Virtual Factory Integrated Manufacturing System for Process Simulation and. Monitoring

Transcription

1 Virtual Factory Integrated Manufacturing System for Process Simulation and Monitoring Zewei Zhou, Yiping Feng, Gang Rong*, Feng Zhu *State Key Laboratory of Industrial Control Technology, Institute of Cyber-Systems and Control, Zhejiang University, Hangzhou, , P.R.China ( iipc.zju.edu.cn) Abstract: A virtual factory integrated manufacturing system combined with system simulation and virtual reality is introduced in this paper. We describe the system architecture and development methodology, provide the working principle of process simulation and monitoring in virtual factory, and then explain the detailed applications of virtual factory integrated manufacturing system. With the visualization and three-dimensional human-computer interaction about process and production data, this platform can provide effective supports on monitoring, control and operation of manufacturing system. Keywords: simulation; integration; virtual reality; intelligent manufacturing systems; integrated plant control 1. INTRODUCTION Virtual reality combined with process simulation and monitoring is one of the attractive research topics in process industry. Virtual reality is a computer system which can create a virtual world, and provide users with the feel as they were right on the scene. Virtual reality system generally has three features (Bridge et al., 2007): immersion, interaction, imagination. Users can wander in the virtual reality environment (Mujber et al., 2004), think and analyze the information perceived, emerge those wanted strategy, then provide feedback to the system to interact with the system and control its process. Since performing experiments on industrial equipments may be expensive and risky, research in the virtual manufacturing system will be very important. CB&I Company in Chicago (USA) had developed the 3D Virtual Refinery and provided intuitive description of material flow in refinery. (Fang et al., 2006) introduced a detailed analysis of the development of dynamic-static hybrid simulation platform and combined dynamic simulation of key units with static simulation of the whole industrial process in the virtual factory laboratory system. (Wu et al., 2006) proposed a virtual factory framework which integrated enterprise-level operation and process simulation. In this paper, we introduce a virtual factory integrated platform, and explain its overall design and architecture. With the combination of system simulation and virtual reality, the virtual factory integrated platform realizes the visualization of both process simulation results and process data and provides effective supports on decision making for process simulation and monitoring in the manufacturing industry. 2. SYSTEM ARCHITECTURE AND DEVELOPMENT METHODOLOGY Virtual factory integrated platform is composed of a database system, a dynamic-static simulation system, and a three-dimensional scene system. Each subsystem can communicate information with others to realize the integration of total platform. According to virtual reality modelling language (VRML) (Ieronutti et al., 2007), we use Autodesk 3ds Max tool to build the three-dimensional models in virtual factory, and use Microsoft Visual Studio C# Copyright by the International Federation of Automatic Control (IFAC) 5219

2 program language to integrate those models to create a virtual environment. Similarly to the human-computer interface mentioned in the reference (Sun et al., 2009), we build a three-dimensional input-interface through which users can set different instructions about scheduling and process control in virtual factory, then put these control parameters into the integrated database system. Meanwhile, dynamic-static simulation system obtains these instructions and runs corresponding simulation models. Then the simulation outputs are saved into the database system. Finally three-dimensional scene system reads these data and visualizes the simulated process of production in the virtual environment, which can augment reality (Reif et al., 2008). And the closed loop simulation architecture about the process simulation of virtual factory integrated platform is illustrated as Fig.1, which shows the system principle. Database system describes the topological structure of simulation models with a series of static data tables, including different devices, units, pipes, streams along with their properties and relationship, and also describes the instructions and simulation result with a series of dynamic data tables. Dynamic-static simulation system is based on mechanistic models and production data, which can realize the production changing process and support for process control system in virtual factory (Mert et al., 2009). And the three-dimensional scene system realizes human-computer interaction and information representation (Soares et al., 2004). In order to show sufficiently the layout of each equipment workshop, the overall design of virtual factory is very important and its 3D scene model is constructed, which can make best satisfaction for users. Therefore, we refer some design standards in petroleum and petrochemical industry, including design specification for site plan in petrochemical engineering and general rule of plant layout design for petrochemical industry. Then we design a virtual factory as shown in Fig.2, which is quite similar to a real factory. In order to realize such a virtual factory integrated manufacturing system, the connection and interaction of information flow among these subsystems is very important, which integrates all the modules as a whole. 3. WORKING PRINCIPLE OF VIRTUAL FACTORY Process simulation and monitoring platform in virtual factory can realize multi-level simulation among different business levels, especially in process control system level and manufacturing executive system level. The working principle and system structure is illustrated as in Fig.3. The objective of the virtual factory platform is to construct a three-dimensional human-computer interface not only for manipulation of simulation process, but also for monitoring, control and decision making for the real-time manufacturing system. Fig.1. Closed Loop Simulation Architecture of Virtual Factory Integrated Platform 5220

