Unimanual versus bimanual motor imagery classifiers for assistive and rehabilitative brain computer interfaces

Bimanual movements are an integral part of everyday activities and are often included in rehabilitation therapies. Yet electroencephalography (EEG) based assistive and rehabilitative brain computer interface (BCI) systems typically rely on motor imagination (MI) of one limb at the time. In this study we present a classifier which discriminates between uni-and bimanual MI. Ten able bodied participants took part in cue based motor execution (ME) and MI tasks of the left (L), right (R) and both (B) hands. A 32 channel EEG was recorded. Three linear discriminant analysis classifiers, based on MI of L-B, B-R and B--L hands were created, with features based on wide band Common Spatial Patterns (CSP) 8-30 Hz, and band specifics Common Spatial Patterns (CSPb). Event related desynchronization (ERD) was significantly stronger during bimanual compared to unimanual ME on both hemispheres. Bimanual MI resulted in bilateral parietally shifted ERD of similar intensity to unimanual MI. The average classification accuracy for CSP and CSPb was comparable for L-R task (73±9% and 75±10% respectively) and for L-B task (73±11% and 70±9% respectively). However, for R-B task (67±3% and 72±6% respectively) it was significantly higher for CSPb (p=0.0351). Six participants whose L-R classification accuracy exceeded 70% were included in an on-line task a week later, using the unmodified offline CSPb classifier, achieving 69±3% and 66±3% accuracy for the L-R and R-B tasks respectively. Combined uni and bimanual BCI could be used for restoration of motor function of highly disabled patents and for motor rehabilitation of patients with motor deficits

A review and consideration on the kinematics of reach-to-grasp movements in macaque monkeys

The bases for understanding the neuronal mechanisms that underlie the control of reach-to-grasp movements among nonhuman primates, particularly macaques, has been widely studied. However, only a few kinematic descriptions of their prehensile actions are available. A thorough understanding of macaques' prehensile movements is manifestly critical, in light of their role in biomedical research as valuable models for studying neuromotor disorders and brain mechanisms, as well as for developing brain-machine interfaces to facilitate arm control. This article aims to review the current state of knowledge on the kinematics of grasping movements that macaques perform in naturalistic, semi-naturalistic, and laboratory settings, to answer the following questions: Are kinematic signatures affected by the context within which the movement is performed? In what ways is kinematics of humans' and macaques' prehensile actions similar/dissimilar? Our analysis reflects the challenges involved in making comparisons across settings and species due to the heterogeneous picture in terms of the number of subjects, stimuli, conditions, and hands used. The kinematics of free-ranging macaques are characterized by distinctive features that are exhibited neither by macaques in laboratory setting nor human subjects. The temporal incidence of key kinematic landmarks diverges significantly between species, indicating disparities in the overall organization of movement. Given such complexities, we attempt a synthesis of extant body of evidence, intending to generate some significant implications for directions that future research might take, to recognize the remaining gaps and pursue the insights and resolutions to generate an interpretation of movement kinematics that accounts for all settings and subjects

Waypoint-Based Imitation Learning for Robotic Manipulation

While imitation learning methods have seen a resurgent interest for robotic manipulation, the well-known problem of compounding errors continues to afflict behavioral cloning (BC). Waypoints can help address this problem by reducing the horizon of the learning problem for BC, and thus, the errors compounded over time. However, waypoint labeling is underspecified, and requires additional human supervision. Can we generate waypoints automatically without any additional human supervision? Our key insight is that if a trajectory segment can be approximated by linear motion, the endpoints can be used as waypoints. We propose Automatic Waypoint Extraction (AWE) for imitation learning, a preprocessing module to decompose a demonstration into a minimal set of waypoints which when interpolated linearly can approximate the trajectory up to a specified error threshold. AWE can be combined with any BC algorithm, and we find that AWE can increase the success rate of state-of-the-art algorithms by up to 25% in simulation and by 4-28% on real-world bimanual manipulation tasks, reducing the decision making horizon by up to a factor of 10. Videos and code are available at https://lucys0.github.io/awe/Comment: The first two authors contributed equall

