A Wearable Braille Sensor System With a Post Processing

This paper is a study on the development of a wearable sensor system for reading Braille. The study is intended to develop a compact tactile sensor system, which uses a polyvinylidene fluoride (PVDF) film for the sensory receptor. The sensor is mounted onto a fingertip and moved over Braille manually to obtain the output. Since the unsteady movements yield variations in the waveforms, a robust recognition system has been developed. In this study, the post processing is introduced into the recognition system for the improvement of the performance. Two different methods of post processing are developed and examined. In the first method, an appropriate letter string is generated by evaluating the connectivity of letters with information on signals. In the second method, the dictionary in which letter strings are recorded is incorporated as the prior knowledge. Finally, both the methods of post processing are combined to enhance the performance. The combined post processing is incorporated to the wearable sensor system, and the performance of the sensor system is evaluated experimentally. The results show that the sensor system is effective to recognize Braille.