IIHS Find Flaws With Adaptive Cruise Control, Lane Keeping Assist Systems

author: Vineeth Joel Patel   

Before coming out with fully-autonomous vehicles, automakers are steadfastly working on perfecting the semi-autonomous technology they have on the road at the moment. Modern safety features, like adaptive cruise control, lane keeping assist, blind spot monitoring, and automatic emergency braking are making cars safer than ever, as they lend a helping hand to drivers. 

Unfortunately, some drivers have abused the systems, testing their limits on public roads and putting peoples' lives in jeopardy. This has led to fatal accidents and accidents where human drivers and autonomous systems are trying to find a way to cohabitate. While the systems are better than before, they're not perfect. And that's something the Insurance Institute for Highway Safety (IIHS), revealed in its latest study. 

In a paper called "Reality Check," the IIHS issued a warning to drivers, stating that semi-autonomous systems didn't handle driving tasks as humans did and ran into problems. 

Putting Level 2 Autonomy To The Test

For its testing, the IIHS got behind the wheel of a few vehicles with Level 2 autonomy. According to SAE International's scale, Level 2 is considered partial automation. That means the vehicle can steer, accelerate, and brake under certain conditions. The majority of driving, including changing lanes and responding to traffic lights, though, falls under the driver's responsibility. 

The cars included the 2017 BMW 5-Series with "Driving Assistant Plus," 2017 Mercedes-Benz E-Class with "Drive Pilot," 2018 Tesla Model 3 and 2016 Model S with "Autopilot," and 2018 Volvo S90 with "Pilot Assist." As the institute points out, all of the vehicles were found to have a rating of "Superior" for their automatic emergency braking systems. 

The IIHS found that the systems were capable of saving a drivers' life in an emergency situation, but they were also prone to fail under various circumstances.  "We have found situations where the vehicles under semi-automated control may do things that can put you and your passengers at risk, and so you really need to be on top of it to prevent that from happening," David Zuby, the institute's chief research officer, said reports the Associated Press. 

How Did Adaptive Cruise Control Do? 

To test the vehicles' adaptive cruise control systems, the IIHS put all of the cars through four tests. The first one involved getting up to a speed of 31 mph toward a stationary vehicle. Adaptive cruise control was turned off for the first test. Of the five vehicles, only two hit the object – both of the Teslas. 

After getting a baseline on how the cars' autobrake systems worked, the IIHS repeated the same test with adaptive cruise control turned on. The institute also switched between the systems' close, middle, and far setting in multiple trials. 

With adaptive cruise control on, the 5-Series, E-Class, Model 3, and Model S all avoided the target, with the institute stating that the vehicles "braked earlier and gentler than with emergency braking." All of the aforementioned vehicles braked in a similar manner in spite of the different distance settings. The Teslas, interestingly, braked earlier than the 5-Series or the E-Class. The S90 braked just as forcefully as it did when adaptive cruise control was turned off. 

A third test was conducted and saw the cars follow a lead vehicle that came to a stop and then accelerated. All of the vehicles passed this test without an issue. 

The fourth test saw the vehicles follow a lead car and switch lanes. After switching lanes, the vehicles' systems would have to pick up a stationary inflatable object. All of the vehicles picked up the object and avoided an accident. Just as before, the S90 braked later and more forcefully than the other cars. 

While the track tests, for the most part, revealed that the cars' systems all performed well, the IIHS took the test to the road to see how things worked in the real world. The road tests showed another side of the cars. "Out on the road, engineers noted instances in which each vehicle except the Model 3 failed to respond to stopped vehicles ahead," claims the institute.

The IIHS' testers and engineers found instances where cars briefly detected a stopped vehicle and then lost it the next second, forcing the driver to take immediate action. At other times, the cars braked unnecessarily and too cautiously. "ACC systems require drivers to pay attention to what the vehicle is doing at all times and be ready to brake manually," said Jessica Jermakian, IIHS senior research engineer. 

As the institute points out, the Model 3 was one of the more noteworthy vehicles when it came to unnecessary braking. The study claims that the vehicle unexpectedly braked 12 times, seven of which happened because of tree shadows that were cast on the road. Other times the vehicle decided to brake unexpectedly happened when a car, well ahead on the road, in another lane crossed into the vehicle's path. 

"The braking events we observed didn't create unsafe conditions because the decelerations were mild and short enough that the vehicle didn't slow too much," said Jermakian. "However, unnecessary braking could pose crash risks in heavy traffic, especially if it's more forceful." 

What About Lane Keeping Assist? 

To test the vehicles' active lane-keeping assist systems, the IIHS conducted two tests on open roads with no other vehicles in sight. All five cars had systems that provided steering assistance that centered the car when driving on clearly-marked lanes. The cars, as the institute pointed out, may use a lead vehicle as a guide. 

The IIHS also tested the active lane-keeping systems on curves that saw the cars tackle three different sections of road through six trials. Of all the vehicles, only the Model 3 stayed within the lanes for all of the 18 tests. The Model S performed similarly, but overcorrected on one turn, causing it to cross the inside line. 

The 5-Series performed the worst in the test, as the BMW stayed within its lane in only three of the 16 trials. Other cars, like the E-Class and S90, stayed in their lane nine out of the 17 tests. 

Hills, as the institute found, seemed to flummox the systems. The IIHS believes that the crests of a hill obscures the lane markers on the road, which makes it difficult for the vehicles to know where they are on the road. On the hills, the E-Class performed the best, staying in its lane in 15 of the 18 tests. The 5-Series, Model S, and S90 struggled, with the 5-Series struggling the most, failing to stay in its lane on 14 tests. 

The tests reveal that automakers and tech companies are at a crossroads when it comes to current semi-autonomous systems. "Designers are struggling with trade-offs inherent in automated assistance," said David Zuby, IIHS chief research officer. "If they limit functionality to keep drivers engaged, they risk a backlash that the systems are too rudimentary. If the systems seem too capable, then drivers may not give them the attention required to use them safely." 

Vineeth Joel Patel

Joel Patel has been covering all aspects of the automotive industry for four years as an editor and freelance writer for various websites. When it comes to cars, he enjoys covering the merger between technology and cars. In his spare time, Joel likes to watch baseball, work on his car, and try new foods