BCI Technology And Meridian Magnetic Stimulation System Based On Brain Control

BCI system is a communication system for controlling a device, e.g. computer, or wheelchair, by human intensions, which does not depend on the brain’s normal output pathways of peripheral nerves and muscles but relies on the detectable signals representing responsive or intentional brain activities. BCI system use computer and other equipment to gather and analyze EEG data under specific environment and tasks, then the brain information is translated into control commands to achieve the purpose of controlling external devices. BCI provides a new communication mode that it can help people with physical disabilities to restore the ability of communicating with the outside world. And it also can help them to achieve control of external devices, such as the rehabilitation wheelchair, household appliances and computer games and so on. Motor imagery BCI system is the currently more study of BCI systems. It can control external devices according to imagine actions. Currently, the asynchronous motor imagery BCI system, because of its flexibility and practicality, has a wide application in BCI technology.This article conduct a deeply study of the EEG acquisition, signal analysis and external control module based on the motor imagery BCI systems. Based on the laboratory existing meridian magnetic stimulation system, this article designed a method of brain control to adjust the stimulation parameter. The specific works are as follows.(1) Extracting EEG feature evoked by motor imaginary based on wavelet statistical method. This article proposed a method of wavelet analysis to extract the feature of EEG evoked by motor imagery. And then recognize the feature by support vector machine. The accuracy of the recognition can reach 90.7% within 3.5 seconds. And the result can well meet the requirements of the online BCI systems.(2) Feature recognition of EEG evoked by motor imagery in asynchronous BCI systems. This article design a twice-classifier combined threshold determination with SVM classifier to recognize the EEG feature of asynchronous BCI. The method not only reduces the cost of the system time, but also improves the recognition accuracy. An online asynchronous motor imagery BCI system is also designed based on this method. The system can achieve the real-time feature recognition, which provides an effective pathway for the practical application of BCI.(3) Magnetic stimulation coil optimization and research of meridian magnetic stimulation of brain control. This part design a kind of trumpet-shaped magnetic stimulation coil based on the laboratory existing meridian magnetic stimulation system. The coil in terms of the focus and stimulate depth have reached the requirment of meridian magnetic stimulation. This article also design the method of meridian magnetic stimulation system adjustment based on the a-wave energy, the dynamic EEG topographic maps and asynchronous motor imagery BCI. This method get the best magnetic stimulation parameters and also improve the effectiveness of rehabilitation therapy and enhance the patients’initiative to participate in the treatment.The method of EEG feature extraction and asynchronous BCI systems feature recognition as well as the meridian magnetic stimulation parameter adjustment method proposed by this article laies a solid foundation for the development of BCI systems.