Human-centred principles for the design of shape- changing tangible user interfaces

Many shape-changing interfaces (SCIs) have been developed in recent years as a type of tangible user interface (TUI). These are helpful in some contexts but have fewer usability features. The reason behind their limited features might be the lack of design guidelines for TUI, especially SCI. In this paper, we review frameworks that have been proposed for SCIs and relate them to a theory of affordance, ultimately constructing an SCI equation that would serve as a useful tool to improve the usability of upcoming SCIs