Cartesian Motion System

Designing, drawing, 3D printing, assembling, and programming a 2.5 DOF System

Apr. 30th, 2022

Nathan Sun

Team Members:

Nathan Sun

Zizai Ma

Peng Qiu

Zhonghao Wei

Background and Purpose: 2.5 DOF System

Our target was to design a system with 2.5 cartesian degrees of freedom (DOF), meaning it would have to be able to move in two linear directions, and have functionality for one of the directions. Utilizing 25mm by 25mm Aluminum extrusions, the system is required to have electric controlling components and need to fit into a backpack. Originating from our own previous thoughts, we decided to design a moving target that moves and flips back when it is hit. It will be able to move in x and y directions, carrying the target around, while the target is controlled by an open loop: after it gets hit, the x and y coordinates will reset to a random position and the target will kick back.

Week 1: Brainstorming our design, drawing sketches and making tweaks

Upon receiving project requirements and parameters, we quickly began with brainstorming possible designs and solutions for our target system. Eventually, we decided that the x linear stage will be supported by 2 NEMA 17 motors on two seperate rails, with 3-D printed end holders to hold the motors and the extrusion rails. The motors will use rubber belts to drive the x axis slide, which carries the y linear stage components and the target. The y linear stage will be powered by a single NEMA 17 motor and belts to control the height of the target components, while the target will use a rubber band and MG 996R servo motor to achieve the funciontality of hit feedback and target reset. We made sketches of the entire system and individual parts for future CAD designing.

Week 2: Making and assembling CAD parts to validate designs

On the second week, we came up with our first prototype parts and put them into assembly. The process of evaluating through CAD assemblies was very important to us, because it helped us to systematically locate compatibility and design issues that can be hard to diagnose by themselves. We managed to simplify and apply modular design to the design of the x axis slide, and countless minor design and dimension fixes to the other parts were also applied.

Week 3: 3-D printing parts for x and y linear stages, and making revisions to parts in the actual assembly

Third week was when we began turning designs into parts in our hands, and had an achieved x linear stage control. We further improved designs before printing them, and our 3-D printed parts were mostly successful in their functionalities, with only a small portion of them needing some slight sanding to fit. As shown on the video on the most right above, both NEMA 17 motors were powering the x axis slides to move horizontally. The Makerbase MKS V1.6 board was utilized for motor controls.

Week 4: Finalizing the 0.5 DOF design, assembly of all parts, programing and fine-tuning the software controls

In week 4, we refined the target components (the 0.5 DOF designs), completed all assemblies, developed the open loop controlling software, and fine tuned the codes to ensure high accuracy of the movement. The assembly was neatly wire managed to a tight package.

Partial Code

Key Takeaways

Redundancy Designs

Design with redundencies and unified standards to prepare for unexpected future use, no matter it is putting a few more holes in an array, or leaving reasonable tolerances to your fiting parts.

File and Timeline Organization

We carefully managed our file and jobs to ensure that the entire project runs organized. We kept files names formatted so that other group members know where and what to look for. Small things such as putting the outdated files in a seperate folder, or naming changed parts with a version number greatly increased our efficiency.