3 Fig.2. Virtual Factory Three-Dimensional Integrated Manufacturing System As an integrated platform, each subsystem has its own structure and connects with others in the form of process data and operational instructions. Dynamic-static hybrid simulation system consists of some simulation modules of production process, such as dynamic simulation of unit operations and static simulation of material flow and energy consuming. The simulation models are integrated and manipulated with the interactive control interface. And the simulation result data are transmitted into the integrated database platform, which consists of basic description property data about factory models, process interactive control parameter tables and simulation result statistics data tables. Meanwhile there is an aggregation from real time database (RTDB) to relational database Oracle for the multi-level integrated simulation in virtual factory. Visualization process monitoring platform is designed both for simulation process and real-time production data. The process parameters in Fig.3 represent process measurements such as temperature and flowrate, which are visualized with 3D measurement instruments and control valve in the platform. Since the virtual factory is constructed according to the industrial field of real factory, visualization monitoring platform is quite the same as that in industry field. The procedure diagram for constructing virtual factory simulation platform is shown in Fig.3. Firstly, we analyze and design the virtual factory layout, including plant-wide layout and workshop layout. Fig.3. Process Simulation and Monitoring in Virtual Factory Integrated Platform 5221

4 Then we build 3D models about virtual factory devices to create an interactive 3D virtual factory dynamically and use the texture mapping technology to realize dynamic-static process simulation for augmenting reality. And then we present the varying production process information to create man-machine interaction environment for interactive control. Process monitoring system which consists of process monitoring and fault simulation can also transmit information to integrated database platform and interact with virtual factory simulation platform. Finally there is some feedback information from virtual factory simulation platform, which can improve simulation and control effects by modifying some control parameters. value of temperature or pressure. The flowsheet of FCCU simulation system is illustrated as in Fig APPLICATIONS OF VIRTUAL FACTORY 4.1 Dynamic-Static Hybrid Process Simulation In the virtual factory integrated platform, dynamic-static hybrid process models describe the input-output relational mechanism about process units, which can simulate the real process of the factory. When the production plan or the scheduling instruction changes, the simulation platform would calculate the response and output of the production process and generate a series of production data for further research of the real process. We take Fluid Catalytic Cracking Unit (FCCU) in the virtual refinery for example. Firstly, three-dimensional models of reactors, regenerators, measuring instruments and control valves are established. Then the dynamic mechanistic models of FCCU are built up to implement dynamic simulation. In the human-computer interface, operators can set control parameters and introduce different disturbances, such as change of yield, change of oxygen content in regenerators, change of level and pressure in reactors. Dynamic simulation program get these instruction parameters and start to simulate, then put result into database again. Finally the three-dimensional scene system reads these production data and represents the varying process states of FCCU in a 3D interactive way. We make the reactant bubbles rise or fall according to the production data, which represents the change of level in reactors or regenerators. The color of inner space of reactors or regenerators will change continuously according to the temperature or pressure data, and the different degree of color represents the different numerical Fig.4. Process Flowsheet of FCCU Simulation Model Visualization and representation of dynamic simulation of FCCU is illustrated as Fig.5, which shows representation of temperature, and the different degree of red color means different degree of temperature. When the temperature of reactors is higher, the degree of red color is deeper. And when the mouse on the interactive interface clicks the position of a measuring instrument, the pointer and digital data on the panel shows the corresponding instrument information. Fig.5 can also show monitor screen of control valve, and the pointer and digital data on the panel shows real-time opening information of the control valve which is clicked. Based on the simulation models and data, we can help operators and engineers in refinery to be familiar with the flowsheet and process control system of FCCU, and also provide a visualization monitoring platform for real-time production. Simulation and visualization of the process of coal pyrolysis, the second example of virtual factory, is shown in Fig.6, which can simulate the process of how coal is decomposed to produce acetylene. Fig.6 (a), (b) show the global layout of the coal pyrolysis process, and Fig.6 (c), (d) show the specific coal particle simulation process. 5222

