DYNAMIC RADAR CRUISE CONTROL SYSTEM SYSTEM DESCRIPTION


  1. GENERAL


    1. The dynamic radar cruise control system has 2 cruise control modes: constant speed control mode and vehicle-to-vehicle distance control mode.


      • Vehicle-to-vehicle distance control mode is selected by default when the dynamic radar cruise control system is turned on using the cruise control main switch (ON-OFF button).

      • Operation of constant speed control mode is the same as that for a conventional cruise control system.

    2. This system maintains the vehicle at the speed that the driver has set, as long as there are no vehicles ahead. In addition to this, the system maintains the vehicle-to-vehicle distance that has been set by the driver. If the system detects a vehicle driving at a slower speed ahead while the driver is driving at a constant speed, it controls the engine to decelerate the vehicle. If further deceleration is required, the system controls the brake actuator in order to apply the brakes. Thereafter, if there are no vehicles ahead within the set vehicle-to-vehicle distance because either the vehicle ahead or the driver has changed lanes, the system accelerates slowly to reach the set speed and resumes driving at this speed.

    3. Constant speed control mode is designed to maintain a constant vehicle speed. Vehicle-to-vehicle distance control mode is designed to control vehicle speed and vehicle-to-vehicle distance using the constant speed function, deceleration cruising function, follow-up cruising function, and acceleration cruising function.

    4. The millimeter wave radar sensor assembly and the driving support ECU assembly control the system while vehicle-to-vehicle distance control mode is operating, and send signals to each actuator and ECU.

    5. In vehicle-to-vehicle distance control mode, the dynamic radar cruise control system receives signals from the yaw rate sensor and the steering angle sensor. Based on these signals, the system then estimates curve radius and compensates for information on the preceding vehicle while turning. It can also compensate using brake control when approaching another vehicle.

    6. This system judges the presence of a vehicle in front and the distance to it based on the signals from the radar sensor while vehicle-to-vehicle distance control mode is operating. Using this information, the system informs the driver of danger with the warning buzzer, performs brake control, and turns on the stop lights when approaching a vehicle in front.

    7. The following illustration shows a control example under the following conditions: own vehicle speed is 100 km/h (62 mph) and the speed of the vehicle in front is 80 km/h (50 mph). The vehicle distance can be set to any of the following 3 distances by operating the cruise control main switch (vehicle-to-vehicle distance control switch): long (approximately 50 m (164 ft.)), middle (approximately 40 m (131 ft.)), and short (approximately 30 m (98 ft.)) when the vehicle speed is approximately 80 km/h (50 mph).

      A01I239E02

      Tech Tips


      • Vehicle distance increases and decreases in accordance with vehicle speed.

      • Control conditions are indicated on the combination meter assembly.

  2. FUNCTION OF MAIN COMPONENTS

    Item Outline
    Combination Meter Assembly (Cruise Control Indicator (Vehicle-to-Vehicle Distance Control Mode))

    • Comes on when the dynamic radar cruise control system is turned on using the cruise control main switch (ON-OFF button).

    • If the driving support ECU assembly detects a malfunction, this light goes off to warn the driver.
    Combination Meter Assembly (Cruise Control Indicator (Constant Speed Control Mode)) Comes on when the dynamic radar cruise control system is turned on using the cruise control main switch (ON-OFF button), and constant speed control mode is selected.
    Combination Meter Assembly (Cruise Control SET Indicator) The ECM illuminates the cruise control SET indicator in the combination meter assembly when constant speed control is started by pushing the cruise control main switch to -/SET.
    Combination Meter Assembly (Buzzer) If the ECM or driving support ECU assembly detects an automatic cancel signal while the dynamic radar cruise control system is controlling vehicle speed, this buzzer sounds only once to inform the driver.
    Combination Meter Assembly (Multi-information Display)

    • While the system is in vehicle-to-vehicle distance control mode, the multi-information display receives signals from the driving support ECU assembly, in order to display system conditions in the graphic area.

    • If the ECM or driving support ECU assembly detects a malfunction signal while the vehicle is operating under cruise control, a warning message will be displayed in the warning area to inform the driver.
    Cruise Control Main Switch (ON-OFF button) Turns the dynamic radar cruise control system on or off.
    Cruise Control Main Switch (Control Switch)

    • Vehicle speed setting, deceleration, preset speed resumption, acceleration, and cancel request signals are sent to the ECM through the operation of this switch.

