Dynamic Radar Cruise Control System

CRUISE CONTROL: DYNAMIC RADAR CRUISE CONTROL SYSTEM: SYSTEM DIAGRAM

Communication Table

SYSTEM DESCRIPTION

1. GENERAL

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

The vehicle-to-vehicle distance control mode is always selected when starting the dynamic radar cruise control system.

Operation of the constant speed control mode is the same as the conventional cruise control system.

(b) If there is a vehicle ahead in the same lane, the system maintains the 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 closes the throttle valve to decelerate. 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 vehicle speed and resumes driving at the constant speed.

(c) The constant speed control mode is designed to maintain a constant cruising speed. The vehicle-to-vehicle distance control mode is designed to control cruising using a constant speed function, deceleration cruising function, follow-up cruising function and acceleration cruising function.

(d) The millimeter wave radar sensor assembly and driving support ECU control the system while the vehicle-to-vehicle distance control mode is in operation and send signals to each actuator and ECU.

(e) In vehicle-to-vehicle distance control mode, the dynamic radar cruise control system receives signals from the yaw rate sensor and steering angle sensor. Based on these signals, it then estimates curve radius and corrects the information on the preceding vehicle while turning. It can also adjust the brake control when approaching another vehicle.

(f) This system judges the presence of a vehicle in front and the distance to it based on the signals from the millimeter wave radar sensor while the vehicle-to-vehicle distance control mode is in operation. Using this information, the system informs the driver of any danger with the warning buzzer, performs brake control and turns on the stop light when approaching the vehicle in front.

(g) The following illustration shows an example under the following conditions: the 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 setting can be changed to 3 distances by operating the steering pad switch (distance control switch): long (approximately 50 m [160 ft.]), middle (approximately 40 m [130 ft.]) and short (approximately 30 m [100 ft.]) (when the vehicle speed is approximately 80 km/h [50 mph]).

HINT
* Vehicle distance increases and decreases in accordance with vehicle speed.
* The controlling condition is indicated on the multi-information display in the combination meter assembly.

2. FUNCTION OF MAIN COMPONENTS

3. LIMIT CONTROL

(a) Low speed limit

The lower limit of the speed setting range is set at approximately 50 km/h (30 mph). The cruise control system cannot be set when the driving vehicle speed is below the low speed limit. Cruise control operation is automatically canceled when the vehicle speed decreases below the low speed limit (40 km/h [25 mph]) while the cruise control system is in operation. When the vehicle speed is increased above the low speed limit after the cruise control operation is canceled, pressing the +RES switch increases the vehicle speed to the stored speed.

(b) High speed limit (Constant speed control mode)

The upper limit of the speed setting range is approximately 200 km/h (125 mph). The cruise control system cannot be set when the driving vehicle speed is over the high speed limit. Also, RESUME/ACCEL cannot be used to increase speed beyond the high speed limit.

(c) High speed limit (Vehicle-to-vehicle distance control mode)

The upper limit of the speed setting range is approximately 170 km/h (105 mph). The cruise control system cannot be set when the driving vehicle speed is over the high speed limit. Also, RESUME/ACCEL cannot be used to increase speed beyond the high speed limit.

4. CRUISE CONTROL OPERATION

The cruise control switch operates 8 functions: SET, COAST, TAP-DOWN, RESUME, ACCEL, TAP-UP, CANCEL and MODE. The SET, TAP-DOWN and COAST functions and the RESUME, TAP-UP and ACCEL functions are operated with the same switch. The cruise control switch is an automatic return type switch which turns on only while pushing it in each arrow direction and turns off after releasing it. The dynamic radar cruise control system has two cruise control modes: constant speed control mode and vehicle-to-vehicle distance control mode.

The vehicle-to-vehicle distance control mode is always selected when starting up the dynamic radar cruise control system (the cruise control indicator light and RADAR READY turn on).

Text in Illustration

Operation of the constant speed control mode is the same as the conventional cruise control system.

(a) MODE CONTROL

Pushing the cruise control switch to MODE for more than 1 second while driving in vehicle-to-vehicle distance control mode (RADAR READY is on) switches the dynamic radar cruise control system to the constant speed control mode.

