tactile displays
DESCRIPTION
Tactile Displays. Kaczmarek, K.A. and Bach-Y-Rita, P. (1995), Tactile displays, in Virtual Environments and Advanced Interface Design , Barfield and Furness, pp. 349-414. Summarized by Geb Thomas. Your 2m 2 of skin. 90% hairy, 10% glabrous (hairless) Accessible Richly innervated - PowerPoint PPT PresentationTRANSCRIPT
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Tactile Displays
Kaczmarek, K.A. and Bach-Y-Rita, P. (1995), Tactile displays, in Virtual Environments and
Advanced Interface Design, Barfield and Furness, pp. 349-414.
Summarized by Geb Thomas
![Page 2: Tactile Displays](https://reader035.vdocument.in/reader035/viewer/2022081505/56815405550346895dc1ffaf/html5/thumbnails/2.jpg)
Your 2m2 of skin
90% hairy, 10% glabrous (hairless) Accessible Richly innervated Precise discrimination Adaptable to spatial and temporal displays
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Covered Here
Present and potential applications
Mechanisms of normal touch perception
Technology for producing tactile displays
Practical considerations
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Traditional displays for the blind
Braille (6-dot matrix, 2.3mm separation,
125 words*min-1)
Sign language: finger spelling: 6 letters*
sec-1, American Sign Language: 4-5
syllables*sec-1)
Tadoma 3 syllables*sec-1
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Tactile Feedback from tactile sensors For people with poor haptic perception in their
hands (Hansen’s disease, suited astronauts) strain guages on a glove to forhead electrodes:
can detect shape and texture! Movable pins, enhanced fingerpads, tactile
pads, glove-hand adhesion, removable glove fingertip
Sample task: no feedback: 92s, force feedback 63s, barehanded: 14s
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Tactile auditory substitution
Auditory prosthesis which adjusts the perceived intensity of 16 electrodes, each corresponding to the sound intensity of a given passband in the audio spectrum.
Improve speech clarity for deaf children Improve auditory discrimination and
comprehension in older patients
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Tactile vision substitution (TVS)
Television Camera to users skin with a vibrotactile or electrotactile stimulators array.
Stimulation intensity is controlled by grayscale
Distal attribution -- with practice, user perceives the stimulation to be in front of them
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Tactile Reading
Optacon 6x24-row vibrating fingerpad 90 words*min-1 exceptional 28 words*min-1
normal Now discontinued Significant underground calling for its
resurgance
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Static tactile displays
64-solenoid, four level display presenting graphical information
Another model has one prime mover and many piezoelectric latches
Muscle wire display
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Virtual tactile tablet
Fingerpad vibrotactile stimulation array on a mouse
5x20 array of pin vibrotactors mounted directly above t-shaped mouse
Minsky’s sandpaper display
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Human Tactile Perception
Six types of cutaneous receptors, four functions– Fast adapting, broad receptive field (FAII) --
high-frequency vibration– Fast adapting, small receptive field (FAI) --
localized movement fine form and texture– Slow adapting, large-field (SAII) -- maybe not
involved in haptics– Slow adapting, small-field (SAI) -- form and
roughness
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Measures
Smallest amount of pressure Two-point limen (two point discrimination
threshold TPDT) Affected by location, practice, fatigue,
distraction Modeling attempts include convolving
integral, low-pass filter or Gaussian blur
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Design Criteria
Static tactile displays Vibrotactile displays Electrotactile displays
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Static
High power consumption Rapid adaptation to static stimuli 12-20mm height to match Optacon
accuracy
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Vibrotactile
Threshold: 5 micro-m at 25-650 Hz for small areas (<.05 cm2)
Adaptation to strong stimuli Full recovery requires 2 min. 160 Hz is best 10dB over threshold 1 mm diameter stimulator with .5mm
movement
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Electrotactile Displays
Current through skin Current-limited Balanced, biphasic pulses with zero net DC
current Electrodes to produce appropriate ions (gold,
platinum, silver) Electrode size is important Some are implantable
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Important Issues
Pain threshold Skin condition Sensory adaptation Subjective magnitude of electrotactile
stimulation