Cruise Assist Description And Function (Including Speed Adaptation And Traffic Sign Recognition)

Cruise Assist, Speed Adaptation und Traffic Sign Recognition System Components:

Radar, yaw rate, lateral acceleration, wheel speed and steering angle sensor
Windshield camera with traffic sign recognition
Control unit to detect own vehicle movement
Object recognition and classification
Distance control
Control units for motor, transmission and ESP with actuators
Multifunction steering wheel control unit
Head-up display

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Technical Description:

The radar sensor is mounted in the center of the lower front grill.

The system is a mid-range radar, and is linked with the ADAS module via a private CAN bus. It is necessary for driver assistance functions such as collision avoidance and speed adaptation.

A private CAN bus is used for communication between the ADAS ECU and front radar because of transfer speed and safety. Diagnostic trouble codes can be read out via the ADAS ECU.

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The windshield camera (SCAM) also uses a private FD CAN to communicate with the ADAS module.

They are powered by clamp 15, which is controlled by the body control module BCM.

Bus architecture VFe35 Plus

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(APL10) Adaptive Cruise Control (ACC)

Adaptive Cruise Control (ACC) is a driver assistance system that assists drivers, to guarantee safe and comfortable stop & go driving with full deceleration capabilities by automatically controlling the brake and throttle. As a driver assistance system, this feature adjusts the speed to maintain a safe distance from a vehicle ahead, or maintains the set speed, whichever speed is lower. The feature is also able to reduce the vehicle's speed in front of and in bends, to enable the bend to be taken at a safe and comfortable speed. When the vehicle has stopped due to the vehicle ahead also having stopped, the driver needs to manually confirm continuation after a stop of 3 seconds or more.

If the vehicle ahead is not moving, the ACC system will remain in holding state for up to 10 minutes.
If the time is between 3 seconds and 10 minutes, and there is a vehicle ahead, the driver can re-start by using resume button or tapping on the gas pedal.
If the holding time is between 3 seconds and 10 minutes, and there is NO vehicle ahead, the driver has to press the gas pedal until vehicle reaches 30 kph in order to reactivate ACC.
If holding time is more than 10 minutes, the electronic parking brake will be applied, and if there a vehicle ahead, the driver has to release the electronic parking brake and/or press the gas pedal to release the parking brake. The driver can then reactivate ACC.
If, after a holding time of 10 minutes, the ACC system is deactivated, and there is NO vehicle ahead, the driver needs to release the parking brake and/or press the gas pedal until the vehicle's speed is 30kph in order to reset ACC.

The driver must supervise the system under all conditions, and must be available to take the control of the longitudinal control. The driver is solely in control of the steering wheel.

This feature can be used in combination with Intelligent Speed Adaptation.

System architecture for ACC

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HMI state flow for ACC

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Speed Adaptation System Components:

Mid-range radar
Steering wheel control locations
HMI
ADAS

Technical Description:

Intelligent Speed Adaption (ISA):

Intelligent Speed Adaptation (ISA) is a driver assistance system that helps the driver not to exceed legally enforced speed limits, and so guarantee safe driving. When activated in combination with one of the longitudinal control assistance functions, this function automatically limits the set speed used by any of the longitudinal control assistance functions to the legal limit that has been detected. The driver must supervise the system under all conditions, and must be available to take the control of the vehicle. As an assistance system, the function will only assist the driver by adjusting the speed to the legal limit. The driver remains responsible for adhering to the legal speed limit whenever the function is not able to detect the correct speed limit.

This function can be used in combination with Highway Pilot (SAE Level 2) (APL03) and Adaptive Cruise Control (APL10). It is not a stand-alone function.

Vehicles driving ahead are detected with the help of the radar sensor The speed and distance are calculated up to about 200 m. A distinction is made between two operating states: "road clear" and "traffic ahead". The system is able to brake the vehicle if an obstacle is detected.

An MRGEN mid-range radar is used to detect objects ahead of the vehicle. The system works with a single wave beam. According to the manufacturer, the system can measure greater distances and accurately determine the distance, speed, angle and height of objects up to 200 meters away.

