Delayed Toilet Flusher

Purpose:

The purpose of the toilet flusher is to help the child study center keep the toilets flushed by delaying the flush for kids who are afraid of the loud sound the toilet makes when flushing. Some kids would purposely leave a stall unflushed because they are scared of the noise. The delayed toilet flusher flushes the toilet after the user is able to safely exit the stall.

Design:

The inner workings of a toilet tank aren’t very complicated. In our design, the only parts that are relevant to us are the flapper valve, chain pull, and the flush lever arm. The design of the delayed toilet flushed aims to intercept the pre-existing mechanism of a toilet at the chain side of the flush lever arm, where a string will be attached. When the string is pulled upwards, the chain will open the flapper valve the same way as it would when the flush handle is turned. On the other end of the string, there will be a spool that is attached to the servo motor. The servo is controlled by the Arduino. The Arduino is programmed to take input from a button, when the button is pressed, the Arduino will run a loop that first tells the LED in the button to flash as a warning to the user, saying:  “The toilet is about to flush!” Then the Arduino will send a signal to the servo which then winds up the spool, then the toilet will flush.

Timeline:

First week:

During the first week, I completed most parts of the prototype using an Arduino, a servo motor, and a button. The Arduino program was programmed to take the button signal as an input, when the button is pressed, the Arduino runs the loop which then tells the LED to blink with increasing rate to indicate how close the toilet is to flushing, then the Arduino sends a signal to the servo to turn the spool which flushed the toilet.

Second week:

With the software ready from the previous week, week two was focused on building the working prototype. The spool was attached to the motor as well as modified to increase the radius. The prototype was tested on an actual toilet in the science center. Later in the week, we received feedback from the child study center to increase the duration of the warning light. We also received our package from Adafruit. I began to transfer the prototype on to the actual parts, but no progress was made before the end of the week.

Third week:

The goal of the third week was to completely replace parts of the prototype with more refined parts. I struggled to get the button working due to minor differences between our part and the prototype part. But eventually the wiring and programming were debugged and everything worked beautifully.

But for the sake of simplicity, I later shrank the entire apparatus into the picture below.

Arduino Pro Mini on a soldered board.

Hanna made a 3D printed spool to replace the prototype spool, and everything was fitted into the water-proof box we purchased from Adafruit.

Final configuration

End product:

Controll: Arduino Pro Mini

Sensing: Button

Arduino Program of Toilet flush

VIDEO OF REAL TOILET FLUSHING

How it could be improved:

1. The servo mount, currently the servo is hot glued on a PVC pipe that I cut to be a good height for the spool to not hit the bottom or the top of the box.
2. The position of the battery pack is hard to reach when the batteries need to be switched out.
3. The battery pack could be replaced with one single 9V battery, which could be placed in a more accessible spot and be more compact, but one concern is that 1.5V batteries are more accessible in daily life in general.
4. the placement of the hole for the string to go through the bottom is slightly off, which causes the string to rub on the edge of the hole. This could be prevented by drilling the hole that is on the tangent line of the spool that perpendicularly intersects the bottom of the box.
5. Even though the Arduino Mini pro consumes way lower energy than the Arduino UNO, there seems to be a way to cut down the power consumption my even more. http://www.home-automation-community.com/arduino-low-power-how-to-run-atmega328p-for-a-year-on-coin-cell-battery/

Sources that I used throughout the process: (I have consulted a lot more sources but these were the ones that were actually helpful)

Button: https://www.arduino.cc/en/tutorial/button

Input Pullup: Amy! and https://www.arduino.cc/en/Tutorial/InputPullupSerial

Servo: https://www.arduino.cc/en/reference/servo

Calculating torque required: https://en.wikipedia.org/wiki/Newton_metre

Parts: https://www.adafruit.com/

Arduino Pro Mini: https://www.arduino.cc/en/Guide/ArduinoProMini

http://www.instructables.com/id/Program-Arduino-Pro-Mini-Using-Arduino-Uno/  (MOST HELPFUL )