# Perspectives and Challenges in Robotic Neurorehabilitation
## 2 An Overview of Robotic Devices for Neurorehabilitation
### Robotic Neurorehabilitation for the Lower Limb
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**Exoskeleton** & & & & & \\  
* This work compares the effects of three gait rehabilitation interventions: Partial body-weight support gait rehabilitation training with treadmill and robot-aided gait assistance with G-EO Systems and Lokomat. Flex. Flexion; Ext. Extension; Abd. Abduction; Add. Adduction; Dors. Dorsiflexion; Plant. Plantarflexion. \(\chi 2\) indicates that the actuated DOF is the same for the two legs. Abbreviations for the diseases under examination—SCI: Spinal Cord Injury; MS: Multiple Sclerosis; TBI: Traumatic Brain Injury.  
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Table 4: _Cont._A custom-made battery pack is located next to the motherboard and it guarantees up to five hours of continuous operation. There are two electric motors per each leg (hip and knee) and they allow for joints' flexion/extension in the sagittal plane. As a result, Twin's actuated DOFs are two per leg, the hips and the knees. The total number of DOFs is three per leg, if we consider the ankle that, however, is passive. Twin's main feature is its complete modularity that allows the device to be assembled and disassembled easily and quickly. Eight electromechanical connectors make it possible to achieve this goal. These connectors realize a dual function: They can both bear the structural mechanical load and serve as an electrical interface between the different parts of the exoskeleton. This facilitates and decreases the time to don and doff Twin. Currently, a position control has been implemented to assist subjects with complete Spinal Cord Injury (SCI). The IMU installed in the central control unit estimates the pitch and roll angles of the trunk. As soon as the trunk exceeds a certain degree of tilt angle in the sagittal plane (this value depends on the patient's degree of impairment and it is set by the operator in agreement with the therapist), the motors automatically perform a step. Thus, by detecting trunk inclination, it is possible to determine the patient's intention to move. Furthermore, it is possible to set other variables, such as the step length, the clearance that is the maximum distance between the foot trajectory during the swing phase and the ground, and the duration of the gait cycle. A mobile GUI allows all these parameters to be set and monitors the events in real-time. During Twin-aided locomotion assistance, the use of crutches is required. Moreover, another Twin functionality supports the patient's sitting/standing up movement. In this case, the exoskeleton fully performs the movement, meaning that the patient's intention to move is not read as in the walking scenario. A remote command from the GUI sends the trigger to start sitting or standing up. In this operative modality, different parameters are used with respect to the walking modality. Indeed, there is the possibility to set: The inclination value of the trunk during  
Figure 2: Fronto-lateral view of the Twin exoskeleton (**A**), lateral view (**B**) with a particular focus on the hip joint (motor and electromechanical interface), fronto-lateral view (**C**) of the pelvis module highlighting the pelvis structural element and the backpack containing the battery, and posterior view (**D**). Written informed consent was obtained from the subject depicted in the panels. the phase of sitting/standing up, the total duration of the sitting/standing up procedure, and the pause between the two events. In the current state, Twin is undergoing further modifications in the control strategy for neurorehabilitation applications that will target stroke survivors.