- PhD Defense: Redundant Design and Adaptive Control of an Interleaved Continuum Rigid Manipulator
- PhD Preliminary Examination
- IEEE ICRA 2015: Closed Loop Task-Space Control of an Interleaved Manipulator
- ZeroG Team
I am currently a PhD candidate in mechanical engineering at the University of Wisconsin – Madison with Prof. Mike Zinn. We work in the Robotics and Intelligent Systems Lab and are generally interested in the modeling and design of automated medical intervention devices—medical robotics.
My four years at the University of Wisconsin – Madison were a great experience and I had many opportunities to develop my engineering skill set. Highlighted here are my academic studies, research for Prof. Sanders, and experience with the Zero Gravity team.
University of Wisconsin – Madison
I graduated in December of 2010 with a B.S. in Engineering Mechnics and Astronautics and a Computer Science minor. I greatly enjoy engineering and it is the myriad challenges in designing space-based systems that hold my interest. My experiences with Prof. Sanders and the ZeroG team motivated my pursuit of graduate engineering studies and formed my desire for a career in engineering research. I am cautiously optimistic on the future of NASA and commercial space endeavours, and I do believe that we can chart an economically sustainable path beyond Earth orbit. Our future is in space; I hope to enable a small part of our continued exploration.
About EMA: EMA is similar to Aerospace and Mechanical engineering but emphasizes the underlying physical principles over applied results. (So an ME may be taught the applications and limitations of an internal combustion engine while an EM receives less-specialized knowledge. An EM may be less familiar with current industry practices but can more easily design an analyze new systems for which industry has not yet embraced.) The Astronautics specification provides additional coursework in dynamics and orbital- and fluid-mechanics.
Engine Research Center
I worked with Professor Scott Sanders and his group in the ERC throughout my undergrad. Our research looked to create sensors that quickly measure combustion systems. These tools allow engine designers to verify engine performance and critique their design metrics. These methods can also be applied to other dynamic systems; eg. rocket engines. Here’s an overview poster [.pdf].
Creation of a Fiber Optic Thermometer for Widespread Commercial Use in Internal Combustion Engines
Our research engines have windows in the cylinder walls to allow direct observation of combustion but many other engines do not have this convenience. LaVision, GmbH. has developed an optical spark plug to provide optical access to an engine while retaining normal spark plug function. With LaVision, we’ve developed a hyperspectral sensor to measure engine combustion in any spark-ignited engine (truck, car, jeep, lawnmower, etc.).
Hyperspectral Absorption Spectroscopy Overview [.pptx, 4.6MB] — Describes the basic technique and theory.
Source and Sensor Development [.pdf, 1.6MB] — A hardware-centric description of the source and sensor. This includes some preliminary results.
High Speed Grating Spectrometer
Combustion can be a dirty process and as the engine runs soot can accumulate in the optical path. There are a few ways to overcome this, this design simply threw power at it (up to 0.5 W broadband). The sensor generated broadband light (1333-1373nm) centered on the ‘R’ H2O absorption branch and sent it through a sample. The concentration, temperature, and pressure of water in the sample caused some wavelengths to be absorbed, altering the broadband signal. This alteration is recorded by a 14kHz infrared linescan camera attached to a grating spectrometer. Comparing the altered signal to simulated water absorption measurments allows the concentration, temperature, and pressure of the water in the sample to be determined.
High Speed Grating Spectrometer [.pdf 99MB]
Visualizing Fiber Mode Movement in Multi-mode Fiber
A common problem in our applications is ‘catching’ all of the light sent through a sample. Beamsteering (the bending of light due to inhomogeneous engine conditions) limits the amount of light that we can capture in the output fiber. Enlarging the diameter of the fiber is the simple solution but mode noise is encountered in diameters beyond 10μm. Mode noise results from the light interfering with itself and dominates other noise sources in the system, as shown in the animation (right) and picture. A single-mode fiber would lack the black and white variations in intensity, appearing to be uniformly illuminated. This investigation with former M.S. student Renatta Bartula tried to qualify the mode movement but was unable to remove the mode noise through post-processing.
The University of Wisconsin ZeroGravity Team develops, conducts, and analyzes microgravity experiments as participants in NASA’s Reduced Gravity Student Flight Opportunities Program. I flew with the experiment my freshman and sophomore years and co-lead the Linear Spray Cooling experiment with Lisa McGill. My involvement has been very rewarding and I have enjoyed considering and hopefully minimizing the effect of gravity on our experiments. Here are brief summaries and documents of the last two experiments:
Linear Spray CoolingAs computer processors, power amplifiers, laser diodes, and similar devices increase in performance they are also becoming smaller. Since these devices are not 100% efficient some of the input energy is lost as heat which is increasingly concentrated due to shrinking size. Removing this thermal energy is essential to the continued operation of these devices but current methods are fundamentally limited in their heat transfer capability. Specifically, forced air convection cooling quickly requires absurd velocities to cool high heat flux devices and liquid cooling breaks down when vaporized liquid prevents cool liquid from contacting the hot surface. Linear spray cooling is a two-phase technique that shoots coolant droplets at the heated surface and uses their inertia to prevent the formation of a vapor bubble. Working with Professor Tim Shedd we showed that coolant flow rate is the primary determinant of a linear spray cooling system’s performance and that the influence of gravity is minor (2.6% at the largest). While further work is needed, there does not appear to be any fundamental reason that would prevent linear spray cooling from being used in satellites, on the International Space Station, and in variable-gravity environments (fly-by-wire aircraft for instance).
SPESIF 2009 Presentation [.ppt 4.0MB] — John Springmann, Lisa McGill, and I presented this work at the Space, Propulsion, and Energy Sciences International Forum in Huntsville, AL this past February. See also our proceedings paper.
This experiment investigated fluid movement due to surface tension in a microgravity environment. In short, the surface tension forces responsible for meniscii and capillary action in plants are much more significant when gravity is removed. If a rocket’s liquid fuel tank was a rectangular box, upon reaching orbit surface tension would cause a significant portion (perhaps 10%) of the fuel to be stuck in the corners of the tank where it cannot be reached by the outlet. Better tank design would eliminate these interior corners to allow all the fuel to be used. Another application would be to design tubes to transport liquids without pumps, much as trees or heat pipes do.
WSGC 2007 Presentation [.ppt 7.5MB] — Eric Leigel and myself presented our findings at the 2007 Wisconsin Space Grant Consortium Conference at UW-Superior.