Phase 6: Subsystem Build and Test

Our objective for Phase 6 was to perform initial subsystem building and testing, including electrical systems and the mechanical float valve. During the phase, we completed subsystem assembly and some preliminary tests were run with positive results despite some defects with the torches provided to us, namely one of the torch poles had its threads shear away. We've confirmed the viability of our new float valve as well as initial setup of the electrical equipment.

Mechanical Test Results.

Several iterations of the mechanical float valve were made, though due to printer tolerances the quality of the products is variable, and printing related problems have delayed testing of the subsystem. A test setup (Figure A) has been created to determine whether the valve will close itself as intended when the fluid level rises above the height of the valve. Fluid will be pumped into the test chamber through the valve, the expected outcome is the fluid will fill to approximately the height of the valve then the valve will close and stop fluid from flowing.

Figure A: Valve Test Enclosure

The pump that will push oil through the torch system was tested by pumping water through a long tube out a window to ensure the fittings worked and the flow was smooth. Once the team has a stock of citronella oil it is likely this type of test will be repeated to ensure the pump is strong enough to push the higher viscosity oil through the tubing.

Electrical Test Results.

Several tests were run in order to test the viability of each subsystem.  The first piece of the puzzle was to get all the electrical components in one place. This meaning each of the power supplies as well as micro-controllers and the torch pump. Once they were all together they could be assembled to begin the testing of each piece. For this phase the team focused efforts on perfecting the base station laying the initial groundwork for controlling a multiple torch system.

Assembly of the Base Station.

Attached here is the link to the time lapsed video of the base station initial assembly. Here you can see the power supplies have been attached to a sheet of plexiglass. From the power supplies, some easy to use test leads have been attached to expedite debugging. Also to ensure the most safety with using 120Vac the hot lines have been covered with heat resistant wire covers and the initial connections have been enclosed in a small panel box. One future plan is to add an emergency switch. This is an import addition to the system as it will significantly reduce the risk of electric shock which will in-turn reduce our overall risk.

Testing the Pump.

Initial testing of the pump was stopped until the 12V power supply that is necessary to use it was acquired. This did hold the team back for a few days but luckily it arrived in time for some quick initial tests. Another video can be found here. This shows that the pump is capable of sending water from a centralized reservoir up roughly six feet of tubing. This result validates the teams specification of transporting fluids over moderate distances. One issue that may rise from the pump is how powerful it is. As seen in the video documentation the pump takes a moment to get even water to the end of a small hose. This could mean significant delays in fuel delivery or even failure to deliver.

Micro-Controller Initial Programming: Establishing Server and Client Communication.

To test the micro-controllers and get a simple web server running, we set up (1) ESP32 to act as a WIFI access point. This is our server. The other ESP32 device connects to the WIFI access point and are able to access the simple web server to turn on an LED on and off. This will work to help turn on and off the relay which will be controlling the pump.

Early Stage Integration.

To validate the use of a network attached controller in activating parts of the torch system, a relay was added into the system to control the flow of electricity to the pump giving us control of its fluid cycles. This part of testing is still in progress, but with the teams success in controlling the state of an LED through the network, this is simply a task that requires some quick wiring. The figure below shows the configuration of the relay sans fuse.

To Be Done.

Missing from this stage was the solar power for the individual torches. Documentation and tests on the solar power can be found in the MSDI tab of our page. In phase seven, the team will work to integrate the solar power subsystem to power up on of the ESP32 clients for an individual torch.

During this stage, the sensor that will be used to detect the fuel level was also missing. The image below shows the preliminary work on the sensor. The block diagram shows preliminary planning for integrating the individual torches (clients) with the base station (server) which will proceed in phase seven. Values for a "low level" and "high level" will need to be determined based on testing at the start of phase seven before further programming can occur.

Risk Assessment

For phase 6, the team has re-evaluated the risk assessment chart and made some changes. The team has decided to not add new risks but instead modify some risks. One of the major changes was that we decided to lower the importance of getting approval from EHS since we have gotten the clearance to use citronella oil for this project. The other change that we have made is the description for risk 18. We have decided to not go forward with Bluetooth but instead go for a WIFI solution. This was mainly decided because Bluetooth mesh has a lot of requirements and permissions needed to use it. We decided it's not worth to learn and get around all those permissions but rather go with WIFI to show a proof of concept. The other change that we decided to change was risk ID 11, "Limited knowledge of app development and fluids". As we move along with our semester and the phases more work is being done. It's not a huge a blocker as it was previously as we are constantly learning about these new features. It was lowered to a value of 3 importance from 9. 

The changes to the risk assessment led the total importance value to be lowered by 14 from the previous phase. A chart with the importance vs the number of risks is shown at the bottom. It shows how the importance and the number of risks changed over each phase.

Problem Tracking

The team ran into a problem this phase with the valve that was designed didn't exactly fit and had an issue with the threading. Our intention is to modify the valve or the pole of the torch to compensate. The other problem of note that the team has faced is being able to test all the electrical components since we are still waiting on things to be completed. This could lead to problems with subsystem integration in the next phase

Phase 6 Pre-Read: P21389_SubsystemBuild&Test_Preread (2).pdf

PowerPoint Presentation: Phase VI_ Review.pptx

The objective of Phase 7 (System Integration) will be to integrate all subsystems into one functioning prototype and perform preliminary tests of the entire system assembly. At the end of this phase we expect to have a minimum viable product which will be further refined in Phase 8.

Phase 7 individual plans: