Accessibility Evaluation Method based on D-H Model and Comfort

In virtual maintenance, the most widely used accessibility evaluation method is to use virtual human entity accessibility envelope surface to judge and evaluate. However, this method can only give two kinds of evaluation results: reachable and unreachable. There is not enough data and theoretical support for the construction of envelope surface, and the precision and accuracy of evaluation need to be improved. In this paper, a parameterized accessibility evaluation method and the construction method of accessibility envelope surface are proposed. Firstly, a 6-joint and 5-link Denavit-Hartenberg (D-H) link model is established from the waist to the fingertip of the human body, and the range of 10 degrees of freedom and angles of the 4 joints are determined according to ergonomics. Then, the reachable points are generated by Monte Carlo simulation. The accessibility envelope surface is composed of the outermost random reachable points. Then, comfort is introduced to refine the accessibility evaluation level, and a multi-level accessibility evaluation system based on comfort is constructed according to the rapid upper limb assessment (RULA). Finally, the comparison experiment with the reachable envelope provided by DELMIA in virtual environment and real environment shows that the proposed method has better evaluation accuracy and precision. Based on this method, an accessibility evaluation tool has been developed in CATIA and has been applied in some scientific research institutes.