Autonomous vehicles might someday be able to navigate bustling city streets to deliver groceries, pizzas, and other packages without a human behind the wheel. But that doesn’t solve what Ford Motor CTO Ken Washington describes as the last 50-foot problem.

Ford and startup Agility Robotics are partnering in a research project that will test how two-legged robots and self-driving vehicles can work together to solve that curb-to-door problem. Agility’s Digit, a two-legged robot that has a lidar where its head should be, will be used in the project. The robot, which is capable of lifting 40 pounds, can ride along in a self-driving vehicle and be deployed when needed to delivery packages.

“We’re looking at the opportunity of autonomous vehicles through the lens of the consumer and we know from some early experimentation that there are challenges with the last 50 feet,” Washington told TechCrunch in a recent interview. Finding a solution could be an important differentiator for Ford’s commercial robotaxi service, which it plans to launch in 2021.