Crawler cranes are the most expensive and frequently shared resource on construction sites, industries, etc. It is engaged in offering various combination for booms and large-capacity of mobile cranes to meet the building industry requirements. Computer simulation has proved to be an effective tool for aiding practitioners in modeling complex construction operations, especially three-dimensional simulation that can provide interactive, three-dimensional graphics. As a graphic standard, OpenGL has powerful three-dimensional graphic processing abilities, but is weakness in three-dimensional modeling. Bounding Hierarchical Volumes Tree (BHVT) is very popular structures for objects storage of virtual scenes. Based on BHVT, a method of three-dimensional modeling is proposed. According to its structure and characteristics, the model of the crawler crane is designed. To achieve three-dimensional simulation for a main hoisting crane and an assistant crane (i.e., sliding tail crane) cooperative lifting, several typical mathematical models are established. When simulating the lifting process in the cooperative working mode, the changes of cranes and the lifting equipment, needed for steady lifting, are figured out simultaneously, and then those changes are output to form the relevant curves. The curves are analyzed to decide whether the lifting plan that using a main hoisting crane and a sliding tail crane to lift is safe and reasonable. For the sake of a better interactive simulation, object-oriented framework for three-dimensional graphic creation based on OpenGL is developed, it consists of class BHVTNode, class camera and class renderer, which make data and instructions separated. Combining the class camera and class renderer with the technology BHVT, succeed to simulate the lifting operations of crawler crane, especially achieve the animation of the cooperative lifting, it is visual to observe the whole lifting process, which is good for assisting to design the lifting plan.
Interactive simulation modeling of automated storage retrieval systems
