Blog #3

Work Period of March 22 to April 11

During the March 22 to April 11 work period, our team made strong progress in defining the engineering foundation for the Mechanical StairGlide Luggage project and beginning concept selection. Building on the motivation and problem definition from our earlier blogs, we completed Milestone 1 by establishing the project’s key requirements and constraints, including supported load, airline dimensional limits, stair geometry, structural safety, deployment reliability, and pulling-force targets. We also performed baseline stair-pulling tests on a loaded suitcase over more than 20 trials, which showed that stair climbing requires significant user effort and confirmed that wheel–stair interaction and changing contact conditions are major design challenges.

At the same time, the team began work that is still in progress under Milestone 2. We are currently comparing multiple deployable stair-climbing concepts, with particular focus on curved-spoke and standard tri-wheel mechanisms. This phase includes feasibility screening, free-body diagram development, first-order force calculations, and early modeling to determine which concept can best reduce pulling effort while maintaining stability, compact packaging, and manufacturability. In short, the completed work has given us a clear set of design requirements and experimental baseline data, while the current work is focused on selecting the most practical concept for detailed design.

Work Period of April 11 to April 26

For the April 11 to April 26 work period, our team plans to continue work on Milestone 2: Concept Selected, which is currently in progress. During this phase, we will focus on generating and evaluating multiple deployable wheel concepts using feasibility screening, first-order calculations, free-body diagram development, and early CAD modeling. The goal is to better understand how each concept performs in terms of stair interaction, force reduction, stability, and packaging within the suitcase design.

More specifically, we are comparing concepts such as the curved-spoke tri-wheel and the standard tri-wheel while also refining the overall system design, including the frame, wheel arrangement, and folding or locking features. By the end of this period, the team hopes to complete Milestone 2 by selecting the most practical and efficient final concept, supported by preliminary calculations, concept evaluation, and documented design conditions for the next stage of detailed design and prototype development.

Obstacles and Possible Solutions 

Of the obstacles our team will face over the next two weeks, a major one will be developing the frame since it must be connected to the suitcase, foldable, as well as support the weight of the suitcase. This can be overcome by researching and studying existing folding mechanisms, so that we can modify such designs for the particular needs of our device. Looking into the properties of the possible materials will also assist in ensuring that the strength of the frame will hold up against load conditions. Another obstacle we will be facing is ensuring the mechanical advantage portion of the project, where the device will measurably decrease the force needed to pull the suitcase up and down the stairs. Figure 1 showcases the variation in this force on a suitcase with no device attached. One solution to ensure these forces are indeed decreased is for the team to study/calculate at which angles the suitcase would need to be tilted in order to alleviate this strain. 

Figure 1: Baseline Pulling Force Results

Figure 2: Curved Spoke Tri-Wheel FBD 
Figure 3: Standard Tri-Wheel FBD 





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