ROAD SIGN ASSIST SYSTEM

FUNCTION OF MAIN COMPONENTS

1. The main components in the RSA have the following functions.

   Components		Function
   Camera Sensor (Forward Recognition Camera)*1		Captures road signs. Performs RSA system control based on information of road signs captured. Sends an operation signal to the camera heater.
   Camera Sensor (Object Recognition Camera)*2
   Camera Heater (Forward Recognition Hood with Heater Sub-assembly)		The camera heater is heated according to signals from the camera sensor.
   Millimeter Wave Radar Sensor Assembly		Detects object information and sends a signal to the camera sensor.
   Hybrid Vehicle Control ECU Assembly		Sends the shift position signal to the camera sensor.
   Skid Control ECU Assembly		Sends a vehicle speed signal to the camera sensor.
   Combination Meter Assembly		Sends a turn signal command to the camera sensor.
   Combination Meter Assembly	Multi-information Display	Displays road signs recognized by the camera sensor. The RSA system can be turned on and off through the settings tab.
   	Master Warning Indicator	Illuminates when there is a malfunction in the RSA system.
   	Meter Buzzer	Sounds when the speed limit is exceeded*3 or there is an entry prohibition notification.
   Yawrate Sensor		Detects the yaw rate and sends it to the camera sensor.
   Steering Sensor		Sends the turning angle of the steering wheel to the camera sensor. Sends a turn signal command to the combination meter assembly.
   Turn Signal Switch		Sends a turn signal command to the steering sensor.
   Headup Display (Meter Mirror Sub-assembly)*4		Displays road signs recognized by the camera sensor.
   Radio Receiver Assembly*5		Sends map information from the navigation ECU to the camera sensor.
   Navigation ECU*5		Sends map information to the radio receiver assembly. Performs coordinated control with the camera sensor in regards to speed limit information.
   Steering Vibration and Heater ECU*2		Vibrates the steering wheel assembly when there is an overtaking notification.
   Central Gateway ECU (Network Gateway ECU)		Relays the signal between the CAN communication buses.
   DLC3		The Global TechStream (GTS) can be connected to read the Diagnostic Trouble Codes (DTCs) of malfunctions.

   *1: Models with Lexus Safety System +

   *2: Models with Lexus Safety System +A

   *3: The threshold can be adjusted to 1 of 3 levels through the customization function.

   *4: Models with headup display

   *5: Models with navigation system

FUNCTION

1. The RSA system recognizes the following traffic signals using the camera sensor.

   Category		Sign Type	Example of Recognizable Sign
   Speed Limit		Round maximum speed limit/End of speed limit
   No Overtaking		No overtaking/End of no overtaking
   Supplemental Signs	Road condition signs	Ramp Way
   		Rain
   		Wet
   		Ice
   End of Prohibition
   Information signs related speed limit*1	Highway sign (entrance, exit)
   	Motorway sign (entrance, exit)
   	Built-up area sign (start, end)
   	Home zone sign (start, end)
   No Entry*2
   Stop*1

   *1: Models with Lexus Safety System +A

   *2: Models with navigation system

2. The RSA system displays the following traffic signals using the camera sensor.

   Category		Display Example	Details
   Speed Limit Related			Informs the driver of the maximum speed limit of the currently driven road. The displayed sign reflects the speed limit on the recognized sign.
   Speed Limit Related*1			Informs the driver highway sign (entrance, exit).
   			Informs the driver motorway sign (entrance, exit).
   			Informs the driver built-up area sign (start, end).
   			Informs the driver home zone sign (start, end).
   No Overtaking Related			Informs the driver when they are in a no overtaking zone on the currently driven road.
   No Entry*2			Informs the driver that there are vehicle entry restricted sections on the currently driven road.
   All Canceled (All restrictions canceled. Return to default road regulations.)			Informs the driver when all applicable prohibitions, such as speed limit and no overtaking, have ended.
   Stop*1			Informs the driver that there is a stop ahead.
   Speed Limit with Supplemental Sign Related	Ramp Way		Informs the driver of the ramp way direction. However, this item is not displayed when making a lane change without operating the turn signal light.
   	Rain		Informs the driver of the maximum speed limit on the currently driven road when it is raining or the road surface is wet.
   	Ice		Informs the driver of the maximum speed limit on the currently driven road when there is accumulated snow or ice.
   	Blank		The display is blank when the system is unable to recognize a supplemental sign.

   *1: Models with Lexus Safety System +A

   *2: Models with navigation system

   Tech Tips

   A non-official (sign not meeting Vienna Convention) or a recently introduced traffic sign may not be recognized.

3. Notification functions are used in the RSA system which invert the colors of displayed signs, flash signs, etc. to notify the driver.

   
   

   1. Speed Limit Exceeded Notification

      
      

      • While a speed limit sign is displayed, if the actual vehicle speed exceeds the speed limit plus a designated threshold*1, the colors of the displayed sign are inverted and the meter buzzer sounds.*2 For example, if the threshold is set to 5 km/h and the speed limit sign is 60 km/h, the colors of the displayed sign are inverted when the actual vehicle speed exceeds 65 km/h. Furthermore, the system also inverts a speed limit sign with supplemental sign in the same way. However, the system does not invert the colors of the supplemental sign.

        Tech Tips

        *1: The threshold can be adjusted to 1 of 3 levels through the customization function.

        *2: Customization is required for inverted display and sounding of the meter buzzer.

      Notification Method	Display Example
      Inverted Display

   2. No Overtaking Notification

      
      

      • While a no overtaking sign is displayed, if the system detects that the vehicle is attempting to overtake another vehicle, the system flashes the displayed sign and vibrates the steering wheel assembly*1 or sounds the meter buzzer*2.*3

        Tech Tips

        *1: Models with Lexus Safety System +A

        *2: Models with Lexus Safety System +

        *3: Customization is required for blinking display and steering wheel vibration or sounding of the meter buzzer.

      Notification Method	Display Example
      Flashing Display

   3. No-entry Notification (Models with Navigation System)

      
      

      • While a no entry sign is recognized, if the system detects that the driver is driving on a road where entry is prohibited, based on map information, the system flashes the displayed sign and sounds the meter buzzer.*

        Tech Tips

        *: Customization is required for blinking display and sounding of the meter buzzer.

      Notification Method	Display Example
      Flashing Display

4. The RSA system can be turned on or off through the settings tab of the multi-information display.

5. A customization function is used for the RSA, which allows settings such as the notification method and level for exceeding the speed limit to be changed. Setting changes are made through the customization tab of the multi-information display. Refer to the Repair Manual for details.

SYSTEM CONTROL

DIAGNOSIS

1. In order to make system inspections easier to perform, a diagnosis function is used in consideration of serviceability. The DTCs of malfunctioning parts can be read by connecting the Global TechStream (GTS). Refer to the Repair Manual for details.