Flagpole Linkage Mechanism

Feb 2024

GOAL: convert rotational motion to linear motion through a system of linkages 

SKILLS: CAD (Onshape), wood working, linkage design, wiring, prototyping, use of single board computer (Raspberry Pi), laser cutting, collaboration

The goal of this assignment is to replicate the motion of Mario (or another character) sliding down the flag pole at the end of every Super Mario Bros level.

Design Constraints

Video

Design Process

One thing I really wanted to do was translate a full rotation to linear motion, since it is much simpler and would require less computational resources. There were many examples of translating a full rotation to an arc, and for translating an arc to linear motion so we decided to combine these to get directly from a full rotation to a line. 

First, we made some mock ups out of cardboard and pins

Then, I made the parts in Onshape to validate the design. I first CADed the rotation to arc 3-bar linkage and the Peaucellier-Lipkin linkage (the diamond shaped one) separately. Then, I measured the angles at which the diamond linkage extends comfortably (doesn't overlap itself) and inserted the 3-bar linkage assembly such that the medium sized link of the 3-bar linkage lines up with the small link of the diamond linkage. To find the correct angle of the 3-bar linkage, I positioned it so it reaches the far point of the diamond linkage's rotation when fully extended, and reaches the close point of the diamond linkage's rotation when fully contracted. 

Next, we cut out a mini version of the linkages and assembled it before finally cutting the full sized pieces and putting everything together.

Code

Flag.py

CAD

Challenges

Things to adjust in the future