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


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.


 


PROJECT DEVELOPMENT 👨‍💻

 

Our Chemical Device: 

Automatic Disinfection Chamber

The aim of the device: Thoroughly sanitise a human autonomously in the least amount of time. 
Inspired by current disinfection chambers and we wanted to solve issues faced with current disinfection chambers.

Task Allocation and Planning

These are our group members with our parts for the design and building process.
Select one of the names to be redirected to their blog.

Our team also made a Gantt Chart to further assist with schedule planning and allowed us to complete the prototype timely.
A Bill of Materials (BOM) was fill in to track our financial spending on the items our group sourced.



Design and Build Process

Sketching of chemical device and mechanisms (Leon)

To start of the design of the chemical device, Leon sketched out the possible designs for the disinfection chamber based on the groups ideas. From the initial design sketch to the final design sketch there were several changes. Most notably was the pump being replaced by the spray bottle and including a door. 

Initial Design Sketch


Final Design Sketch



Design Sketch of Rotating Base System



Design Sketch of Spray System

With the final idea in mind, the rest of the team started to work on fabricating the components necessary to develop 3 important systems. The component housing, rotating base system and spray system. 

More detailed information on the fabrication of the design and building process can be found in my groupmates blogs :)

Arduino Code (90 Deg Servo)

For this project, I was coding the Arduino for the spray system.

The SG90 servo along with an IR sensor and Arduino board will be the components I would need to code for. 

The IR sensor used was a new component that I had no experience coding for. So after a quick google search on how to operate the IR sensor, I learnt that the IR sensor detection range can be adjusted by the potentiometer on the board and also how to code it to be used as an input device for the servo to work with. This video below taught me how to wire the IR sensor to the board as well as code using degrees.



From the video, the code was modified to suit our application for the servo to pull the trigger of the spray bottle.


Explaining the code: 
When object is detected by the IR sensor, it sends signal to the Arduino to wait for 2 seconds before having instruction for loop to be carried out 3 times. Loop consists of servo arm moving forward and back to starting position and that is 1 set. Once 3 sets are completed, loop ends and instruction set is completed. Video below demonstrates the servo code written.




Problems and Solutions

During our prototyping, there were 2 main problems we faced, which is that our servo was too weak to push down the spray and another was the loose USB connection. For the spray, we initially used a different spray bottle which was a push down kind but the servo would get stuck or push the bottle slightly. Thus, we came up with 2 solutions to help us, which were to change the spray bottle and use a stronger servo, which is the MG90S servo. Unfortunately, the MG90S servo that we took was faulty and could not work, and when we switched to another MG90S servo, it was also faulty.  In the end we just stuck with our original SG90 servo. Luckily, it was strong enough to get the bottle to spray a few droplets of water, despite not a very good spray. 

Secondly, our USB connection on one of the Arduino board was quite loose, when we were testing out the prototype, it often disconnected itself even though no one touched it and we had to try various angles so that it would give a connection. We actually made use of a plastic cap like thing to tilt the board at an angle so that it will connect well



For our system integration, it was not very well done as there were exposed wires and the spray bottle was not integrated with the structure.


There are exposed wires despite us trying to hide it in the component housing with duct tape and the spray bottle can move around easily. All these could have easily been avoided if we had made a bottle holder with maybe a tube to connect and hide all the wiring. In future prototypes, I will be more thoughtful of cable management.

Our Final Product