# Ergonomic Panel Angles for Kitchen Appliances with Cooker Knobs
## 5 Conclusions  
This study provided empirical insights into the influence of panel angle on visibility, physical comfort, and user preference ratings. The findings demonstrated that panel angle significantly affected all three measures, emphasizing the need to consider usability factors, such as visibility and physical comfort, alongside aesthetic and mechanical design elements when designing panels. The findings suggest that a panel angle ranging from 30 and 90\({}^{\circ}\) (with an optimal range of 45 to 60\({}^{\circ}\)) from the horizontal is recommended for knob panels. This study presents several practical and theoretical implications: first, the recommended panel angle range in this study was derived from considerations of visibility and physical comfort. These findings are expected to help users maintain comfortable visibility while reducing physical discomfort during panel use. Moreover, the results could contribute to preventing musculoskeletal disorders that may arise from repetitive/prolonged usage. Second, the study concludes that an ergonomically optimal panel angle should be presented as a range rather than a single fixed value. Offering an adjustable range is more beneficial for accommodating a broader variety of users than adhering to a \"one-size-fits-all\" approach. This aligns with the principle of \"designing for an adjustable range\" [32; 43], which suggests that equipment and facilities should be designed with adjustable dimensions to accommodate individual users. Given variations in body size due to factors like gender, age, and geographical region, it is recommended to either provide adjustable panel angles or design panels tailored to specific user groups. Third, the appropriate/optimal panel angles identified in this study are expected to enhance the usability of panel operations, which in turn could positively affect user acceptance of the product. User acceptance is closely related to a user's intention to use a product or system [44]. Therefore, the findings could be applied to increase user acceptance or user intention to use, potentially boosting sales for kitchen appliance manufacturers. Some limitations of this study are recognized, along with recommendations for future research: firstly, this study focused solely on subjective ratings of visibility, physical comfort, and preference. In future research, including metrics like task completion time, response time, and error rate is recommended to provide a more comprehensive under-standing of how panel angle affects user performance and error rates. Furthermore, incorporating tools such as electromyography, motion capture analysis, and the Borg CR10 scale could offer deeper insights into physical comfort. Secondly, this study only considered six specific panel angles (0, 15, 30, 45, 60, and 90\({}^{\circ}\)). Future research could benefit from experiments where participants explore the optimal/acceptable panel angle range for visibility, physical comfort, and preference across the entire continuous range of 0 to 90\({}^{\circ}\). This \"self-selected/user design\" approach would be valuable as it considers the full range of possible panel angles and could yield additional/new insights [45; 46; 47; 48]. Lastly, while this study focused on panel angle as the primary design variable affecting usability, other factors, such as the spatial arrangement of knobs, knob shapes (e.g., straight knobs vs. round knobs), and the labeling method for power levels, are also important variables that could influence usability. A more comprehensive study including these factors would likely result in more meaningful and in-depth analyses. Conceptualization, M.S. ; methodology, M.S. ; formal analysis, M.S. and D.B. ; investigation, M.S. and D.B. ; resources, M.S. ; data curation, M.S. and D.B. ; writing--original draft preparation, M.S. ; writing--review and editing, D.B. and S.A.; visualization, M.S. ; supervision, D.B. ; project administration, M.S. ; funding acquisition, M.S. All authors have read and agreed to the published version of the manuscript.