After commenting on this question and realizing that the system is fairly complicated, I began to wonder how exactly Lane Keeping Assist works. While having service information does help some, it doesn't answer all the questions I had about the system or gave vague descriptions of the component functions.

So in short, how does Infiniti's version of Lane Keeping Assist work?

I'm more interested in the technical aspects of the system. If the steering input is converted to an electric signal, what's the process? How does the system know that the car is drifting out of it's lane? What sensors are involved? What modules are included in the system. Are there safety backups incase the EPS system goes down?

I don't care about the logic i.e. the math behind turning x input into y output.


2 Answers 2


Basic answer from infinitiusa.com on Lane Departure Prevention, but here it is:

LDP uses a camera to monitor the distance between the vehicle and lane markings and, if the vehicle drifts towards the lane markers, the system first sounds a audible warning, followed by a selective application of the brakes to help move your vehicle back into its lane.

However, Lane Keeping Assist takes this a step further. Not only does it make beeping noises, it is hooked up to the power steering such that at speeds above 45 mph, it will actually turn the steering up to a couple degrees if it detects that you are moving too close to the line on either side.

It does help keep you in your lane, but don't try it on the Autoban!

From wired.com:

Turning the steering wheel sends an electronic signal to the steering force actuator, which sends data to the electronic control unit, which forwards it to the steering angle actuator, which turns the wheels.

...then a bit later...

The system can adjust steering through electronic instead of mechanical inputs, which requires less work.

Here's a diagram of the basic setup of electric steering:

enter image description here

All that is left for the lane control system to do is to send an electronic signal to the electronic control unit which over-rides the manual input.

  • Can you expand on the electric power steering portion of the answer. while a general over view of the system is a good start, what i'm more interested in are the technical aspects of the system. like how the camera interacts with various sensors and how the control unit controls the steering.
    – Ben
    Commented Nov 3, 2016 at 22:59
  • @Ben, is this more what you were looking for?
    – anonymous2
    Commented Nov 3, 2016 at 23:07
  • @Ben, if you as far as the electrics are concerned, it's more of a programming question than a physical wiring question.
    – anonymous2
    Commented Nov 3, 2016 at 23:22
  • @anonymous2 Is there seriously not a physical connection anymore between the steering wheel and the wheels?? I would never buy a car that lacks that. You lose the feeling of the road, and imagine what happens when something fails in the system.. But then again, i'm a petrolhead, used to a 70s car of 1000kg with no power steering and little brake..
    – Bart
    Commented Nov 4, 2016 at 9:14
  • No, no one has yet made the jump to totally electric. There's a mechanical system running alongside, I believe. @Bart
    – anonymous2
    Commented Nov 4, 2016 at 10:15

According to this, it's just a camera looking for pavement markings. Getting closer to one sounds the alarm, getting too close selectively applies the brakes to steer the car back. I'm guessing the front brake of the side you want to steer towards will get applied.

  • 1
    I think he's talking about the Lane Keeping Assist, which actually takes this a step further.
    – anonymous2
    Commented Nov 3, 2016 at 22:56
  • Yeah, just read your answer. Am I the only one who drives a car that doesn't have a mind of it's own? :D
    – tlhIngan
    Commented Nov 3, 2016 at 23:14
  • Lol, I sympathise... :) Good answer all the same.
    – anonymous2
    Commented Nov 3, 2016 at 23:20

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