Research

My research interests center around biologically inspired motor control for dynamic tasks. These include robot locomotion (e.g. walking, running, flying) as well as robotic manipulation and upper body humanoid motor control. Check out some of the current and past projects that I've been involved with:

ROBOTIC FLAPPING-WING FLIGHT (Current)


 

At the end of the 15 th century, a man by the name of Leonardo da Vinci grew an inspiration to realize one of the oldest engineering fantasies as he attempted the design of a flapping-wing flying machine. Even more amazing is the fact that more than five hundred years after da Vinci's initial work, flapping-wing flight still remains an open problem. Although humans have had the capability of flight for about a century, with the help of various aircraft, we have yet to fully understand or mimic the phenomenon of bird flight.

Modern aerodynamic theory is based on separating the roles of lift and propulsion by attaching engines to rigid aerodynamic frames, as can be seen on commercial aircraft with large thrusters mounted beneath each wing. The engines provide the necessary propulsion that is required to obtain lift from the rigid wings, which allows the use of conventional aerodynamic theory based on fixed wings in a steady airflow. Flapping wings, on the other hand, differ significantly in that they create both the lift and propulsion necessary to sustain flight while interacting with highly unsteady airflows. In this context, conventional aerodynamic theory breaks down due to the complex interactions between unsteady airflows, flexible wing membranes, and high degrees of under actuation.

Given that the dynamics of flapping-wing flight remains an incompletely understood theoretical topic, machine learning becomes an attractive candidate for addressing this type of problem. Using tools from machine learning, we hope to exploit the natural dynamics of flapping-wing flight without requiring an explicit model of them, and moreover, design a robotic bird that continually learns and improves its flight performance through experience. More on the project here.

 

QUADRUPED LOCOMOTION (Fall 2005)


  Efficient and roboust legged locomotion has always been an interesting but difficult problem to address, given the high degree of uncertainty and complex dynamics that arise in traversing rough terrain. Although some information about the world may be available, through various types of feedback sensing, it is never exact and we cannot heavily rely on the accuracy of this information. The aim of the quadruped Little Dog project is to combine methods in optimal control and reinforcement learning in order to create a system that reliably achieves legged locomotion over rough terrain in spite of noisy and unstructured environments.

 

AUTONOMOUS MOBILE MANIPULATION (Summer 2005)


  I spent the summer of 2005 at the NASA Johnson Space Center in Houston, Texas where I worked on humanoid robot manipulation. The goal was to begin initial investigations into autonomous manipulation capabilities for an upper torso humanoid robot (Robonaut), which was mounted on a mobile base. This project was in its initial stages and was a collaborative effort that included NASA, MIT, and the University of Massachusetts Amherst , among others. During my summer at NASA, I developed a simulator for the mobile version of Robonaut, as well as the core control algorithms for autonomous manipulation capabilities. The implementation consisted of fundamental control algorithms that I helped develop during my stay in Japan . Furthermore, I extended these control algorithms to incorporate posture control for the robot, including its mobile base, as well as fundamental grasping controllers that allowed the robot to reach and grasp a particular object of interest.

 

HUMANOID ROBOT CONTROL (2004)


  After graduating in 2004, I continued my research in collaboration with the CLMC Lab at ATR's Department of Humanoid Robotics and Computational Neuroscience in Japan. This research was an extension of our work on redundancy resolution for the full body 30 degree of freedom humanoid robot DB (Dynamic Brain). The goal of the project was to develop a robust controller that resolved redundancies in a task specific way, with plans of extending the theory to humanoid biped locomotion. A thorough emperical evaluation allowed us to develop some novel approaches for controlling redundant robots and subsequently work began on biped balancing and locomotion.

 

CONTROL OF ROBOTIC MANIPULATORS (2003-2004)


 

During the 2003-2004 semesters, I was a member of the Computational Learning and Motor Control Lab (CLMC) at USC, under the supervision of Dr. Stefan Schaal. My research emphasis centered around dynamic motor control of redundant robots. Redundant robots essentially posses more degrees of freedom than are required to execute a given task. This means there are an infinite number of ways that a robotic arm, for example, can generate joint trajectories that will allow it to track a given target with its fingertip. This becomes an extremely important issue when dealing with high degree of freedom systems such as humanoid robots.

 

My earlier research internships were as far away from robotics as you could ever hope to get, but still a lot of fun nonetheless...

NETWORK SECURITY (Summer 2002/2003)


 

I was a student intern for two consecutive summers at the MIT Lincoln Laboratory. My work during the first summer involved working with intrusion detection systems, which are systems that monitor computer network traffic and generate alerts in the event of a suspected attack on the network. I focused on understanding the behavior of these systems for the purpose of modeling their activity and simulating a large network of detection sensors. During my second summer, I implemented a kernel module for the Linux operating system. The purpose of this module was to detect network attacks originating from buffer overflows in which the attacker can modify the return address of the program to point to his supplied malicious assembly code.

 

SIMULATION OF NON-VOLATILE MEMORY (Summer 2001)


  I spent the summer after my sophomore year at the Caltech Thomas Watson Laboratories of Applied Physics by means of the Student Undergraduate Research Fellowship (SURF). The research emphasis was on analyzing the effects of a new type of non-volatile memory device based on silicone nanocrystals. I was given the task of simulating the electrical charge injection and discharging processes in order to examine the characteristics of charge storage in a nanocrystal containing surface. The purpose of the simulation was to help determine the exact location of charge trapping sites as well as establish whether injected charge was dissipated laterally across the nanocrystal surface or into the silicon substrate.