Transcript No Slide Title

PATH Research on
Truck Automation Technology
Steven E. Shladover, Sc.D.
ITFVHA Meeting
Troy, MI, July 2004
1
Outline
• Motivations for truck automation research
• Automatic steering for lane keeping accuracy
• Automated vehicle following in platoon for
lane capacity, drag reduction
• Aerodynamic drag reduction results
• Fuel and emissions savings
2
Motivations for PATH Truck Research
• Trucking is vital to California’s shipping
industry (major ports – LA/Long Beach,
Oakland)
• Major ports are in most congested urban
regions, imposing serious delays and
unreliability into goods movement
• Trucks have economic incentives to be early
adopters of ITS technologies (productivity
and safety)
• Dedicated truck lanes under study in Los
Angeles region could facilitate use of new
technologies and operations
3
PATH Experimental Trucks
4
Testing Truck Fully Loaded
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6
Automatic Steering Control
• Accurate lane tracking permitting narrower
dedicated truck lanes
– Fit in former rail rights of way
– Lower land and construction costs
• Enabler for fully automated driving
Results
• Testing on old truck at Crows Landing
• Accurate lane tracking with same controller,
with and without trailer
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Crows Landing Lateral Control Test Site
400 m
R
200 m
200 m
400 m
R
N
400 m
R
R=800 m
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Steering Control with and without Trailer
Note: Lateral
displacements
of 25 cm are only
at curve reversals
on test track
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Automatic Speed and Spacing Control
• Cluster trucks in close-formation platoons to
increase truck lane capacity (doubling of
capacity using 3-truck platoons)
• Close separation has added benefits:
– Drag reduction saves fuel
– Drag reduction reduces emissions as well
• Extensive testing of truck longitudinal control
in 2003
10
Truck Power Limitations
• Maximum engine power can only provide
0.035 g acceleration for loaded truck
• Highway grades can exceed 6%
• Disturbances produce serious losses of
available power:
– Transmission shifts (~1 sec. loss of torque)
– Engine cooling fan (42 Hp)
– Air conditioner (5.2 Hp)
– Air compressor, water pump, generator
(>2 Hp each)
11
Truck Braking Challenges
• Pneumatic foundation brakes
– Slow response (600-800 ms)
– Large, continuously variable torque after initial step
– Applied at each wheel
• Transmission retarder
– Slow response (1000 ms)
– Limited, continuously variable torque, depending on
drive line speed
– Applied through drive line to drive wheels
• Compression (Jake) brake
– Fast response (20 ms)
– Limited, discrete torque steps (2, 4 or 6 cylinders)
– Torque depends on engine speed (>800 rpm)
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Accurate Longitudinal Control
• Truck following speed profile command
– Speed errors less than 0.5 m/s
– Position errors generally less than 1 m
• Robust to loading variations
• Current experimental work:
– Accurate longitudinal control of 2-truck platoon,
–
–
–
–
coordinated via 802.11 wireless
Integrated control of WABCO EBS, compression
brake and transmission retarder
Direct measurements of fuel and emissions
Smooth manual/automatic/manual transitions
Limited fault detection and identification
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Two-Truck Platoon Test Scenarios
• Vehicle following
– 1st Truck: Fully loaded (M=31,795 kg)
– 2nd Truck: Half loaded (M=22,226 kg)
• Speed range tested: 45 ~ 55[mph] – 72 – 88 km/h
• Inter-vehicle distance: 4~10 m
• Flat test track with total length ~ 2250 m
• Combined braking system tested
– Air brake (EBS) + Jake brake + Transmission
retarder
– 2nd truck has modified EBS Box with 0 initial value
– 1st truck has default initial value for deceleration of
0.25 m/s^2
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Truck Platoon Maneuvers
•
•
•
•
1st truck speed to follow a predefined profile
(following a virtual vehicle)
2nd truck to follow the 1st to keep constant
inter-vehicle distance
Maximum accelerations tested
– a = 0.55 m/(s^2) when v = 2 m/s
– a = 0.24 m/(s^2) when v = 14 m/s
– a = 0.06 m/(s^2) when v = 25 m/s
Maximum deceleration range tested
– 0.9 m/(s^2)
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Truck Platoon Test Results
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•
•
Each test run has 3 figures.
