Mercedes-Benz has developed the world’s first production car with what’s called SAE Level 3 driver assistance, and will deliver these vehicles to US customers later this year. Popular Science had the chance to ride along in a Mercedes EQS EV equipped with what the company calls Drive Pilot as it slogged through Los Angeles freeway traffic. The car’s ability to negotiate its way between trucks, give space to merging traffic ahead, and tolerate lane-splitting motorcycles that zoomed past was a marvel. A few years ago, optimists were predicting that by now we would all be getting chauffeured to our destinations by truly self-driving cars that appear when summoned and then drive off, either to park themselves, or, in the case of ride-sharing services, glide away to carry other customers. Reality has a way of intruding on such fantasies, as no less a fantasist than Elon Musk acknowledged in his tweet explaining Tesla’s failure to release the official version of that company’s Full Self Driving system. He said: “Generalized self-driving is a hard problem, as it requires solving a large part of real-world AI. Didn’t expect it to be so hard, but the difficulty is obvious in retrospect. Nothing has more degrees of freedom than reality.” One of the reasons for Tesla’s struggles is Musk’s decision to handicap his cars by expecting them to drive themselves using only cameras. Meanwhile, Mercedes-Benz’s philosophy is “The Best or Nothing,” and the difference in these approaches is illustrated by looking at the difference in the sensors used by the cars to drive themselves. Tesla uses cameras. Mercedes uses cameras, radar, lidar, GPS, ultrasonic, and a microphone. And autonomous vehicles from other companies typically use a combination of cameras, lidar, and radar. To understand why achieving Level 3 is significant, consider the Society of Automotive Engineers J3016 definition of the levels of driving automation. For Levels 0 – 2, the driver “must constantly supervise,” even if automated features are operating the car. Importantly, for Levels 3 – 5, it says that the driver is not driving if the features are engaged. Mercedes underscores this point by explaining that when Drive Pilot is engaged, the company has accepted legal liability for its actions. “[Level 3] is really a breakthrough leading into the space of Level 4,” Markus Schäfer, the chief technology officer responsible for development and purchasing at Mercedes-Benz AG, tells Popular Science immediately before the ride-along in the car. “[Level 3] is the main wall you’re hitting first. You have to break through in order to just advance to Level 4.” “You can do all kinds of things in level two,” he adds. “But the real interesting game starts when it comes to level three and four.” So how does the Mercedes system compare to other, similar options on the market? Its Drive Pilot’s Level 3 looks a lot like the Level 2 demonstrated by General Motors Super Cruise and Ford’s BlueCruise, with the difference being the change in responsibility from the driver in Level 2 to the machine in Level 3. So while the Level 2 systems enable hands-free driving only when the driver is watching the road ahead, Level 3 Drive Pilot frees the driver to respond to messages, play games, or watch videos. As with the Ford and GM systems, Drive Pilot operation is restricted to limited-access divided highways that have been meticulously mapped, and Mercedes says that its dual-receiver rooftop GPS can locate the car in its lane with a centimeter’s accuracy. The maps tell the car when, for example, there is an on-ramp ending in an adjacent lane, so that Drive Pilot will give cars that need to merge the space to do so. Ordinary traffic jam adaptive cruise control is rude by comparison, keeping a steady distance from the car ahead and leaving no space for cars to merge, so this is a welcome improvement. However, initially, Drive Pilot will be limited to speeds of 40 mph or below, making it only useful in heavy traffic situations and not for open-road cruising. That feature is expected to come with time, as safety regulators, Mercedes, and customers all become familiar with the technology. “We’re the first ones who want to just observe what’s going on and how the system performs,” says Schäfer. “Of course, very clear, our goal is to take it above [40 mph]. But once you have it to 40, it’s pure mathematics and technology sensor technology [to] increase speed.” The car cannot operate in Level 3 mode in fog or very wet conditions either, and Mercedes has installed a piezoelectric sensor in the front wheel wells that detects the splash of water from the front tires against a membrane to signal when the road is too wet for Drive Pilot. The cameras and microphone are trained to be on the lookout for emergency vehicles so that the EQS can pull aside to make room for them to pass. Training the algorithm to accurately discern the flash of emergency strobes and to ignore false positives was a substantial challenge according to a Mercedes engineer. This is why, unfortunately, Drive Pilot and other such systems are unlikely in the near future to do things that human drivers can do without thought: react to other cars’ brake lights and turn signals, he tells me. We can tell that Drive Pilot has taken over when the turquoise light atop the steering column and the two lights at the driver’s 10-and-2 positions on the steering wheel illuminate. The instrument panel provides a virtual view of the surrounding traffic, letting the driver know what the car sees. The day will likely come when we easily accept that the car sees everything it should, but for now this is important for instilling trust in the system by giving the driver the comfort of knowing that the car sees things that might be of concern. Drive Pilot puts on a credible impersonation of a human driver, albeit an infinitely patient one, when navigating L.A. traffic. It maintains a safe gap behind the car ahead and responds smoothly to the stop-and-go. When cars merge into the lane ahead, it doesn’t get panicky and slam on the brakes because its preferred following distance has been violated. Instead, it slows gradually to re-open a gap to the new car ahead. And check this out: you know that situation when the person in the left lane decides he needs to exit at the last minute and the car swoops from the lane to your left across three lanes to the exit, cutting you off in the process? As a human who can see the developing situation, you’ll normally just maintain speed or lift of the accelerator slightly to add some buffer space as the dive-bomber passes quickly through the lane. Computer drivers have historically lost their digital minds when this happens because suddenly there’s another car suddenly in the lane ahead. They can’t tell that the car will be gone from the lane as quickly as it appeared, so they think you are suddenly tailgating irresponsibly and they slow abruptly. But not Drive Pilot. The system’s radar can see the lateral velocity of the car passing through the lane so it knows that this is not an emergency, but is just a transient situation that will be over soon. So the EQS slows only slightly in response to this situation. And when traffic lightens and speeds exceed 40 mph or the car otherwise leaves Drive Pilot’s Operational Design Domain (that’s engineer-speed for the restrictions on the system), the car switches to Level 2 automation, which provides a similar driving experience but demands the driver’s attention and hands on the wheel. Over time, the Drive Pilot ODD will expand to include more roads, higher speeds, and worse weather. But that will take experience. “You have to be convinced about the safety and the degree of safety of your vehicle and that’s a result of a couple of million miles of testing,” Schäfer explains. “And of course, endless [computer] simulation.” Next stop: Level 4. Cars in this category will not need to hand over control back to the driver during the course of the drive and they may not need to even have a steering wheel or pedals. That will indeed require substantial customer confidence in the systems.
