"In the back of my mind, I thought that drivers would probably put the automation on when the system was available and then disengage it when they got off the highway," said Pnina Gershon, a research scientist at MIT's Center for Transportation and Logistics AgeLab and the study's lead author. "That was my expectation. But it's surprising there's a high degree of collaboration between the driver and the system, even though it's hands-free driving."
The paper, "Driver Behavior and the Use of Automation in Real-World Driving," is perhaps the first of its kind to delve into how people are using driver-assist systems as their numbers grow. Super Cruise debuted on the Cadillac CT6 in late 2017 and is expected to be available on 22 GM vehicles by 2023.
While there is ample anecdotal evidence of how a handful of drivers misuse driver-assist systems — check out the YouTube videos of Tesla drivers sitting in the rear seats while Autopilot operates — there is not much that details how drivers properly use the systems in everyday situations.
Gershon cautions that the paper relates to Super Cruise specifically. Extrapolating the results to other assistive systems would be difficult because of system differences. GM, for example, uses an inward-facing camera to monitor driver behavior, and Super Cruise will disengage if drivers don't keep their eyes on the road. Parallel studies involving other systems are underway at MIT.
Researchers had 14 participants drive CT6 models for one month each. The cars were equipped with cameras so researchers could view driving behaviors and traffic environments across more than 22,000 miles of driving and monitor disengagements and "transfers of control." They counted 5,343 of these transfers in 1,690 trips, though not all occurred with Super Cruise or adaptive-cruise use.
System-initiated disengagements that resulted in a handoff to human drivers accounted for less than 1 percent of the observed control transfers. Researchers categorized the remaining human-initiated transfers into strategic, maneuver and control categories.
- Strategic might be instances in which humans took active control for long stretches, such as to prepare for an eventual exit from the highway.
- Maneuvers might be passing a vehicle ahead to maintain a set speed.
- Control would account for making adjustments in response to other drivers.
Such classifications can help engineers and policymakers consider how to set performance benchmarks for assistive-driving systems.