P17062: Keller's Kats Cart
/public/

Detailed Design

Table of Contents

Team Vision for Detailed Design Phase

The Purpose of this Phase


Key Questions to Answer During this Phase

Progress Report

An update on progress toward the detailed design review was sent out on November 21st, 2016. The content was as follows:

What does the team plan to accomplish by the Detailed Design Review?

What tasks have been accomplished so far?

What tasks remain, and who is the owner of each?

What decisions have been made so far?

Drawings and Sketches

Below are a collection of sketches that detail the beginning thoughts and ideas that led to the designs of the top frame rev.3 and bottom frame rev.1 cart designs.

Bottom Frame Design Sketches

Bottom Frame Design Sketches


Top Frame rev.3 Design Sketches

Top Frame rev.3 Design Sketches

Original Bottom Frame Design Concept
Original Top Frame Design Concept
Joint Design Sketches
Top Frame Sketch rev.1
Top Frame Sketch rev.2
Top Frame Sketch rev.3
Bottom Frame Design Sketches

Prototyping, Engineering Analysis, Simulation

Top Frame Cart rev.2 Design

This is the second revision of the top frame cart design. The goal of this prototype was to determine the effectiveness of this frame design on both Trey and Delilah.

The primary modification to this frame from the initial design was the increased height of the frame from the bottom of the wheel, essentially the 'leg' length of the cart. This was done because the original prototype was too small in size for the subjects and resulted in discomfort.

Isometric view of rev.2 bottom-frame prototype

Isometric view of rev.2 bottom-frame prototype


Rear view of rev.2 bottom-frame prototype

Rear view of rev.2 bottom-frame prototype


Side view of rev.2 bottom-frame prototype

Side view of rev.2 bottom-frame prototype


Top view of rev.2 bottom-frame prototype

Top view of rev.2 bottom-frame prototype


Delilah testing the rev.2 Cart Prototype

Delilah testing the rev.2 Cart Prototype


Trey testing the rev.2 Cart Prototype

Trey testing the rev.2 Cart Prototype

Top Frame Cart rev.3 Design

This is the third revision of the top frame cart design. The goal of this prototype was to further refine the cart fit on Delilah and determine any additional design additions or modifications that need to be completed to better suit her. This prototype was not tested on Trey because it was determined to not properly suit her needs and a different cart would be designed to better fit her.

The primary revision to this design was the addition of two supporting frames to each side of the cart. This was done with the intention of improving the overall stability of the cart. The previous revisions only provided support via a spinal aligned rod, which created a torque when the cart was moved. It is believed this causes discomfort for the cat and inhibit fine motor control.

Front View of the rev.3 Cart Prototype

Front View of the rev.3 Cart Prototype


Side View of the rev.3 Cart Prototype

Side View of the rev.3 Cart Prototype


Isometric View of the rev.3 Cart Prototype

Isometric View of the rev.3 Cart Prototype


Bottom-Frame Cart rev.1 (Under Construction)

This is the first revision of the bottom frame cart design. This prototype is still still under construction, but its main goal is to specifically cater to Trey's mobility needs. This is primarily done through the addition of a third wheel that allows the cart to self-balance, allowing Trey to focus on movement and not balancing the cart while she walks.
Front view of rev.1 (incomplete) bottom-frame prototype

Front view of rev.1 (incomplete) bottom-frame prototype


Top view of rev.1 (incomplete) bottom-frame prototype

Top view of rev.1 (incomplete) bottom-frame prototype


Iso view of rev.1 (incomplete) bottom-frame prototype

Iso view of rev.1 (incomplete) bottom-frame prototype


Side view of rev.1 (incomplete) bottom-frame prototype

Side view of rev.1 (incomplete) bottom-frame prototype

Engineering Requirements

Engineering requirements as of 12/7/2016

Engineering requirements as of 12/7/2016

Updated Engineering Requirements document

Bill of Material (BOM)

The bill of materials is shown for each prototype as if each part had to be purchased for each prototype. In reality, many of the materials are re-used between each revision of the cart design so the actual project budget is lower than the sum of all of the bill of materials.
Bill of Materials for the Top Frame rev.2 cart

Bill of Materials for the Top Frame rev.2 cart


Bill of Materials for the Top Frame rev.3 cart

Bill of Materials for the Top Frame rev.3 cart

Test Plans

(#) Denotes areas of priority

Top Frame rev.2 Testing Notes and Observations

Trey Notes

Delilah Notes

rev.2 Solutions

Notes and observations of Revision 2 of Cat Cart prototype

Top Frame rev.3 Testing Notes and Observations

This cart is only intended to be tested on Delilah, there is a Bottom Frame cart currently under development for Trey to use.

