Research Interests

Presently, I am interested in defining and deriving robust and stable motions for agile legged robots on a variety of terrain. For bipedal walking, researchers use mechanical insights such as the zero moment point(ZMP) and human walking studies to pursue such gaits. We can also look at the eigenvalues of approximations to the biped gait to guide our designs. Traditional approaches treat all uncertainty in the robot model and the environment as a disturbance to the system. I believe we can represent our uncertainty more precisely and identify trajectories that are robust under our uncertainty, without incurring the costs of POMDPs or even deterministic global policy search algorithms. Currently I am looking at gradient descent-based nonlinear optimal control methods. Given a task definition, we should be able to simultaneously optimize several variations on the model using the same control inputs to find a trajectory that works for all of them.

My advisor for this research is Chris Atkeson.

My past research has taken me in several different directions. Before coming to CMU, I worked on the ScriptEase project at the University of Alberta, doing research in visual programming languages to support storytelling in video games.

The need motivating this work is that interesting interactive video game scenarios require game characters and objects to be scripted. Video game designers rely on programmers to write scripts to realize their design vision. During the game development process, programmer time is often the bottleneck resource, and gameplay development cycle times are lengthened when designers must wait for programmers to implement their ideas. Our testbed was the computer role-playing game Neverwinter Nights by BioWare Corp. We identified design patterns in role playing games and designed ScriptEase, a visual scripting tool intended to allow video game designers to perform previously infeasible scripting tasks to tell their stories.

ScriptEase was released to the game user community as a complement to the level editing tools that are shipped with Neverwinter Nights. I was responsible for the design, implementation, overall quality assurance, and release. I monitored online discussion forums to communicate with the user community, eliciting feedback to incorporate into future revisions.

We also evaluated ScriptEase with a high school English class. The students used ScriptEase and its CRPG design patterns to write an interactive short story. ScriptEase has also been used in summer camps for interactive story telling.

For my M.Sc. at the University of Alberta I tackled the multiple sequence alignment problem of computational biology. The motivating question is: given two pieces of DNA that encode similar proteins between two different organisms, how can we determine the likely sequence of mutations  that turned the DNA from one organism into the other? Answering this question allows us to identify the origin of genetic diseases in humans, map taxonomic relationships between species, and to posit the biological functions of new proteins.

At Alberta I also worked on our RoboCup team, Team Canuck for the small-size league. We innovated in the design of simple, reliable distributed communications among independent agents. Our vision system was among the best, and we advanced to the quarter finals in 2004, before I retired from this effort.