Ability to refine digital prototype before constructing a real prototype for expensive proof testing is a significant benefit of virtual design tools. Overall, versatility of virtual prototype tools permits testing information to be fed back into a modified and refined digital model much more rapidly than with conventional design tests.
Virtual prototyping of assembly tasks is critical because the assembly process represents a significant part of the cost of products. Prototyping and evaluation measures are inseparable from the design process in the manufacture of a product. And made one of many physical prototypes require very expensive and time consuming, so the technology of Virtual Reality is required.
So industry can move quick/precise by combining agent behaviour and digital interface application so it as if user immersed in virtual world. Virtual Reality Teams are required for simulations that require a lot of interaction such as prototype assembly methods, or better known as the Virtual Assembly. Virtual Assembly concept has been developed as the ability to assemble a real representation of the physical model.
Virtual assembly technology is based on assessments of product model and assembly info processing, the use of interactive way, in applications of virtual real assembly , a series of issues related to assembly for verification, planning, and get the optimisation of assembly as a result, virtual reality technology is an important application in industrial production.
Product assembly technology in virtual space generates 3D model of the parts, and to operate the model, assembly experiment, test the feasibility of the assembly. Virtual assembly technology involves assembly design/plan and so on each link, is a combination of design, development, decision-making, simulation, interactive aspects of technology, in the field of product development design and manufacture.
Virtual prototyping tools have already captivated DoD interest as a viable design tool. One of the key challenges is to extend the capabilities of Virtual Reality technology beyond its current scope of design reviews. Here we present the design and implementation of a Constraint Site Visit Executive Simulation designed to support interactive assembly and disassembly tasks within virtual space.
Key techniques employed by the Constraint Site Visit Executive Simulation are direct interaction, automatic constraint recognition, constraint satisfaction and constrained motion. Several optimisation techniques have been implemented to achieve real-time interaction with large industrial models.
Constraint-based approaches for virtual assembly simulations must be combined with physics-based investigations where geometric constraints are created or deleted within the virtual environment at runtime. In addition, solutions are provided to low clearance assembly by utilising representation of complex models for accurate collision/physics results.
Constraint Site Visit Executive Simulation must also be able to validate recognized and applied constraints. The validation is the process that determines whether a constraint is still valid or is broken. A constraint is broken if the involved surfaces attempt to move apart beyond a defined threshold.
Constraint Site Visit Executive Simulation identifies new possible constraints and validates existing ones. The application specifies a list of objects to be searched for new constraints and possibly the surfaces to be tested for new constraints. If the application can determine collisions between surfaces, it can send those colliding surfaces to Constraint Site Visit Executive Simulation. This speeds up the recognition process because it cuts the number of surfaces to be tested.
Performance of the prediction model in terms of accuracy and applicability are some of the major constraints for use in real industrial applications. Accuracy of a prediction model is the degree of closeness of predicted value to the actual value. Applicability means the ability of a prediction model.
Prognostics are recognised as a key feature in maintenance strategies as it should allow avoiding maintenance spending not necessary. However, real prognostic systems are scarce in industry. That can be explained from different aspects, on of them being the difficulty of choosing an efficient technology-- many approaches to support the prognostic process exist, whose applicability is highly dependent on industrial constraints.
Constraint Site Visit Executive Simulation explores how performing failure prognostics are performed so teams can react quickly. Prognostic process must be defined and an overview of prognostic metrics is given. Following that, the prognostic approaches are described, aims at giving an overview of the prognostic area from industrial points of views.
DoD has still not proposed a formal framework to instrument the prognostic process and real prognostic systems are scarce in industry. That can be explained from different aspects. First, "prognostic" still is not a stabilised concept: there is no agreed upon way of understanding it which makes harder the definition of tools to support it in real applications. Second. many approaches for prediction exist whose applicability is highly dependent of the available knowledge on the monitored system. Third, since prognostic process is not defined there exists failure to point out the inherent challenges for DoD.
Most virtual assembly applications using constraint-based methods rely on importing pre-defined geometric constraints for assembly. Instead of freezing all degrees-of-freedom of the part as implemented by snapping methods, this approach reduces the degrees-of-freedom of parts depending on the geometric constraints among them. By reducing degrees-of freedom of parts, constraint-based methods proved useful in achieving precise part motion in virtual space not achievable when unconstrained parts are manipulated with current virtual reality input hardware.
To facilitate the development of a virtual assembly program, part interaction methods must be investigated. These part interaction methods must detect part-to-part collisions, detect hand-to part collisions and model part behavior as parts interact. DoD must investigate collision detection and part behaviour packages with specific applications to their use in immersive virtual assembly simulation and design/implement program to facilitate immersive virtual assembly methods prototyping.
