NEW YORK—As regular readers of Cars Technica know, the auto industry is going full-speed ahead when it comes to self-driving cars. A number of OEMs and their technology company partners have promised us SAE "level 4" self-driving vehicles by 2021. But not all of these organizations are taking the same road to get there. Some, like Ford and Volvo, have decided to go straight to full autonomy by working on vehicles that won't need a human driver at all within specific geofenced areas (these are vehicles that you or I will use through ride-hailing services). Others, notably General Motors and Audi, believe in some degree of returning control to the human driver, who may or may not be giving the road their full attention. At this year's New York International Auto Show, the former group broke cover with its new Super Cruise system, which will be available on the Cadillac CT6 sedan later this year.

Are you paying attention?

To be accurate, unlike the system due to appear in Audi's next A8 flagship, Super Cruise is only a level 2, not level 3, autonomy. There are already plenty of level 2 autonomous systems on the market already, typically cars with a combination of adaptive cruise control—which maintains a car's speed to traffic ahead via the use of radar—and a lane keeping assist that reads the lane markers on the road with an optical sensor and steers to keep the car centered between them. But Super Cruise is closer to level 3 than pretty much every other level 2 system out there, since it combines adaptive cruise control and lane keeping with two notable advances that are going to play a large role in more autonomous cars in the future.

One of the big challenges with semi-autonomous driving is the need to return control to the human driver in cases where the computers can no longer handle a task. After all, how is a car supposed to know if its driver is paying attention? Currently, even the excellent semi-autonomous systems from Audi, Tesla, and Volvo all use the same trick; torque or touch sensors can tell whether the driver has their hands on the steering wheel. Go hands-free for too long—15 seconds in the case of Audi and Volvo, or several minutes for Tesla—and the car alerts the driver and deactivates the lane keeping assist.

That's because such systems are meant as driver assists, not driver replacements, although in their desire for longer hands-free cruising some Tesla drivers discovered they could spoof this by hanging weights off the steering wheel (that's not something we would condone or encourage. Low-speed traffic jam assists, on the other hand, don't have a time limit for hands-free operation, although they will only work when the car senses it is in heavy traffic.)

Head tracking

Jonathan Gitlin

Cadillac

Cadillac

The obvious answer to the problem is giving the car a way of detecting if its operator is actually paying attention. In this case, that's done via head tracking. Dubbed the "Driver Attention System," Cadillac's solution uses an infrared camera to track a driver's head position while Super Cruise is active.

Spend too long looking away from the road ahead, and the car will alert you that it's time to focus on the road. Alerts happen through a series of escalating alerts on the main instrument display, an LED bar set into the steering wheel, and even haptic rumbles from your seat. And since it's checking (and asking) for the driver to keep their eyes on the road, this system can't be spoofed like those Tesla ones. Though to note, you can satisfy Super Cruise warnings simply by returning your eyes to the road—no need to grab the wheel.

Ignore all of the car's alerts, and eventually it will bring the car to a controlled stop with the hazard lights on, alerting the emergency services through OnStar. And unlike Audi's forthcoming system, Super Cruise will stop the car in the lane it's in rather than navigating to the shoulder. That particular detail didn't go down very well with NHTSA, which wrote to Cadillac to express its concern. (Somewhat ironically, the NHTSA lawyer that signed that letter is now working for General Motors, according to Car and Driver.)

Geofencing

The second big improvement Super Cruise adds over extant level 2 systems is that it will only work on divided, limited-access highways. That's important, because it means Cadillac can feel safe offering the system with the peace of mind of knowing it won't be active in a situation outside the parameters for which its sensors have been optimized.

A good example of this are the optical sensors and machine vision algorithms that detect when a car ahead is rapidly slowing, automatically braking if necessary. Automatic emergency braking (AEB) is being added as standard equipment by car makers ahead of a possible mandate by the National Highway Traffic Safety Administration. But as we learned from NHTSA's investigation into a fatal Tesla Model S crash in Florida in May 2016, AEB systems are only designed to recognize a car from the rear—another vehicle crossing its path perpendicular to the direction of travel won't trigger a response.

Similarly, Cadillac has chosen to geofence Super Cruise. That sounds easy, but it's actually a rather monumental task. To that end, a fleet of Lidar-equipped mapping vehicles has been driving up the length and breadth of the US and Canada—more than 160,000 miles in total. Those vehicles have put together a high-resolution 3D map of the highway network, readable to the Super Cruise-equipped CT6. Coupled with the car's accurate GPS system, equipped vehicles know exactly where they are down to a couple of inches.

The CT6 pulls the map from Cadillac's servers (updated annually over the air). Though since it isn't equipped with a Lidar sensor itself, the car isn't able to upload fresh data itself; as a result the Lidar-mapping vehicles are still in service to cover roadworks and new building projects.

The map also lets the CT6 "see" much farther down the road than traditional optical and radar sensors allow, meaning it can adjust the engine, transmission, and suspension settings to cope with turns and so on.

Super Cruise should be available as an option on the Cadillac CT6 this fall.

Listing image by Jonathan Gitlin