# Ergonomic Recommendations for Range of Control Panel Angle of Touchscreen Kitchen Appliances
###### Abstract  
Control panels for kitchen appliances have been designed in various forms and with different design parameter values. Among these design parameters, the panel angle is one of the most important factors influencing the usability and user preference. However, few studies have been conducted regarding the panel angle effects in the context of kitchen appliances. There are only a few safety-oriented regulations or guidelines for kitchen appliance design. Therefore, in this study, the effect of the control panel angle of touchscreen kitchen appliances on their usability was empirically investigated for providing appropriate ergonomic recommendations. A total of six panel angles, namely, \(0^{\circ}\), \(15^{\circ}\), \(30^{\circ}\), \(45^{\circ}\), \(60^{\circ}\), and \(90^{\circ}\), were employed in the experiment in consideration of the design parameter values used in existing slide-in/freestanding ranges. Three usability evaluation measures, namely, visibility, physical comfort, and preference, were employed. For each of the six panel angles, 20 participants performed temperature/power-level setting tasks and then subjectively rated the panel angle in terms of the three measures. The following major findings were obtained: (1) the control panel angle affected the scores of all three measures; and (2) when considering visibility, physical comfort, and preference comprehensively, the panel angle ranges \(15^{\circ}\)-\(42^{\circ}\) and \(15^{\circ}\)-\(19^{\circ}\) were recommended as the appropriate and optimal ranges, respectively. The findings of this study may be helpful in the ergonomic design of touchscreen panels for kitchen appliances, which can improve the usability of these panels and reduce human errors and response time in emergencies. control panel angle; kitchen appliances; touchscreen panel; usability evaluation; ergonomic design +
Footnote †: journal: Applied  
studies have examined the usability of panels in the context of kitchen appliances. Very few regulations or design guidelines [20; 21; 22] focus on safety while using kitchen appliances. In the ergonomics literature [23; 24], studies on compatibility (spatial/movement compatibility, etc.) and human error related to panels have been conducted in detail; however, no guides for panel-related design variables such as the panel angle have explicitly been mentioned. The touchscreen panels of modern kitchen appliances usually have panel angles close to 0\({}^{\circ}\) or 90\({}^{\circ}\) (e.g., those of Bosch, KitchenAid, Frigidaire, Cafe, and Dacor electric induction ranges), which are mainly determined based on aesthetic factors and ease of mechanical design rather than usability. The following problems may occur if usability is not sufficiently considered in determining the panel angle. First, users are highly likely to be in uncomfortable and awkward postures when operating improperly designed panels, which may cause physical discomfort in their necks, waists, and fingers/wrists. They may even develop musculoskeletal disorders upon repeated and prolonged use of poorly designed panels [2; 5; 25; 26; 27; 28; 29; 30; 31; 32; 33; 34; 35; 36; 37; 38; 39; 40; 41]. Second, because the panel angle directly affects the viewing angle at which the user looks at the panel, it may be difficult for users to check the cooking temperature, time, and other options easily when the panel angle is not appropriate. In addition, inappropriate panel angles may cause users to stand in unnecessarily awkward positions, such as bending the neck, waist, and knee. Third, there is a possibility that the aforementioned physical factors (physical discomfort and low visibility) negatively affect the cognitive performance of the users, resulting in a longer response time or human error. Multiple studies have examined the effects of a physical workload on the performance of concurrent mental tasks in different contexts. [PERSON] and [PERSON] [42] found that physical workload and fatigue decreased the cognitive task performance of registered nurses.