Fast Object Learning and Dual-arm Coordination for Cluttered Stowing, Picking, and Packing

Robotic picking from cluttered bins is a demanding task, for which Amazon Robotics holds challenges. The 2017 Amazon Robotics Challenge (ARC) required stowing items into a storage system, picking specific items, and packing them into boxes. In this paper, we describe the entry of team NimbRo Picking. Our deep object perception pipeline can be quickly and efficiently adapted to new items using a custom turntable capture system and transfer learning. It produces high-quality item segments, on which grasp poses are found. A planning component coordinates manipulation actions between two robot arms, minimizing execution time. The system has been demonstrated successfully at ARC, where our team reached second places in both the picking task and the final stow-and-pick task. We also evaluate individual components.Comment: In: Proceedings of the International Conference on Robotics and Automation (ICRA) 201

Would humans without language be apes?

The bedrock of comparative psychology of cognition, especially where nonhuman primates are concerned, rests on Darwin's famous account according to which continuity would be the main trait leading from the animal to the human mind. This idea was popularized through the statement in which Darwin postulated only quantitative differences between humans and the other species, namely "the difference in mind between man and the higher animals, great as it is, certainly is one of degree and not of kind" (Darwin, 1871, p. 128)..

Does Handedness for Prehension Predict Handedness for Role-Differentiated Bimanual Manipulation During Infancy?

The clearly observable behaviors that identify infant hand-use preferences make the development of this sensorimotor form of lateralization a valuable model for evaluating the development of other forms of lateral asymmetries of function. The current study examined the relation of individual patterns of development of handedness for reaching for objects (prehension) to the emergence of handedness in role-differentiated bimanual manipulation (RDBM). RDBM requires each hand to perform different, but complementary, actions on one or more objects. Hand-use reference for reaching for and grasping objects was assessed in a sample of 85 infants from the period of 6- to 11-months of age using a validated handedness assessment that consists of a series of presentations of 34 common infant toys. At 11 and 14 months, hand-use preferences for RDBM were assessed while the infants were involved in semiplay activity in which they were presented with a series of 13 toys (20-40 s for each presentation). Results revealed no significant relationship between prehension handedness and handedness for RDBM. However, multi-level modeling of the prehension data revealed interesting developmental changes in prehension handedness that can only be identified by using monthly sampling intervals with longitudinal methods

Predicting child handedness from measures of infant and toddler handedness

Cascade theory states that the development of hand preference for a simple action early in infancy will influence subsequent development of hand preference for more complex actions. To evaluate cascade theory, this study analyzed the relation of preferences across three age periods: infancy (6-14 months old), early toddlerhood (18-24 months old) and the preschool period (at 5 years). The infant’s manual preference for acquiring objects was assessed monthly across the 6-14-month age period and preferences were determined using a latent class model. This was compared to their manual preference for role-differentiated bimanual manipulation (RDBM) assessed during the 18-24-month age-period and finally these two preferences are compared to hand preference for RDBM at 5 years and differences in speed between hands when performing a one-handed peg-moving task that is commonly used to assess handedness at 5 years of age. In all three comparisons, the classifications of hand preference significantly agreed with each other in a kappa analysis and failed to significantly disagree with each other when analyzed with a McNemar-Bowker test of symmetry. At age 5, the peg-moving task scores of the groups showing a preference earlier in development were significantly different from each other. The results are discussed in relation to the predictions of cascade theory

A lateral bias in the neuropsychological functioning of human infants

Using my published and unpublished research, a description of the development and functional significance of infant hand-use preferences is presented. Although the character of the infant's handedness will vary with the development of manual skill, the majority of infants maintain stable preferences throughout the 6- to 14-month age range. As with adult handedness, right-handedness predominates in infancy. Infants without stable hand-use preferences show delays, when compared to infants with stable hand-use preferences, in the development of several sensorimotor cognitive skills. Both maternal- and infant-generated experiences contribute to the development of handedness. Given evidence of limited interhemispheric communication during the 1st year, infant handedness can contribute to the development of the functional specialization of the cerebral hemispheres