These are normalized by the highest-amplitude FFT value found on any channel. The highly discrete nature of taps i. Inspection of the confusion matrices showed no systematic errors in the classification, with errors tending to be evenly distributed over the other digits. Appropriating the human body as an input device is appealing not only because we have roughly two square meters of external surface area, but also because much of it is easily accessible by our hands e. Thus, features are computed over the entire input window and do not capture any temporal dynamics. While we do not explicitly model the specific mechanisms of conduction, or depend on these mechanisms for our analysis, we do believe the success of our technique depends on the complex acoustic patterns that result from mixtures of these modalities.
To capture this acoustic information, we developed a wearable armband that is non- invasive and easily removable. Moving the sensor above the elbow reduced accuracy to While bone conduction microphones might seem a suitable choice for Skinput, these devices are typically engineered for capturing human voice, and filter out energy below the range of human speech whose lowest frequency is around 85Hz. This is unsurprising given the morphology of the arm, with a high degree of bilateral symmetry along the long axis. An average of these ratios 1 feature is also included. Subsequent feature selection established the all-pairs amplitude ratios and certain bands of the FFT to be the most predictive features.
It should be noted, however, that other, more sophisticated classification techniques and features could be employed. Some energy is radiated into the air as sound waves; this energy is not captured by the Skinput system. I am very grateful to Prof.
One option is skinptu opportunistically appropriate surface area from the environment for interactive purposes. For gross information, the average amplitude, standard deviation and total absolute energy of the waveforms in each channel 30 features is included.
A point FFT for all ten channels, although only the lower ten values are used representing the acoustic power skkinput 0Hz to Hzyields features. To further illustrate the utility of our approach, we conclude with several proof-of-concept applications we developed.
Thus, the results presented are to be considered a baseline. A full description of SVMs is beyond the scope of this paper. The audio stream was segmented into individual taps using an absolute exponential average resrarch all ten channels.
Skinput: appropriating the body as an input surface
This search revealed one plausible, although irregular, layout with high accuracy at six input locations. If start and end crossings were detected that satisfied these criteria, the acoustic data in that period soinput a 60ms buffer on either end was considered an input event. This effect was more prominent laterally than longitudinally. Skinput leverages the natural acoustic conduction papeg of the human body to provide an input system, and is thus related to previous work in the use of biological signals for computer input.
(DOC) SKINPUT TECHNOLOGY | Sai Dheeraj Reddy –
Furthermore, proprioception our sense of how our body is configured in three-dimensional space allows us to accurately interact with our bodies in an eyes-free manner. In contrast, brain signals have been harnessed as a direct input for use by paralyzed patients, but direct brain computer interfaces BCIs still lacks the bandwidth required for everyday computing tasks, and require levels of focus, training, and concentration that are incompatible with typical computer interaction.
Finally, our sensor design is relatively inexpensive and can be manufactured in a very small form factor e. Unlike in the five-fingers condition, there appeared to be shared acoustic traits that led to a higher likelihood of confusion with adjacent targets than distant ones.
Chris Harrison | Skinput
For example, the ATmega processor employed by the Arduino platform can sample analog readings at 77 kHz with no loss of precision, and could therefore provide the full sampling power required for Skinput 55 kHz total.
Researcj location thus provided slightly different acoustic coverage and information, helpful in disambiguating input location.
Additionally, the cantilevered sensors were naturally insensitive to forces parallel to the skin e. Remember me on this computer. Speech input is a logical choice for always- available input, but is limited in rresearch precision in unpredictable acoustic environments, and suffers from privacy and scalability issues in shared environments. Roughly speaking, higher frequencies propagate more readily through bone than through soft tissue, oh bone conduction carries energy over larger distances than soft tissue conduction.
These, however, are computationally expensive and error prone in mobile scenarios where, e. However, these transducers were engineered for very different applications than measuring acoustics transmitted through the human body. This is not surprising, as this condition placed the sensors closer to the input targets than the other conditions.
Bone conduction headphones send sound through the bones of the skull and jaw directly to the inner ear, bypassing transmission of sound through the air and outer ear, leaving an unobstructed path for environmental sounds.
The below- elbow placement performed the best, posting a We assess the capabilities, accuracy and limitations of our technique through a two-part, twenty-participant user study.
However, tables are not always present, and in a mobile context, users are unlikely to want to carry appropriated surfaces with them at this point, one might as well just have a larger device. Few external input devices can claim this accurate, eyes-free input characteristic and provide such a large interaction area. Appropriating the Body as an Input Surface Devices with significant computational power and capabilities can now be easily carried on our bodies. The eyes-free input condition yielded lower accuracies than other conditions, averaging In the paper linked below, we present our research on Skinput — a method that allows the body to be appropriated for finger input using a novel, non-invasive, wearable bio-acoustic sensor.
Inspection of the confusion matrices showed no systematic errors in the classification, with errors tending to be evenly distributed over the other digits.