Understanding the ergonomic constraints in designing for touch surfaces

While most current interactive surfaces use only the position of the finger on the surface as the input source, previous work suggests using the finger orientation for enriching the input space. Thus, an understanding of the physiological restrictions of the hand is required to build effective interactive techniques that use finger orientation. We conducted a study to derive the ergonomic constraints for using finger orientation as an effective input source. In a controlled experiment, we systematically manipulated finger pitch and yaw while performing a touch action. Participants were asked to rate the feasibility of the touch action. We found that finger pitch and yaw do significantly affect perceived feasibility and 21.1% of the touch actions were perceived as impossible to perform. Our results show that the finger yaw input space can be divided into the comfort and non-comfort zones. We further present design considerations for future interfaces using finger orientation.