Simulation and Visualization Using a Remote Database

Michael Iuliano

Manufacturing Systems Integration Division

National Institute of Standards and Technology

Introduction

The National Advanced Manufacturing Testbed (NAMT) program was conducted at the

National Institute of Standards and Technology (NIST) from 1996 to 2000. The NAMT

was initiated by the Manufacturing Engineering Laboratory (MEL) to enable and

accelerate the development of standards related to the interoperability of manufacturing

systems and to aid in the injection of new technologies into next-generation

manufacturing systems. The NAMT also served as a research testbed for development

and analysis of computer-based manufacturing technology. The NAMT was conceived

and deployed with the participation of both industry and government and provided a

cross disciplinary research environment.

The NAMT consisted of equipment, personnel, collaborators, and projects that utilize

resources within the testbed. The infrastructure put in place by NAMT allowed

geographically distributed project participants to use new virtual enterprise technology to

conduct research projects. The NAMT infrastructure consisted of : [NAMT99]

‘Physical communications components, such as networking gateways, routers, and

networking software, that provide collaborators with access to equipment, documents,

databases, project information, test data, and testing suites. Commercial and experimental

software applications, such as design, engineering, and simulation packages, are remotely

accessible, and will provide capabilities that include teleoperating physical devices.

Multimedia communications, such as videoconferencing, groupware, and e-mail

exploders, to facilitate effective collaboration among remotely located partners, as well as

security and safety mechanisms. Advanced machine tools and research equipment that

might otherwise be unavailable to collaborators. Vast and varied technical expertise that

is immediately accessible through the national network. ‘ See figure 1.

Figure 1: NAMT Infrastructure.

NIST ATM network

Molecular Beam Epitaxy Lab

Machine Tool Lab

NAMT Lab

Inspection Lab

Scanning Electron

Microscopes Lab

Sheet Metal

Testing Lab

Scanning Probed

Microscope Lab

Radiation

Calibration Lab

Construction

Site Labs

Public ATM networks

Government

Agencies

Academia

Industry

WWW

Internet Connection

HEXAPOD

NISTIR 6717
NAMT was implemented to also act as a collabortory. More and more enterprises are

moving toward these types of environments. The NAMT was designed with adaptability

in mind to allow research projects to move together in time with changing technologies.

The Virtual Cybernetic Building Testbed (VCBT) project was one of the NAMT

projects. This paper describes work done in this project.

Virtual Cybernetic Building Testbed (VCBT) Project Introduction

Building control systems are evolving to the point where they need to be more tightly

integrated with each other. Building control system research can not be properly

conducted in real buildings because real buildings can not be used to create conditions

interesting to a researcher, i.e. a fire. This creates a need for an environment where

simulations of building control systems can be developed, integrated, and tested together.

The Building and Fire Research Laboratory (BFRL) at NIST has been conducting

research in this area for many years. This research has led to various projects consisting

of hybrid systems of hardware and software. Thus the VCBT project is aimed at

providing a state-of-the-art environment where simulations, computer systems, building

control hardware, and data can all be studied in a virtual testbed. This testbed could be

used by control manufacturers, service providers, and software engineers to develop and

evaluate control strategies, develop algorithms, and control products that use the BACnet

[BACNET97] protocol. The existence and use of the VCBT by newly developing

building service companies will greatly accelerate the emergence of new and better

building services such as fault detection and diagnosis, automated commissioning,

building system optimization, and predictive maintenance.

The VCBT consists of separate Heating, Venting and Air Conditioning (HVAC);

building, and fire emulators located in different NIST buildings working together with a

center coordinating object and a data logger. The HVAC and fire emulators are

implemented as simulation models. The building emulator is implemented as a Virtual

Reality Modeling Language (VRML) [VRML 96] model of a building that runs inside a

World Wide Web (WWW) browser. A VRML interface to java allows a VRML model to

be updated via a java applet running in the same WWW browser. It is this applet that

provides the connection to the other emulators in the VCBT using the java, CORBA,

database and JDBC technologies.

This paper is aimed at describing the implementation of the VRML building

emulator/user interface. The building is being modeled based on a real building on the

campus of the Massachusetts Institute of Technology (MIT).

VRML Building Model

The VRML building model can be updated using a VRML application programmer’s

interface (API) called External Authoring Interface (EAI) to translate, scale and color

geometries in the VRML building model. This basic approach is used to visualize the
results of the simulations from the other emulators in real time. The details of the

implementation of this approach are described below.

The VRML building model contains basic VRML geometry: polygons, cylinders, boxes,

coordinates. These geomtetries can be combined into what VRML calls a node. These

nodes can have names. It is by this name that an external java applet uses these names to

refer to a node in a VRML model via the EAI interface. The VRML building model is a

custom-built VRML model with nodes that have names like: vent1, vent2, vav3, ahu1,

supplyfan, and so on. The VRML building model consists of three basic components: (1)

the building with all rooms dimensioned according to the Massachusetts Institute of

Technology (MIT) floor plan, (2) a three-room detailed model where a simulated fire

takes place with flames, smoke, temperature gauge and touch sensors on key objects like

the air handling unit (AHU), and 3) an image of the floor plan for one of the floors of the

MIT building mainly used to provide context.

