Lane Keep Assist: A Helpful Intervention

New GM models equipped with Lane Keep Assist (RPO UHX) help nudge drivers back in the right direction. The new safety feature helps drivers avoid crashes when unintentionally drifting from their lane by providing a gentle, momentary steering wheel correction, along with various alerts (if necessary), to help guide the vehicle back on course.

Available on many new Cadillac, Buick, GMC and Chevrolet models, Lane Keep Assist employs a number of advanced components to help keep drivers on their intended path. The components include:
  • Front View Camera Module
  • Lane Keep Assist Switch/Control Indicator
  • Instrument Cluster/Vehicle Direction Display
  • Radio (for warning beeps/chimes)
  • Safety Alert Seat (if equipped)
  • Yaw Rate Sensor
  • Electric Power Steering.

How it Works
For Lane Keep Assist to provide assistance, the following must occur: 
  • Vehicle speed must be between 59 km/h and 178k km/h
  • Lane markings are clearly visible
  • The system is turned on and is clean from any foreign debris. The vehicle should be kept clean for proper operation.

Stage 1 – Lane Keep Assist Intervention 
Lane Keep Assist employs two driver interventions. When the vehicle has unintentionally approached a detected lane marking without a turn signal being activated in that direction, and the driver has not actively responded by either steering, accelerating, or braking, the electric power steering system will provide a gentle, momentary correction (torque input to the steering) to help guide the vehicle back on course. Lane Keep Assist does not continuously steer the vehicle. This steering pushback is the first stage of warning/intervention. 

When torque is applied to the steering, the Lane Keep Assist indicator will turn amber. There are no chimes or haptic seat warnings at this point of Lane Keep Assist operation. 

Steering intervention is based on the forward looking sensor outputs, such as lateral offset of the vehicle, relative yaw angle and time-to-line crossing. In addition, other vehicle dynamics signals are needed; e.g., velocity, steering angle and yaw rate, for the purpose of a driver suppression of the steering intervention. The electric power steering system uses a torque sensor to detect driver inputs and relays that information to the front camera module. 

Stage 2 – Lane Departure Warning 

If active driver steering is not detected, the second stage warning/ intervention is a Lane Departure Warning (RPO UFL). This warning may activate as the vehicle crosses a lane marking, alerting the driver through several beeps or a Safety Alert Seat vibration, if equipped. The vibration will take place on the side of the seat where the lane departure occurs. In addition, the amber Lane Keep Assist indicator will flash. 

The Safety Alert Seat must be turned on in the vehicle settings in order for haptic seat feedback to occur.

Typically, the driver will apply more torque to the steering wheel when the Lane Keep Assist intervention occurs. As a result, Lane Departure Warning alerts are rare because they only occur if the driver does not apply significant torque to the steering wheel and the Lane Keep Assist steering intervention was not enough to prevent a lane departure. This circumstance tends to happen only at the entrance to some curves.

Testing the System 
Lane Keep Assist intervention may not occur when expected by some drivers while approaching a lane marking. Lane Keep Assist replaced Lane Departure Warning for the 2016 model year (although Lane Departure Warning remains a key component) and operation is slightly different.
For example, if the driver tries to “test” the Lane Departure Warning alert and overcomes the steering correction so that the vehicle intentionally crosses the lane marker, the Lane Departure Warning system may interpret this as active steering and, in many cases, may not provide an alert. Consequently, alerts will occur less frequently.

External Influences 
Proper functionality of the Lane Keep Assist system may be affected by some outside factors, such as: 
  • Nearby vehicles ahead (tailgating) 
  • Sudden lighting changes, such as going through a tunnel
  • Banked roads 
  • Poor lane markings. 

If these conditions exist, the driver is advised to turn off the system. In addition, it’s not recommended to use Lane Keep Assist while towing a trailer or driving in slippery conditions.