Weekly Update: Week 9

With the deadline quickly approaching we have reached our goals that we set in the beginning of the term. As you saw in the Memorial Day update, we had a working SD card shield. We were also able to make the valve on the new bladder connect to the tube from the CO2 canister. As you can see in the following video, that the whole system is integrated and working!



Since we have a SD card we started doing some tests with the device on our bodies. We conducted several tests including walking, jogging, sprinting, and then walking and sprinting on stairs. The following video captures one of the test. Along with the video is a line graph of the acceleration data recorded.




If you compare this data to the data from the graph on the last post (Memorial Day), you can see that there is only one line instead of three. The previous graph had three lines because it was recording the x-, y-, and z-axises. The new graph only has one line because the data from the accelerometer is going through a low-pass filter first.

Quick Update: Memorial Day Weekend

After a week of exams its nice to finally have a break. Luckily some of the things we ordered came, allowing us get some work done. In this quick update I'm just going to talk about the SD Card Shield.

We got the SD Card Shield a week ago but didn't really have time to implement it since we were trying to work on other problems. So this weekend, I sat down and tried to get it working. It was a success! At first it was a pain as usual. But after reading some online documentation (thanks Arduino community!), I was able to get things working. We're using a 64MB sd card to save the accelerometer data on. It might seem small for today's standards but for some plain text its more than enough. I was wondering how the data would look on a graph. With the sd card recording the data from the accelerometer I did some shaking, slow turning, and jumping. The following image shows what the data looked like. It'll be interesting what filtering will do to the graph. But that's for next time!

Oh yea the waterproof case came in! We're really excited to get our hands on it but since none of us are on campus, we'll have to wait till tomorrow.

Weekly Update: Week 8

The majority of the project is complete, and only the last 10% remain. By week nine we want the device within a water proof case for testing in water. In preparation for testing in water, we have been ordering components that we deem are important.

We ordered a SD card shield over the weekend, and I arrived this week. We will use the sd card to log data from the accelerometer when it is being dropped in the water to get a better understanding of what goes on when the device is in the water. From the data, we can also try to optimize when the bladder gets inflated.

Since our original bladder was not meant to keep a person afloat, we ordered a new inflatable bladder. The bladder came in on Monday, but there was some bad news. Not only was it a bit small but it also had 3 different valves for air intake. This would not be feasible. Therefore we ordered a new inflatable bladder. We ordered a new inflatable bladder, ones that are used during snorkeling. It's inexpensive and effective. It is pictured below:

Weekly Update: Week 7

     It's been a busy past week. We finally did a full system integration. Everything is now on one board and the Arduino is being powered by a 9V battery. The Arduino then regulates the power out to the accelerometer and servo motor.

     We are still having trouble making the valve close all the way. It doesn't seem to be the motor that is causing the problem, instead the piece connecting the valve to the motor has some freedom of movement. We did add washers and a nut to help decrease that movement. It only seems to close sometimes, meaning that it is not effective enough of a solution to close the CO2 canister all the way.

     In order to help solve the problem stated above, we decided to buy a larger inflatable bladder. We had planned on buying a larger bladder since the current bladder is not large enough for keeping someone afloat. The new bladder should be able to help bring a person to the surface of the water faster. It will also alleviate the problem with CO2 leaking from the canister. We are using a Y-valve to split the air from the CO2 canister into the two bladders.

     An item we bought recently is a SD card shield. This will allow us to log data from the accelerometer when we conduct tests in the water. We can use this data to further refine our algorithm to help detect free fall and impact more clearly and effectively.

Smart Suit Prototype Build v.2

We have a video of our first test! This is Smart Suit Build v.1

Weekly Update: Week 6

     With the end of our first set of exams and papers we were able to get a lot of work done over the past few days, including the weekend. We have successfully implemented the new mechanical design for turning the CO2 canister with the servo. We also solved the problem of the accelerometer wires disconnecting from the Arduino.

     The battery pack that we ordered last week arrived in the mail on Monday.

     This is the new design for turning the CO2 canister: There is a thin steel shaft that attaches around the CO2 deploy mechanism via a small clevis. This shaft is connected to the armature of the servo. When the servo moves, the CO2 is forced up by the steel shaft and CO2 is released. when the servo moves back to its initial position, the flow of CO2 is stopped and at this point the air bladder will be appropriately filled.

     To fix the disconnection problem with the accelerometer we decided the best way was to reconnect the ribbon cables. We separated the ribbon and stripped the rubber off the end. Then we connected new wires that are better fit to fit as pins. We connected the two wires by soldering them together. On top of that, we taped them tightly with electrical tape to isolate the bare parts of the wire.

     On Monday we continued to test the motor so we could figure out how to turn it to certain positions. We ran into problems trying to figure out where it started, more specifically what it defined as "0."After a long night we called it quits and worked on it on Tuesday. On Tuesday we were more successful. We found a way to successfully make the motor start at one position and then turn to the position we needed it to. The problem was that we misunderstood how the servo was understanding out code.

    Also on Monday, we successfully found a solution to stopping the entire program after the IBS had deployed. After some confusion on how to go about doing this, we simplified the solution to just putting a really long delay.

Weekly Update: Week 5

     We made some more progress over week 5. The pace of our progress did slow down due to some design problems. We got eventually worked though the design problems and are now set to move forward with implementing the designs.

     During the weekend we had designed a mechanical design that would help the motor turn the CO2 canister. We stopped by the Machine Shop on Wednesday to help implement the design. We had thought that using one piece of metal and bending it at the right angles, we would be able to wedge the top of the CO2 release valve between the metal. This would be attached to the motor that would then turn the CO2 canister. After going to the Machine Shop we ran into problems. If we bend the metal too much, the metal would break. This problem forces us to work on a mechanical redesign.

     The design for the electrical components did change a little since we decided to stick with the motor shield since we might add more shields or sensors in the future. We bought a 4 AA battery pack that should easily work with the motor shield and power the servo. The accelerometer continues to have some wire problems. The ribbons keep falling out so we are thinking up a solution for this but haven't thought of something easy and effective yet. But we plan to get the done next week.