Project Development

 PROJECT DEVELOPMENT

17/2/2022


Our Chemical Device

Our chemical device chosen is the Automatic Disinfection Chamber.

It is used to sanitize a human autonomously and our goal is to be able to fully sanitize the human in the shortest time possible.

Task allocation & Planning

These are our group members and our part for the designing and building process

Do click on the names for the link to their blog and their respective section of the process

Our team made a Gantt Chart to help us plan our schedule and allow us to complete our prototype timely


Gantt Chart link


We also had a Bill of Materials (BOM) for us to source for the items that we needed and along the way, some changes are made and the finalized one can be found here.

BOM link

Design Process

First, we came up with a rough sketch of our chemical device.


From the initial sketch, we made some changes which is the addition of a door and substituting the pump for a spray and a servo and came up with a more detailed sketch





Individual Contribution (Fusion for Structure)

For this project, I will be in charge of the designing of the structure, which we are going to laser cut. 

Firstly, we will be making the base for the prototype. I decided to add slots & tabs so that it will be easier for us to glue the pieces together. Make a square of 256mm x 256mm 


Next, we will be adding the slots for the walls. Make a rectangle of 200mm x 3mm as we are using 3mm acrylic on all 4 sides of the square, making sure that they are equidistant from the edges. In the middle of the square, add a center diameter circle of diameter 179mm which is the ID for the component housing.


This part was very time consuming for me as I had to measure the slots correctly and it took a long time to do all 4 sides.

Next, I will be doing the 4 walls. They consist of the door, the hole for the spray, and 2 walls to enclose it. Firstly, I made the door, which is a 250mm x 250mm square.



Next, we will add the tabs for the wall so that it will join with the slots of the base. The same tabs will be done to all of the walls with is 200mm x 3mm and is equidistant from the edges.


Now, we add the door, which is a 100mm x 70mm rectangle in the middle of the wall.


And our door is finished! The piece that comes out from laser cutting will be our door and we just have to glue an acrylic hinge for it to work.

Now, I will design the wall for the spray. Similarly, we create a 250mm x 250mm rectangle with the tabs like what we did for the door. 

Next, we added the hole, which is a 30mm x 30mm square. I filet the edges with a radius of 7mm to make it look nicer.




And for the 2 walls, it will be 240mm x 240mm with the tabs. I only designed 1 as it can be easily duplicated when we are about to laser cut in CorelDraw.

Next is the rotating base which also acts as the cover for the component housing. It is just a center diameter circle of diameter 184mm.

And lastly, a cover for the chamber, which is 256mm x 256mm.

Now our structure is complete! This is the overview of all the pieces and how our structure looks like when I used the joint feature to combine them all together.


And here is how it looks like after assembling.




Even though it seems easy at first, I found it slightly challenging as there were many things I had to take into consideration that I did not at first, this led to many minor design changes and multiple cuttings, which can be easily avoided. Thankfully, it all worked out.

Problems faced

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. 😠 Therefore we just stuck with our original SG90 servo and luckily, it was barely enough to spray, 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.


As you can see, there are exposed wires despite us trying to hide it in the component housing and 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. I will take all these into consideration  and for future prototypes I will try to make the prototype more presentable and cleaner with no exposed wires.


Finished product



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