Tactile Stimulation is both a method of Communication
and Controlled Sensation. Common methods of tactile inputs are vibration,
electrostimulation, and temperature. Our R+D efforts are primarily
focused on VibroTactile and ElectroTactile Stimulation. The many
dynamic applications of tactile stimulation include Spatial Orientation,
Navigation, Obstacle Homing / Avoidance / Evasion, Alternate Communications,
and Sensation Feedback. Tactile Mapping is useful in areas where
normal visual/auditory channels are saturated, obstructed, impaired or
may cause undesired effects.
ETS Theory of Operation
ElectroTactile Stimulation (ETS) uses surface
electrical signals to affect directly the nerves related to perception.
The control of muscles and the sensations perceived by nerves are accomplished
with small bioelectric signals. Surface contacts (or tactors) provide
a point to point and point to multi-point mechanism to create crisp, fast,
and dynamic sensations.
The primary sensation in ETS is achieved proportional
to Current Density. Therefore, an array can be controlled such that
only one, two or multiple tactors are felt at a time. JKI's ETS programmed
routines in the Driver enclosure, or those creased by external control,
provides an unlimited number of combinations and effects across waveforms,
pulse trains, spatial effects, amplitude, and intensity.
Years of in-house research at JKI in electrostimulation
has provided the ability of shaping the current path within a tactor array
with the use of Tri-Polar Electrodes. Our Tri-Polar Driving technology
allows the ultimate in real-time flexibility in response and sensation.
JKI's use of embedded control stages within the Driver enclosure provides
coordinated control of small and large numbers of independent tactor outputs.
ETS Pro's and Con's
1) ETS outputs span the range from imperceptible
to noticeable to pleasant to attention getting to painful. Even at
highest outputs, there is no damage to the body, only the sensation of
pain. Most useful amplitudes are in the pleasant to attention getting
2) The primary output is an electronic
pulse train, which is easy to sculpt to achieve the correct perception,
comfort (discomfort), and .
3) Tactors are individually addressable
through the Driver's output controller and have instantaneous response
time. Very dramatic perception effects can be created.
4) Electrostimulation effects both fast
and slow nerve fibers, therefore it is easy to create both static and dynamic
sensations, illusions of motion, and other tactile perceptions.
5) JKI's anti-accomodation stimulation
techniques provide longer lasting stimulation without the need to creep
higher in amplitude, common in most electrostimulation applications.
6) ETS units draw relatively far less current
for the same ability to produce stimulation than vibration based or heat
based tactile techniques.
7) ETS outputs maintain their sensation
levels even in high stress, vibration, cold, hot, high 'G', weightless,
1) Users must wear tactor arrays on their
bare skin. Although surface contact does not have to be prepared
will typical electrodes, good to fair contact is recommended.
2) Users may have to get used to the sensation
and the perception of being hurt by the electrostimulation stage.
Having a Kill-Switch in hand is a comforting placebo.
ETS Tactor Arrays
JKI builds several standard and custom ElectroTactile
Arrays to suit mapping and applications. Arrays are designed to maximize
wearibility, comfort, and provide a straightforward translation from the
external input on condition to the user. Critical to their construction
is the ability to be used and worn in the user's intended environment.
Several layouts have been created for high resolution
outputs and natural mapping. Some radial and circular arrays use
8 or 12 tactors to match to cardinal headings of a compass or the hands
of a clock, hence increasing the ability of the user to understand the
mapping application. Arrays are scalable such that a belt or vest
may have several radial levels to provide orientation and another variable
such as height, type of input (weapon status, communication, navigation)
all synthesized into one application.
JKI builds Tactor Arrays using either conductive
rubber or stamped tin. Surface area is maintained per type.
Several types and sizes are available. Common arrays are thorax belts,
torso dials, wrist cuffs, back-of-the-hand dials, arm/leg strips, and arm/leg
grids. Arrays have also been built for the soles of the feet, the
neck, and other non-typical applications.
VTS Theory of Operation
VibroTactile Stimulation (VTS) uses vibration
or mechanical impact to affect a tactile sensation.
A common method has been the application of off-center
motors ( pager vibrators). Motor based vibration elements have only
one level of variations, speed-amplitude. The faster they rotate,
the higher the frequency of vibration. Their frequency response is
poor, sometimes taking 300-500 msec to run down.
JKI has developed its own line of VibroTactor
and RamTactor elements based on reciprocating inductive driving of magnets.
These coil based elements are driven electronically and react quickly to
changes in waveform, amplitude, frequency. This method of driving
the tactors decreases transient response, making their sensation sharper,
quicker and more dynamic. Adjustments in waveform, pulse train, frequency,
duty cycle and amplitude each contribute to creating a versatile sensation
A secondary benefit of VibroTactile stimulation
is low frequency audio. In some cases when primary VTS functions
are not in use, JKI's VTS elements may act like a replacement sub-woofer
with the proper input, filtering, and amplification measured installed.
VTS Pros and Cons
1) VibroTactor Elements are faster and
have more dynamic response than motor based vibrators.
2) Elements do not require skin contact
such as in ETS and can be mounted over some clothing.
3) Faster response allows more dynamic
routines and levels of perception to be created.
4) Fast transient response allows crisp,
fast, and complex patterns to be generated.
