Description and Operation

System Overview

RPAS (Rear Parking Assist System) is an electronic driver assistance system that warns the driver to use caution when parking or driving at low speed. The sensors use ultrasonic waves to detect objects within close proximity of the vehicle. RPAS consists of four RPS sensors that detect obstacles and transmit the result, divided into three warning levels (first, second, and third), to the BCM over the communication line. The BCM determines the warning level from the communication message transmitted by the slave sensors, and then activates the buzzer or transmits data to the display.

System Operation Specification

1. 1
   INITIAL Mode

   1. The system initialization time is 500 ms after IGN1 + R gear.
   2. RPAS recognizes the LID and sets the sensor identifier during initialization.
   3. RPAS activates each sensor and then performs diagnosis after BCM initialization is completed.
   4. If diagnosis is completed and the sensor does not send an error message, the "RPAS starting buzzer" normally operates.
   5. If a failure is received from any sensor, the R-PAS starting buzzer does not operate, but the warning tone sounds momentarily. If the vehicle is equipped with a display option, a warning symbol is also shown on the display.
   6. The buzzer sounds once for a sensor failure, but the sensor failure status is displayed on the display until the malfunction is repaired.
2. 2
   Normal Mode

   1. LIN communication starts and continues the procedure after IGN1 ON+R.
   2. BCM sends a message once to each sensor as an operation request to check the initial state of the system, and all four sensors respond once. At this time, if there are no problems, the alarm starts 500 ms after shifting into R, with a 300 ms interval.
   3. After initialization, normal mode starts 100 ms after the alarm output is completed.
   4. The obstacle warning is divided into 3 levels. The first and second levels sound intermittently, and the third level sounds continuously.
   5. The effective vehicle speed for RPAS operation is less than 10 km/h.
   6. Refer to "Digital PAS LIN Communication" for more detailed communication specifications.
3. 3
   Measurement conditions: PVC pole (diameter 75 mm, length 1 m), normal temperature.
4. 4
   Distance to detected object (measured directly in front of the sensor): 61 cm (24.0 in.) ~ 120 cm (47.2 in.): ± 15 cm (5.9 in.); 31 cm (12.2 in.) ~ 60 cm (23.6 in.): ± 15 cm (5.9 in.); less than 30 cm (11.8 in.): ± 10 cm (3.9 in.)

   

   

Detection Zone / Horizontal Detection Zone / Vertical Detection Zone / Distance Measurement

Direct measurement

Transmission and reception are performed by one sensor (RL, RCL, RCR, RR for each sensor configuration).

Indirect measurement

(RCL > RL, RCL > RCR, RCR > RCL, RCR > RR, performed in order) With two or three sensors, one sensor transmits while the others receive.

Direct and indirect measurement at the same time

With two or three sensors, one sensor performs both transmission and reception, and the others perform reception only.

RPAS Warning System: When an RPAS sensor detects an object, a warning is issued through an audible warning device such as a buzzer. The RPAS sensor sends data to the BCM via LIN communication, and the BCM outputs the audible warning for each RPAS sensor according to priority. It also acts as a gateway only when sending to a visual warning device such as the cluster.

• Buzzer and display processing method of BCM. In case of RL/RR sensor information, BCM processes each sensor information directly for the display and buzzer output function. For CL/CR sensor output, BCM processes the information as a center combination, with priority given to both sensors.

System Operation Specification: When power is supplied to the system (after IGN ON and R gear shift), the MICOM checks each sensor channel. If an error is detected, the buzzer turns off for 300 ms after 500 ms. If an error is detected in a sensor, it sounds the buzzer corresponding to the faulty sensor instead of the initial startup signal. The operation to enter normal mode is as follows.

With R gear engaged, the system operates as follows.

With R gear disengaged, the system operates as follows.

* The permissible error range on the oscilloscope waveform is ±10%. Alarm output characteristics classified by distance from the sensor. Status logic according to alarm level priority is as follows. (Same sensor)

* Value determination

1. 1
   Low-priority sensor off: ? = 0 ms
2. 2
   Low-priority sensor - 1st warning level: ? < 340 ms
3. 3
   Low-priority sensor - 2nd warning level: ? < 170 ms
4. 4
   Low-priority sensor - 1st warning level: ? = 1700 ms
5. 5
   Low-priority sensor - 2nd warning level: ? = 1700 ms
6. 6
   Low-priority sensor - 3rd warning level: ? = 700 ms
7. 7
   First warning zone (61 cm~120 cm)

   

8. 8
   Second warning zone (31 cm~80 cm)

   

9. 9
   Third warning zone (less than 30 cm)

   

   

* Value determination. Distance-based alarm control operates as follows. Visual Alarm Indicator Specification: When the shift lever is moved to R, the cluster controls the indicator as shown in the following figure. When the system detects an object, the indicator turns on immediately. If the object disappears during RPAS operation, the indicator remains on for 2 seconds before turning off. (However, when the third-step alarm changes to No Alarm, it lights for two seconds and then turns off.)

• It only indicates the obstacle detection position.
• At the third warning level, the indicator flashes at one-second intervals.
• In normal warning mode, the built-in display RCR/RCL

Communication Standard: This section defines the communication between the RPAS and the BCM. The RPAS sends the object detection result and the sensor diagnostic result to the BCM in accordance with this document, and the BCM takes on the role of issuing the alarm. The indicator shows the transmitted position and alarm data; in alarm mode, it finds the nearest DATA and gives the alarm to the nearest DATA first. (For example, if RL is the first-step alarm and RR is the third-step alarm, the RR alarm has priority.)