Advances in virtual prototyping spaces has made possible the capability to simulating visual fidelity to a very high level. The next big challenge for virtual prototyping teams is simulating realistic interaction. Virtual prototyping, sometimes referred to as digital prototyping, is widely adopted by industry to simulate visual appearance and functionalities of production. But conventional virtual prototyping techniques lack the simulation of the physical properties of a real interaction between user and product. Force feedback is based of development of virtual prototyping.
The success of DoD enterprise efforts not only requires short product inception but also makes necessary the integration of engineering, marketing and production components so it is important that manufacturing plan/assess methods work within the framework of the product design cycle. To improve the value added to a product, technology development is critical and tools such as virtual reality and rapid prototyping can provide combined advantages to DoD enterprises.
Quality requirements in rapid prototyping requires iterative process and building prototypes can be costly, often based upon trial-and-error. Modern markets require shorter time scales for product design. Concurrent Engineering concepts encourage addressing issues such as maintenance very early in the design process but lack of simulation tools is a big challenge.
Simulation of maintenance operations allows maintenance to be addressed in early design stages. This reduces unforeseen problems creeping into the design as it progresses through its life cycle, consequently saving both time and money while improving product quality.
Our Virtual Prototyping Team has been investigating the applicability of virtual reality to interactive maintenance simulation. A system that can simulate realistic maintenance operations interactively is demanded by the industry. Must use virtual constructs to assess maintenance operations before any physical prototype is available.
Besides speeding up the development process, the assessment of virtual models can also reduce the number of required physical prototypes. Such a tool has the potential to reduce the time-to-market and the development cost.
Input module consists of three parts: digital prototype, maintenance, and support. A digital prototype sub module and maintenance sub module are used to build maintenance simulation. The digital prototype sub module contains the rigid product containing cable and cable routing. In the maintenance sub module, the maintainers, maintenance tools, maintenance task, maintenance procedure, and maintenance path need to be determined.
The support sub module provides for future investigations such as maintainability evaluation, procedure, support tools and equipment assessments and maintenance time prediction. The maintenance sub module main includes knowledge/resource base.
Service and maintenance is an intricate specialist task and machine builders often have to provide service at short notice. Machine builders would very much benefit from extended possibilities to monitor and diagnose equipment operating at distant locations – both for condition-based preventive maintenance and for diagnostic purposes before bringing in qualified maintenance personnel and spare parts.
Simulation models as used in virtual engineering during development of manufacturing systems can be used during the operation phase of manufacturing systems as well. In order to fully benefit from this, the simulation model must be connected to the physical system and other business operations In this way, information regarding past operation and current status can be fused with information regarding possible future operation, explored through virtual scenarios.
The overall result can be used for decision support in for instance operational planning or service and maintenance. In this way, simulation serves as a tool for arriving at a situation in which the future scenarios are perhaps not completely known, but in which one can readily address the most likely scenarios in an adequate manner.
Artificial intelligence can play a role in virtual manufacturing by improving simulation models or by offering better decision support. Extending the use of simulation models from the design phase to the operation phase also has advantages when new products are to be introduced or the manufacturing system needs to be reconfigured.
Virtual Reality is an attractive option since it offers the user a sense of being immersed in information where objects have a sense of ‘presence’ and allows them to interface with information at full scale if required. A design begins with an image or idea and the concept is disseminated via diagrams and descriptive speech.
Typically, information sources for conducting various virtual reality activities are not one single specific source, but instead all the different technological and business information systems that are used in DoD The integration of these sources is not usually out-of-the-box-solution but most often highly customised solutions, engineered by specialists.
Information valuable in virtual reality manufacturing has the same problem as any other piece of information; it is often bound to the structure used by business system it was created in. The lack of possibility to use a common format for all information, not depending on any application tool, poses problems.
There are three typical scenarios: 1) The information exists and it can be used directly or converted to a format that can be used, 2) The information exists but it cannot be translated into a format that can be read by the virtual design tool so information has to be recreated in a new format, 3) The information is not available and has to be created or collected. The lesson learned here is that if the information exists, it makes sense to have it presented in a format that is more or less neutral.
During the early stages of design, designers may employ a range of tools and techniques while involved in key activities such as generating, selecting, and evaluating design concepts. These tools may include sketching, building prototypes, other types of modeling, or verbal or written text about a design idea.
In particular, the process of constructing physical prototypes of a design idea can uncover important design issues not be apparent from a 2D representation such as a sketch. Also, the hands-on experience of manipulating materials for a prototype, including fabrication of components and assembly, provides the designer with an opportunity to interact with a design, particularly to explore the space of design concepts, generate new designs or start to pare down the design space.
A key experimental field of application for virtual prototyping can be separated into two categories: 1) user point of view and ability to use a product, and 2) concerns user point of view and capacity to perform, without additional risks, the assembly of the product as well as the tasks associated to his workstation. User point of view with a focus on the importance of behaviour input observations to the design process.
