A review of hybrid brain-computer interface systems <s> P300-Motor Imagery Hybrid BCI. <s> This paper describes a control strategy to drive a wheelchair in a building environment by thought. The user selects the destination in a list of predefined locations of interest using a slow but safe P300 EEG interface. The robotic wheelchair navigates autonomously toward destination following virtual guiding paths. Along the way the user has the possibility to stop the movement using a fast μβ-rhythm BCI. Experiments demonstrate how healthy subjects can navigate safely in an home-like environment using this novel hybrid BCI. <s> BIB001 </s> A review of hybrid brain-computer interface systems <s> P300-Motor Imagery Hybrid BCI. <s> This paper presents a hybrid brain-computer interface (BCI) control strategy, the goal of which is to expand control functions of a conventional motor imagery or a P300 potential based BCI in a virtual environment. The hybrid control strategy utilizes P300 potential to control virtual devices and motor imagery related sensorimotor rhythms to navigate in the virtual world. The two electroencephalography (EEG) patterns serve as source signals for different control functions in their corresponding system states, and state switch is achieved in a sequential manner. In the current system, imagination of left/right hand movement was translated into turning left/right in the virtual apartment continuously, while P300 potentials were mapped to discrete virtual device control commands using a five-oddball paradigm. The combination of motor imagery and P300 patterns in one BCI system for virtual environment control was tested and the results were compared with those of a single motor imagery or P300-based BCI. Subjects obtained similar performances in the hybrid and single control tasks, which indicates the hybrid control strategy works well in the virtual environment. <s> BIB002 </s> A review of hybrid brain-computer interface systems <s> P300-Motor Imagery Hybrid BCI. <s> We propose an on-line hybrid BCI system that combines P300 and ERD. By employing both brain activity patterns (BAPs) in parallel and asynchronously, the system can issue different types of commands, for example, in robotic control scenarios. We present a method for reliably distinguishing between the two BAPs. We examined the level of false positives in P300 classification while a subject tries to evoke an ERD. We found this level to be as low as for regular P300 trials. Our system thus assumes the presence of ERD whenever classification of all P300 symbols is negative. Empirical results indicate that subjects can achieve good control over the hybrid BCI. In particular, subjects can switch spontaneously and reliably between the two BAPs. <s> BIB003
Another possible combination for a hybrid BCI is P300 and motor imagery (MI)-based BCI BIB001 BIB002 BIB003 . The basic concept in this type of hybrid is based on the features of P300 and ERD/ERS in control applications. P300 is a reliable BCI type for selecting one item out of several items and can be used for discrete control commands. On the other hand, due to the low degree of freedom presented by MI-based BCI, this type of BCI is more efficient for continuous control commands. These two types of BCIs can be joined to present more complicated control commands in one task. In BIB001 , for controlling a wheelchair in a home environment, several approaches using different BCI techniques were introduced. The wheelchair control commands were divided into three steps. Step 1 (Destination Selection). In this task, the user should select the destination of the wheelchair motion by selecting one of the items among a list of destinations. To implement this control command, an accurate and reliable interface is needed and false acceptance rates should be as low as possible. For this task, a P300 BCI presented at a screen was utilized. The experiments on healthy subjects showed a response time of about 20 seconds, the false acceptance rate 2.5% and the error less than 3%. The results showed that P300 was an appropriate option for the interface. But there are a couple of points to be considered: First, all subjects were healthy. For users with severe disability, the accuracy of the results may differ. Second, there is concern about the applicability of the interface, if it is proper for daily use. A more applicable situation should be considered for evaluating this approach.