Nissan Motor Company
In the blizzard of recent opinion pieces concerning new introductions of automated driving features in mass market automobiles, a few mis-understandings have started to float around that I will address here, hoping they don’t propagate further.
Last month Nissan’s ProPilot 2.0 was announced for the Japanese market only. Initially available on the upscale Skyline model, there are ground-breaking features such as automatically negotiating freeway-to-freeway interchanges. Very impressive stuff and I’ve been prodding my Nissan colleagues to accelerate North American introduction! But of course they remind me that adapting a complex system to another region with different traffic dynamics and road rules is quite an involved process and must be done carefully. All vehicle manufacturers take this approach when introducing driver assist systems in disparate markets, but I’m nevertheless impatient.
A recent article unfortunately characterized ProPilot 2.0 as an SAE Level 3 system. Others have referenced this article such that this carefully designed Level 2 system is now being wrongly framed. Let’s nip this in the bud.
As a start, a review of the capabilities implemented by Nissan in ProPilot 2.0 are in order. The Nissan system evokes the Cadillac SuperCruise™ system introduced in 2017, which controls steering, braking, and throttle while on an approved highway, as long as the driver is continuously monitoring the driving environment. GM added a driver monitoring system which is key to allowing hands-off capability, providing some degree of confidence that the system is being used responsibly. ProPilot 2.0 goes one step further with “navigated driving,” providing ramp-to-ramp highway driving based on a route entered into the navigation system by the driver. The system supports hands-off driving while cruising in a single lane; when a lane change is needed, the driver is prompted to place their hands on the wheel and press a button to approve the maneuver, what I call a “supervised lane change.” The system then safely controls steering, brakes, and throttle to perform the maneuver based on data from sensors that can see in all directions. For the freeway-to-freeway interchange feature noted above, ProPilot 2.0 handles a lane branching in two directions, based on the designated route.
Nissan stresses that the driver must remain attentive and be prepared “to immediately take manual control of the steering wheel when conditions of the road, traffic, and vehicle require it.” Similar to SuperCruise, lack of response by the driver will cause the vehicle to activate hazard lights and come to a graceful stop, opening an audio connection with an emergency call center.
The article cites driver monitoring as a reason to dub this a Level 3 feature, but the presence of a driver monitoring system does not trigger an uptick in automation level. Of the six SAE levels, the distinctions between Level 2 and Level 3 are the most difficult to parse out without diving deeply into the SAE J3016 standard itself, rather than referring to their helpful but more general summary charts.
For both Level 2 and Level 3, the driver support system is providing “sustained lateral and longitudinal vehicle motion control.” The “sustained control” of steering is a bit of a murky point. Different systems will handle different degrees of road curvatures and react in particular ways to lane markings for at freeway exits. Some are intended for highway use and will not activate at lower speeds. SAE 3016 is a definitions document, not a performance document. It succeeds in providing a manner to talk about automated driving but having a “Level X” system on your car does not tell you what its limits are. Only the manufacturer can tell you this.
The defining difference between Level 2 and Level 3 comes with OEDR, or “Object and Event Detection and Response.” OEDR is the geek term for doing what any driver does: keep an eye on any factors that might affect driving, especially safety, and deal with it (a core aspect of the “Dynamic Driving Task”). OEDR is defined in detail in the standard. Table 1 in SAE J3016 states that for Level 2, “the driver completes the OEDR subtask and supervises the driving automation system,” immediately taking control when conditions warrant. For Level 3, OEDR is handled by the Automated Driving System (ADS); the driver retains responsibility to be “receptive to ADS-issued requests to intervene.” The flow chart below from SAE J3016 is a great way to negotiate the “levels maze.”
SAE J3016 Simplified Logic Flow Diagram for Assigning Driving Automation Level to a Feature (Figure 9)
SAE International, SAE J3016™ JUN2018
In a Level 3 system, the system is handling OEDR and the person in the driver’s seat need not provide continuous attention to the road. But ProPilot 2.0 requires the human driver to stay alert and keep their eyes on the road (as confirmed by driver monitoring), clearly assigning the OEDR task to the driver. Based on Nissan’s information, there’s no doubt that ProPilot 2.0 is a Level 2 system. I am confident that my colleagues in the SAE On Road Automated Driving Committee, the group that produced and continues to update J3016, will agree here.
Audi and BMW offer their own forms of Level 2 systems and I’m expecting more to be announced in the next year. Its important to get the distinctions right and understand that the driver is still very much in the game.
Anyone driving a Level 2 system would naturally prefer to do other things with their hands, eyes, and brains than drive. This is the promise of Level 3 systems, but no Level 3 cars are available for purchase at this time from your friendly neighborhood car dealer. Level 3 systems are certainly on the way, such as the 2020 Mercedes S-Class and the BMW 2021 iNext. There are some interesting new wrinkles that come with Level 3 which I’ll address soon.
