Team Vision for System-Level Design PhaseDuring the systems design phase of the project our team sought to understand more about how the previous teams design functioned, and see what features could be improved and what could be kept. In order to do this, a plan was developed to run the previous composter to help see the migration of the larvae and the interactions of the larvae with the features of the composter.
The team identified functions for our design and specific components that would satisfy those functions. Analysis of what the main functions of the composter were along with looking back into out customer requirements helped to decompose the functionality of the composter. Benchmarking of possible design concepts enable the team to eliminate specific components that would not be part of the final design. Through this functional analysis we were able to move forward with our morphological chart which aided in the concept selection process.
Feasibility of the project was started by preparing the composter from last years team to be ran. Assessing how well the design of that composter would serve as prototyping for the team seeing as some of the same features were discussed in the creation of our design concept. This is an ongoing process and will be carried over into the next phase to ensure enough information is gathered to help the team create an effective prototype. Risk analysis for this phase has been reevaluated and used to update our master list of risks for the project as a whole. Going through the risks for the project will be an ongoing process as well, and will be updated as new risks are identified.
Function Tree MethodologyThe main goal of the system is Composting Food Waste and is the top box in the Function Tree. The remaining boxes are the functions and inter-dependencies to achieve this goal.
The finalized chart can be seen below. Each level is color-coded and represents increasing specificity.
- Level 1 (Blue)
- Level 2 (Red)
- Level 3 (Green)
- Level 4 (Yellow)
- Level 5 (Purple)
Function TreeFunctional Tree.
Transformation Diagram MethodologyThe transformation diagram displays the inputs (red) of the system and where they are used. It then explains the processing of the inputs (yellow) through a stimulus/response model. From these responses, they are then related to the outputs (green) that they produce.
The inputs used are:
- Food Waste
- BSF Larvae
- Human Labor
The outputs of the system are:
- BSF Pupae
Transformation DiagramTransformation Diagram
Key Takeaways from Functional DecompositionBeginning with the information known about the system, the inputs and outputs, the steps for processing can be brainstormed and related to the known information on either side of the transformation diagram. This creates a stimulus/response model of the system as a whole.
As the inputs and outputs are already known, the most valuable information gained from this exercise is the events that must be facilitated by the composer during processing.
Through this analysis, the group was able to determine multiple key takeaways:
- Food Waste
- BSF Larvae
- Human Labor
- BSF Pupae
- Contain food waste from Gracie's
- Contain Black Soldier Fly Larvae
- Micro-Controller analyzes physical changes of the system
- Larvae begin Pupation
- Remove byproducts from composter
BenchmarkingComparison Table - Controlling Odor
Feasibility: Prototyping, Analysis, Simulation
Feasibility of Given Number of LarvaeLast year's team did feasibility analysis on having 500,000 larvae in the composter. We will do more research into this feasibility in the next phase.
Feasibility of Using Non-Corrosive Material OnlyLast year's team did feasibility analysis on using non-corrosive materials in their composter. We will do more research into this feasibility in the next phase.
Testing Last Year's Prototype
- We are in the process of testing last year's prototype to get a better idea of how their design works, how the larvae behave, and get a first hand look at what needs to change in the next iteration.
- One of the first things we discovered was a risk we hadn't thought about before: not being able to get food waste from Gracie's. On the day we planned on starting our test of the prototype, one of our team members went to Gracie's in the morning to gather food waste, but the food bins were empty. Luckily, when the team went back to Gracie's later in the day there was food waste for us to take so we could begin the experiment.
- When preparing the experiment, we put all the larvae in a bucket and mixed them up with the frass already in that bucket so we could take a sample, weigh the sample, and count the larvae in the sample size, so we could approximate the total number of larvae being put in the composter. An interesting thing that happened when after the larvae were mixed up was they moved into these 5 circular piles. We are unsure why they did that, but it might be something useful to look into the behavior behind that.
Morphological Chart and Concept DevelopmentThe team brainstormed solutions for each function of the composter. Every combination represents a potential solution. With 6-7 solutions for each subsystem, there are over 60,000 full-system design concepts! Not every solution is equally viable. However, they are still beneficial to bolster the creativity process and generate new ideas.
A .pdf copy of the morphological table can be found using the following link: Morphological Chart.
Full-system Design ConceptsWe developed four full-system design concepts using our Morphological Table. These solutions and the previous year's (team 19422) design will be compared against each in the Pugh Matrix.
