Конец: The Final Blog Post

For our final project, we wanted to work with the Child Study Center. One of the problems they had was the issue of the kids (2-5 year olds) being unable to reach the top shelf of their cubby. The average 5 year old is about 3 feet tall, whereas the entire cubby is about 5 feet tall. When they wanted to reach something in the top shelf many of the kids stepped onto the middle shelf – not very safe. We came up with the idea of creating a stool that could easily slide in and out – we ended up using drawer slides to accomplish this. There also needed to be some form of a feedback and control system built into place as a way to remind the kids that they needed to push the cubby buddy back in. In our case we eventually decided on using a button as the sensor, while could then prompt a reaction in LEDs. The LEDs would be placed across the top of the cubby and under a sign in the back of the cubby that reminds the kids what they need to do.

Measurements and original concept design

WEEK 1 & 2:
We spent most of week one and week two brainstorming about how this cubby would work and what sort of materials we would need to create. We also scheduled a visit to the CSC to take some measurements and observe the kids at their cubbies. After presenting our idea to Becky she encourage us to make our project 'kickable,' as children are a little more top heavy, being able to kick the Cubby Buddy back into place is actually safer.

 WEEK 3:
We spent week three creating a cardboard prototype of our cubby/Cubby Buddy. Taking the measurements we took at the CSC, we were able to create SolidWorks parts that replicated what we wanted. After lining everything up properly, we were able to determine how much wood we would actually need for our project. We did some more brainstorming and came up with a final list of the things we would need to buy and submitted those to Amy. In addition, we typed up a Arduino code that would give us our desired blinking affect and put together a working circuit. (For a video of the working code, please scroll down to the end of the blog post.) We also took this week as an opportunity to practice our soldering skills.

WEEK 4:
Our wood arrived this week, so we were able to begin assembling the real thing. Unfortunately when Home Depot cut our wood into three pieces for us, they cut out the wrong sizes. We had to take a bit of time to recalculate our desired dimensions before we were able to begin cutting. Once we had the correct measurements, we went over to the machine shop to begin sawing. Special thanks to Larry who taught us how to use a table saw!

Once we had our pieces cut out we were able to begin the assembly process. We started with attaching the drawer slides. This was the hardest part of the project. Once we had the drawer slides screwed in, not an entirely painless process, we were easily able to attach the rest of the boards together. The only bump we ran into was that we had attached the top of the cubby buddy on first without attaching the L brackets (sturdiness and extra safety). We forgot to take into consideration that the drill would not be able to get into where the screw needed to be drilled in. We had to unscrew the top to get the L brackets in which was a bit of a back track. This was a good lesson in thinking ahead a bit more during the assembly process.

WEEK 5:
Our next step was creating the sensor and feedback portion of the project. We soldered two long wires onto the legs of the button and placed in the back of the cubby facing the cubby buddy. When the cubby buddy is pushed in, the button will be pushed and nothing should happen. If the cubby buddy is out, the button will no longer be pushed and should cause the LEDs to start blinking.

After putting the button in place, we then had to drill in holes for the wires to run through so they could connect to the top of the cubby, where we wanted to place to the Arduino. This was another example of things we should've thought out a little bit more. We didn't think about the wires when we were originally putting together our cubby, which made things a little bit more annoying. The drill didn't really fit into the corner where we wanted to place the hole so it took us some maneuvering to drill the hole. If we had thought of this earlier and drilled in the holes pre-assembly it would have made things a lot easier.

For the LEDs, we wanted to have two series of blinking lights. One would be a strand of lights that ran across the top of the cubby. The second would light up a sign that reminds that the need to kick the cubby buddy back into place. Vivian was able to create the string of LEDs by soldering LEDs in parallel onto a pair of wires. We glued the sign & a string of LEDs to the back of the middle shelf and taped one of the strings of LEDs across the top. We ran the appropriate wires to our bread board and double checked to see that everything work.

