Author: sssahoo

This week we made significant progress as I integrated a fully-functional motor and slider with our 3D printed components to actuate braille. First, I worked with Ziyu to assemble a final version of the 3D-printed braille cells, pins, mount, laser-cut gear & rack, sliders, and both motors. Upon assembling, the motor code required a lot debugging as I tried to recalibrate the motors for enough torque, speed, and precision. We also verified much better performance after connecting the motor driver chips to 12V power source. I worked with Yujun to solve these last few issues. I also received the final JST-like 4-wire connectors that has significantly cleaned up our wiring as we transition to cleaning up for final demo.

My progress is behind for this week as I had hoped to finalize homing motor code by now. I will make up for this prior to the upcoming, and final, week. In addition to this, I hope to be able to manage all the braille cells we are able to produce in the next few days, such that we will be able to display multiple braille characters, sequentially, as desired for our MVP and use-case requirements.

This week, I worked on the motor code upon assembling a first version of our full build. Specifically, now that the laser-cut gear and rack is finalized, I was able to do proper load testing on the motor. I was aiming to meet our main design requirements, namely, speed, accuracy, and anti-jamming. I was able to get accurate positioning, except for times when one of the pins lagged behind due to printing imperfections. I also observed that my anti-stall code also worked to stop the motor upon detected a jam. I still need to work on homing after a jam since I faced some issues with the motor starting up again very slowly at first which would sometimes just raise another stall error. There were also issues with speed since I have not connected the motor driver to higher than Vcc 5V.

Progress is on schedule but there is much fine-tuning to do as we complete our final print. Next week, I plan to experiment with a higher power source to see if I can achieve improvements on speed while maintaining the torque I already achieved to properly actuate the slider.

This week, I continued to work on the Arduino code to process data and accordingly spin the motors a specific number of steps. First, Yujun and I worked to find a .txt file reader library for Arduino to import the encoding outputs from the Python translation program. However, I later found it was buggy as these libraries were not very sophisticated. So, I researched and updated our Python program, translation.py, with pyserial for serial communication directly with Arduino. I also built onto our Arduino code (stepper motor control and I/O) to also interface with the translation.py code. With this new mode of communication and processing, translation.py sends the binary encodings one cell at a time to the Arduino, which then processes the encodings, moves the two motors for a cell to actuate the pattern, and then sends a signal to translation.py when “next word” button is clicked. The reason for one cell at a time is that we are first finalizing functionality for only one cell before manufacturing and assembling the other nine cells for our final device. The code will meanwhile be updated to process and display one word at a time instead of one cell, as desired. My progress is now on schedule. For next week, I aim to:

– Move the serial communication between the web app Python programs and Arduino to wifi with our ESP32 board. Will work with Yujun on this step.

– I also aim to finalize fitting the motors and linear gear to our pending 3D printed housing parts. This step is crucial to then properly advance to manufacturing and assembling the physical hardware of the device.

This week, I continued to work on our stepper motors and all of the corresponding motor code. However upon testing with a load, the motor torque was not high enough, which I was anticipating from this testing. In order to achieve the load and precision of our sliding actuator, I decided to consider options for a reduction gearbox and a corresponding linear screw. I was able to find a few new parts that includes these modifications of this and thus purchased for delivery next week.

My progress is on schedule for this week, but since our order has not yet been placed last week, they will only arrive Wednesday/Thursday of this week, which might affect my progress of the following week. I hope to accelerate work once they arrive and have a final working setup of our entire motor subsystem. I will finish up Arduino code accordingly this week, upon receiving the final dimensions of 3D printed parts from Ziyu.

This week, I ordered, received, and began testing all the parts for our actuating subsystem. First, the ordering process was a little tricky since despite having finalized the motor model and type, there were various unknown vendors and distributors with wildly varying pricing and delivery times. As a result, this process took longer than expected. Upon receiving the parts, I have been able to get the micro stepper motors to function and control using Arduino and the motor driver. I still need to program the precise positions along the linear output. My progress is still a little behind, but compared to the previous week’s state, I have been able to make significant process this week.

I also decided to significantly adjust our team’s schedule since the whole team has been behind schedule. The consequence in that the upcoming two weeks now requires parallel progress on various subsystems + testing.

At the end of this week, I hope to have a fully working motor and sliding mechanism, ready to attach to our 3D printed actuating components. Additionally, if this is accomplished, I will assemble all motors and drivers. However, I need to purchase a different motor driver IC in order to properly support our software-controlled motor control for actuating.