Item 1 above was generated by a C application developed in the early stages of the

project . The application automatically generates VRML models of buildings from data

stored in a database. An information model was developed to support this purpose (See

figure 2). In figure 2, the lines indicate a relationship and the relationship is marked with

a "1" or "m" indicating a one-to-many or one-to-one relation between model entities. This

information model was implemented in a schema in a relational database. The application

was then developed to interact with this schema. The colors of the rooms are based on the

current temperature of the rooms, i.e., red is hot, blue is cold, purple is very cold. We

took the floor plans of three floors of the MIT building (See figure 3 for the second floor

plan) and used a ruler to estimate the dimensions of the rooms. We then entered this data

into the database and generated temperatures for the rooms. The application then

generated the model of the MIT building. If we wanted to re-dimension or change the

color of any of the rooms, we could simple change a value in the database and regenerate

the model.

Figure 2: Relational VRML building information model.

The scenario around which the VRML building model was developed involves a fire that

starts in a room in the building. The fire starts on two pieces of paper located on a chair.

The fire has flames and causes smoke and other contaminants like carbon dioxide, carbon

1

m

 1

m

1

m

 1 m 1 m

 1

 1

m

 1 m m

Room

Building

Zone

Wall

Room Status

AHU AHU Supply Fan

AHU Return Fan

VAVBox
monoxide, and nitrogen. The idea is to see the effects of the fire and monitor how the

Heating, Venting and Air conditioning (HVAC) systems handle and respond to the

situation. The relevant data includes: the simulation time, the upper smoke layer

temperature in the room where the fire starts, the lower oxygen layer temperature in the

room where the fire starts, the concentrations of smoke and carbon monoxide in the room

where the fire starts, the air handling unit’s (AHU) supply and return fan’s rotational

speeds and mass flow rates, the variable air volume (VAV) unit’s air mass flow rate and

inlet/outlet pressures for all three rooms. These were the major items of interest in the

development of the VCBT building model. The VCBT building model was built so that

different nodes for each additional type of contaminant can be added in later, for

example, the blue arrows. The arrows can be updated by changing their color and size or

pulse to indicate conditions in the air ducts. The arrows also have names. The simplified

system diagram of the VCBT emulators is shown in figure 4.

Figure 3: Second floor plan of MIT building being represented in the VCBT building

VRML model.
Figure 4 Simplified VCBT system diagram.

Figure 5: System diagram for VRML building emulator.

A detailed system diagram of the VRML building emulator is shown in figure 5. The

main visualization component consists of a VRML building model that is controlled by a

Workstation

PC

Java Application - CORBA

HTML page in WWW browser

Center

CORBA

CORBA

CFAST (Fire)

CORBA

HVACSIM+ (HVAC)

CORBA

VRML GUI (Building)

VRML Building Model

External Authoring Interface

Java Applet

UNIX workstation

Database

WWW Server

Java application

Java Class Socket_int

Java Class Oracle_int

CENTER

Fire

emulator

HVAC

emulator

socket

socket

JDBC

JDBC

Serve

Web

page

Data

Logger

 CORBA

UNIX shell script

C++ Program

CORBA

CORBA

Data Logger

(HVAC)
java applet via VRML's EAI interface. This java applet receives data to update the

VRML building model via a communications socket connection with a java application

that runs on a UNIX workstation. This java application can gets its data in one of two

ways. It can use JDBC calls to access simulation data in a relational database. The data is

populated into the database via JDBC from a java/CORBA application that

communicates and receives data from the other VCBT emulators using CORBA as the

emulators execute their simulations. The data path allows the simulation data to be

recorded in the database for later playback. Second, it can open a socket connection with

the java/CORBA application. This data path bypasses the recording of the simulation

data in the database. See figures 6 through 10 for a representation of the simulation in the

VRML building model.

Conclusion

The NAMT was initiated by the Manufacturing Engineering Laboratory (MEL) to enable

and accelerate the development of standards related to the interoperability of

manufacturing systems and to aid in the ejection of new technologies into next generation

manufacturing systems. The Virtual Cybernetic Building Testbed (VCBT) project was

initiated to allow researchers to integrate building control systems seamlessly under

simulated controlled conditions. The VCBT consists of several building control system

emulators that are implemented as simulations. When the emulators are executed

together, the results of the simulation can be visualized using the VRML building

emulator.

References:

[NAMT99], WWW pages for NAMT, "www.nist.gov/mel/".

[VRML96], Hartman, J., Wernecke, J., "The VRML 2.0 Handbook", Addison-Wesly

publishing 1996.

[BACNET97], Bushby, S. T. ," BACnet(trademark): A Standard Communication

Infrastructure for Intelligent Buildings.", Automation in Construction, pages 529-540,

1997.

DISCLAIMER

Commercial equipment and materials are identified in order to adequately specify certain

procedures. In no case does such identification imply recommendation or endorsement by

the National Institute of Standards and Technology, nor does it imply that the materials or

equipment identified are necessarily the best available for the purpose.
Figure 6: Three floors of MIT building with color coded rooms according to room

temperature.
Figure 7: Three rooms of MIT building where simulated fire takes place.

Figure 8: Fire starting on chair.
Figure 9: Side view of room where fire starts with temperature display and smoke cloud.

Figure 10: Side view of room with smoke and fire progressing.