5 Preprints of the 18th IFAC World Congress with fault about processing units, which are based on process conditions, status of measuring points and in-out flow. Then the consequence of the given fault and the procedure of eliminating the fault will be visualized. We can take oil spilling out from tower top as an example. Because the valve of outlet was plugged, the level of material in the tower was rising. When the oil reached the top of tower, it spilled out, as illustrated in Fig.7. In order to eliminate fault, operators turned off the valve of incoming line, and turned on the valve of outlet, so the level will fall down until coming back Fig.5. Dynamic Simulation of FCCU in Virtual Factory to normal. Fig.7. Process Fault Visualization in Virtual Factory Fig.6. 3D Simulation of Coal Pyrolysis in Virtual Factory Visualization and interaction help operators get a deep Visualization and interaction make virtual factory simulation impression and make timely decision to create a safe and platform provide effective support for process simulation and stable environment in virtual factory. real-time monitoring. Dynamic-static simulation can solve many practical problems, such as setting control parameter 4.3 Process Monitoring in Virtual Factory according to different disturbances, selecting production Virtual factory integrated platform can be applied in many schemes, and analyzing or predicting variation trend of different industries, such as oil refinery and coal chemistry process plant. Without going to the real factory, users can plant. Fig.8 shows the visualization monitoring platform of wander around the process units, and operate those instruments and valves to see the response of control and real-time production information, which is useful for their decision making. Flow Measuring Instrument Temperature Measuring Instrument Control Regulating Valve Pressure Measuring Instrument Level Measuring Instrument Visualization Monitoring I Visualization Monitoring II Visualization Monitoring III Visualization Monitoring IV 4.2 Process Fault Visualization Safe and stable environment in manufacturing industry is very important. It is necessary to monitor and identify the abnormal changes in process variables both in virtual factory and real world. Process monitoring in the virtual factory helps users detect and analyze the causes of fault, and to be similar with fault that not happen in the real factory. At first, we build fault simulation models and generate process data 5223 Fig.8. Visualization of Coal Pyrolysis to Acetylene

6 coal pyrolysis to produce acetylene by using hydrogen plasma, including measuring instruments, control valve, and the pointers and digital data on the panels that visualize the varying process of real-time production. 3D visualization monitoring makes users be familiar with the production process more intuitively, which is quite different from 2D monitoring. The virtual factory has been used for operators training of coal pyrolysis process. 5. CONCLUSIONS The virtual factory integrated manufacturing system provides effective support for 3D process simulation and monitoring, with the interaction and integration among dynamic-static hybrid simulation system. Users can not only acquire all the varying production process data, but also observe the relevant 3D animations to get intuitive impression about real system operation. Therefore, the virtual factory can help them make better decisions and promote competitiveness. application in the field of logistics. Visual Computer, 24, Soares, R.P. and A.R. Secchi (2004). Modifications, simplifications and efficiency tests for the CAPE- OPEN numerical open interfaces. Computer and Chemical Engineering, 28, Sun, H.M. and W.L. Cheng (2009). The input-interface of Webcam applied in 3D virtual reality systems. Computers & Education, 53, Wu, Y.C., J.D. Zhang, Y.P. Feng and G. Rong (2006). Virtual factory laboratory system and its application. 12 th Proceedings of Information Control Problems in Manufacturing, Saint-Etienne, France, 12, ACKNOWLEDGEMENTS This work was supported by The National High Technology R&D program of China (2009AA & 2007AA40702). REFERENCES Bridge, P., R.M. Appleyard and J.W. Ward (2007). The development and evaluation of a virtual radiotherapy treatment machine using an immersive visualization environment. Computers & Education, 49, Fang, H.F., Y.P. Feng and G. Rong (2006). Simulation platform in the virtual factory laboratory system. 12 th Proceedings of Information Control Problems in Manufacturing, Saint-Etienne, France, 12, Ieronutti, L. and L. Chittaro (2007). Employing virtual humans for education and training in X3D/VRML worlds. Computers & Education, 49, Mert, B. and M. Hashemipour (2009). Virtual factory approach for implementation of holonic control in industrial applications: A case study in die-casting industry. Robotics and Computer-integrated Manufacturing, 25, Mujber, T.S., T.Szecsi and M.S.J.Hashmi (2004). Virtual reality applications in manufacturing process simulation. Journal of Materials Processing Technology, 155, Reif, R., D. Walch (2008). Augmented & Virtual Reality 5224