Abstract The steady-state visual-evoked potential-based brain-computer interface (SSVEP-BCI) is a typically recognized visual stimulus frequency from brain responses. Each frequency represents one command to control a machine. For example, multiple target stimuli with different frequencies can be used to control the moving speeds of a robot. Each target stimulus frequency corresponds to a speed level. Such a conventional SSVEP-BCI is choice selection paradigm with discrete information, allowing users to discretely control the speed of a movable object. This can result in non-smooth object movement. To overcome the problem, in this study, a conceptual design of a SSVEP-BCI with continuous information for continuous control is proposed to allow users to control the moving speed of an object smoothly. A predictive model for SSVEP magnitude variation plays an important role in the proposed design. Thus, this study mainly focuses on a feasibility study concerning the use of SSVEP magnitude prediction for BCI. A basic experiment is therefore conducted to gather SSVEP responses from varying stimulus intensity using times with a fixed frequency. Random Forest Regression (RF) is outperformed by simple regression and neural networks in these predictive tasks. Finally, the advantages of the proposed SSVEP-BCI is demonstrated by streaming real SSVEP responses from ten healthy subjects into a brain-controlled robotic simulator. The results from this study show that the proposed SSVEP-BCI containing both frequency recognition and magnitude prediction is a promising approach for future continuous control applications.
