Through UW's BME Design Course, I've had the opportunity to design a prosthetic ankle for someone with a trans-tibial amputation. Our client's ultimate goal is to break weightlifting paralympic records. Our design team came up with a one DOF ankle that biomimetically assists him with a squatting exercise through semi-active torque modulation.
The graphs show inconsistencies in ankle moment throught the squat movement. His prosthesis is on his right ankle. Using our prototype, our client is able to keep his balance. The blue and red lines should converge after he has trained with it for the summer. This would indicate whole body force generation symmetry.
This semester, we've added dynamical control of force return using sensors, actuators, and a microcontroller. The entire device is controlled via bluetooth app on our client's smartphone.
We are in process of patenting this idea with WARF. If you are interested in partnering, please contact me to explore opportunities.
No, it's not as dark as it sounds (please help me find a better name for the sake of my elevator talks). This device is used to test below knee, or "transtibial", prostheses. These are beneficial because recruiting subjects for intermediate trials or troubleshooting can be a major setback in terms of development time.
Currently, researchers are attaching prostheses to the underside of an aircast boot. This setup requires a lift shoe on the contralateral side and a brave subject. Additionally, the gait of the subject is irregular due to an extended shank and foot. The device I'm proposing will retain the rotational component of the knee and control for mass of the researchers shank by spring. Since the anthropometry more closely matches the ideal, a lift shoe isn't needed.
Autonomous devices rely on control schemes that ensure a smooth transition from one state to another. In this project, I'm looking to design a flight controller that demonstrates the properties of PID control. As an added challenge, I've used the cheapest components possible.
The copter relies on an Arduino Nano for processing and an NRF24L01 for communication. The control originates in a 12 camera motion captures system and the application of PID gain is calculated in MatLab. The motivation here is for teaching control in UW's "ME 439: Introduction to Robotics", where students can implement their own controllers. A Github repo with code and 3d models will be available soon.
This version is finally the real deal, with a custom circuitboard for the central components, headers, bullet connectors, balance, it is in the air. After a month of "the PID just needs a few more hours of tuning" it sustains flight. Next, I plan to use a sort of optimization framework to cut the angular error under 1 degree and integrate VTOL.
A nice addition to this craft is the custom PCB which replaces the protoboard. This allows me to switch arduino boards if necessary. This was my trial by fire using Altium, but turned out great! 10 boards expedited for $20 isn't bad. The 450mm frame included power distribution which was a bonus. Hopefully this one can take a beating.
Version 2 was the first time the craft looked elegant. The first frame I put together in about 10 minutes with acrylic scraps, a balance nightmare. This frame, weighing under 1 Kg is lighter than what I'm currently working with, but much more fragile.
Unfortunately this one hit the pavement without any grace after a serial buffer overflow issue. Most of the craft was salvageable, but the bottom joint required heavy taping, I ultimately abandoned this for a consumer frame. Also, while experimenting with voltage compensation, I blew the Arduino. This experience is a perfect example of "learning the hard way". Trying to find the fast way, rather than the right way to develop, may not turn out that well.
There's nothing like waking up to the morning sun and a fresh cup of coffee. With my home automation system, I can do just that. Based on my sleeping activity, the blinds open and a fresh cup of cold brew (the best temperature of coffee) is poured when I'm ready to start my day.
The backbone of the system is Openhab running on a Raspberry Pi 3. Each subsystem runs on a NodeMCU development board which communicates with the RasPi through an MQTT broker. Most of these systems are on the backburner due to my heavy courseload, but come spring, we'll be up and running. The following are planned features:
This board sits in the corner of my bedroom near the floor vent. This is reflected in the volatile plots to the left. The Node broadcasts the temperature and relative humidity at .5Hz to the Raspberry Pi via MQTT on WiFi and then recorded in a SQL database. From there, my interface plots the timeseries. I've already learned that the magnitudes stabalize when my door is open. This node also operates a motor controller via GPIO to turn on the ambient lighting and open the blinds.
The Raspberry Pi is cozied up next to the router for an ethernet connection (WiFi works as well). Another node sits on the counter and reads the moisture sensor. My mother says to water it once a week; that turns out to be everytime it hits '700'. I think this was a second generational offshoot from my grandmothers plant, so does that make it my brother?
The following are projects I have worked on in design, projects, curriculum development, or hobby. I'm proud of my work and hope to continuously improve my older work, as it is never actually finished.
In developing coursework for UW's "ME 439: Introduction to Robotics" class, I used an à la mode board which interfaces well with a Raspberry Pi and has headers available for stepper motor control. The goal was to take a picture drawn in a vector drawing program and have the arm draw the same image. Using Python, I parsed SVG output files into a trajectory controller that moved the arm via inverse kinematics. We never really got a consistent drawing because the stepper motors had low resolution and the robots linkages weren't very robust.
At the University of Wisconsin - Stout's Research in Robotics for Assistive Technology REU, I had the privelage to spend a summer in Menomonie, Wi researching solutions in wheelchair technology. Current navigation systems use lidar or GPS for tracking, neither of which work well for fine tuning sidewalk trajectory.
I chose my handy Raspberry Pi to tackle the problem. Using a webcam and computer vision, I put together an algorithm that detected the center of a sidewalk and encouraged the user to follow it. The trick is to use Lab color space. You can find the "distance" between colors by using euclidean distance. The algorithm is as follows:
I was really excited to get the raspberry pi integrated with the wheelchair, but the control system was too proprietary for the limited time I had to hack at it.Github Repo
Biomedical Engineering Design provides oppurtunities to flex your engineering muscles...or fingers. Our client, a prosthetic artist, wanted a functional two joint finger cap that was capable of articulation. Myself and 3 others brainstormed possibilities and came up with a 3d printed inner mechanism that moved relative to the more proximal residuum. This device is enclosed by the artists silicone ccover that makes it look like nothing happened. I learned the intricacies of stereolithographic 3d printing and how to apply proper tolerances to a CAD model with appropriate linkage properties.
I created a simple circuit that sampled a piezo sensor to measure steps. It was placed on the side of a shoe and an arduino communicated with a beacon via radio transciever. I wrote a Matlab script to display gait frequency in real time.
My introductory project in the Adamczyk lab with a Masters student. The Pedarx insole we have will malfunction in trials. A few out of 99 cells will occasionally spike or zero. To fix this I employed a pattern based interpolation in Matlab.
Spring Break 2017 was spent in the Rockies with my friends and girlfriend, Zoe. We hiked trails around Boulder and Golden, then The Badlands and Mount Rushmore. We also spent a day skiing Copper Mountain.
We just need to visit Connecticut to hit 3/3 states that start with 'c'. Zoe and I flew into LA and spent a day at UCLA and USC and a night at the Griffith Observatory. We shopped West Hollywood, visited the zoo and surfed Venice Beach. We took the coastline drive up to San Francisco and stopped at Stanford before getting lost in Google's campus. I highly recommend Urban Putt and the wave organ!
I'm happiest when I solve a problem. There's no feeling like taking a step back and thinking, "I did this". I'm proud of the work I've put into making myself a better person in my years at The University of Wisconsin. As a biomedical engineer, my life goal is to help others. The seemingly endless study sessions, data analysis, and product design are worth seeing someone's face light up when I'm able to help. By taking advantage of ever-smarter technology, I'd like to see every person in the world reach their full physical potential.
In my spare time, I enjoy cooking, trying new restaurants, weightlifting, fixing things, and anything DIY.
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