Mechanical Arm Project

This semester I took Mech003, which is an introductory class for intended Mechanical Engineers at Lehigh University. Throughout the course of this class, some of the things we looked at were particles and rigid bodies in static equilibrium as well as truss and frame structures among other things. As a final group project, our class was broken down into teams and we were asked to analyze and design a model arm as a simple machine that would then be programmed to lift and support a dumbbell at the hand.

human vs model arm

The picture above is what the model arm was supposed to represent: a human arm (triceps, bicep, elbow joint, etc. included) with its functions and forces taken into account and represented as a simple machine consisting of mainly two rigid bodies: an upper arm and a lower arm. Since engineering is about building machines that simplify complex systems, this arm was to be designed in a way that would allow for the human arm to be simplified into a mechanical arm.

In this project, the arm was broken down into two rigid body components and the forces and support reactions were determined by use of free body diagrams and applied principles of equilibrium. By deriving functions of equilibrium in terms of angles that corresponded to different arm positions, the motion of the arm was to be controlled. Once these equations were obtained, a MATLAB code that would produce corresponding forces and reaction values depending on what the angles were was written. As a final task, a dumbbell of weight 5 lbs was actually attached to the hand at the end of the arm and the angles formed and forces calculated were recorded and plotted to see what relationship there was between forces, angles, and distance of the bicep away from the elbow joint.

This project was really interesting because as a bio-engineer major with intentions on pursuing a career in bio-mechanics, it was a great insight into using engineering to develop and replace fractured human limbs. In a team of bio, materials science, and mechanical engineers, I can see how this project could resemble a real-life scenario where you have to work in teams and develop innovative bio-mechanical technology for the medical field. With everyone bringing in different perspectives within their field of engineering (i.e. mechanical engineering members bringing their knowledge of computer programming and thus obtaining the image below), I can see why diversity in the workplace matters. And to think I am learning all of this in my introductory mechanics course!

solidworks arm representation


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