@eshaanm

Today was pretty good because i worked on the CAD for the sliding adjustable rig. I spent most of the time on the stand for the main FMG band, and then put it in an assembly and tweaked a few alignment issues with the heights and sizes of the rests. Then i printed a portion of the rail and the rest so I can test the tolerances of the dovetail slide. those are printing right now but next I will probably print everything out and assemble the rig and also assembl;e the carriages on the fmg band. After all of this mechanical stuff all i have to do is polish the methodology and the code while i wait for the PCBs to arrive (they will take two weeks minimum so its going to be tight around the end).

it has been some time since my last devlog since school just started and all my PCBs and components are still shipping from china. I thought i would try to finish some of the other work while I wait in order to make it easy and quick once the baords get here. Today i wanted to work on the RIG that will hold the band aw sell as two adjustable rests for the arm. Ofcourse you can use the band without any of this but since this is a research experiment I want to remove as many variables as possible and keeping it in this way locked in one position does that and also makes it easier to test on peple and put it on. Most likelyfinal version will use IMU to correct for limb position and wont need this bulky rig but we will see. Im thinking of keeping the rig on a piece of wood and usinug a dovetail to slide around the FMg rest and arm rests. i modelled two versions. I still need to work on the FMG rest which has to be adjustable up and down but yeah i will try to get that built soon and also finish programming everything and the methodology so i am ready

I added the heat set inserts to the 3d print, soldered the headers on the teensy, ordered both the PCB and it’s components (will take 1 - 2 weeks), and 3d printed the carriage section of the captive leadscrew assembly

today I finished tweaking the PCB then I tried ordering the PCB and LCSC components. I was trying to do this thing where you combine orders to save on shipping, so I had to set the JLC PCB order address to the LCSC warehouse, and then I emailed LCSC and asked to combine my orders since I did not see the option on the LCSC checkout. I will hear back from them soon hopefully so then everything will come so I can star building. also I printed out the 3d printed parts and also got all my other supplied from amazon. I am a bit worried though because one jlcpcb order I cancelled and I do not see the refund on my HCB account

What i worked on today was I mainly was just uploading my reciepts for HCB then I had to go through the schematic and check all the circuits to make sure it was good for printing. I am glad I did because i found multiple mistakes with the SD card, IMU, and buck/boost. I then had to add some more resistors so i had to figure out how to reroute everything. i finished i think but it is still a mess so i can definately work on it for one more day before ordering.

today I got my grant approved which was awesome. I also updated my BOM to buy everything from amazon because it was easier than micro center for me. then I ordered the amazon and adafruit parts which is like 90% of everything. I was going to order PCB until I decided to check out my buck-boost circuit and realized it was completely wrong. so I fixed that. I think I will order the PCBs in a few days after double checking EVERYTHING.

so basicly what I have been doing for now is that I already sent out the project for funding review, but I thought while I wait I might make some small upgrades to the PCB. first I swapped out the through-hole pads for actual connectors (JST-SH?) which will make it much easier to connect the sensor boards. then I spent the rest of the time working on the PCB tracing I think I optimized it a lot more. next I have to double check all the PCB components and routing and then I have to prepare myself for my next steps when I get funding

Today I got some good feedback before submitting that I should polish my CAD and my README in order to get into the highest tier. SO first I worked on fully polishing the CAD with fillets, assembly, mounting holes, made it wider so its easier to slip on, fixed the carriages. and then I went to fixing the readme and GitHub where I added some pretty sick black and white images of the band. lastly I updated my BOM to reflect my budget. now everything fits pretty well under 250 dollars which is perfect. I am also now using JST-GH 1.25mm 3 pin connectors from the sensor PCB to the main PCB. I am retread to submit! I will keep working on small cad and PCB changes while waiting :D

ok today was just a good recap day and I think I can submit my project for funding now. what I did was first import all the CAD, PCB, BOM, PNG files into the GitHub and organize them. then I went through a whole thing with my BOM because I forgot to add a lot of stuff like wire and a battery. the total is now like 215 but I think it should be fine because I will just pay the extra myself. I also wrote a pretty long README.md which I am pretty proud of. I am going to submit this now so fingers crossed for the review. I hope it takes less than a week since I dont have time :(

Today was an ultimate lock in day. It says 3 hours, but I totally forgot about lapse for two hours before so in total I worked around 5 hours. My goals of course was to completely finish and submit project. I did not do that but I am definitely pretty close. Here is everything I did today. I switched back to the BMI270, I asked for help on my PCB from reddit, hack club slack, and on of my dad’s colleagues (meeting is tommorow), I moved to CAD where I made my walls thinner, fixed the holes for the PCB, added both PCB, the main frame, the screw, the dowels, the sensor PCB, and the nut carriage in an assembly view, I created a small carriage for the end of the screw so that the screw actually moves the PCB back and forth, then I moved to firmware and wrote a complete firmware that checks all the components (FSR, IMU, OLED, SD card) and has a loop which does the simple function for the board. Tommorow I just need to collect this all into a GitHub, do some last minute PCB/BOM checks and I can submit!

