RPAS (Rear Parking Assist System) is an electronic driving
aid that warns the driver to be cautious while parking or driving at low
speed. The sensor uses ultrasonic waves to detect objects within
proximity of the vehicle.
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, and then operates 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. |
(2) |
RPAS recognizes LID and sets the sensor ID up during initialization. |
(3) |
RPAS activates each sensor and then executes the diagnosis after finishing initialization of BCM |
(4) |
If the diagnosis is completed and sensor does not send an error message, “RPAS Startling Buzzer” is normally worked. |
(5) |
If failure is received from any sensors, R-PAS 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. |
(6) |
Buzzer for sensor failure is operated once, but the sensor failure state is shown in display until the failure is repaired. |
|
2. |
NORMAL Mode
(1) |
Lin communication starts and keeps the routine after IGN1 ON+R gear |
(2) |
BCM sends a message once to each sensor for operating request
to check the initial status of the system and four sensors response all
at once. At this time, if there is no problem, the alarm starts after
500ms of R gear shifting at 300ms intervals. |
(3) |
After initialization, normal mode starts 100ms later after finishing alarm output. |
(4) |
Alarm for obstacles is divided into 3 levels.
The first and second are intermittent sound, and the third alarms continuously |
(5) |
The efficient vehicle speed of RPAS operation is below 10Km/h. |
(6) |
Refer to ‘Digital PAS Project LIN communication’ for the more detailed communication specification. |
|
3. |
TUNNING MODE
(1) |
Start condition of the basic operation in NORMAL MODE is
applied to TUNNING MODE. Use the TUNNING TOOL as MASTER instead of BCM
MASTER. |
(2) |
Therefore, BCM is not connected with LIN BUS |
(3) |
TUNNING TOOL receives the reference and envelop data in a LIN
Diagnostic format and then displays in the analogue method by
communicating with sensors. |
(4) |
Refer to ‘Digital PAS Project_LIN_communication’ for the more detailed communication Specification. |
|
4. |
CONFIGURATION MODE
(1) |
Purpose of CONFIGURATION MODE as follows.
A. |
Check assigned ID for each sensor |
B. |
Check variant ID for each sensor |
|
(2) |
Start condition of the basic operation in NORMAL MODE is
applied to CONFIGURATION MODE. Use the TUNNING TOOL as MASTER instead of
BCM MASTER. |
(3) |
Therefore, BCM is not connected with LIN BUS. |
(4) |
Always check the supplier ID and function ID of each sensor via LIN Bus before entering TUNNING TOOL. |
(5) |
Refer to ‘Digital PAS Project LIN communication’ for the more detailed communication Specification |
|
Sensing Area
1. |
Measurement condition – PVC pole (diameter 75mm, length 1m), normal temperature |
2. |
Distance range detected objects (Measured directly in front of sensor)
61cm(24.0in) ~ 120cm(47.2in) : ± 15cm(5.9in)
31cm(12.2in) ~ 60cm(23.6in): ± 15cm(5.9in)
Less than 30cm(11.8in) : ± 10cm(3.9in) |
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
via 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. |
System Operation Spec
When the system has the power (after IGN ON and R gear),
MICOM checks every sensor channel. In case it finds any error, it gives
off the buzzer for 300ms after 500ms.
If an error is found even in a sensor, it gives off the
buzzer corresponding to the faulty sensor, instead of initial starting
alarm. The operation to enter the normal mode is as follows.
With the R gear put in the car, the system is operated as follows.
With the R gear released, the system is operated as follows.
? The acceptable error range on waveform is ±10%.
Alarm Output Specification classified by distance between sensors
Condition logic according to priority of alarm level is as below. (the identical sensor)
*? value definition
1. |
low priority sensor off : ? = 0ms |
2. |
low priority sensor is 1st warning level : ? < 340ms |
3. |
low priority sensor is 2nd warning level : ? < 170ms |
*? value definition
1. |
low priority sensor is 1st warning level : ? = 1700ms |
2. |
low priority sensor is 2nd warning level : ? = 1700ms |
3. |
low priority sensor is 3rd warning level : ? = 700ms |
Alarm control by sensing distance is as follows.
1. |
First warning area (61cm ~ 120cm) |
2. |
Second warning area (31cm ~ 80cm) |
3. |
Third warning area (less than 30cm) |
Visible Alarm Indicator Specification
When the gear shifts to R, the cluster controls the indicator as the following picture.
When the system detects an object, it immediately turns on
the indicator. If an object disappears while the RPAS detecting
operation, the indicator remains on for 2 sec. before being turned off.
(The third alarm>
- |
It shows only the detecting position of obstacles. |
- |
In third level alarm, indicator flickers at intervals of a second. |
- |
In normal alarm mode, integrated display of RCR/RCL |
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 issue
an alarm.
Indicator shows the transmitted position and alarm data, in
the alarm mode, it finds the nearest DATA and alarms the nearest DATA
first.
(Ex. In case, RL isthe first-step alarm and RR is the third step, RR alarm has priority.)