Once, we had all our components in desired place with everything working, we then began to solder the wires onto a permanent circuit board. This was relatively painless, although some of the legs of the wires kept snapping off. Once we had our wires all soldered together. We decided to fashion a wooden box to place the Arduino and circuit in. This would make the product a little more aesthetically pleasing and hopefully less exciting to the kids, so they won't be tempted to play with it. We made a little cover for the craziest part which was the where all the wires connected on the circuit itself. As a final touch, we covered the wires that ran along the corner of the cubby with black electrical tape.

For addition support, we also needed to creat feet on the front of the cubby. Since the CSC cubbies are built such that there is a bottom to the cubby, the cubby button does not touch the floor when pulled out. When weight is placed on top of the cubby buddy, the weight is being solely held up by the drawer slides, causing them to bend. This is not very safe and safety is a priority with this project. We created a U shaped piece of wood and attached a sheet of Delrin plastic onto the bottom because the flooring at the CSC is carpet. The plastic made it so that the Cubby Buddy will be able to easily slide in and out.

As a final, final touch to our project we sanded down all the sides of the Cubby/Cubby Buddy because we wanted to make sure that our product would be safe for any kid or adult that came into contact with it.

Our final product:

Reflections:
One of the major flaws in our product is the placement of the drawer slides. Instead of placing them towards the bottom of the cubby buddy, we should instead place them towards the top. This should create a more stable final product. Further, for the sake of aesthetics, I would want to see if could find some way to make the wires less visible – in particular, the LEDs that went across the front of the cubby. In the similar vein of thought, I would have loved for the opportunity to paint the cubby/Cubby Buddy, but given the time and monetary restraints, this was a possibility for this project.

In addition, when building the cubby/Cubby Buddy, we ran into a few obstacles when we failed to completely think through the order we needed to assemble the parts. This is only natural as this is our first version and we were still brainstorming throughout the assembly process, however, we would want to avoid this during further versions.

The total cost of our cubby buddy came to about $34. This isn't terribly expensive, but when the CSC has 37 cubbies, the price does appear a little steep. If we were given more time and did a little more research, we should be able to easily bring down this cost to something a little more affordable.

Overall, I think our final product is a really good representation of what we had in mind when we wanted to design a product that could help the kids at the CSC. I'm pretty happy with what my group was able to create in the last few weeks of the semester. This simple and easy-to-use product, given more iterations, can become a very safe and viable option for kids.

Video of basic working code:

Video of working product:

Final Project Week 5

We spent this week making any edits that were brought up during the pilot at the CSC. Things we needed to fix/add included:

• putting the pushbutton into position & connecting the pushbutton to the circuit board
• stringing together LEDs & connecting them to the circuit board
•  adding a piece of wood+delrin to the the front of the cubby buddy that reaches the floor to improve stability
• removing the gap in between the cubby buddy and the back of the cubby
• soldering wires together and find a way to cover them
• sanding down the edges

Vivian figured out how to create strings of LEDs in parallel which Rachel and I worked on the finishing touches on the cubby. In order to light up so many LEDs via one output, we found that they had to be created in parallel. Vivian made small cuts into cut out lengths of wire and soldered on each individual leg of the LEDs. In no time, we had two strings of LEDs! Who needs to buy christmas lights when you can make your own!

While Vivian was making the LED strings, Rachel cut out a u-shaped piece, that attaches to the cubby buddy for support, and glued on a piece of Delrin, that will make sliding the cubby buddy over carpet easier. Next we needed to put the button into position at the back of the cubby. After deciding which side we wanted to place the button, we soldered wires onto the legs of the button. We cut out a grooved piece of wood to hide the wires behind and two small pieces of wood that were to be placed above and below the button. On the side without the button, we added a longer piece of wood to remove the gap between the cubby buddy and the cubby.

Since we put together a lot of the cubby and cubby buddy before having thought through all the additional features, we weren't able to drill in screws from the front and had to drill in a lot of holes from the back of the cubby. If we were to create a cubby buddy 2.0, given our experiences, we would definitely rethink the order in which we attached things. In our above scenario, it might be better if we had attached the button to the back of the cubby before attaching the back of the cubby to its sides.

Either way, we now have a working cubby buddy!

