Study On Open Architecture CNC Based On Model Driven Development Method

In the 21st century, manufacturing is confronted with fast and changeable market environments: the greatly shortening of the cycle of products coming into the market, diversification and individualization of the user's requirements, which undoubtedly bring on unprecedented pressure and competition to manufacturing. Numerical control machine tools as the key equipments of manufacturing are determining the level of the manufacturing of our country to a certain extent. The Computer Numerical Controller (CNC) is the central control system of the machine tool, whose comprehensive performance is directly affected and even determined by CNC. While the manufacturing industry is facing keen competition and pressure, the fast progress of science and technology, globalization of economic development bring new opportunity and challenge too. So, this dissertation aims at researching and developing a new generation open architecture CNC with the latest technology of computer software and hardware to change the predicament of existing closed-structure CNC. According to the research on the architecture of Unified Modeling Language (UML) and Modeling theories, this dissertation presents one Object-Oriented CNC Model Driven Rapid Development Process combined on the traditional software iterative lifecycle model. The software development of CNC is divided into four stages: analyzing, design, implementation and testing, according to this process. Taking the manual operation of CNC as an example, using real-time embedded-system modeling tool Rhapsody?, this dissertation introduces the concrete application of Model Driven Development Method in CNC software development in details. This process can be used to the development of the other controller, which adopts the principal and subordinate structure too. The first time application of Model Driven Development Method brings abstract layer of software development from traditional code layer up to the model layer, so that the developer can be absorbed in the specific domain problems instead of cockamamie program codes. It can also test and verify the system function on the model layer. The codes generated automatically from UML model are based on the real-time framework technology and can execute on the target platform efficiently and can change with the UML model synchronously. So this method not only solves the existing disjointed problem between the traditional system model and system implementation but also reduces the iterative lifecycle and guarantees the software quality. Using Model Driven Development Method, this dissertation presents some approved unit UML models such as motion controller, auxiliary equipment controller, numerical control code inspector, numerical control code interpreter, etc. Then an open architecture CNC UML model is acquired through the integration testing of the unit UML models. It can be reconfigured according to the user's requirement dynamically, can be used in different target platforms and has software modularity. The CNC UML model can be highly reused by dint of modeling elements such as newly-increased composite class, state diagrams inheritance, ports and required (supplied) interfaces with more accurate semanteme in UML2.0. For example, when the model is used in Win98/2k or Windows CE.NET target platform, only two classes associated with hardware can't be reused. The extension and maintenance of the system are also available on the model layer. Based on the real-time modeling and schedulability analysis theories, we have analysed the schedulability of the relevant CNC real-time tasks on the CNC model layer. The method is as followed: first, labels the relevant real-time attributes (QoS: Quality of Service) of CNC tasks using the stereotypes and tag values, defined in the UML real-time profile. Then we can execute the schedulabiltity analysis by the real-time schedulability analysis tool RapidRMA?, which associates the CNC UML model through the VBA (Visual Basic Application). The analysis result can be fed back to the CNC UML model automatically. The Schedulability of the real-time system can be easily analyzed in multi-phase, such as analysis, design, and system realization using this method. This method also solves the traditional disjointed problem between function and performance in real-time system. This dissertation introduces the process of real-time schedulability analysis of CNC multi-task, taking the CNC automata as an example. Finally, the CNC UML model has been verified on the CNC testbed developed by ourselves. This testbed consists of embedded single board computer (SBC), motion control card and IO card based on DSP. The real-time communication is implemented through the PC104 bus among the SBC, motion control card and IO card. The operation system running on the SBC is Windows CE.NET real-time operation system. Comparing this testbed with the traditional CNC hardware platform, it has the obvious advantages on hardware modularization, reuseability, reliability, real-time performance and cost, etc.