Preliminary Project Plan

By Martin Diaz (Project Manager)

Adan Rodriguez (Mission System and Test)

Moses Holley ( Electronics and Control)

John Her (Manufacturing)

Edgardo Villalobos (Solar Manufacturing)

 

WBS

By Martin Diaz (PM),

Adan Rodriguez(Mission,Systems)

 

The work breakdown structure organizes the work needed to complete the project by putting task under each engineer. For our WBS the work of the system engineer was organized into 3 blocks, System Design, Software, and system tests. The work of the ENC engineer was organized into 4 blocks, Electronic Design, Research/Experiments, Microcontroller and PCB, and finally MCU Subsystem and control. The work of the Manufacturing engineer was broken down into  5 blocks, Mechanical Design, Research, 3D simulations, and manufacturing parts and assemblies, and assemble Mini-Pathfinder.

 

Schedule

By Martin Diaz (PM)

The project schedule was created by using Project Libre. Each Task in the WBS was put as task into Project Libre and then the start and end dates were assigned. When a task depended on a other task to be finished first dependencies were assigned. This can be done by clicking and dragging arrows to other boxes. The program will automatically adjust the task.

Burndown

By Martin Diaz (PM)

The Burndown is a chart that shows how much work is left to complete the project vs time.  The Burndown was calculated by moving the task in the schedule to columns in excel and then assigning the percent completion for each task. The ideal percent completion and real percent completion were then plotted vs time.

Power Allocation

By Adan Rodriguez (Mission and Systems)

John Her (Manufacturing)

Moses Holley (ENC)

Edgardo Villalobos (Solar-Manufacturing)

 

The power rating for all of the components on the Power Allocation Report list were calculated using specification sheets of corresponding components. We approximated our mission duration to be 1 hour (one fourth the duration of the Pathfinder’s mission due to our rover being one fourth scale in size). Using the specification sheets to find current ratings of the components, we multiplied the current ratings by one hour to calculate power ratings in milliamp-hours. For the motor drivers, we looked at the power consumption of the IC and divided the operating voltage to get the current draw (0.78W/6V=130mA). The I2C I/O Expander is rated for output of 25 milliamps per pin and we will be utilizing 6 pins implying a total power consumption of 150 milliamp-hours. The Project Power Allocation was set to be slightly higher than the total Expected Power. Note that the Project’s Power Allocation value was used to aid in determining which battery to choose for our mission.

Mass Allocation

By Adan Rodriguez (Mission and Systems)

John Her (Manufacturing)

Moses Holley (ENC)

Edgardo Villalobos (Solar-Manufacturing)

 

Estimates of the 3Dot Board and Custom SMD Board were based off the fact that they are similar in size to the Raspberry-Pi Board (31 millimeters x 66 millimeters). The chassis, solar panel and suspension system were weighed with a scale. Corresponding Sources of expected weights is provided under the Source column. The Project Mass Allocation was set to be slightly higher than the total Expected Weight.

Cost Allocation

By Adan Rodriguez (Mission and Systems)

John Her (Manufacturing)

Moses Holley (ENC)

Edgardo Villalobos (Solar-Manufacturing)

 

The current battery that we intend to buy may be switched out for a different battery after the Mini Pathfinder is built and tested for its power efficiency. About one third of the products that will make up the Mini Pathfinder will be free of charge due to our team members already possessing certain products. Corresponding sources of expected pricing is provided under the Source column. Because the Mini Pathfinder didn’t have a cost requirement the Project Cost Allocation was set to be slightly higher than the total Expected Cost.

Fall 2016 Solar Panels: The Solar Panel Sandwich (the “Encapsulation”)

By Ridwan Maassarani (Design and Manufacturing)

Approved by Inna Echual (Project Manager)

Introduction

In order to secure the cells onto the panel, one must consider the way of “sandwiching” the cells onto place. A rubber substrate was used for insulating the solar cells from the aluminum sheet. Here, I will review the “sandwich” method of encapsulation.

PV Back Sheet [1]

The first substrate considered was PV Back Sheet, which can be bought from aliexpress. This could reduce the thickness of the overall layers and, as explained by Dunmore, a supplier of solar panel material, “the PV back sheet is a photovoltaic laminate that protects the PV module from UV, moisture and weather while acting as an electrical insulator. DUN-SOLAR™ PV back sheets are available in a variety of constructions for both traditional rigid PV modules, like the one shown above, as well as thin film PV modules and solar power concentrators.”

EVA Layer [1][2]

Next, there’s the EVA layer, and according to Dunmore is a “thermoplastic containing ethylene vinyl acetate which is used to encapsulate the photovoltaic cells.” EVA encapsulation might not be the way to go since it needs to be heated which renders the cells inaccessible. And the cells need to be serviceable as part of our project requirement. For our panels, I took a couple of sticker paper and laser cut individual square cut outs to place each cells in its cavity and then when the acrylic is attached, there would be not visual gap between the cells and the acrylic. This did not work since I did not make my sticker paper thick enough. I modeled the shape I needed using Solidworks to ensure every cell in our current design had a cavity to sit in. Then I generated the dxf file that would then be used by the laser machine to cut the sticker paper, as shown in Figure 1.

sticker

Figure 1: Sticker Paper

Then comes the EPE insulations which is an extra layer of insulation, protecting the PV cells from being damaged from additional voltage seeping into the cells and damaging them.

Finally, there’s glass, which was substituted with acrylic in our final product which based on a PDF document written by Arkema, a leading specialty chemicals and advanced materials company says that it transmits 92% of the suns light striking it at the perpendicular.

The entire sandwiching process can be seen in Figure 2.

sandwich

Figure 2: Sandwich Process

References

[1] Solar Back Sheet: http://www.dunmore.com/products/solar-back-sheet.html

[2] Eva Film: http://sinovoltaics.com/learning-center/materials/ethylene-vinyl-acetate-eva-film-composition-and-application/

[3] Plexiglass: http://www.plexiglas.com/export/sites/plexiglas/.content/medias/downloads/sheet-docs/plexiglas-optical-and-transmission-characteristics.pdf