Blog 6 Capstone Project Update

Hello everyone,

Once again, we’re here and moving full speed ahead!

The progress made between August 6 and September 20 has been crucial. From a technical standpoint, the heating pad is nearing its final manufacturing stages, with only a few components left to solder and assemble before testing can begin. We've made significant improvements to the design, such as switching from threaded to through holes for better adaptability. Meetings have led to refinements that align more closely with our project needs.

Major milestones include powering up the fan and modifying the enclosure by adding a hole to route the fan's cables for control via Arduino. We're also working on controlling the heating pad using pulse-width modulation. Code revisions are ongoing, and we've had productive discussions with Professor Agarwal, who confirms that we are on track based on his experience. Current tasks include finalizing the prototype design in SolidWorks, controlling the heat output, and completing the fan control code.

For the work period of September 10 - October 13, our team's plan for near term work is to complete further iterations of the fan control code. A first iteration has been completed already, confirming fan functionality by control of a potentiometer. However, the test was conducted via the maximum 5 volt power output of the arduino board, whereas the fan is rated for 12 volts, so a significant reduction in the fans capabilities was present. Regardless, it was a useful test of the mechanism for our forced convection approach.

Additionally, we plan to finish a non soldered version of the entire electrical setup for the device, major components including thermistors, fan, potentiometer, and LCD display. This will allow us to make any potential last minute changes to the circuit before soldering everything together for the final product. Our team will receive the completed manufactured device enclosure and interface plate from the UH machinist.

As always, we will conduct regular meetings with our sponsor to keep him apprised of the project, ensuring we stay on schedule with their and our project plans, while clearing up any uncertainties and obstacles that may arise. As an additional project, we plan to submit a proposal to our sponsor for project funding, per our Capstone professors advice.

The major milestones our team hopes to achieve in our work for this period is the completion of Fabrication and Assembly Milestone, and transitioning into the beginning of the Device Validation Milestone.

The team has successfully Completed the CAD model and are waiting to submit the materials for fabrication and has already started the initial phases of validation. We are hopeful this process goes smoothly, but we anticipate two potential obstacles in the coming weeks: unforeseen issues during fabrication and challenges with validating individual components. Recently, we made last-minute design adjustments based on feedback from the machinist and our sponsor at NASA to ensure everything was prepared for production. If any components are fabricated incorrectly, they will need to be reordered and refabricated, which could affect our validation and testing timeline. To minimize risks, we have maintained close communication with all involved parties. We have also begun executing our validation plan. The team hopes all goes well and every component can be individually validated with no real issues. If there are any complications during validation the team will have to quickly come up with an alternative way to validate the component or device. 

Figure 1: The changes made to the case are highlighted in blue. These include honeycomb-inspired openings for improved airflow and a side opening for the fan wires.

Figure 2: The changes made to the top bread layer are highlighted in red. These include an inner bolting pattern with countersinks for screw placement, allowing the heatsink to be attached as per version 1 from the last blog, and an outer bolting pattern with simple through holes.

Figure 3: This the PCB diagram for the low voltage side of the heating pad. This includes an LED, micro usb adaptor, and a safety switch. PWM will be powered by a regulated 9V battery.