A study on a robot arm driven by three-dimensional trajectories predicted from non-invasive neural signals.
BACKGROUND
A brain-machine interface (BMI) should be able to help people with disabilities by replacing their lost motor functions. To replace lost functions, robot arms have been developed that are controlled by invasive neural signals. Although invasive neural signals have a high spatial resolution, non-invasive neural signals are valuable because they provide an interface without surgery. Thus, various researchers have developed robot arms driven by non-invasive neural signals. However, robot arm control based on the imagined trajectory of a human hand can be more intuitive for patients. In this study, therefore, an integrated robot arm-gripper system (IRAGS) that is driven by three-dimensional (3D) hand trajectories predicted from non-invasive neural signals was developed and verified.


METHODS
The IRAGS was developed by integrating a six-degree of freedom robot arm and adaptive robot gripper. The system was used to perform reaching and grasping motions for verification. The non-invasive neural signals, magnetoencephalography (MEG) and electroencephalography (EEG), were obtained to control the system. The 3D trajectories were predicted by multiple linear regressions. A target sphere was placed at the terminal point of the real trajectories, and the system was commanded to grasp the target at the terminal point of the predicted trajectories.


RESULTS
The average correlation coefficient between the predicted and real trajectories in the MEG case was [Formula: see text] ([Formula: see text]). In the EEG case, it was [Formula: see text] ([Formula: see text]). The success rates in grasping the target plastic sphere were 18.75 and 7.50 % with MEG and EEG, respectively. The success rates of touching the target were 52.50 and 58.75 % respectively.


CONCLUSIONS
A robot arm driven by 3D trajectories predicted from non-invasive neural signals was implemented, and reaching and grasping motions were performed. In most cases, the robot closely approached the target, but the success rate was not very high because the non-invasive neural signal is less accurate. However the success rate could be sufficiently improved for practical applications by using additional sensors. Robot arm control based on hand trajectories predicted from EEG would allow for portability, and the performance with EEG was comparable to that with MEG.
Interdisciplinary Program for Bioengineering, Graduate School, Seoul National University, Seoul, 110-744, Korea. kyj182731@naver.com.
Yoon Jae
YJ
Kim
Interdisciplinary Program for Bioengineering, Graduate School, Seoul National University, Seoul, 110-744, Korea. pswyrn@gmail.com.
Sung Woo
SW
Park
Interdisciplinary Program in Neuroscience, Graduate School, Seoul National University, Seoul, 151-742, Korea. honggi@meg.re.kr.
Hong Gi
HG
Yeom
Department of Rehabilitation Medicine, Seoul National University Hospital, Seoul, 110-744, Korea. msbang@snu.ac.kr.
Moon Suk
MS
Bang
Sensory Organ Research Institute, Seoul National University, Seoul, 151-742, Korea. jskim@meg.re.kr.
June Sic
JS
Kim
Interdisciplinary Program in Neuroscience, Graduate School, Seoul National University, Seoul, 151-742, Korea. chungc@snu.ac.kr.|Department of Neurosurgery, Seoul National University Hospital, Seoul, 110-744, Korea. chungc@snu.ac.kr.|Department of Brain and Cognitive Sciences, Seoul National University College of Natural Sciences, Seoul, 151-742, Korea. chungc@snu.ac.kr.
Chun Kee
CK
Chung
Department of Biomedical Engineering, Seoul National University College of Medicine, Seoul, 110-799, Korea. sungwan@snu.ac.kr.|Institute of Medical and Biological Engineering, Seoul National University, Seoul, 151-742, Korea. sungwan@snu.ac.kr.
Sungwan
S
Kim
D000328:Adult; D001132:Arm; D001921:Brain; D062207:Brain-Computer Interfaces; D004569:Electroencephalography; D005260:Female; D006225:Hand; D018737:Hand Strength / Q000502:physiology; D006801:Humans; D015225:Magnetoencephalography; D008297:Male; D012371:Robotics; D012815:Signal Processing, Computer-Assisted; D055815:Young Adult