5) The amplitude is scalable to generate
warm fuzzys to hard thumps across frequencies, well defined pulse trains,
6) Elements can be mounted in supports
or seats that press against the body, no need for wearable garmenting in
1) All vibration elements are susceptible
to not working or being not perceived in high 'G' or vibration environments.
2) VibroTactors consume a bit more power
than similar ElectroTactor systems for the same level of perception.
3) Magnetic fields put off by vibration
elements can cause errors in nearby magnetic sensitive instruments like
motion capture or compass navigation devices.
4) Extended heavy excitation may lead to
5) Wearing larger arrays may become heavy.
JKI custom builds wearable VTS Arrays for use
under or over clothing, in most configurations and arrangements.
One of three standard VibroTactor Elements are typically used, but custom
VibroTactor Elements are often created for unique applications.
Requirements are usually intended body location, peak amplitude, and peak
operation excitation. Such variables are part of the application
Especially critical to large arrays is the ability
of each tactor to be placed correctly and have good contact with the body:
no contact - no sensation. Garmenting with support strapping is typically
created with the user in their intended environment in mind. JKI's
garment expert has been building instrumented garments since 1990.
All instrumented garments has a good range of sizes.
JKI's VTS Driver outputs may be compatible with
existing motor or coil-based ElectroTactile elements.
Arrays created with JKI's VibroTactor and RamTactor
elements can be placed in fixed mountings like chairs, seats, or other
body contacting supports. RamTactors typically require deeper mounting
clearances and cushion frames are preferred. Fixed Mountings typically
decreases the wear on cables, and provides for heat dissipation measures
allowing elements to be driven harder and longer and eliminates donning
bulky equipment. A more secure (i.e. heavier) base increases tactile
Mapping is the process of symbolically transferring
inputs or status conditions to a touch sensible variable. Elements
of information are presented to a user tactilely. This requires three
1) Tactor Arrays capable to presenting the information
with a number, orientation, and layout to be significant to the user.
2) Conversion Algorithms capable to map single
or complex data points to tactile outputs that are clear and perceivable
by the user.
3) Familiarity / Experience of the user
to recognize the input and its significance.
Discrete Mapping Approach
Discrete Mapping is an example of a fixed or
only (closed-loop) application. Such mapping schemes can easily be
reduced to a 'black box' device for wearable applications or installation
in equipment. Three Discrete Mapping examples are described below:
1) Fighter Pilot Incoming Missile Detection,
based on a 3 x 12 Ch. radial Tactor Belt:
|Direction of Ground
Orientation of Missile
|First Stimulation on Array
Main Stimulation channel on Array (3 hits)
Frequency of Pulse Train
Amplitude of Pulses
Change to High-Output Spiral Pattern
2) Magnetic Orientation, based on a 12 Ch. circular
|Direction of North
Deviation from Setting to Coarse
Threshold Alarm ( from some quantity, proximity,
|First Stimulation on Array
(1 hit, pause)
Main Stimulation on Array (3/5 hits)
Intensity of Pulse Train
Occasional Spiral Pattern
3) Communication when voice/visually restricted,
based on 6 Ch. Wrist Band Array
|Look at Controller/Co-Workers
Get on radio
|Each tactor mapped to
Patterns mapped to job functions
Various sequences / intensitys or patterns for
each type of alarm
Simplified codes could be used (similar to Morse
Code) to relay information (phone call, come in, or other alpha-numeric
In this last case, a touch based input device
would allow the user to similarly 'ping' a co-workers or the controller
for attention. More advanced use of a touch input would allow a tactile
form of 'text messaging'
General Mapping Approach
General Mapping is an example of undefined control
where several settings, patterns, and scenarios are capable to be generated,
typically in a test and development environment. In test and development
phase, one may desire to experiment with several tactile mapping symbologies
to create an optimal scenario. The General Mapping Approach may still
involve fixed inputs and closed-loop aspects but is universally expandable.
As discrete applications consist of a driver with
built in input mapping, the General Mapping Approach requires drivers to
be externally controlled through JKI's TSComm protocol. TSComm can
be generated through Manual Control Consoles, Software based Computer Programs.
Manual Control Console (MCC)
A MCC allows all functions to be manually adjusted,
has LED/LCD displays of critical settings, incorporates safetys, alarms,
timing, and high impedance communication with drivers. Inputs
from a secondary source can also be interpreted and mapped with specific
modules in the MCC. Tactile effects and patterns can be developed
and tested. Both large scale and reduced function MCCs are
Computer Based Controller
A computer may be used to provide the control
and communications to the ETS/VTS Drivers. A LabView program
has been used to mimic the functions of a MCC. The benefit of a computer
based controller is the flexibility of designing new routines, applications,
and reading any instrumentation outputs from the drivers.
JKI's TSComm protocol developed for communicating
with ETS, VTS, and Large Scale Array (LSA) systems is included with any
driver product. All MCCs and computer based systems use TSComm.
TSComm is a bi-directional timed control protocol designed with flexibility
and safety in mind. TSComm can be generated via RS/RF232 based or
your custom embedded controller. TSComm consists of syntax specific
packetized control codes and value codes which may be implemented through
direct wire, high impedance, optical or RF interfaces.