PROJECT Development

 Project Development

1. The team's chemical device

1.1 What is the device

Our team's chemical device is an alcohol breath analyser. It aims to stop drivers from drunk driving which consequently, will minimise driving accidents on the road. According to the Bankrate, drinking and driving kills more than 10,000 people each year. Hence, the teams' chemical device hopes to alleviate the problem of drunk driving.

The alcohol breath analyser will be able to measure the driver's alcohol concentration in parts-per-million (ppm) and alert drivers on whether they are drunk or sober. The team's chemical device will display the driver's alcohol concentration on the LCD screen. When the driver is drunk, buzzer will sound, red LED will light up and engine represented by servo and gear in our chemical device will stop. When the driver is sober, green LED will light up, buzzer will not sound and engine will start.

1.2 How it works

This is how our chemical device will work:

Instructions:

1. Press the On/Off switch once to start. 
2. Breathe out as per normal into the alcohol vapour sensor through the mouthpiece for 10 seconds.
3. The alcohol vapour sensor will measure the concentration level and either one of the three scenarios will occur.

#1: Concentration < 450 ppm

1. LCD screen will display alcohol concentration value and 'You are sober' message.
2. Buzzer will not sound.
3. Green LED will light up. 
4. Engine will start. In our chemical device, servo will cause gear to spin.

 #2: 450 ppm < Concentration < 750 ppm

1. LCD screen will display alcohol concentration value and 'You had a beer' message.
2. Buzzer will not sound.
3. Green LED will light up. 
4. Engine will start. In our chemical device, servo will cause gear to spin.

#3: Concentration > 750 ppm

1. LCD screen will display alcohol concentration value and 'You are drunk' message.
2. Buzzer will sound.
3. Red LED will light up. 
4. Engine will stop. In our chemical device, gear will not spin.

1.3 Hand sketch of team's chemical device




2. Team planning, allocation and execution

2.1 Team roles

These are my team members' roles.


2.2 Finalised Bill of Materials (BOM)



📎 Finalised BOM Link

2.3 Finalised Gantt Chart



3. Design and Build Process

Part 1: Design and building of gear mechanism (done by Me)

I was in charge of designing the gear mechanism using Fusion360.

These are the steps:

1. Click Utilities > ADD-INS > Script and Add-Ins.




2. Click SpurGear.



3. Set hole diameter as 5 mm.



4. Select bottom plane.



5. (At this stage, I realised that the diameter of the gear hole was wrong so I made changes.) Click Offset > Select the inner hole > Change offset position.



6. Click Extrude > Set distance as -20 mm.



7. Gear is done.






Part 2: Design and building of container (done by Ethan)

Ethan was in-charge of designing the container. The link to his blog can be found here.


Part 3: Programming of alcohol vapour sensor and LCD screen (done by Jing Yang)

Jing Yang was in-charge of programming the alcohol vapour sensor and LCD screen. The link to his blog can be found here.

Part 4: Programming of buzzer, LED lights and servo (done by Wei Ling)

Wei Ling was in-charge of programming the buzzer, LED lights and servo. The link to her blog can be found here.

Part 5: Integration of all parts and electronics (done by Everyone)

5.1 Embedded finalised Fusion360 design

Here is our embedded finalised Fusion360 design with the exploded view.







5.2 Documentation for integration

This is what our final product looks like. 





Here is the video demonstration of our chemical device.


Scenario #1: 'You are sober'




Scenario #2: 'You had a beer'



Scenario #3: 'You are drunk'



5.3 Hero Shot for Integration



4. Problems and Solution

In this section, I will share about the problems that the group faced and how we solved it.

No.

Problem

Solution

1

The initial idea was to rotate the rack 90° to lock the gear in between the racks as the group’s lock mechanism. However, this could not work with a continuous servo and hence, the group had to scrap this mechanism idea.

The group changed the scenario and the gear and servo will represent the engine instead.

2

Gathering of parts that is not available in W3.

The group had to buy an on/off switch that is not available from W3. 

3

The container the group had laser cut did not have holes for the USB port and servo wires to go through. 

As a result, we had to do a last minute troubleshooting and cut out 2 holes on the acrylic container. 





No.

Problem

Solution

4

While putting the parts together, we realised that the on/off switch cannot be conventionally connected.

The group had to perform soldering.








No.

Problem

Solution

5 

Arduino moves about during the process of connecting the USB into the port. 

To ensure that the Arduino does not budge, we used our failed 3D prints from our previous mechanism idea, the rack and pinion gear. We used hot glue to paste the rack onto the acrylic container.






6

The group did not take into account the orientation of the display of the LCD screen. As a result, the LCD screen display is upside down.  

Due to insufficient time, the group decided to change the whole orientation of the whole product. The final product is as shown in the image below.






5. Project Design files as Downloadable files

Here is the link to all the design files (Fusion360 files, .dxf files, .stl files, Arduino programme files) as downloadable files.



6. Learning Reflection

During this whole journey, I get to apply all the skills learnt in CPDD into application to create the group's chemical device. My group and I faced many hurdles from the design phase up to the final troubleshooting of our final product. Along the way, many ideas and suggestions were discarded to create our chemical device. Our chemical device adopted  several changes that differs from the initial idea. For example, the rack and pinion gear mechanism had to be discarded due to servo issue. As a result, most of the Fusion360 drawings that I had painstakingly drawn were not put to use and this was one of the regrets. 

As the group had focused on the programming of the codes and designing of the chemical device separately, some of the important parts to the product were overlooked such as the missing USB port and hole in the container. This also caused the orientation of LCD screen to be wrong which affected the whole arrangement of parts in the container in our chemical device. In future projects, I will make sure to take note of this so as to avoid mistakes in the final integration of all parts. I realised that the group should have physical meetups along the timeline of the project to make sure everything aligns and nothing goes wrong instead of only physically coming together once at the last minute to put everything together. 

During this whole journey, there were many key takeaways from this project that I could put into use in other future projects. I realised the importance of the planning phase and keeping track of tasks to make sure things go accordingly. Although things did not go as planned, I learned that critical thinking and adapting quickly are important skills to complete the project in time.