Category: Theo’s Status Reports

I’ve taken the past week off for Spring Break since I’m on schedule. The week before, we received the parts for the manipulator’s structure, so I actually built it (see image below). The parts all fit together besides the 3D printed mount, which needs slightly larger holes for the stepper motor to fit inside. We’ll 3D print this when we return to campus. So far, we’ve noticed slight instability and rough motion when trying to move the 3D printed mount up and down the screws with spacers. If the next iteration’s larger holes don’t enable the smooth and stable motion we want, then we’ll look into linear bearings or something similar.

We’ve also further theorized possible solutions to picking the object up during rotation. Currently, solenoids on the mount that push off of the second layer of T-channel extrusions is our best idea. This would likely work, and we would use at least two in order to deliver equal/symmetric force while sliding up the screws.

My next steps include finishing the troubleshooting on this 3D print, helping Sophia with integrating my basic serial test code with her control software, and designing + optimizing the 3D printed shaft-suction cup piece that we’ll use to connect the vacuum pump tubes and the stepper motor to the suction cup.

This week, I practiced more for my presentation before presenting on Wednesday and spent time figuring out the suction cup’s connection to the stepper motor. I found a shaft coupler that doubles as a mounting platform, to which I’ll attach a 3D printed mount for the suction cup that allows it to be rotated by the stepper motor while connected to the air pump. I ordered this, along with some more air tubing connectors and 3mm mounting screws (our stepper motor didn’t come with any), in our second amazon order. Our first amazon order and our adafruit order came in later this week, and I picked them up along with the 3D printed circuits mount (see electronics in github). The holes on the mount needed the slightest bit more clearance, so I added 0.25mm to the radius of each hole. We’ll 3D print it this weekend or next week.

On Saturday, I started prototyping with the electronics that had come in from Adafruit and was able to control the stepper motor and air pump over serial. I’ve attached a picture of the setup below. Now I’ll wait for our new 3D printed mount, the suction cup, and the rest of the structure/hardware to come in before building a complete prototype.

This past week I prioritized finishing the manipulator design and ordering the parts. I also finished the CAD mockup, including the first prototype of a 3D printed mount for the electronics. It will freely move vertically on top of the manipulator to account for objects of different heights/thicknesses. I’ll 3D print this mount and test it once the ordered parts have arrived and the rest of the manipulator is put together.

Though I’m still behind on my tasks from the roadmap, a lot of future time was allocated to debugging the hardware, characterizing the working prototype, and designing a new version with a suction cup manipulator (instead of just a friction tip); this time may as well be slack time that’s instead used for this prototype. We’ve gone ahead and ordered the air pump, tubing, and suction cup with the rest of our parts. The suction cup is the same material and size (silicone for high coeff. of friction, 13mm diameter to fit behind a dime or similar coin) as we would’ve made the friction tip, so we will simply test the prototype with and without activating suction instead of needing to build an entirely new prototype/add-on. I believe this will be a massive time save, and don’t foresee any issues with the current design. I’ve uploaded the solidworks assembly+relevant files to github.

Besides working on the design and prototype, I’ve worked with my team on the design review presentation slides. I’ll be presenting on either Monday or Wednesday, and the tentative plan is to finish a draft early enough tonight or tomorrow so that our TA can look it over and give advice.

My work this past week consisted of helping with the proposal presentation and drafting a prototype + its CAD model. I was responsible for the hardware requirements, specifications, and solutions in the proposal, and helped with edits to the entire presentation in the time leading up to presentation day.

The CAD model is a few days behind schedule according to the roadmap. This is mainly due to me wanting to render the functioning linear actuator/lead screw, rotation motor, and microcontroller. I am still working on this model and have additional free time this week to catch up. The current prototype will be built out of 1-inch T-slot aluminum extrusions (CADing done with parts from 80/20), using an ESP32 dev board capable of operating a motor driver and at least one stepper or servo motor. I am still weighing the pros and cons of a linear actuator vs a manual lead screw, as well as a stepper motor vs a servo motor. The circuit will likely need an external power supply to power any of these motors, since the traces on an ESP32 won’t handle the power necessary to keep the motor powered over an extended period. This should all be resolved and the parts can be ordered by the end of next week. Though this places the hardware behind schedule, I am not worried. Assembly will be simple and can be done the day the parts arrive, and all should be back on track after that; the characterization task that comes after assembly should really only take a day or two, and the programming itself will be simple motor control. There is plenty of slack time in these first few hardware tasks that allow for this setback.

I’ve started on a basic arduino program for controlling the ESP32 and testing the stepper motor system’s accuracy. One of the first things we’ll be testing once we have the ESP32 is our ability to send it commands from our project’s software. If the arduino IDE/language doesn’t work, MicroPython is the next most likely route of hardware programming.