Kuo-Kai Shyu,Member,IEEE, Yun-Jen Chiu, Po-Lei Lee, Jia-Ming Liang,and Shao-Hwo Peng Presenter ： Zi-Wei Wang Adviser ： Dr. Yeou-Jiunn Chen Date:2016/1/5 1

1. Introduction 2. Materials and Methods 3. Experimental Results 4. Discussion 5. Conclusion 2

 Brain–Computer Interface  It can help severe motor disabilities people problem.  The brain’s commands are identified by extracting Electroencephalograms(EEG).  SSVEP-Based BCI System  Simple system configuration  Short training time  High-Information Transfer Rate 3

 SSVEP-Based BCI system  It is improper to design fixed frequency flickering stimuli for all users.  Users feel uncomfortable and easily tired. 4 Data:Brain -computer interface restores walking after paraplegia

 Amplitude Response  Low-frequency region  Medium-frequency region  High-frequency region  Frequency  Frequency band of 5–9.9 Hz  Duty-Cycle is 0.4 at frequency of 10Hz  One command/One frequency to multi command/one frequency 5

6 Fig. 1. Average FFT amplitude spectrum of 12 projects.

7 Fig. 2. SSVEP response of four subjects in different frequencies (21–36 Hz) and duty-cycles (10%–90%).

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Fig.4. Flashing command sequence of the flicker frequency/duty-cycle selection mode. 9

Fig. 5. Block diagram of SSVEP signal processing. 10

Fig. 6. Flow process of SLIC method. 11

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13 Fig. 8. Flashing command sequence is used to validate duty-cycles influence on SSVEP response.

14 Fig.9. SSVEP response of subjects using 21 Hz frequency with different duty cycle stimuli in four flickering series.

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 Uses higher frequencies stimuli without sacrificing accuracy or degrading the system.  It also finds the optimal flicker duty-cycle to SSVEP is user-related but not time-related.  The phase technique is used to extend the number of command flickers based on the obtained optimal stimuli frequency.  The low-cost system can be afforded by more families to use at home not only in hospital. 18

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