Optimization Of Stimulation-paradigm For P300 Input System

Brain-Computer Interface,also called the BCI,shows that we can make direct control and communication between human brain and computer or other external devices.In the field of BCI,many scholars have paid much attention on P300 signal for its low requirement of training,so that it is very convenient to realize artificial intelligence system.However,there are still many deficiencies in the spelling/input system based on P300,which require much progress,such as spelling rate,congestion effect,user acceptance and so on.In order to better reflect the performance of P300 spelling system,this article has done much effort on the following respects:1.The research of this paper is based on the BCI P300 character input system,mainly from respect of the stimulation paradigm and the speller interface.Based on the study of some existing paradigms,we proposed a new paradigm which tests P300 signal and controls the flashing at the same time,then we discussed on the speller interface in two fields(various types of hybrid,matrix size),and finally the P300 character input system was implemented on the BCI2000 platform.2.Comparing with the traditional Row-Column input system,this system has the following characteristics: after only a short time boring training,the user then enter a dynamic controlling mode to spell what he/she wants to show in the screen,which improves the user experience;and as the characters flashing in the screen,we try to narrow the range of the target stimuli,as well as the number of characters flashing,which will increase the accuracy of spelling.3.Designing of the stimulus paradigm: after the system get the user's training data,we can get the user's P300 signal mode by analysing and classifying his/her EEG signal,the signal mode is then used in the new paradigm;by calculating the response value of each character in the spelling interface,we can determine the target stimuli by dynamic method,which greatly improved the recognition speed of the speller.It can be seen from the experimental data that the improved P300 character input system not only improves the spelling rate of the system,but also improves the accuracy of spelling.