Nathan Chan A2S1 Robotics and Mechanics 2014-15 Project 2

Project 2 – Lego Originality


Hi, welcome to my Project 2 Robotics and Mechanics Blog! In this blog I will keep you guys posted with every thing I do to create my second project. This project is a summative assessment which I will take more seriously that my first Project, which was on SumoBot or stairclimber which I chose SumoBot. As the first project, it was a given assignment that we had to do SumoBot or Stairclimber however on Project 2, we can do anything we want. Thats right, Lego Originality. This Project seems much more serious and is more serious than the first one, it will probably take more than 13 classes to finish the final product, but I think we will have more time than that. This project will be done in partners and it is not an individual project. For this project I chose Matteo as he really wanted to work with me because he has less experience with legos compared to others in the class. Although he does get distracted sometimes, if I give him this chance to work with me, I think that he will do what is expected. I am currently thinking about what my next project should be about. A few things I have in mind are Monorail, Train, Dumpster truck, ski lift and a coin exchanger (parody of money exchange). My goal was to add some kind of different mechanism to my project like the air pumping, which is my goal for this project, but may not be achieved depending with what I end up with.


Nathan and MatteoAs this is our prototype that has been accepted by Mrs. Law, it will be hard to explain because you only have brief information about my project. I will try my best to explain it to you. As you can see, on the bottom is labeled our names, which are the parts we individually will be covering. I will be making the conveyor belt and the input of the bill will Matteo works on the output. So first onto my part, I will be connecting wheels with the axels and on the outside I will have a medium gear followed by an idler and so on. These will benefit in the long term, as it will only use up 1 motor. For the input of the source, I will be creating another set of wheels so that the bill is not folded and to make sure everything is running smoothly. On the top of my conveyor belt at the beginning, I will put an ultrasonic sensor so that when it senses someone nearby it will start moving. At the end of the conveyor belt, I will add a light sensor and the conveyor belt will stop a few seconds after the light sensor senses something. After the conveyor belt it will be onto storage. The output is Matteo’s job, which is to make 2 sliders that will activate upon a touch sensor. At the end we will program it so that if it senses a correct 10$ bill (light sensors after conveyor belt) they will be able to choose 2 coins or 3 coins.



Day 1: On day one, me and Matteo thought of an idea on what to build. At the beginning, we chose the topic of a vending machine however, things did start to change after the first class. Once we decided that we were going to do a vending machine, we first drew our prototype and the major mechanisms that this project will require on a piece of paper. I will post a picture below of what me and Matteo drew and what I drew. Our first concept that if we put the bill inside the slot, the ultrasonic sensor will let the conveyor belt move and then there will a be a temporary platform to sense the bill and then the light sensor will tell which motor to drop down of the barrier for the storage. There was one big problem, the whole project could only be used once then needed to be modified.

Day 2: On day two, me and Matteo went to look at how the major mechanisms of other vending machinery to get an idea of how we could solve the problem. We had to use the swirl to lock up the food then when the light sensor senses, it swirls one rotation. The hardest part was making the tubing and the gearing/mechanism we would use for the storage of the food, which we ended up then switching our project to a money exchanger. This period, we got our money exchanger drawn prototype approved right before class ended. During break I ended up building the platform of our project.

Day 3: Today we needed to check with about our project again because we needed to clarify what parts matteo would do and what parts I would do. We also needed to tune up the last bits of our major mechanism on how we would build our project. Towards the end half of the class, we got into building and Matteo built one of his storages whilst I was still building my conveyor belt. They way that we split it out was that, Matteo would do the output and I would do the input, however, his was easier so we made a deal that once he finishes he would start helping me

Day 4: Today was mainly building and trying to really add the major mechanisms inside the machinery. At the beginning I wasn’t sure what type or size of gearing I was going to use and would work so I first put the medium sized gear on the bottom and one on the top so that I would only have to use one motor. This kind of gearing worked, however it was very flimsy and moving the gears forward worked however backwards didn’t. After some reminders from Mrs. Law, I realised that I was able to use the medium gear then the idler and so on…. By the end of class I had just remembered and it was too late to adjust it so I stayed in for break and finished it up, finally it worked!

