Abstract:

The future Army officers of the Defense University Center at the Spanish Naval Academy obtain the degree in Mechanical Engineering from the University of Vigo. In this degree, students should acquire a specific competence that involves knowing the principles of machine and mechanism theory. Thus, they must delve into the kinematics and dynamics that govern the movement of the different mechanisms that constitute a machine. On certain occasions and due to their complexity, the kinematic chains of machines require an analysis using the equivalent inertia concept or decompose the study by means of relative motion that simplify the calculation of velocities and accelerations. In certain assemblies, this relative motion is difficult to visualize and it is necessary to use interactive tools that facilitate the understanding of the movement from different points of view.

This article proposes the use of the video analysis and modeling tool “Tracker”, a free software of the Open Source Physics Java framework, to place a mobile reference system in the different links that make up our mechanism. In this way, it is able to interactively visualize the velocities and accelerations of the interesting points. The comparison between the results obtained using this tool and the results calculated theoretically, makes it easier for students to understand the movement of the different kinematic chains. This method highlights the usefulness of inserting a mobile reference system that facilitates the calculation of positions, velocities or accelerations of certain points of interest or centers of gravity necessary to correctly design the movement of a mechanism, taking into account both the geometry of the assembly and the kinematic quantities.

The proposed methodology has been used successfully in practices of the subject "Theory of Machines and Mechanisms", taken by second year students of the Mechanical Engineering degree at the Defense University Center. In this subject, students learn the concepts and tools necessary to face the kinematic and dynamic analysis of a mechanism with different degrees of freedom in a movement restricted to the plane. Positively, the “Tracker” tool allows them to acquire a more realistic vision of the theoretical concepts of relative motion and to better understand the movement of the mechanisms.

Keywords:

Interactive techniques, mechanical engineering, mechanisms, relative motion, kinematics.