# Ergonomic Panel Angles for Kitchen Appliances with Cooker Knobs
## 1 Introduction  
Kitchen appliances used daily, such as slide-in/freestanding ranges, ovens, and cook-tops, come in various types with different forms and designs depending on the product line, brand, and model. The interaction between users and these appliances mainly occurs through the control panel (hereafter referred to as the panel), with two primary control types being widely used. One is the traditional knob panel, consisting of multiple cooker knobs, while the other is the touchscreen panel, which has become increasingly popular due to advancements in touchscreen interface technology. Most kitchen appliances feature one of these two control types, and in the case of multifunctional cooking devices (e.g., slide-in/freestanding ranges) that combine cookops and ovens, both control types may be present. When examining the various cooking appliances currently on the market, it is evident that while there are common design standards for basic interaction methods, such as the operation of knobs/switches (push-to-turn or pull-to-turn operation), each brand adheres to its own unique design principles and philosophies, resulting in different specific design values. For instance, electric induction range panels from brands like GE, Bosch, KitchenAid, Frigidaire, Cafe, Samsung, and LG have been designed at a range of angles, including 0, 15, 60, and 90 degrees. The design parameter values of these panels can significantly impact the ease of operating kitchen appliances. The angle of the panel is a crucial factor that influences usability, including visibility and physical comfort, as well as user preference [1; 2; 3; 4; 5; 6; 7; 8; 9]. Insufficient consideration of usability in panel angle design can lead to several ergonomic issues. Firstly, poorly designed panels can force users into uncomfortable and awkward postures, resulting in discomfort in some body parts like the neck, back, andhands. Over time, this can even lead to musculoskeletal disorders [2; 5; 8; 9; 10; 20; 21]. Secondly, an improper panel angle can adversely impact the viewing angle, making it challenging for users to easily and clearly read cooking temperatures, times, and other settings, and furthermore, compelling them into awkward body positions requiring them to bend their neck, back, or knees. Thirdly, these physical issues (discomfort and poor visibility) can impair users' cognitive performance, increasing response times and the likelihood of human errors. Research has indicated that physical workload can negatively affect mental task performance across various task settings [22; 23; 24; 25; 26]. Unlike many other home appliances, erroneous or improper use of kitchen appliances can cause safety hazards, such as fires [27]. Therefore, designing panels with high usability is essential to reduce user errors and response times. Despite the extensive research on the usability of panels, particularly the angles of panels in digital devices like smartphones and tablets [1; 2; 3; 4; 5; 6; 7; 8; 9; 21; 28], there is a significant gap in the research focusing on their application in kitchen appliances. Only a limited number of regulations and design guidelines [29; 30; 31] address safety considerations for kitchen appliance usage. For example, ANSI Z21.1, the American National Standard for Household Cooking Gas Appliances, prescribes the necessary human factor design considerations for designing knob controls used in gas ranges, stating: \"Any gas valve or energy controlling device intended for use during normal operation and which has a position to shut off the gas to a main burner or the energy flow to a heating element shall necessitate not less than two separate operations to turn on and shall necessitate only one operation to turn off\". While the ergonomics literature [32; 33] includes comprehensive studies on aspects like spatial and movement compatibility and human errors associated with panels, there is a noticeable lack of specific guidelines on panel angles.