System Overview
RPAS(Rear Parking Assist System) is an electronic driving aid device warning
driver to be cautious during parking or low speed when after detecting an object
on side and behind of vehicle by using the feature of ultrasonic waves.
RPAS consists of four RPS sensors which detect the obstacles and transmit
the result in three separate 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 Specification.
1. |
INIT mode
(1) |
System initializing time is 500ms after IGN1+ R Gear.
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(2) |
RPAS recognizes ID and sets the sensor ID up during initialization.
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(3) |
RPAS activates each sensor and then executes the diagnosis
after finishing initialization of BCM
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(4) |
RPAS Starting buzzer” is normally worked, when sensor
does not send an error message and after finishing error diagnosis.
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(5) |
If any failure is received from the any sensors, RPAS
Starting Buzzer” does not work but the failure alarm is operated
for a moment.
If you have display option, warning sign is also shown
on it.
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(6) |
Buzzer for sensor failure is operated once, but display
is shown continuously until it is repaired completely.
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2. |
NORMAL Mode
(1) |
LIN communication starts and keeps the routine after IGN1
ON+R gear
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(2) |
BCM send a message once to each sensor for operating request
to check the initial status of the system and four sensors response
at a time. At this time, if there is no problem, the alarm starts
after 500ms of R gear shifting at 300ms intervals.
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(3) |
After initialization, normal mode starts 100ms later after
finishing alarm output.
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(4) |
Alarm for obstacles is divided into 3 levels.
The first and second are intermittent sound, and the third
alarms continuously
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(5) |
The efficient vehicle speed of RPAS operation is under
10Km/h.
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(6) |
Refer to ‘Digital PAS Project LIN communication’ for the
more detailed communication specification.
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Sensing Area
1. |
Measurement condition – PVC pole (diameter 75mm, length 3m), normal
temperature
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2. |
Distance range detected objects (Measured directly in front of
sensor)
81cm(31.9in) ~ 120cm(47.2in) : ± 15cm(5.9in)
41cm(16.1in) ~ 80cm(31.5in): ± 15cm(5.9in)
Less than 40cm(15.7in) : ± 10cm(3.9in)
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Horizontal Sensing Area
Vertical Sensing Area
Distance Measurement
Transmission and Reception are executed with one sensor
(RL, RCL, RCR, RR each sensor execution)
(RCL → RL, RCL → RCR, RCR → RCL, RCR → RR Execution in order)
With two or three sensors, one of them sends the transmission and the
others get the reception.
Direct and Indirect Measurement at
once |
With two or three sensors, the one sensor performs both transmission and
reception, and the others perform only reception.
RPAS alarm system
When the RPAS sensor detects the object, warning is operated by audible
alarm device as like buzzer. RPAS sensor sends data to BCM with LIN communication
and BCM implements audible warning for each RPAS SENSOR by priority. And it
performs a role of gateway only when it sends visible alarm device such as Cluster.
- |
Sensor buzzer/display information processing method of BCM In
case of RL/RR sensor information, the BCM handles each sensor information
directly about Display and buzzer output function. Buzzer output of
CL/CR sensor, BCM handles center combination information by priority
both sensor.
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System Operation Spec
When the system has the power (after IGN ON and R gear), MICOM checks
every sensor channel. In case it is not find any error, it sounds 300ms buzzer
500ms afterward. But it finds any error even a sensor, it sounds buzzer corresponding
fault sensor instead of initial starting alarm. Function for normal mode entrance
is as below
With R Gear, system function is as below
With R gear releasing, system function is as below
※acceptable error range on waveform ±10%
Alarm Output Specification classified by distance between sensors
Condition logic according to priority of alarm level is as below. (the
identical sensor)
*α value definition
1. |
low priority sensor off : α = 0ms
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2. |
low priority sensor is 1st warning level : α < 340ms
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3. |
low priority sensor is 2nd warning level : α < 170ms
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*β value definition
1. |
low priority sensor is 1st warning level : β = 1700ms
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2. |
low priority sensor is 2nd warning level : β = 1700ms
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3. |
low priority sensor is 3rd warning level : β = 700ms
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Alarm control by sensing distance is as below
1. |
First warning area (81cm ~ 120cm)
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2. |
Second warning area (41cm ~ 80cm)
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3. |
Third warning area (less than 40cm)
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4. |
Period of fault alarm
(1) |
With visible display
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(2) |
Without visible display
When the system has error channel in initial time, sensor
channel notify the location of error via hearing device. (Three
times for each sensor)
1. |
Time tolerance of the above waveform :
Time ± 10%
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2. |
At nearer distance than 30cm, detection
may not occur.
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3. |
Alarm will be generated with vehicle reversing
speed of 10km/h or less.
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4. |
For moving target, maximum operation speed
shall be target approach speed of 10km/h.
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5. |
When the vehicle or the target is moving,
sequential alarm generation or effective alarm
may be failed.
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6. |
False alarm, or failure of the alarm to
trigger may occur in the following conditions.
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- |
Irregular road surface, gravel road, reversing
toward grass.
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- |
Horn, motor cycle engine noise, large
vehicle air brake, or other object generating
ultrasonic wave is near.
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- |
When a wireless transmitter is used near
to the sensor.
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- |
Sequential alarm may not occur due to
the reversing speed or the target shape.
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Error Handling
Section
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Error recognition condition
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Error releasing condition
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Initial Routine
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LIN BUS OFF sensing once
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Error is not released in initial mode.
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Normal Routine
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LIN BUS OFF is sensed times in a row
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The fault is released when BCM or LIN Master senses LIN BUS ON four
times in a row in normal mode
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※ Remark :
1. |
In fault counting, output message or signal should be transmitted
as a Last Valid value.
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2. |
Error in initial mode, fault buzzer (BCM) is operated.
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Sensor fault (LIN Msg : 0x08) |
Section
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Error recognition condition
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Error releasing condition
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Initial Routine
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Sensor fault Message sensing once
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Error is not released in initial mode.
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Normal Routine
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Sensor fault Message sensing four times in a row
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The fault is released when BCM or LIN Master senses LIN BUS ON four
times in a row in normal mode
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※ Remark :
1. |
In fault counting, output message or signal should be transmitted
as a Last Valid value.
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2. |
Error in initial mode, fault buzzer (BCM) is operated.
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3. |
When the error occurs in direct condition, the sensors sent the
same status of error for indirect condition
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Communication Standard
This section defines the communication between RPAS and BCM.
RPAS send a detecting result of object and sensor diagnosis result to
BCM according to this document, and BCM takes a role to alarm.
Indicator shows the transmitted position and alarm data, in alarm case,
it finds the nearest DATA and alarms the nearest DATA first.
(Ex. In case, RL is first step alarm and RR is third step, RR alarm has
priority.)
Component Location
1. IPM
2. Ultrasonic sensor
3. Rear parking assist switch (OFF)
※ The IPM contains the rear parking assist system ...