برنامه ریزی فرایند عملیات مونتاژ توسط نقشه برداری یک شبیه سازی مونتاژ مجازی برای عملیات واقعی

Virtual assembly has been widely used in product development. However, virtual operation and actual operation are different in time and space, the simulation of interactive virtual assembly cannot support the assembly operation's process planning directly. In this paper, the solution for assembly operation's process planning is developed based on interactive virtual assembly. According to the solution, interactive assembly operation is used to obtain the actions of operation sequence. The actions are mapped into the data of a real operation action to obtain real operation actions. Then assembly operation cards can be obtained. To support the assembly operation actions obtained through virtual assembly simulation, a product assembly model is proposed. An operation semantic model is used to replace the geometric constraint model of assembly, which contains several ordered geometric constraints and some engineering restriction conditions. To test the solution and the models, one process planning example of an automobile engine is introduced. The results verified the feasibility and the effectiveness of the methods.

Virtual assembly (VA) has been widely used in product development, such as assembly analysis, assembly sequence path planning, assembly process simulation, and assembly operation training. There are two main differences between real assembly and virtual assembly simulation: time difference and geometrical difference. Firstly, there is no corresponding relationship between virtual operation time and actual operation time. The simulation time is affected by the response speed of interactive equipment and simulation software. The actual operation time may depend on tools, weights and sizes of parts and operator's gestures. In addition, the operator's action is not free in actual assembly, because his actions may be restricted by parts’ gravity and the force caused by constraints and collisions between parts and other objects. In an assembly simulation, operators complete the assembly action through inputting parts’ motion parameters without considering the movement restrictions. Some force feedback equipment can provide force feedback, such as the CyberForce. But the equipment cannot restrict the user's movements for the reasons of safety and maximum of feedback force. So we cannot obtain actual body movement elements by assembly simulation. A complete assembly operation process contains operation time, consequence path, and operator's motion. Because of the differences in time and geometry, users cannot obtain a complete assembly operation process directly from the virtual assembly simulation at present. In this paper, we present a solution for assembly operation's process planning based on interactive assembly simulation. The interactive assembly operation simulation is used to obtain operation action sequence. A real factor database of operation action is used to obtain the real operation time. The actions are mapped in a real factor database of operation action to obtain real operation actions. To create the assembly operation's actions from virtual assembly simulation, a product assembly model is proposed. An operation semantic model is used to replace the assembly geometric constraint model, which contains several ordered geometric constraints and some engineering restriction conditions. The above methods are applied in an assembly simulation platform DMSP (Digital Mockup Simulation Platform). A module for creating the assembly semantics in Pro/Engineering system are developed based on PTC proToolkit. An engine's assembly process planning is used to test the methods. The main steps for obtaining an assembly operation process include defining the assembly semantics based on product models in Pro/E environment, assembly operation simulation in virtual environment, forming the assembly consequence and paths, and creating assembly operation process. In the following sections, we firstly discuss the related works and then give the basic workflow for assembly operation process planning based on assembly simulation. The two key points of the solution are respectively discussed in Section 4 and Section 5. A case is given in Section 6.

To support the interactive assembly simulation to obtain an assembly operation process, a solution based on assembly simulation is proposed. The main steps include defining assembly semantics in a CAD environment, obtaining virtual operation actions’ sequence by operation simulation, mapping the virtual operation to real operation actions based on a real operation action factor database and composing the motion actors in the sequence to form an assembly operation action sequence. To obtain the reasonable virtual assembly operation actions, we give an assembly semantic model to express automobile engine assembly operation, which contains geometric constraints, corresponding sequence and some operation conditions in engineering. Then an engine is assembled to test the assembly semantic model solution of obtaining the operation process. The testing results show that the engine assembly semantic model can be easily defined in a CAD environment and can support the interactive operation more quickly and conveniently than those based on geometric constraints. Our future works will be focused on the way to eliminate the incorrect operations during disassembling the virtual operation actions, and to develop more effective algorithms for automatic decomposing the motion actors into assembly action.