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TRANSCRIPT
National Highway Traffic Safety Administration
DEVELOPMENT OF A BASIC SAFETY MESSAGE FOR HEAVY TRUCK TRACTOR-TRAILERS
Alrik L. Svenson Office of Vehicle Crash Avoidance and Electronic Controls
Research NHTSA
SAE Government Industry Meeting January 21, 2016
Washington , D.C.
Safer Drivers. Safer Cars. Safer Roads.
• Demonstrated V2V on Heavy Vehicles in Controlled and Naturalistic Environments – Developed prototype V2V trucks and retrofit systems – Driver feedback from Commercial Vehicle Driver Clinics. – Safety Pilot Model Deployment – Performance requirements for safety applications and radio and
communications performance (antenna placement, safety applications)
• Heavy Vehicle Specific Data Analysis and Safety Benefits
– Applicable heavy vehicle V2V crash scenarios and target population.
– Determined V2V safety application effectiveness on tractor trailers and calculated preliminary safety benefits.
• Evaluated unique heavy vehicle issues – Developed Basic Safety Message (BSM) for articulated vehicles
including combination vehicles with 1 or more trailers.
Heavy Vehicle V2V Research Overview
Safer Drivers. Safer Cars. Safer Roads.
• Study was conducted for NHTSA under a Cooperative Agreement with Crash Avoidance Metrics Partnership (CAMP) / Mercedes-Benz Research & Development North America, Inc. (MBRDNA)
• Initiated in June 2013 and completed in May 2015 • Principle Investigators:
– Gordon Peredo – Luca Delgrossi
Acknowledgements
Safer Drivers. Safer Cars. Safer Roads.
• In the Safety Pilot Model Deployment, Tractor-trailers were equipped with V2X hardware and safety applications
• SAE J2735 Basic Safety Messages (BSM) were used
– The BSM only represents vehicles as single, rigid bodies
• An articulated tractor-trailer may not follow rigid body model in all driving situations
– Vehicle can be misrepresented in V2X communications
– May falsely trigger or suppress safety warnings
Background
Safer Drivers. Safer Cars. Safer Roads.
• Develop and demonstrate a method to accurately represent articulated vehicles in V2X communications to:
Project Objective
o Reduce the potential for false warnings
o Reduce the potential for missed warnings (false negatives)
Safer Drivers. Safer Cars. Safer Roads.
• Rigid body model can misrepresent vehicle articulation Actual vehicle position Rigid body model representation BSM
J2735 Vehicle Representation
Perceived Distance
Actual Distance
Safer Drivers. Safer Cars. Safer Roads.
• Baseline simple rigid body model
• Measure tractor and trailer position
• Offset rigid body model
• Calculate trailer tractrix
Possible Options
Safer Drivers. Safer Cars. Safer Roads.
• No additional computations are required onboard the RV • No changes to Target Classification or the Applications are
required onboard the HV
Baseline: Light Vehicle BSM Approach
width
length
vehicle center
vehicle heading
Safer Drivers. Safer Cars. Safer Roads.
• BSM Part I is changed to only reference the tractor • Hitch angle and β (side slip) angle and sufficient set of other
sensors, such as multi-GPS receivers are used to calculate trailer heading and center location. Trailer information is reported in BSM Part II.
• Part II trailer information includes position, size, and path history • Both BSM Parts I and II are sent by the tractor-trailer
Option 1: Actual Tractor and Trailer Locations as Independent Bodies inside one BSM
tractor center
tractor heading
trailer center
hitch angle
Safer Drivers. Safer Cars. Safer Roads.
Option 2: Translate the Rigid Body Model to a Best Fit Inside the Path of the Tractor Trailer
vehicle center
tractor heading hitch
angle
• Keep the length and width of the rigid body model the same, and match the heading of the rigid body model with the tractor heading
• Translate the rigid body model in the longitudinal and lateral directions, so that the rectangle is centered in a weighted average of the articulated tractor-trailer’s planar area
• This solution requires knowledge of the hitch angle in real-time
Safer Drivers. Safer Cars. Safer Roads.
• BSM Part I only references the tractor • Trailer information is contained in BSM Part II, including path
history • The tractor yaw rate is translated into a lateral velocity at the hitch
point which is then translated into a trailer yaw rate. The trailer yaw angle is then integrated and the trailer heading and center are then calculated from the available geometry.
Option 3: Calculate the Tractrix of the Trailer’s Curve in Real-Time
trailer center tractor heading
tractor center
tractor and trailer hitch point
Safer Drivers. Safer Cars. Safer Roads.
• Co-simulation environment created to evaluate vehicle dynamics, body models, target offsets, and safety application results
Simulations
Source: Google Earth. Used with permission
Safer Drivers. Safer Cars. Safer Roads.
Option 3 Selected
• Baseline: Rigid body model
• 1: Measure pose
• 2: Offset rigid body
• 3: Calculate tractrix
Magnifies tractor yaw
Requires sensors
Needs sensor, poor offtracking
Algorithm solution, no sensors (beyond what is already on the tractor)
Safer Drivers. Safer Cars. Safer Roads.
• Modified software in V2X system from Connected Commercial Vehicle Project – Determines tractor and trailer positions and dynamics – Tracks tractor and trailer as separate targets – Packages information in enhanced BSM – Correctly processes BSM in safety application
• Successfully implemented and tested in tractor-trailer • Light vehicle applications successfully modified to process
more complex BSM
Prototype Development
Safer Drivers. Safer Cars. Safer Roads.
• Add optional TrailerInfo to BSM Part II to include: – TrailerCount, TrailerDetailOne, TrailerDetailTwo
(OPTIONAL), and TrailerDetailThree (OPTIONAL) • TrailerCount should be one of the following values:
– 1; 2; or 3 • TrailerDetailOne should be a sequence of the following
BSM components: – PositionLocal3D; Motion; Control; VehicleBasic;
PathHistory (OPTIONAL); PathPrediction (OPTIONAL); and VehicleData (OPTIONAL)
J2735 Standard Recommendations
Safer Drivers. Safer Cars. Safer Roads.
• Tractor-trailer articulation can lead to incorrect warning behavior in V2X safety applications
• Methods were developed to determine accurate tractor-trailer position information
• Prototyped and tested algorithm method – Successful transmission and interpretation of trailer
position via modified BSM Part II • Developed recommendations for modifying SAE J2735 to
accommodate tractor-trailer articulation – Presented to SAE committee in April 2015 – Presented at 2015 ESV Conference in Gothenburg, Sweden
Summary
