What Is a Driver-Monitoring System?

A driver-monitoring system — sometimes called a driver state sensing (DSS) system — is an advanced safety feature that uses a camera mounted on the dashboard to track driver drowsiness or distraction, and to issue a warning or alert to get the driver’s attention back to the task of driving.

Driver-monitoring systems (DMS) are expected to become a standard feature in new cars as a result of regulatory and rating agency requirements. For example, the European Union has mandated DMS for inclusion in all new vehicle models starting in 2024, and the European New Car Assessment Program (Euro NCAP) currently grants a vehicle points toward a 5-star rating for including DMS.

How does it work?

Driver-monitoring systems typically use a driver-facing camera equipped with infrared light-emitting diodes (LEDs) or lasers so that it can “see” the driver’s face, even at night, and see the driver’s eyes even if the driver is wearing dark sunglasses. Advanced on-board software collects data points from the driver and creates an initial baseline of what the driver’s normal, attentive state looks like.

The software can then determine whether the driver is blinking more than usual, whether the eyes are narrowing or closing, and whether the head is tilting at an odd angle. It can also determine whether the driver is looking at the road ahead, and whether the driver is actually paying attention or just absent-mindedly staring.

If the system determines that the driver is distracted or drowsy, it could get the driver’s attention by issuing audio alerts, lighting up a visual indicator on the dashboard or vibrating the seat. If the interior sensors indicate that the driver is distracted while the vehicle’s external sensors determine it is about to have a collision, the system could automatically apply the brakes, using information from interior and exterior sensor fusion.

DMS and autonomous driving

Driver-monitoring systems are essential to autonomous driving at Levels 3 and 4, which require drivers to re-engage and prepare to control the vehicle at certain points along the trip.

The Society of Automotive Engineers (SAE) defines Level 3 as “conditional automation,” in which drivers are permitted to take their hands off the steering wheel but must keep their attention on the road in case they need to take control. Driver monitoring plays a critical role in making sure the driver is alert and attentive.

Driver-monitoring systems also have an important role to play in Level 2+ functionality to ensure the driver remains engaged, even when their hands are not on the wheel.

DMS and interior sensing

Driver-monitoring systems that can detect drowsiness or inattention are just the beginning. As these systems evolve, they will become part of a broad interior sensing platform that provides personalization, advanced safety, infotainment and even connectivity with smart home systems.

The DMS can identify the driver and enable personalization to automatically adjust the seat, temperature, side mirror, etc., to the driver’s preferences. The systems will be able to identify whether the driver is impaired or is having a medical emergency.

Drivers will be able to control functions with their eyes or with gestures. By adding a wide-angle camera where it has more visibility of the vehicle interior — such as near the rearview mirror — passengers can also benefit from increased functionality. For example, the camera can monitor both the driver and the cabin, which means it can detect whether a child has been left behind in a car seat, determine if an important object has been forgotten, or help personalize infotainment, HVAC or other in-cabin functionality.

All of these advanced features, and others that have not yet been conceived, start with the basic driver-monitoring system.