Collision Avoidance Module: 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.
PAS consists of Six(Front:2, Rear:4) PAS 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 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) R-PAS Starting buzzer" is normally worked, when sensor does not send an error message and after finishing error diagnosis.
(5) If any failure is received from the 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 display is shown continuously until it is repaired completely.
2. NORMAL Mode
(1) LIN communication starts and keeps the routine after IGN1 ON+R gear
(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.
(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 (Front sensor have second and third alarms.)
(5) The efficient vehicle speed of RPAS operation is under 10Km/h.
(6) Refer to 'Digital PAS Project LIN communication' for the more detailed communication specification.

Sensing Area
1. Measurement condition - PVC pole (diameter 75mm, length 3m), normal temperature
2. Distance range detected objects (Measured directly in front of sensor)






Horizontal Sensing Area





Vertical Sensing Area





Distance Measurement
Direct Measurement
Transmission and Reception are executed with one sensor
(RL, RCL, RCR, RR each sensor execution)




Indirect Measurement
(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 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.