P18347: Baby Stroller with HVAC
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Detailed Design

Table of Contents

During the final phase of MSD I, team Climate ConStroller worked to finalize their design ideas so they can begin building at the beginning of the next semester. Throughout this phase, the electrical designs and the ventilation system design were completed. It was also discussed where components would be added to the stroller. The BOM was also revised and the team began to order materials.

Team Vision for Detailed Design Phase

Accomplishments
  • Revised the bill of materials
  • Purchased testing equipment and batteries
  • Created a budget analysis
  • Finalized test plans and created a schedule for testing next semester
  • Created preliminary electrical schematics
  • Calculated ventilation system requirements
  • Created a diagram for initial component placement on stroller

Progress Report

Before Thanksgiving break, our team was responsible for writing a progress report for our customer and guide to update them on our project status.

The team's progress reports are posted here.

Prototyping, Engineering Analysis, Simulation

Plastic Cover Prototyping

The front and sides of the stroller were covered with Saran Wrap to simulate the plastic cover that will eventually be attached. This prototyping assisted us in determining some questions that will need to be answered in the next phase such as:

Plastic Prototyping Front

Plastic Prototyping Front

Plastic Prototyping Side

Plastic Prototyping Side

Ventilation Design

A ventilation system analysis was done using Matlab to answer the following questions:

In an attempt to better understand the system and learn how to evaluate the given parameters, students modeled a solution to the layout of a simple, forced convection ventilation system. Flow path was mapped out logically according to increasing temperature and pressure.

Supplemental Simple Forced Convection Ventilation Design

Supplemental Simple Forced Convection Ventilation Design

Maura met with Robert Hudson, RIT alum and ASHRAE engineer, to better understand ventilation design.

Subject Matter Expert Meeting: Robert Hudson (11/29/2017)

Students developed Matlab code to analyze system over varying parameters.

Revision 0: Matlab Document

The system was modeled without a forced ventilation system, this model did not account for the heat given off by the child. The model simply accounting for infiltration from the nylon of the seat and low density polyethylene from the cover. Resulting in a volumetric flow rate of approximately 2.5-3 [in^3/min]. This would require about 13-17 [W] of power to accomplish.

Volumetric Flow Rate within System

Volumetric Flow Rate within System

Following the same system model, the stroller was analyzed to see how long the system would take to reach equilibrium with the outside air temperature. The model looked at the stroller as still being sealed with the heater on. The system would take approximate 82 days to fully lose heat from 74 [deg F] to -40 [deg F].

Time for System to Reach Equilibrium with Outside Air

Time for System to Reach Equilibrium with Outside Air

Drawings, Schematics, Flow Charts, Simulations

Electrical System Schematic

Electrical System

Electrical System

Using the block diagram created in the previous phase along with referencing others work in previous years a mostly complete electrical system schematic has been created. The schematic includes wiring for all of the electrical subsystems.

Software Flowchart

Using the inputs and outputs of the electrical system a preliminary software flowchart was created for the stroller. It uses a series of logic statements to determine what should be done about the internal temperature of the stroller.
Preliminary Software Flowchart

Preliminary Software Flowchart

Location of Components on Stroller

The location of each of the components of the heating system have been mapped out in the images below. These are preliminary locations and are subject to change.
Bottom of Stroller.

Bottom of Stroller.

Front of Stroller.

Front of Stroller.

Handle of Stroller.

Handle of Stroller.

Bill of Material (BOM)

BOM With the continuous changes being made to our system, our BOM was updated as needed. The revised version of the BOM is linked here.

Budget Pie Charts

Cost Pie Charts

Cost Pie Charts

The budget breakdown was made, since budgeting allows us to create a spending plan for our team’s money, it ensures that we will always have enough money for the things we need and planned for.

Test Plans

The test plan was updated and finalized from the previous phase in preparation for MSD II. Each test plan is outlined individually and maps back to an engineering requirement specified in the first phase.

Finalized Test Plan

Finalized Test Plan

Individual Test Plans

Risk Assessment

The following risks will be mitigated through testing in MSD 2.
Risk Assessment: Phase 4 Revisions

Risk Assessment: Phase 4 Revisions

Plans for next phase

  • As a team, what do you need to accomplish between now and the end of the semester?
-Take the feedback from the Detailed Design Review and make any necessary changes or improvements
-Have our team gate review to discuss the work done throughout the semester and discuss how we will start MSD II
  • As a team, what do you need to do to prepare for MSD II?
-Maura will continue to research the ventilation system to ensure it is correct
-Prince will continue to order the materials we have finalized
-The team will take a mental break from the project to return energized and ready to work at the start of MSD II

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