Units & terminology used in the following
figures:
– spd: Speed [mph]
– dist: distance
– dist_err: distance error [m]
– spd_err: speed error [m/s]
Colors used in plotting:
- red - 1st truck
- green – 2nd truck
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Run 6: Max speed 55 mph ; Des_dist: 4 m
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Run 6: Max speed 55 mph ; Des_dist: 4 m
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Run 6: Max speed 55 mph ; Des_dist: 4 m
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Aerodynamics of Class-8
Tractor-Trailer Trucks
• Research led by Prof. Fred Browand, USC
• Scale-model tests in wind tunnel, then full-
scale tests on track
• Measuring effects on aerodynamic drag of:
– Separation between trucks (primary
purpose)
– Cross-wind components
– Tractor-trailer spacing
• Strong effects seen on separation between
trucks and on shape of front of truck
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Wind-Tunnel Truck Models
• Note blunt front comparable to cab-over-engine design tractor
22
Drag vs. Truck Separation in Wind Tunnel
Blunt - Blunt
CDAvg = (CDF + CDR)/(CDF iso+ CDR
iso)
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Direct Measurements of Fuel
Savings in Platoon
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Comparison of Wind Tunnel and
Direct Measurements of Fuel Saved
25
Heavy-Duty Diesel Truck Energy and
Emissions
• Research led by Prof. Matthew Barth (UCR)
• Modal Emissions Research Lab (MERL) trailer
developed for EPA, CARB and engine
manufacturers
• Data collection on automated trucks at Crows
Landing, individually and as platoon leader
and follower
– Platoon results compared to baseline case
of individual truck at same speed
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Emissions Results
• Challenging data collection because of variable
test conditions (ambient wind, rough road surface,
manual steering variations, flow distortions at rear
of MERL trailer)
• CO2 reductions (not smooth with spacing)
Spacing
Front Truck Rear Truck
10 m
8.1 %
15.5%
4m
11.3 %
17.7%
• NOx reductions (Rear better and front worse at
intermediate gaps)
Spacing
Front Truck Rear Truck
10 m
5.6 %
1.4 %
4m
4.4 %
1.1%
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Summary
• Truck automation is significantly more
•
•
•
•
difficult than automation of cars
– Power limitations and slow responses
Successful automatic steering and speed
control have been demonstrated under a
limited range of conditions
Very close separations have been achieved
between trucks on test track
Fuel consumption savings are significant, but
emissions effects are less certain
More refinements and testing are needed
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Assessment of the Applicability of
Cooperative Vehicle-Highway Automation
Systems (CVHAS) to Freight Movement in
Dedicated Lanes in Chicago
Steven E. Shladover, Sc.D.
California PATH Program
University of California, Berkeley
ITFVHA Meeting, July 2004
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Project Goals
• Explore truck lane alternatives to relieve
congestion in Chicago
• Identify how automation technologies can
enhance truck lane operations
• Provide real-world example of deployment
opportunities for automation technologies
– Automatic steering control
– Automatic longitudinal control in
platoons
– Fully automated driving
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Automatic Steering Control
• Automatically steer truck, with accurate lane
positioning (6 inch accuracy proven up to 65
mph in PATH tests)
• Enables full-speed operations in narrower
lanes (10 ft rather than standard 12 ft lane)
• Narrower lanes provide ROW flexibility and
save construction costs (especially bridges)
• Reference markers at $5 – 10 K per mile
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Automatic Steering Cost per Truck
Steering Actuator
Near-Term
Long-Term
(Hundreds of (Thousands of
trucks)
trucks)
$2.5 K
$0.5 K
Magnetic Sensors
$5 K
$1.0 K
Computer and
Interfaces
Installation/ Integration
$5 K
$1.0 K
$0.5 K
$0.2 K
Total
$13 K
$2.7 K
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Automatic Longitudinal Control in
Platoons
• Accurately control truck speed and spacing
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•
•
•
behind lead truck, using sensors and wireless
communication between trucks
Significantly increase capacity per lane,
avoiding need to build extra lanes
Reduce aerodynamic drag, saving fuel and
emissions
Smooth out accel/decel cycles to save fuel,
emissions and wear and tear on truck and
cargo
Benefits only gained in exclusive lane
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Longitudinal Control Cost per Truck
Forward sensors
Near term
(hundreds of
trucks)
$2.5 K
Long term
(thousands
of trucks)
$0.5 K
Wireless communication
$0.5 K
$0.1 K
Brake actuation
$5.0 K
$1.0 K
Driver interface
$1.0 K
-
Installation/ Integration
$1.0 K
$0.3 K
Total
$10 K
$1.9 K
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Fully Automated Driving
• Combine automatic steering, speed and
spacing control
• Combine benefits and costs of above
systems
• Must operate in dedicated, protected lanes
• Potentially eliminate need for drivers in
following trucks of platoon (or greatly reduce
their workload), but would then need staging
areas for transitioning between automation
and normal driving
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Short-Term Alignment for Proposed
Truck-only Roadway
$1.25
Total Length
71.6 km
$1.25
$1.25
$1.25
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Long-Term Truck Roadway Alignment
(using highway right of way)
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Operational Alternatives
• Alternative 1 – Baseline (“Do-Nothing”)
– No truck-only lanes and no CVHAS
– Does include programmed or planned projects
• Alternative 2 – Truck-only lane without CVHAS
– Open to all trucks
– Assumed open at Year 2005;
– One standard 12-foot lane in each direction before Year
2015 (based on the predicted traffic volume to be
presented later), and a second lane added on segments
from the State Line to I-294 by Year 2015;
– Benefits: provide an alternative truck route and relieve
network congestion.
