Research And Application On Key Technologies Of Network Platform For Open CNC System

Computer numerical control(CNC) equipment is the core part of manufacturing system. CNC technology is moving towards the network trend. Especially, after Germany proposed the Industry 4.0 strategy based on CPS, extensive researches have been carried out in open CNC system network platform, and great progresses have been made in the related technologies. The Nation S&T support plan and major S&T project have listed the open CNC system network technologies as their major subjects. The state-of-the-art of CNC network interface is the coexistence and incompatibility of numerous network access methods. There is no information security for CNC communication. The network function of CNC system has not been fully utilized. CNC information model and communication mechanism, interoperability of networked CNC device, secure communication for NC, sensor data access method are key issues in the domain of open CNC network platform.The main contributions of the dissertation are summarized as follow:1. Research of CNC Communication Mechanism.The introduction of the network changes the management mode of CNC system. Because of the difference access methods of CNCs, it is difficult to utilize the CNC resource. The CNC system has the capability to provide a variety of information related to the process to the outside world. The incompatibility of different CNC system form the information isolated island. This dissertation proposed a CNC communication mechanism, which contains an information model and a protocol. The information model formulates the heterogeneous information. The XML based protocol transports information between different terminals. This mechanism can effectively solve the heterogeneous information problem of CNC network, meet the dynamic information integration needs of production lines, manufacturing enterprise, and form a foundation for further realization of intelligent CNC system. The protocol and information model has been adopted by the National Standard “Electrical equipment of machines- Open numerical control system- Part 6: network interface and communication protocol”.2. Research of software platform of CNC network.In complex manufacturing network environment, CNC systems share local functions on the network. Remote users assemble a net-CNC by combining the function units on the platform. This dissertation proposed a reference model for net-CNC software. All the function units of CNC system is encapsulated in function block,that provide data interfaces and event interface. A net-CNC is composed of connected function blocks. The block-based model provides a safe, effective and fast development solution for distributed applications. An interpolation module and a remote control unit are adopted to test the validity of the model. The CNC software model has been adopted by the National Standard “Electrical equipment of machines-Open numerical control system- Part 5: software platform”3. Research of cyber-security of CNC network.There is lots of sensitive information during the standardization communication process of CNC. All the sensitive information is transported as plaintext message without any security measures. This dissertation proposed a hybrid end-to-end encryption to ensure the cyber security of CNC network platform, to prevent the disclosure of sensitive information and to prevent the illegal operation.4. Research of sensor data access mechanism.Sensor access is one of the research filed of industrial 4.0 based on CPS, CNC system status information collected by the sensor is the base of the intelligent processing correctness. Correct data improve the intelligence of CNC machining, while sensor noises weaken the correctness and accuracy of intelligent applications. This dissertation proposed a sensor access mechanism with Kalman fitter. With a filter parameter estimate algorithm and an anomalistic sensor data identification algorithm, this mechanism enhances data processing accuracy. The fitter algorithm has been experimenting on the spindle temperature measurement of 3-axis machine tool and 5-axis machine tool. The results verified the validity of the mechanism.