System Description [01/2017 - 05/2023]

GENERAL

The cruise control main switch is used to turn the dynamic radar cruise control system on and off, as well as operate 7 functions: SET, - (COAST), TAP-DOWN, RES (RESUME), + (ACCEL), TAP-UP and CANCEL. The SET, TAP-DOWN, and - (COAST) functions, and the RES (RESUME), TAP-UP, and + (ACCEL) functions are operated with the same switch.

HINT:

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 selected by default when the dynamic radar cruise control system is turned on using the cruise control main switch.
Operation of constant speed control mode is the same as that for a conventional cruise control system.

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 skid control ECU assembly 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.
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.
The millimeter wave radar sensor assembly, forward recognition camera and driving support ECU assembly control the system while vehicle-to-vehicle distance control mode is operating, and send signals to each actuator and ECU.
In vehicle-to-vehicle distance control mode, the dynamic radar cruise control system receives signals from the forward recognition camera, yaw rate sensor and the steering 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.
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 assembly and forward recognition camera 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.

The dynamic radar cruise control system performs the following controls (example).

HINT:

Vehicle distance increases and decreases in accordance with vehicle speed.
Control conditions are indicated on the multi-information display in the combination meter assembly.

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

*1	Drives the vehicle at a constant speed (set speed: 100 km/h (60 mph))	*2	Decelerates the vehicle from the set speed to the speed of the preceding vehicle (80 km/h (50 mph))*
*3	Follows the preceding vehicle while maintaining an appropriate vehicle-to-vehicle distance according to the speed of the preceding vehicle	*4	Gradually accelerates the vehicle to the set speed and maintains the speed
*5	Decelerates and stops the vehicle while maintaining an appropriate distance with the preceding vehicle	*6	Maintains the vehicle stopped in conjunction with the brake hold function
*7	When the +RES switch is pushed or the accelerator pedal is depressed after the preceding vehicle starts off, follow-up control is resumed	*8	If a preceding vehicle is not detected when the vehicle speed is approximately 40 km/h (25 mph) or less, control is canceled

*: Throttle valve control and brake control are performed to decelerate the vehicle. If deceleration is insufficient and the distance to the preceding vehicle becomes too short, the vehicle approach warning buzzer sounds to warn the driver to take an appropriate action (braking, etc.).

FUNCTION OF MAIN COMPONENTS

The main components of the dynamic radar cruise control system have the following functions:

Component		Outline
Combination Meter Assembly	Cruise Control Indicator (Vehicle-to-vehicle Distance Control Mode)	Illuminates based on signals from the hybrid vehicle control ECU assembly when the dynamic radar cruise control system is turned on using the cruise control main switch. Turns off based on signals from the hybrid vehicle control ECU assembly or driving support ECU when a malfunction is detected in the dynamic radar cruise control system.
	Cruise Control Indicator (Constant Speed Control Mode)	Illuminates when the dynamic radar cruise control system is turned on using the cruise control main switch and constant speed control mode is selected.
	Cruise Control SET Indicator	Illuminates when the vehicle speed is set.
	Multi-information Display	Displays dynamic radar cruise control system information based on signals from the hybrid vehicle control ECU assembly when the dynamic radar cruise control system is turned on using the cruise control main switch. Displays a warning message if the hybrid vehicle control ECU assembly or driving support ECU assembly detects a malfunction signal while the dynamic radar cruise control system is controlling vehicle speed.
	Warning Buzzer	Sounds once to inform the driver if the hybrid vehicle control ECU assembly or driving support ECU assembly detects an automatic cancel signal while the dynamic radar cruise control system is controlling vehicle speed.
Steering Pad Switch Assembly	Cruise Control Main Switch	Turns the dynamic radar cruise control system on and off. Switches the control mode between constant speed control mode and vehicle-to-vehicle distance control mode.
	CANCEL Switch	A cancel signal is sent to the hybrid vehicle control ECU assembly when the switch is operated.
	+RES Switch	Acceleration and stored speed resume signals are sent to the hybrid vehicle control ECU assembly when the switch is operated.
	-SET Switch	Deceleration and vehicle speed setting signals are sent to the hybrid vehicle control ECU assembly when the switch is operated.
	Vehicle-to-vehicle Distance Control Switch	When vehicle-to-vehicle distance control mode is controlling vehicle speed, the driver can operate the switch to select the vehicle-to-vehicle distance in 3 stages: long, middle, and short.
Stop Light Switch Assembly		Outputs brake pedal depression signals to the hybrid vehicle control ECU assembly.
Millimeter Wave Radar Sensor Assembly		Sends information such as vehicle-to-vehicle distance, relative speed and presence of a vehicle in front to the driving support ECU assembly based on reflected millimeter waves.
Forward Recognition Camera		Captures the image in front of the vehicle to detect lane markers and objects on the road ahead.
Steering Sensor		Outputs steering angle signals to the driving support ECU assembly.
Speed Sensor		Outputs wheel speed signals to the skid control ECU assembly.
Yaw Rate Sensor		Outputs yaw rate signals to the driving support ECU assembly.
Skid Control ECU Assembly		Operates the brake actuator assembly in accordance with brake request signals received from the hybrid vehicle control ECU assembly when the dynamic radar cruise control system is in vehicle-to-vehicle distance control mode. The skid control ECU assembly is illuminates the stop lights by operating the No. 3 semiconductor power integration ECU.
Pre-collision City Buzzer		Sounds upon receiving signals from the driving support ECU assembly.
Hybrid Vehicle Control ECU Assembly		Controls the dynamic radar cruise control system in accordance with signals received from switches, sensors, and the driving support ECU assembly. Stores DTCs if a malfunction is detected in the dynamic radar cruise control system.
Throttle with Motor Body Assembly		Adjusts the throttle valve opening angle in accordance with signals received from the ECM.
Driving Support ECU Assembly		Detects a preceding vehicle based on signals from the millimeter wave radar sensor assembly when the dynamic radar cruise control system is in vehicle-to-vehicle distance control mode. Then, the driving support ECU assembly calculates the acceleration or deceleration required to achieve the target vehicle-to-vehicle distance, and outputs request signals to the hybrid vehicle control ECU assembly. Stores DTCs if a malfunction is detected in the dynamic radar cruise control system.
Transmission Floor Shift Assembly		Outputs the shift lever position to the shift control ECU.
VSC OFF Switch (No. 2 Combination Switch Assembly)		Outputs VSC off signals to the skid control ECU assembly.
Shift Control ECU		While the vehicle is being driven in S mode, outputs "+" (upshift) or "-" (downshift) request signals to the hybrid vehicle control ECU assembly.
Parking Brake ECU Assembly		Operates the parking brake actuator when control of vehicle speed by the dynamic radar cruise control system is canceled with the vehicle stopped.
Electric Parking Brake Switch Assembly		Detects operation of the electric parking brake and cancels control of vehicle speed by the dynamic radar cruise control system.
Parking Brake with Bracket Actuator Assembly		Operates the parking brake actuator according to signals from the parking brake ECU assembly.

OPERATION OF DYNAMIC RADAR CRUISE CONTROL

Controls performed by the dynamic radar cruise control system in each control mode (constant speed control mode and vehicle-to-vehicle distance control mode) are as follows:

Mode	Outline
Constant Speed Control Mode	Mode that maintains a constant vehicle running speed according to the set vehicle speed.
Vehicle-to-vehicle Distance Control Mode	Mode that performs tracking from stop to start and at all vehicle speed range while maintaining an appropriate vehicle-to-vehicle distance by recognizing and determining the driving lane between the preceding vehicle and own vehicle.

