Preliminary Detailed Design
Team Vision for Preliminary Detailed Design PhaseTeams Plan:
- Complete all simulations and analysis to provide proof of concept
- Settle on design specifications
- All drawings, schematics, and simulations should be complete for both electrical and mechanical systems
- Necessary items brought to SMEs for verification
- All components should be selected and a bill of materials generated based off design aspects and budgeting
- Revisit and update documentation
- Create thorough mitigation plans and assign owners to each risk
- Agree on and create test plans for each subsystem
- Electrical schematics created
- PCB layout started
- Updated all flowcharts and block diagrams
- Mechanical drawings (enclosure and manifold)
- Preliminary BOM created for electrical components
- Updated/Revisited Feasibility, Risk Management and Requirements
- Created Test Plans
Prototyping, Engineering Analysis, Simulation
Airflow ModelsBranching Static Divider - divide main flow into smaller sub-branches to provide a field of air flow in the inner chamber.
Intake Manifold - Dynamic control of air flow with the use of valves. This will take the airflow supplied by the shop vac and enable the system to divert it when and where it wants.
From these models, they were simplified and a 7" 1/2" OD tubing was connected to showcase what one 'trunk and branch' would look like. This was then placed into CFD software to try to gain more understanding on our flow parameters.
ME AnalysisDue to limited knowledge of flow parameters, a MatLab code was generated to help in testing and simulation. However, once we found out the parameters generated by the code, we realized that due to supersonic flow the equations and assumptions used are incorrect and invalid for our situation. This is further discussed in feasibility and will serve at a limiting factor in our design work.
Live document version here
Feasibility: Prototyping, Analysis, Simulation
The Valve Controller Chips has limits as to how much current it can sink based on Duty Cycle and the Number of loads it is driving. This was analyzed using the following graph from T.I.'s TPL7407L Datasheet. Due to this, and the fact that the current chosen valves require 350mA per valve, one drive pin from the controller will not work. In the Schematics of circuit board you will see that each valve is controlled by 2 drive pins of the Valve Controllers which can handle the current load.
From the mechanical side of things, our largest feasibility concern is all the unknowns when it comes down to the air flow through the system. Due to rough calculations, we found out that airflow will be at supersonic speeds in the system and current knowledge from the team is limited to sub-sonic flow. Also, if we are not able to branch our air flow into a substantial number of branches, we will not be able to cover the large area of the inner chamber with enough nozzles to have an effective cleaning flow. [The arrow shows the size of 1 branch/nozzle, and this shows the shortest side which is 2.5-3 times smaller than the largest side.]
Consultation of SME's and further research into supersonic flow is required before finalized design and budgeting. Due to the limited time frame for MSD 1, this is the largest concern at this time.
Drawings, Schematics, Flow Charts, Simulations
Electrical Block Diagram
- Updated Block Diagram of the Electrical System is here. A 15 Amp Relay was added to the AC side of the system and the Temperature and Humidity Sensors were removed.
SchematicsThe PCB Schematics are below. They are still in progress. Schematics
PCBThe Board layout is in progress in parallel with the schematics. The current design if 4 inches by 6 inches. It is four layers. All connections should be made easily but nothing is connected at the moment. Currently just working on placement until the schematics are complete.
User InterfaceDue to the elimination of sensors from the system, the need for error messaging is eliminated. Therefore the 7-segment display was removed to reduce cost and simplify the design. Below is the current concept for the User Interface. It has one large Blue button which also has an LED to indicate the system is powered on. It will also have a smaller red LED which can notify the user that the door is open or if another problem is detected by changing how the LED is illuminated, (Blinking or steady).
Two designs were created based on the final concept chosen based on use scenarios.
Design 1 is with the scenario of the enclosure itself being attached via the luggage style of a handle and caster wheels attached to the bottom with a cover opening from the top.
A color code is used to differentiate the different elements involved in the interactions between both the internal and external frames.
The enclosure in both designs is going to be composed of two separate frames with the external frame being the main support for an internal frame which will contain the computer.
The schematic below is the same enclosure with the cover for the internal frame.
To explain the interactions some of the different elements involved:
- The back of the internal frame will make contact with the interior of the external frame. The other sides will have a gap in between to support the electrical and mechanical components of the enclosure.
- The holder blocks serve the purpose of securing the internal frame to prevent it from sliding around inside the external frame.
- The red dots indicate that the top cover will cover the internal frame top only while being attached via hinges from the back end of the external frame.
- The Gap covers serve the purpose of protecting the components that will be inside the gap. It will not cover the gap completely near the bottom to allow for the wiring of the components.
Design 2 is going to be placed on a flat top surface such as a cart where the door will open from the side to slide the computer in.
The same color code will be used for the design of this setup as well.
Some changes compared to design 1:
- The top and back of the internal frame will make contact with the interior of the external frame. The other sides will have a gap in between to support the electrical and mechanical components of the enclosure.
- Similar consistency in terms of supports and internal frame cover and sealant, just different location relative to the external frame as a whole.
- The front side will be the same as the first design.
- The hole is originally drawn to be on the side but can be changed to be in the same position as design 1 if necessary.
- The computer will be orientated in the same way compared to the first design, just different entry point.
The document for both schematics can be found here
Of course, the final design will be chosen by the customer in the Phase end review.
Bill of Material (BOM)
Electrical Bill of Materials
Electrical Bill of Materials with all known materials. Miscellaneous Circuit Board Components will be added to the BOM after Circuit Schematics and Board Layout are complete. These items include (Surface Mount Resistors, Capacitors, Additional Connectors). Wiring is also not included at the moment. This will be added during the next phase.
Live Document for Electronics BOM here
Mechanical Bill of Materials
Not certain of final design or materials
- Aware of materials we can get for free - will try to utilize them as well as we can
- Will use equipment to create components so we will choose raw materials based on machine restrictions, budget and availability
- Once air flow analysis is complete, we will consider 3D printing or vacuum forming certain components
Mechanical Test PlansTest for External Width and Depth
Test for Internal Volume
Other test plans include:
- Weight of entire enclosure
- Noise level measurement
- Sealed enclosure
- Time taken to learn how to use device
- Amount of dust removed after 1 full cycle
- System prep time
Live document for Mechanical Test Plans here
Electrical Test Plans
The Circuit Board will also be tested while the circuit board is being built and populated. All Circuit Board functionality will be tested individually. Once the Schematics are finished, a detailed PCB testing procedure will be written.
Live document for Electrical Test Plans here
Design and FlowchartsA high level concept of how the code will function on the Microprocessor is below. More detailed code flowcharts will be developed once discussion over the best cleaning cycle would run. Meaning controlling which valves and when still needs to be discussed but this current flowchart describes the higher level how the system works.
When considering the mechanical challenges needed for operation of the enclosure, we went back and modified our first ME flowchart to include detail of what we need to accomplish. For here, the hardest complication is that we still do not fully understand the airflow through the system and this is impacting design and budgeting.
Live document version here
Design Review Materials
Plans for next phase
Mechanical Plans for Next Phase
Electrical Plans for Next Phase
Plans for Everyone
Full Current Schedule here
Individual 3-Week Plans
- Jessica Blake's Three Week Plan
- Megan Zielenski's Three Week Plan
- Albert Rivas' Three Week Plan
- Russell Lanzotti's Three Week Plan
- Steven Jacobson's Three Week Plan