Kia Optima: Description and Operation

System Overview

RPAS(Rear Parking Assist System) is an electronic driving aid device warning driver to be cautious when they park or speed low after detecting an object on side and behind of vehicle by using the feature of ultrasonic waves.

RPAS consists of four RPS sensors which are detecting the obstacles and transmit the result separated into three warning levels, the first, second and third to BCM by Lin communication.BCM decides the alarm level by the transmitted communication message from the slave sensors, then operate the buzzer or transmits the data for display.

System Block Diagram

System Operation

Initial Mode

1.	RPAS checks the ID and Reference (shaping table) during the initialization using LIN communication.

2.	If sensor ID or sensor parameter is same with expected value, RPAS system is initialized within 500ms after turning IGN1 and shifting R gear.

3.	If Sensor ID or sensor parameter is different with expected value, initial mode can take about 1.2 second after turning IGN1 and shifting R gear because of teaching sensor ID or sensor parameter.

4.	RPAS executes the diagnosis of each sensor during the initialization. T1 : RPAS initializing time (1) In case of sensor teaching, T1 : within 1.2 second (2) In case of normal condition, T1 : 500ms ± 10%

Normal Mode

Normal mode of RPAS can divide as two steps.

First step is a mode to inform the driver of the RPAS system ON and diagnosis results which is executed during the initialization.

Second step is the obstacle detection mode to give driver warning when detecting the obstacle.

1.

Driver info mode for RPAS ON (1) If there aren’t any diagnosis messages from sensors, the normal RPAS ON sound with ON-period 300ms warn after initializing time since R gear is shifted. The obstacle detection warning starts after the delay of 100ms since finishing the normal RPAS ON warning sound. (2) If there are any failure sensor, “Warning of sensor fail” sound is driven during the fixed period and if there is any display unit, it displays the diagnosis. Refer to the Diagnosis buzzer sound for more detail Information. T1 : RPAS initializing time (1) In case of sensor teaching, T1 : within 1.2 second (2) In case of normal condition, T1 : 500ms ± 10% T2 : Refer to the spec for warning of fail (3) “Diagnosis-buzzer” is driven only one time but the display unit continue to display the diagnosis according each failure sensor’s location.

2.

Obstacle detection mode (1) There are 3 kinds of warning sound for detecting the obstacle, the 1st warning and the 2nd warning are the intermittent sound and the 3rd warning is the continuous sound. (2) The vehicle speed for the operation of RPAS is below 10Km/h . (3) There are 2 kinds of detection mode. One is for normal operating mode using normal 4 sensors. Even if any sensor is on failure condition, the RPAS system will be entered to degrade mode excepting a failure sensor. (4) Operating procedure

Detection Area

1.	Test condition – PVC pole(Diameter 75mm, Length 1m) & At the room temperature

2.	Distance tolerance (measured at the front of sensor) 81 cm ~ 120 cm : ± 15 cm 41 cm ~ 80 cm : ± 10 cm Below 40 cm : ± 10 cm

3.	Below 30 cm may not be detected.

4.

Sensing zone specification Sound pulse has a fixed duration. Pause between pulses is related to the distance from the obstacle and is not variable. Although the position of the obstacle is not moving during sometime, the buzzer should keep warning. And although an obstacle that is currently warned is getting far, the buzzer should keep warning according to obstacle distance. The warning sound is generated by the algorithm of ECU which measures the distance of the obstacle from the sensor. The distance is divided into three detection ranges. Obstacles below 30cm from the sensor may not be detected.

Each Warning Zone Hysteresis Function for buzzer and display.

Condition	1st Warning (120cm)	2nd Warning (80cm)	3rd Warning (40cm)
the distance between vehicle and obstacle is getting close	Immediately warning
the distance between vehicle and obstacle is getting far	2sec warning delay	2sec warning delay	1sec warning delay

Warning method of RPAS

If RPAS sensor detects the obstacle, the acoustic device makes warning sound and the display module (Cluster) indicates each warning level as like followings.

RPAS sensor sends the distance data to BCM through LIN communication and BCM received the distance data from each sensor.

BCM has the responsibility of the acoustic function.

BCM has the responsibility of the gateway function that BCM sends the warning data to Cluster as like below timing diagram.

When change from a warning area to the different zone, after finishing one cycle of warning output, the next warning sound has to start for different zone necessarily.

Timing Chart for RPAS Warning Sound

If Power is supplied to the system (turning IGN1 and shifting R gear), BCM checks the channel of each sensor and if no problems, the buzzer sound with turn-on period 300ms is generated after 500ms, but even if one sensor has a problem, the buzzer sound not for “Start-buzzer of RPAS” but for “Diagnosis-buzzer of RPAS”, The next action for Normal mode is like followings.

After R gear is armed, the system operation is like followings.

Time tolerance: ±10%

After R gear is disarmed, the system operation is like followings.

Time tolerance: ±10%

Sensor interval distance dividing alarm output specification

The condition logic is as below according to phase logic in priority. (In same sensor)

RPAS operation ranges according to distance are as below.

1.	First alarm (81 cm ~ 120 cm)

2.	Secondary alarm (41 cm ~ 80 cm)

3.	Third alarm (40 cm or less)

4.

Failure alarm cycle When the system starts and sensor has errors, the warning sound as the sensor position is like following. ※ In the case that the multiple sensors have errors, the sequence of sensor’s warning is like followings. RL → RCL → RCR → RR ※ After the warning sound for diagnosis is generated, the other normal sensors execute the normal function such as the detection and the transmission of distance data. 1. Time tolerance of the above waveform : Time ± 10% 2. At nearer distance than 30cm, detection may not occur. 3. Alarm will be generated with vehicle reversing speed 10km/h or less. 4. For moving target, maximum operation speed shall be target approach speed of 10km/h. 5. When the vehicle or the target is moving, sequential alarm generation or effective alarm may be failed. 6. False alarm, or failure of the alarm to trigger may occur in the following conditions. - Irregular road surface, gravel road, reversing toward grass. - Horn, motor cycle engine noise, large vehicle air brake, or other object generating ultrasonic wave is near. - When a wireless transmitter is used near to the sensor. - Dirt on the sensor. - Sequential alarm may not occur due to the reversing speed or the target shape.

Method of error handling

■ LIN BUS Off error

Division	Condition for error	Condition for the disarmed
Initial routine	Detecting LIN BUS OFF one time	Disarmed (if LIN BUS ON is detected 4 consecutive times in general routine)
Normal routine	Detecting LIN BUS OFF 4 consecutive times	Disarmed (if LIN BUS ON is detected 4 consecutive times)

※ Remarks

1.	LIN BUS OFF means no response from sensors when BCM send request to sensors.

2.	In the case that error happens to the initial routine, diagnosis warning sound + display for error

3.	In the case that error happens to the Normal routine, the only display for error

4.	If error happens to the direct condition of each sensor, after that, error is transmitted at the indirect condition (sensor side).

■ In the case of sensor error

Division	Condition for error	Condition for the disarmed
Initial routine	Detecting the message of sensor error	Disarmed(if the message which sensor is normal is detected 4 consecutive times , but it is impossible to be disarmed in the initial routine)
General routine	Detecting the message of sensor error 4 consecutive times	Disarmed(if the message which sensor is normal is detected 4 consecutive times)

※ Remarks

1.	In the case of fault counting output message or signal with last valid should be transmitted.

2.	In the case that error happens to the initial routine, diagnosis warning sound + display for error

3.	In the case that error happens to the general routine, the only display for error