P18414: SOIL Composting Toilet and Urine Management
/public/

Systems Design

Table of Contents

Team Vision for System-Level Design Phase

Intentions & Accomplishments: During this phase of the design process, our team planned to breakdown and identify the unique subsystems of the toilet design. This was necessary to better understand the entirety of the design moving forward. During this phase, our team planned to develop system level documents and analysis, identifying the subsystems individually in order to build the design as a whole.

Functional Decomposition

The functional decomposition for this project has the purpose of defining and classifying the subsystems of the dry toilet as a whole. It was necessary to first define the main function of the project, providing a sanitary toilet system, and from there, the subsystems could branch from. As the breakdown tree continued to branch further into the subsystems of the device, the defined functions became more simple and the decomposition of the toilet became more clear. This diagram will help to identify each of the toilet subsystems that need to be considered when furthering the design.

Below is the finalized functional decomposition tree for your viewing pleasure.

Functional Decomposition

Functional Decomposition

To design this breakdown, our customer requirements mapped to our engineering metrics were considered. The link to our House of Quality can be reviewed below.

House of Quality

House of Quality

Benchmarking

Although initial benchmarking was completed during the problem definition phase, benchmarking was also completed during this phase of the project. While in the problem definition phase, benchmarking was done to identify similar toilets as a whole, in this phase of the design benchmarking was completed more specifically. SOIL, our client, asked for a new and improved urine diverter, so our team benchmarked on characteristics of multiple existing urine diverters to identify the best attributes to include in our design. Even though it is important to our client to have a properly functioning urine diverter, it is also important to consider the toilet as a whole. With this in mind, benchmarking was also completed to identify strengths and weaknesses in different material choices and manufacturing techniques for the toilet.

Images and links to the benchmarking documents can be found below.

Manufacturing Benchmarking

Manufacturing Benchmarking

Manufacturing Benchmarking

Materials Benchmarking

Materials Benchmarking

Materials Benchmarking

Urine Diverter Benchmarking

Urine Diverter Benchmarking

Urine Diverter Benchmarking

During the benchmarking process, outside resources were used. A link to a list of questions which we emailed Concrete Canoe can be found here. We are still waiting for a response.

Concept Development

During the concept development portion of the phase, subsystem components identified in our morphological table were chosen based on their ability to solve the defined problem, and their overall feasibility to the MSD process and our available resources. As a team, we decided upon four toilet system concepts which we would further like to develop.

Urine Morphological Chart

Urine Morphological Chart

Pests and Materials Morphological Chart

Pests and Materials Morphological Chart

The document containing our completed morphological table in its entirety can be found here.

From this table, four concepts were developed using different subsystem components. These toilet system concepts can be seen below.

Concept 1: U Shaped Mold

Concept 1: U Shaped Mold

Concept 2: Otji + Slotted Slope

Concept 2: Otji + Slotted Slope

Concept 3: External Urine Containment

Concept 3: External Urine Containment

Concept 4: Slotted Slope

Concept 4: Slotted Slope

Feasibility: Prototyping, Analysis, Simulation

As a group, we identified a list of phase appropriate feasibility questions along with related testing measures and the relevant engineering requirements that correspond to the questions at hand.

A full PDF of our Feasibility Questions can be viewed here.

The budget assigned to us by SOIL can be seen below along with the accompanying download link.

public/Image 171004 RIT Toilet Design Budget.png

public/Image 171004 RIT Toilet Design Budget.png

Project Budget

To determine the feasibility of our designs, resources outside our team were contacted. A document containing questions about RIT's vacuum forming capabilities can be found here. As well as contacting resources at RIT, capabilities at SOIL were also contacted. Notes from this conversation can be found here. Another diverting toilet manufacturer, Otji, was also contacted. The information for this conversation can be found here.

During the feasibility portion of this phase, it was also important for our team to develop rough plans for how to test each of our engineering metrics. The image for this can be seen below.

Engineering Metrics Test Plan

Engineering Metrics Test Plan

The link to the engineering requirements mapped to unique tests to measure the considered variables can be found here. Because this is a working document that we plan to continue developing into the ahead phases, it is subject to change.

During this phase, we also developed a preliminary prototype to test the feasibility of the slotted slope design.

An image of the prototype can be seen below and the link with preliminary analysis can be found underneath.

Slotted Slope Prototype

Slotted Slope Prototype

Slotted Slope Prototype Test Plan

Selection Criteria

In order to determine the ideal concepts to converge on, a selection criteria was established. The criteria was broken down into multiple sections to accommodate for multiple stakeholders. Our selection criteria is broken down into criteria for the customer, design and user, guide and Team T.O.I.L.E.T.

The document for our selection criteria can be found here.

The PUGH tables were made with the intention of comparing multiple subsystem components to the datum, or the component currently in the system that we would like to improve. The PUGH tables include components from the above selection criteria that we identified as relevant to that subsystem. We chose to include both subsystems and the toilet system as a whole in order to identify if there is significant rational to change the design of the toilet. Each of the tables were reviewed both within our team and with our SOIL clients in order to get as much feedback as possible to ensure that we are taking our design in the right direction.

The individual PUGH analysis tables can be seen below.

Toilet Frame PUGH Analysis

Toilet Frame PUGH Analysis

Manufacturing PUGH Analysis

Manufacturing PUGH Analysis

Urine Diverter 1 PUGH Analysis

Urine Diverter 1 PUGH Analysis

Urine Diverter 2 PUGH Analysis

Urine Diverter 2 PUGH Analysis

Toilet System PUGH Analysis

Toilet System PUGH Analysis

PUGH Analyses

Systems Architecture

A diagram of our systems architecture can be seen below:

Systems Architecture

Systems Architecture

Risk Assessment

Although a risk assessment was completed during the initial problem definition phase, as our project progressed, new risks were identified. In order to keep our project properly documented, the new risks were added to the existing risk table, which can be found . As a group, we expect to continue to be adding to this risk table throughout the entire design process. Throughout the design process, we will also keep these risks in mind when deciding upon concepts and finalizing prototypes.

An image of the phase specific risks can be found below along with the link to the running document.

Risks

Risks

Risk Table

Plans for next phase

As a group, we devised a plan going into the next phase. The link to this plan can be found here. The image for the team plan going into the next phase can also be seen below.
Preliminary Detailed Design Team Plan

Preliminary Detailed Design Team Plan

Individually, we each created our own plan. These plans build upon the ones we had previously created for going into the systems design phase. These reports also contain statements on the work we each did as individuals during the systems design phase, as well as a statement on what we each learned during this phase. The individual project plans can be seen below.

Jeff

Chris

Rozie

Nicole

Tessa


A complete list of documents can be found in the following directory: Systems Level Design Documents

Home | Planning & Execution | Imagine RIT

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

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