ADAS – The Whole Story
Automotive technology is constantly changing. One of the most innovative developments over the past decade has been the rise in Advanced Driver Assistance Systems (ADAS). ADAS is designed to make vehicles safer, with features like automatic emergency braking, lane departure warnings, and blind-spot monitoring.
To work properly, ADAS relies on a series of equipment that monitors the area around the vehicle. The type of equipment varies based on the vehicle model, but the most common ones are ultrasonic sensors, cameras, and radar. Some systems use information from a single sensor, while others utilize information from several sensors, known as “sensor fusion.”
Why ADAS Calibration is Important
ADAS sensors have precise placement on vehicles and must be calibrated if they’re moved even slightly. For example, a sensor on a car that is even a millimeter off will be aimed at an area that’s significantly off axis 50 feet down the road. Sensors are often knocked out of alignment due to collisions, but depending on the type of car, they’re also often affected by things like wheel alignments, suspension repair, and windshield replacement.
Calibration is necessary to realign the sensors properly. Failing to do so can cause them to provide faulty information, which can make the ADAS system malfunction or not work at all. Here are a few problems caused by faulty sensor input:
· A warning light or message on the instrument panel
· A diagnostic trouble code (DTC) stored in your vehicle’s computer memory
· Steering wheel vibration
· Steering pull
· Increased steering effort.
These issues can be dangerous, especially if they affect the steering. The ADAS system may also be unable to provide safety alerts, such as blind-spot monitoring, which can increase the risk of accidents. Having a malfunctioning system may also cause you to lose faith in your car’s safety features. Here’s a closer look at each sensor type:
Front-Facing Camera Sensors
Many vehicles are equipped with this type of sensor. They’re commonly used for:
· Automatic emergency braking
· Adaptive cruise control
· Lane departure warnings
· Lane-keeping assist
· Automatic headlight high-beam activation and dimming
Cameras are optical devices, so they need to be able to “see” the road. Many camera sensors are mounted against the inside of the windshield as part of an assembly integrated with the rearview mirror. Other types may be directly attached to the roof or as part of a mirror housing. Some manufacturers will use dual cameras that are spaced apart to offer better depth perception.
The high definition image receptors in these sensors are similar to those found in other types of digital cameras. ADAS camera sensors are unique because they use high-powered microprocessors and advanced data processing algorithms that change the analog image into digital information that can be used by the ADAS system.
The camera sensors view the road through the windshield and require specific rates of light transmission through the glass. For this reason, the glass must have minimal distortions or imperfections; if any are present, it can impact the ability of the sensor to collect accurate information. This is why many auto manufacturers specify that their vehicles require Original Equipment Manufacturer (OEM) windshield replacement is necessary on models equipped with ADAS sensors. Some dealerships won’t calibrate sensors on cars with aftermarket windshields. Lucky Dog Auto Glass has these capabilities and is happy to discuss your options with you.
Around-View Camera Sensors
Some newer vehicles use simpler, low-resolution cameras equipped at the front, rear, and sides of the vehicle to provide a 360-degree overhead view around the vehicle. They’re typically located in the front bumper or grill, under the side mirrors, and in the trunk lid or liftgate. The car’s computer combines the multiple images from the cameras to create an overall view that can be displayed on the infotainment dash screen. While these camera sensors are not as complicated those in ADAS systems, they do require calibration.
Front-Facing Radar Sensors
Front-facing radar sensors are used for features like:
· Adaptive cruise control
· Forward collision warning
· Automatic emergency braking
These sensors transmit a high-frequency radio signal that reflects off objects and returns to the sensor. The sensor then uses the amount of time for the signal to return to calculate the car’s distance from another car or object. The radar sensors are usually mounted in or behind the front bumper or grille and often have some sort of cover to protect them from damage. Many radar sensors are mounted in the center of the vehicle, but they can also be offset to one side.
Radar sensors are often hidden, which can make it difficult to determine whether a vehicle has them by visual inspection alone. One way to check is to look for adaptive cruise control switches inside the car (they’re typically on the steering wheel) or to look for a warning light for an emergency braking or adaptive cruise control system that illuminates on the dash when the car starts.
Other Types of Radar Sensors
Some rear collision warning and blind-spot monitoring systems use small radar systems mounted under the side view mirror, behind the rear bumper cover, or in the taillights. Those mounted in the bumper or taillights may also provide rear cross-traffic alerts to aid backing out of parking spaces.
Most auto manufacturers don’t allow repairs on bumper covers in front of radar sensors because it can cause interference. They also recommend using only OEM bumper covers that are designed to work with the radar sensors. Automakers also advise against putting bumper stickers near the radar sensors as these can cause interference as well.
Ultrasonic sensors are generally used for parking assistance, blind-spot monitoring, and self-parking systems. They’re installed in the front and/or rear bumper covers. Ultrasonic sensors work similarly to radar sensors, but they use reflected high-frequency sound waves to detect objects around the vehicle. Unlike other sensors, ultrasonic sensors don’t need calibration, but they do need to be placed very precisely to work properly. For this reason, some automakers discourage the use of aftermarket, reconditioned, or recycled parts. These parts may not have the necessary predrilled holes that allow the sensors to work properly, or they could be warped or distorted.