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Operational Alternatives (Cont’d)
• Alternative 3 – Exclusive lane for automatically-
steered trucks
– Truck-only lanes,with automatic steering for
equipped trucks only;
– Including check-in and check-out locations;
– One 10-foot lane in each direction (plus shoulders);
– Incremental benefits: savings of construction and
ROW costs;
– No increase of capacity;
– No need for the second lane based on expected
market penetration of equipped trucks (assumed
3000 equipped trucks at Year 2005, and the number
grows continuously to be 20,000 at Year 2025)
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Operational Alternatives (Cont’d)
• Alternative 4 –Exclusive lanes for automated
trucks
– Truck-only lanes with automatic steering, automatic
speed and spacing control with 2 or 3 truck platoons
if warranted for automated trucks only;
– Including check-in and check-out locations;
– One 10-foot lane in each direction (plus shoulders);
– Incremental benefits
• Savings of construction and ROW costs;
• Savings of fuel and emissions;
• Increase of capacity and thus no need for the second
lane;
– Assumed 1900 equipped trucks at Year 2005, and the
number grows continuously to be 20,000 at Year 2025
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Operational Alternatives (Cont’d)
• Alternative 5 – Time-staged addition of
automation to truck-only lanes
– Truck-only facility without CVHAS technologies before
–
–
–
–
Year 2015;
At Year 2015, convert the facility to an automated truckway for equipped trucks only (automatic steering,
speed and spacing control with 2 or 3 truck platoons);
One 12-foot lane in each direction (plus shoulders);
No savings of initial construction and ROW costs;
Advantages
• Equipped cost per vehicle would be much lower and
traffic demand higher.
• Assumed 18,000 equipped trucks at Year 2015;
• No need for the second lane due to platooning
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Traffic Analysis Results for Tolled Truck Lane
(Year 2005 at Selected Links)
Network Daily Statistics
Private Auto
(Baseline)
Private Auto
(Alternative 2)
Difference
Heavy Truck
(Baseline)
Heavy Truck
(Alternative 2)
Difference
Vehicle Miles Traveled
Vehicle Hours Traveled
All Facilities Free/Expressway All Facilities Free/Expressway
159,644,571
40,545,003
7,319,636
1,325,469
159,635,502
-0.0%
All Facilities
6,741,155
40,826,589
7,268,434
0.7%
-0.7%
Free/Expressway All Facilities
4,264,104
204,843
1,323,007
-0.2%
Free/Expressway
94,617
6,765,553
4,367,236
196,986
91,325
0.4%
2.4%
-3.8%
-3.5%
Time savings!
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Costs and Benefits Compared to
Baseline (Do Nothing)
Units: $ million
Cost Components
Construction costs
ROW costs
Annual O&M
CVHAS costs (facility)
CVHAS costs (vehicle)
Total
Benefit Components
Travel time savings
Reduction of fuel
consumption
Total
B/C ratio
Alternative 2
(Without
CVHAS)
Alternative 3
(Automatic
Steering)
Alternative 4
(Fully
Automated)
Alternative 5
(Time-staged
Automation)
692
74
14
0
0
780
424
48
15
0.4
146
634
424
48
16
1.6
269
758
459
52
15
0.8
40
566
2,938
2,186
1,931
2,982
10
2,949
8
2,194
49
1,980
28
3,010
3.78
3.46
2.61
5.32
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Observations
• All new truck lane alternatives look cost effective
compared to base case
• Truck-only facility was not fully utilized in
Alternatives 3 (automatic steering) and 4 (fully
automated) due to limited market penetration of
CVHAS equipped trucks
• Alternative 5 looks best since it deploys CVHAS
technologies later, when vehicle costs are lower and
traffic volumes higher
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Conclusions
• Compared with the baseline, all dedicated truck
lane alternatives should be cost effective (B/C
ratios between 2.61 and 5.32)
• Alternative 5 was evaluated as the best because
it deployed CVHAS technologies later, when
their costs were lower and the traffic volumes
larger. The incremental CVHAS B/C ratio is 7.57
relative to the truck-only lane without CVHAS
technologies.
• CVHAS technologies are able to help improve
the performance of the freight system. However,
the times and ways of deploying CVHAS
technologies are important to their efficiency
and success.
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