Abstract: This paper briefly describes the background, concept, and characteristics of open CNC systems. It proposes the guiding principles, structure, and main forms of open CNC system development, and discusses the overview, challenges, and future development trends of open CNC systems both domestically and internationally. Keywords: Open; CNC system; Modular [b][align=center]The Open NC System HAN Quan-li, MA Hong-wei, YANG Lai-xia (Xi'an Institute of Science & Technology, Shanxi Xi'an, 710054, China)[/align][/b] Abstract: Based on the original definition and characteristics of CNC, this paper discusses the basic rules for its development, structure, and types. It also describes the direction and development trends of CNC systems in the future. Key words: Open; NC System; Modular 1 Background of the Emergence of Open CNC Systems With the rapid changes in technology, market, and production organization structure, the development of CNC technology faces many new challenges. New machining demands are constantly emerging. The demand for CNC systems is growing for rapid, high-performance, and customer-oriented modularity and hardware/software reconfiguration capabilities, with significant improvements in cost and time required for such reconfiguration. This aims to gradually reduce manufacturers' dependence on control systems, substantially lower maintenance and training costs, and move away from the closed design of traditional CNC systems to adapt to future task- and order-oriented production models, making underlying production control simpler and more effective. The current model, where CNC system suppliers provide the main unit and manufacturers integrate their patented technologies, eliminates the need for manufacturers to disclose any of their technical secrets to system suppliers. Therefore, seeking a new development model for control systems that effectively addresses these issues has become essential. CNC system manufacturers, integrators, and users all desire "open controllers" that allow for the free selection of various components of the CNC system, such as CNC devices, drive devices, servo motors, and application software, and the ability to combine these components in a standardized and simple manner. This has led to the development of Open Number ODNTROL Systems (ONC). 2. Current Status of Open CNC Systems 2.1 Overview of ONC in the United States The National Manufacturing Development Center (ONC) has conducted research in three aspects: (1) a new generation of controllers; (2) low-cost controllers; (3) open modular structure controllers. 2.2 Overview of ONC in Japan The Open CNC System (OSE) Research Association announced its achievements in 1996: (1) proposed the ONC reference model and transformed it into a banquet model; (2) developed an interface system based on personal computers; (3) proposed and developed the OSEL language; (4) developed control interfaces and language processors. 2.3 Overview of ONC in the European Community The Open Automatic Control Project (OSACA) has now entered its third phase. The main achievements are: (1) defined the basic specifications of neutral (i.e., not dependent on any manufacturer) open CNC systems; (2) formulated a neutral unified structure that can be used for CNC systems, robots, programmable controllers and unit controllers; (3) developed the first batch of demonstrative application software modules. 2.4 Overview of ONC in China During the Eighth Five-Year Plan period, China successfully developed two CNC platforms and four basic systems, namely Zhonghua I, Aerospace I, Lantian I, and Huazhong I, utilizing bus-based, modular, open, embedded, and multi-channel software and hardware structures. Currently, most of them are still in the closed stage and there is still a certain gap from the international level. 3 Basic characteristics of open CNC technology 3.1 Concept of ONC Referring to the relevant provisions of IEEE on ONC, we believe that: a true ONC must provide the ability for different applications to run on the system platform; provide dynamic reconfiguration tools with functions; and provide a unified and standardized application interface. ONC has both an open interface and an open core. ONC has the following characteristics: (1) Openness. It provides a basic platform for a standardized environment, allowing different software and hardware modules from developers to intervene; (2) Portability. Different application modules can run on system platforms provided by different manufacturers. Meanwhile, the system software can run on hardware platforms with different characteristics; (3) scalability, the addition or subtraction of its functions is only manifested in the loading and unloading of specific functional modules; (4) substitutability, functional modules with different performance and reliability can be replaced, and will not affect the normal coordinated operation of the system; (5) operability. Standardized interface, communication and interaction model. Therefore, ONC analyzes and implements the control function of the CNC system from a completely new perspective, emphasizing the development towards modularization, platformization, toolization and standardization. 3.2 Guiding ideology of ONC development 3.2.1 Make the most of personal computer software and hardware technology to ensure that personal computers have reliability and computing power, and that hardware is standardized. The running software has many functions, such as a friendly interface, graphic display, dynamic simulation, CNC programming, fault diagnosis, network communication, etc. Use program development tools and use general programming languages ​​to compile software modules to replace the original modules, so that manufacturers and users can add functional modules with their own unique technical know-how. 3.2.2 Modularization The modularization of the CNC system is based on the logical analysis of each functional element, realizes the standard connection between modules, and realizes plug-and-play. 3.2.3 Dynamic Configuration System To achieve more flexible configuration and a more user-friendly operation, ONC can dynamically configure the system while it is running. This is achieved based on the dynamic generation of the system topology, including several steps such as defining constituent elements, parameterizing the functions of constituent elements, and organizing the information flow between constituent elements. 3.2.4 Portability ONC requires that the defined data structure naming conventions and user interface appearance facilitate implementation on different system platforms. In terms of software, it adopts a layered design or client-server model for application design, placing hardware-related parts at the lower level for easy replacement and portability. 3.2.5 Scalability ONC enables users or secondary developers to securely and effectively integrate their software into personal computer systems to form their own dedicated systems. There are two methods: one is to fix the internal structure of modules and reserve interfaces for inserting user-specific software; the other is to provide user-defined API (Application Program Interface) functions and programming specifications for users to create dedicated modules. 