Dr. Zach Asher
KALAMAZOO, Mich.—While technology for autonomous vehicles has come a long way in the past few years, there are still steep hills to climb on the road to improving the reliability, safety and efficiency of self-driving electric vehicles. Dr. Zach Asher, assistant professor of mechanical and aerospace engineering and director of the Energy Efficient and Autonomous Vehicles Lab at Western Michigan University, has been working with a team of researchers across the country to address these challenges.
“With the hindsight of 10 years of highly funded development, we now know that software and cameras alone don’t provide an easy solution,” says Asher. “Perhaps a more patient approach, using infrastructure-based hardware in coordination with government transportation agencies, is the way to achieve zero-accident vehicles which actually use energy sustainably.”
WMU is teaming up with researchers from the Department of Energy’s Oak Ridge National Laboratory (ORNL) to drive solutions from outside the car— through sensors and processing embedded in road infrastructure. The team is placing low-powered sensors in the reflective raised pavement markers that are already used to help drivers identify lanes.
According to a paper titled “Development and Evaluation of Chip-Enabled Raised Pavement Markers for Lane Line Detection” in the journal IEEE Sensors with lead author Sachin Sharma, a doctoral student studying mechanical engineering at Western, and ORNL researcher Dr. Ali Ekti, microchips inside the markers transmit information to passing cars about the road shape. They are effective even when vehicle cameras or remote laser sensing called LiDAR are unreliable due to fog, snow, glare or other obstructions.
In addition to providing more accurate information about the driving environment, this technology shifts some of the processing load from the car’s software onto infrastructure—saving electric vehicle battery power and extending its range. Compared with a leading camera and LiDAR-based autonomous driving technology, the chip-enabled pavement markers can reduce navigational power consumption by up to 90%, the team reported in a technical paper titled “Vehicle Lateral Offset Estimation Using Infrastructure Information for Reduced Compute Load."
This project with ORNL is part of a larger project at Western, which is bringing together research and industry partners to develop related sensor and autonomous driving technologies such as radar retro-reflectors, high-definition mapping, computational offloading and weather sensing. WMU researchers are also using a vehicle driving on a closed course to measure the reduction in vehicle energy use enabled by these technologies, says Asher.
ORNL researchers experimented to find the best combination of transceiver, battery and antenna for the sensor package inside standard road markers, as well as those that are designed to handle snowplows. They then used a communications protocol that involves hopping across a particular radio frequency spectrum up to 50 times a second.
“It’s hard to detect, works well against interference, is low cost and doesn’t consume a lot of power,” says Ekti. Adjustments to the equipment could ensure its battery would last for the same replacement cycle as the pavement markers, typically a year.
“It’s amazing how far it can transmit—over hills, in snow. It’s a big deal,” says Asher. “Every step of the way, we’re surprised at how well this technology is working, and we’re finding some really cool ways it could be integrated.”
Researchers have enabled standard raised pavement markers to transmit GPS information that helps autonomous driving features function better in remote areas or in bad weather. Credit: Carlos Jones/ORNL, U.S. Department of Energy
ORNL researchers field-tested the sensor platform in a variety of weather conditions and in a remote national park in Montana with no wireless access. They found that it transmits more than five times beyond the original 100-meter goal. The sensors could also signal temporary lane shifts or closures in construction zones when high-definition maps might be out of date.
According to Ekti, marker sensors could also eventually convey information about temperature, humidity and traffic volume. The project team plans to work with students to build a smaller microchip for the markers as a substitute for more expensive off-the-shelf products.
Asher is planning road demonstrations for stakeholders including the Tennessee and Michigan departments of transportation, the Michigan Office of Future Mobility and the city of Chattanooga. These government agencies decide which technologies are implemented in infrastructure, so their involvement in the development process is critical, Asher says.
Read more about the work of the Energy Efficient and Autonomous Vehicles Lab.
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