Public Release: 

UT Arlington work to safeguard cyber-physical systems made with legacy subsystems

Avoiding errors

University of Texas at Arlington


IMAGE: Taylor T. Johnson, a University of Texas at Arlington assistant professor of the Computer Science and engineering. view more

Credit: UT Arlington

A University of Texas at Arlington computer scientist will work to ensure that using legacy components in cyber-physical systems - those that have been reused from prior versions of a cyber-physical system in subsequent versions - will not result in failures due to unforeseen requirements made between software and physical components.

Taylor T. Johnson, an assistant professor in the Computer Science and Engineering Department, will use a $397,807 grant from the Air Force Office of Scientific Research to develop formal methods that will automate the identification of cyber-physical systems specification mismatches to enable safe upgrades of those systems consisting of old and new subsystems.

A cyber-physical system is one that has collaborating computational elements controlling physical entities. Examples include automobiles, aircraft, unmanned vehicles or medical devices.

Many times, when a new version of an aircraft or automobile comes out, the new system is built by reusing parts of the old system. Johnson hopes to identify those potential mismatches that engineers will have to address.

"When we control the physical world through software, the system developers frequently make implicit assumptions about the physical environment that the software will operate within. Because we've made assumptions about the physical world in the cyber domain, there is a possibility of reusing a component from one version to the next in ways that violate these implicit physical assumptions," Johnson said. "This research will determine how to inform the software of differences in physical specifications, using, in-part, physical environment information as input. On a given system, we want to infer the software's implicitly encoded assumptions about the physical world and ensure these match with the actual physical requirements."

An example of cyber-physical specification mismatch occurred in 1996, when the European Space Agency's Ariane 5 rocket control software failed after liftoff.

Software and hardware components in the rocket had been re-used from the Ariane 4. A software module in an inertial measurement unit had been programmed under an assumption that the velocity of the rocket was bounded in a certain way, which would limit the value of a software variable.

However, Ariane 5 had drastically different physical operating requirements, which caused this unchecked variable to overflow, and eventually led to the destruction of Ariane 5.

Often, in the automotive, aerospace and medical device domains, components from previous versions of a system are reused in successive iterations. Because these components were created and integrated into a specific system and use-case, changes to the system may cause those components to interact in unintended ways or fail when inputs from the physical world are applied.

Khosrow Behbehani, dean of the College of Engineering, underscored the importance of Johnson's research.

"Often, engineers make educated assumptions based upon past experience," Behbehani said. "However, technology changes quickly, and it becomes difficult to predict future performance based on past results because the demands on the design and function change. Dr. Johnson's research will help future engineers more confidently create systems that may safely be upgraded with limited financial or safety concerns."

Johnson has carved a niche at UTA in this area of cyber-physical systems, pulling in more than $1.5 million from various funding entities to address safety, security and reliability of cyber-physical systems.


About The University of Texas at Arlington

The University of Texas at Arlington is a comprehensive research institution of more than 51,000 students in campus-based and online degree programs and is the second largest institution in The University of Texas System. The Chronicle of Higher Education ranked UT Arlington as one of the 20 fastest-growing public research universities in the nation in 2014. U.S. News & World Report ranks UT Arlington fifth in the nation for undergraduate diversity. The University is a Hispanic-Serving Institution and is ranked as a "Best for Vets" college by Military Times magazine. Visit to learn more, and find UT Arlington rankings and recognition at

Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.