Towards Automated Welding in Big Shipbuilding Assisted by Programed Robotic Arm Using a Measuring Arm
This paper presents an automated robotic welding system adapted for shipbuilding in large shipyards. This solution has been devised in the shipyard of Navantia located in the south of Spain, in the context of ROBOT FASE II R&D project. It also presents the human teams that have developed this welding system. The article explains the 3 parts that make up the welding system. The location of the robotic welding arm of the Fanuc brand is detailed in the first part. In addition, the gantry and spatial coordinate axes are described and indicated where the robotic arm is housed. The second part contains the system capture of the coordinates in the space for the reading of the singular points to be soldered. These points are measured by a portable measuring arm. The last part is composed of the system of communication between the different parts throughout the computer. The computer is responsible for synchronizing the measuring arm and the robotic welding arm by translating the points to be soldered.
Automatic welding robot system for the horizontal position in the shipyard
In the horizontal position welding, a series of trials for automatic welding technique have been carried out. However, their results have been used under some limited scopes. In this study, a welding robot system was developed to automate the horizontal welding in ship building construction. The small mechanical robot incorporates CAN-communication based motor drivers to minimize wiring of the welding robot. In order to weld on various gaps between workpieces, an automatic gap measurement and an algorithm for weld pass design were developed. A database of optimum welding conditions for FCAW(flux cored arc welding) and GMAW(gas metal arc welding) process was also established. The developed welding robot system showed a good performance in the shop test, and it is being optimized in HHI shipyard.
Using Fuzzy-Delphi technique to determine the concession period in BOT projects
BOT projects are affected by several risks and uncertainties. One of the most important issues in this type of contract is to determine the length of concession period considering these uncertainties. The previous studies have developed several models to determine the concession period. However, the uncertainties are not taking into account in most of the previous works. Moreover, none of the previous researches has the capability to aggregate the opinions of different experts being involved in a project regarding the values of the uncertain input parameters. In this research, a Fuzzy-Delphi technique is implemented to determine the length of concession period considering uncertainties. Using the proposed Fuzzy-Delphi technique, the values of different uncertain factors affecting a BOT project is determined considering opinions of a group of experts. The NPV value is calculated considering the resulted aggregated values of uncertain input parameters. Finally, the concession period is determined using fuzzy approach. A case study is conducted to evaluate the performance of the proposed methodology. It is shown that the concession period is determined more effectively using the proposed approach.