Notes from March 16 meeting

A short project meeting took place on March 16. In attendance were; Steven, Gene, Ellen, Ting, Dan, and Zach. Discussion centered on methods for providing directional feedback to deaf users of the WiiCane system and integration of the WiiCane and Optotrak systems for testing at WMU. Some brief notes on the discussion:

Gene recapped his headphone tests - two deaf users were unable to feel high- or low-frequency vibrations from the Sennheiser headphones. Gene indicated that he feels the headphone cushions dampen the vibration from the drivers and laid out a few options for making the vibrations felt including; attaching tinfoil to the drivers and removing the headphone cushions.

Dan suggested using two additional Wii Remotes on the user's body to provide additional channels of vibratory feedback. Agreement all around - we'll try this next.

There was further talk of the placement of the Wii remote and infrared illuminator on the cane. Main concerns here seem to be minimizing the effect of the additional weight on the user's cane-handling, and ensuring the placement of the remote doesn't interfere with the user's normal grip. Ellen and Gene gave some direction and Steven will fabricate an adjustable mount to evaluate placement.

We closed with a short discussion about running the WiiCane and Optotrak systems simultaneously. There is some concern that the WiiCane's infrared illuminator will interfere with the Optotrak's infrared-sensitive cameras or that the Optotrak's infrared-emitting markers will interfere with the WiiCane's sensor. Zach will followup with Rob to determine if both systems can be run simultaneously.

headphones testing

Headphone testing

Sennheiser TR/HDR 120, 22 Hz to 19,500 Hz

This is not a success story. I set up the headphones on a desktop at HKNC. The phones came with batteries and adapters for the plugs. Setup was easy. I could not save the sound file, but I was able to play it from the email. The controls for volume and forward/rewind appeared in the email. One feature of the phones I did not like was the “tune” slide-wheel needed to optimize the signal between the transmitter and the phones. If not set just right the signal was less than strong.

I set the phones and the computer volume on maximum; there was no frequency controls. I tested the phones with on deafblind subject and on deaf subject. Hearing loss was severe-profound to profound. Both subjects did not wear hear aids. Neither subject could feel the vibrations from the phones during several sound playback. I removed the pads from each ear phone, but neither could feel the vibration. I asked the subjects to place there hands on the phones, but neither could feel the vibrations.

Possible problems/solutions:

* It seems I could not get sufficient volume. Is it possible to create a file with significantly higher dB output? I would like to raise the volume and the lower frequencies.
* I plan to try ear buds. I have a pair from my iPod.
* A lighter or different phone material – which might reverberate better – might work.

There was literally no recognition from the subjects of any vibrations, even when focused on the task.

We might need to go to plan B for this. I am open to ideas and suggestions.

Wii Remote and IR Illuminator

I have finished the first round of tests with the infrared illuminator, Wii Remote, and retro-reflective materials. The results look good all around - using a simple IR flashlight with three LEDs emitting at 940 nm, the Remote's camera is able to track retroreflective samples at a distance of three feet or so.

There are a number of design improvements to make for the next round of testing including; increasing light output, increasing efficiency, and reducing weight of the package. This first unit is headed to Robert now for testing with his Optotrak system.

headphones

I met with Steve today at TG and we reviewed various parts of the project. We visited B&H and purchased wireless headphones, Sennheiser TR/HDR 120, 22 Hz to 19,500 Hz. I will be bringing them to HKNC and trying them an several deafblind students. If the headphones' output works and the deafblind folks can readily identify left/right, then I'd like to try this with the Wii system.

Steve and I also discussed the vibration-motor output on the Wii, which we want to use as an alternative for veering feedback (spoken feedback via headphones as the other system output).

Wii Remote IR sensitivity

One of the open questions about using the Wii Remote's infrared-sensitive camera has been which part of the infrared spectrum it was most sensitive to. Our plan to track retroreflective strips on the course will work best if we flood the scene with IR illumination in the right range.

There is no official word on the subject from Nintendo, but there is anecdotal evidence that the optimal wavelength is 940 nm.

I have tested IR illuminators at five different fixed wavelengths: 850, 870, 890, 940, and 950 nm. My results agree with those above - the Remote's camera seems to be most sensitive to illumination at 940 nm.

experimental design for K-zoo verification

An interesting discussion has been taking place between Zach and Rob regarding the best way to run the comparison between the WiiCane and the Optotrak systems that we have planned for early June. As everyone already knows, our project calls for running test subjects along a 30 foot straight line course using both systems.  both apparatus call for mounting IR light sources on the cane, and Zach and Rob think they might interfere with one another, which would significantly complicate matters. They also wonder whether it is necessary or important, from an experimental design perspective, to do them simultaneosly, so that we end up with head-to-head, swing-by-swing comparisons for individual running of the course by study participants.  I have always thought that they would be done separately, but I can see very good arguments for doing them together. We will be much more confident in the WiiCane system's accuracy if we can compare results collected simultaneously, because we will see, for each participant, whether the device is accurate or not, and if it is not, we will immediately know which aspects of our system need improvement. But if we do them separately, we will have to aggregate the results and try to draw conclusions, which is certainly possible, but will require more number crunching, and will inevitably be less directly meaningful. I think that Annette, as the Project Evaluator, should weigh in here.  Of course, we will not know if this is a problem until we actually try both systems in the presence of IR light sources.  I think we need to do this test right away, and certainly not wait until we are in K-zoo to do it.  It would be best if we could use a single IR source mounted on the cane that can work for both WiiCane and Optotrak.  Having two many devices and cables mounted to the cane and cables will affect weight and balance, and may have other unexpected consequences.