Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Scientists develop method for verifying safety of computer-controlled devices

Researchers at Carnegie Mellon University's School of Computer Science have developed a new method for systematically identifying bugs in aircraft collision avoidance systems, high-speed train controls and other complex, computer-controlled devices, collectively known as cyber-physical systems (CPS).

The approach, developed by University Professor of Computer Science Edmund M. Clarke and Andre Platzer, assistant professor of computer science, already has detected a flaw in aircraft collision avoidance maneuvers —since corrected — that could have caused mid-air collisions.

It also has verified the soundness of the European Train Control System. Ultimately, the method could be used on other cyber-physical systems, such as robotic surgery devices and nano-level manufacturing equipment.

"Engineers increasingly are relying on computers to improve the safety and precision of physical systems that must interact with the real world, whether they be adaptive cruise controls in automobiles or machines that monitor critically ill patients," Clarke said. "With systems becoming more and more complex, mere trial-and-error testing is unlikely to detect subtle problems in system design that can cause disastrous malfunctions. Our method is the first that can prove these complex cyber-physical systems operate as intended, or else generate counterexamples of how they can fail using computer simulation."

In the case of aircraft collision avoidance systems, for instance, Platzer and Clarke used their method to analyze so-called roundabout maneuvers. When two aircraft are on rapidly converging paths, one technique for avoiding collisions is for the system to order each pilot to turn right and then circle to the left until the aircraft can safely turn right again to resume their original paths. It's as if the aircraft are following a large traffic circle, or rotary, in the sky. But analysis by the Carnegie Mellon researchers identified a counterexample: when aircraft approach each other at certain angles, the roundabout maneuver actually creates a new collision course that, in the few seconds remaining before their paths cross, the pilots might not have time to recognize.

Like Model Checking, a method pioneered by Clarke that today is the most widely used technique for detecting and diagnosing errors in complex hardware and software design, the new method analyzes the logic underlying the system design, much as a mathematician uses a proof to determine that a theorem is correct. Clarke shared the 2007 A.M. Turing Award, generally considered the computer science equivalent of the Nobel Prize, for his role in developing Model Checking.

A crucial difference, however, is that Model Checking can examine every possible state of a discrete finite-state system, such as a new circuit design for a computer chip; that's not possible for a CPS that must interact with the infinitely variable real world. Even if the differential equations that govern these systems can be solved — and they often can't — it usually is impossible to use the results to predict the behavior of the system, Platzer said. Instead, he and Clarke have developed algorithms that decompose the systems until they produce differential invariants — mathematical descriptions of parts of the system that always remain the same. These differential invariants, in turn, can be used to prove the global logic of the CPS.

"When the system design is sound, as we found in the case of the European control system for train traffic or the repaired flight controller, our method can provide conclusive proof," Platzer said. Likewise, when flaws exist, the method reliably generates counterexamples. "Finding the counterexamples is actually the easy part," he added. "Proving that they are fixed is hard."

The demand for methods that can prove a CPS or hybrid system operates as intended will only increase as these systems become more numerous and more crucial for everyday life, Platzer said. "Bugs in complex cyber-physical systems like cars, aircraft, chips or medical devices are expensive to fix and may endanger human life," he explained. "In transportation, the percentage of development cost spent on design and testing new control software is already well above 50 percent and is steadily rising."

The National Science Foundation (NSF) has identified the design and verification of CPS as a key area of research. The increasing use of robotic devices, the growth of sensor networks, the proposed creation of a "smart grid" for delivering electrical power, a greater reliance on automated war fighting and growing use of efficient, "zero-net-energy" buildings are all examples of a growing reliance on computer control systems that are tightly coupled to physical systems. This work was sponsored, in part, by the NSF and the German Research Council.

About Carnegie Mellon: Carnegie Mellon is a private research university with a distinctive mix of programs in engineering, computer science, robotics, business, public policy, science and social science, fine arts and the humanities. More than 11,000 undergraduate and graduate students receive an education characterized by its focus on creating and implementing solutions for real problems, interdisciplinary collaboration, and innovation. A small student-to-faculty ratio provides an opportunity for close interaction between students and professors. While technology is pervasive on its 145-acre Pittsburgh campus, Carnegie Mellon is also distinctive among leading research universities for the world-renowned programs in its College of Fine Arts. A global university, Carnegie Mellon has campuses California's Silicon Valley and Qatar, and programs in Asia, Australia and Europe.

Byron Spice | EurekAlert!
Further information:

All articles from Information Technology >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Resolving the mystery of preeclampsia

21.10.2016 | Health and Medicine

Stanford researchers create new special-purpose computer that may someday save us billions

21.10.2016 | Information Technology

From ancient fossils to future cars

21.10.2016 | Materials Sciences

More VideoLinks >>>