PRE-CRASH SAFETY SYSTEM SYSTEM DESCRIPTION


  1. PRE-CRASH SAFETY SYSTEM DESCRIPTION

    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 crashes, and 2) uses system controls to reduce impact during a crash.

  2. PRE-CRASH DETECTION OUTLINE


    1. Front crash detection

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

    2. Sudden braking detection

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

    3. Vehicle control impossible judgment

      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.

  3. PRE-CRASH SAFETY SYSTEM CONTROL DESCRIPTION

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

    1. Crash is possible

    2. Crash is unavoidable

    		 Pre-crash alarm Driving support ECU Combination meter assembly Combination meter assembly
    Skid control ECU Skid control buzzer
    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 Driving support ECU Skid control ECU Brake assist system
    Crash is unavoidable Pre-crash brake

    1. Crash is possible

    2. Crash is unavoidable

    		 Air suspension control* Driving support ECU Suspension Control ECU Shock absorber
    Sudden braking detected Pre-crash seat belts Skid control ECU Seat belt control ECU Front seat outer belts
    Vehicle control impossible judgment

    • *: w/ AVS

  4. PRE-CRASH ALARM CONTROL

    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

    If the pre-crash sensor detects that a collision is unavoidable, the pre-crash safety system retracts the seat belt, thus enhancing the effectiveness of the seat belt pretensioner in a crash. The same happens if the driver makes an emergency braking or loses control of the vehicle.

  6. PRE-CRASH BRAKE ASSIST CONTROL

    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. PRE-CRASH BRAKE CONTROL

    When the system determines that a crash with an obstacle is unavoidable, the system performs brake control to reduce the vehicle speed.

  8. AIR SUSPENSION CONTROL

    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 collision avoidance through steering.

  9. PRE-CRASH BRAKE CANCEL SWITCH ASSEMBLY

    When the pre-crash brake cancel switch assembly in the No. 1 instrument panel under cover sub-assembly*1 or No. 2 instrument panel under cover sub-assembly*2 is turned on, the pre-crash alarm and pre-crash brake do not operate.


    • *1: for LHD

    • *2: for RHD

    Tech Tips

    While the pre-crash brake cancel switch assembly is on, the PCS indicator light in the combination meter assembly illuminates.

  10. PRE-CRASH SAFETY SYSTEM OPERATING CONDITION

    Vehicle Condition Pre-crash Alarm

    Pre-crash Seat Belt

    (Linked with Understeer or Oversteer Tendency Operation and Sudden Brake Operation)

    Pre-crash Seat Belt

    (Linked with Radar)

    		 Pre-crash Brake Assist Pre-crash Brake Control Air Suspension Control*3
    Ignition switch is off or ACC X X X X X X
    Pre-crash brake cancel switch assembly is on X ○ ○ ○ X ○
    Warning message is displayed on multi-information display *1 *1 *1 *1 *1 *1
    Seat belt(s) are fastened ○ ○ ○ ○ ○ ○
    Vehicle speed is 30 km/h (18 mph) or more, regardless of relative speed X ○ X X X X
    Vehicle speed is 15 km/h (9 mph) or more and relative speed is 15 km/h (9 mph) ○ X X X ○ ○
    Vehicle speed is 5 km/h (3 mph) or more and relative speed is 30 km/h (18 mph) X X ○ ○ X ○
    Vehicle speed is 30 km/h (18 mph) or more and relative speed is 30 km/h (18 mph) X X X ○ X ○
    Vehicle collides with object outside detection range of millimeter wave radar sensor assembly X *2 X X X X
    Millimeter wave radar sensor assembly cannot detect possible collision object X *2 X X X X

    • ○: Operation

    • X: No operation

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

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

    • *3: w/ AVS

  11. PRECAUTION FOR MILLIMETER WAVE RADAR SENSOR ASSEMBLY


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

      A009BGDE01

      Tech Tips


      • The pre-crash safety system is not activated by safety cones and other plastic objects which cannot be detected by the millimeter wave radar sensor assembly.

      • The pre-crash safety system may or may not be activated by the following objects which cannot always be detected by the millimeter wave radar sensor assembly: people, bicycles, motorcycles, trees, animals, snow fences, etc.

      Object Type Example
      Object that cannot be detected Safety cones, plastic items
      Object that cannot always be detected People, bicycles, motorcycles, trees, animals, snow fences, etc.