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Reconciling scene realism with interactivity has emerged as one of the most important areas in making virtual reality feasible for large-scale CAD data sets consisting of several millions of primitives. Level of detail (LoD) and multi-resolution modeling techniques in virtual reality can be used to speed up the process of virtual design and virtual prototyping. In this paper, we present an automatic LoD generation and rendering algorithm, which is suitable for CAD models and propose a new multi-resolution representation scheme called MRM (multi-resolution model), which can support efficient extraction of fixed resolution and variable resolution for multiple objects in the same scene. MRM scheme supports unified selective simplifications and selective refinements over the mesh. Furthermore, LoD and multi-resolution models may be used to support real-time geometric transmission in collaborative virtual design and prototyping.

Structure optimization of Hardness Testing Device (HTD) based on virtual design is proposed here. The purpose of the HTD is to obtain hardness properties of accessories. Since the creation of the previous HTD, a few problems have been experienced during testing. In the present work, improvements in both equipment design and automation control have been made. A realistic digital analysis is generated by combining automated and interactive approaches to evaluate the capability of the device with simulation software ADAMS and AMESim. Theoretical analysis is taken into account to obtain numerical results close to reality. The approach and the conclusions should be useful for composite structures design. The improved design of HTD reduces the number of costly physical prototypes, improves design quality and reduces product development time.

Kinematic simulation in virtual environment is the key technique of product performance evaluation. Based on graph theory, the paper gives the integrity knowledge expression of product motion model, including the topological structure, motion dimension and driver information. It builds a solver of kinematic analysis for planar linkage interactive-oriented, which based on auto-identifying of Assur groups and auto-generating of kinematic analysis routine by operating labeled adjacency matrix. A new method of kinematic simulation for virtual prototyping is put forward based on the kinematic mapping of pseudo-linkage. The achievements have been applied to the kinematic simulation of internal-combustion engine, punch and crusher.

The air-suction seed metering device is the most commonly used seed meter in the domestic market. However, it has a high missing-seeding rate when used to sow non-circular seeds, as the seeding stops unpredictably, causing an entire line of missing-seeding. By studying the metering device's structure, a new type of air-suction compensating precision metering device was designed and presented in this paper. The metering device is installed with a detection device as well as an intelligent seeding compensation device. It thus has real-time control over the seeding case, and can both offset missing-seeding and promptly respond to seeding stoppage. All of these features can ultimately lower the missing-seeding rate and improve the quality of seeding effectively.

Virtual design is an essential part of the folding carton design in packaging combination. In order to achieve the ideal result of the design, packing box type from 2D to 3D interface changes, in the process of transformation, by correction and adjustment of design parameters. In this paper, we analyzed the combination of triangles and non-triangular packaging carton design and molding, and given the appropriate combination of shaping design examples. In view of the virtual design application in the folding cartons combination, to find the different shapes of the structure of the forming and packing assembly in stack tile forming method of virtual design. According to the influence of the packaging combination modeling show, production and cost estimates, find out the optimal design. Not only for the convenience of the designer create a more beautiful and practical folding carton packing, but also to shorten production time packaging design, to save the cost of packaging design production, to reduce unnecessary loss of time, thereby to improve the production efficiency.