Cheng Rui Zhang

A STEP-NC programming system for prismatic parts

To comply with STEP-NC (ISO 14649), a new paradigm for NC programming, many computer systems involved in NC manufacture are required to reshape in both functionality and structure. This paper reports a feature-based NC programming system for prismatic parts to be machined using STEP-NC machine tools. The proposed system consists of three functional modules, i.e. a feature-based modeler, a process planner and a part program generator. The modeler provides a graphical environment for the part model, which is created by adding manufacturing features on a 2.5 D sweep primitive shape. The process planner determines which operations are to be performed for the features, generates workingsteps and then produces a reasonable workplan. Finally both the geometrical and the process information are passed to the part program generator to form a complete ISO 14649-compliant file. The proposed system is demonstrated through the generation of the STEP-NC part program for an example part, and major issues such as the feature-operation mapping and the workingstep sequencing etc are also addressed in this paper.

Solutions for Interpreting STEP-NC Based Part Program

STEP-NC is a new CNC data interface proposed to replace ISO 6983, and has been partly formed into the draft international standard (ISO 14649). In this paper, the STEP-NC-based part program is analyzed, and the general methodology and tools for STEP-compliant application development are introduced. Then a framework for STEP-NC interpreter is proposed based on the SDAI method and the implementation solutions are presented. The EXPRESS compiler is used to convert the milling schema into C++ classes, and the information is extracted from the file in aid of data access tools. The said interpreter, which is fundamental to STEP-NC based machining, is also implemented with supporting tools in the ST-Developer environments. It is used to read the STEP-NC file into ROSE working form, and then extract and organize the manufacturing information in an object-oriented way.

Development of an Ontology-Based and STEP-Compliant Intelligent CNC System

STEP-NC (ISO 14649) is a newly developed and feature-based machine tool control language for CNC controller. In contrast with conventional G&M code (ISO 6983), this new data model could almost transmit all the designing and planning information for machining parts through CAD&CAPP&CAM to CNC. However, STEP-NC is feasible but not enough to support some intelligent actions such as self-planning, self-learning, decision-making, etc. A complete and well-structured knowledge base is urgently needed to be established to support CNC intelligence. The main work of this paper is focused on two fields: i) An extraction, presentation and utilization mechanism for ontology-based machining knowledge is implemented. ii) A novel framework for STEP-Compliant and knowledge-base supported intelligent CNC controller is proposed.

Development of Industrial Ethernet Windows Driver for Motion Control System

An industrial Ethernet based motion control system is presented in the paper. The first slave node in the line topology is responsible for the precise cyclic communication, and it will reduce the real-time requirement on the main controller. The communication protocol is implemented as Windows NDIS protocol driver, and provides higher priority than normal user mode application. In addition, the development environment and process are also discussed, through which the developer can debug the system software at a single computer in both simulated mode and real mode.

A New State Estimator of PMSM Using Adaptive Extended Kalman Filter

This paper presents a new permanent magnet synchronous motor (PMSM) drive technique using adaptive state estimator for high-performance motion control to estimate the instantaneous speed, position and disturbance load torque. In the proposed algorithm, the model reference adaptive control (MRAC) method is incorporated to identify the variations of inertia moment, and the identified inertia is used to adapt the extended Kalman filter (EKF), which is an optimal state estimator to provide good estimation performance for the rotor speed, rotor position and disturbance torque with low precision quadrature encoder in a random noisy environment. In addition, the disturbance–rejection ability and the robustness to variations of the mechanical parameters are discussed and it is verified that the system is robust to the modeling error and system noise. Simulation and experimental results confirm the validity of the proposed estimation technique.

An Agent-Based Framework for STEP-NC Controllers of CNC Machine Tools

STEP-NC is a promising data interface for CNC, by which a comprehensive set of information regarding the product to be manufactured can be conveyed for the first time to the shop floor. In this paper, the new data model is briefly overviewed and analyzed. Then functionalities and considerations as for implementation of STEP-NC controllers are identified, followed by a conceptual framework proposed for such STEP-NC controllers for a new breed of CNC machine tools featuring autonomy and cooperation. The proposed system is constituted with a planning agent and a machining agent. The former is designed to take responsibility to cooperate with the external systems, to prepare all the data needed in machining and schedule them into unit tasks, while the latter, as one of the planning agent’s local control modules in light of an excellent combination of functionality and reliability, controls the machine tools adaptively. The working mechanism of the whole system is also introduced with an illustration of the operational flow.

Study on the Simulation System Based on STEP-NC

This paper presents a simulation system based on STEP-NC that can verify STEP-NC program and demonstrate the running of STEP-NC system (CNC system based on STEP-NC). NC Programs used in the STEP-NC system are in XML format. The overall architecture of the system which consists of feature extraction module, graphical modeling module, movement modeling module, feature library, simulation drive module and user interface is established. Some key technologies to implement simulation system are discussed in details. The simulation system shows great potential to the development and popularization of STEP-NC system.

On CNC Machining and Part Program Preprocessing Based on STEP-NC

STEP-NC is a new CAM/CNC interface and an extension of STEP into numerical control machining. It has been partly formed into draft international standard (ISO 14649) and is expected to replace ISO 6983 in the near future. In the first section of this paper, the STEP-NC data model is analyzed and those parts that are relevant to NC milling process are abstracted. Then issues involved in NC part machining based on STEP-NC paradigm are discussed including NC programming and the machine control. Based on the analysis, a prototype system is outlined and partly developed with libraries and software tools in ST-Developer environment to interpret the part program into internal data format and to assist the shop floor level planning. Finally the user interface of this system is introduced.

Research on Remote Monitoring System of Loom Workshop for Different Yarn Materials

The implementation of remote monitor in workshop can improve the production efficiency and contribute to the production management. In this paper, a remote monitoring system of air-jet loom workshop based on B/S structure is designed. The system adopts wireless networking mode in hardware and mainly consists of data acquisition module, database service module and Web service module in software. The data acquisition module is implemented with Visual C++. MySQL is chosen as the database management to design database service module. The Web service module is developed on the platform of asp.net and it is released on the IIS platform of cloud server, so that users can visit the Web site through browser clients. Different yarn materials need to be configured with different parameters. The loom computer can send requests to the cloud server for parameters. The system can analyze the types of yarn materials according to the requests and configure different parameters. This will be quite convenient for workers to change yarn materials.

A Tangential Tracing Control Algorithm for NC Glass Cutter Machine

To ensure the scribe-wheel is always forward along the tangent direction of the cutting path, a new planning algorithm is proposed for the cutter shaft rotating control. The short linear segments used for approximating the cutting curve are separated by the equipartition conditions. For the satisfied ones, the angle between the adjacent segments is linearly interpolated and the cutter shaft rotates without stopping the machine. Otherwise, it needs to stop and rotate the shaft. The experiments show that the deviation error of scribe-wheel is small, and the error existing period is short, which proves the algorithm can achieve the scribe-wheel tangential tracing and satisfy the accuracy requirements while cutting complex shapes.