Project Development
18/02/2022
Project Development
Our Chemical Device:
Due to the Covid-19 pandemic, we wanted to develop a probable solution to solve the issues faced with the disinfection chamber which is the duration taken to completely disinfect takes a while thus our chemical product is aimed to disinfect humans autonomously with the shortest time possible.
To begin off, we had to plan out our schedule and how each portion would be allocated to a different person. A project Gantt chart was developed, as shown below is the project timeline:
Link to Gantt Chart
We also needed to have a BOM (Bill of Material) list for the items we needed to build this product, there are some minor changes in between but the finalized one can be found below here
Link to BOM
Allocation of Work
The building of our Chemical Device was done by everyone.
Design and Building Process
As shown here is our initial design and final design of the chemical device that we will be building.
Figure 1: Initial design
From the initial design, we made some changes to it. Mainly includes the pump which got replaced with a spray bottle instead and having a door at the front now in the final design.
Figure 2: Final Design
Figure 3: Design of Rotating base
Figure 4: Design for Spray Mechanism
For more detailed information do press the links below to my groupmates blog where you can find the relevant section for the design and building process.
Individual Contribution to the project:
Arduino Code (Continuous Servo)
For this project, I am mainly doing the coding of Arduino for our project with Ethan as well as the Fusion360 design for our component housing as shown in Figure 3.
For the code portion, I will be covering the code written for our rotating base which is basically a continuous servo code whereas Ethan will be writing for our Spray Bottle code which is a Servo 90 Code.
To begin off, I had to google and research for a little bit first as it is the first time I am using the 360 Degree Continuous Rotation Servo. After researching I understood a few things, the servo would not stop spinning if the servo.detach(); function is not used when paired with an Infrared Sensor. Another thing is that the FS90R servo that we are using does not have a position sensing element thus it would not be able to read the position if you coded it within the code itself but instead you can control the direction of the servo, either in the clockwise or anti-clockwise direction. To do that you can use servo.write(0); or servo.write(180); to control the direction.
I found this video below that is useful for the code:
By using the code he used I made some minor alterations and eventually came up with the code that we are going to use for our FS90R.
As shown above, is a video of the code running when an object is being sensed.
To access the other servo code that Ethan will be covering do click on the link below:
Component Housing Design:
To begin off, I researched a bit about existing rotating platform designs that are on the internet when I came across this video.
From this video, the creator actually have ready-made files in Thingiverse which can be downloaded and it will be ready for 3D printing, however, we did not actually need some of the components he made, which mainly include the battery holder which we are not going to be using, thus we decided to make the ring of the component housing from scratch and I am tasked to do that portion.
To begin off, I will be using Fusion360 to create the component. Firstly create a circle of dimensions that you want, for us, we are going to be using 179mm.
Next, make an offset of 3mm to the circle that is just drawn.
Then click on the Extrude function by pressing "E" or the icon highlighted in the picture shown below. Extrude it by 34mm.
After extruding the base, we need to create 2 holes for the wires to go through. I made use of the "hole" function highlighted in red, and the settings are shown below on the right side of the picture.
After creating the hole, the ring for component housing is ready for 3D printing.
This is the video that we took while 3D printing it:
This is the finished product:
Problem and Solutions
So moving forward, we just had to stick with the SG90 where we positioned the servo on the bottle such that it still provides enough torque for the spray to actually get pressed down without the servo getting stuck in position, and we also made use of steel wires to aid in the mechanism.
Another main problem that we had was the loose USB connection on one of the Arduino Board which led to the Arduino frequently disconnecting from our circuit and causing the whole system connected to stop working all of a sudden. To fix this issue, we had to find the perfect angle to hold the Arduino Board and prevent it from disconnecting, so we went ahead and made use of a plastic bracket to elevate the Arduino Board at an angle such that the USB connection would connect well without disconnecting.
From the picture above you can actually notice that the Arduino Board is not flat to the base of the component housing, instead, it is elevated at an angle due to the plastic bracket we used at the bottom. This actually helped solve our USB disconnecting issue and our device was able to run smoothly after.
For our system integration, it was not done well as we did not take into account hiding the wires and the spray bottle. This could have been easily done if we cut out another small acrylic box to cover the bottom of our box which is where all the loose wires are found, the small acrylic box could also have covered our spray bottle. However, we were not able to hide the wires and spray bottle better due to the time constraints we had.
Our Final Product
Side view of our product
Front view of product
Demonstration of product
Link to Project Design Files
Final Prototype Design
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