P19345: Model Railroad Control Panel

Preliminary Detailed Design

Table of Contents

Team Vision for Preliminary Detailed Design Phase

For the Preliminary Detailed Design phase, the following goals were included in our team vision:

Throughout this phase we encountered a few unexpected problems. Within our purchase requests through MSD, we did not encompass all cables necessary within a single purchase. As a team, we did not realize we were missing a VGA to HDMI cable for our prototype as it was not provided in our lab workspace, so were required to input another purchase. This caused us to incur unexpected costs due to the extra shipping cost and cost of cables. Another problem we encountered was difficulty with utilizing the monitor / desktop setup with our VGA to HDMI connectors to begin testing the pi zero. This problem was resolved by adjusting settings within the team member's laptop to appropriately connect and display the prototype.

Another concept we are addressing is the open source goal of our design. With a generic design, it is difficult to make something truly generic without knowing all complicated / worst case layout scenarios. As a team, we are comparing our layouts against RIT Model Railroad Club's Niagara layout due to its complex integrations of block detection, routing, and switches. The challenge we are facing is how to allow users to adjust our design to encompass any complex layout, without us as a team designing specifically for a given layout.

Test Bench Prototyping and Simulation

Throughout this phase, one of our primary focuses was our test bench. Our test bench encompasses a functional purpose to allow us to prototype our designs against a model of the RIT Model Railroad Club's current systems. This model also allows us to focus on how our prototype will interact with the club's NCE system, without damaging their existing layout.

The test bench schematic is as follows:

Test Bench Schematic

Test Bench Schematic

From this, the test bench was built to begin prototype testing:

Front of Test Bench Design

Front of Test Bench Design

Back of Test Bench Design

Back of Test Bench Design

Software Concept Design Analysis

Throughout the phase there were discussions about how to design the software. Questions were brought up, flaws were discussed, and smaller details were considered during these discussions. Though not finalized in this phase, the following notes were written to review during the next phase to decide on a "final" design for the software.

Hardware Concept Design Schematic

This is a V1.0 level schematic created for the purpose of determining potential issues when translating thoughts and ideas into hardware. Note that the SPST momentary switches (SW1-SW-16) and the LEDs (D2-D9) will have connections to the Raspberry Pi shield, but will be physically located on the control panel. This schematic was generated using Eagle 9.2.2 Educational edition.
V1.0 Level Schematic

V1.0 Level Schematic

Bill of Material (BOM)

At this point in the project we have utilized $242.98 of our $1,000.00 budget. The majority of items purchased for prototype testing are able to be repurposed and used within our final design implementation. We would like to acknowledge the RIT Model Railroad club for allowing us to create the testbench with items currently in their part inventory. With their support, we were able to construct the testbench from donated items.
Updated Budget

Updated Budget

Test Plans

High Level Test Plan Requirements

High Level Test Plan Requirements


1. Voltage Regulator

2. LED and switch

3. Button Input


1. Pi 3 communicate with Pi Zero(s)

2. Signal Logic

3. NCE Communication

4. Button Input

To view our test plan please click here

Risk Assessment

Within our risk register, we assigned all risks with a letter code. The risks we identified were based off of a 1-3-9 rating, 1 being least severe to 9 being most severe. The ratings were given to the severity of the risk and the likelihood of the risk occurring.

A risk register graph was created to depict where the majority of our risks fall in terms of severity and likelihood, as well as if any risks are added or deleted out.

The Risk Register was assessed to determine if any mentioned risks have been encountered or if their likelihood or severity have changed. As seen below in the risk register graph, risks D and J were re-evaluated and adjusted to show a lower RPN. Risk D reflects the risk "Customer expectations are beyond scope of MSD 1" and risk J reflects the risk "Customer does not understand technical limitations of MSD". With closing the third phase of MSD 1, the two mentioned risks changed in likelihood value from 3 to 1. Also, no risks were completely deleted out of the risk management system only adjusted in RPN value.

Risk Register Visual Interpretation

Risk Register Visual Interpretation

Risk Register

Risk Register

To view our risk register, please click here

Design Review Materials

To access our Preliminary Detailed Design Phase Review powerpoint, please click here

Plans for next phase

In addition to the below WBS section, the following goals are to be completed within the Detailed Design Phase.
Plans for Detailed Design Phase

Plans for Detailed Design Phase

Individual Plans

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