Robotics Free Choice Project Blog

Intro: Hello, my name is Alexander Achcar and this is my robotics blog for the second half of the semester. This quarter, we have been building a project of free choice. My partner and I chose to build a hot chocolate machine.

Youtube Inspiration:


Matthew and Alex-1 Matthew and Alex-2



Prototype 1:

We began by building separate parts at the start. I worked on the conveyor belt, whilst my partner, Matthew, worked on the mechanical arm. After the first class, he finished working on the arm, while I had the basic layout, and the wheels set in the conveyor belt. The next day however, we found that after putting the belt around the wheels, that the belt wouldn’t turn without wheels, leaving our conveyor belt useless.

Prototype 2:

After destroying our belt, we recreated it using gears to line the wheels, forcing them to all turn at the same time, of which seemed like a good idea. Later on, when testing we noticed that each time we turned the gears, either it would be really stiff, and not move, or it would instantly snap a smaller gear off, and result in the wheels not in the first row to not even function at all. This led us to question whether our gear design was a good idea. We kept on working on it, this time we took longer bricks and placed them on top of the gear support, which led to the strength of the gear structure. The gears still popped off, however, this time they popped out forwards or backwards, making us have to break apart the belt to retrieve pieces from inside the belt, therefor burning quite a bit of time trying to reinforce. We took this opportunity to delete the program, and start from scratch, this time switching from ultrasonic sensors, to a more efficient, colour sensor to locate the blue mug.

Prototype 3:

We then took apart the entire structure of the belt, this time using a different type of wheels that matched the belt structure better. This ran smoothly the first time we tried to spin the belt. However, we frequently noticed it starting to stiffen, and struggle to turn the belt. This led us to abandon the main structure, leaving us with just a little bit of time. We looked back at our blueprints, and noticed that with the amount of time left, it would be very hard to put together the conveyor belt again. We reviewed the arm, and while trying to program, I realised that the arm didn’t function properly, and needed to be changed. I then deleted the section of the program that functioned the arm. Leaving us with nothing that actually worked, with one period to remain.

Prototype 4:

We completely abandoned our belt, breaking it. However, we took the essential, non-moving parts, including the base of the mixer, which we surrounded with blocks and turned into a new structure, technically creating a new project from scratch. We then decided that with the time due, creating a new mixer would also take time. Thinking back on what an actual, real-life hot chocolate maker did, we used the mixer, and connected a button onto the main structure, turning it into a blender that we could hook onto a larger lego structure, only requiring that you lift it off, then click the button when the blender part is above/inside the cup. We noted that if we put the cup in, we could just have it not move. This led us to putting motors on both side, of which activated with buttons, dropped the components of hot chocolate into the cup. We tested the motor and found it to work smoothly, only needing to have a program to function the droppers.


Problem 1:

The first problem we ran into was when our belt didn’t move, first without gears, leading us to then implement gears into the main structure. We used the gears to attempt to turn all of the inner wheels in unison, which we thought would move all of the wheels at the same time. However, we led to noticing that the gears would snap every time we tried to turn them, leaving the actual mechanism useless in every way besides the actual lego structure that we built. This led us to destroying the entire conveyor belt to start anew.

Problem 2:

Our next problem was not really our fault, however, my partner found that a group from the other period had taken some of our pieces, and had been using our blueprint. At first, this didn’t bother us, but when they took a part of our conveyor belt, we got agitated and became frustrated at the fact that a pair of people we don’t even know had been stealing our work, as well as a portion of our project, which at the time, was desperately needed to make our main mechanism work. We therefor spent time trying to find pieces that were stolen from us, effectively making us waste time.

Problem 3:

Our third problem was the program not working. My program was basically a wait timer functioned to start the program once it noticed something in front of it. Once I actually loaded the program onto a brain, we saw that the actual program didn’t work, and it simply shut off. This made it useless, and while I new how to fix it, we noticed that it was flawed, because if we programmed the mixer to turn, then the mixer itself had to be placed inside the cup, of which it wasn’t, and in contrast, it was above it.

Problem 4:

Generally, our fourth problem was the lack of time that we had to work on this project. We first selected it because we didn’t notice the fact that we could make mistakes in the construction, deemed the easiest part of this project in our heads. Thinking it would be easy, we took our time working on the conveyor belt, not overlooking the gears that were stiff, or broken, of which made our belt not work at all. Then, when given less time to work on the other parts of the machine, we didn’t have the amount of time that we should’ve spent on making our mixer work, of which it didn’t due to the poor structure and weakness of the turning speed. With one period to go, we realised that our project was unfinished, and could use a lot more work.


Video of the Blog:

R&M: Sumo or Stair Climber


I want to choose  a Sumo Bot because I feel like creating a sumo bot will be a lot more fun and customisable. Also, I have done a project with stair climbers in a summer camp last year. Therefor, I’d really like to try something new this year.

DCP_0845   It would be cool to make one like this, but I think it would also be awesome if I could create a different robot that other people haven’t really explored.

A video example is like this, However I’d rather have a larger arena so that movement is more key, therefor developing the element of strategy.