RDM vs LKAS

Lane keep assist actually keeps the car centered in the lane preventing fatigue on long interstate runs. It is more of a driver assist feature to keep you on the straight and narrow, nearly like auto pilot.

But Road departure mitigation is more of a true safety feature as it doesn’t keep it fully centered, and allows much more deviation within the lane, but will still react to help keep you from drifting off the road into oncoming traffic or into a guardrail, if it actually sees the car crossing one of the side lines...like if you drift off or simply aren’t paying attention it might save your bacon...

 

No, LKAS keeps you fully centered so RDM will never need to activate because the car won’t cross a line. Obviously you still need to drive the car in all modes. I recommend you try both modes while on a long interstate drive with wide shoulders in light traffic so you can feel the difference. Take hand almost off the wheel (just keep a very light touch so you can feel how it shakes the wheel to wake you up) and see how it reacts in each mode as the car drifts toward a line. Then youll understand it better.

 

You need to be going only 45 mph to have RDM perform its bacon-saving magic.

 

Interesting discussion. I've seen a lot of videos (including one or two for the Clarity) where the reviewer is saying how pathetic the Lane Keep Assist is. In those videos, they say the system does not keep the car centered at all. I wonder if they're just depending on the RDM. I found Clarity's LKAS to work well but I've been too chicken to trust it on curves.

 

Indeed it is NOT intuitive to turn Hondas LKAS on, and default on these cars is always OFF. The LKAS system cancels every single time you shut the car off. Gotta have the 2 solid lines showing on the icon in the upper right corner of the screen to work. If they're not visible and solid, the system is off and isn't working. Honda is a bit different than most, and if the reviewers don't even know how to turn it on, they were likely not using the system. With my job I have been a high mileage driver (60K per year, lots of interstate) This is my 2nd Honda with Sensing package, and both have worked very well in most conditions. Understand that rain, faded lines, multiple "eyebrows/deceleration" lanes, frequent lane changes, driving too close to 45 mph, etc can screw it up. But with clearly visible lines once the car is in the lane, it holds extremely well and you only need to have a hand resting on the steering wheel loosely for hundreds of miles at a stretch, and it will hold you centered and true without one single steering wheel correction. Long high speed interstate trips are where the system excels, and that's really what it's designed for. ESPECIALLY on an extremely windy day with cross winds! Passing semi trucks running at 75 mph in a 30 mph cross wind! This is where it's truly priceless...any Honda with sensing, WITH SYSTEM PROPERLY TURNED ON, will do EVERYTHING for you, and you just keep a finger on the steering wheel. On 2 lane highways it can be a little quirky but once you practice with it you'll learn to know what to expect of it. I believe those who rarely use it for long road trips (like most Clarity owners who are just banging around town??) will rarely see the benefit of the system, and these people will have a harder time getting past the slight learning curve to understand how it really works, and when it's appropriate to turn the system on and/or off.

 

Remember that the steering strength of LKAS is limited. If you're going fast, it will not keep you in the lane on a tight curve where you would have to turn the wheel more than a few degrees, like on 55 mph twisty rural farm roads.

It's awesome on highways, though. Between LKAS and ACC, interstate trips are ridiculously lacking in driving fatigue and stress compared to my old no-assistance vehicle

Also don't be one of those silly people who obliviously rides for miles with their blinker on. The lane keeping systems don't function (as they shouldn't) when it thinks you're intending to change lanes.

 

Ditto on all the above about LKAS and RDM. I didn’t see it mentioned, but to me the most important safety aspect of RDM is that it will brake if you run off the road (as in asleep at the wheel or incapacitated). I also appreciate the warning wheel shake and consider it my guardian angel NOT my self driving car.

 

I was driving with LKAS on and functioning and the RDM activated, which made me laugh because it was essentially criticizing its own driving.

 

I often chuckle when using LKAS with my hands off the steering wheel. On a slight curve the LKAS will drift over to the edge of the lane and the RDM will complain. I might say out loud, "You did it now me!"

