Age-dependent differences in learning to control a robot arm using a body-machine interface

Abstract

Body-machine interfaces, i.e. interfaces that rely on body movements to control external assistive devices, have been proposed as a safe and robust means of achieving movement and mobility; however, how children learn these novel interfaces is poorly understood. Here we characterized the learning of a body-machine interface in young unimpaired adults, two groups of typically developing children (9-year and 12-year olds), and one child with congenital limb deficiency. Participants had to control the end-effector of a robot arm in 2D using movements of the shoulder and torso. Results showed a striking effect of age - children had much greater difficulty in learning the task compared to adults, with a majority of the 9-year old group unable to even complete the task. The 12-year olds also showed poorer task performance compared to adults (as measured by longer movement times and greater path lengths), which were associated with less effective search strategies. The child with congenital limb deficiency showed superior task performance compared to age-matched children, but had qualitatively distinct coordination strategies from the adults. Taken together, these results imply that children have difficulty learning non-intuitive interfaces and that the design of body-machine interfaces should account for these differences in pediatric populations.

Controlling a robotic arm for functional tasks using a wireless head-joystick: A case study of a child with congenital absence of upper and lower limbs

“…One popular approach is to use dimensionality reduction techniques like principal component analysis (PCA) to extract the most relevant movement directions for control. While this technique can accommodate different movement repertoires, they have only been implemented for controlling one or two degrees of freedom [7], [9]; furthermore, the mapping between the motion of the body and that of the assistive device can often be non-intuitive [20]. A more recent approach - the Virtual Body Model (VBM) [21] - is more intuitive for control of high DOFs because of the pre-defined mapping between the body and device DOFs but relies on a nearly full range of movement in the torso.…”

“…First, a limitation of our approach is that the ‘burden of learning’ is all on the user. This may be especially challenging for children, who show deficits relative to adults in learning such interfaces [20], [22]. One way to improve this is to use either an adaptive interface that adjusts to the user [23], [24], or use a shared control framework so that the autonomy of control can be shared between the human and the machine [25].…”

“…Our main participant was a 14-year old male born with tetra-amelia (congenital absence of all four limbs) - see Fig 1a. He had participated in two previous studies with our group which involved position control of a cursor [19] and 2-DOF velocity control of the end-effector of a robotic arm [20]. In the current study, he used his head as a joystick to control the robot arm as shown in Fig 1a.…”

Controlling a robotic arm for functional tasks using a wireless head-joystick: A case study of a child with congenital absence of upper and lower limbs

“…Our main participant was a 14-year old male with congenital absence of all four limbs-see Fig 1a. He had participated in two previous studies with our group which involved position control of a cursor [20] and 2-DOF velocity control of the end-effector of a robotic arm [21]. These prior studies involved the control of these devices using shoulder and torso movements.…”

Usability evaluation of mechatronic system by primary school children

“…Embodied interactions and body posture have also been analyzed to detect children's engagement and social interactions with robots [12,13]. In another case [14] the interaction of children was analyzed with the help of gestures that showed a good percentage of acceptance of the new means of communication. The children were found to have great motivation for the activity and the ease of interaction was assessed as very positive [9].…”