Vehicle efficiency improvements are genrally accomplished by incrementally modifying components and control systems — often at a cost of millions of dollars. But now, a team led by Southwest Research Institute has applied connectivity and automation to achieve a 20% improvement in efficiency on a 2017 Toyota Prius Prime.
Working with collaborators at the University of Michigan and Toyota Motor North America, the team is sponsored by the Advanced Research Projects Agency – Energy as part of its Next-Generation Energy Technologies for Connected and Automated On-Road Vehicles program. The program to develop enabling technologies set forth an ambitious target: To reduce the energy consumption of the Prius Prime by 20% without making changes to the powertrain and without compromising emissions, safety or drivability.
“We knew these tools had the potential for making a big impact on fuel efficiency,” said Sankar Rengarajan, manager of SwRI’s Powertrain Controls Section. “Vehicle connectivity and automation are already being used to effectively improve vehicle safety and driver convenience. For this program, we were able to tap into those existing data streams and put the information to use in a new way.”
Onboard sensing combined with data from vehicle-to-vehicle, vehicle-to-infrastructure and vehicle-to-everything technologies provided the information needed to predict driving environments and develop new technologies. The team achieved these benefits by developing the next generation in vehicle dynamic and powertrain control software, designed to proactively use “look-ahead” information to anticipate vehicle power demand.
The new tools developed to meet these efficiency goals include eco-routing, eco-driving and power-split optimization.
“We like to call eco-routing Google Maps with energy,” Rengarajan said.
Using a mapping tool like Google Maps, drivers can set their destinations and see routes that may add a couple of minutes to their arrival, but that are more fuel efficient. While the technology is appealing to the eco-minded consumer, for delivery and service fleets, this 5–10% savings in fuel consumption can add up to millions of dollars in savings each year.
Eco-driving uses information from neighboring vehicles to minimize accelerations, while power-split optimization uses knowledge of routes and speeds to optimize battery and engine operations to more efficiently meet power demands.
SwRI engineers used internal funding to deploy the eco-driving technology in a mobile driver advisory application, or “app,” that runs on regular smart phones or tablets. The driver advisory app connects with traffic lights and roadway infrastructure to “see” up to half a kilometer ahead and alert drivers to drive more efficiently. For example, if a stoplight is red a few blocks ahead, the app will tell the driver to speed up or slow down by a few miles per hour to avoid stopping. For heavy-duty trucks, making a full stop at a red light and re-engaging the engine when the light turns green is a significant source of fuel consumption.
The team also built a unique connected and automated vehicle (CAV) chassis dynamometer, a system to measure force, torque and power, that interfaces with traffic simulation software to provide a controllable, repeatable environment for testing the new technologies. Calibrated using real-world data from Fort Worth, Texas, the simulator proved critical for evaluating control algorithms and accurately quantifying energy consumption.
“Not only can these tools be applied to any on-road vehicle,” said Scott Hotz, assistant director of SwRI’s Ann Arbor Technical Center, “but we also believe there are more improvements to be made. It’s quite a leap from making efficiency improvements by modifying vehicles and engines directly.”
Following the program’s success, the SwRI team is collaborating with regulatory and commercial organizations to commercialize the new tools. Separately, the U.S. Department of Energy has provided $3.2 million to investigate the benefits of using CAV technology with different types of vehicles, as well as evaluating the impact of smart infrastructure solutions like intelligent intersections as part of the Energy Efficient Mobility Systems initiative.
Southwest Research Institute