Hao-Teng Hsu, Kuo-Kai Shyu, Chuan-Chih Hsu, Lung-Hao Lee, and Po-Lei Lee*.
IEEE Transactions on Neural Systems and Rehabilitation Engineering (IEEE TNSRE), 29, pages 2754-2764.
Abstract
Steady-state visual evoked potential (SSVEP) has been used to implement brain-computer interface (BCI) due to its advantages of high information transfer rate (ITR) and high accuracy. In recent years, owing to the develop- ments of head-mounted device (HMD), the HMD has become a popular device to implement SSVEP–based BCI. However, an HMD with fixed frame rate only can flash at its sub- harmonic frequencies which limits the available number of stimulation frequencies for SSVEP-based BCI. In order to increase the number of available commands for SSVEP- based BCI, we proposed a phase-approaching (PA) method to generate visual stimulation sequences at user-specified frequency on an HMD. The flickering sequence generated by our PA method (PAS sequence) tries to approximate user- specified stimulation frequency by means of minimizing the difference of accumulated phases between our PAS sequence and the ideal wave of user-specified frequency. The generated sequence of PA method determines the brightness state for each frame to approach the accumu- lated phase of the ideal wave. The SSVEPs evoked from stimulators, driven by PAS sequences, were analyzed using canonical correlation analysis (CCA) to identify user’s gazed target. In this study, a six-command SSVEP-based BCI was designed to operate a flying drone. The ITR and detection accuracy are 36.84 bits/min and 93.30%, respectively.
