P15671: Expansion Joint Health Monitoring Data Acquisition
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Systems Design

Table of Contents

A systems design is the first major step to "engineering" the desired design of our project. Essentially it provides a road map to realizing our design. In MSD I a systems design was performed but included in the systems design was some additional subsystem design. This was due to the fact that in this point of the semester, we were ahead of schedule and found that a subsystem design would be more helpful to perform. The major details of our design were already laid out and decided upon so the natural step was to begin analysis of each individual part.

Functional Decomposition

A functional decomposition is a process that is performed in order to take a more complex process and break it down into smaller, simpler parts. This was performed on the system which is desired to be created throughout Senior Design. Shown below is the functional decomposition that was created for the Expansion Joint Health Monitoring Data Acquisition Package. The system was broken into 4 main components of measuring data, protecting components in an enclosure, developing software to run it, and internal electronic components to make it all work. From these 4 main components the process was further simplified to create a complete functional decomposition.
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Concept Generation

The main functions of the data acquisition package were already determined by this point in the project. We knew we had to measure pressure, temperature, displacement, transmit data, etc. So in order to achieve each of these desired tasks, concepts were generated that could be possibly used. The table below shows different methods to achieve desired functions of our system. The color schemes show possible combinations of each subsystem to create a system with all desired functionality.
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Concept Selection

Once different methods were brainstormed on how to achieve a desired function, each method had to be analyzed in order to decide which method would be used in our systems design. Shown below are Pugh Charts for the different methods to help decide which concepts will be selected. Pugh Charts are tools used to help decide between different methods by making comparisons to a datum on different characteristics of the method.
Temperature Selection:
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Pressure Selection:
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Axial Displacement Selection:
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Radial Displacement Selection:
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Alerting the User Selection:
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Housing Selection:
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Transmission of Data Selection:

Systems Architecture

At this point in the design, rough sketches were created in order to show how the package itself will look along with how it will look when it is mounted on an expansion joint. The package itself will have an LCD screen along with a few simple buttons to perform simple functions such as reset or powering on/off. As well there will be multiple LED's which can be used to alert the user of warnings such as thresholds being exceeded.
Sketch of What the Data Acquisition Package Will Look Like

Sketch of What the Data Acquisition Package Will Look Like

Sketch of How the Package Will be Mounted to an Expansion Joint

Sketch of How the Package Will be Mounted to an Expansion Joint

Risk Assessment

In the Problem Definition Review process, a list of top concerns and risks was developed. This list was further expanded upon to include ranking of importance along with a few other inclusions to the list. This list is shown below.
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Systems Design Review

A systems design presentation was given at the end of Week 6. This presentation can be found at the link below.
Systems Design Review

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