The Research Of Tactile Vision Substitution System Based On The Finger-Scanned Electrotactile Display

The tactile vision substitution technology is that translating the visional informationinto tactile sensation, by some methods of physical stimulation, then sending to the brainarea related in which those tactile messages are recombined and reproduced into visionalinformation. Braille is the most classic example of tactile substitution. Besides aiding forthe visually impaired, there still are many other valuable applications in the medical,military and entertainment fields and so on. For example, the remote tactile presentationtechniques make the remote manipulator be available for the remote information,especially in the occasions of underwater exploration and remote surgery. In the intensecombat flight, tactile display shows great potential in informing the flight with controlinformation. Adding tactile path can create a more realistic in-game atmosphere.The paper have designed and implemented a tactile vision substitution system basedon the fingertips. The system consistes of image acquisition, image processing, controlunit, drive of electrode and electrode array. The8x8electrode matrix, in the form ofprinted circuit board, adoptes multi-channel time-sharing control mode. The isolationvoltage module supplies power for the control unit and the stimulation voltage module,which not only implementes the function of isolating strong stimulation signal from weakcontrol signal, but also greatly simplifies the system design and reduced the volume.The main research work in the paper has listed as followed:1) The paper carried on a series of specific research on the impact of stimulationwaveform parameters on the electrotactile, and came up with modified skin-electrodeinterface models in different condition of electrical stimulation based on the classicmodel.2) And then the paper discussed the influence of the stimulation frequency, pulsewidth and current on the electrotactile, respectively by combining the theoretical modelswith the experimental results, which proved that the experimental results conformed tothe theoretical models very well. This provided theory basis for the electro-adaptive adjustment and electrical stimulation fatigue relief, and broke an approach to realizeautomatic feedback control of the electrotactile at the same time.3) In the case of appropriate electrical stimulation waveform, the stimulationthreshold experiments were carried out on each fingertip to figure out the suitablestimulation spot.4) Finally, according to the above experiments, direction and simple patternrecognition were carried out on the TVSS. And the results indicated that the electriccurrent played a leading role in the perceived intensity, while the frequency and pulsewidth impacted on the perceived quality. The stimulation waveform with frequencyranging from10to100Hz, pulse with from0.25to2ms, worked out comfortableelectrotactile, and frequency from10to70led to better recognition rate. There weredifferences among different fingertips. At last it proved that the TVSS could get goodrecognition rate to simple patterns.