PRE-CRASH SAFETY SYSTEM SYSTEM DESCRIPTION


  1. PRE-CRASH SAFETY SYSTEM DESCRIPTION


    1. The pre-crash safety system detects vehicles and obstacles in front of the vehicle and performs the following: 1) optimally uses system controls to avoid crashs, and 2) uses system controls to reduce impact during a crash.

  2. PRE-CRASH DETECTION OUTLINE


    1. Front crash detection


      1. The driving support ECU assembly receives information about vehicles and obstacles in front of the vehicle from the millimeter wave radar sensor assembly and object recognition camera. Then, based on vehicle speed, road conditions and obstacle location, the driving support ECU assembly determines, in advance, the risk of a crash and if a crash is unavoidable.

      2. The driver monitor camera detects the direction that the driver's head is facing and whether the driver's eyes are open or closed. When a potential crash is detected and the camera determines that the driver's head is not facing forward or that the driver's eyes are closed, it activates the pre-crash safety controls in advance.

    2. Rear-end crash detection


      1. The driving support ECU receives information about vehicles to the rear of the vehicle from the rear millimeter wave radar sensor. Then, based on the distance from the vehicle, relative speed, direction, etc., the driving support ECU determines, in advance, the risk of a rear-end crash and if a rear-end crash is unavoidable.

    3. Sudden braking detection


      1. The skid control ECU assembly activates the pre-crash seat belts when it detects sudden braking. Sudden braking is determined based on brake oil pressure and other information from the master cylinder pressure sensor.

    4. Vehicle control impossible judgment


      1. The pre-crash seat belts are activated when it is determined that there is a high probability that the vehicle cannot be controlled. The judgment is based on vehicle stability information from the yaw rate sensor and steering angle sensor.

    5. Component

      Component Detection Content
      Front millimeter wave radar sensor Front object
      Rear millimeter wave radar sensor Rear object
      Object recognition camera sensor Front object
      Driver monitor camera

      • Driver facial direction

      • Driver eye opening level signal

  3. PRE-CRASH SAFETY SYSTEM CONTROL DESCRIPTION

    Operation Condition Controls Sender ECU Receiver ECU Part Operated
    Front crash detected

    1. Crash is possible

    		 Pre-crash alarm Driving support ECU Skid control ECU Skid control buzzer

    1. Crash is unavoidable

    		 Pre-crash seat belts Driving support ECU Seat belt control ECU Front seat outer belts

    1. Crash is possible

    2. Crash is unavoidable

    • Pre-crash brake assist

    • Pre-crash brake

    		 Driving support ECU Skid control ECU Brake assist system

    1. Crash is possible

    2. Crash is unavoidable

    		 Air suspension control Driving support ECU Suspension control ECU Shock absorber

    1. Crash is possible

    		 Variable gear ratio steering control Driving support ECU Steering control ECU Steering actuator
    Rear-end crash detection

    1. Crash is possible

    		 Rear-end crash prevention alarm control Driving support ECU Main body ECU Hazard warning light*

    1. Crash is unavoidable

    		 Active headrest function Driving support ECU Active headrest control ECU LH Front headrest LH

    1. Crash is unavoidable

    		 Active headrest function Driving support ECU Active headrest control ECU RH Front headrest RH
    Sudden braking detected Pre-crash seat belts Skid control ECU Seat belt control ECU Front seat outer belts
    Vehicle control impossible judgment Pre-crash seat belts Skid control ECU Seat belt control ECU Front seat outer belts

    Tech Tips

    *: Except Europe

  4. PRE-CRASH ALARM CONTROL


    1. When the system determines that there is a risk of colliding with an obstacle in front of the vehicle, the multi-information display and warning buzzer are used to warn the driver and help with crash avoidance.

  5. PRE-CRASH SEAT BELT CONTROL


    1. When the system determines that a crash with an obstacle is unavoidable, that sudden braking has occurred, or that vehicle control is impossible, the system performs seat belt control. During seat belt control, slack in the seat belts is reduced to increase occupant restraint and aid the pretensioner.

  6. PRE-CRASH BRAKE ASSIST CONTROL


    1. When the system determines that there is a risk of colliding with an obstacle in front of the vehicle, brake assist is set to standby mode. Then, when the driver depresses the brake pedal, the hydraulic brake pressure is increased to improve braking effectiveness.

  7. AIR SUSPENSION CONTROL


    1. When it is determined that there is a risk of colliding with an obstacle in front of the vehicle, the AVS is operated to control the damping force, suppress nose diving and rolling, and support crash avoidance through steering.

  8. VARIABLE GEAR RATIO STEERING CONTROL


    1. When the system determines that there is a risk of colliding with an obstacle in front of the vehicle, the Variable Gear Ratio Steering (VGRS) system is set to standby at an optimum steering ratio (i.e., increasing power steering) for crash avoidance.

  9. PRE-CRASH BRAKE CONTROL


    1. When it is determined that the obstacle in front cannot be avoided, crash avoidance support is performed by operating the brakes to reduce the speed at the time of the crash and lessen the impact. If the vehicle stops due to the operation of the pre-crash brakes, the brakes are maintained for up to 2 seconds and then automatically released. After the vehicle stops, the pre-crash brakes can be released by depressing the accelerator or brake pedal.

