Simulation, as used here, is a method for representing or approximating an object, event, or environment. In this context, simulation can include physical mockups, computer models, or mathematical models. Virtual reality, or VR, is a new technology that has been defined as the total or near total immersion of an observer in a three-dimensional, synthetic environment in which the observer interacts with the environment.
Simulation. Simulation is frequently used to evaluate the maintainability characteristics of a design. Mockups can be built to represent a finished product so that access for performing maintenance, for example, can be evaluated.
Virtual Reality. VR is a method of simulating an environment that:
- is too dangerous for an observer
- lacks elements, such as an aircraft or other item of study
- does not exist
- is not accessible
Three different types of VR have been developed. Although not all these types exactly fit the definition of virtual reality, they do represent variations of the same basic technology.
The three types of VR are:
- Telepresence in which observers perceive and interact with a distant environment
- Augmented reality, a combination of a real and synthetic environment, in which a real environment is annotated or augmented with additional details or elements
- Virtual reality in which a synthetic environment is created for the observer
Telepresence is used when the environment is dangerous or inaccessible. An example of the former case is disarming a bomb, a hazardous task for a person, even if wearing a helmet, body armor, and other safety devices. A robot equipped with telepresence can be operated by an operator located a safe distance from the bomb with almost the same feeling of "being there" as if he or she were actually at the site of the bomb. An example of the latter case is controlling robots in earth orbit from a ground station on earth.
In augmented reality, information and details are "added" to the real world, providing guidance, instructions, and so forth to help an observer's understanding or performance. Three examples follow. First, in an augmented reality approach to video conferencing, a three-dimensional image of a new product still in design could be generated from computer-aided design (CAD) files and "placed" on the desk or table in front of each conferee. The nomenclature of parts could be "superimposed" on them and would "follow" them no matter how they were moved within the range of the video camera. Another example of the use of augmented reality is the superimposing of the proper locations for drilling holes in an aircraft skin with other information, such as proper hole size. Finally, surfaces or features of an item that are physically occluded can be displayed as an overlay so that an observer can "see" them without disassembling the item.
In a total virtual reality environment, nothing (or very little) but the user is "real." Objects and their physical characteristics, the physical environment, the time of day, and so forth are all generated by a computer and displayed to the user, usually through goggles or a helmet. The user "sees" and can interact with objects in the environment.
Applications for Maintainability . VR has definite applications for designing maintainable equipment. For example, based on computer-aided design data files, a virtual copy of the product can be "produced." The maintainability engineer can then enter a virtual environment (VE) in which maintenance can be "performed" on the product. The accessibility of components, whether an item fits in an allocated space, and the approximate
time required to perform specific maintenance actions all can be evaluated using VR. Virtual copies of support equipment, such as dollies and lifting devices, can be evaluated by "performing" maintenance activities with them. VR maintenance aids could allow technicians to view virtual information panels "superimposed" (using augmented reality techniques) on the actual equipment. In general, virtual reality can be used by the maintainability engineer to analyze:
- reachability and access
- field of view
- lifting guidelines
- energy expenditure
- activity timing
In addition to designing for maintainability, VR has many potential training applications. Maintenance and manufacturing procedures, especially procedures that are seldom performed or are difficult to teach using conventional approaches, can be taught using VR. VR could also be used to train individuals in performing hazardous procedures, disposing of hazardous materials, or performing life-threatening procedures. For example, surgeons can now "perform" operations without actually using any physical tools or a live patient.
As has been the case with previous new technologies, the possible uses of VR cannot be fully appreciated or anticipated. As VR matures, the applications related to design for maintainability will certainly increase in number and in fidelity.