The effect of friction on the usability of touchpad

To investigate the degradation of the touchpad usability by surface wear, the touchpad with new, worn, plastics and paper surfaces are examined in terms of performance and frictional response. It is found that the friction coefficient of the surface affect the usability. It is concluded that the major factors controlling the friction was surface roughness. It is also found that friction coefficient is affected by the difficulty of the task. The reasons for this is the human tendency to be cautious, he/she try to reduce the load to be precise. Then the load dependence of friction coefficient results in high friction. The other reason is mental sweating, which will be increased when the task is difficult.

► Performance and frictional behavior of four different touchpad surfaces are investigated.
► Higher frictional coefficient degraded the usability of touchpad.
► The friction coefficient increased with decreasing roughness or load, except for paper.
► Difficult task will end up with higher friction because of the cautiousness required for difficult task induces softer touch.
► Difficult task cause stronger stress then mental sweating, which increases the friction.