moves the probes up and down, attempting to maintain the target weight, as measured by the sensor. Thus where participants flex or move their fingers, the system will attempt to compensate to keep the measured force constant.

Manual control

Using the slider controls under the ‘manual’ tab, you can set a target weight in grams for each hand.

Manual control interface

Programmed control

Program interface

Programs for blocks of stimuli can be entered in the text area. Programs are simple lists of comma-separated integers. The first column specifies the duration, the second the target in grams for the left hand, and the third the target for the right hand. So, the following lines:

20,500,500
10,1000,2000

Denote a program which will deliver 500g to both hands for 20 seconds, and then 1000g to the left and 2000g to the right hands for 10 seconds.

At the end of a program target weights are set to zero.

Adding prompts to programs:

In addition, programs can cause an audio prompt to play the word “left” or “right”. Simply add “left” or “right” as a 4th element to a line in a program:

::
5, 500, 500, left 10, 500, 500, right

Would play the words “left” and “right” at 5 and 10 seconds respectively.

Get set, Stop and Reset buttons.

  • The get set button sets the target for both hands to 20g. This allows a participant to find a comfortable position, and for program to begin from a common reference point.
  • The stop button will always stop any program or manual setting, and reduce the target weights to zero. Additionally, the probes will be moved approx 1mm upwards to give the participant space to move their fingers.
  • The reset button moves both probes to their top resting points.

Logging and data capture

By default, log files will be saved into ~/Documents/fab/logs/.

The current log file name can be changed (e.g. per-participant) in the ‘Detailed Log’ tab, next to the console.