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:

More articles from Information Technology:

nachricht Green Light for Galaxy Europe
15.03.2018 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht Tokyo Tech's six-legged robots get closer to nature
12.03.2018 | Tokyo Institute of Technology

All articles from Information Technology >>>

The most recent press releases about innovation >>>

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

Im Focus: Locomotion control with photopigments

Researchers from Göttingen University discover additional function of opsins

Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...

Im Focus: Surveying the Arctic: Tracking down carbon particles

Researchers embark on aerial campaign over Northeast Greenland

On 15 March, the AWI research aeroplane Polar 5 will depart for Greenland. Concentrating on the furthest northeast region of the island, an international team...

Im Focus: Unique Insights into the Antarctic Ice Shelf System

Data collected on ocean-ice interactions in the little-researched regions of the far south

The world’s second-largest ice shelf was the destination for a Polarstern expedition that ended in Punta Arenas, Chile on 14th March 2018. Oceanographers from...

Im Focus: ILA 2018: Laser alternative to hexavalent chromium coating

At the 2018 ILA Berlin Air Show from April 25–29, the Fraunhofer Institute for Laser Technology ILT is showcasing extreme high-speed Laser Material Deposition (EHLA): A video documents how for metal components that are highly loaded, EHLA has already proved itself as an alternative to hard chrome plating, which is now allowed only under special conditions.

When the EU restricted the use of hexavalent chromium compounds to special applications requiring authorization, the move prompted a rethink in the surface...

Im Focus: Radar for navigation support from autonomous flying drones

At the ILA Berlin, hall 4, booth 202, Fraunhofer FHR will present two radar sensors for navigation support of drones. The sensors are valuable components in the implementation of autonomous flying drones: they function as obstacle detectors to prevent collisions. Radar sensors also operate reliably in restricted visibility, e.g. in foggy or dusty conditions. Due to their ability to measure distances with high precision, the radar sensors can also be used as altimeters when other sources of information such as barometers or GPS are not available or cannot operate optimally.

Drones play an increasingly important role in the area of logistics and services. Well-known logistic companies place great hope in these compact, aerial...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

Ultrafast Wireless and Chip Design at the DATE Conference in Dresden

16.03.2018 | Event News

International Tinnitus Conference of the Tinnitus Research Initiative in Regensburg

13.03.2018 | Event News

International Virtual Reality Conference “IEEE VR 2018” comes to Reutlingen, Germany

08.03.2018 | Event News

Latest News

Wandering greenhouse gas

16.03.2018 | Earth Sciences

'Frequency combs' ID chemicals within the mid-infrared spectral region

16.03.2018 | Physics and Astronomy

Biologists unravel another mystery of what makes DNA go 'loopy'

16.03.2018 | Life Sciences

Science & Research
Overview of more VideoLinks >>>