P16551: Observer Calibrator
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Preliminary Detailed Design

Table of Contents

Team Vision for Detailed Design Phase

During this phase, we ordered the materials we'll need to begin prototyping the Observer Calibrator. We planned to prepare a prototype circuit with the LEDs we will end up using, but were delayed due to an issue with the MSD ordering system.

During this phase, we also revised our Engineering Requirements, Test Plans, Design Drawings, and Software Plans in accordance with the information we gained from the last Design Review.

We began looking further into stands for the Observer Calibrator, but this is not on the critical path for our project.

Prototyping, Engineering Analysis

During this phase, we planned to prototype the LED array with the actual LEDs we will be using. Due to an issue with the MSD purchasing system, we did not acquire the LEDs in time. However, the prototype developed during the Subsystem Design phase can still be viewed here.

Drawings, Schematics, Flow Charts, Simulations

Below is an updated schematic for the LED array.

Schematic of LED Control Electronics

Schematic of LED Control Electronics

The above schematic was simulated again, and the updated simulation can be seen below:

Simulation of LED Control Electronics

Simulation of LED Control Electronics

From the schematic and simulations, we calculated the individual resistor values for each LED. This was necessary because of the different forward voltage and forward current specifications for the different types of LEDs. The selection of Resistor values is given below.

Selection of LED Array Resistor Values

Selection of LED Array Resistor Values

The CAD models of the integrating sphere have been updated, and are shown below:

Updated CAD of Integrating Sphere

Updated CAD of Integrating Sphere

CAD of Integrating Sphere with Screws

CAD of Integrating Sphere with Screws

Design Drawing of Integrating Sphere

Design Drawing of Integrating Sphere

The housing was redesigned with peg board, to allow easier mounting of the integrating spheres.

CAD Model of Housing with Peg Board

CAD Model of Housing with Peg Board

Design Drawing of Housing with Peg Board

Design Drawing of Housing with Peg Board

Bill of Material (BOM)

We have updated our BOM, and it now includes a potential stand and platform for the Observer Calibrator.

Updated BOM for Preliminary Detailed Design

Updated BOM for Preliminary Detailed Design

With this updated BOM, we mapped out our budget and compared it to the maximum budget allocation. This can be seen below.

Budget Breakdown

Budget Breakdown

Budget Breakdown

Budget Breakdown

Test Plans

LED Luminance Test Plan without Integrating Sphere

LED Luminance Test Plan without Integrating Sphere

LED Stability Test Plan

LED Stability Test Plan

LED Luminance Test Plan with Integrating Sphere

LED Luminance Test Plan with Integrating Sphere

A rough outline of our testing plan for the mechanical aspects of the Observer Calibrator is given below:

  1. Purchase possible elements and measure dimensions to see if part fits, examining schematic for certain components
  2. 3D print any designed parts if needed
  3. Make sure each designed component is ready to build prototype and to be tested by beginning of next semester
  4. Trouble shoot any possible problems

We identified the LED luminance as the critical component for this stage of design. Thus, we developed test plans for the LED luminance before and after creating the integrating sphere. We also added a test plan for the stability of the LED brightness. A link to the Requirements and Testing document, which contains more details on the proposed test plans, is given here

Details regarding the three phases of LED testing are given along the right.

Design and Flowcharts

Below are screenshots from GUIDE, a tool used to create graphical user interfaces in MATLAB. We plan to use this for the researcher interface.

GUIDE GUI Creation

GUIDE GUI Creation

GUIDE GUI Example

GUIDE GUI Example

We also looked at some sample code for controlling the Arduino in MATLAB. This is shown below:

Sample MATLAB Code for Arduino

Sample MATLAB Code for Arduino

Last phase, it became apparent that we may desire to have a user interface for the observer, as well, for alternate use cases. The observer would be able to adjust the primaries in one LED array until they match. An example of a knob usable for such a situation is given below:

Knob for Observer User Interface

Knob for Observer User Interface

Risk Assessment

Below is a screenshot of our latest risk assessment. The risk assessment has not changed, but the due dates for some items have passed due to the delay in acquiring our LEDs. The live document is available here

Updated Risk Assessment.

Updated Risk Assessment.

Design Review Materials

The slides for our Preliminary Detailed Design Review can be downloaded here.

Plans for next phase


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