# Usability Test for an Over-Ground Walking Assistance Robotic Device Based on the Mecanum Wheel
## 4 Discussion
Lower satisfaction among patients with stroke seems to be attributable to a lack of intuitiveness, non-user-centered control systems, and difficulty in putting on and adjusting devices. In-depth interviews also revealed recurring concerns from patients regarding the difficulty in changing direction or delays in stopping when intended. Therapists generally rated operability and functionality more favorably, possibly due to their greater familiarity and adaptability. In particular, it is important to note the difference in perspective between the two groups of participants. While physical therapists did use the devices during testing, their feedback likely reflects a clinical evaluative standpoint--considering how the device would perform in rehabilitation practice--rather than purely personal comfort or ease. In contrast, the stroke patients' feedback stems from direct, personal use as end-users with mobility impairments. This difference may better explain why therapists reported smaller drops in satisfaction for operability and convenience; they could adapt to the device's interface or judge it acceptable for clinical use, whereas patients experienced more immediate challenges (e.g., difficulty with controls or discomfort) that lowered their ratings. This study was the first usability evaluation conducted for the commercialization of OWAR-MW, assessing user satisfaction from the perspectives of stroke patients and physical therapists. Accordingly, despite the differing viewpoints of the two groups, a single questionnaire was applied to provide a common evaluation framework; however, this approach may have oversimplified the unique concerns of each group. In future studies, tailored questionnaires or separate rating scales for different stakeholders could better capture the nuances of each group's experience. Additionally, according to previous research, to maximize the contribution of assistive technology to enhance the independence and quality of life of individuals with disabilities, it is essential to actively incorporate user feedback during the development phase through a user-centered design approach [16; 17; 24]. Thus, the future development of the OWAR-MW must emphasize user-centered design by improving the precision and responsiveness of motion tracking, simplifying donning and adjustment procedures and enhancing the intuitiveness of the user interface. Another notable finding is that the quantitative (satisfaction survey) and qualitative (in-depth interviews) results of this study showed consistent interpretations. Survey data (Table 2) indicated that among stroke patients, the largest drops in satisfaction scores with OWAR-MW--compared to COWAR--were in items related to directional changes, in-place rotation, and stopping control, suggesting that the safety and responsiveness of the device in dynamic conditions require particular attention. Similarly, interview findings (Table 3) revealed recurring concerns about delayed actuator response and low motion detection sensitivity, which explain the observed dissatisfaction in control and movement synchronization. The lack of intuitive operation and harness-related discomfort--especially due to restrictive thigh straps--were also repeatedly highlighted in interviews, aligningwith the lower convenience scores among patients. These integrated findings emphasize the need to refine OWAR-MW's sensing precision, simplify the control interface, and enhance physical comfort to ensure its viability in clinical practice. This study has some limitations. First, the sample size was small, restricting the generalizability of the findings. Second, this usability test was based on a single-session trial and, therefore, did not capture long-term adaptation, experience, or training effects. Potential changes in user satisfaction, fatigue, and adverse effects due to repeated clinical use warrant further studies. Third, the evaluation relied on subjective surveys and interviews; therefore, individual perceptions and experiences might have influenced the results.