On 21 July, our group met Dr Ho for our second progress meeting. Zann was still sick, so she joined us through video call.
During the meeting
Dr Ho helped us to consolidate the 2 main issues of making our attachment universal, that is,
- Different fans have different fan stand body size (width, thickness)
- The location of the buttons (distance between buttons) are different for each fan
For issue #1, our solution is to make the bar longer and allow it to slide left and right so that the design can fit multiple sizes of fan bodies. This would mean that the bar would sometimes jut out the side of the fan, and may not look aesthetically pleasing, but that is an issue we’ll leave to a later stage.
For issue #2, it can be solved by introducing vertical motion to the part of the attachment that houses the solenoid actuator. The problem we are facing now is how we are going to make vertical motion.
Our requirements for the vertical motion is speed, at the cost of accuracy. Our previous ideas took inspiration from the vertical motion of 3D printers, however the requirements for a 3D printer is accuracy, at the cost of speed. After some surfing on the web and calculations, we realised that the N20 DC gear motor with a M4*100mm screw thread shaft could only achieve a maximum speed (with load) of 4 mm/s (12V, 600rpm). This is an inherent problem with using screw thread shafts, because they are used for precision, not speed. We will continue exploring different ways of achieving our desired vertical motion.
It was also brought to our attention that the power bank that we bought was extremely large and heavy, and might not be suitable for our project. We will look into using other power sources, such as 23A 12V battery, and controlling the voltage as required.
Reallocation of jobs
Now that our coding for the Raspberry Pi integration with our phone’s voice commands is done, we reallocated our jobs (as suggested by Dr Ho) to allow all our members to experience the designing process.
Bryan and Glen will continue working on the prototype with the HDB blocks housing the linear actuators and the bar that pushes the fan’s button.
Zann and Yu Yun will explore how we will achieve vertical motion and work on the design of the prototype.