Virtual Reality can facilitate the involvement of external stakeholders in product design. Stakeholder involvement can improve the information quality and quantity; end-user feedback for instance facilitates concept generation and selection, or identifies usability issues in an early stage. But with only limited design information available it is difficult to provide stakeholders with a clear presentation of a product concept and future use context so virtual reality tech must to create realistic concept representations in the early stages of the design process.
Virtual Reality tech creates an alternative reality in which worlds, objects and characters can be experienced that may not yet be available in reality so stakeholders are allowed to not only see the future product- achieved with concept sketch or mockup, but also experience the product and the interactions with its use context.
Rapid Prototyping technologies are increasingly being applied to produce functional prototypes and the direct manufacturing of small components. Despite its flexibility, these systems have common drawbacks such as slow build rates, a limited number of build axes and the need for post processing.
Behaviour activities in assembly tasks are evaluated based on the adoption of immersive virtual reality along with a novel non-layered rapid prototyping for manufacturing of components to facilitate a better understanding of design for manufacture and assembly by utilising equivalent scale digital and physical prototyping in one rapid prototyping system.
Rapid prototyping is a manufacturing process where preproduction models are built to test various aspects of design functionality utilising an additive process in which parts are built by adding material layer upon layer as opposed to traditional techniques such as machining which is subtractive i.e. removing material.
Depending on the industry, it is almost certain that pre-production prototypes are required, either as virtual or physical types These prototypes can be near net shapes. Cost is always a factor and while physical prototype may ultimately be needed, its virtual counterpart is studied to improve product design, quality and performance, assembly and other issues. This reduces manufacturing risks of prototypes early in the product development cycle, and consequently reduces the number of costly design-build-test cycles.
Rapid Prototyping produces a physical prototype from digital model by building a part layer by layer in shorter time than more traditional prototyping methods. Unlike the traditional material removal processes, most rapid prototyping processes have to build a physical model by gradually adding or solidifying materials layer by layer.
A significant amount of development time and costs are often spent on product design and process validation. For this purpose, prototypes are commonly used for verification and testing of processes, and functionalities. Fabrication of a prototype is an expensive and time-consuming undertaking.
Prototypes can be hard or soft. A hard prototype is a model which can be physically touched and manipulated, while a soft one is digitally simulated and may be regarded as a computer graphical image of the product.
A hard prototype is traditionally crafted by a skilled pattern-maker. It is slow and dimensionally inconsistent. Rapid prototyping machine is faster process that fabricates a physical prototype additively from a 3D model layer by layer and systems are now widely used in product development.
Virtual prototyping is a process of using a digital prototype, in lieu of a physical one, for testing and evaluation of specific characteristics of a product or a manufacturing process. Virtual prototypes can be sent to customers to solicit comments, or the process parameters can be tuned for optimal fabrication of physical ones. So virtual prototyping reduces the number of physical iterations and thereby the associated manufacturing overheads, leading to faster and cost-effective product development.
While production of single-material prototypes is the norm, there is an increasing need for multi-material prototypes. It would be useful to develop multi-material layered manufacturing technology. Control of the material-depositing mechanism would require advanced application system to accomplish effective and efficient fabrication of multi-material prototypes.
Manufacturers use new tech to produce prototypes of products for design evaluation, and as master patterns for production tools. There is an increasing demand for multi-material prototypes because high value-added products tend to involve advanced and complex design. Multi-material prototype able to clearly differentiate one part from another of a product will be particularly useful for designers.
In order to simulate physical mockups in an effort to provide a reliable evaluation space for assembly tech, virtual assembly systems must be able to accurately simulate real world interactions with virtual parts, along with their physical behaviour and properties.
To replace or reduce the current prototyping practices, a virtual assembly simulation must be capable of addressing both the geometric and the subjective evaluations required in a virtual assembly operation.
If successful, this capability could provide the basis for many useful virtual space that address various aspects of the product life cycle such as workstation layout, tooling design, off-line training, maintenance, and prototyping service.
Complex interactions involved while performing a simple assembly task such as inserting a pin into a hole have been presented here. Challenges involved in simulating such complex interactions are identified. Detailed examples in the Field illustrate the benefits of using either collision detection, constraint-based modeling or physics-based modeling as the only interaction method is not sufficient.
Techniques described here will probably not be entirely capable of simulating all aspects of the complex assembly process. We conclude combinations of different methods and techniques will required to realistically simulate complex interactions and facilitate assembly of complex parts in Virtual Reality Space.
1. Enables reduced time to market
2. Allows for early product testing
3. Can conduct expensive or impossible tests
4. Reduces the need for physical prototype
5. Provides common design standard and language
6. Protects profit margin. and increases agility
7. Drives down progamme development costs
8. Reduces scope/scale of engineering changes
9. Provides solutions to design complexity
10. Promotes group sharing of digital mock-ups