KnobSlider: design of a shape-changing device grounded in users' needs

In this paper, we explore how to combine the advantages of physical knobs and sliders by using shape-change in order to transform one into another on-demand. By doing so we merge the benefits of both input devices: knobs enable relative angular input with dynamic gain and require little space; sliders require more space but enable absolute linear input and can be grouped to be simultaneously adjusted and monitored. Our initial contextual interviews unveil situations where such dynamic device could be particularly beneficial for professionals such as sound and light engineers as they require tangible devices and high flexibility. We then present the 9 alternative designs of KnobSlider, a shape changing input device that can switch from a knob to slider and vice-versa. We propose a set of 11 requirements for such a shape-changing device and conducted a systematic analysis of our 9 designs against our 11 requirements. This work is a first step toward building a high-fidelity KnobSlider.