  10. REAR-END CRASH PREVENTION ALARM CONTROL (Except Europe)


    1. When the system determines that there is a risk of a rear-end crash, the hazard warning lights blinks 180 times per minute to warn drivers to the rear of the vehicle.

  11. PRE-CRASH INTELLIGENT HEADREST


    1. When the system determines that a rear-end crash is unavoidable, the front headrests move forward to reduce the distance from the driver's and passenger's heads in order to help reduce head injuries.

    2. Each front headrest has a built-in electrostatic capacitor sensor that detects the distance from the headrest to the occupant's head, so that the headrest does not touch the head when the headrest moves forward.

      A001FH2E02
      *1 Before Operation
      *2 After Operation
      *3 25 mm (0.98 in.)
      *4 60 mm (2.36 in.)

  12. PRE-CRASH BRAKE CANCEL SWITCH


    1. When the pre-crash brake cancel switch in the No. 1 instrument panel under cover sub-assembly is turned ON, the pre-crash alarm, pre-crash alarm brake and pre-crash brake do not operate.

      Tech Tips

      While the pre-crash brake cancel switch is ON, the combination meter's PCS indicator light tuns ons.

  13. VSC OFF SWITCH


    1. When the VSC off switch is turned on, the pre-crash brake assist and pre-crash brake do not operate.

      Tech Tips

      After the VSC off switch is pressed, the PCS indicator illuminates and "Pre-crash brakes are disabled because VSC is OFF" is displayed in the multi-information display in the combination meter for 6 seconds.

  14. PRE-CRASH SAFETY SYSTEM OPERATING CONDITION

    Vehicle Condition Pre-crash Alarm Pre-crash Seat Belt*1 Pre-crash Seat Belt*2 Pre-crash Brake Assist Air Suspension Control Variable Gear Ratio Steering Control Pre-crash Brake Rear-end Crash Prevention Alarm Control*4 Pre-Crash Intelligent Headrest
    Engine switch off or on (ACC) X X X X X X X X X
    When warning message is displayed on multi-information display *1 *1 *1 *1 *1 *1 *1 *1 *1
    When seat belt(s) are fastened ○ *2 *2 ○ ○ ○ ○ ○ ○
    When own vehicle speed is 30 km/h (19 mph) or more, regardless of relative speed X ○ X X X X X X X
    When own vehicle speed is 15 km/h (10 mph) or more and relative speed is 15 km/h (10 mph) X X X X X X ○ X X
    When own vehicle speed is 5 km/h (3 mph) or more and relative speed is 5 km/h (3 mph) *5 X X X X X *5 X X
    When own vehicle speed is 5 km/h (3 mph) or more and relative speed is 30 km/h (19 mph) X X ○ X ○ ○ X X X
    Regardless of own vehicle speed, when relative speed of other vehicle is 10 to 90 km/h (6 to 56 mph), and rear-end full lap or rear-end 50% offset crash occurs X X X X X X ○ ○ ○
    When vehicle collides with object outside detection range of front millimeter wave radar sensor (side crash, rear-end crash, etc.) X *3 X X X X X X X
    When front millimeter wave radar sensor cannot detect possible crash object X *3 X X X X X X X
    When own vehicle speed is 30 km/h (19 mph) or above, and relative speed of other vehicle is 30 km/h (19 mph) or above X X X ○ X X X X X

    Tech Tips


    • ○: Operation

    • X: Not operation

    • *1: Inoperative parts are different depending on malfunction areas

    • *2: Only operates when seat belt is fastened

    • *3: Pre-crash seat belts may operate when brakes are suddenly applied

    • *4: Except Europe

    • *5: This function operates only for vehicles equipped with an object recognition camera.

  15. PRECAUTION FOR FRONT MILLIMETER WAVE RADAR SENSOR AND OBJECT RECOGNITION CAMERA SENSOR


    1. When the front millimeter wave radar sensor and object recognition camera sensor detect an object in front of the vehicle under the conditions described below, the driving support ECU may determine that a crash is unavoidable, and activates the pre-crash safety system. However, this is not abnormal.

      A001CHOE01

      Tech Tips


      • The pre-crash safety system does not activate when the pre-crash sensor detects safety cones and other plastic objects.

      • The pre-crash safety system may or may not activate when the pre-crash sensor detects the following objects: people, bicycles, motorcycles, trees, animals and snow fences.

      Object Type Example
      Object that cannot be detected Plastic items (safety cones)
      Object that cannot always be detected Bicycles, motorcycles, trees, animals, snow fences, etc.

  16. PRECAUTION FOR REAR MILLIMETER WAVE RADAR SENSOR


    1. When the rear millimeter wave radar sensor detects a vehicle condition described below, the driving support ECU determines that a crash is unavoidable, and activates the pre-crash safety system. However, this is not a malfunction.

      A001ENIE02
      *1 When stopped to turn right, vehicle passes from behind
      *2 When vehicle is driven straight ahead, vehicle passes from behind
      *3 When stopped on side of road, vehicle passes from behind
      *4 When vehicle is driven or stopped, vehicles approaches from behind suddenly

      Tech Tips

      Bicycles, bikes, etc. cannot always be detected by the rear millimeter wave radar sensor.