Dynamics, Vibrations and Control Lab Equipment Design

Abstract

Take home lab equipment and hands-on learning tools are still in demand for control theory and vibrations courses. The existing equipment are extremely expensive and require wide lab space. The aim of this research is to build vibratory mechanical system that is compact, modular and small scale so that each student can work on their setup and take it home if necessary. For this purpose, in this study, a semi-compliant mechanism is designed to be utilized in systems control and vibrations courses which would enhance the understanding of students by using experimental demonstration of the theoretical systems. The superiorities of the design over commercially available equipment are their low cost and simplicity. A parallel arm mechanism consisting of several flexible links that can be attached at different points on the slider is designed, finite element analysis (FEA) is performed in Solidworks, and the flexible beams are 3D printed using polyactic acid (PLA) and Polyethylene terephthalate glycol-modified (PETG) filaments. Different configurations of the mechanism are explored by changing the number of flexible beams attached to the slider. The mathematical model of the proposed mechanism can be represented by a single mass and multiple springs in parallel. Since mass is a known property, the equivalent stiffness can be experimentally found from the frequency analysis of free response. For this purpose, a PCB model tri-axial accelerometer is attached to the slider and the equations of motion are derived from the analysis of frequency characteristics of the complaint dual arm mechanism for each configuration. System properties including the equivalent friction are obtained from the acceleration vs time data using logarithmic decrement. The forced response is studied by attaching a load to the mass through a pulley system. The load deflection curve is obtained experimentally from LabVIEW. Since the system parameters are obtained from the free response, Matlab Simulink model outputs for the same initial displacement and force input are verified with the experimental data.