A two-level urban traffic control for autonomous vehicles · 2020-03-26 · A two-level urban...
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A two-level urban traffic control for autonomous vehicles to improve
network-wide performance
Tamás Tettamanti a, Arash Mohammadi b
Houshyar Asadi b, István Varga a
a Dept. of Control for Transportation and Vehicle Systems, Budapest University of Technology and Economics, Hungary
b Institute for Intelligent Systems Research and Innovation, Deakin University, Australia
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Motivation:- Manual versus autonomous vehicles- Also on traffic network level
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Autonomous vehicles at junctions autonomous intersection without physical traffic lights
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Junction traffic model
Ԧ𝑆 𝑘 + 1 = Ԧ𝑆 𝑘 + Ԧ𝑑 Ԧ𝑆 𝑘 ∙ 𝑣(𝑘) ∙ 𝑇
To avoid collision, condition 𝑑𝐴 − 𝑑𝐵 > 𝑑𝑚𝑖𝑛 must be
valid at all times.
This constraint is considered later in the control design.
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Emission model was also considered in the control design
• Traffic emission mainly consists of CO, NOx, HC, and CO2.
• For microscopic (vehicle based) emission the COPERT IV model was adopted:
𝑒𝑓 𝑣 = 𝛼2𝑝𝑣2 + 𝛼1
𝑝𝑣 + 𝛼0
𝑝,
where 𝛼𝑖𝑝
denotes the emission parameters for pollutant 𝑝
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Network traffic model
𝑛𝑧 𝑘 + 1 = 𝑛𝑧 𝑘 + 𝑇
𝑤,𝑧
𝛼𝑤,𝑧𝑞𝑤,𝑧 𝑘 − 𝑞𝑧(𝑘)
Macroscopic Fundamental Diagram (MFD)
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Two level optimizationusing SUMO traffic simulatorand MATLAB
Microscopic level optimization
Macroscopic level optimization
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Low level control in order to avoid collision
𝑚𝑖𝑛𝑢 𝑘+𝑙−1
𝐽 𝑘 ,
𝑠. 𝑡. 𝑢 𝑘 + 𝑙 − 1 ∈ 𝕌,𝑥 𝑘 + 𝑙 ∈ 𝕏,𝑙 = 1,2, … , 𝐾
𝐽 𝑘 =
𝑙=1
𝐾
𝑖=1
𝑁𝑣𝑒ℎ𝑖𝑐𝑙𝑒𝑠
𝛼 1 + 𝑝𝑖 𝑣𝑖2 𝑘 + 𝑙 + 𝛽 𝑣𝑖 𝑘 + 𝑙 − 𝑣𝑖 𝑘 + 𝑙 + 1 2 + 𝛾 𝑒𝑓𝑖
2 𝑣𝑖 𝑘 + 𝑙 ,
𝐷 = 𝑑𝑖𝑙 𝑁𝑣𝑒ℎ𝑖𝑐𝑙𝑒𝑠×𝐾 ,
min 𝐷 > 𝑑min
Constrained optimization
Highest mobilityLowest emission
Avoid collision
Nonlinear Model Predictive Control (MPC)
Priority parameter Acceptable distance
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Macroscopic level control
𝑝𝑧 = ൞
0, 𝑛𝑧 ≤ 𝑛𝑧∗
𝑛𝑧 − 𝑛𝑧∗
𝑛𝑧∗
, 𝑛𝑧 > 𝑛𝑧∗Priority parameter is calculated based on the MFD model:
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Simulations
MATLAB+SUMO (TraCI)
Prediction and control horizons = 20 seconds
MPC optimizer: nonlinear (fmincon)
http://www.dlr.de/
Test network with 4 intersections
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Visual results
Actuated
(time gap based actuated control)
Autonomous intersection control
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Results
The comparison of network mobility between the traditional and proposed methods.
+36%
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Results
The comparison of CO2 emission (based on HBEFA v3.1 data) between the traditional and
proposed methods.
-25%
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Conclusion and future work
• The performance of proposed control was justified:• High performance
• Higher mobility
• Lower emission
• Problems to overcome within the control design:• Disturbance can be present in the system, e.g. pedestrian crossing
• Solution for the transition period (when traditional and autonomous cars are running together)
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Thank you for your attention!!
www.deakin.edu.au/iisri
Institute for Intelligent Systems Research
and Innovation,
Deakin University
www.traffic.bme.hu
Dept. of Control for Transportation and
Vehicle Systems,
Budapest University of Technology and
Economics