How ADAS Works in the Winter
With winter getting uncomfortably close, let’s grab a hot beverage and examine a topic that is sure to cause headaches this season: ADAS–equipped vehicles and winter driving.
ADAS and Winter
ADAS is short for “Advanced Driver Assistance System.” Each manufacturer has its own name for the suite of functions that make up its ADAS. Honda calls it “Honda Sensing,” Cadillac calls it “Super Cruise,” and Tesla, “Autopilot.” Essentially, ADAS covers a whole slew of system operations that make a car capable of performing a set of functions by itself, or without a human doing 100% of the operation. There is a spectrum of functions, ranging from a simple warning when someone is in your blind spot, to literally steering and braking for you. These systems are finicky at best and have operational quirks even in ideal conditions. Let’s talk a bit about ADAS and some considerations when using (or attempting to use) it in the winter.
Since I am a Honda man, I am going to focus on the Honda Sensing suite. It’s a pretty good system with basic nuts and bolts that you can use to try to intuit operation on other vehicles. One of the biggest hurdles in these systems is decoding the long list of acronyms. Here are a few:
The Honda Sensing Suite
Forward Collision Warning is FCW, Lane Departure Warning is LDW, Lane Keeping Assist is LKAS, Blind Spot Information is BCM, etc. Honda keeps it pretty clean with their acronyms and the function is relatively intuitive. Take Collision Mitigating Braking system, for example, it sounds like it will warn you of an impending collision and possibly apply the brakes for you if there is no intervention. This is indeed what the system does. Lane Keeping Assist sounds like it might steer the vehicle back into your lane when you wander out of it, and that is indeed what it does.
Most of these systems are made possible due to two new hardware. There is a camera mounted in the windshield and a millimeter-wave radar mounted behind the front grille.
These two components work in tandem with the traction control and electric power steering systems to monitor and warn if necessary, making driving a car a more mindless experience.
To put it generically, radar is used for detecting solid objects whether they are in motion, standing still, or in a non-linear trajectory in comparison with the vehicle’s own. The camera also detects objects, but besides solid objects, it detects lane markings and speed limit signs. If either of these two components come up with the calculation that you are drifting in your lane or coming up hot on a car or pedestrian, they initiate the traction control system and/or power steering system to intervene.
Lane control uses the front camera only, as it must detect road markings that the radar cannot see.
Lane Assist and Auto Braking
I can tell you that the LKAS’s (Lane Keeping Assist) opinion of what being “in my lane” means, and my opinion, sometimes differ significantly. I will notice the warning chime, and the nudge of the wheel regularly when I feel like I am being attentive and aware of my lane position. The LKAS, when allowed to have its druthers, likes to wander from line to line, picking which one it can see the best.
I will also say that the CMBS (Collison Mitigating Brakes) can sometimes choose to sound the alarm when I am coming to a very reasonable stop—on the flip side, it can be radio silent when I am coming up fast on someone’s bumper. I never forced it to activate when I was doing pre-delivery inspections at the dealer, but I get it to activate from time to time during normal driving.
This is a learning system, and it will get a bit better as it learns a driving style, but even under ideal conditions, there are glitches and hiccups in operation. So, what happens when snow is covering the road? When salt is packed up on the radar? Does this system stand a chance of operating well on an icy road with unclear markings? I don’t know how many of you have driven in a blizzard, but you can hardly see anything, let alone which lane you’re in.
ADAS System Caveats and Glitches
Honda and every other OE have a long list of system caveats for weather and road conditions. Consult with the manual for all the details, but usually, the list goes a bit like this.
- Driving in bad weather (rain, fog, snow, etc.)
- Sudden changes between light and dark, such as an entrance or exit of a tunnel
- There is little contrast between objects and the background
- Driving into low sunlight (e.g. at dawn or dusk)
- Strong light is reflected onto the roadway
- Driving in the shadow of buildings, trees, etc.
- Roadway objects or structures are misinterpreted as vehicles and pedestrians
- Reflections on the interior of the windshield
- Driving at night or in a dark condition such as a tunnel
- Driving on a snowy or wet roadway (obscured lane markings, vehicle tracks, reflected lights, road spray, high contrast)
- The road is hilly, or the vehicle is approaching the crest of a hill
- Driving on a curvy, winding, or undulating road
- Headlight lenses are dirty, or headlights are not properly adjusted
- The outside of the windshield is blocked by dirt, mud, leaves, wet snow, etc.
- The inside of the windshield is fogged
- An abnormal tire or wheel condition (wrong-sized, varied size or construction, improperly inflated, compact spare tire, etc.)
- When tire chains are installed
- The vehicle is tilted due to a heavy load or suspension modification
- The camera temperature gets too high
- Driving with the parking brake applied
- When the radar sensor in the front grille gets dirty
If any of the conditions for the road and vehicle are on the list, you can expect erratic or possibly no function from part of, or all the ADAS system. This is just the list from the CMBS section of the owner’s manual and does not include pedestrian notes. Tesla even warns you about kangaroos. The point is to show how limited these systems still are—they may seem like miraculous bits of hardware and software, but they are still far from perfect.
These are some of the conditions involving just road markings on clean roads that you may have LKAS malfunction.
Quick ADAS Fixes
Some vehicles will literally tell you to go clean off the radar area of the front grille. This happens very frequently and you may have to stop and do this several times on a single drive in some cases. So when a customer comes in complaining about operation during the snowy months, make sure to educate them. Wipe off the windshield and the front grille, and advise they wait until the roads are clear and dry before they try to engage ADAS on their commute. Better advice yet would be to retire the systems between November and March and break them out again the same time you dust off the lawnmower.
And if want to talk me to about any Honda in your shop, I’m available to call as part of our Virtual Tech team – 1.800.288.6210
All images courtesy of Honda