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 two cruise control modes: constant speed control mode and vehicle-to-vehicle distance control mode.
* Vehicle-to-vehicle distance control mode is always selected when starting the dynamic radar cruise control system.
* Operation of constant speed control mode is the same as that for a conventional cruise control system.
(b) This system maintains the vehicle at the speed that the driver has set, as long as there are no vehicles ahead. Then, 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 controls the engine and motor driving force 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 vehicle speed and resumes driving at the constant speed.
(c) Constant speed control mode is designed to maintain a constant cruising speed. Vehicle-to-vehicle distance control mode is designed to control cruising at a constant speed function, deceleration cruising function, follow-up cruising function, and acceleration cruising function.
(d) The millimeter wave radar sensor 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.
(e) 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.
(f) 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.
(g) 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). Setting of the vehicle distance can be changed to 3 distances by operating the distance control 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.
* 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 lowest possible set speed is approximately 40 km/h (25 mph). The cruise control system cannot be set when the driving vehicle speed is below the low speed limit. Cruise control operation will be automatically canceled when the vehicle speed decreases below the low speed limit of approximately 40 km/h (25 mph) while the cruise control is operating.
(b) High speed limit (constant speed control mode)
The highest possible set speed is approximately 200 km/h (125 mph). The 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 speed over the high speed limit.
(c) High speed limit (vehicle-to-vehicle distance control mode)
The highest possible set speed is approximately 170 km/h (105 mph).
4. CRUISE CONTROL OPERATION
The cruise control switch operates 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 switch is an automatic return type switch which turns on only while operating it in the direction of each arrow 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.
* Vehicle-to-vehicle distance control mode is always selected when starting up the dynamic radar cruise control system (the cruise control indicator light comes on and "RADAR READY" is displayed on the multi-information display).
Text in Illustration
* Operation of constant speed control mode is the same as that for a conventional cruise control system.
(a) MODE CONTROL
Pushing the switch to MODE for more than 1 second while vehicle-to-vehicle distance control mode is ready ("RADAR READY" is on) switches the cruise control system to 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 switch to -/SET while driving with the vehicle speed within the set speed range (the minimum set speed or faster) after pushing the cruise control switch (ON-OFF button) on, and entering constant speed control mode (the cruise control indicator light comes on and cruise control SET indication and the cruise control set speed are displayed on the multi-information display).
Text in Illustration
(c) SET CONTROL (Vehicle-to-vehicle distance control mode)
The vehicle speed is stored and vehicle-to-vehicle distance control is maintained when pushing the cruise control switch to -/SET while driving with the cruise control switch (ON-OFF button) on ("RADAR READY" is on), and vehicle speed is within the set speed range (the minimum set speed or faster) (the cruise control indicator light comes on and cruise control SET indication and the cruise control set speed are displayed on the multi-information display).
Text in Illustration
(d) - (COAST) CONTROL (Constant speed control mode)
The power management control ECU decreases the cruise control demand speed and controls the engine and motor driving force to decelerate the vehicle when -/SET on the cruise control switch is pressed and held while the cruise control system is operating. When the cruise control switch is released from -/SET, vehicle speed is stored and constant speed control is maintained.
(e) - (COAST) CONTROL (Vehicle-to-vehicle distance control mode)
When the cruise control switch is held to -/SET while the cruise control system is operating, the stored vehicle speed decreases by approximately 5 km/h (5 mph).
(f) TAP-DOWN (CONTROL) (Constant speed control mode)
When tapping down the cruise control switch to -/SET (for 0.6 seconds or less) while the constant speed control mode is operating, the stored vehicle speed decreases each time by approximately 1.6 km/h (1 mph). When the cruise control switch is released from -/SET and the difference between the driving and stored vehicle speeds is more than approximately 5 km/h (3 mph), the driving 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 0.6 seconds or less) while the vehicle-to-vehicle distance control mode is operating, the stored vehicle speed decreases each time by approximately 1 km/h (1 mph).
(h) + (ACCEL) CONTROL (Constant speed control mode)
The power management control ECU increases the cruise control demand speed and controls the engine and motor driving force to accelerate the vehicle when +/RES on the cruise control switch is pressed and held while the cruise control system is operating.
When the cruise control switch is released from +/RES, vehicle speed is stored and constant speed control is maintained.
(i) + (ACCEL) CONTROL (Vehicle-to-vehicle distance control mode)
When +/RES on the cruise control switch is pressed and held while vehicle-to-vehicle distance control mode is operating, the stored vehicle speed increases by approximately 5 km/h (5 mph). Pushing the cruise control switch to +/RES while following the vehicle in front with the vehicle-to-vehicle distance control mode 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 0.6 seconds or less) while the constant speed control mode is operating, the stored vehicle speed increases each time by approximately 1.6 km/h (1 mph). However, when the difference between the driving and the stored vehicle speeds is more than approximately 5 km/h (3 mph), the stored vehicle speed will not be changed.
(k) TAP-UP CONTROL (Vehicle-to-vehicle distance control mode)
When tapping up the cruise control switch to +/RES (for 0.6 seconds or less) while vehicle-to-vehicle distance control mode is operating, the stored vehicle speed increases each time by approximately 1 km/h (1 mph).
(l) MANUAL CANCEL CONTROL
Performing any of the following cancels the cruise control system while it is operating (the stored vehicle speed in the driving support ECU assembly is maintained).
* Depressing the brake pedal
* Moving the shift lever from D to any other position
* Pushing the cruise control switch to CANCEL
* Turning the cruise control switch off (the stored vehicle speed in the driving support ECU assembly is not maintained)
(m) RES (RESUME) CONTROL
If the cruise control operation was canceled by the stop light switch, CANCEL switch, or shift lever operation, and if 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 maintains constant speed control. 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 switch to +/RES.
5. BRAKE CONTROL
The driving support ECU assembly determines the distance to the vehicle in front, relative speed, target decreasing speed, and deceleration rate. Based on this data, the ECU transmits a brake demand signal to the brake booster with master cylinder (skid control ECU) via the driving support ECU assembly.
6. AUTO CANCEL (FAIL-SAFE)
This system has an automatic cancellation function (fail-safe) Fail-Safe Chart.