Delilah Notes

rev.3 Solutions

Future testing will include completing a testing metrics form to better quantify improvements and flaws in current design. Included below is a link to the current revision of the document used.

Testing metrics Form

Testing Media

Below are some links to testing videos that document the fit and performance of the rev.2 prototype

Video of Trey testing the rev.2 cart prototype

Video of Delilah testing the rev.2 cart prototype

Video of Trey walking around without a cart

Risk Assessment

 Risk Assessment of Trey and her Associated Cart Design

Risk Assessment of Trey and her Associated Cart Design



 Risk Assessment of Delilah and her Associated Cart Design

Risk Assessment of Delilah and her Associated Cart Design

Risk Assessment of Trey and her Associated Cart Design

Risk Assessment of Delilah and her Associated Cart Design

Plans for the Next Phase

With the close of MSD I there has been a lot of excellent progress in the development of cart prototypes. During the testing of the third cart revision it was evident that refinement of the harness and better balancing of the cart is necessary for greater successes in testing to be achieved in future revisions.

To facilitate this success, the key goals of MSD II are as follows:

It is expected that multiple cart revisions for both Trey and Delilah will be needed before the design that offers the greatest combination of comfort and usability is experimentally determined.

Imagine RIT Shared Vision

Best Case Scenario:

In a best-case scenario, both cats will be acclimated to the carts enough for easy attachment. Trey and Delilah will move around an enclosure, utilizing the carts in a way that demonstrates their comfort and improved quality of life. People will be able to interact and play with the cats to an extent, due to both cats being social with the large number of spectators. The robust carts will not succumb to any sort of wear-and-tear and become damaged during Imagine RIT. Pet owners will ask a plethora of questions regarding the origins of the designs and how the team plans to “advertise” the open-source carts. People who work for other shelters and/or owners of cats with rear limb paralysis will ask about how to build a cart best-suited for felines in need of improved mobility.

Moderate Case Scenario:

A likely scenario is that Trey will be willingly put in her cart, while Delilah will put up a fight. Due to a lack of complete comfort as a result of minimal time spent in the carts, the cats will take time to warm up and begin to move around. The carts will provide the necessary amount of support and movement to both cats for a time, until the cats either become fed-up for the day or Imagine RIT comes to a close. Parts will not fail, though the cats may tip over or get wheels stuck in some way while moving throughout the enclosure. People will be intrigued by the project and ask questions because animals typically draw a crowd. If the cats decide enough is enough, a video will be played which shows the carts being attached to the cats, and the cats moving and maneuvering freely.

Worst Case Scenario:

In a worst-case scenario, demonstrations will be halted by both Trey and Delilah refusing to be in their respective carts. Neither cat will move and instead flip over or attempt to get out of the harnesses. Printed parts will fail, and/or harnesses will tear as the cats mess around. Trey and Delilah’s obvious discomfort will be evident to on-lookers, as their mid-sections sag due to poor spinal support and their legs/fur become caught in various cart components. Too many people around the cats makes them uncomfortable and even defensive, and Karla will take them home, leaving any demonstrating to a pre-recorded, looping video. The carts will be deemed a failure, the team’s efforts will have been for nothing, and over-priced carts will still be the only option for owners of paralyzed cats and kittens.

Elevator Speech

Our team’s senior design project challenged us to create a cart which would allow cats with little to no use of their back legs the opportunity to move around normally. Two designs have been created for two different felines with different types of paralysis. Trey is a cat born without any use of her rear legs, so her cart is designed such that she is supported the entire length of her torso by a free-standing chassis. Delilah has limited rear-leg use due to a neuro-muscular issue, so her cart supports the rear portion of her body in a way which encourages the use and development of her rear legs, similar to the function of training wheels on a bicycle. Both designs have their merits and are meant to be open-source, low-cost, do-it-yourself designs which accommodate a large spectrum of cat sizes.

DDR Presentation Action Items

All of these action items are intended to be completed before the week 5 review of MSD II.

Gate Review Documentation

Below you will find links to all of the relevant material for the MSD I Gate Review.
MSD II Plan
5 Week Shared Vision
DDR Action Items
Imagine RIT Shared Vision
MSD I Post Mortem
Problem Tracking
Test Plan

Home | Planning & Execution | Imagine RIT

Problem Definition | Systems Design | Preliminary Detailed Design | Detailed Design

Build & Test Prep | Subsystem Build & Test | Integrated System Build & Test | Integrated System Build & Test with Customer Demo | Customer Handoff & Final Project Documentation