Solving Geometric Constraint Peoblems With Closed Garphs And IGA Algorithm

Because CAD system is important in initial modeling of products, overall design and dynamics changes, and geometric constraint solver is the kernel technology of current CAD systems, it is necessary for us to research on geometric constraint problems. In this paper we use the following method to solve large and complex problems which we will see in our lives.Firstly, we judge the type of the problem through finding the derived constraint in it. If we can find a derived constraint, then it is necessary for us to get rid of it.Secondly, we should decompose the problem base on two approaches. If the problem is planery, then we use the method based on closed graphs to do the decomposition. Or, we use the method based on decomposing under-constrained problems to do the decomposition. Get the sub-problems through this process.Thirdly, Judging the sub-problem is a unit-problem or not. If it is not, then it is necessary for us to transport it into a unit-problem.The last step we should solve the unit-problems we have get through the formly steps. In this paper we use the IGA algorithm to do this job. This approach can get the correct answer like the GA algorithm by computation, and can deal with the problems which are always met in GA algorithm, such as the chosen of the initional character.The two decomposition algorithms we used in this paper are realized by Visual C++ on VS 2005, and the IGA algorithm is also realized by us in Matlab. The experiments shows that the method we used in this paper is useful to geometric constraint problems, and it is much more efficient than the traditional methods.