Concept 1: Cone Shape, Tennis Court Power, Bucket Input, Ramp exit, “Revolving Door”, Bucket, & Adjustable Stand.
Concept 2: Stackable Boxes, Battery Power, Bucket Input, Ramp Out, Drawer Out, Humidifier, & Adjustable Stand.
Concept 3: Inverted Pyramid, Solar Power, Bucket Input, Ramp Exit, Shifter, Tap, & Adjustable Stand.
Concept 4: Half Sphere, Tennis Court Power, Conveyor Belt, Escape Tube & Light, SifterTwo layer Strainer Design, & Adjustable Stand.
- Low Cost
- Low Volume
- Easy to Manufacture
- Easy to operate
- Quick to operate
- Safe to operate
- Easy maintenance
- Ideal Environmental Conditions
- Larvae escape proof
- Larvae migrate properly
- Low larvae mortality rate
- Prevents undesired spills
- Low Energy Requirements
- Low Environmental Footprint
Pugh MatrixPugh Matrices.
ResultsBy capturing the best features of each concept we developed a basis for our prospective prototype:
System Architecture MethodologyThis system architecture diagram is used to show the relationships between individual sub-systems of the final product. Each colored box represents one of these sub-systems and the areas which boxes overlap represent their interactions. These interactions are crucial to product functionality because without them we are left with multiple, individual systems that do not accomplish a new task. System Architecture
Key Takeaways from System ArchitectureThe key takeaways from the above System Architecture diagram for the team are the necessary interactions, or overlaps, between the various sub-systems. Knowing these overlaps, we can now begin to plan and theorize prototypes that optimize the interactions between systems to create a more effective final product.
The interactions that will influence the final design are as follows:
- BSF Larvae/Food Waste
- BSF Larvae/Food Waste/Frass
- BSF Larvae/Food Waste/Leachate
- BSF Larvae/Food Waste/Structure
- BSF Larvae/Structure
- BSF Pupae/Structure
- Food Waste/Structure
- Micro-Controller/Food Waste
Design Test Plans
Operator Safety ImprovementsTo determine if our composter is safer than its predecessors the team will conduct an ergonomic assessment by using:
- NIOSH Lifting Recommendations
- Rapid Entire Body Assessment
- (If time permits) 3D Static Strength Prediction Program Software
Larvae CapacityBefore putting the larvae in the composter, we will take a small sample size of the larvae, weight it, and count them. Then we will weigh the rest of the larvae, add the weight of the sample, and calculate the total approximate number of larvae using the number/weight ratio of the sample to ensure we have approximately 500,000 larvae.
Larvae MigrationWe will calculate approximately how many larvae that are ready to pupate fit in 1 cubic inch and use that metric to count the number of larvae that have climbed out of the composter. We will then compare that approximation to the total number of larvae previously calculated to be in the composter and find the percentage of larvae that have climbed out, and verify if it is equal to or greater than 50 percent.
Food ConsumptionIn order to determine the average rate of food consumption by the Black Soldier Fly Larvae the quantity (weight) of food added will be recorded (in kg). Through observation we will then be able to determine the amount of time required to consume a given quantity of food. By comparing this to the estimated number of larvae added to the system, we will then be able to determine the average weight of food consumed per larvae per unit time.
Optimal TemperatureUsing a thermometer the team will monitor the temperature within the composter. The thermometer will be placed in the compost and left for a couple minutes to give an accurate reading. Immediately after removing the thermometer the temperature will be recorded so it can be compared to the idea values. The temperature within the composter is to be between 25 and 30 degrees Celsius. This range is the optimal range to keep the BSF alive and promote mating.
Optimal Moisture LevelsThe team will monitor the moisture levels within the composter by using the moisture meter. It will be inserted into the compost and left in for a couple minutes to ensure the reading will be accurate. After removing the meter the moisture level will be read and recorded so it can be compared against the ideal values. The goal is to keep the moisture levels between 75% and 85% so the larvae have the optimal conditions to live in.
Risk AssessmentThe following risks were identified in the Systems Design phase:
- Environment for the bugs becomes inhospitable
- Unable to obtain food waste
- Operators get an infection
- Shed gets too hot to work in
- Operators Experience Nausea
- Bees around food compost bins
Design Review MaterialsThe agenda for the systems design presentation can be downloaded using the following link: Agenda.
The systems design presentation can be downloaded using the following link: Systems Design Presentation.