Day 5: Today I managed my conveyor belt and tried to improve it as much as I can. While I was testing the conveyor belt, I realised that it was very weak and flimsy. It was moving fast for a second then slow and so on…This problem took me a while to figure out, until I came up with that I was able to put the motor in the middle of the conveyor belt to make it stronger which it did! Next class I will build the input slot and the storage for the items after that, well get into programming!

Day 6: Today I basically built the insertion of the bill and the storage. The insertion of the bill was basically something I though that would require some kind of gearing to activate. At the beginning I thought that the motor had to be attached to an idler gear and then adding 2 other medium gears on the wheels where the idler made them both move. This ended up not working as there were unable to connect with each other with the way they are built. I then realised that without any kind of gearing the 2 wheels will be attached and move in the opposite directions. The next step was to built the storage which ended up not being a storage whatsoever. It just ended up being a stopper.

Day 7: This class I improved my input of the bill so that the 2 big wheels were correct in the right position. After doing this is started to program the first part of the programming. I started to program the part where you needed to active within the ultrasonic sensor. This day I didn’t to much because i was mostly waiting for matteo.

Day 8: Today I combined matteo with mine. He was supposed to be done with his last class and we were suppose Td to finish combining last class however he wasn’t working hard and we muffed up. This class we added the opening of the output and combined the 2 by adding another platform and using bricks to add as a wall on the outer layers of the whole platform. By adding the openings of output, we then added the touch sensors. I will be programming after this class at home and doing the stuff. By the way the bricks on the outer wall were completely built by me and matteo was still working this class.

Day 9: At the end of the day we realised that we have 2 more classes this time I started to finish up my programming and next time I want to be finished programming and be able to record next time of how it works. I really needed help this lesson as programming is a big weakness for me

Day 10: Today I was still programming as it exceeded so much longer on what I thought it would. I really tried to work on programming and finished this class. It was really frustrating as Ms. Law wasn’t at class today. At the end of the class I recorded the programming. Matteo did not help me what soever on the programming which made me even more frustrating and he didn’t stay in and basically I had to record everything, after this I will not be giving him my recordings of the videos.


Note: These problems are based off the parts that I have to do all matteo’s problems will be on his blog, I will also post the problems on both of our programming.

Problem 1 – Gearing for Conveyor Belt

The first problem was a minor challenge to solve. The major problem of the gearing was that even though it was able to go forward, the gears were unstable. Some gears weren’t touching that when I moved the gearing backwards they wouldn’t touch causing the others after it not to move because it was a dependent variable. The gearing for this was adding a medium gear on the top and one on the bottom and so on. To solve this problem, I had to look back at what we did before project 1 about gearing and realized that I could us a idler in the middle so that everything will be steady. With the idler, all the gears were stiffly touching and it was running smoothly forwards and backwards going the same direction. I think that this problem would not have appeared if I had plan my major mechanisms better this problem would have raised. After analyzing this problem, the gears didn’t fit with each other because the rise in bricks (with holes) did work and wasn’t built to work with each other. Below I will show more clearly in the picture what I mean. After analysing this problem I realised that the gearing must directly touch each other instead of only touch tooths as if they only have touching tooths, it might be unstable whereas this problem it really affected the out come. With not so many experience with different kinds of gearing, I now understand because in the beginning I though that this wouldn’t be a problem and it would work just fine.

Before                                                                           After

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Problem 2 – Positioning of the Motors

This problem was also a minor problem however I couldn’t solve it so I needed assistance from Mrs. Law. At the beginning when I tested my updated conveyor belt with correct gearing it was unstable and at the beginning I thought that there was something wrong with the battery and somehow if that was true, there was a coincidence that all of the battery powers were out of battery. Asked Mrs. Law then she and I said it may not be a battery problem it could be a placing/mechanical problem. Then I analyzed the problem by spinning the wheels from different axles to see if it was a placement issue. I then realized that in the middle of the conveyor belt, it was easier to push and get in motion even with the same amount of force. I then tried to put this into action and changed the position of the motor in the middle of the conveyor belt, which actually solved this problem, and the conveyor belt was much better and efficient. This took me a while as I had to test everything and making sure that it was a independent variable oresle it might have messed up my conclusions. At the end after solving this I realised that by putting the motor in the middle, if you have some kind of gearing that will make the others move, this will be more affective that having the power in the middle. This is because the wheels or gearing towards the end and front both have the equal amount of power instead of only having the power towards the front if it is positioned at the front or at the back depending where the motor is placed. This problem can help me later on where I can help matteo to put his motor gearing in the middle.

