Learn more about Ryan Williams
Coordinating leaderless teams
Imagine a team with no leader and how critical communication becomes. Every team member must communicate with every other member or the team risks failure. Ryan Williams works with leaderless teams like this, except that his teams are robots. He works on controlling teams of fully-autonomous mobile robots that have no central controller. “Decentralization makes it significantly more difficult,” according to Williams. “You have to really diffuse information in the network.”
Williams has created control algorithms that can guarantee useful behaviors from teams of robots by ensuring that all robots can communicate with each other, even when their physical locations impede communication. It’s simpler if every robot can communicate directly with every other robot, he explains, but his research focuses on the cases when some robots might be cut off from communicating with some robotic teammates.
Using his algorithms, some communications may need multiple hops, but ultimately “every robot can communicate with every other robot,” he says. Adding complexity, Williams is also working with heterogeneous interaction: when two kinds of robots (mobile robot and static nodes) need to communicate. “We’ve also recently started to consider cases when the robots are different in how they move or communicate,” he says.
One primary task for the robot teams is moving in a rigid formation. “If they are rigid, they can hold a load,” he explains. “If they can fly in formation, they can do everything.” It’s not as simple as just moving robots together, however. Williams’ robots must change formations as they work. “Formation and shape control is a means of cohesive and persistent motion for a team.” he explains.
Williams’ work can apply to any multi-robot system, whether underwater, in the air, or on the ground. “Most roboticists concentrate on really cool stuff for single robots,” he says. “I concentrate on what happens when you take robots that do cool things by themselves and put them together.”
Ryan Williams (CPE ’05) always knew that he wanted to study engineering. “From a young age, I was always creating things, building things,” he recalls. “I think it’s embedded in my personality. I just like solving problems.”
The Roanoke native will earn his Ph.D. in EE this summer from the University of Southern California (USC), where he is focusing on autonomous robotics.
Williams’ interest in robotics developed during his senior year in ECE, when he was offered the opportunity to work with Professor Daniel Stilwell as an undergraduate researcher in the Autonomous Systems and Controls Laboratory (ASCL).
Williams says his time working with Daniel Stilwell was "one of the most rewarding and influential periods of my life.
Williams worked on a prototype for an autonomous underwater vehicle (AUV), helping to design the craft’s inertial measurement unit (IMU), which collects the data for steering. He gained experience testing the prototype in the lab and in the field, and completed an undergraduate thesis on AUV navigation.
Shortly before his graduation, ASCL was awarded a grant from the Navy to build the world’s first high-speed AUV. Williams decided to stay on for a year as a research engineer to lead circuit-board design and software-development efforts.
In 2006, Williams received a fellowship to continue his studies as a doctoral student at USC’s Robotic Embedded Systems Laboratory. In his free time, he enjoyed exploring his new West Coast home. The former high school athlete was smitten with the California mentality and quickly took up golfing, swimming, and surfing.
But on Jan. 27, 2008, his active lifestyle ended with a life-changing accident. While surfing, Williams was launched headfirst by a wave into a hidden sandbar. He sustained a broken neck that rendered him paralyzed in all four limbs.
Williams returned home to Roanoke and embarked on two grueling years of rehab, while continuing his education through USC’s distance education program. He suspended his research and took one class per semester during his recovery.
Adjusting to a new normal
“It was obviously a catastrophic injury,” says Williams, “but you don’t really realize the impact it has on your body. It impacts all of your body’s systems. It makes you sick and tired. I was physically ill for a long time.”
Adjusting to his new normal was physically and mentally trying. “I have no hand function at all,” explains Williams. “I have a cuff that I wear on my right hand with a pencil. I can type at 20-30 words per minute. It’s very difficult, still to this day.”
“I used to love to write, especially mathematical work. I would think via paper. When you can’t move ideas from your brain to a form of reality easily, it makes things exponentially harder. I had to learn to solve many problems in my head. When I’m at my desk, I’m just sitting there. I just think and think and think.”
But even during his most challenging days, Williams never considered discontinuing his education. “Dropping out was not an option,” he says. “Giving up does not compute.”
Passion for research
Williams persevered, one class at a time, for three years until the completion of his coursework. He resumed research in 2011, switching his concentration from underwater robots to multi-agent coordination and control.
Williams gave an ECE graduate seminar on his research in robotic control this spring.
He has published 11 conference and journal articles and he has attended the IEEE International Conference on Robotics and Automation and the IEEE/RSJ International Conference on Intelligent Robots and Systems multiple times.
This spring, Williams returned to ECE to deliver a graduate seminar on interaction and topology in multi-agent coordination. It was a happy homecoming for Williams, who still keeps in touch with Stilwell and regards his time at Virginia Tech as “one of the most rewarding and influential periods of my life.”
Postgraduation, Williams hopes to secure a professorship and continue his line of research. “There are a lot of problems that remain unsolved,” he says. “What’s going to turn the tide is when robots can reliably aid society—without human intervention.”