P19014: Portable Upright Walker
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Systems Design

Table of Contents

Content linked here should go in the Systems Level Design Documents directory.

Team Vision for System-Level Design Phase

Goals for this phase
Achievements for this phase

Functional Decomposition

Purpose

Define the total list of functions and sub-functions, based on the Customer and Engineering Requirements, that must be delivered by the final design. This establishes the need for specific concepts necessary to deliver the overall objectives of the project.

Inputs and Source

Functional Decomposition
Functional Decomposition

Functional Decomposition

Function Tree Version 1

Initial function tree with highlighted marks to indicate functions that fall under the add-on device.

Initial function tree draft.

Initial function tree draft.

Function Tree Version 2

Expanded version from first version (link to active document here)

Updated function tree with additional layers.

Updated function tree with additional layers.

Outputs and Destination

Benchmarking

Purpose

Avoid redundant work by identifying already available solutions and concept options. Identify design criteria fulfilled by the existing market.

Inputs and Source

Benchmarking

Preliminary benchmarking analysis can be found here

Problems Identified

Side by side comparison of existing solutions. Active link can be found here.

Side by Side Benchmarking Chart

Side by Side Benchmarking Chart

Requirements

Output and Destination

Concept Development and Selection

Purpose

Input and Source

Selection Criteria

National and International Requirements
Project Requirements

Our selection requirements were primarily determined from our customer and engineering requirements which can be found here.

Morphological Table

The below table indicates a variety of functions with multiple concepts identified.
Morphological table with varying degrees of feasibility for ultimately determining the concept selection.

Morphological table with varying degrees of feasibility for ultimately determining the concept selection.

Concept Selection

The multiple prototypes were analyzed based on a list of criteria revolving around the customer requirements. The analysis was summarized into a net positive or negative value which ultimately becomes a consideration in the concept selection process. Active link can be found here.

 Selection Table

Selection Table

Based on this assessment prototype two (enlarged below) gives us by far the most compliance with our design constraints.

 Prototype two

Prototype two

Features
Possible additions

Concept Assessment

Although our selected concept gives us the best probability for success it is likely that the design will be high cost. One way to improve this is through precise materials selection and looking into low cost manufacturing alternatives.

This design will also likely require revision as we begin to prototype components and more closely compare the prototype test results to our established engineering requirements in fields such as, stability, durability, and maneuverability.

Outputs and Destination

Feasibility: Prototyping, Analysis, Simulation

Purpose

With the facilities available and the experience of Guides will these prototypes be feasible for both prototyping and manufacture.

Materials Selection

Steel

ASTM 1010 Carbon Steel

ASTM A653-09 Galvanized Steel grade 33

Aluminum

ASTM 6061 Aluminum

ASTM 6061-T4 Aluminum

Manufacturability

With the current prototype designs RIT has the facilities to build all attachments. Support will be available through the Brinkman lab and the AM Print Center.
Design Considerations

Tube bending

Material Selection

Mockups

Hardware

Inputs and Source

Gary Hudenius (Brinkman Lab)
AM Print Center

Outputs and Destination

Systems Architecture

Purpose

Assist User Movement while Maintaining Correct Posture
Accomplished by the total system. Each component works together to achieve this function.
Single User Steering
User inputs force along each handle from the brake system location. The user's push is transmitted down each joint of the arms through the legs of the device to the wheel struts. This causes rotational force along the z-axis in the direction desired by the user.
Single User Brakes
User squeezes handle in the upright position. This pulls a wire connected to a spring loaded brake level on the back wheel struts. This causes the wheels to cease rotation and stop the walker.
Provide Comfort
User's arms are held in an upright ergonomically sound location to place minimal stress on sensitive tissue while also allowing them to place a large amount of weight on the device.
Adjustable snaps and locks place the device exactly in the most comfortable position for the user.
Enhance User Mobility
User rotates the device in a manner enabling them to move in a direction and speed of their choosing at any time. This interacts with single user steering and braking systems. User also is able to interact safely with handicap facilities. Cork handles allow prolonged use without user discomfort or injury.
Prevent Falls
User is supported by the "v" angle and wide stance of the device, directing force into the ground and enabling the user to place most if not all of their weight on a safe and stable platform. Wheels lock easily with brake pressure and the arm supports maintain the user's center of gravity is close to the device's.
Encourage Proper Posture
The upright position of the handles forces the user to maintain a more correct posture when walking while not putting a large amount of strain on the body.

Inputs and Source

Outputs and Destination

Designs and Flowcharts

Purpose

To define a high-level view of the elements required to build and operate the entire system
High level view to demonstrate relationships between functions and actions that are then incorporated with the function tree.

High level view to demonstrate relationships between functions and actions that are then incorporated with the function tree.

Refrence: http://edge.rit.edu/edge/P15571/public/Detailed%20Design%20Documents/Data_Flow_Chart_Rev_2_0.pdf

Risk Assessment

Included here is an updated risk assessment table. The main update since last time the risk assessment table was presented was line of sight.

Link to the table can be found here.

Design Review Materials

Include links to:

It is appropriate for you to send your customer and guide a link to this page in preparation for the review. This will ensure that they know what you will be presenting and how to view all of your work. Any EDGE link should start with http://edge.rit.edu/edge/P1xxxx..... Using "http" instead of "https" will ensure that non-RIT stakeholders can view the content without being prompted for a DCE login and password.

Plans for next phase

Plans for Preliminary Detailed Design Review

Team Plan for Next Phase

Team Plan for Next Phase

Team Goal

Our team level goal is to continue working efficiently in order to investigate ergonomics and injury prevention, complete prototyping in CAD, perform component analysis, complete feasibility analysis, and continue to flesh out the chosen concept in the form of drawings, lists, and proper analysis. During this phase it will be crucial for us to do individual work outside of class. In order to successfully achieve our team goal, team members will keep the group updated on their progress for specific individual tasks.

Questions to answer:
  1. What is the chosen design?
  2. Will the chosen design work?
  3. How can we improve the ergonomics of the design to prevent injuries?
  4. How feasible is the prototype?
  5. What does the analysis tell us about the design compared to previous designs?

Individual 3 week plans:


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