Buick Regal: Lane Keep Assist Description and Operation

NOTE:

• The Lane Keep Assist system DOES NOT continuously steer the vehicle
• The Lane Keep Assist system replaces Lane Departure Warning System
• Lane Departure Warning will have more alerts than Lane Keep Assist (visual, audible, and haptic warning

The system assists driver to keep vehicle in-lane by providing a steering push back to the vehicle when an unintended lane departure is detected. See the user's manual for more detailed information on vehicle personalization.

The lane keep assist system is made up of the following components:

• Front view camera module
• Lane Keep Assist switch/control indicator
• Instrument cluster/Vehicle Direction Display
• Radio
• Safety Alert Seat (if equipped)
• Yaw rate sensor
• Electric power steering

Front View Camera Module

The camera detects visual queues such as lane markings. When it is determined that the vehicle has unintentionally moved outside of the lane, visual, and audible or haptic warning is given to the driver.

The front view camera module receives an input from the lane keep assist switch and controls the lane keep assist switch indicator output. The front view camera module also communicates via serial data with the instrument cluster, radio, and memory seat module to request visual, and audible or haptic alerts.

Lane Keep Assist Switch

The lane keep assist switch provides an input to the front view camera module to turn the lane keep assist system ON and OFF. The front view camera module provides a signal voltage to the normally open momentary switch. When the switch is pressed, the signal circuit is pulled to ground, indicating to the front view camera module that the system has been requested to turn ON or OFF. The lane keep assist switch also contains the lane keep assist switch indicator, which is controlled by the front view camera module to indicate the ON and OFF status of the lane keep assist system. When the system has been enabled by the lane keep assist switch, the front view camera module applies ground to the switch indicator and illuminates the LED. The location of the lane keep assist switch can vary with different vehicles. For the exact location please refer to the user's manual.

Instrument Cluster

The vehicle direction display contains green and amber lane keep assist indicators. These indicate to the driver the current status of the lane keep assist system and are controlled via serial data by the front view camera module. When the vehicle speed is above 56 km/h (35 MPH) and the system has detected the required lane markings and is ready to assist, the green indicator will be illuminated on the vehicle direction display. If the vehicle has unintentionally left the lane, the amber indicator will flash.

Radio

The radio controls the audible alert for the lane keep assist. If the vehicle has unintentionally left the lane, the radio will command three beeps as an audible alert to the driver.

Safety Alert Seat (if equipped)

The memory seat module controls the haptic alert provided by the seats. If the vehicle has unintentionally left the lane, and the Electric Power Steering determines the corrective action requires an above threshold amount of effort, the memory seat module will command three pulses to the left or right side of the seat, depending on the lane departure direction.

Yaw Rate Sensor

The 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. Over that, other vehicle dynamics signals are needed, e.g. velocity, steering angle, yaw rate for the purpose of a driver suppression.

Electric Power Steering

The electric power steering uses a torque sensor to detect driver inputs and relays that information to the frontview camera module. The electric power steering is used to provide steering push back.

Lane Keep Assist Operation

There is two stages of warning/intervention for the driver: The first stage is the steering push back, if the lane keep assist system detects that the vehicle will cross the lane marking despite it is intervening, a second stage warning shall be issued. The second stage warning is a chime or a haptic seat vibration, if equipped with haptic seats. If a haptic seat vibration is used as stage 2 warning, the vibration shall take place on the side of the seat, where the lane departure happened.

System operation can be described by the following modes:

• Off State: The system has been turned off by the driver using the lane keep assist switch. The lane keep assist indicator will not be illuminated.
• Not Ready To Assist: The system is enabled and the lane keep assist indicator is illuminated, but not ready to assist when any of the following conditions is true:
  • Vehicle speed is less than 37 MPH (60 km/h). The system is designed to function at speeds greater than 37 MPH (60 km/h).
  • The system cannot detect lane markings. This may be because there are no lane markings, as on a country road or that the lane markings cannot be determined due to snow, rain, or other driving conditions.
  • The windshield area in front of the camera or the camera lens is blocked by fog, dirt, damage to the windshield or other elements that may prevent the camera from detecting lane markings.
• Ready To Assist: The system is enabled and ready to warn of the unintentional lane crossing. The system is ready to assist when the green lane keep assist indicator is illuminated on the vehicle direction display.

Lane Crossing Alerts

• When one of the following conditions are met, the system will not give alerts:
  • The correct turn signal is activated. An activated turn signal is interpreted as an intentional lane crossing.
  • The operator makes an intentional steering maneuver.
  • The operator makes an intentional accelerating maneuver.
  • The operator makes an intentional braking maneuver.
• Lane crossing alert consists of the following:
  • The amber lane keep assist indicator will flash.
  • "push-back" steering torque input (or nudge) from Electric Power Steering to help prevent a lane departure
  • Three chimes are activated through the radio.
  • or if equipped , three pulses to the left or right side of the seat.

Lane Keep Assist System Driver Information Center Messages

The front view camera module can command the driver information center to display the various messages to alert the driver of a system concern or status information. For detailed information about the possible messages please refer to the user's manual.

SAFETY ALERT SEAT DESCRIPTION AND OPERATION

The safety alert seat provides a vibration in the driver's seat bottom cushion to alert the driver of a number of concerns. Two seat haptic movement motors are utilized to create the vibration and are located on the left and right sides of the seat cushion. Utilizing two motors allows the vibration to be localized to the left or right side of the seat, depending on the side of the vehicle generating the alert, or to vibrate both simultaneously.

The active safety seat utilizes the following components:

• Seat Memory Control Module
• Seat Haptic Movement Motor - Driver Left
• Seat Haptic Movement Motor - Driver Left

Seat Memory Control Module

The seat memory control module receives serial data messages from other modules and provides voltage to control the seat haptic movement motors. The seat memory control module will pulse the left, right, or both motors with the number of pulses requested over serial data. The seat memory control module monitors the control circuits for open, short to ground, and short to voltage conditions and will set DTCs if a circuit fault is detected.

Seat Haptic Movement Motor

The seat haptic movement motor is DC motor located in the driver's seat bottom cushion. Two seat haptic movement motors are used in the seat bottom cushion, positioned on the left and right side. An offset weight is attached to the motor. When activated, the spinning offset weight creates a vibration felt by the driver through the seat cushion.

Each seat haptic movement motor receives a constant chassis ground. The motor is controlled by the seat memory control module providing voltage through a dedicated control circuit. When an alert is required, the seat memory control module will apply voltage, activating the seat haptic movement motor.

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