4/27/2010 By Susan Kantor, ECE ILLINOIS
Written by By Susan Kantor, ECE ILLINOIS
Sometimes, cars or aircrafts are recalled because some bug in the system is found that compromises the reliability of the vehicle. ECE Assistant Professor Sayan Mitra research may make these problems less frequent.
Mitra researches cyber-physical systems, which is a newly coined term for complex computing systems that interact with physical processes, such as the controller in a car for its braking system. Typically these systems have dozens of computers, sensors, and actuators that ultimately control a physical process, in this case, the motion of the vehicle.
Mitra is looking at how to guarantee the reliability of these systems through principled design and verification.
“The flavor of our work is distinct in that we focus on rigorous modeling and proofs as opposed to simulations,” he said.
Two different time-scales and two different types of mathematics are involved. Computations happen at the rate of nanoseconds, while physical processes—like a car’s velocity—changes at a slower rate. Physical processes are continuous while programs are not: very small changes in the inputs to a program can produce dramatically different results. Consequently, the mathematical modeling of these systems has been a problem because computer scientists have worked on certain "discrete’’ models, while control systems researchers have worked with differential equations.
In his PhD work, Mitra looked at specifying state machines, data structures, and differential equations using one unified mathematical language. The next step is to design systems that are correct by construction or guarantee the correctness of systems within this framework. The key challenge here is to automatically develop abstract models of the system that are faithful to the original and are also tractable. Mitra is now developing software tools and algorithms towards this end.
“Transportation is one field where this technology is likely to find applications as software-based controllers become more sophisticated and reliability assurances are crucial,” Mitra said.
Mitra and his collaborators in the Department of Computer Science are working with John Deere to design reliable controllers for its off-road vehicles. He is also working with Rockwell Collins on developing and verifying distributed air-traffic control protocols for small airports.
“These protocols are rather complicated because many different aircrafts may approach simultaneously from different directions,” Mitra said. “How do they interact? How do the air traffic controllers set priorities for these aircrafts so that nothing bad ever happens?”
They hope to develop a set of software tools with an intuitive interface so that engineers will be able to model these systems, find and eliminate design bugs, and ultimately verify their correctness.
“This research interests me because it brings together ideas and tools from two historically distinct disciplines and because it provides useful techniques for designing reliable systems” he said.
He added that undergraduates who are interested in this area should talk to him about research opportunities.