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1 Create Way
Singapore, 138602

Research project within TUM CREATE. Focussing on modelling and optimisation of architecture and infrastructure, urban systems simulation like traffic and power are the main research interests. Apart from that, a cognitive systems group deal with human computer interaction. 


Filtering by Category: Simulation

CityMoS and Veins - Car to Car Communication

Michael Wagner

Veins (Vehicles in Network Simulation) is an open source framework for simulating wireless network communication between road-going vehicles and infrastructure, such as traffic lights. Veins originated as a specialized application of the OMNeT++ network simulation library, which supports highly detailed network models covering the complete network stack down to the physical layer. SUMO is the first traffic simulation that supports coupling with Veins, which is solved by the so called TraCI protocol.

The TraCI Protocol

The protocol defines how a TCP connection is established between Veins and a traffic simulation, as well as the contents of the packages sent between both ends. The traffic simulation acts as the TraCI server, and waits for a network simulation (Veins), acting as a TraCI client, to initiate the TCP connection between both. Once the connection is established Veins takes control of the simulation flow by creating a continuous feedback loop between traffic and communication to accurately portray the effects of communication on the urban system.

As of version 1.5.5 CityMoS received its own implementation of the TraCI protocol, which allows it to run as a TraCI server in three different ways:

Blocking server

$ ./CityMoS --traci

Running as a TraCI server without additional parameters prompts CityMoS to start up and wait until an instance of Veins has connected. No simulation work will be done before that.

Timed blocking server

$ ./CityMoS --traci = 5

Running as a TraCI server with an additional time argument prompts CityMoS to start up, perform simulation until the given time and then to wait for incoming Veins connections. Once established, the traffic and network simulations are running in unison. This is the most common use case of simulation coupling where the CityMoS side is guaranteed some warm-up time until it reaches a steady state. Doing so ensures that recorded data is free of artifacts that may occur during the startup phase of the simulation

Parallel server

$ ./CityMoS --traci = -1

Running as a TraCI server with any negative parameters prompts CityMoS to run the simulation while at the same time waiting for an incoming Veins connection. In this mode Veins can take charge of the traffic simulation at any time

Region of Interest

In many use cases it is not necessary or useful for the network simulation to geographically cover the entirety of the traffic simulation. For example, the user might only be interested in the effects on a certain district in town, save computational resources to increase performance or reduce the impact of boundary conditions by excluding the border areas from the feedback loop.

Veins, and by extension the TraCI protocol, allow the user to define a region of interest, which delimits the geographic area of the traffic simulation that will be considered for the network simulation.

How will the charging of electric vehicles affect Singapore’s power grid?

Vaisagh Viswanathan

The large-scale introduction of plug-in electric vehicles (PEV) may pose challenges to power system operators by causing grid congestion or voltage fluctuations. In a previous post we presented a simulation framework consisting of a traffic simulation coupled to a power system simulation allowing investigating the impact of electric vehicle charging on the power grid. In this post we present a first application of this approach to the case of Singapore.

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First glimpse of the effect of uncertainty on charging behaviour

Vaisagh Viswanathan

As an application to the previous article, we examine how uncertainty influences charging behaviour. Due to limited range and long charging time of electric vehicles (EVs),  the range anxiety phenomenon occurs in situation where the user might not reach the destination when low on battery (M. Nilsson 2011). While internal and personal factors are important factor regarding range anxiety (N. Rauh et al. 2014), we focus on external factors. Understanding charging behaviour will enable more optimal deployment of charging stations. In this article, the effect of uncertainty on charging behaviour is addressed using  a serious games approach or a game-based experiment.

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Real Time Traffic State Estimation And Short Term Prediction

Daniel Zehe

Increasing availability of floating car data both historic and in the form of trajectory datasets and real-time in the form of continuous data stream paves way for data driven traffic simulations. Continuous data streams from floating cars along with historic datasets can be used for purposes such as current traffic state estimation, incident detection and predicting short term evolution of traffic using simulations.

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How the use of information affects traffic systems

Daniel Zehe

The availability of new real time traffic information sources and communication possibilities has increased in the recent years with a broader distribution of personal smart devices. An increasing number of traffic participants rely on navigation tools and applications on smart devices to access real time traffic information, forecasts, guidance and support. The flow of data goes in two ways. By using these applications to access information, the traffic participants provide data trough participatory sensing. In this context, there is a large amount of transportation data that is processed and the information is made available in real time to people.

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