 

I've watched the LKAS on a straight road and it slightly wanders back and forth. It's not smart at all about passing by an offramp and doesn't know what to do. But all in all I like it and use it quite a bit. Even on curvy roads where it has insufficient power to turn the steering to meet the curves it still assists. It makes all driving over 45 mph easier. I really wish it would not time-out and demand my hands on the wheel when the road is straight as an arrow. I have found that I can just rest my hand near the bottom of the wheel and there is just enough torque for the car to think I'm steering though.

Taking long trips in this car is much less fatiguing.

 

It is LKAS which works between 45 and 90 mph. RDM starts working at 32 mph.

 

Those are the LKAS markers, they have to be thick white like that to be active, when inactive they look more like this:



Similar to how the ACC will have solid white and fill in the car when its active and dashed when inactive (as seen above).

You have to active it every time and it only works above 40-45 MPH.

That said, it works very well and even takes slight turns by itself well. It does not like the lane splitting or left hand turns and such, which is why it requires you to keep your hands on the wheels (most) of the time. like jd said I keep my hand just slightly on it to make it not get mad at me and it does handle very well by itself most of the time.

Edit:

Here are the official details on it:

 

IME it prioritizes the right-hand lane marking too much. If I'm in the right lane, it will invariably pull towards every exit, but in the left lane on a divided highway, it does just fine ignoring the crossings and their entry lanes. Would be interesting to be able to configure that, to switch between left- and right-hand lane markers depending on which lane I'm traveling in.

 

Amen brother. I feel exactly the same way about LKAS and RDM and ACC. All of these are SAFTEY features and not a poor man's Self-Driving car! For that you'll need several more cameras and radars and computing power and double the price!

 

Not to sound like a rant, but here is my take on it. When the lane keeping assistant light is on in my Clarity, it is not the Clarity that is doing the role of assistant, it is me!!! What a joke! This thing only works well when there is a grand conjunction of the planets! The lines must have reasonably high contrast for it to lock on, and in Texas, that is not at all the norm.

Now the danger is that if I look away for more than about 5 seconds, I often find that the car is drifting well off center and if I don't assist, I get the warning light.

And forget most curves that are more than very gentle. I went across lines two dozen times in my trip between Austin and Houston.

Also, did I mention I live in Texas? Coming from Baton Rouge to Houston, I had a strong cross wind (maybe 15 mph) and the weak Bass steering motor did not have enough torque to keep the car between the lines from the wind pressure on the front end!

What a joke. Yeah, works on a good day with a straight road with good marking, but even here, I don't trust it.

ACC is much better, but has a tendency to heavily brake sometimes when traffic ahead slows even a little. Mostly it is OK, but the lane keeping assistant is (in my own opinion) un-trustworthy if there is wind, less than pretty straight road, and good markings, and where I live, I most typically have at least one of these three conditions, and often two and three.

It is pretty horrible I think. Steering motor needs more torque. At least that would deal with two of the three issues.

 

Maybe your windshield is very dirty over the camera. Clean it. There are some atrocious roads near Austin and Round Rock that have been scraped up by people dragging chains or broken trailers along the pavement and areas that have been restriped multiple times with the previous layer of stripes not completely removed, and my Clarity navigates them just fine. It also does just fine on several two-lane roads where there's just a stripe in the middle and a curb on the side.

It's supposed to be weak, so in case it pulls the wrong way, the driver won't have trouble clobbering it. I've used it around Austin and I've used it on interstate trips, and it makes the drive much less stressful. It's not supposed to steer for you. It's only meant to keep the car centered in the lane. The side-effect of steering for you in some circumstances is a bonus. It definitely won't do that if you're going 60 mph around a curve where you'd have to turn the wheel more than a few degrees.

Turn the follow distance to the minimum so that it can't do the fall-back-catch-up-fall-back-catch-up thing.

 

I've tried openpilot ( https://comma.ai ) on mines and it seems to do a better job of ACC and LKAS. Keep in mind this is alpha/beta quality aftermarket system. Heres a similar installation video