Thresholds for Dynamic Changes in a Rotary Switch

Switches are everyday objects that interface humans to many functionalities and influence our perception of the machinery that they are attached to. This study is aimed at a better understanding of the perceptual attributes of switches. Specifically, the perceptual thresholds for dynamic changes in a rotary switch were evaluated in two experiments using an adaptive procedure. Exp. I measured human’s ability to detect the presence of a random noise superimposed on a sinusoidal torque vs. angular position profile. The detection thresholds were found to be in the range 1−3% of the peak torque. This high sensitivity was interpreted as being consistent with the existing literature in that humans are more sensitive to stimulation at high frequencies than that at low frequencies. Having established the importance of switch dynamics in its perception, Exp. II measured detection thresholds for sinusoidal torque variations with spatial frequencies ranging from 2.8° to 180°. Average thresholds varied from 0.37 to 26.17% of the average torque (30 N⋅mm) over the aforementioned spatial frequency range. These experiments provide quantitative results on our ability to detect dynamic events in a rotary switch. They shed new insight on the design and specification of rotary switches.