Emergency Lane Keeping (ELK)
Emergency Lane Keeping (ELK) is a driver assistance system that avoids or lessens the severity of accidents by automatically applying a heading correction when a vehicle is about to drift beyond a solid lane marking, the edge of the road or into oncoming or overtaking traffic in the adjacent lane.
While LKA (an assistance function) assists the driver to stay in its lane by applying small steering corrections, ELK is a safety function and if needed will use a more aggressive steering control to keep the vehicle in its lane. The system detects the lane markings, road edges and oncoming or overtaking vehicle in the adjacent lane and avoids drifting to the road edge or collision by steering interaction.
Unlike the "Lane Departure Warning" and the "Lane Keeping Assist", the "Emergency Lane Keeping" does not rely exclusively on information from the S-Cam, but also uses the Mid Range Radar and the 4 Short Range Corner Radar sensors for object detection.
When "Emergency Lane Keeping" is activated, the system working speed range is from 60-150 kph.
Once the system has been activated, it is operational if the following conditions are met:
- No LKA fault is detected;
- No camera failsafe;
- Cluster vehicle speed is in between 60 kph-150 kph;
- Lateral acceleration absolute value is smaller than <3 m/s2 ;
- both lane boundaries are detected and
- lane width is wider than the minimum limitation >2.5m or
- only one lane boundary is detected;
- Vehicle is in the "Non-intervention zone" - between left EKL and right EKL;
- Lane curvature absolute value is smaller than <0.0035;
- ABS, TCS and VSE are all inactive;
- Vehicle is in any forward gear;
- Longitudinal acceleration value is smaller than <3m/s2 ;
- Longitudinal deceleration absolute value is smaller than <3m/s2 ;
- Hazard switch is off; or
- No hands-off reset.
The system is disabled when one of the following conditions are met:
- Pressing the accelerator pedal faster than the threshold rate;
- Pressing the brake pedal more than a threshold value;
- Exceeding the threshold value of steering torque;
- Active safety system interventions (ABS or TCS or VSE is active);
- Steering wheel angle is out of range (the limitation is a map based on vehicle speed);
- Steering wheel speed is bigger than 200°/s;
- Vehicle is within left/right intervention zone when left turn indicator is ON without left oncoming or overtaking vehicle;
- Camera is in failsafe mode;
- Cluster vehicle speed is less than 55 kph or greater than 155 kph;
- Lateral acceleration absolute value exceeds 3.5m/s2;
- Both lane boundaries are detected and lane width is narrower than 2.45 m;
- No lane boundary is detected;
- Vehicle exceeds the latest keeping line (LKL);
- Lane curvature absolute value is greater than >0.004;
- Vehicle is not running forward;
- Gear shift position is in R;
- Longitudinal acceleration is greater than >3.5m/s2 ;
- Longitudinal deceleration absolute value is greater >3.5m/s2 ;
- Hazard switch is on;
- Hands-off reset;
- LSS to EPS handshake is failed;
When the "Lane Keeping Assist" (LKA) is activated, ADAS receives information on the following:
- Status of the "Integrated Dynamic Brake"*
- The vehicle speed;
- An activated turn signal;
- The yaw rate;
- The door status (open/closed);
- The tire pressure monitoring system;
- The status of the trailer module;
- The status of the hands-on sensor;
- The steering wheel angle; or
- The gear engaged.
*) additional information on "Lane Keeping Assist (LKA)"
The camera provides information on the lane markings and the position of the vehicle within the lane. The Mid Range Radar (MRR) and the 4 side radars/Short Range Radar (SRR) provide information on the traffic situation - oncoming traffic and vehicle traffic in adjacent lanes.
If the ADAS detects the vehicle approaching one of the lane marking, the color of the lane limit changes to red, and at the same time a command is issued to the Electrical Power Steering for a haptic warning. The system issues a warning message via the Multimedia Head Unit (MHU).
In the event that the vehicle drifts out of the lane or collision, the system initiates corrective steering movements and guides the vehicle back into the lane. The system thus prevents the vehicle from
- drifting out of the lane;
- drifting out of the lane and entering oncoming traffic, possibly causing a collision; and
- colliding with a vehicle in the adjacent lane.
IDB - Integrated Dynamic Brake
BCM - Body Control Module
HOD sensor - Hands-on-wheel-sensor
EPS - Electrical Power Steering
PWT - Powertrain
MHU - Multimedia Head Unit (MHU)/Multimedia Display Unit (MDU)/HMI
EPS - Electrical Power Steering
TPMS - Tire Pressure Monitoring System
MRR - Mid Range Radar
SRR - Short Range Corner Radar (front and back)
HMI state flow