My name is Nathan Donahue and I graduated from the University of Utah with a masters of science degree in Mechanical Engineering emphasizing in Robotics and Controls (3.973 GPA).  My education has given me a well-rounded set of skills that encompasses mechanical engineering, electrical engineering, and computer science.  Below are some photos and descriptions of some different personal and school projects I have worked on.  (Does NOT include professional work.) 

 
 
 
 
 

 

MIDI Step-Sequencer

Designing and building a 8-channel 32-step MIDI sequencer for music production utilizing a off-the-shelf matrix of individually addressable RGB LEDs.  The goal is to create a sequencer that has a more instrument like feel with absolutely no menus to dive into while playing/programming.   Custom circuits and PCBs were created using KiCad and manufactured at OSH Park.   Serial and Parallel shift registers are used for the 60 tactile button switches.  
 
 
 
 
 
 

 

Timelapse Motion-Control Robot For Photography

Robot is controlled via WebSocket protocol through smartphones, tablets, or computers through a web browser which displays the various user interfaces.   The angular resolution of the robot is 40.75 arc-seconds.  (Raspberry PI, Linux, Python, JavaScript, HTML, OpenCV, gPhoto) 
 
 
 
 

 

Poly-cylindrical Acoustic Diffusers

This is a two-dimensional array of poly-cylindrical acoustic diffusers I designed and constructed a few years ago to improve the acoustics of our living room with high ceilings.  Prior to its installation there was a distracting and harsh echo in the room.  Now the room sounds large and alive, but without the destructive interference.  I never formally studied acoustics in school and learned what I needed to know through independent study and use of the "Master Handbook of Acoustics, 5th ed." textbook.
 
 
 

 

Persistence of Vision Clock made from a VCR head and dsPIC Microcontroller:

The persistence of vision (POV) clock was a project for an advanced mechatronics class I took in graduate school.  When an array of LEDs are rotated quickly and illuminated when located at specific locations, for short time intervals, an optical illusion is created due to our persistence of vision.  A VCR head was utilized for this project because it already contained a balanced rotor as well as a rotary transformer, which can wirelessly transmit signals/power eliminating the need for sliprings.  The report for this project can be downloaded here.

 

 
 
 
 
 

 

Wireless Relay Module for Home Automation Using esp8266 Microcontroller

An internet-of-things wireless relay module module for home automation was created using an esp8266 micro-controller and programmed using the Arduino software (IDE).  A local MAMP server is used to execute HTML/PHP scripts to control a family of the relay modules in interesting ways through an internet browser on a device such as a smartphone.
 
 
 

 

Tele-Operated Serial Manipulator Using Computed Torque Controller

The effectiveness of a tele-operated, slave, two-link planer manipulator, commanded complex trajectories in realtime, was investigated for both position/derivative (PD) and computed-torque control (CTC).  The performance of the CTC controller that used low-pass filtering to condition the encoder signals of the master robot was found to track the commanded trajectories exceptionally well despite the challenge of constant external disturbances and encoder signal noise.  For this application, the slave error signal was not fed back to the master robot, therefore time delay was not an issue regarding loop stability.  Report.
 
 
 

 

Autonomous Localization Feasibility Using Minimum Sensing

An iRobot Create was used to test the feasibility of using limited sensing to localize the robot within an environment for which its initial location was unknown. Idealy, once the robot localized itself, a rapidly expanding random tree (RRT) algorithm would be used to quickly generate a path to a goal position.  The programming language used was MATLAB and an Arduino Mega and Xbee pair was used to wirelessly send the sensor data using UART communication protocol.
 
 
 

 

Program to Optimize and Preview Layout of Wood Floor:

I created a program that optimizes the layout of wood flooring minimizing waste and giving the ability to preview the end result using the MATLAB programming language. 
 
 
 

 

Resonance Analysis of a Chain of 'n' Spherical Neodymium Magnets:

The potential for a chain of spherical magnets, at the mesoscale, to achieve locomotion while experiencing resonance was investigated and a simple model, which treated the magnetic forces between the magnets as though they were torsional springs, was used to simulate the different modes of vibration for chains of various lengths.  It was also thought that energy harvesting might be possible using chains of magnets and exploiting their resonant properties.  This work was completed under the supervision of Dr. Jake Abbott who is the director of the Telerobotics Laboratory at the University of Utah for a semester of independent study.  Due to lack of funding and greater interest towards studying robotics, I opted not to further pursue this project as a master's thesis or doctoral research.  The preliminary writeup for this work can be found here

 

 
 
 

 

Dr. Stewardson's Manufacturing Lab:

During my undergraduate studies in mechanical engineering at Utah State University, I had the privilege of working for a manufacturing lab within the college of engineering for 2 years under the supervision of Dr. Gary Stewardson.   I received one-on-one training for many fundamental manufacturing processes including the lathe, mill, woodworking techniques, sand-casting, soldering, etc.  I was involved in the design, manufacturing, maintenance, and repair of peculiar fixtures, simple pneumatic robots, air cannons, an electric scooter, and a Harley Davidson trike to name a few.  This was the most valuable experience I had during my undergraduate education because it helped me develop important connections between hands-on technologist and engineering based skill sets.
 
 
 

 

Sound and Noise Laboratory:

These are some photos my music making gear, which includes many guitar effects pedals I built from scratch as well as modified effects pedals on an elaborate board to house them all that I built.  Playing the guitar and experimenting with sound has been a primary hobby of mine since I was a young kid.  I have done much independent study regarding how to play the guitar, music composition, audio recording techniques, room acoustics, mic and speaker placement, etc.  Prior to studying mechanical engineering, I wanted to be a recording engineer, but I instead chose to keep it a creative hobby.