Vehicle-to-vehicle Distance Control Mode:

Function	Outline
Set Control	The vehicle speed is stored and control of vehicle speed begins when the -SET switch is pushed while driving at a speed of between approximately 50 km/h (31 mph) or more with the dynamic radar cruise control system on. The lowest possible set speed is stored and follow-up control begins when the -SET switch is pushed to while driving behind a vehicle at a speed less than approximately 50 km/h (31 mph) with the dynamic radar cruise control system on. When the set speed is stored, the cruise control SET indicator illuminates and the set speed is displayed on the multi-information display.
Low Speed Limit Control	The low speed limit is approximately 40 km/h (25 mph). If the vehicle speed drops below the low speed limit, speed control by the dynamic radar cruise control system is canceled automatically and the set vehicle speed is kept in memory. The lowest possible set speed is approximately 50 km/h (31 mph).
Constant Speed Control	The driving support ECU assembly compares the actual vehicle speed and the stored vehicle speed. When the vehicle speed is less than the stored vehicle speed, it increases the opening angle of the throttle valve.
Follow-up Control	The vehicle follows the preceding vehicle while maintaining an appropriate vehicle-to-vehicle distance according to the speed of the preceding vehicle.
Stop Control	When the preceding vehicle stops, motive force control is performed to stop the vehicle while maintaining an appropriate vehicle-to-vehicle distance.
Stop Retention Control	After the vehicle has stopped by stop control, the driving support ECU assembly outputs a stop retention request signal to the skid control ECU assembly. Upon receiving this signal, the skid control ECU assembly operates the brake hold function to keep the vehicle stationary.
Start Control	When the driving support ECU assembly determines that the preceding vehicle has started off based on a signal received from the millimeter wave radar sensor, it displays the messages "Push Cruise Control Switch or Press Accelerator to Resume" on the multi-information display to inform the driver to perform the start-off operation (push the +RES switch or depress the accelerator pedal). When the start-off operation is performed, the driving support ECU assembly sends a motive force request signal to the hybrid vehicle control ECU assembly. Upon receiving the signal, the hybrid vehicle control ECU assembly controls the motive force, starts off the vehicle and resumes follow-up control.
Mode Control	When the cruise control main switch is pushed and held for 1.5 seconds or more with the dynamic radar cruise control system off, mode changes to constant speed control mode.
+ (ACCEL) Control	When the dynamic radar cruise control system is controlling vehicle speed and the +RES switch is pushed and held, the dynamic radar cruise control system sends a signal to the hybrid vehicle control ECU assembly to operate the throttle valve motor of the throttle body with motor assembly to open the throttle valve. Following this, the vehicle speed is stored and maintained when the +RES switch is released. Pushing the +RES switch while following a preceding vehicle using vehicle-to-vehicle distance control mode does not increase actual vehicle speed, but changes only the stored vehicle speed.
Tap-up Control	When vehicle-to-vehicle distance control mode is controlling vehicle speed and the +RES switch is tapped (for 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.
- (COAST) Control	When vehicle-to-vehicle distance control mode is controlling vehicle speed and the -SET switch is pushed and held in that position, the stored vehicle speed decreases.
TAP-DOWN Control	When vehicle-to-vehicle distance control mode is controlling vehicle speed and the -SET switch is tapped (for 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.
Auto Cancel Control	This system has an automatic cancellation function (fail-safe). Refer to FAIL-SAFE CHART [01/2017 - 05/2023]
Manual Cancel Control	Performing any of the following cancels dynamic radar cruise control system control of vehicle speed (the stored vehicle speed in the hybrid vehicle control ECU assembly is maintained). Depressing the brake pedal. Moving the shift position from D to any other position. Pushing the CANCEL switch. Turning the dynamic radar cruise control system off using the cruise control main switch (the stored vehicle speed in the hybrid vehicle control ECU assembly is not maintained). Electric parking brake is applied.
Other Control Cancellation Conditions	For details of other cancel controls, refer to the fail-safe chart. Refer to FAIL-SAFE CHART [01/2017 - 05/2023]
RES (Resume) Control	If control of vehicle speed by the dynamic radar cruise control system was canceled due to any of the manual cancel conditions (other than turning the dynamic radar cruise control system off using the cruise control main switch), and if the vehicle speed is approximately 40 km/h (25 mph) or more, the stored vehicle speed from the time of cancellation will be resumed and maintained when the +RES switch is pushed. If the preceding vehicle moves out of the lane while follow-up control is operating, the vehicle speed is gradually increased to the set vehicle speed. At this time, the vehicle speed can be increased by pushing the +RES switch. After the preceding vehicle starts off, a message is displayed to inform the driver to perform the start-off operation. When the +RES switch is pushed, follow-up control is resumed and the vehicle is accelerated up to the set speed.
Brake Control	When a large amount of deceleration is required while vehicle-to-vehicle distance control mode is controlling vehicle speed, the brake actuator assembly is operated to apply the brakes. The stop lights illuminate at this time.