Before                                                                                                     After

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 Problem 3 – Light sensor positioning

This was very hard to solve for me but easy for Mrs. Law, credit to Mrs. Law for helping me solve this issue with giving me a lot of clues on how to solve this. At first I really don’t know why I couldn’t solve this but once I realized the mechanism within this I felt really stupid. So first with the light sensor, I wanted it to face directly down on the conveyor belt so that once the bill is inserted, it will sense the colors. The main problem is that whenever I add the sensor on the axle facing downwards, the sensor will just tilt to the side where it is heavier which means the sensor is unstable and can easily be moved out of position with a slight touch (just to clarify it wasn’t in position). I almost spent the whole class trying to solve this but I gave up and asked Mrs. Law. We solved this problem by adding the axle with the mini circle stick that curves in the end by using the half axle half connecter. This is really hard to explain but once I zoom in on the problem with the photo you will understand. This problem might seem very obvious to solve but I am unfamiliar with most pieces so I needed help. By analyzing this problem I conclude that the sensor is unstable or not balanced in weight causing it to not face directly down and since it is connected with an axle it is easily being moved out of position.

Before                                                                          After

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Problem 4 – Input VIDEO=

This isn’t really a problem, depending on how you determine this issue. This just took me a whole bunch of time to figure out or solve to actually make it work and not make the paper dollar rip and jam the whole thing. I will start off by explaining my thinking process throughout the whole time whilst building this input source. At the beginning I though that I will be able to use the motor with the small axle at the end and use a connecter connected with the half axle half connecter thing and connect that with an idle gear. With the idler gear, I thought that I was able to add the 2 medium sized gears on the top and the bottom of the motor. There were 2 problems with this. 1, all the different sized and everything weren’t compatible, I had to try all of them and 2 the wheels weren’t touching therefore you aren’t able to slip the bill through it. After a while thinking on how to solve this, I tested out using a bigger sized wheel with less bumps on it. Whilst trying this, I had the battery box beside me and I would test every single one and after a whole bunch of testing, I realized that by using friction to move the 2 gears by attaching the motor on one side will be good enough, this way the motor ran smoothly alongside the wheels on the top. In this video below, it shows how the 2 wheels move in opposing directions with friction. ABOVE WHERE THE TITLE OF THE PROBLEM IS STATED, HAS THE VIDEO PLEASE WATCH IT!


I am going to explain this programming on how my programming is working. By anytime if you don’t understand what I am talking, look below on the screen shot as I am not very good at describing stuff. So we first start off with our ultrasonic sensor, we are going to start off with this because I guess its the “base” of my project. Once it senses someone really near to project the ultrasonic will detect it. Once it detects it the whole thing starts running, both of the gears of the input wheeling sources are connected and it keeps moving until it senses something under the light sensor. The light sensor is placed under the conveyor belt and when it senses something above 30 which is the number greater than black. Once it senses something greater than black, the conveyor belt keeps moving if it senses something greater which is any bill, the two touch sensors will activate. Once the 2 touch sensors activate, you are now able to choose any of the 2 options which will give you the amount you want. Below is a picture of my programming.

Bottom Part                                                                                                  Top Part

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How “Stuff” Works? Video=

So in this video I will basically be repeating what I have stated above on the programming except all of it will be shown in a well edited video by me. Note that I won’t be giving any of my work to matteo because he did not help me and did not want to stay in for break. So basically in this video it shows the input and the output of our project. The input shows where the bill goes in and then it stops when it reaches the light sensor, the touch sensor activates moving the motors. The video will be shows up here.

Final Product

Here is my final product, I have spent a lot of time working and editing on this project, I really hope you have enjoyed reading about my project and my work. Once again thank you! Here is the video and the photos of my final product. The photos will be in the Gallery!


Photo Gallery (All my photos!)

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