Rear Parking Assist System

Specifications

Specification

Item		Specification
Ultrasonic Sensor	Voltage Level	12 V DC
	Detection Range	11.8–39.3 in. (30–100 cm)
	Operating Voltage	9–16 V DC
	Operating Current	60 mA Max.
	Operating Temperature	-40 - 185°F (-40 - 85°C)
	Operating Frequency	52 ± 2 kHz
	Number of Sensors	3 pcs

Components and Component Location

Component Location

1. Body Control Module (BCM)

2. Ultrasonic Sensor

Description and Operation

System Overview

RPAS (Rear Parking Assist System) is an electronic driving assist system that warns the driver to exercise caution when parking or driving at low speed. The sensor uses ultrasonic waves to detect objects in the immediate vicinity of the vehicle. RPAS consists of four RPAS sensors that detect obstacles and transmit the result, divided into three warning levels (first, second and third), to the BCM via the communication line. The BCM determines the alarm level from the communication message transmitted by the slave sensors, and then activates the buzzer or transmits data for 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. The BCM sends a request message once to each sensor to check the initial system status, and the four sensors respond simultaneously. At this time, if there is no problem, the alarm starts after 500 ms. R gear shift interval is 300 ms.
   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 objects (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, RC, RR each sensor operation).

Indirect measurement

(RC → RL, RC → RR in sequence) With two or three sensors, one sensor transmits and 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 Alarm System. When an RPAS sensor detects an object, a warning is given by 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 with priority. It acts as a gateway only when sending visible warning devices such as the cluster.

• Sensor Information Processing Method for Buzzer/Display BCM. For RL/RR sensor information, the BCM processes the information of each sensor directly for the display and buzzer function. For the CL/CR sensor buzzer output, the BCM processes the center combination information by the priority of both sensors.

System Operation Specification. When the system is powered (after IGN ON and shifting to R), the MICOM checks each sensor channel. If any error is detected, it sounds the buzzer 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 start alarm. The normal mode entry operation is as follows.

With R gear engaged, the system operates as follows.

With R gear disengaged, the system operates as follows.

※ The allowable error range on the oscilloscope waveform is ±10%. Alarm output characteristics are classified by the distance between sensors. The state logic according to alarm level priority is as follows. (Same sensor)

* Determination of α value

1. 1
   Low priority sensor off: α = 0 ms
2. 2
   Low priority sensor - 1st level warning: α < 340 ms
3. 3
   Low priority sensor - 2nd level warning: α < 170 ms
4. 4
   Low priority sensor - 1st level warning: β = 1700 ms
5. 5
   Low priority sensor - 2nd level warning: β = 1700 ms
6. 6
   Low priority sensor - 3rd level warning: β = 700 ms
7. 7
   First Warning Zone (31.9 in. (81 cm) - 47.2 in. (120 cm))

   

8. 8
   Second Warning Zone (16.1 in. (41 cm) - 31.5 in. (80 cm))

   

9. 9
   Third Warning Zone (less than 15.7 in. (40 cm))

   

   

*Determination of β value. Alarm control by detection distance is as follows. Visual Alarm Indicator Specification. When the transmission is shifted 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 detection operation, the indicator stays on for 2 seconds before turning off. (However, when the third-stage alarm changes to "No Alarm" state, 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 diagnosis result to the BCM according to this specification. The BCM performs the alarm output function. The display shows the transmitted position and alarm data. In alarm mode, the system finds the nearest sensor and gives the alarm for the nearest sensor first. (For example, if RL is the first warning stage and RR is the third warning stage, the RR alarm takes priority.)