Research On Quantitative Calculation Of Visual Factors In Virtual Assembly System

During the process of product development,there is no doubte that assembly is one of the most important key link, it is also the most important part of human and material consumption,and it has important influence on product quality, production cycle and production cost. Through the virtual assembly technology can build almost real assembly environment.Based on the realistic assembly simulation, the assemblability of parts, the reasonability of assembly spatial arrangement, the reachability of assembly operation and the comfort of operator are verified. Using the virtual assembly environment to evaluate the product assembly performance and assemblability in the early product design stage, find out the potential collisions during assembly process and the design deficiencies, and then prompt the designers to find and solve the problems as early as possible. Thus, it will optimize product assembly performance, improve the quality of products, shorten the development cycle and enhance the market competitiveness.At present, there is little evaluation of man-machine engineering in the evaluation of the assembly of the products. In most of these evaluations, the majority of these evaluations are qualitative evaluation, and lack of quantitative evaluation. Human as the main participants in the production and assembly activities, directly or indirectly affects the efficiency of the whole product assembly. There are many factors affecting the assembly activities of operators, such as equipment, tooling equipment, process factors etc. However, we tend to ignore the human factors. In the evaluation of the assembly, the human-machine factor includes many aspects, such as visual factor, comfort factor and energy consumption.In this paper,based on the virtual reality software 3ds Max, a quantitative study of the visual factors in human-machine factor is carried out. According to the physiological characteristics of human,visual vertebral is established on the basis of anthropometry.Based on the coordinate transformation, the local coordinate system is set up to facilitate the calculation.And produce a uniform distribution of the line to simulate the human eye.Calculate the percentage of visibility part of the parts to be assembled.Calculation examples are given,and evaluate the visual accessibility quantitatively. By calculating the results, we can adjust the assembly space, the distribution of the components, the assembly position in the initial stage of the product assembly, so that the visual accessibility can reach the best state, reduce the physiological and psychological fatigue, decrease the assembly error rate and production cycle, in this way the production efficiency can be maximized.At the same time, we improve the quantitative calculation method of visual factors.The optimization method of visual cone angle is given to reduce unnecessary computation and improve the accuracy of calculation.It is also suggested that when the assembly parts are not in the best viewing area because of the space layout or the assembly location, the method of establishing the visual vertebral body in the operator's largest visual area is presented.