Objectives  Since the visual cone maintenance visibility analysis method based on the visual field of the human eye cannot quantitatively evaluate visibility and visual field occlusion, an improved visibility evaluation model is proposed.

  Methods  First, the plane field vision model of the object is established according to the visual field cone of the human eye in order to determine its visual range. Combined with distance and volume of the object, the visual range is evaluated. Next, a line-of-sight model from the human eye to various parts of the object is built to judge the intersection of line-of-sight and other objects, and identify the shielding of the objects. Finally, the evaluation results are quantified. The improved maintenance visibility analysis function module is realized in DELMIA software by carrying out secondary development in a VC++ environment with CAA+RADE.

  Results  In the maintenance visibility verification of a welding workstation, the improved method can effectively evaluate visibility, quantify the evaluation results and quantitatively evaluate the occlusion of objects.

  Conclusions  The improved method greatly improves the comprehensiveness and rationality of visibility analysis in complex equipment maintenance.