Author: rbutton

What’s new?

• PCB did work, had a power issues 🙁 Could just be a one off mistake, but didn’t want to waste time debugging  because we were having more fundamental control issues with A4988s
• A4988 motor controller were cumbesome, had issues going both directions, switched to l298N, easy to control, resolved issues at the cost of 4 pins on arduino as opposed to 2.
• transitioned to a module based circuit design scheme, which has made it easy to get hardware up and running, and also help isolate power features of design, as well as trouuble shoot circuitry because we can isolate what we know works from what doesn’t. This circuit format is less robust than a PCB but better for its ability too iterate quickly.
• Finalized Fundamental mechanical design for the most part
• Got feedback on where to place registration tool from LAMP feedback session.
• Decided to transition from using 4 solenoids to using 2 solenoids due to a combination of lack of IO/pins depending on how sensors are configured, and unexepected jiggling of solenoid stylus which loosens screw over time. Think this issue can be mitigated with lock tight
• Learned about detent current, which can cause stepper motor to torque despite coils not being energized. Was worried we would have to get a new stepper which wouldn’t arrive until Friday. on a whim designed to power each coil to try to untorque motor, and it worked!
• Made a test version of ir sensor
• think we need to transition to LDR

What next?

• Finalize and get light sensor working
• tune vertical height on solenoids
• mount braille directives
• learn why detent current gets triggered sometimes

ABET #6 says … An ability to develop and conduct appropriate experimentation, analyze and interpret data, and use engineering judgment to draw conclusions

Now that you are entering into the verification and validation phase of your project, provide a comprehensive update on what tests you have run or are planning to run.  In particular, how will you analyze the anticipated measured results to verify your contribution to the project meets the engineering design requirements or the use case requirements? 

I’ve worked on the X/Y gantry system and the circuit design components of the project. The relevant requirements for me have to do with tolerances printing the braille and speed.

Mechanical Precision & Functionality: I will test to ensure that the placement of the gantry system allows for embossing, that the x gantry isn’t too close to the compliant surface. I need to test various compliant surfaces and select the best one. So far I have tested felt, styrofoam, and 1 grade of low density foam.

Usability: I need to test that our user can be able to determine which side the paper goes in quickly. I have created a texture that will be tested at this week’s LAMP demo, and we will get feedback there on its effectiveness.

PCB Testing: The PCB is set to arrive next week, and we will need to verify that it does all of the things we think it will do.

IR Sensor Placement: IR sensors are susceptible to reflective surfaces, so we need to do testing to see what position will not get bad signals from  reflecting off of the acrylic. This is important to our requirement tests because the IR sensor actually verifies that the paper has been placed in correctly.

Weekly Update:

I redesigned the PCB to be Arduino compatible given our team’s recent decision to switch the hardware over to be controlled by an Arduino, and communicate over UART to talk to the Raspberry Pi. The PCBs will be arriving just before Thanksgiving, so we will be able to test them during the break.

I ran into issues with the stepper motor circuit this week during demo. The current limiter circuit appeared to be not functional, and I did not have the tools I needed to do further testing during the demo.

Next week, I plan to build the Y axis component. I reached out to Zach from Ideate, and he will be bringing be a broken printer to take apart and get the rollers out of.

This week I met with a mentor to discuss the loading system for the embosser, so we can finally order parts. I testing a few compliant surfaces and found that felt mounted on styrofoam would be  a great surface to print on.

I made some modifications to the loading system which include sensors to help determine where the paper is on the y gantry system, and side panels to ensure the paper is registered correctly.

I also realized that controlling all of this hardware with the raspberry pi may not be the best idea, because a lot of hardware controls tend to act pretty fast, and theyre may be latency introduced by having software and hardware processes done all on one unit

ABET #7 says: An ability to acquire and apply new knowledge as needed, using appropriate learning strategies

As you’ve now established a set of sub-systems necessary to implement your project, what new tools are you looking into learning so you are able to accomplish your planned tasks?

I am using Eagle CAD to design the PCB’s for the final project, and Fusion 360 to CAD the mechanical components of our project.

What did you personally accomplish this week on the project? Give files or
photos that demonstrate your progress. Prove to the reader that you put sufficient effort into the project over the course of the week (12+ hours).

This week I worked on the design report, and I finished up ordering parts for the X gantry, and started designing the PCB for the project. There was a lot of stuff I needed to import so I had to make sure they lined up to the A4988 stepper drivers we already purchased. Since EAGLE didn’t have the parts, I had to carefully source libraries.

Here is the schematic, the PCB will be routed next week.

Progress and Deliverables

This week I didn’t get as much done because we were on break 🙂 I plan on getting the PCB sent out on Tuesday to Flash PCB, and they are willing to manufacture our stuff faster, so we should hopefully have it back in a week.

This week I plan to send out the PCB to get manufactured, and get started making the X/gantry system. I want to tweak the y gantry this week, but that probably wont happen until this weekend.