Diagnosis and Calibration:

If, in the course of repair work on the vehicle, changes are made that might affect the effectiveness of the radar sensor, then it must be adjusted.

Due to the structure of the ADAS system, the diagnostic tool cannot access the radar sensor directly. The radar communicates with the "ADAS ECU" via a "private CAN". The "ADAS ECU" can then be read out by a diagnostic tool.

The Mid-range radar is calibrated by positioning a flat metal plate in front of the vehicle and running the calibration process in Scan Tool.

System architecture of ISA

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HMI state flow of ISA

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Operation: (Use Cases)

Control locations - steering wheel (right-hand side)

The switches on the right-hand side control drive-related functions:

Adaptive cruise control
Intelligent speed limiter

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Check ACC preconditions in real time. ACC icon is shown in gray if available (meets the pre conditions)

Preconditions: Speed >= 20 km/h

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Traffic Sign Recognition Components:

Front windshield camera
HMI
ADAS

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Technical Description

Traffic Sign Recognition

The front camera recognizes differently shaped signs and the symbols. The information is sent to the central driver assistance control unit by the evaluation of the images. Since the traffic signs of different countries look different, these must be entered for the region concerned.

Traffic Sign Recognition (TSR) is a driver assistance system that shows drivers the current speed limit and any other traffic signs on the road from which is possible to infer the speed limit. Traffic sign recognition uses a camera mounted on the front windshield to capture traffic signs on the road ahead. The system uses recognition software to detect a traffic sign and then display this information on the infotainment and/or head-up displays. Speed limits are also inferred from ISA maps. When Adaptive Cruise Control is active and the Intelligent Speed Assist button is pressed, the vehicle's speed will be automatically adjusted in accordance with the speed limit detected and the user-configured speed offset value that has been set. It will issue a warning when the driver exceeds these speed limits.

In addition, the system can also detect other non-speed-related traffic signs including bicycle paths, expressways, tunnels, slippery roads, pedestrian crossings. In the US, it will recognize speed limit, ramp speed, curve speed, school speed, end of speed limit, etc.

Activation: The system is activated when the vehicle's speed is over x kph.

Deactivation: The system is deactivated when vehicle's speed is less than x kph, or the user switches it OFF at the HMI.

According to the speed limit and vehicle's speed, the function will trigger the appropriate warning level. There will be 3 warning levels. These cold be:

No warning: vehicle speed < speed limit (TBD)
Level 1 warning: (vehicle speed - speed limit)/speed limit < 5% --> the speed sign flashes on the IPC with frequency of 1Hz (tbd)
Level 2 warning: 5 % <= (vehicle speed - speed limit)/speed limit < 10% --> the speed sign flashes on the IPC with a frequency of 2Hz (tbd)
Level 3 warning: 10 % <= (vehicle speed - speed limit)/speed limit --> the speed sign flashes on the IPC with frequency of 4Hz (tbd)

If there is no speed limit or end of speed limit, the warning function does not work.

The function sends the recognition sign and warning signals to the infotainment system, which informs to driver.

The driver can enable/disenable the function on the MHU

If the function detects any failure of itself or ADAS systems, it will trigger a MALFUNCTION warning and send it to the infotainment system, to alert the driver. The ADAS system can detect hardware/software failures that stop the function from working properly; the not-available function alert is sent to the HMI/IPC, etc.

The function sends the recognition sign and warning signals to the infotainment system, which informs to driver.

The driver can enable/disenable the function on the MHU

TSM system performance may be impacted in the following conditions:

Poor visibility due to snow, fog or heavy rain
Due to glare from oncoming traffic or the sun
At high speed
If the camera's visual field is covered with dirt or stickers
If the traffic signs are completely or partially covered
If traffic signs do not conform to the standard format
If traffic signs are damaged or bent
If traffic signs are displayed on sign holders with electronic signs
If the traffic signs or the roadways have changed and the
Navigation data is no longer up-to-date

System architecture of TSR

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HMI state flow of TSR

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Operation: (Use Cases)

To Activate Traffic Sign Recognition:

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Open "Driver Aids" app from the app drawer or quick control card
Open "Driving Assistance"
Touch to turn "On/Off"