## 1 Introduction
In addition to the previous considerations, we should take into account that neuroscience and advanced robotics have made available to the rehabilitation area the chance of a massive training and cognitive engagement, which have been demonstrate to be crucial factors for a successful rehabilitation. More precisely, the combination of robotic tasks with virtual reality environments provides an enriched experience that causes a higher focus and attention, novelty, fun and challenge, that all together maximize the cognitive engagement, thus stimulating child's active voluntary participation and, most importantly, neuroplasticity [16]. Indeed, it has been shown that active participation is more beneficial in promoting the sensorimotor recovery in comparison to the passive training, because when passive motion is predominant, the motor system tends to behave as a \"greedy\" optimiser decreasing the voluntary control of movement and the muscle activation [17; 18]. Besides, it is worth highlighting that neuroplasticity is the most significant factor to consider when trying to design a personalized neurorehabilitation process. Neuroplasticity is the brain's ability to reorganize itself by forming new neural connections as a result of learning in response to new situations or to changes in their environment as well as a mechanism to compensate for brain injury [19]. Up to date, there are interesting findings that show how robotic rehabilitation, besides improving motor performance, is able to promote neuroplasticity and modulate functional connectivity of sensorimotor networks [20]. However, despite those studies have been mainly conducted on the adult population, it is reasonable to assume that children would achieve results not only similar, but even more promising [21]. Indeed, previous studies showed evidence of remarkable ability of children's brain to continue to myelinate and produce new dendritic connections after a trauma, further more than how much it happens in the adult population [22; 23]. Particularly, in children, who suffer from brain lesions acquired during the first stages of life, the neural connections are immature and therefore it predominates the need to habititate their brain during maturation, such as to teach them motor skills by strengthening alternative neuromotor networks [24]. Moreover, children with congenital disorders are not aware of what function they could and should aim at recovering, because they have not fully aware of the benefits of full arm function and of the effects of their impairments. As a consequence, in most of the cases, they do not take rehabilitative program seriously while instead high levels of commitment and motivation need to be promoted to reach success in the rehabilitation process. Importantly, several studies reported that these levels of engagement were elicited and maximized in children by the use of robotic devices, just simply because participants appreciated the game-like environment [25; 26]. Among the greatest potential of robotic rehabilitation lies the possibility to program the robotic device according to different types of control strategies chosen depending on the type and severity of the patient's impairment and on the phase of the rehabilitation treatment. These strategies are called active, passive, assistive and resistive and each of them may be more suitable for each specific clinical case. In more details, in the active strategy, the robot provides no haptic feedback and requires subject's active motion; in the passive mode, the robot simulates therapist's work and passively moves child's arms to help them to accomplish the movement; differently, in the resistive mode, the robot interferes with the child movements opposing forces [27; 28]; finally, in the assistive mode, the robot evaluates child's performance and adjusts the level of assistance accordingly.