Maintenance accessibility evaluation method based on D-H model and comfort in a virtual maintenance environment

Maintainability, especially for complex products, is a very important general quality characteristic. Physical accessibility is the primary element in maintainability design. Up to now, VR (virtual reality) technology-assisted maintainability evaluation, analysis and design, called virtual maintenance, has become the mainstream and achieved some results. In virtual maintenance, the most widely used accessibility evaluation method is to use virtual human accessible envelope to judge and evaluate accessibility. However, this method can only give two kinds of evaluation results: accessible and inaccessible. Moreover, the envelope lacks sufficient data and theoretical support, so the precision and accuracy of evaluation method need to be improved. In this paper, a parameterized accessibility evaluation method is proposed and the corresponding evaluation models and tool are created. Firstly, to objectively describe the movement of human body, a 6-joint and 5-link D-H (Denavit–Hartenberg) link model is established from the waist to the fingertip of the human body, and the ranges of 10 degrees of freedom and angles related to accessibility are determined according to ergonomics. Then, comfort is introduced to refine the accessibility evaluation, and a multi-level accessibility evaluation system based on comfort is constructed according to RULA (the rapid upper limb assessment). Thirdly, in order to facilitate the application of this method in virtual environment, accessibility envelope models and accessibility evaluation tool are created based on the proposed method. Finally, compared with RULA and the accessible envelope provided by DELMIA, respectively, the results from virtual and real environment of the comparative experiment show that the proposed method and tool are accurate, more precise and more efficient.