    • Switches the control mode: constant speed control mode and vehicle-to-vehicle distance control mode.
    Steering Pad Switch Assembly (Vehicle-to-vehicle Distance Control Switch) While the system is in vehicle-to-vehicle distance control mode, the driver can operate the steering pad switch assembly (vehicle-to-vehicle distance control switch) to select the vehicle-to-vehicle distance in 3 stages: long, middle, and short.
    Stop Light Switch Assembly Detects the depression of the brake pedal and transmits signals to the ECM.
    Windshield Wiper Switch Assembly Transmits wiper control switch information to the driving support ECU assembly.
    Millimeter Wave Radar Sensor Assembly Radiates radar waves forward, uses the reflected waves for detecting the presence of a vehicle in front, vehicle-to-vehicle distance, and relative speed, and transmits this information to the driving support ECU assembly.
    Steering Angle Sensor Detects the angle and direction of steering and transmits signals to the driving support ECU assembly.
    Vehicle Speed Sensor (SP1) A vehicle speed signal which is output from the skid control ECU (brake actuator assembly) is sent to the ECM and driving support ECU assembly.
    Airbag Sensor Assembly (Yaw Rate Sensor) Detects the yaw rate of the vehicle and transmits signals to the driving support ECU assembly.
    Brake Actuator Assembly Actuates the brakes in accordance with signals from the skid control ECU (brake actuator assembly).
    Skid Control ECU (Brake Actuator Assembly) While the system is in vehicle-to-vehicle distance control mode, the skid control ECU (brake actuator assembly) actuates the brake actuator in accordance with a brake request signal received from the driving support ECU assembly.
    Skid Control Buzzer Assembly This buzzer sounds upon receiving signals from the driving support ECU assembly.
    ECM

    • Controls the dynamic radar cruise control system in accordance with signals from switches, sensors, and the driving support ECU assembly.

    • If the ECM detects a malfunction in the dynamic radar cruise control system, it will store DTCs (Diagnostic Trouble Codes).
    Throttle Body with Motor Assembly Upon receiving signals from the ECM, the throttle control motor actuates the throttle valve.
    Driving Support ECU Assembly While the system is in vehicle-to-vehicle distance control mode, the driving support ECU assembly detects vehicles in front based on signals from the millimeter wave radar sensor assembly. Then, the driving support ECU assembly calculates the acceleration or deceleration required in order to attain the target vehicle-to-vehicle distance, and outputs request signals to the ECM and skid control ECU (brake actuator assembly).

  3. LIMIT CONTROL


    1. Low speed limit


      • The lowest possible set speed is approximately 50 km/h (31 mph). The dynamic radar cruise control system cannot be set when the vehicle speed is below the low speed limit.

      • When the vehicle speed is below approximately 40 km/h (25 mph), the dynamic radar cruise control system will be automatically canceled but the stored vehicle speed will be retained.

    2. High speed limit (constant speed control mode)

      The highest possible set speed is approximately 200 km/h (125 mph). The dynamic radar cruise control system will be set at the high speed limit when the cruise control is set and the vehicle speed is over the high speed limit. Also, +/RES cannot be used to increase the speed beyond the high speed limit.

    3. High speed limit (vehicle-to-vehicle distance control mode)

      The highest possible set speed is approximately 170 km/h (105 mph). The dynamic radar cruise control system will be set at the high speed limit when the cruise control is set and the vehicle speed is over the high speed limit. Also, +/RES cannot be used to increase the speed beyond the high speed limit.

  4. OPERATION OF CRUISE CONTROL

    The cruise control main switch is used to turn the dynamic radar cruise control system on and off, as well as operate 8 functions: SET, - (COAST), TAP-DOWN, RES (RESUME), + (ACCEL), TAP-UP, CANCEL, and MODE. The SET, TAP-DOWN and - (COAST) functions, and the RES (RESUME), TAP-UP, and + (ACCEL) functions are operated with the same switch. The cruise control main switch is an automatic return type switch which turns on only operating it in the direction of each arrow and turns off when it is released. The dynamic radar cruise control system has 2 cruise control modes: constant speed control mode and vehicle-to-vehicle distance control mode.


    • A01HZZ5E01
      Text in Illustration
      *a

      Cruise Control Indicator

      (Vehicle-to-vehicle distance control mode)
      *b Multi-information Display

      Vehicle-to-vehicle distance control mode is selected by default when the dynamic radar cruise control system is turned on, and the cruise control indicator (vehicle-to-vehicle distance control mode) illuminates and "Radar ready" is displayed on the multi-information display.

    • Operation of constant speed control mode is the same as that for a conventional cruise control system.


    1. A01I02GE01
      Text in Illustration
      *a

      Cruise Control Indicator

      (Constant speed control mode)

      MODE CONTROL

      Pushing the switch to MODE for more than 1 second while vehicle-to-vehicle distance control mode is ready switches the dynamic radar cruise control system to constant speed control mode. The cruise control indicator (constant speed control mode) will illuminate.

    2. A01HZ07E09
      Text in Illustration
      *a

      Cruise Control Indicator

      (Constant speed control mode)
      *b Cruise Control SET Indicator

      SET CONTROL (Constant speed control mode)

      The vehicle speed is stored and constant speed control mode begins controlling vehicle speed when the cruise control main switch is pushed to -/SET while driving with the dynamic radar cruise control system on, and the vehicle speed is over the low speed limit after entering constant speed control mode. The cruise control SET indicator will illuminate, and set speed will be displayed on the multi-information display.

    3. A01I0PGE03
      Text in Illustration
      *a

      Cruise Control Indicator

      (Vehicle-to-vehicle distance control mode)
      *b Cruise Control SET Indicator

      SET CONTROL (Vehicle-to-vehicle distance control mode)

      The vehicle speed is stored and vehicle-to-vehicle distance control mode begins controlling vehicle speed when the cruise control main switch is pushed to -/SET while driving with the dynamic radar cruise control system on, and the vehicle speed is over the low speed limit. The cruise control SET indicator will illuminate, and set speed will be displayed on the multi-information display.

