Testing and Results

High Level Requirement #1

 

First, was to have the tub fill within one gallon of the user designated setting. Since the flow rate sensor calculates the water flow in liters, the measurements shown are in liters.  

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Each fill percentage option available to the user was tested, with the maximum fill of 90% being tested three times. Each time the water filling the tub shut off as soon as the sensor detected it passed the target fill number. This led to extremely precise fill levels within half a liter of the desired amount. With the flow rate sensor updating the flow amount every second, this level of precision was possible. 

 

Fill Temperature  

Next, was to have the tub fill with the water within +/- 3 degrees of the user input. Table 3.2 shows the tests conducted with the desired water temperature and the final temperature when the water stops flowing. While all tests fell within that +/- 3-degree range, test number three with a desired temperature of 97 degrees finished at the upper end of the range at 99.95 degrees. Test number two was the only test where the water temperature was below the users set value, but it was still within an acceptable range. 

 

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Water Temperature Maintenance 

Third, was that the tub will maintain the water temperature within that +/- 3-degree range specified during the filling of the tub. Due to the design of the heat pump and the dimensions of the tub, this heat pump can only be used when both the intake and exhaust openings are below the waterline. Therefore, with our tub, this only occurs when the water level is set at 80% or higher. During each test we had to artificially decrease the water temperature by adding ice and cold water to expedite the temperature dropping below the threshold. As soon as the water temperature dropped out of that range, the heat pump turned on and began to heat the water. The table below shows how long the temperature was maintained by the cycling on and off after dropping the water temperature. It is important to note that the times durations shown are when we concluded that test. The temperature could have been maintained longer if left to sit, but for testing purposes, the 15- and 30-minute cycles show the functionality of the heat pump.   

 

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Additive Dispensing Testing 

Lastly, for the dispensing of the additives, prior to the fill testing we tested the individual pump to find out how long they needed to run to dispense 1 oz of the additive. The time measured was 26 seconds of run time for 1 oz, or 13 seconds for 0.5 oz. This was verified during each test as the additives mixed with food coloring to observe then they started and stopped dispensing. The next table shows that during each test, regardless of the additives selected, the 1oz dispense was completed. 

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High-Level Requirement #2 

Fully Drain Functionality 

The next high-level requirement was that the tub would fully drain at the conclusion of each test. With the ball valve that controls the drain defaulting to open, when the on/off switch was toggled off at any point in the cycle, the drain would open. While the table shows that during the official six test the tub drained, it functioned as designed during each of the dozens of fills over the course of troubleshooting the programming and app control. 

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High-Level Requirement #3 

 

Waterproofing Testing 

The final high-level requirement was that there would be no critical failures during the testing. Mixing electronics and water is a tricky business, and good waterproofing was essential to the operation of our product. The main electronics were encased in the IP67 rated waterproofing box. The wiring was run through fully sealed tubing where possible, and the end connections were heat shrink wrapped. At no point in the testing did any failure occur as shown in the next table. 

 

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Low Level Requirement #1 

App Design 

The final requirement was a low level one that the app would be easy to understand and use. An open ended survey of ten people was conducted and while there was feedback given about the aesthetics, the basic functionality was understood and well received.  

 

 

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Summary 

The requirements set were all met within the designated parameters. While there is room for improvement, especially in the aesthetic design of the app, the system performed as designed. Below in figure 3.21 shows the testing results. After a discussion with our advisor Dr. Ejaz, a seventh test was conducted to ensure that filling the tub to 90%, a person sitting in it will not cause an overflow, and all requirements will be met. The test was a success and the tub did not overflow with a 195lb, 6’ 1” man and the system maintained full functionality.