트랜스포터 SPMT 안정성에 관한 연구

Abstract

Abstract

Today, there is a global trend of rapid increase in the amount of logistic transportation. According to this trend, ships are also becoming larger. Shipbuilding companies attempted to increase their market share concentrating more on security of large ships.

With enlarging ship order market and increasing size of ships being ordered, shipbuilding companies placed efforts on finding effective building method. As a result, they successfully developed a shipbuilding technology in which large scale ships with thousands of ton are built in a short period by making large blocks and performing final assembly on a dock or land. With development of such construction method, turnover rate of limited docks and assembly spaces was increased, while securing an environment for simultaneous building.

Heavy lift transporting device called transporter is at the center of such method. Transportation by the transporter is required for unit block transport and final assembly. In addition, among manufacturing methods used in building of all ships, the role of transporter in final assembly of large blocks was changed absolutely. Its role extends to include transport of marine structure building blocks, transport of shipbuilding apparatus (ship engines, cranes and etc.) and transport of large materials in shipyards. In case of marine structures and shipbuilding apparatus, lifting location and method for transporter often differ from normal shipbuilding blocks. There also are many difficulties for drivers to make the decision on stability during works. Although the role of transporter in shipbuilding has become absolute, there is relatively little consideration on security of work stability with the use of transporter used throughout shipbuilding industry in comparison to the speed of development of efficient shipbuilding methods. Increase in device operation time due to busy assembly processes and complicated site conditions are easily exposed to accidents during operation. Many devices currently in operation at the sites are as old as 10 ~ 20 years, and there are no monitoring systems installed as safety devices on them. Instead, simple pressure gauges are installed for workers to estimate the loading status of devices. Center of mass detector can see the center of mass of heavy weight not only while lifting but also during transportation, allowing to check loading status of heavy weights. This device converts the pressure of heavy weight detected from equipment into a virtual point in order to indicate the center of mass of the weight. However, this is simply shows the movement of center of mass from the center of equipment in the lifted weight. Though location of center of mass can be checked on a real-time basis during lifting and movement of weights, there are limits in examining land surface status and work stability of special structures. Due to such limitations, equipment operators rely on design drawings in use of the equipment, and in most cases continue with their work based on past experiences without being able to make definite conclusion. This study attempted to examine work stability using minimal information on work conditions obtained from work sites and drawings, assisting work decisions in heavy weight transportation works. First, center of mass on the plane of heavy weight lifted by transporter was found, also with center of mass on space. Also using ZMP (Zero Moment Point) theory based on the data obtained earlier, angles at which the heavy weight is inclined and turned over were calculated according to the surface inclination. In particular, stability of heavy weight moving along the inclined surface was found based on simulation with calculated data. Examination of lifting status, stable lifting location and stability with differing inclination was made possible through simulation only using the data verified from the equipment and drawings provided at the sites. It was also possible to examine work stability using simple simulation prior to work and varying work stability according to inclination of the movement path.