The method of predicting the maintenance time of mechanical products based on Virtual Prototype

Aim: To predict the mechanical product maintenance time is difficult in the situation of lack of physical prototype or similar products’ statistics in stage of design Method: According to the theory of time accumulative estimation method, a product maintenance time prediction method framework based on virtual prototype was constructed, which described the prediction process. The virtual maintenance environment which contains virtual prototype, virtual human and maintenance tools was developed. The virtual human’s position and posture information during the maintenance process was obtained by implementing VBScript language. Result: Basic maintenance motions that constitute the whole maintenance process were classified into 4 categories: body movement, upper limb movement, grasp/replace and operation. Based on MODAPTS (Modular arrangement of predetermined time standard) method and virtual maintenance simulation, corresponding time prediction methods for each categories were proposed. Discussion: Take a maintenance dissassembly and assembly task of engine as an example, through the comparison between the measured actual maintenance time and predicted time of several methods, feasibility and effectiveness of proposed method are verified

Hybrid Reconstruction and Evaluation of 3D Model of Equipment Parts for Virtual Maintenance System

The research and application of reverse engineering technology are more and more extensive, but its process is still not fully mature. Aiming at the complexity of equipment parts and the diversity of accuracy requirements, the method of hybrid reconstruction and evaluation of 3D model of equipment parts for virtual maintenance system is illustrated. The general process is given. Taking the two-stage bevel gear worm reducer as the research object, the research on three-dimensional scanning, data processing and model reconstruction is carried out. This paper focuses on the reconstruction process and methods such as regional division, solid model construction based on maximum outer contour, creation of basic surface, patch fitting and so on by taking the bevel gear in the reducer as an example. Finally, 3D comparison, 2D comparison, cross-section accuracy and size of the reconstructed solid model are evaluated. The results show that the hybrid reconstruction method has strong adaptability and high efficiency. Reverse modeling and forward design are organically combined to give full play to their advantages, and the hybrid reconstruction method can effectively reverse the original design intention of the product and improve the parameterization ability of reverse modeling. It can meet the requirements of different precision models developed by virtual maintenance system, structural wall chart and atlas, multimedia and so on.

Maintenance Accessibility Evaluation Method based on D-H Model and Comfort in a Virtual Maintenance Environment

In virtual maintenance, the most widely used accessibility evaluation method is to use virtual human reach envelope surface to judge and evaluate accessibility. 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 a method of accessibility envelope surface construction are proposed. 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). In order to facilitate the application of this method in virtual environment, a method of accessibility envelope surface construction is proposed. Firstly, the reachable points are generated by Monte Carlo simulation based on the D-H model. Secondly, the accessibility envelope surface is composed of the outermost random reachable points. Finally, the comparison experiment with the reachable envelope provided by DELMIA in virtual environment shows that the proposed method is more accurate, meticulous and objective. Based on this method, an accessibility evaluation tool has been developed in CATIA and has been applied in some scientific research institutes.

A capsule-based collision detection approach of irregular objects in virtual maintenance

Purpose Virtual maintenance simulation is of great importance to help designers find and avoid design problems. During its simulation phase, besides the high precision requirement, collision detection must be suitable for all irregular objects in a virtual maintenance environment. Therefore, in this paper, a collision detection approach is proposed based on encapsulation for irregular objects in the virtual maintenance environment. Design/methodology/approach First, virtual maintenance simulation characteristics and several commonly used bounding boxes methods are analyzed, which motivates the application of encapsulation theory. Based on these, three different encapsulation methods are oriented to the needs of simulation, including encapsulation of rigid maintenance objects, flexible maintenance objects and maintenance personnel. In addition, to detecting collisions accurately, this paper divides the detection process into two stages. That is, in the first stage, a rough detection is carried out and then a tiny slice space is constructed to generate corresponding capsule groups, which will be redetected in the secondary stage. At last, several case studies are applied to illustrate the performance of the methodology. Findings The automatic construction algorithm for bounding boxes can be adapted to all forms of objects. The number of detection primitives are greatly reduced. It introduces the reachable space of the human body in maintainability as the collision search area. Originality/value The advantages of virtual maintenance simulation could also be advantageous in the industry with further studies. The paper believes this study is of particular interest to the readers of your journal.

Application of a Novel Virtual Maintenance System: Digital Enterprise Lean Manufacturing Interactive Application-Ergonomics for Integrating Human Factors into Maintenance Processes Design of Carrier-Based Aircraft

The novel virtual maintenance system has been used to explain ‘how’ DELMIA-Ergonomics (DE) to go from a reactive, maintenance in security procedures, which will be proactively integrated into every step of the research and development design cycle process. DELMIA software has been widely applied in carrier-based aircraft department as the platform, promotion of virtual prototype pre-maintenance technology in carrier borne design and daily inspection/maintenance is introduced, interactive virtual maintenance flow, the virtual scene structuring, the processes of maintenance simulation of virtual actual working conditions, predictable maintainability analysis/valuation technology based on DELMIA software are expounded. The worldwide trend to popularize gradually increasing use of taking DELMIA software in maintenance technology applications is a carrier-based aircraft for gaining interest. DE has become a means to improve carrier-based aircraft performance.