t tno inro chania, 14 march 2002paul van koningsbruggen & rick van der arend 1 distributed...
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Chania, 14 March 2002Paul van Koningsbruggen & Rick van der Arend
1
tTNO Inro
Distributed Control from policy statements to local traffic control
Presentation at the OMNI-workshop
Chania, 14 March 2002
Towards a Concept for Distributed Control 2t
Content
• The Idea behind Traffic Management in The Netherlands
• Linking Network Policy and Local Practice• A concept for Distributed Control
Chania, 14 March 2002
Towards a Concept for Distributed Control 3t
The objective is a common traffic management approach
Elst
Arnhem
A12
A15
A12
A50
A50
A348
N325N225
N224
N785
N348
Urban RoadInter-urban RoadMotorwayRiver
VelpTrajectory speed 60 km/h
Less traffic in the city
Regional traffic only
Less traffic regarding construction works
Chania, 14 March 2002
Towards a Concept for Distributed Control 4t
Three Optima for Traffic Management
Network Optimum
User Optimum
Policy Optimum
Social & Economical Context
Utilisation of the Infrastructure
Individual Preferences Road Users
Traffic Management
Strategy
Chania, 14 March 2002
Towards a Concept for Distributed Control 5t
When the infrastructure capacity is insufficient to meet traffic demand …….
• Today’s reality: choices have to be made in the allocation of the scarcity in infrastructure capacity
Traffic Management Strategy
• Three Main Research Questions:• How can we balance the three optima and translate them into
operational goals for traffic control systems?• How can we balance the optimum on a network level and the
local, situational optimum?• How can we get the traffic control strategy to focus on the actual
traffic flows
Positioning services (measures)
Guide operations
Chania, 14 March 2002
Towards a Concept for Distributed Control 6t
The Idea is to link Network Policy and Local Practice
Network Traffic
Management Strategy
‘What we aim at’
Balancing the three optima in a control
strategy
Traffic Management
Tactics
Balancing the operation of traffic
control systems
‘What we gain’
Local Goals &Best Practices
Practice
Policy
Chania, 14 March 2002
Towards a Concept for Distributed Control 7t
The Blueprint for the Traffic Management Concept
Momentary Network Policy: priorities and quality levels
Operational Traffic Control a.o. Traffic Management Tactics
Traffic
Traffic State
Monitoring Data &Local, situational restrictions
Momentary ‘Reference Scheme’
Signals
= ‘translation’
TN
TL
Chania, 14 March 2002
Towards a Concept for Distributed Control 8t
Network Policy: assigning priorities and defining quality levels to strive for
Chania, 14 March 2002
Towards a Concept for Distributed Control 9t
Two possibilities for the Traffic Management Tactics
• Traffic Management Tactics: IF …A… THEN …B…
• Option 1: • A = State of the Network• B = set of traffic management measures• Direct activation of the traffic management measures
• Option 2: • A = State of the Network• B = Set of priorities and Quality Levels • Autonomous activation of the traffic management measures,
within the context of (B) Distributed Control
Chania, 14 March 2002
Towards a Concept for Distributed Control 10t
Linking Network Policy and Local Practice by using ‘Gerdien’ Tower Model
Network
TrajectoryTrajectory
SegmentSegment Segment
LinkLinkLinkLink
PointPoint PointPoint Point
Intersection
Trajectory Node
Segment Node
Link Node
Priorities & Quality Levels
(Situational) Constraints
Chania, 14 March 2002
Towards a Concept for Distributed Control 11t
The Quintessence of the proposed ‘Distributed Control’ Approach
Plausible Approach
Proposed Approach
RM 1 RM 2 RM n
Ramp MeteringManagement System
TL 1 TL 2 TL n
Traffic LightManagement System
VMS 1 VMS 2 VMS n
VMSManagement System
Traffic Manager
DN1 DN2 DNn
Partial Networks
T1 T2 Tn
Trajectories
S1 S2 Sn
Segments
L1 L2 Ln
Links
Traffic Manager
Chania, 14 March 2002
Towards a Concept for Distributed Control 12t
The idea is to co-ordinate local goals within the context of the network policy
Three (or more?) paradigms:• Industrialisation
• hierarchical order; command and control structure from network level to link level
• Arbitration:• conflicts on lower level will be referred to arbitration on a
higher (network) level
• Utilitarianism• negotiation on lower level, while adhering to a mutual, higher
network goal
Distributed Control based on the Multi-Agent Principles
Chania, 14 March 2002
Towards a Concept for Distributed Control 13t
DECISION
EVALUATIONOBSERVATION
ACTION
'TRAFFIC'
Cycle of Information Processing in the Kernel of an Agent
Chania, 14 March 2002
Towards a Concept for Distributed Control 14t
Link-Agent 2
Link 1
Service-Agent
Constraints
Link 2
Link-Agent 1
Traffic
Data
Traffic
DataImpact on Link
1
Impact on Link
2
Local, Network Goal
Local, Network Goal
Two Type of Logical Agents: infrastructure Agents and Service Agents
Zuidpolder, 4 Maart 2002
Agents in Verkeersbeheersing 15t
Link Agents observe en evaluate the local traffic situation and decide the required improvements in terms of ‘basic controls’ (e.g. I - V - C) and ask the relevant Service Agents for these improvements.
In case the local services are not sufficient anymore, the Link Agents start to negotiate, to gain the improvements together.
Operation of the Link Agents
Zuidpolder, 4 Maart 2002
Agents in Verkeersbeheersing 16t
Service Agents observe and evaluate incoming claims of Link Agents within their sphere of influence. Then, the Service Agents decide how to activate the actuators (traffic management systems) in order to meet with as many claims as possible.
On a network level, the Service Agents negotiate, in order to co-ordinate the actuators.
Operation of the Service Agents
Chania, 14 March 2002
Towards a Concept for Distributed Control 17t
Link Claims
Activating Actuators
Distributed Controller
Infrastructure Network
Communication
Resulting in a Concept for Distributed Control
Zuidpolder, 4 Maart 2002
Agents in Verkeersbeheersing 18t
State of Research:implementation of the distributed concept for a Motorway Stretch with Ramp Metering
Scenario 1: no ramp metering
Scenario 2: individual ramp metering (‘Alinea’ algorithm)
Scenario 3: distributed control, node as sphere of influence
Scenario 4: distributed control, complete motorway stretch as sphere of influence
Chania, 14 March 2002
Towards a Concept for Distributed Control 19t
Resume
• The Idea behind Traffic Management in The Netherlands
• Linking Network Policy and Local Practice• A concept for Distributed Control