Computer simulation is recognised by the defence community around the world as one of the key technologies for the 1990s. Of course there is nothing new about the use of simula-tion and simulators in the military. What is new, however, are the kinds of technology involved and the types of mission for which simulations and simulators are being used.
Several factors contribute to the important role played by computer simulation for military applications. First, although defence budgets have shrunk considerably over the past few years, the diversity and complexity of missions that armed forces have to prepare for and exe-cute has increased. This has led the defence establishment to look for economical ways to train military personnel and find alternatives to validate new military doctrines before commit-ting to large-scale live exercises or missions. Secondly, the rapid developments in computer hardware and software have enabled simulation to evolve from a research technology to an operational tool. Increases in the speed of computers and associated graphics processors, development of real-time image generators and simulation frameworks that take advantage of this new hardware, and unifying communica-tion protocols such as DIS have contributed to making computer simulation an integral part of technologies required to guarantee the level of effectiveness of modern armed forces.
However, budgets for simulation and training systems have not been spared by cuts. Also, lead times to develop, maintain and upgrade simulation and training systems are often too long and the costs of these systems too high in the current budget context. Consequently, new ways must be found to specify, build and deploy simulation and training applications that must leverage current technological advances at an affordable cost.
Until recently the development of simulation and training systems followed the traditional model applied to other military equipments. This model is characterised by a relatively long requirements specification process, followed by an equally long bidding and award process. The time and costs associated with developing prototypes often have precluded end-users from being involved in the refinement of sys-tems specification early enough in the cycle.
Prime and sub-contractors engaged in the development of these devices often relied on customised technologies developed in-house for other, often non-related, projects. The over-head associated with customising and main-taining these technologies was reflected in the cost of the new system. This model has two drawbacks. First, it is unlikely to lead to the fast absorption curve of new technologies that is required to keep simulation and training sys-tems in phase with current and future techno-logical advances. Secondly, this model does not result in any cost saving to the end-user.
Building modern simulation and training sys-tems involves two tasks. One must assemble and integrate into a coherent framework all the basic components and technologies required for the system to work. Also, domain expertise, closely linked to specific application needs, must be applied to the generic system so it meets users' requirements. The availability of commercial-off-the-shelf (COTS) software tools allows systems to be rapidly prototyped and built. In turn, it allows the systems inte-grator to concentrate its resources on the user's application rather than on customising and maintaining ageing technologies. This results in the development and maintenance of modern systems at a lower cost.
For many years Virtual Prototypes, Inc (VPI) has developed software products to support the new concept of distributed simulation. The centrepiece of its simulation environment is STAGE (scenario toolkit and generation environment) that is a flexible, commercial off-the-shelf tactical scenario generation and execution framework. STAGE allows users to prototype and develop a distributed simulation system connecting real or simulated equipment and subsystems through a network to a tactical database and simulation models. Tactical scenarios consisting of target motion, interaction and detection mechanisms can be defined easily using an intuitive graphical user interface (GUI). In addition, user-specified high fidelity simula-tion models can be integrated in STAGE.
STAGE has three main components: the data-base editor (DE and SAD); the simulation engine (SIM); and the development kit (DI).
| The three main components of STAGE include the database editor (DE and SAD), the simulation engine (SIM) and the development kit (DI) |
During the preparation phase, the DE is used to build and generate the components of a scenario. The scenario then is run in real-time by the SIM to produce an evolving synthetic environment. The entities that comprise the scenario are stored in a tactical database. During the run-time phase, the DE is used to visualise the evolution and status of the scenario's entities within the synthetic environment. During the preparation and run-time phases, the focal point of the DE's user interface is the situation awareness display (SAD) that provides an overall view of the scenario. The SAD consists of a map of the gaming area overlaid with symbology representing the scenario and its entities.
The simulation engine is responsible for bringing to life the synthetic environment by running a scenario. It communicates with the DE to obtain the description of the scenarios and its enti-ties, to export data about the evolution of the scenario and to respond to simulation flow control commands. The SIM makes available key descriptive and run-time state information about the scenario and its entities to external simulation processes with shared area. The SIM appears as the central simulation in a set of co-operating simulation processes.
The development kit (DK) allows users to extend the capabilities of the simulation in terms of entities and the associated models and behav-iours. The DK consists of a set of libraries and the development interface (DI). The libraries are used to add functionality and user-built models to the SIM. The DI is a powerful graphi-cal data structure editor. With the DI users are able to create and modify the profiles the DE will manipulate.
The breadth and capabilities of COTS software tools is increasing constantly, making it easier for developers to prototype their applications quickly and build them effectively and more efficiently. The growing demand for these types of product and the healthy competitive climate that will generate as a result will lead to technological advances that can only benefit the military simulation and training community while at the same time reducing the development and deploy-ment costs of the systems they need.
