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.
 

ElectroTactile

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

Advantages.
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 levels.
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, and  environments.

Drawbacks.
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.

VibroTactile Stimulation

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 generator.

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

Advantages.
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, and amplitudes.
6)  Elements can be mounted in supports or seats that press against the body, no need for wearable garmenting in some applications. 

Drawbacks.
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 heat accumulation.
5)  Wearing larger arrays may become heavy.

VTS Arrays

Wearable Mountings.
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 specifications. 

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.

Fixed Mountings.
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 response. 

Mapping

Symbology
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 components:
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:

2) Magnetic Orientation, based on a 12 Ch. circular Tactor Patch

3)  Communication when voice/visually restricted, based on 6 Ch. Wrist Band Array

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. 

Control Methods

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 available.

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. 

TSComm Protocol
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.