The Texas A&M Transportation Institute(TTI) has developed an augmented-reality environment where real entities, such as vehicles and traffic signal operation, are combined with simulated traffic and displayed on a screen, in similar way to the Pokémon Go app, but showing simulated vehicles superimposed on the roadway.
A move toward the integration of connected and automated vehicles (CAV) is currently taking place, but to help make their widespread use a reality, the technologies need to be vetted, validated, and successfully deployed. Before that can happen, there needs to be a reliable, standardized way to test those technologies. The TTI has developed a first-of-its-kind approach called connected vehicle assessment simulation (CONVAS), which marries the cost-effectiveness of computer simulation with actual roadway operations, to produce an efficient yet dependable evaluation mechanism for the USA’s Federal Highway Administration (FHWA). TTI has been developing the platform since January 2014.
To mitigate the effects of modeling while improving reliability under actual driving conditions, TTI research engineer Srinivasa Sunkari, principal investigator on the project, and his team used hardware-in-the-loop (HITL) simulation, which introduces hardware components into the simulation model. In HITL, devices like traffic signals are fed information, such as simulated data indicating a vehicle is passing a detector, and the signals react in real time. That reaction is then fed back into the simulation model, and the simulated vehicle proceeds or stops accordingly. The TTI team developed an enhanced HITL simulation by incorporating an actual CV on a roadway network into a simulation model, and displaying simulated CVs inside the real vehicle at the same time, allowing assessments of how CVs respond to each other.
To more accurately represent CV communications, TTI researchers integrated PTV’s microscopic traffic simulator Vissim with the ‘ns-3’ open-source wireless network simulator. Doing so enables simulated vehicles to adapt to variability in the communication environment, providing a more realistic assessment of CV applications in the simulation model. On June 22, 2016, Sunkari and his team demonstrated CONVAS to visiting FHWA sponsors at Texas A&M’s RELLIS Campus. The field test confirmed the successful integration of the Vissim and ns-3 simulators, and showed the seamless data flow between the simulation model and the test vehicle’s onboard unit. With the delivery of CONVAS in December, FHWA now has a way to test the realistic impact of wireless communications on the performance of large-scale CV applications while minimizing evaluation costs.
“The limitations of traditional simulation come from having to model every entity to be as realistic as possible. CONVAS provides the most advanced, realistic evaluation tool for emerging CV/AV applications that rely on wireless communications,” explained Sunkari. “And in the future, that’ll be just about every aspect of our transportation system.”
FHWA highway research engineer Peter Huang, who manages the Turner-Fairbank Intelligent Intersection Traffic Control Laboratory, noted, “The technology used in developing this platform will bring benefits in CV research for many years to come as we work to improve our transportation network to become a more intelligent, more reliable and safer system.”
