A Virtual Training System For Quay Crane Operators

At present, the quay cranes are major port loading and unloading equipments. With the rapid development of container shipping, a lot of quay crane operators are urgently needed. However, training operators of quay cranes in ship ports is an important and long duration activity. The real quay cranes are usually needed for actual work and from a safety point of view they are not convenient for trainees to practice operations as well. Therefore, to remedy this problem, a virtual training system for quay crane operators based on the desktop virtual reality technique was developed.Six questions have been focused on in this paper, which are how to design the system structure, determine the system development process, create three-dimensional models, drive model movement, realize collision detection and response, analyze the system performance. The research contents are as follows:(1) We analyzed traveling mechanism, loading and unloading process of real quay container cranes, thereby clearing the system function requirements. Next, the system overall structure was designed based on the function requirements. By analyzing the advantages and disadvantages of the current main modeling software, we determined to use Creator for creating3D models, Vega for model execution.(2) In order to better create system three-dimensional models, this paper first introduced the common modeling skills of the Creator software, DOF technique and model optimization technique. According to analyze the basic structure, geometric parameters and structural characteristics of real quay cranes, the crane modeling parameters was determined. Therefore, the crane geometric model was created by its defined parameters. At the same time, to make the virtual quay crane have the ability of activity, the paper discussed the method of creating the crane DOF nodes as well. In addition, the paper also respectively analyzed the modeling parameters for the spreader and environment models, so as to create the three-dimensional models of the spreader and the environment. Finally, the three-dimensional modeling of the system was finished.(3) In order to better understand the Vega software drive principle of the model, The paper introduced Vega driving technique including model execution principle and execution process of application programs. The methods of controlling crane DOF nodes moving, rope elongation and shortening to realize its three mechanism movements were studied. The method of driving the crane DOF nodes movement to realize the crane cart and trolley walking were studied. And the realization of the spreader raising and lowering motion through controlling the ropes extension or contraction was also studied. In addition, the paper also analyzed the methods of setting the system multiple viewpoints, grabbing and placing the container. How to realize container truck movement, virtual people movement, and the surface wave were discussed as well. To enhance the verisimilitude of the simulation training environments, this paper further studied the dynamic model of the quay crane and the load swing model. Finally, we programmed based on the load swing model to realize the virtual quay crane load swinging.(4) Collision detection is a key technique in developing the virtual training system. This paper analyzed the principle of collision detection and eight kinds of collision detection methods of Vega software. Combining with the spreader collision characteristics in the virtual scene, the collision detection methods of containers and the spreader were determined. At last, how to realize the collision response after the spreader colliding with the containers was discussed in detail.Finally, the system was tested by repeatedly practicing quay crane operations. And the test results show that the virtual training system provides a realistic simulation training environment and a real operation sense.