P19330: Computer Chassis Cleaner
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Detailed Design

Table of Contents

Team Vision for Detailed Design Phase

Summary:

For the Final Detailed Design Phase, the teams overall goal was to solidify a concept that we can begin building in MSDII. All drawings and schematics for both electrical and mechanical systems should be final and ready to begin construction. All components should be selected, a bill of materials should be created. The risk assessment should be revisited and updated regularly. The schedule will also need to be continuously updated, as well as a preliminary plan for MSDII developed.

Teams Plan:

Tasks Accomplished:

Prototyping, Engineering Analysis, Simulation

Design Concept Flaws

As feared during the previous Preliminary Detailed Design, our concept of a static system of nozzles used for cleaning would not hold. Due to revisiting air flow parameters and using the rating of the shop vac, we came to realize that the shop vac will not have enough air flow for a static system. As shown in the image below, the amount of nozzles we would need would divide the air flow so much that it would either generate a large amount of back pressure or have little to no air flow for cleaning.

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Live document version of the code for calculating air flow parameters is here

Design Concept 2

After this, we brainstormed quickly as a group and generated a second concept. This one was to use a dynamic system involving a moving air column and a guiding track. Due to the dynamic movement of the system, we came up with a Boon Arm to help deliverer air and power while limiting stress on the tubing and wiring.

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Trolley Air Column (Left), Boon Arm (Right)

After going through and trying to design this concept to be manufacturable and deliver the air cleaning pressure and air flow we wanted, we ran into a major flaw. The tracks were not capable of handling such a tight corner with what we had seen. While looking around, the radius of curvature would have caused the inside to be large and a lot of unneeded travel distance.

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Design Concept 3

So we went back to the brainstorming and came up with another concept. This time we would keep the dynamic air column idea but use a XY stage to cover transitional movement inside the enclosure. [Similar to 3D printers]

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From here, the concept is broken down into 4 major parts:

Air Column
The air column will be hung from the rail systems and will have a bevel gear system to help it rotate to keep nozzles interacting with the computer as it translates around the XY grid.

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X Axis Rail System
This rail system will pull the Y Axis Rail System using an axial idea where two belts will pull on both sides of the rail system. Since the two sides will either share a shaft or a bevel gear system, they should keep the same translation rate and keep the system from binding.

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Y Axis Rail System
This rail system will be supporting the Air Column assembly and be supported by the X Axis Rail System. This rail system will be two floating platforms on each side with two rods connecting them. This will ensure a large area for the air column to be supported and keep the rails perpendicular to the X Axis Rail System. Also, the use of 4 linear bearings for support will help in reducing the amount of torque the X Axis will need to provide to move the assembly.

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Boon Arm
As the boon arm was used in the previous concept, we decided to keep it. This allows the system to be supplied air and power with a floating arm above the rail systems. This will allow the tubing to avoid unnecessary bending and pulling on seals to keep the dust from escaping the inner chamber. In more detail, the boon arm will be adjustable in length due to bearing plates that will allow it to extend and retract to the minimum and maximum lengths determined by the rail system.

Drawings, Schematics, Flow Charts, Simulations

Electrical Block Diagram

Block Diagram updated to include Motor Control. Valve controllers were re-purposed to control other 12V Electronics in the system. Some LED indicators and the 120V AC relay will be controlled with 12V logic.

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Schematics

The PCB Schematics are below. They are still in progress. Control for the motors has been added. Valve driving capabilities are still intact as a back-up option. These controller will not be populated on the circuit board if no valves will be used.

Schematics

PCB

The PCB layout is still in progress with the schematic updates. With additional functionality added to the design, (Motor Control), the board is getting a bit busy. However, no functionality has been removed meaning the Valve Control is still an option if required. The board is now 4 by 5 inches. As the remaining connectors get placed, the size may grow a little.

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User Interface

The User Interface has not changed since the last review. More thought is being put into including an LCD Display to tell the user what the system is doing. With the addition of motors, there may be more possible errors to display to the user than the original design. Below is the original User Display shown in the previous review.

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Enclosure Designs

Design 1 was chosen by the customer to proceed with for the construction of the enclosure. This design is with the door opening from the top and the caster wheels will attach to the bottom of the enclosure directly.

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The schematic below is the same enclosure with the cover for the internal frame.

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Side dimensions will be included as some corrections need to be made in terms of the numerical values of said dimensions.

Bill of Material (BOM)

Electrical Bill of Materials

Current Electrical Bill of Materials include all confirmed components for the system. Some specific items are still missing such as enclosure boxes for the AC Electrical Components. The Motors have also not been selected at this time. Below is a screenshot of the Electrical BOM.

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Current Excel Sheet for Electronics BOM here

Mechanical Bill of Materials

This Mechanical Bill of Materials include all of the main materials required to construct the enclosure. A couple of things left in general include the adapter that will attach the vacuum blower hose to the intake manifold of the enclosure and the materials required for how air will be delivered from the vacuum to the interior of the enclosure.

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Current Excel Sheet for Mechanical BOM here

Test Plans

Electrical Test Plans

Some additional test plans were created since the last review.
  1. Motor Test - Verifies that the PCB and code can properly drive the Motors at different speeds and directions
  2. Relay Test - Verifies that the Relay does not get too hot during normal operation so the user does not get burned in case of accidentally touching it's enclosure.
  3. XY Stage Test - Verifies that the code works to move the XY Stage to all required locations and that the motors are strong enough.

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The other test plans are below:

  1. Door Status - Verifies the door switch works properly.
  2. Cleaning Cycle Time - Verifies the cleaning time is within the 1 minute customer requirement.

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Mechanical Test Plans

Previous Test Plans Include:

New Test Plans Include:

Design and Flowcharts

Cleaning Flowchart

With the addition of motors, the cleaning cycle flowchart needed to be updated. Below is the updated flowchart.

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Risk Assessment

Updated Risk Assessment is available in the figure below. New risks were added to the bottom along with possible mitigation plans.

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Design Review Materials

Include links to:

Plans for next phase

A current MSDII Preliminary Schedule is below. Updates still need to be made as risk mitigation is planned.

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Individual End of Semester Plans


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