Constant Speed Control Mode:

Function	Outline
Constant Speed Control	The driving support ECU assembly compares the actual vehicle speed and the stored vehicle speed. When the vehicle speed is less than the stored vehicle speed, it increases the opening angle of the throttle valve.
Set Control	The vehicle speed is stored and control of vehicle speed begins when the -SET switch is pushed while driving at a speed of between approximately 40 km/h (25 mph) or more with the dynamic radar cruise control system on. When the set speed is stored, the cruise control SET indicator illuminates and the set speed is displayed on the multi-information display.
Low Speed Limit Control	The low speed limit is approximately 40 km/h (25 mph). If the vehicle speed drops below the low speed limit, speed control by the dynamic radar cruise control system is canceled automatically. The lowest possible set speed is approximately 40 km/h (25 mph).
+ (ACCEL) Control	When the dynamic radar cruise control system is controlling vehicle speed and the +RES switch is pushed and held, the cruise control system sends a signal to the hybrid vehicle control ECU assembly to operate the throttle valve motor of the throttle body with motor assembly to open the throttle valve. Following this, the vehicle speed is stored and maintained when the +RES switch is released.
Tap-up Control	When the dynamic radar cruise control system is controlling vehicle speed and the cruise control main switch is tapped to +RES (for approximately 0.6 seconds), the stored vehicle speed increases by approximately 1 km/h or 1 mph for each time the switch is tapped. When the cruise control main switch is tapped to +RES and the difference between the current and stored vehicle speed is more than 5 km/h (3 mph), the stored vehicle speed will not be changed.
- (COAST) Control	When the dynamic radar cruise control system is controlling vehicle speed and the -SET switch is pushed and held in that position, the stored vehicle speed decreases. HINT: An actual throttle valve opening angle of 0° is not possible due to factors such as idle speed control.
Tap-down Control	When the dynamic radar cruise control system is controlling vehicle speed and the -SET switch is tapped (for approximately 0.6 seconds), the stored vehicle speed decreases by approximately 1 km/h or 1 mph for each time the switch is tapped. When the cruise control main switch is tapped to -SET and the difference between the current and stored vehicle speed is more than 5 km/h (3 mph), the current vehicle speed is stored and speed control is performed.
Auto Cancel Control	This system has an automatic cancellation function (fail-safe). Refer to FAIL-SAFE CHART [01/2017 - 05/2023]
Manual Cancel Control	Performing any of the following cancels dynamic radar cruise control system control of vehicle speed. Depressing the brake pedal. Moving the shift position from D to any other position. Pushing the CANCEL switch. Turning the cruise control system off using the cruise control main switch (the stored vehicle speed in the hybrid vehicle control ECU assembly is not maintained).
Other Control Cancellation Conditions	For details of other cancel controls, refer to the fail-safe chart. Refer to FAIL-SAFE CHART [01/2017 - 05/2023]
RES (Resume) Control	If control of vehicle speed by the dynamic radar cruise control system was canceled due to any of the manual cancel conditions (other than turning the dynamic radar cruise control system off using the cruise control main switch), and if the vehicle speed is approximately 40 km/h (25 mph) or more, the stored vehicle speed from the time of cancellation will be resumed and maintained when the +RES switch is pushed.