    4. - (COAST) CONTROL (Constant speed control mode)

      When the cruise control main switch is pushed to - SET and held in that position while the dynamic radar cruise control system is operating, the ECM sends a "throttle valve opening angle 0°" demand signal to the dynamic radar cruise control system. Then the vehicle speed, when the cruise control main switch is released, is stored and maintained.

    5. (COAST) CONTROL (Vehicle-to-vehicle distance control mode)

      When vehicle-to-vehicle distance control mode is controlling vehicle speed and the cruise control main switch is pushed to -/SET and held in that position, the stored vehicle speed decreases by approximately 5 km/h or 5 mph.

    6. TAP-DOWN (CONTROL) (Constant speed control mode)

      When constant speed control mode is controlling vehicle speed and the cruise control main switch is tapped to -/SET (for approximately 0.6 seconds or less), the stored vehicle speed decreases by approximately 1 km/h (1 mph) for each time the switch is tapped. When the cruise control main switch is released from -/SET and the difference between the current and stored vehicle speed is more than approximately 5 km/h (3 mph), the current vehicle speed is stored and maintained.

    7. TAP-DOWN CONTROL (Vehicle-to-vehicle distance control mode)

      When vehicle-to-vehicle distance control mode is controlling vehicle speed and the cruise control main switch is tapped to -/SET (for approximately 0.6 seconds or less), the stored vehicle speed decreases by approximately 1 km/h or 1 mph for each time the switch is tapped.

    8. + (ACCEL) CONTROL (Constant speed control mode)

      When constant speed control mode is controlling vehicle speed and the cruise control main switch is pushed to +/RES and held in that position, the sensor and motor is instructed by the ECM to open the throttle valve. When the cruise control main switch is released from + RES, the vehicle speed is stored and constant speed control is maintained.

    9. + (ACCEL) CONTROL (Vehicle-to-vehicle distance control mode)

      When vehicle-to-vehicle distance control mode is controlling vehicle speed and the cruise control main switch is pushed to +/RES and held in that position, the stored vehicle speed increases by approximately 5 km/h or 5 mph. Pushing the cruise control main switch to +/RES while following a vehicle in front using vehicle-to-vehicle distance control mode does not increase actual vehicle speed, but changes only the set speed.

    10. TAP-UP CONTROL (Constant speed control mode)

      When constant speed control mode is controlling vehicle speed and the cruise control main switch is tapped to +/RES (for approximately 0.6 seconds or less), the stored vehicle speed increases by approximately 1 km/h (1 mph) for each time the switch is tapped. When the cruise control main switch is released from +/RES and the difference between the current and stored vehicle speed is more than approximately 5 km/h (3 mph), the stored vehicle speed will not be changed.

    11. TAP-UP CONTROL (Vehicle-to-vehicle distance control mode)

      When vehicle-to-vehicle distance control mode is controlling vehicle speed and the cruise control main switch is tapped to +/RES (for approximately 0.6 seconds or less), the stored vehicle speed increases by approximately 1 km/h or 1 mph for each time the switch is tapped.

    12. MANUAL CANCEL CONTROL

      Performing any of the following cancels dynamic radar cruise control system control of vehicle speed (the stored vehicle speed in the driving support ECU assembly is maintained).


      • Depressing the brake pedal.

      • Moving the shift lever from D or S to any other position.

      • Selecting the 3rd, 2nd, or 1st range with the shift lever in S.

      • Selecting the 3rd, 2nd or 1st range using the shift paddle switch assembly with the shift lever in D or S.*

      • Pulling the cruise control main switch to CANCEL.

      • Turning the dynamic radar cruise control system off using the cruise control main switch (ON-OFF button) (the stored vehicle speed in the ECM is not maintained).


      • *: w/ Shift Paddle Switch

    13. RES (RESUME) CONTROL

      If control of vehicle speed by the dynamic radar cruise control system was canceled by the stop light switch assembly, CANCEL switch, or shift lever operation, and if vehicle speed is between the low and high speed limits, pushing the cruise control main switch to +/RES restores and maintains the stored vehicle speed from the time of cancellation. In constant speed control mode, once the vehicle speed drops below the low speed limit, RESUME operation is possible after accelerating past the low speed limit and pushing the cruise control main switch to +/RES.

  5. BRAKE CONTROL

    The driving support ECU assembly determines the distance to the vehicle in front, relative speed, target speed reduction, and deceleration rate. Based on this data, the ECU transmits a brake demand signal to the skid control ECU (brake actuator assembly) via the ECM.

  6. DOWN SHIFT CONTROL

    While the dynamic radar cruise control system is operating, the transaxle may downshift from an overdrive gear on an uphill road. After the downshift, if the system determines that the uphill inclination has become smaller based on the throttle valve opening angle, the transaxle automatically returns to the overdrive gear.

  7. AUTO CANCEL (FAIL-SAFE)

    This system has an automatic cancellation function (fail-safe) Click here.