ok these lapses was from yesterday and the day before I forgot to log them but I got a lot done and also made one major change to the project. mainly I was finishing up the BOM again. I put if almost everything and it was fitting inside 200 dollars so I was excited. then I actually decided to check how much shipping and tariffs would cost and the total was over 150 just for the control pcbs. I realized in this budget automated assembly would not work so I decided I will assembly these by hand. most of the 603 components are super easy just the main issue Is that the IMU I am using has the pins under the chip which will be difficult for me to solder. anyways on LCSC I was able to get all the parts + lots of extra in case I mess up for under 30 dollars. Also I dont know if I covered this but Thursday I changed the IMU from he BMI270 to the LSM6DSVQTR which was very similar package, size, and pinout but also was economic for JLC PCBA. now that im thinking about it I can still use the BMI270 since I am assembling by hand. I might have to switch to BMI270 actually since it is a few dollars cheaper. so anyways for assembling by hand I have a hot air rework station already, so I have gotten a stencil from JLCPCB and also included solder paste, flux, and IPA on the BOM. I still need to kinda finish the BOM but for now it is good so I have to lock in and get everything ready to submit

ok today was a bit of a slowerish day ig. I started off with trying to fit all the pcbs into one board so It could be manufactured at once. but that didn’t work so well so I decided im going to print each separately. first I did the main control board. I am using JLC PCBA for this since I honestly can’t assemble this by hand… I mean, I COULD but it would be a risk and maybe same like 30 bucks. anyways next the 10 smaller PCBs were very simple so I am going to assemble by hand. I ordered the bare pcbs and am going to order the components separately on LCSC. supposedly once I order the stuff from JLC it will show up on my LCSC page and I will be able to combine the orders together so I dont have to pay extra shipping. we will see though.. anyways for the main control board it took forever because first the IMU couldn’t be made on an economic PCB so I had to completely replace that with some STM based one (which is actually more powerful and cheaper and economic). then I couldn’t figure out how to change my PCBA quantity from 5 to 2, after debugging for 30 minutes, I realized the issue was because of the COLOR OF THE BOARD. I had to change it to green and then everything worked ok. I attached the pictures of the cart and dang its not cheap. hopefully it fits under 200, I might try and get this on the highest tier though, idk if its fully that polished but we will see. next I have to lock in on firmware and also finish up a BOM with full cost + screws and 3d printing material. note that for LCSC cart im not paying for shipping so its more like 12 bucks. 12 (LCSC components) + 5 (10 PCBS) + 80 (JLC PCBA) + 2 (5 pcbs) + 20 (shipping + tariffs) + 25 (teensy) + 35 (FSRs) + 20 (screws + dowels?) = 199. prob more like 250 to be realistic so I might have to chip in myself..

What I did was finish the PCB from yesterday with all the routing. I was right and the last 30% of the routing was the hardest so I had to shuffle things around and also disrupt some of the ground plane on the back. I think in general this pub looks pretty neat. I definitely could have optimized it more but it should work perfectly fine I think. I think next I should start getting the project ready for funding. I need a BOM for that and a GitHub. I also should recheck the schematic and some of the layout or something because I can’t afford any mistakes on the board.

idk why I worked on this at midnight but I just wanted to finish up the layout. then I got carried away fixing the silkscreen. then I got carried on routing. my layout was on point because the routing was so easy and quick. id say im around 70% done routing but the remaining 30% are the toughest ones so we will see tommorow. im going to sleep.

today was a productive day, but I may have underestimated my previous goals. I basicly started as usual with a simple layout. I am def not that great at PCB layouts but I thought it looked OK, then I realized itwasnt very good for routing and once I started routing it was a mess. So then what I did was optimize the entire layout to make it super easy to route. at the end it was looking so fire and I thought this was the one so I started adding all the silkscreen stuff and logos and names. then I remembered that FSR signals are going to be analog and they need to be super precise. Turns out buck boost converters have crazy switching field which can mess with the FSR signals. My RC filters were also pretty away from the teensy pins. so I decided to fix that with V3. I first switched around the SD card and power management circuits so that the buck boost was as far away from mt FSRs as possible. then I moved up my RC filters (low pass). I think im pretty much finished the layout, there could be some minor neatness tweaks. there is also some dead space I need to fill. I do have to redo the silk screen though and route everything tommorow. so tommorow that’s the goal as well as maybe starting the BOM? (the pic in 3D is V4)

Today what I did was completed the schematic for the sensor board. the FSR uses an op-amp which linearizes the single as well as a VD and other caps to filter out the noise. I still want to learn more about op-amps since rn I copied the basic schematic from a paper I read. After that I finished routing the traces and creating the PCB for the sensor board which was pretty easy since it was so small. I also started the board size/layout for the main control board. Again, the goal is finishing the pcbs tommorow (I will have full day tommorow so it should be possible). Another day with good progress!

OK so basicly what I did today was finish the main sensor board. this is everything I added: a buck boost converter, RC (low-pass) circuits for FSR, decoupling capacitors, buttons and LEDs, debugging headers (I2C, Power, SPI, GPIO, UART), a voltage divider for battery, etc. So the next stuff to do is the sensor PCB that holds the FSR as well as a full BOM and GitHub. Good progress today!

SO what I have been working on so far right now is that I started the CAD and kind of finished the basic V2 for the rigid frame. I also started working on the PCB. SO far I have added the Teensy 4.0 microcontroller, IMU, micro-sd card, and the OLED. I still need the power circuitry, FSR boards, and prob other stuff I am probably forgetting. Goal is to finish the PCB in the next few days so I can start with a full BOM (I want to submit for review in a week)

Basicly what I have worked on so far is just making a CAD design for the band. I printed the first one off with PLA and it was looking good but pretty bulky. after that I designed a new band which was looking a lot more slimmer and lighter and stylish. the issue with that I am thinking though is that a rigid band is going to introduce so much issues for our study which is why im thinking of second guessing my design. also I started a littler bit with the pcb.

Today I worked on sketching out a few designs for the project and also the rough CAD and component selection so that I can start designing soon!