P19416: Indoor Dry Toilet Base and Manufacturing

Systems Design

Table of Contents

1 Team Vision for System-Level Design Phase
2 Functional Decomposition
3 Benchmarking
4 Concept Development
5 Feasibility: Prototyping, Analysis, Simulation
6 Selection Criteria
7 Concept Selection
8 Systems Architecture
9 Risk Assessment
10 Design Review Materials
11 Plans for next phase

All documents for our Systems Design Phase can be found here. Systems Level Design Documents

Team Vision for System-Level Design Phase

The purpose for this Systems phase of our project was to plan and identify the optimal concept design that we will set as the base for our project. To do this we planned and identified the various sub-system components of our toilet in order to develop an overall design. We then determined the functions of each subsystem. From there we planned to construct multiple designs that met the functions and criteria for the toilet design. Ultimately, choosing a design that is the most efficient and then evaluating it.

To develop our systems design we plan to complete the following:

Functional Decomposition
Improved Benchmarking
Concept Selection

Concept Development
Morphological Table
Pugh Charts
Selection Criteria
Improved Risk Assessment
Systems Architecture
Design Feasibility
Design Flowchart

What we accomplished:

Functional Decomposition
Benchmarking
Concept Selection

Functional Decomposition

The functional decomposition tree shown below list out the functions and subfunctions of our project. This helps us to identify the main functions of the toilet and how each each part of the toilet relates to each other. The specific concepts mentioned is what we will focus on as our overall objective for our project to make improvements on.

Functional Decomposition

Benchmarking

We used the following benchmarking chart to see how our design compared to other toilets. The main ideas that are applicable to most toilets are the same for our current design and the old toilet design of P18414, with a few key differences our design improves upon. The Laveo toilet gives an indication of what the best dry toilet looks like and how it compares to our toilet. Also included are a flush toilet and a portable toilet that we use here, to show how costs and functions stack up to our own. Ideally we want to try to be a similar level with the other models while still staying within the customer requirements.

Benchmarking

Concept Development

During the concept development stage our team identified in our morphological chart different options for the toilets subsystems. Each subsystem included was decided among our team as a possible solution to solve or projects objective.

Morphological Chart

From the morphological chart, 6 options shown below were developed from each members combination of subsystems that they believe would best solve the problem.

Concept Options

Visuals of the toilet concepts can be see below.

Concept 1

Concept 2

Concept 3

Concept 4

Concept 5

Feasibility: Prototyping, Analysis, Simulation

To determine whether an option is feasible, we all came up with a question that would best be answered to figure it out. In doing this, we were able to decide if an option would work. This is still a growing list of feasible reasons, so this will be continually updated.

Feasibility

Selection Criteria

From the 6 concepts developed individually by each team member we needed to select an option that solves the projects objective. To do so, we developed a selection criteria chart consisting of requirements we believe our system should meet.

Selection Criteria and Reasoning

From here we compared each concept option by determining how efficient each subsystem will work for our listed functions and how each meets the requirements from the selection criteria. We did this by creating a pugh chart that illustrates each concepts ranking on how well it meets the function and selection criteria requirements.

Each member had a chance to rank each concept solution by rating it's subsystems either with a 1, Agree/support 0, Neutral or (-1), Disagree/ Do not support. Our rankings were then calculated with an average between both pugh charts and we were able to conclude that the best option was option 5 shown below for Choice 1.

Concept Ranking

Concept Selection

After analyzing various designs for our project we were able to conclude that the best design was Concept 5.This consisted of comparing how functional the design was based on the functions determined that were the most important. Additionally, we also compared in a additional Pugh chart the criteria concepts we selected for our project.As a result, this design was chosen because after completing the Pugh charts we were able to find that Concept 5 had the highest average for the sum of both Pugh charts created(seen here).

Concept 5

Systems Architecture

The image shown below is a general layout of how the toilet would be used. What isn't shown is the use of the powder to mask the odor from the bucket.