Ford wants to keep drivers alert on the long road to autonomous cars

Instead of building fully autonomous cars, Ford plans to gradually add more technology to help drivers. Examples available now include automatic parallel parking and "lane assist," which detects if the car is leaving its lane and alerts the driver through sound or vibration. Like other carmakers, Ford also offers adaptive cruise control that prevents getting too close to the car ahead, and forward collision warning.

Future automated features may involve "crowdsourcing" data from many cars in the same area. For example, if one car's wheels slip in snow or ice on a stretch of road, it could share that information so other vehicles could automatically adjust for the conditions, Butler said.

But moving gradually to cars that drive themselves raises another issue: How to make drivers pay attention when they have less to do.

Ford's exploring that problem, Butler said. As features such as lane assist and auto-parking are added, the company is trying to make sure drivers understand their limitations. And Ford is looking at issues such as cognitive load, or the number of tasks a driver's brain can deal with at one time.

An early example of making sure drivers are paying attention is drowsiness detection, Butler said. Lane-assist is its own form of drowsiness detection, using the driving itself to determine whether a motorist is dozing off. The auto industry is developing other techniques, including in-car cameras that watch the driver's eyelids and seatbelts that sense breathing and heart rates.