Finding the globally optimal correlation of cranes drive mechanisms

Abstract

Optimization of a multi-drive machine, i.e., a tower crane with a pivoting boom, needs to take into account the interactions between cooperating mechanisms. This article outlines a methodology of selecting optimal mechanism structure from a set of possible solutions. By introducing a certain quality criterion, a set of parameters optimized for the full range of motion is determined for each structure. Thus, obtained parameters can be regarded as optimal and guarantee the best mutual adjustment of interacting mechanisms. Accordingly, each structure is assigned the optimum quality index value. Obviously, this index is associated with the type of involved mechanisms and their interactions, allowing us to find the best out of the sets of optimized cranes mechanisms. The method was illustrated for a one-link crane with lever mechanisms, and comparison was made with rope mechanisms. Optimization tasks were formulated assuming the ideal stiffness of the structure in quasi-static conditions. Effectiveness of the optimization was verified under the dynamic conditions, taking into account rope flexibility. Finding globally optimal design solution will yield the best combination of different mechanisms structures such that the dynamic overload values should be significantly reduced at the stage of design of the steel structure.