An online multi-channel SSVEP-based brain–computer interface using a canonical correlation analysis method

TLDR

Steady‑state visual evoked potentials (SSVEP) are increasingly used in brain‑computer interfaces, but current systems suffer from limited speed, user variability, and usability issues. This study introduces an online multi‑channel SSVEP‑based BCI that employs canonical correlation analysis to extract frequency information, aiming to address these shortcomings. The system uses nine occipital‑parietal channels, a 2‑second window, and the first harmonic, with parameters optimized offline and applied to online testing on 12 subjects. The optimized BCI achieved 95.3 % accuracy and 58 ± 9.6 bits min⁻¹, demonstrating high performance, low user variation, and ease of setup without requiring channel selection or parameter tuning.

Abstract

In recent years, there has been increasing interest in using steady-state visual evoked potential (SSVEP) in brain–computer interface (BCI) systems. However, several aspects of current SSVEP-based BCI systems need improvement, specifically in relation to speed, user variation and ease of use. With these improvements in mind, this paper presents an online multi-channel SSVEP-based BCI system using a canonical correlation analysis (CCA) method for extraction of frequency information associated with the SSVEP. The key parameters, channel location, window length and the number of harmonics, are investigated using offline data, and the result used to guide the design of the online system. An SSVEP-based BCI system with six targets, which use nine channel locations in the occipital and parietal lobes, a window length of 2 s and the first harmonic, is used for online testing on 12 subjects. The results show that the proposed BCI system has a high performance, achieving an average accuracy of 95.3% and an information transfer rate of 58 ± 9.6 bit min−1. The positive characteristics of the proposed system are that channel selection and parameter optimization are not required, the possible use of harmonic frequencies, low user variation and easy setup.