ADAS calibration is necessary after many types of automotive repairs. ADAS stands for Advanced Driver Assistance Systems. Currently (2022) virtually all new cars have some type of ADAS system, but some 10 year old cars also have early ADAS systems. If you’ve found the article, you may have been told that you’ll need a camera calibration after a windshield replacement. Or maybe somebody said you needed a radar calibration after cooling system or air conditioning work. Like most people, you might wonder if it’s really necessary. In this article we’ll discuss the various types of sensors used in ADAS systems and which calibrations are needed.
Calibration after windshield replacement
We only repair Toyota, Subaru, Honda, and Mazda. Subaru was the first brand to add stereo forward facing cameras behind the windshield near the rearview mirror which they branded “EyeSight”. The two cameras provide depth perception which can be used to gauge distance and relative position, similar to human eyes. The system arrived in the US almost 10 years ago now so there are a lot of vehicles on the road sporting this technology.
The cameras look through the windshield, so the glass is important. Variations in glass thickness and impurities can distort the image and block light. The cameras don’t like this. Since glass quality is important, Subaru requires genuine Subaru windshields. We don’t replace windshields here, as a result we haven’t seen issues first hand. However, we’ve heard many stories from reliable sources. It’s a real problem. If you have a Subaru, buy a Subaru windshield. If your insurance company says no, show them Subaru’s position statement. They’d be crazy insist on a non-OE-approved repair on a safety system.
Is calibration really needed after a windshield replacement?
Do you really need to calibrate the system after a windshield replacement? What if you’re sure the camera wasn’t bumped? The real answer is that I don’t know. I’m not an engineer and I wasn’t involved with the design or testing of the system. So, in absence of knowledge to the contrary, I’d strongly recommend following the OE’s recommendation. You may know that eyeglasses distort our view of the world, but our brain quickly compensates and we can no longer see the distortion. The calibration is resetting the system’s brain to work with its new glass.
What is an EyeSight calibration
Calibration is both simple and complex. An explanation that makes it sound simple is: “Put a target in front of the car at a specified location, then connect the Subaru Select Monitor 4 (SSM4) to the car and run the calibration routine”. However, in reality the devil is in the details. And oh boy, there are a lot of details. Chief among them is accurately placing the target. The target should be within 4mm of the centerline as well as the distance and height specified. The Americans among you may wonder how big is 4mm. Around the width of these square brackets on your screen — [ ]. It’s not a whole lot of wiggle room.
While the poster on the whiteboard certainly looks low-tech, this is actually the Subaru-approved tool. They even have instructions to turn the whiteboard around so the pen tray doesn’t interfere with the plumb bob used for centering.
Subaru has procedures for setting the “random” target using nothing but tape measures, string, and a plumb bob. This will work, but it takes a lot of time. 3-axis laser levels make this ADAS calibration a whole lot quicker to set up.
Radar Calibration
Most new cars have a radar sensor behind the front bumper, often under the emblem. Whenever the bumper is removed, the sensor must be calibrated. The bumper is removed during many types of repair, not just for body repair. The bumper often blocks access to the headlights, radiator, and condenser.
Radar calibration is similar to camera calibration. A target is placed at a set point in front of the car and then we use a scanner to run the calibration routine. Instead of a target that looks like a crazy QR code we use a radar reflector. A radar reflector is a trihedral (a three sided hollow pyramid).
Are aftermarket ADAS calibration systems OK?
I don’t have the answer. This isn’t really my field, so much like using only Subaru windshields, I’m going to follow the manufacturer laid out as closely as I can. When we ordered the Toyota trihedral I was very disappointed. It has a flimsy wobbly stand and the mount and trihedral are also flimsy. Many people had told me the Autel reflector was better, so I bought one. But here’s the thing: it’s not the same size. And while the stand it much better, the box the target mounts to is thin junk.
So, does size matter? Once again, I don’t really know, but it seems like it would. If studying bouncing radio beams is your thing, please drop me a line and let me know.
I’m no engineer, but I was curious so I did a little research on the interwebs. I probably got a lot of things wrong. Here’s what I think I know. (And here’s where I got it)
Trihedrals amplify the returning radar signals in a predictable way so they are used for radar calibration. The amount it reflects back is known as its radar cross-section (RCS). The RCS for a trihedral can be calculated using the formula above on the right. As near as I can tell, automotive radar wavelength is likely around 4-5mm. I measured the Toyota target and the Autel target and did my best to plug the numbers into a calculator (I’m also no mathematician). To me it looks like that the Autel is bigger in both physical size and RCS (by what seems like a lot). Does it matter? I don’t know, so I use the wobbly target we ordered from Toyota.
Lane Departure Warning
Another ADAS calibration is for lane departure warning. This system has two radar sensors on both sides of the car near the rear bumper. This calibration uses the same radar reflector are requires the target be repositioned during the calibration.
Wheel Alignment
All ADAS calibrations begin with a wheel alignment. All calibrations are based off the centerline of the car body, so it’s very important that the wheels and the body are both pointing in the same direction. To confirm this we look at the thrust angle and adjust it as close to zero as we can.
ADAS calibration for some cars only
We decided not to buy an aftermarket ADAS calibration system. On the one hand, it would be very convenient to have coverage for every vehicle. On the other hand, aftermarket ADAS systems aren’t the same as the factory tools, and we aren’t qualified to determine if that’s OK.
We’ve seen some scary settlements in tire repair cases. Following factory procedures using factory tools seems like the best way to ensure that we keep the ADAS systems operating as designed, and avoid potential blame should the car later be involved in a collision.
This means that we’re buying targets one at a time. Unfortunately they can take up to six months to arrive.
Toyota has printable targets, and we have the Toyota radar reflector, so we should be able to calibrate nearly all Toyota vehicles. For Subaru we have two Eyesight targets and should be able to do most Subaru EyeSight calibrations. For Honda we have the target for calibrating the passenger side mirror camera. We don’t plan on adding ADAS calibration for Mazda or Nissan at this time.
ADAS Calibration Berkeley
So, if you’re looking for an ADAS calibration in Berkeley, Oakland, Emeryville, Albany, El Cerrito, or anywhere in the East Bay, give us a call.
If you’d like to read more about Subaru Eyesight Calibration, here’s another article.