## 4 Discussion  
The main concept of the developed rehabilitation robot is to close the loop to provide continuous feedback to enhance neuroplasticity in stroke recovery. [PERSON] et al. (2017) proposed two conceptual loops in brain modulation. One is \"brain-state dynamics\" loop and another is the \"task dynamics\" loop. The task dynamics loop involves motor-sensory feedback between the brain and the environment (object). In the design and development of the proposed robot, the main idea was to directly deliver visual information to the robot using the mounted camera instead of decoding occipital electroencephalography, while securing accurate visual information and actuating the robot according \begin{table}
\begin{tabular}{l l} \hline \hline
**Raised Issue** & **Potential Solution** \\ \hline - Need for feedback at the end of range while & - Insertion of pressure sensors for tactile feedback. \\ grasping to avoid over-actuation. & - Inevitably \\ - Contour and fitting of the hand part needs & - Individualized manufacture of the hand part with \\ improvement. & three-dimensional printers. \\ - It would be better if active assistive exercise function & - Insertion of force sensors to recognize active \\ was included. & movements of the patients. \\ - Switch pad should be more simple and easier to use & - Object recognition and consequent robot movement \\ and control, especially when considering elderly & could be automatized using image-based machine \\ patients. & learning algorithm. \\ - The size of the robot needs to be reduced and & - Design modification necessary when developing \\ redundant cables should be minimized. & final prototype for mass production and also medical \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Issues and potential solutions of the proposed distal upper limb rehabilitation robot from the usability test. Figure 6: Usability test results for an image-processing based distal upper limb rehabilitation robot are shown for four categories of respondents. The scores are in a 7-point Likert scale, with 7 points representing most satisfactory or safe and 0 points for least satisfactory or unsafe. Patient data include responses of both chronic stroke patients and their long-term caregivers. to the user-intent at the same time, therefore, closing the loop for the motor-visual-sensory feedback. It was also expected to promote patient motivation, which is an important factor for securing high repetition using the robot [38], because the rehabilitation robot system uses real objects instead of virtual interfaces, such as computer monitors or tablet displays. In this research, we applied [PERSON]'s approach for a development and usability test of a new product [39]. The usability test results showed high scores for interest, motivation, and safety issues, but relatively low scores for difficulty, comfort, and expectance of improvement. Because this system did not use a computer display as the main interface, using real objects instead, which may be used at home or at the bedside, the respondents replied that these features were interesting and that the robot may help patients to be motivated for the therapy. The response from the patient group showed lower scores in most of the categories except safety. The patients responded that the device was not appropriate for their stroke recovery stage; however, they also commented that the device would be very useful for patients that are not able to move the distal upper limb. The survey results showed that learning how to use the robot was difficult especially in responses by therapists and patients. A short training time may have affected this result. However, it is definite that the user interface and the control method should be improved in the next step of development for pertinent use in clinical studies or commercial use. The main issues from the free comments were that the gripping was not highly secure, and that the task was limited due to the low degree of freedom.