Introduction
There already exists a multitude of walking linkage mechanisms, from the Jensen linkage to the Klann linkage, there is no shortage of mechanisms that achieve this profile. Instead of replicating what many other linkage systems have done, we wanted to tackle a problem more complex while still keeping the theme of walking linkage systems. Therefore, we turned to nature and looked at how other organisms moved. We were particularly fascinated with the spider, with movements that seemed to pivot and shift rather than strut like a typical walking linkage system, and so for our project we decided to mimic the movements as best we can. The biggest issue, is the fact that a spider leg moves with multiple degrees of freedom and in different directions, as such a direct copy would involve knowledge beyond the scope of this class. Instead be decided to approach this goal by combining two different 1 DOF linkage systems in different phases to achieve a similar 3D motion, limiting the scope to contents of our class and also creating a challenge that not only involves the design of linkages, but also the fine tuning of the relationship between multiple linkages using just one input. In summary, our goal is to create the closest representation of a spider as we can, capturing the complex motion profile of the legs using two 2-D linkage systems in parallel to create a more realistic walking motion.
Complexities
Many complexities arise from replicating the walking profile of a spider. Because a spider's leg has multiple degrees of freedom, they are able to move in very complex position profile. Furthermore there are very few resources that are applicable to this situation, and therefore our solution will have to be relatively novel. In order to replicate a spider as closely as possible, there will also be 8 individual legs. Each leg would add another layer of friction and possibility of error, potentially creating issues for actuation, troubleshooting, among many others.
Description of Proposed Mechanism
The proposed mechanism consists of multiple components consisting of a compression system, peeling system, and holder. For the holder there will be a funnel or other constraint that will hold the bottom of the banana in place. The holder itself will likely be curved or of a profile that can facilitate most banana shapes. The primary objective of the holder is to be able to mount uniquely shaped bananas and be able to have a consistent point for peeling to begin. The compression system is simply meant to loosen the skin of the banana at the point where peeling begins. The actual peeling system will consist of multiple duplicate linkage arms that go up and down onto the tip of the banana and pull diagonally downward and away. We will then put all these systems into one structure and combine them to occur in succession at a reasonable speed within one (maybe two) points of actuation.
Scope of Work
For this project we hope to not only be able to completely peel a banana, but also develop a system for practical ejection after peeling and an intuitive peel disposal method. Prior to fabrication, we aim to analyze the material and geometrical properties of a banana, e.g. the structural integrity, average shape, etc. to determine the constraints and dimensions needed for our mechanism. Likely, the most challenging part of this project will be accounting for the general properties of the banana such as its structural integrity and non-uniformity, however it will be exciting to design a solution that is adaptable.
Preliminary Design Ideas
Some preliminary design ideas include using a simple linkage system for diagonal movement of the peelers. For the compression system, a pincer mechanism can be used with softer materials for more grip. For the general construction of the project, most of the parts can likely be made from the laser cutters, with some more intricate parts (such as the contact points for the compressions system) being made using the 3D printers. Ultimately there should not be any need for machining.