Analysis of natural finger-press motions for design of trackball buttons

Abstract

This study analysed natural press motions of the index, middle and ring fingers for ergonomic design of the positions and surface angles of the left, middle and right trackball buttons. Finger motions of 26 male participants for naturally pressing the trackball buttons were recorded after the participants adjusted the trackball buttons to their preferred locations for comfortable pressing. The natural positions of the finger pulps formed a symmetrically rainbow-shaped reach zone for the fingers. The natural press angles of the fingers’ motion trajectories to the vertical reference line ranged from 14.2° to 20.5°, suggesting an 18-degree surface from the horizontal line for the trackball buttons. Regression formulas (adjusted R² = 0.90 ± 0.07 and mean squared error = 8.55 ± 7.52 mm) were established to estimate the natural positions of finger pulps from hand segment lengths and joint angles for a population having different hand sizes from this study.

Relevance to industry

Relevance to Industry

Trackball buttons designed based on the natural press motions of fingers can provide users with a low physical workload and a high comfort level. This study analysed the natural press motions of the index, middle and ring fingers for designing the positions and surface angles of trackball buttons.

Keywords:

• Natural finger motion
• natural motion trajectory
• motion analysis
• button position
• button angle

Additional information

Funding

This research was jointly supported by LIG Nex1 and the National Research Foundation (NRF) of Korea Grant funded by the Korean Government (NRF-2016R1C1B1008150, NRF-2017R1D1A1B03036081, NRF-2018R1A2A2A05023299).