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SAE J2735-Draft-Rev18 [issued: 06-26-07]
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189 -
This is an SAE Motor Vehicle Council draft document of the DSRC committee, subject to change.
Annex A-5 Left Turn Assistant
Application Description
The Left Turn Assistant provides information to drivers about gaps and speeds of oncoming cars to help
them make a left turn across traffic. This application warns drivers when a collision is probable if the left
turn movement is initiated.
Flow of Events
Flow of events
1.
Oncoming Vehicle “A” sends MSG_BasicSafetyMessageFrame, Part I.
2.
Turning Vehicle “B” receives message
3.
Vehicle “B” recognizes that Vehicle A’s message is relevant (crossing road
segment via map and/or heading and indication of turn)
4.
Vehicle “B” alerts its driver to an oncoming vehicle hazard.
Hardware Devices:
DSRC radio
Positional Sensors
Human-Machine Interface
Occupant
Vehicle
System
Driver
Passenger
Service
Provider
Road
Department
Actors: (What entities
play an active role in
use)
X
X
Support information:
CAMP-VSC Task 3 Report, 2003
Concept of Operations
DSRC communications is used to allow the turning vehicle to detect all equipped vehicles in the vicinity.
Furthermore, it allows the turning vehicle to receive the position, velocity, acceleration, and control
parameters, among others, for potential threat vehicles. The in-vehicle unit, based upon the host vehicle’s
left turn signal initiation (and/or possibly other control parameters such as steering wheel angle or yaw rate)
constructs a potential vector for the host vehicle and analyzes the received parameters for the approaching
vehicles as contained in their MSG_BasicSafetyMessageFrame, Part I and
MSG_BasicSafetyMessageFrame, Part II messages. The unit also constructs expected future vectors for
these vehicles. If this analysis determines that a collision would be likely if the left turn movement is
initiated, an appropriate warning is issued to the driver
Sensors and Other System Needs
On-board sensors to determine the host vehicle’s intent to turn left, e.g., left turn signal or other control
parameters, may be required.