## 4 Discussion
In regard to both robot types, the UIG did not need to take phone calls or use computers with the robot. This may be because they have an intact arm and are older in age than the patients in other disease categories. For the exoskeletons, stroke patients did not require wheelchair control or transfer assistance, as they could manage it with their intact arm or by using a cane. In general, the ratings for importance and necessity for the exoskeleton were higher than those for the external robotic arm. The UIG showed significantly higher necessity for the exoskeleton than for external robotic arms in washing face, brushing teeth, and eating. In the BIG, dressing, moving closeitems, using a purse, switch control, using a computer, eating, making phone calls, writing, and using a smartphone showed higher necessity for exoskeletons. While bimanual ADLs such as hairdressing, handling foods, and dressing showed high scores for both types of robot, the patients with unilateral impairment demonstrated higher demands for using exoskeletons for grooming-related activities, whereas the subjects with bilateral impairments tended to give higher scores to activities necessary for social functioning and interactions. The primary purpose of this survey study was to assess pure potential users' unmet practical demands regardless of technical difficulties; therefore, we assumed that the device would be controlled perfectly by a BMI system. We also assumed that the simpler the robot, the more it would be feasible for patient application, and in order to be simple, the robot should perform limited tasks. The limited tasks should be the functions that the patients would really need, instead of useless functions. After deciding the target function, the design and development process should be focused on how will the robot can assist the ADL function most properly, controlled by user intent as much as possible, without interfering with basic activities. Therefore, the results of this study could also be applied to the robots not controlled by a BMI system. A specific control method or design should be selected on the basis of the target function. Workspace and motion analyses for performing such tasks should be assessed as well [28]. [PERSON] et al. [29] suggested an ICF (International Classification of Functioning, Disability, and Health) based concept in developing and utilizing assistive robots for specific ADLs, which may guide the developmental process in the clinical perspective. Regarding the engineering aspects of the developmental process, [PERSON] et al. [1] reviewed up-to-date existing solutions for the development of upper limb rehabilitation robots regarding applications, type of assistance, design, and control methods. This study has several limitations. First, the number of subjects was not sufficient to generalize the needs of all persons with upper extremity impairments. The subjects in the UIG were relatively homogeneous and representative of chronic stroke patients; however, the BIG mostly consisted of young patients with muscular dystrophy and only five patients with cervical spinal cord injuries, potentially possessing limitations for generalization. However, most previous studies were performed in patients with spinal cord injuries or ALS. Therefore, this study may provide a reference for comparison between different disease entities. Second, most of the participants were not familiar with the concept of a BMI other than the explanation given to them just before the survey. There may have been some difficulties in imagining how it would be with the given technology and functions. If they had known more about BMIs and rehabilitation robots, the survey results would have been more accurate.