Motion Sequence Optimization of a Planar Structure

Abstract

The project explores the load-bearing behavior of a planar 9-bar linkage in different states of the ‘effective 4-bar’ reconfiguration sequences based on a robust automated optimization-driven approach of the metaheuristic algorithm, Pity Beetle Algorithm (PBA). Different intermediate configurations depend on the automated optimization-driven analysis, in order to adjust the system’s joints to the desired values during the motion steps involved from an initial to a target position aiming to eliminate the need of multiple actuators. The 9-bar linkage uses a sequence of one degree-of-freedom motion steps by selectively releasing four joints of the primary members at a time and engaging brakes installed on each individual joint and only one geared electrical motor at the base. In the present study, we consider a principal planar 9-bar linkage with initial and target configurations defined on the basis of a quasi-ellipsoid shape of 5.42 and 4.49 m height respectively and 4.66 m span. The objective is to select the optimum motion sequence, in minimizing the brake torques in the locked joints of the structure. The investigation refers to the load-bearing behavior of the structure in all reconfiguration steps under its self-weight. The numerical studies have been conducted with the software MATLAB and Simulink for a Model Based-Design considering the geometrical, mass and inertia characteristics of the planar system. The obtained results demonstrate that the design of reconfigurable engineering structures can benefit from an automated optimization-driven analysis of their sequence selection, from an initial to a target position, for better performance and efficiency.