Ant Colony Optimization Using Variant Pheromones for Pipe Routing

When routing pipes in a building, mutually hazardous pipes must be separated by safety gaps to prevent dangers while friendly pipes should be bundled to save construction and maintenance costs. These two goals are in conflict with each other. It is impossible to accomplish them simultaneously by using conventional ant colony optimization (ACO) piping methods, which focus on finding shorter and less-bended pipe paths. This article presents an innovative ACO piping method to resolve this problem. First, the proposed method divides the ants into groups. Each ant group is responsible for routing a single type of pipes. The pheromones, secreted by an ant group, are attractive, neutral, or repelling to other ant groups. Secondly, besides releasing pheromones in their trails when searching pipe paths, the ants also deposit pheromones in the pipes, which had been created by them. Thirdly, these pheromones remain in the finished pipes and diffuse to the surrounding areas to attract friendly ants and to drive away mutually hazardous ants in the following routing computations. As a result, pipes arranged by friendly ant groups tend to cluster while pipes routed by mutually hazardous ant groups are separated by safety gaps.