Steering Angle Sensors
These sensors are typically built into the steering column and measure the degree of steering wheel rotation. They’re used for:
· Lane departure warnings
· Adaptive headlights
· Electronic stability control
· Adaptive suspensions
As previously mentioned, ADAS sensor calibration is needed any time a sensor’s aim is altered in any way. They can be disturbed by a fender bender or simply routine repairs or maintenance. Calibration is also needed if:
· A sensor or its mounting bracket is removed or replaced
· There’s a change in tire size
· A front airbag deploys and deflects off the windshield
· Repairs are made to a roof with a sensor bracket mounted on it
· When there is a related DTC in the car’s computer memory
· The automaker releases a technical service bulletin that specifies calibration be done as part of another repair
Sensor replacement and recalibration are common with collision repairs and windshield repairs. Automakers recommend shops perform a complete diagnostic before the repairs are done as well as once the repairs are complete. This helps shops know if the system was working properly before they begin the work and to confirm that all the issues have been resolved afterward.
ADAS calibration can be complex and time-consuming. Some sensors can be calibrated at the shop, while others may require the vehicle to be driven. Some sensors may require both methods. Calibration time can vary depending on which methods are needed. Simpler calibrations can take about 30 minutes while the more complicated ones can take an hour or more. When calibration is needed, it adds to labor and repair costs.
Items Needed for Sensor Calibration
Since sensor calibration is very precise, many repair shops and windshield installers send their clients to the dealership to have it performed. It’s a significant investment to perform sensor calibrations as it requires specialized tools:
· Service information that describes the equipment and procedures for the year, make, and model of vehicle. This is occasionally available aftermarket, but generally must be obtained from the manufacturer. Either option is an expense for the shop.
· A car computer scanner that supports ADAS sensor calibration. These are available for the factory for specific automakers or an aftermarket device. Special tools that are designed specifically for ADAS sensor alignment are also available.
· A large, level, well-lit facility without clutter or metallic objects. This gives the necessary room to make sure the sensor’s aim and positioning are correct and eliminates objects that could interfere with the sensor calibration.
· A wheel alignment rack. Many automakers either require or recommend a four-wheel alignment to be done before ADAS calibration. This ensures the vehicle’s centerline is straight while the steering wheel is centered. The ADAS sensors can then be calibrated in alignment with the center of the vehicle.
Preparing Your Vehicle for ADAS Calibrations
There are also manufacturer requirements shops must follow to prepare the vehicle for calibration. Some common ones include:
· No unnecessary or heavy items in the vehicle
· Proper tire pressure
· Front and rear vehicle ride height within specifications
· A full fuel tank
· A clean windshield (if applicable)
· Removing the protective cover from the radar sensor (if applicable)
· Performing a wheel alignment (if applicable)
There are two types of ADAS sensor calibration methods: static and dynamic. The process can vary significantly depending on the make and model of the vehicle, but here’s an overview of the general process for each method:
This is also referred to as “in-shop” calibration. This begins with establishing the centerline (also called thrust line) of the vehicle. There’s a variety of measuring methods and tools specified by automakers for this process but often the tools are attached to or aligned with the front and rear wheel hubs. The next step involves positioning special targets in locations that are relative to the thrust line and sensor. The targets must be at a specific height, and many must be used with specialized adjustable mounting stands.
Camera sensor aiming targets are generally black and white patterned images that are purchased or downloaded. Some vehicles require specific lighting for proper calibration. Radar targets are similar to those of camera sensors, but they include metal elements. These will reflect radio waves back to the sensor. There are also metal cone-shaped radar targets. These are positioned with the open end of the cone facing the vehicle, which allows the radio waves to reflect to the sensor.
Some vehicles may also require the sensors to be mechanically leveled. For example, Volvo uses a bracket with a bubble level that fits over the radar sensor housing. A screw mechanism is used to adjust the sensor’s horizontal aim, which requires the vehicle to be on a perfectly level surface.
After the previous calibrations have been made, the last step is to initiate the aiming process with a scan tool. After initialization, the process is automatic. If additional adjustments are necessary, the scan tool will provide instructions. Once static calibration has been completed, many ADAS systems require a dynamic calibration. Even if it’s not required, a test drive is recommended to ensure proper calibration of the system and to check for ADAS diagnostic codes. Some systems will not display codes or error messages until the car has been driven a set distance.
Dynamic (On-Road) Calibration
Dynamic calibration is often the only method required for camera sensors, while radar sensors often require both static and on-road calibration. During dynamic calibration, the process is initiated with a factory scan tool, then the car is taken for a drive on a straight road with clear lane markings. The car is driven for 5 to 30 minutes at the required speeds until the scan tool says the calibration is finished. Some cars may also display a warning light or a message on the dash to indicate the calibration completed successfully.
Depending on the vehicle, calibration may work better with minimal traffic; other vehicles calibrate faster when more traffic is detected. Calibration often isn’t recommended during weather conditions that make the lane markings difficult to see or when it’s not safe to drive at the required speeds.
Around-View Camera Calibration
This type of calibration is required when one or more of the cameras are replaced or when a mounting part is removed or replaced. Around-view cameras typically require only static calibration, although some systems require an on-road dynamic method. With static calibration, large patterned mats are placed around the vehicle, then the factory scan tool is used to initiate calibration.
Steering Angle Sensor Calibration
This type of calibration may be needed after an airbag deploys, structural repairs are performed, or the wheels are aligned. Steering angle sensor calibration generally involves facing the wheels straight ahead, then using a scan tool to zero out the sensor’s signal.
Higher Costs, Improved Vehicle Safety
ADAS systems make vehicles safer and easier to drive, but they also make them more complex when it comes to certain repairs. Having a windshield replacement or wheel alignment on a car with an ADAS system is often significantly more expensive than a car without one. This is because of the additional labor and processes to calibrate the sensors properly, as well as the necessity for OEM parts. However, it’s well worth having the peace of mind that your vehicle’s safety features are working as they should.