P16414: Toilet Use Sensor
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Customer Handoff & Final Project Documentation

Table of Contents

Team Vision for Final Demo and Handoff

Finish assembling and testing the entire system.
Complete enough testing to ensure data fidelity of the counter, temperature sensor, and soil moisture sensor.
Review the rate of false positives with Ed and Sarah to ensure an acceptable rate.
Finish waterproofing the box.
Finish Excel macro to display data easily.
Fabricate/solder board if necessary.
Write recommendations for future MSD teams to improve upon our design.
Finish user and build manuals.
Hand functioning prototype off to Sarah.

Test Results Summary

The complete excel file containing the test plans and results can be found at the following link: Test Plans
Battery Life
Voltage Drop of 1 Battery Pack

Voltage Drop of 1 Battery Pack

The above graphs show the change in voltage coming from one pack of 3 AA batteries. The first two tests had the pack powering the ATMega328p chip, SD card, temperature and soil moisture sensors. The third test had all this with the motion and pressure sensors added. This allowed us to ensure that the power drain would not be significantly different with the complete system.

There was not enough time to run the third test as long as the first two, only 9 days compared to the 14+ days of the others. At this point the voltage was 3.8V, well above the 3.3V threshold required to run the sensors. The three tests create nearly identical curves, indicating that they are an accurate indication of the battery life of the system.

Temperature Sensor
High Temperature Test of Sensor

High Temperature Test of Sensor

The above chart shows the testing of the temperature sensor at high temperatures, according to engineering requirement S6. As can be seen, the accuracy of the sensor decreases at higher temperatures, giving a greater error. If the pit contents are composting, an expected high temperature would be 65 degrees Celsius, or 149 degrees Fahrenheit. The error recorded for this value still meets the marginal accuracy requirement. The error shown is assuming that the gun is 100% accurate.

Engineering Requirements

CR ER# Importance Description Metric Direction/Range Target Marginal Comments Test Plans Concluded Condition
1.1, 2.5 S1 9 Percent of new users who detect system % Decrease 0 <5 None S1 Test Plan Unfulfilled
1.2 S2 9 Percent of grid electricity required (any point in system) % Decrease 0 <5 No grid electricity available S2 and S3 Test Plan Fulfilled
2.1, 3.1 S3 3 Time system can be used without interruption days Increase >90 >30 None S2 and S3 Test Plan Fulfilled
2.1 S4 3 Number of data points can be collected by counter number Increase 9999 999 None S4 Test Plan Fulfilled
2.2 S5 9 Detects temperature with reasonable accuracy C Range +/- 1 +/- 3 We don't know the accuracy of the control. S5 and S6 Test Plan Not Complete
2.2 S6 3 Maximum temperature that can be monitored C Increase >80 >70 None S5 and S6 Test Plan Not Complete
2.3 S7 9 Accuracy of pH reading pH Increase +/-0.1 +/-0.5 None S7 and S8 Test Plan Fulfilled
2.4 S8 9 Range of pH reading pH Range 2-10 4-8 None S7 and S8 Test Plan Fufilled
2.4 S9 9 Accuracy of moisture reading % Range +/-0.01 +/-0.1 None S9 and S10 Test Plan Unfulfilled
2.4 S10 9 Range of moisture reading is 0-100% (relative) binary _ yes yes None S9 and S10 Test Plan Fulfilled
2.5 S11 0 Accuracy of oxygen reading % Range +/-0.01 +/-0.1 Unfeasible n/a Unfulfilled
2.5 S12 0 Range of oxygen reading binary _ yes yes Unfeasible n/a Unfulfilled
2.2, 2.3, 2.4, 2.5 S13 3 Frequency of pit readings number/day Increase 24 6 None S13 Test Plan Fulfilled
3.2 S14 3 Number of times the system can be reused number Increase >100 >15 None S14 Test Plan Fulfilled
3.3, 3.7 S15 1 Time it takes to set-up the system minutes Decrease <30 <60 None S15 Test Plan Fulfilled
3.4 S16 1 Time it takes to tear down the system minutes Decrease <10 <20 None S16 Test Plan Not Complete
3.5 S17 3 Time it takes to record data minutes Decrease <10 <30 None S17 Test Plan Fufilled
3.5 S18 9 Cost of equipment to record data USD Decrease <20 <50 Not including laptop or phone n/a Fulfilled
4.1, 4.3 S19 3 Cost of power system over 1 year USD Decrease <15 <100 Based off price of a pack of AA batteries n/a Fulfilled
4.2 S20 9 Cost of total system USD Decrease <400 <1000 None n/a Fulfilled
4.3 S21 3 Cost of consumable parts USD Decrease <15 <30 None n/a Fulfilled
5.1 S22 9 Percent of parts exposed that are not weather resistant % Decrease 0 <10 Internal components do not need to be weather resistant S22 Test Plan Fulfilled
5.2, 5.3 S23 3 Shortest lived part years Increase >3 >1 Fatigue calculation if mechanical part is used. Can be batteries S3 Test Plan Not Complete
5.3 S24 9 Percent of parts that are corrosion resistant exposed to pit % Increase 100 >90 None S4 Test Plan Fulfilled
2.1 S25 9 Percentage of uses the system registers and counts % Increase 100 >90 None S25 and S26 Test Plan Not Complete
2.1 S26 9 Percentage of false positives the system counts % Decrease 0 <10 None S25 and S26 Test Plan Not Complete

Problem Tracking

Problem Tracking

Problem Tracking

Final Project Documentation

The poster can be found at the following link: Poster

The technical paper can be found at the following link: Technical Paper

The electrical build manual can be found at the following link: Electrical Build Manual

The mechanical build manual can be found at the following link: Mechanical Build Manual

The field worker manual can be found at the following link: Field Worker Manual

The Excel Sheet that will convert data into meaningful graphs can be found at the following link: Excel Sheet with Macro

Plans for Next Phase if There was a Next Phase

Eren's Three Week Plan - Eren's Goals

Kendall's Three Week Plan - Kendall's Goals

Kiera's Three Week Plan - Kiera's Goals

Saul's Three Week Plan - Saul's Goals

Quinn's Three Week Plan - Quinn's Goals


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