Ergonomic effects of HMI design variables in dial-type gearshift manipulation.

This study examined the ergonomic effects of HMI design variables determining the manipulation method of dial-type gearshifts. Eight design alternatives were derived by combining two implementation levels for each of three design variables: P-position engagement method (Rotation, Push), Gear indicator location (Up, Left), and Gear position sequence (RND, DNR). Forty-three participants performed gear-shifting tasks using working prototypes of the design alternatives, during which task completion time, number of extra manipulations, perceived workload, perceived safety, and preference were measured. The results revealed the superiority of 1) Push over Rotation; 2) Up over Left under RND, and Left over Up under DNR; 3) RND over DNR in general, and DNR over RND under Left; and 4) combinations of Push-Up-RND and Push-Left-DNR over other design alternatives. The findings and identified ergonomic design characteristics may inform future gearshift HMI designs that prevent driver confusion/misoperation, thereby enhancing driving performance and safety.