SSVEP-based Experimental Procedure for Brain-Robot Interaction with Humanoid Robots
Summary
The overall goal of this method is to establish an SSVEP-based experimental procedure by integrating multiple software programs to enable the study of brain-robot interaction with humanoid robots, which is prospective in assisting the sick and elderly as well as performing unsanitary or dangerous jobs.
Abstract
Brain-Robot Interaction (BRI), which provides an innovative communication pathway between human and a robotic device via brain signals, is prospective in helping the disabled in their daily lives. The overall goal of our method is to establish an SSVEP-based experimental procedure by integrating multiple software programs, such as OpenViBE, Choregraph, and Central software as well as user developed programs written in C++ and MATLAB, to enable the study of brain-robot interaction with humanoid robots.
This is achieved by first placing EEG electrodes on a human subject to measure the brain responses through an EEG data acquisition system. A user interface is used to elicit SSVEP responses and to display video feedback in the closed-loop control experiments. The second step is to record the EEG signals of first-time subjects, to analyze their SSVEP features offline, and to train the classifier for each subject. Next, the Online Signal Processor and the Robot Controller are configured for the online control of a humanoid robot. As the final step, the subject completes three specific closed-loop control experiments within different environments to evaluate the brain-robot interaction performance.
The advantage of this approach is its reliability and flexibility because it is developed by integrating multiple software programs. The results show that using this approach, the subject is capable of interacting with the humanoid robot via brain signals. This allows the mind-controlled humanoid robot to perform typical tasks that are popular in robotic research and are helpful in assisting the disabled.
Introduction
Brain-Robot Interaction (BRI), which provides an innovative communication pathway between human and a robotic device via brain signals, is prospective in helping the disabled in their daily lives 1,2. A variety of methods are able to acquire brain signals either invasively or non-invasively, such as electrocorticography (ECoG), electroencephalograph (EEG), functional magnetic resonance imaging (fMRI), etc. The most commonly used non-invasive method for building the BRI system is to acquire EEG signals from electrodes placed on the scalp. This method is inexpensive, easy to use, and provides an acceptable temporal resolution 3. Among a variety of robotic devices, humanoid robots are advanced as they are created to imitate some of the same physical and mental tasks that humans undergo daily. BRI with a humanoid robot will play an important role in assisting the sick and elderly, as well as performing unsanitary or dangerous jobs. But control of a humanoid robot through BRI system is highly challenging, as the humanoid robot with full body movement is developed to perform complex tasks such as personal assistance 4, 5.
Steady-State Visual Evoked Potential (SSVEP) is a type of brain signal evoked by the modulation of visual stimulus at a given frequency 6. It contains sinusoids at the fundamental and harmonic frequencies of the flickering stimulus, and prominently appears throughout the visual cortex in the occipital region of the scalp 7. The reason for choosing the SSVEP signals is that the SSVEP-based BRI system yields relatively high information transfer rate and requires less training 8. Other types of brainwaves, such as event-related potentials (ERPs) 9 or motor-imagery (MI) potentials 10, can also be embedded into this experimental procedure.
Our procedure for brain-robot interaction with humanoid robots is based on Cerebot – a mind-controlled humanoid robot platform – consisting of an EEG data acquisition system and a humanoid robot 11. The EEG system is able to record, pre-process and display bio-potential signals acquired by various types of electrodes. It provides multiple analog I/Os and digital I/Os and is capable of recording up to 128 signal channels simultaneously at a sampling rate of 30 kHz with 16-bits resolution. Its software development kits in C++ and MATLAB are easy for users to design the experimental procedures. The humanoid robot has 25 degrees of freedom and is equipped with multiple sensors, including 2 cameras, 4 microphones, 2 sonar rangefinders, 2 IR emitters and receivers, 1 inertial board, 9 tactile sensors, and 8 pressure sensors. It provides Choregraphe and C++ SDK for creating and editing movements and interactive robot behaviors.
The overall goal of this method is to establish an SSVEP-based experimental procedure by integrating multiple software programs, such as OpenViBE, Choregraph, Central software as well as user developed programs written in C++ and MATLAB, to enable the study of brain-robot interaction with humanoid robots 11. Figure 1 shows the system structure. The dedicated stimulus presentation computer (SPC) displays the User Interface to provide the subject with visual stimuli, instructions and environmental feedbacks. The dedicated data processing computer (DPC) runs the Data Recorder and the Offline Data Analyzer in the offline training process, and runs the Online Signal Processor and the Robot Controller for the online control of the humanoid robot. Compared with other SSVEP-based control systems, our system is more reliable, more flexible, and especially more convenient to be reused and upgraded as it is developed by integrating a number of standardized software packages, such as OpenViBE, Choregraph, Central software, and modules written in C++ and MATLAB.
The following procedure was reviewed and approved by Tianjin medical university general hospital ethics committee, and all subjects gave written consent.
Protocol
Representative Results
Discussion
This paper presents an SSVEP-based experimental procedure to establish the brain-robot interaction system with humanoid robots by integrating multiple software programs. Because human intent is perceived by interpreting real-time EEG signals, it is critical to verify the electrode connections and EEG signal qualities before conducting the experiment. If signals acquired from all the electrodes are of poor qualities, it is necessary to check the connection of the ground and reference electrodes first. If there are problem…
Divulgations
The authors have nothing to disclose.
Acknowledgements
The authors would like to express their gratitude to Mr. Hong Hu for his assistance in performing the experiments reported in this paper. This work was supported in part by the National Natural Science Foundation of China (No. 61473207).
Materials
| Cerebus EEG Data Acquisition System | Blackrock Microsystems | 4176-9967 | |
| NAO humanoid robot | Aldebaran Robotics | H25 | |
| EEG cap | Neuroscan | 8732 | |
| Ten20 Conductive gel | Weaver and company | 10-20-8 |
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