3.2.6 Encourage industry participation in the open atmosphere of ONC development needs, encourage enterprises to actively participate in research work, and encourage enterprises to take the initiative to participate in or lead relevant research. 4 Structure of Open CNC System According to the aforementioned definition, its structure is divided into two parts: a unified system platform and application software modules composed of various functional structural unit objects (ARCH1TECTURE OBJECT). 4.1 System Platform The system platform consists of system hardware and software. The hardware is determined by functional requirements. The software is divided into three parts: (1) the system core, such as the operating system, communication system, real-time status configuration system, etc.; (2) optional system software, such as database system, graphics system, etc.; (3) the standard application interface is f(AI 1), which is the only way for system functional unit objects to enter the system platform. It implies the actual implementation of the services provided by the system platform, making the software and hardware independent, and at the same time, different functional unit objects have a unified interface on various types of platforms. The system core is the basis for the operation of the control system. The internal communication of the system refers to the ISOADSI model and follows the message-oriented communication mechanism. The system communicates with external superiors based on standard protocols such as MAP and CN-MA; communication with lower-level systems uses standard driver interfaces and time-domain buses. Real-time configuration is a key aspect of ONC development. The key to system platform development lies in the establishment and application of object-oriented software technology, software refactoring technology, communication technology, and interface specifications. 4.2 System Reference Structure: This precisely describes the relationships between functional elements and functional modules, the relationships between modules, defines the behavior and attributes of modules and functional elements, and the interface between modules and functional elements and the system platform. It ensures that functional modules from different manufacturers work on different platforms. The reference structure's openness, flexibility, and the effectiveness of control functional units guarantee the independent and coordinated control functions. The key to establishing the system structure is, based on the analysis of the original system functions and implementation, to apply group technology, object-oriented technology, and other tools to decompose functions, extract the commonalities and specificities of control functions, and specify the behavior of functional modules and functional elements and their interoperability interfaces. Personal computers are the main development path for ONC, roughly divided into two types: one is a computer as the main body, plus the main control part of the control system; the other is a control system as the main body, plus relevant computer parts. Both are currently widely used. There are three main types of personal computer numerical control systems: (1) control board inserted into the computer; (2) computer board inserted into the control system; (3) software numerical control. 5 Problems and development trends of open numerical control systems The main purpose of ONC development is to solve the contradiction between complex and changing requirements and the fixed framework of the control system. To achieve a flexible, compact and inexpensive control system. From a technical point of view, the tasks of ONC development are roughly five aspects: control; sensing; interface; actuator; software. 5.1 Control technology The controller consists of three parts: CPU, I/O, and memory. In terms of personal computer ONC, in order to improve its intelligence, it is required that: (1) manufacturers can freely select motors and amplifiers according to the torque power of the product; (2) the number of input points and processing speed of the programmable controller (PLC) can be arbitrarily selected according to the product; (3) the interpolation functions formed by free curves and free surfaces are grouped; (4) the scope of standardized software is further expanded; (5) there are various applicable CPUs; (6) for free surface processing, registers can be added when there is a large amount of data processing. 5.2 Interface Technology: Interface technology specifically includes motion interfaces, human-machine interfaces, and network interfaces. The ONC personal computer further requires networking, requiring: (1) standardized information functions and operations; (2) acceptance of CAD/CAM/CAE information from enterprises; (3) acceptance of production information database information; and (4) connection with the CAD/CAE/CAT systems in the factory. 5.3 Sensing Technology: ONC development requires intelligence, unmanned operation, and integration, possessing a complete sensing system with high sensitivity. 5.4 Execution Technology: ONC development requires the development and research of various actuators, such as high-speed cutting spindles, high-speed moving motors with pneumatic (hydraulic) static bearings, high-precision positioning motors, etc. 5.5 Software Technology: ONC development requires: (1) the application of high-level languages ​​to describe information; (2) concise description of free curves and free surfaces; (3) meeting data representation requirements at different levels; (4) dedicated macro commands having a certain degree of universality; and (5) active application of network functions. The challenges facing ONC include: consistent human-machine interface (MMI); software-based controllers; emphasis on the openness and application of real-time control (RTOS—YEAL TIME OPERATION SYSTERM); development from open MMI and limited kernel openness to fully open external kernel; and network functionality. Future trends in ONC development include: developing high-quality, advanced, marketable, economical, rational, and open CNC systems in five aspects: control technology, interface technology, sensing technology, execution technology, and software technology; utilizing new machining expression languages ​​to simplify design, production preparation, and machining processes; reducing data storage; using 64-bit CPUs to achieve 3D surface machining; further adapting to high precision, high efficiency, and high automation requirements; and achieving networking to further realize unmanned, intelligent, and integrated automated production. 6. Conclusion: The development of ONC is a historical inevitability. Currently, developed countries are conducting intensive research in this area, providing a good opportunity for the development of China's CNC industry. The country should focus on supporting research in this field to ensure China's continued competitiveness in the international market. References [1] Wu Zuyu, Tong Jinsong, Lu Zhiqiang. Prospect of core technologies for flexible automation - open CNC system. DIE and TECHNOLOGY, 1999, (3): 94-96. [2] Zhang Maoliang, Xie Xuhui, Li Shengyi. Development of open CNC technology. Electromechanical Engineering, 1999. (4): 66-69. [3] Chen Xunjie. New trends in the open development of CNC systems for machine tools in the world today. Grinding Machines and Grinding, 1997, (7): 5-6. Click here to download the original text