Pretentation finished

master
mDescape 2 years ago
parent 875682ed06
commit c96801418b
  1. BIN
      Documents/Presentació_TFG_29-Juny.pptx
  2. 58
      Documents/Presentació_TFG_29-Juny_guió.txt
  3. BIN
      Documents/Technical_report_Descalzo.docx
  4. BIN
      Documents/~$chnical_report_Descalzo.docx

@ -27,21 +27,22 @@ The restrictions on the system have been basically two:
- It should be at least as good as the systems used in the previous studies.
- and It must not be able to induce any type of injury to the participants.
This means, the system needs a light source able to emit enough intensity, it should create accurate stimuli, and it
might need to incorporate precautions to prevent the creation of hazardous stimuli, among other things.
might need to incorporate precautions to prevent the creation of hazardous stimuli.
(PASAR DIAPOSITIVA)
In regards of the chosen solution for the system, I'd like to highlight the following aspects.
When presenting the stimuli to the participants, it is important to do it in a known and controlled manner.
This system is using the Single Interval Adjustment Matrix method (or SIAM method) to choose which stimulus will be
presented next. The SIAM method is a psycophysichs adaptative method of presenting stimuli for estimating absolute
thresholds, which means the next presented stimulus will depend on the previous answers given by the participant.
There are other methods of presenting stimuli which could be implemented.
The stimuli presented are not randomly choosen, they are presented one ofter one according to a known phsychophysics
method. This system is using the SIAM method to choose which stimulus will be presented next. The SIAM method is what
is called an "adaptative method", which means the next presented stimulus will depend on the previous answers given
by the participant. There are other methods of presenting stimuli which could be implemented, but for now this is
the only method programmed whithing the system.
As a light soruce the system uses a video projector. The used device is clasified in the Risk Group 2, which
according to the european standard of photobiological safety of lamps and lamp systems it does not pose any hazard
to human vision when exposed to its light beam for 0.25s or less.
As a light soruce the system uses a video projector. The used device is clasified in the Risk Group 2,
according to the european standard of photobiological safety of lamps and lamp systems, which means it does not pose
any hazard to human vision when exposed to its light beam for 0.25s or less.
To accurately measure the time the stimuli are on screen, the system uses a light sensor and a microcontroller
which comunicates to the main program if the last stimulus was presented for longer than 0.25s or not. If a
@ -49,7 +50,7 @@ hazardous stimulus is detected, the test finishes itself up in order to prevent
In order to calibrate the stimuli generated, the system uses a spectrometer to read the light intensity which will
be received by the participants. Using the spectrometer, a transfer function from the stimuli generator function the
the illuminance received is found automatically using a calibration script. With such transfer function the system
the illuminance received is found using a calibration script. With such transfer function the system
then generates the needed stimuli for the test.
(PASAR DIAPOSITIVA)
@ -63,7 +64,7 @@ the system parts. The spectrometer, the light sensor and the projector.
In this slide I'll give a brief explanation of the characteristics of each system's component. This is the
implementation made for the solution presented on the last slides.
About the stimuli generated by the system, they are a plain white image, of diferent intensities projected for less
About the stimuli generated by the system, they are a white image, of diferent intensities projected for less
than 0.25s.
The spectrometer takes measures in an automatized maner. It is controlled by a Visual Basic program which also
@ -73,8 +74,8 @@ runing the main program could easily be separated by some distance, giving the s
The light sensor has actally two parts, the light sensor itself and a microcontroller, which digitalizes the
sensor's output, measures the time past between the start of each stimulus and the end of it, and send an order
to finish the experiment in case a stimulus is detected to be on screen more than 220ms, in order to prevent retinal
injuries.
to finish the experiment in case a stimulus is detected to be on screen more than two hundred and twenty ms, in
order to prevent retinal injuries.
(PASAR DIAPOSITIVA)
@ -90,7 +91,7 @@ a hazardous stimulus is detected, in order to prevent retinal damage.
(PASAR DIAPOSITIVA)
The stimuli generated by the projector are not static, they are associated whith an aleatory error which make its
illuminance change over time. In the worst case scenario caputred, the standard derivation of a stimulus is of only
illuminance change over time. In the worst case scenario caputred, the standard derivation of a stimulus was of only
6.3%, which is provably small enough to not be detected by the human eye.
When the system is calibrated, after 12h it keeps producing the desired stimuli precisely, within the same error
@ -101,7 +102,7 @@ to detectd when a stimulus is on screen or not, the light sensor needs to averag
average is above 0.25V it interprets the stimulus is on screen and when it falls under 0.25V again, it interprets
it has finished.
In order to give the participants the instructions on how to perform the test, a screen is shown before the test
In order to give the participants the instructions on how to perform the test, a screen is shown before it starts
starts where the instructions can be read.
(PASAR DIAPOSITIVA)
@ -123,3 +124,30 @@ first section of the calibration curve has a negligible aleatory error.
(PASAR DIAPOSITIVA)
The technical feasibility of the system is proven, since it's development is finished and it is functional.
Aditional improvements could be done if new needs arise, but for now the software it's finished.
If the Vall d'Hebton Research Institute would replicate the system, all they would need is to acquaire the hardware
specified in the technical report.
The total price of the hardware is 2 Thousand 7 hundred and 46 €. But some cheaper alternatives for the spectrometer
and the projector could be found, which are the pricier devices of the system. Lowering the total cost of the system.
(PASAR DIAPOSITIVA)
Now, going back to the system's objectives. They are mainly archeived. The experiment will start in the following
weeks and then it will be seen if the system needs any improvement.
We wanted a system able to produce at least 23 thousand lux and it can generate a illuminance of over 35 thousand
lux at 50cm of distance.
The system has a minimum sensibility of 0.6 lx/step but in most of its range it has a sensibility of around 140
lx/step. While other studies have used smaller sensibilities, this machine should be precise enough to determine the
discomfort perception threshold of the participants.
And, according to the results, there is no need for calibrating the machine more than once per day, and maybe even
less often.
As previously said, since the projector is classified as an RG-2 device, while the stimuli generated are on screen
for less than 0.25s, the injuries should be prevented. The system ensures hazardous stimuli are not being generated
by measuring the time the stimuli are on screen and finishing the test if a stimuli is presented for too long.
(PASAR DIAPOSITIVA)
This is everything I have to present now. Thank you for listening.
Do you have any questions?

Loading…
Cancel
Save