Collision Detection for Virtual Prototyping Environments

Today's development of industrial products faces high requirements. Manufacturing companies need to produce high quality products, of low cost, to be marketed earlier than those of the competitors. Products must satisfy consumer requirements, must be developed fast, and must be of high quality. Many manufactures are adopting concurrent engineering in an attempt to reduce the lead time for new products and improve their quality while reducing manufacturing costs. The integration of expertise from design, engineering, testing, manufacturing and maintenance in a unified concurrent engineering framework has led to effective rapid prototyping. The ultimate development of rapid prototyping is virtual prototyping. In a virtual prototyping environment, a 3D virtual model of the product is used in the different stages of the product life cycle. The three-dimensional virtual model behaves as a physical prototype enabling the simulation of all aspects of a product, such as, mechanical design, kinematics, dynamics, testing and maintenance, in a unified framework. In this way, there is no need to build a physical prototype, which is difficult to modify, reducing furthermore the costs and the time to market the product. The Virtual Prototyping Group at the Centre for Virtual Environments at the University of Salford has been exploring the applicability of virtual reality in different product development stages such as maintenance simulation, which involves complex object interaction and control [Fernando et al., 2001]. Work is being carried on in the development of a simulation environment that allows designers and engineers to assess maintenance tasks before any physical prototype is built. In a maintenance simulation scenario, it is necessary to allow the user to interactively carry out assembly and disassembly operations on the virtual prototypes in a realistic way. In such environment, the three-dimensional virtual prototypes need to simulate physical properties realistic and interactively. In the simulation of assembly and disassembly operations, finding precise collisions is an important task for achieving realistic behaviour [Munlin, 1995]. When assembling two components, it is necessary to find which parts are colliding, to determine possible constraints and simulate solidity. When simulating the dynamic behaviour of a virtual prototype, collision detection is used again to determine the exact interactions between different components. If a user wants to grab a virtual prototype, a collision check must be done to guarantee that he is touching it.