When reversing, the driver is not easy to find objects in the
blind spots and to determine the distance from the object. In order to
provide the driver safety and convenience, back warning system will
operate upon shifting to "R" Ultrasonic sensor will emit ultrasonic wave
rearward and detect the reflected wave.
Control unit (BCM) will calculate distance to the object
using the sensor signal input and output buzzer alarm in three steps
(first, second and third alarm).
Block Diagram
Operation
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.
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.