While testing the cubby buddy, we found that the button wasn't fully pressed unless the cubby was firmly pushed back into place. To fix this, we added a thin piece of scrap wood to the back of the button, so that it would be propped forward. This helped to make the button more sensitive and properly turn off the LEDs when the cubby buddy was pushed back.

We also soldered our wires onto a smaller circuit board to make the electrical connections more permanent. To hide the mess of wires that is on top of the cubby, we decided to fashion a small box to fit all the components.

We also created a small cover to hide the circuit board, so that it would look more pleasing to the eye. We decided not to cover the whole box so that it would be easy for adults to change the batteries if needed, or to unplug the Arduino. If we had more time and a slightly bigger budget, we might consider attaching a top, that covers the whole top, with hinges or via some sort of sliding mechanism.

We then used some electrical tape to cover the wires that extend from the button and the LEDs to the circuit board/Arduino. These final touches gave us a more pleasing overall aesthetic.

I'm very pleased with how our cubby buddy turned out. Our final product is a really good representation/improvement on what I had in mind when we started 4 weeks prior. If given the opportunity to remake our cubby buddy, there would definitely be changes to our design, i.e. placement of the drawer slides and changes to the construction of the cubby/cubby buddy, i.e. order in which we attach pieces. But as a first rendition, I am very pleased with how everything turned out!

In sports related news, the Chicago MLB teams are leading their respective packs, the White Soxs are leading the American League with a 18-8 record and the Cubs are leading the National League with a 18-6 record. The Giants aren't looking so hot with a 14-13 record, but it is still too early in the season to say anything definitively!

Final Project Week 4

This week, we got our wood and were able to begin building our cubby! Unfortunately, as real life never turns out exactly as planned, we had to make a few changes immediately. The first thing we had to confront was the fact that the widths of the sheets of plywood were cut incorrectly. This meant that we had to scale down our design to reflect the change. In addition, as is the nature of wood, a few of our boards were slightly warped and did not lay completely flat.

Here are diagrams of our new desired dimension:

After we calculated our new dimensions, we sought out Larry's. He showed us how to safely use a table saw to cut our planks into the desired sizes. Safety rules we needed to keep in mind included turning the machine off after every cut, keeping other materials off the table when cutting, and making sure to drive the plank all the way past the blade when cutting. If you don't run the plank all the way past the end of the blade, you risk having the blade shoot the plank back at you. According to Larry the force of the table blade's saw is strong enough to fling a piece of wood into a concrete wall – so we really want to avoid that. The table saw is a very useful machine, but it is also a very dangerous piece of equipment, so we need to exercise extreme caution when using it. It is also important to note that safety glasses should always be worn and hair should be tied up.

Once, we had our pieces, we were then able to start assembling. Also huge shout out to Larry for letting us borrow his drill and drill bit! Pilot day with Becky was approaching quickly, so we had to work efficiently. The first thing we tackled was the attachment of the drawer slides. This was the hardest part of the assembly, but it also had to be one of the first things we did... We decided to attach the drawer slides toward the bottom sides of the cubby buddy because in our experiences, we've conventionally seen them placed toward the bottom of drawers. After some advice during the pilot day, we realize that we might be wrong with this decision...

The drawer slides were very difficult to put in because they needed to be attached to both the side of the cubby buddy and the side of the cubby – there wasn't a lot of space for error. Due to the amateur nature of the installation and the fact that we used dry wall screws with slotted heads (they're harder to drill in), we ended up stripping a screw or two... oops. Surprisingly we didn't split any planks during this process. This cannot be said for the rest of the assembly process.

Once, we attached the drawer slides, the rest of the assembly process felt like a breeze, although we were plagued with a few split planks every once in a while. To avoid this as much as possible, we set the drill to the lowest setting. When the screw was drilled in slanted however, the splitting was inevitable. Our solution to split planks was using some wood glue to make the splits less apparent and drilling another hole further down the plank.

For the most part the assembly didn't include any further setbacks, although we screwed on the top of the buddy before screwing in the supports. This wouldn't be a problem except for the fact that the drill didn't fit into the space between the planks, so we needed to remove the top of the buddy before we could attach the supports. Oops. This was a relatively minor setback.

