Current Situation, Trends and Countermeasures of Open Control System
The consequence of market globalization is that the competition is unprecedentedly fierce, which requires manufacturers to have strong market adaptability. Therefore, the market demand for manufacturing systems suitable for small and medium batch processing with good flexibility and versatility has gradually surpassed the demand for large single functions. The needs of the manufacturing system. This trend has led to the emergence of a new concept, modular, reconfigurable, and scalable hardware and software systems, which are open control systems. Not only does this system adapt quickly and economically to new processing needs, but it also gives manufacturers the possibility to integrate their technology with any third-party technology or product. Next page Slope Protection Mesh,Ball Fence,Handrail Ball Fence Steel Wire Co., Ltd. , http://www.nssteelwire.com
1 Foreign research trends
The concept of an open control system has emerged in the 1980s. As early as 1981, in order to reduce the dependence of arms manufacturing on Japanese control systems, the US Department of Defense began a program called "Next Generation Controller (NGC)" and established the "National Manufacturing Science Center (NCMS)". Its main purpose is to develop and advance detailed analysis and specifications for a new generation of open control systems. As a follow-up to NGC, the US Department of Defense launched the OASYS project, which aims to build and install eight controllers and test them in six different locations. Since then, many related research projects have been launched in various countries around the world. The most influential ones are the US OMAC, the European OSACA and the Japanese OSEC.
1.1 OMAC plan
In order to solve a series of problems encountered in the development of the automobile industry in the United States, Chrysler, Ford and GM started a project called "Open, Modular Architecture Controller (OMAC)" in 1994. s plan. The goal of the program is to reduce the investment cost and maintenance costs of the control system, shorten the product development cycle, improve machine tool utilization, provide "plug and play" software and hardware modules and efficient controller reconstruction mechanism, simplifying new technologies to the original Systematic integration makes the system easy to update, keep up with the development of new technologies, and adapt to changes in demand. The main motivation is to inform controllers and technology development groups about the needs of controller users, especially in the automotive industry, in order to understand and better understand the needs of users so that they can purchase products that meet their requirements in the market.
Since the members of OMAC are the users of the controller and not the developers, this determines its nature and purpose, which in turn determines that its productization and practicalization cannot be fast. In fact, the American industry believes that OMAC is a concept, not a controller or standard. OMAC itself is aware of this issue and is currently working with OSACA and others.
1.2 OSACA Program
OSACA (Open System Architecture for Control within Automation System) was jointly initiated by 22 controller developers, machine tool manufacturers, control system integrators and scientific research institutions in the European Community in 1990 and officially obtained in May 1992. EU recognition is included in the EU ESPRIT-III project plan. This was actually the first phase of OSACA-I, which ended in 1994 and completed the development of the OSACA specification and application guidelines. Its second phase of OSACA-II (ESPRIT 9115) was completed in April 1996. It mainly completed the development of a standard, common software module and a common OSACA system platform for its system platform in accordance with the OSACA specification, and established a five-axis manufacturing system environment. Used to debug, verify, and extend the various specifications of the previous phase. The third phase of OSACA began with IDAS OSACA (Information Dissemination and Awareness Action) in January 1997. The plan lasted for 18 months to promote the OSACA ideas and the technical achievements of the preliminary work. At the same time, in order to establish an international standard, it is in contact with relevant institutions of Japan and the United States. One of OSACA's goals is to make itself a universal international standard in the field of automation, so it began to cover the entire field of automation, and invested a lot of manpower and material resources.
1.3 OSEC
Japan's "Controller Open System Environment (OSEC)" was jointly established by Toshiba Machine Company, Toyota Machine Works and Mazak's three machine tool manufacturers, and Japan's IBM, Mitsubishi Electric and SML Information Systems. Its purpose is to establish an international standard for factory automation (FA) control equipment. Based on the CNC system reference model proposed by the Japan International Robotics and Factory Automation Research Center (IROFA), OSEC proposed an open architecture. Implemented IROFA's reference architecture and added functionality for custom and differentiated products.
2 Preliminary study of open control system
With the support of the National Natural Science Foundation of China and other units, we conducted theoretical and practical research on open CNC systems.
2.1 Modeling of open control systems
Because object-oriented software development technology integrates functional abstraction and data abstraction, it better implements software scalability, polymorphism, and makes software easy to modify. We use object-oriented method to model CNC system software. It is described and implemented in three levels: system, control unit and basic class. Make CNC software assembleable and easy to expand.
The basic class is the result of fine-grained decomposition of the numerical control system function and is the smallest unit that constitutes an open system. The basic classes form the class system of object-oriented NC software. The basic class with standardized interfaces is called a software chip.
A control unit is a software entity that consists of a series of functionally related basic classes that perform certain functions. Control units can be nested.
The system is a type of CNC system software consisting of a series of control units. It can contain one or more objects of a control unit or base class. Figure 1 is an object-oriented partitioning model of numerical control software functions. Because the object-oriented method directly maps real-world physical objects to software objects, and encapsulates the data (properties) and operations of the objects themselves, it is intuitive and easy to understand.