The Almost Fully Recyclable Robotic Arm

Project Overview

The robotic arm midterm has challenged Merrimack College engineering students since the beginning of the robotics class. Students are tasked with creating a robotic arm capable of navigating a 3D space and delivering ten pieces of candy (DumDum lollipops) to oncoming trick-or-treaters. To add an extra layer of complexity, our group decided that our design must be constructed from recyclable materials to promote a more equitable and environmentally friendly product.

Additionally, the team was mandated to produce a commercial marketing the robotic arm and to compose a report for ABET certifications.

Full Assignment Instruction
(AS given by dr Rickey caldwell)

My Contributions

I was responsible for the overall design and construction of all aspects of the robotic arm, coding all lollipop location functions, shooting/editing the commercial, and finally editing all sections of the report.
Feel free to take a peek at our commercial and report to gain a better understanding of what we accomplished.

commercial Report

Thought Process

Many might not consider cardboard as an engineering material, and I agree. However, our analysis revealed its suitability for several reasons:
1. Minimizes Mass: Calculations indicated that cardboard, with a safety factor of 1.5 on the stall torque from Parallax standard servos, was one of two materials suitable for an anthropomorphic robotic arm.
2. Easily Sourced: Abundant cardboard boxes on campus, a result of online orders, minimized costs and proved ideal for cutting out robotic arms.
3. Rapid Manufacturing: Utilizing a Glowforge Laser Printer allowed for quick and precise cutting of our robotic arm from CAD models.
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The overall construction of the robotic arm was relatively straightforward, drawing inspiration from various existing designs. However, my main challenge revolved around determining when to conclude a specific approach. In response to a challenge posed by our professor, I was determined to code the arm using inverse kinematics—an approach involving equations that derive joint angles for a given position.

I had done all the research, taught myself how to model our robotic arm in MATLAB and had a model working where the end effector could follow a line that was plotted from point A to B using an array of angles outputted by MATLAB for each joint.
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Yet that didn't work, our robot using standard servos( servos that rotate 180 degrees) in the configuration that we had it would not function correctly. However, after some simple sketches and brainstorming I found that the robot could follow a parabola(a curved line) but I simply didn't have a enough time(4 days) to figure out how to plot a parabola, access a certain amount of points and then fine tune the system to hit our lollipops each time.

So I pivoted for the best interest of the team. I am proud of the work I did on the code but we would not have been success if I had continued to pursue inverse kinematics.

In the end our 90% fully recyclable, passive end effector robotic arm delivered ten lollipops seamlessly. (see button to left for a video).
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See the robotic arm in action