A comparison of two command language user interfaces for a CNC machine

Abstract

Computer numerically controlled (CNC) machines are common pieces of equipment in manufacturing plants. In recent years, CNC‐user interfaces have been evolving from CNC command languages to menu‐based and direct‐manipulation interfaces. However, there have been few efforts to evaluate CNC‐user interfaces and to develop design strategies to improve their usability. An experiment is reported comparing the effectiveness of two user‐interface layouts for a CNC‐milling machine. One user‐interface layout was a simulation of a popular interface for a CNC‐milling machine. The second layout was designed after analyzing the command language characteristics, the button grouping, and the finger movements required to operate the first interface. Then, both layouts were compared in terms of time to complete a set of benchmark tasks, number of errors generated, and users' preferences. Four factors were manipulated: (1) users' level of expertise. (2) layouts, (3) tasks, and (4) trials. It was found that both groups of subjects completed the tasks faster using Layout 2 rather than Layout 1. Similarly, subjects' responses to a questionnaire indicated that Layout 2 was preferred over Layout 1 in almost all of the usability categories studied.