(b) SET CONTROL (Constant speed control mode)

The vehicle speed is stored and constant speed control is maintained when pushing the cruise control switch to -SET while driving with the vehicle speed within the set speed range (between the low and high speed limits) after pushing the cruise control switch on and entering the constant speed control mode (the cruise control indicator light and SET indicator light turn on).

Text in Illustration

The vehicle speed is stored and vehicle-to-vehicle control is maintained when pushing the cruise control switch to -SET while driving with the cruise control switch on (RADAR READY is on) and with the vehicle speed within the set speed range (between the low and high speed limits) (the cruise control indicator light and SET indicator light turn on).

Text in Illustration

(d) COAST CONTROL (Constant speed control mode)

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

(e) COAST CONTROL (Vehicle-to-vehicle distance control mode)

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

(f) TAP-DOWN CONTROL (Constant speed control mode)

When tapping down the cruise control switch to -SET (for approximately 0.6 seconds) while the constant speed control mode is in operation, the stored vehicle speed decreases by approximately 1.6 km/h (1 mph). When the cruise control switch is pushed to -SET and the difference between the driving and stored vehicle speed is more than 5 km/h (3 mph), the vehicle speed is stored and constant speed control is maintained.

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

When tapping down the cruise control switch to -SET (for approximately 0.6 seconds) while the vehicle-to-vehicle distance control mode is in operation, the stored vehicle speed decreases by approximately 1 km/h or 1 mph.

(h) ACCELERATION CONTROL (Constant speed control mode)

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

(i) ACCELERATION CONTROL (Vehicle-to-vehicle distance control mode)

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

(j) TAP-UP CONTROL (Constant speed control mode)

When tapping up the cruise control switch to +RES (for approximately 0.6 seconds) while the constant speed control mode is in operation, the stored vehicle speed increases by approximately 1.6 km/h (1 mph). However, when the difference between the driving and the stored vehicle speeds is more than 5 km/h (3 mph), the stored vehicle speed is not changed.

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

When tapping up the cruise control switch to +RES (for approximately 0.6 seconds) while the vehicle-to-vehicle distance control mode is in operation, the stored vehicle speed increases by approximately 1 km/h or 1 mph.

(l) SHIFT DOWN CONTROL

Overdrive may be canceled automatically when using cruise control while driving on inclined roads, etc.

After overdrive is canceled, if the system determines that the road is no longer inclined based on the fuel injection volume opening amount, overdrive is restored.

If overdrive is canceled during an ACCEL or RESUME operation, overdrive is restored after the ACCEL or RESUME operation is completed.

(m) MANUAL CANCEL CONTROL

Performing any of the following cancels cruise control while it is in operation (the stored vehicle speed in the ECM is maintained).

Depressing the brake pedal

Moving the shift lever from D to N, or selecting 3rd, 2nd or 1st range with the shift lever in S

Driving the vehicle while the vehicle stability control system is operating

When the ECM detects a cruise control cancel signal from the four wheel drive control ECU

Pulling the cruise control switch to CANCEL

Pushing the cruise control switch off (the stored vehicle speed in the ECM is not maintained)

(n) RES (RESUME) CONTROL

If cruise control operation is canceled with the stop light switch, CANCEL switch, etc., and if the driving speed is within the set speed range, pushing the cruise control switch to +RES restores the vehicle speed memorized at the time of cancellation, and initiates constant speed control.

Vehicle-to-vehicle distance control mode

When the vehicle-to-vehicle distance control mode is operating, if the vehicle in front changes lanes, your vehicle changes lanes, or another situation occurs so that there is no vehicle in front, the vehicle speed automatically increases slowly to the stored vehicle speed. At this time, if the +RES switch is pressed, the vehicle speed increases quickly to the stored vehicle speed.

5. BRAKE CONTROL

The driving support ECU determines the distance to the vehicle in front, relative speed, target decreasing speed and deceleration rate. Based on this data, the ECU may transmit a brake demand signal to the skid control ECU.

6. AUTO CANCEL (FAIL-SAFE)

This system has an automatic cancellation function (fail-safe) Fail-Safe Chart.