## 1 Introduction  
Robot-assisted rehabilitation consists in the use of mechatronic devices that can execute one or more tasks autonomously and can be used to apply rehabilitation protocols with the goal of promoting children's sensorimotor recovery [1]. In this work, we reviewed how robotic rehabilitation has been applied to some specific neurological motor disorders, Cerebral Palsy, Stroke and Acquired Brain Injury, chosen according to their impact, epidemiology and their suitability to exploit the technological advantages. Cerebral Palsy (CP) is a group of permanent movement disorders that appears in early childhood and affects 200 children over 100,000 live births [2]. It is due to non-progressive disorders (such as asphyxia, genetic factors, malformations, cerebrovascular events and placental pathology) that affect the developing fetal or infant brain (up to 3 years of age) causing permanent disturbances in the development of the movement and posture [3; 4]. Perinatal stroke, which occurs between the 20 th week of gestation and the 28 th postnatal day [5], is the most common cause of cerebral palsy with over \(2/3\) of children that had experienced a perinatal stroke also having cerebral palsy. Stroke affects a range of 1.3 to 13 cases over 100,000 children [6]; it can be ischemic stroke, when a blood vessel is blocked, or hemorrhagic stroke, when a bleed occurs in the brain [7]. Acquired Brain Injuries (ABI) occur after birth and are not related to congenital factors; among the possible types of ABIs,Traumatic Brain Injury (TBI) is the most common one, and it is caused by sudden, traumatic physical damages of the brain [8]. It presents an impressive annual incidence among children, with 691 cases over 100,000 [9]. The general feature of these neurological disorders consists in resulting damages to the sensorimotor system, sometimes also accompanied by impaired cognitive abilities. In particular, children with CP present a decreased performance in motor control, muscle weakness, spasticity and they might be affected by partial or restricted muscle weakness (hemiparesis) or paralysis (hemiplegia) on the contralateral side of the body with respect to the brain hemisphere in which the damage has occured [10]. Also functional impairments are observed in children with stroke, who usually present deficits in coordination, dexterity, strength and movement speed on both side of the body, including the unaffected part [11]. Given the negative impact that these sensorimotor deficits have on the child's ability to perform activities of daily living (ADLs), treatment of upper limb impairments is crucial to improve their independence and quality of life. Accordingly, in this work we chose to focus on upper limbs robotic rehabilitation, with no consideration of robotic devices and protocols for lower limbs, although this is an equally relevant aspect of robot rehabilitation that would need a proper independent analysis. Robot-assisted rehabilitation of upper limbs can be performed by means of two distinct classes of devices: end-effector robots, connected to a specific part of the body, and exoskeletons that can be considered as a motorized version of orthotic devices. While exoskeletons are \"worn\" by the users and their activation affects at the same time several joints, in the end-effector devices the user usually grasps the robot handle [12]. Surprisingly, although a wide spectrum of upper limb rehabilitation devices has been developed so far, at least in a preliminary proof-of-concept phase, in the great majority of cases they were specifically intended for adult users, with low possibility to adapt to children's biomechanics, as they do not provide the possibility to make changes in size, weight and forces delivered. Despite this limited number of devices developed for the pediatric population, several studies have shown that their use can offer important opportunities in promoting child's sensorimotor recovery and/or in preventing the progression of the disease [13; 14; 15].