By pilot day, Friday, we had our cubby buddy assembled sans the arduino portion and a few minor details. The presentations took place in the Child Study Center, so we needed to bring everything over to the CSC. This was quite the arm workout, but the cubby buddy make it over to the CSC safely and in one piece!

At the CSC, we were able to see the progress of everyone else's projects. This was really neat seeing the evolution from abstract concepts to physical prototypes. I'm very excited to see the final products!

During our meeting with Becky, we presented our project and discussed some of our and Becky's concerns. One thing we noticed was that when we pulled out the cubby buddy, since our cubby buddy is built on top of the floor of the cubby, the buddy would be 11/16ths of an inch above the ground. This instability was concerning and after some discussion we decided that adding a piece that poked out a little bit, about 1 inch, wouldn't be too much of a problem. Professor Banzaert also brought up the point that the flooring in the CSC is carpeted, something we forgot to take into consideration. She suggested that we attach a piece of delrin to the bottom of the added plank that would make sliding the buddy in and out less difficult.

As a mentioned earlier, also regarding the stability of the cubby buddy was the decision to place the drawer slides toward the bottom of the drawer. Amy Q brought up the fact that this was true, but in general drawers are built opposite the way ours is. Our design can be viewed as an upside down drawer, therefore we should've placed the slides towards the top. Unfortunately, as I mentioned a few paragraphs ago, the amateur installation of the drawer slides meant we stripped some of the nail heads... However, since we did add in right angle supports underneath the cubby buddy and our goal is supporting a 50 lb child, it shouldn't be too much of a problem. If we were to create a second cubby buddy/ cubby, this is a change we would definitely make.

We also decided to change the placement of the button from the side of the cubby to the back of the cubby. If we were to place the button on the side of the cubby, the button would be clipped every time the cubby buddy was pushed back in making it more likely to be broken. By placing it in the back, there wouldn't be a clipping effect. We also decided to add some planks to the back of the drawer because our cubby buddy doesn't extend completely to the back of the cubby and there was some concern that space towards the back could lead to the possibility of wedged items which would prevented it from being pushed back in completely.

 We also decided to add a few minor details that included placing the arduino on the top of the cubby so the children wouldn't be tempted to play with it. We would need to drill in a few holes so that the wires would extend down to where the lights would be placed and to the very bottom where the push button would be. Speaking of the lights, we decided to keep our original idea of including lights on the edge of the cubby. This would make it so that it would be more apparent that the cubby buddy wasn't pushed all the way even if big puffy winter jackets make it hard to see the sign during the colder winter months.

All in all I don't think we're in a terrible place. We have to make a few simple edits to our design and work on some soldering and the placement of our pushbuttons and LEDs. It's not going to be a cake walk, but it seems very manageable!

Final Project Week 3

We spent this past week creating a cardboard prototype of our final product and doing some research to figure out what sort of materials we needed to buy.

After doing a bit of math, mental deconstruction, and the help of Solid Works, we were able to calculate the amount of plywood that we would need for our project. We had to first decide how each piece would fit into another – does this piece go on top or does this other piece. Once we figured out all the details, we were able to conclude that one sheet of 4ft x 8ft would be enough. This is great because one sheet costs about $26.50 and we didn't want to blow our whole budget on wood. There is a very small margin of error when it comes to our wood usage, so hopefully, once
we get our hands on the plywood, the cutting will go smoothly! *knocks on wood to be safe*

In addition to the wood, we needed to buy some drawer rails. In our previous posts, we talked about how we were planning to use wheels, but after consulting Amy, she told us that drawer slides would be much easier to use. We managed to find some on Amazon that were relatively cheap – around $9 for a pair.

We also added some support pieces after consulting with Larry. After a brief discussion about our plan, Larry suggested that for added support, we should add some L brackets to the underside of our design. We thought that this was great advice and was able to find some for about $2 a piece.

When we brought up the idea of a handle to Amy, she shared with us the idea of having a hole instead of a handle. By creating a hand hole (where we've labeled handle), the children can easily open the cubby without the fear of running into them on a daily basis. Plus this lowers the initial estimated cost of our cubby.

