Autonomous Vehicles Can Make All Cars More Efficient

Autonomous vehicles have been highly anticipated because of the possibility that they will greatly reduce or perhaps eliminate the collisions that cause more than one million deaths each year. But safety isn’t the only potential benefit self-driving cars can offer: Teams of researchers around the world are showing that autonomous vehicles can also drive more efficiently than humans can. A U.S. Department of Energy program called NEXTCAR (Next-Generation Energy Technologies for Connected and Automated On-Road Vehicles), for example, is betting that a mix of new smart vehicle technologies can boost fuel efficiency by as much as 30 percent.

As part of the NEXTCAR program, San Antonio, Texas-based Southwest Research Institute (SwRI) showcased advances in autonomous vehicle technology that will improve vehicles’ fuel economy—including the fuel efficiency of non-autonomous automobiles that just so happen to be in traffic with autonomous ones. The demonstration was held at the ARPA-E Energy Inovation Summit in Dallas in late May.

Making an Efficient Autonomous Vehicle

The SwRI team retrofitted a 2021 Honda Clarity hybrid with basic autonomous features such as perception and localization. On the day of the summit, they drove the vehicle along a route encircling the parking lot of the convention center where the summit was held. SWRI’s Ranger localization system, which the researchers installed on the Honda, has a downward-facing camera that captures images of the ground. By initially mapping the driving surface, Ranger can later localize the vehicle with centimeter-level accuracy, using the ground’s unique “fingerprint” combined with GPS data. This precision ensures the vehicle drives with exceptional control.

“It’s almost like riding on rails,” says Stas Gankov, a researcher in SwRI’s powertrain engineering group. For this project, his group collaborated with other divisions at the institute, such as the intelligence systems division, which developed the autonomy software stack added to the Honda Clarity.

Just as important, however, was the addition of an eco-driving module, a key innovation by SwRI. The eco-mode determines the most economical driving speed by considering various factors such as traffic lights and surrounding vehicles. This system employs predictive control algorithms to help solve a tricky optimization problem: How can cars minimize energy consumption while maintaining efficient traffic flow? SwRI’s eco-mode aims to reduce unnecessary acceleration and deceleration in order to optimize energy usage without impeding other vehicles.

“Autonomous vehicles operating in eco-mode influence the driving behavior of all the cars behind them.” —Stas Gankov, Southwest Research Institute

To illustrate how the technology works, the team installed a traffic signal along the demonstration pathway. Gankov says an actual traffic light timer from a traffic signal cabinet was connected to a TV screen, providing a visual for…