More than four months after retiring as Ford Motor Co.’s automotive president, Joe Hinrichs has resurfaced on the board of a company pioneering a unique sensor for autonomous vehicles.

Hinrichs, 53, has joined the board of directors at WaveSense, of Boston, a startup that uses ground-penetrating radar to help self-driving vehicles better understand and navigate road environments.

“WaveSense is delivering the most precise and reliable vehicle positioning system at a cost that allows broad adoption,” Hinrichs said in a statement. “Knowing where you are is fundamental to enabling the next-generation safety and performance features the automotive industry is looking for.”

Two other veteran automotive executives are joining the startup’s efforts to bolster its industry chops as it turns toward commercialization. Former General Motors CFO Chuck Stevens and former Continental Chief Technology Officer Kurt Lehmann have been appointed to WaveSense’s advisory board.

“Joe, Chuck and Kurt are world-class leaders in the automotive industry, and they will be invaluable assets as WaveSense navigates customer partnering and scale-up,” WaveSense CEO Tarik Bolat said. “Their guidance will help us move faster and smarter, and we’re thrilled to have them as part of the team.”

WaveSense takes a fundamentally different approach to using radar than other companies working on sensors for self-driving vehicles. Instead of trying to re-create perceptions of what a human driver might see, the company’s technology utilizes ground-penetrating radar to see through a road and create a map of the subsurface.

By sending radio waves 10 feet below the road, the system can receive unique reflections based on soil types, soil density, roots, rocks, utility infrastructure and more. The result is something akin to a subterranean fingerprint that allows vehicles to localize themselves to within 2 centimeters of a precise location.

“Sometimes you are driving down a highway, and there’s not a lot of signs or trees to look at, and that can make localization hard,” Bolat said during an appearance on the Shift mobility podcast last October. “Whereas looking into the ground, you always have something to look at.”

Ground-penetrating radar has been used for military purposes and in archaeology and utility pipeline work, but WaveSense, spun from the Lincoln Lab at the Massachusetts Institute of Technology, is the first company using it for automotive applications.

Hinrichs spent 19 years at Ford before an abrupt retirement, effective March 1, that followed the company’s disappointing fourth-quarter earnings. He had overseen all of Ford’s and Lincoln’s global automotive business.