Our initial plan includes having hand holds on the cubby for the kids to grab onto for balance when they step onto the cubby buddy. Becky was very excited about our idea, however, we are having second thoughts about having handles for fear that the kids might run into them. We are planning to include some handles in our prototype, but will definitely bring up our concerns with Becky during our Pilot Day.

We also managed to write up a working Arduino code for the
flashing LEDs. When the button is pressed, the drawer is pushed in, the LEDs should be off. When the button is unpressed, the drawer is not pushed in, the LEDs should be blinking.

It is a fairly simple code, but since we haven't worked with Arduino in a few weeks, it took a little bit of a refresher to remember how the wires lined up. With the help of our old blog posts, we were able to figure out the connections with no problem.

Here's a video of our blinking LED code:

Since we're using an Arduino board for our project, we needed to learn how to solder our wires and board together. Vivian, Rachel, and I already have a little experience with soldering from Physics 108, but we thought a refresher would be very helpful.

Soldering is the process of creating an electrical connection between two electronic parts. Using a soldering iron to heat up the pieces to be connected, we then bring a piece of conductive wire near the pieces. This wire will than melt and connect our two parts. As the melted piece of wire contains lead, it is better to err on the side of caution and avoid breathing in any fumes.


After Amy's demo of the soldering process, we were able to put together a small either robot or spaceship with blinking lights. I chose the robot!

All-in-all, I feel that our group is in a good place. The biggest challenge will definitely be getting the boards cut and assembled in time for Friday's pilot day.

Thermal Systems Part 2

For the second half of our thermal systems work in MATLAB, we got to test out our coffee simulation in real life with simple 50 ohm heater, a thermal reservoir, and a temperature sensor. After some initial setup of the MATLAB program, we are ready to begin.

Deliverable 1:

For the first deliverable, we were given a code to run and examine. By examining the graph the program produced of the rise in temperature of the heater and using a few equations we've learned about and used in part one, we were able to solve for the Rth(resistance) and C(capacitance) that would allow us to simulate a similar scenario. 

By estimating the initial slope and using our handy dandy equations, we found values of 6.9 and 16.2 for Rth and C repectively. Given the equation to the right, we calculated a theoretical time constant of 112.1 s. At time 112.1 s, the temperature of the system was 338.6. K

The time constant is defined as the time the system takes to reach 63.2% of it's final value. So, in order to calculate the actual constant, we found the total temperature change and calculated 63.2% of that. Added that number to the original temperature of the system and we calculated a temperature of 333.4 K. This tells us that our theoretical time constant is a little bit larger than the actual time constant.

Deliverable 2:

When we recreated our simulation of the heating coffee and compared it to the more realistic scenario with the heater, we founded that both graphs were very similar. The graph from deliverable 1 is scaled a little differently, but when you zoom in closer it has a very similar curve to the one we find in deliverable 2. The most apparent difference is that the room temperature from our simulation does not match up with the actual initial temperature of the heater. We also found that while our simulated version gets a temperature of ~335, in our deliverable 1, we only managed to raise our temperature to ~327 K.

Deliverable 3:

Here's a close up of the section of temperature values at the plateau

as we can see from the right side of the graph the bang bang is being implemented

Our simulated bang bang graph

Deliverable 4:

When the proportional gain is small, the system is unable to reach the control set point because it is increasing temperature at a such a small rate, the it reaches an asymptotic state long before the temperature can reach the goal of 340K. When the proportional gain is larger, the temperature rises very quickly in the beginning and plateaus. This suggests to us that the optimal gain is a Kp value around 0.2 in which the temperature more gradually reaches the goal of 340K.

Kp = 0.5 – reaches 340K really quickly

Kp = 0.2 – gradually reaches 340K

Kp = 0.05 – never reaches 340K

Overall, we found that working with circuits on the MATLAB was pretty neat, but it was not without it's challenges. In comparison to the simulations, the actual heating took a lot more time to produce really similar results. Unlike in the simulations, every time we ran the program we had to wait for the heater to run for the time determined AND the time necessary for the mechanism to cool down. This was especially frustrating when in the midst of debugging. But, all in all, this was an interesting exercise in coding and the various methods of heating an object (bang bang v. proportional).