Study on Size Coding Identification of Manual Rotary Knob

Size coding is a common coding method of assigning different size to a manipulation device during design process. It is widely used in industrial product design and human-machine interface design that need to quickly identify or distinguish alignment devices. In this study, the effects of size coding of manual rotary knob on identification rate and identification time were studied experimentally. The identification correct rate and identification time for paired manual rotary knobs with different diameters were obtained. The results showed that when using the size coding to identify the manual cylindrical rotary knob devices, the knobs with a diameter difference in 4 mm could be distinguished correctly by 100% of female and more than 96% of male. The knobs with a diameter difference in 6 mm could be distinguished correctly by all of the participants. The increase of the knob diameter reduced the number of people who could distinguish the difference in size of 2 mm. The identification time increased with the increasing of the knob diameter. The larger the difference between the two knobs diameter paired, the higher the identification correct rate and the faster the identification time. Female’s identification time was significantly faster than male. The results are helpful to understand human’s identification limit of the dimension, as well as the gender difference at dimension identification ability. The data could provide reference for product ergonomic design related with dimensional coding of manual rotary knobs.