KNOWLEDGES
PROJECT EVOLUTION
MILESTONE 0
19/02/2018
First off we needed a general concept of the workings of our machine. We divided the machine in different zones or parts from the moment the coins go in to the moment they are stored and finally given back. We came up with a tower-like design putting the entry for the coins on top and the receiving end in the bottom, allowing us to use the gravity. This way the use of mechanics mechanisms to sort the coins are an option.
With this in mind we started to debate about each part and we concluded that the sorting/distribution mechanism and the storage zone will shape the machine. We came across a sorting coin concept that we liked and it was circular. This joined perfectly with our storing concept which was also circular. Therefore the shape of our machine started to take form as a cylinder.
After many many sketches and ideas flowing, we ended up with a first sketch for the concept design.
MILESTONE 1
5/03/2018
Things move quickly. Already in CAD sketch design process.
The different mechanical parts were assigned to the members and then simulated using PTC Creo.
This allowed for a simpler way of looking at the concept and to correct some possible mistakes.
The main design that will shape the entire machine is the last one, where the coins are given back. This is because of the coin containers alignment complexity and importance. Therefore the parts above will be build with this in mind.
After some more iterations in the concept design, a final concept design is done and will be followed to the end of the machine. In this design the coin containers will be on the side instead of the center, the assembly will be done from the ground up and there will be an inside part (skeleton) and the enclosure (skin).
Right now materials are being chosen and components listed. Our goals remain the same and specifications about the machine are on the way.
12/03/2018
Specifications:
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
MILESTONE 2
14/03/2018
Milestone 1 done and accepted by the teachers. We had to make small adjustmesnt in the motor torque calculations. The final specifications and goals, the calculations made and the shopping list as well as the conceptual design and other details are in the excel file of the Milestone 1.
​
From here we proceed to the building.
We decided to divide the team into electronics (Marti and Alex) and mechanics (Gerard and Nikita) having Oriol in both subgroups as the bridge between the disciplines.
​
We need the material from the shopping list in order to start, but we can not wait so Gerard bought a sheet of plywood. Therefore we can start with the prototypes for the different parts of the machine.
We decided to start with the coin selector plates so we know how it works, it is crucial to know that the coins fall correctly.
​
29/04/2018
Today a big update since last one was done. As a team we have had a lot of work and research, trying the prototype and making concepts work. Also, as we moved on we had to change parameters and designs. This is not intended to be an excuse, we have been enough team members to be able to keep the website up to date but rather we decided to focus on the building. We apologize.
​
Then, our project is already in prototype stage and with the second list we will have the final build. Before that the implemention of the electronics components with the build prototype has to be made and meanwhile the mechanic team will do kinemathics simulation and final build with stronger materials and the definitive design dimensions.
​
The material will upgrade to polycarbonate instead of steel or aluminium since it shows the following advantatges:
-
High resistance to breakage
-
Transparency
-
Light
-
Optimal mechanical characteristics
-
High thermal resistance
-
High resistance to chemical and atmospheric agents
-
Dimensional stability
-
Electrical insulation
-
Can be shaped, glued and welded
-
Good planimetry
The design will be sent to be cut with a laser machine so we can have a good tolerance and that is crucial for the correct working of the machine.
​
As for the electronics of the project we have evolved quite a bit. First off we settled in what kind of power supply we will have to give power to the entire machine. We agreed on 12 V DC to be able to power stronger motors and 5V DC for the servo and logic boards. We accomplish this with a 220vAC/12vDC tranformer and a 12v to 5v DC/DC buck converter.
​
Speaking of motors, we will have one stepper (NEMA17), one servo and one DC motor.
The stepper will move the base were the servo sits and it will have the mission of select the position of the pushing guide.
The servo will move the rack and pinon system that will push the coin out.
The DC motor will rotate the entry and coin selectro parts at a constant level of 30 RPM.
​
A more extensive document was made explaining and argumenting the reason for each new component and their different needs.
​
​
​
PROTOTYPE EVOLUTION
1st PROTOTYPE
By the 11 of April of 2018 we had accomplished our first prototype. It was mechanically functional but all the electronics components were handled separated and yet to be mounted into the actual prototype of our SmartCash machine.
Thanks to this prototype we started to feel the dimensions of our machine, how it works and where it fails.
Main issues were regarding structure stability, the falling of the coins to the tray and the coin sorter layer.
Also, we could start to apply electronic components and test their strength in order to update the second shopping list in case it was needed.
The first prototype was mostly made out of wood and MDF wood, with the use of screw for the assembly.
