Stefan Hausberger

The impact of traffic-light-to-vehicle communication on fuel consumption and emissions

“Smart” vehicles of the future are envisioned to aid their drivers in reducing fuel consumption and emissions by wirelessly receiving phase-shifting information of the traffic lights in their vicinity and computing an optimized speed in order to avoid braking and acceleration maneuvers. Previous studies have demonstrated the potential environmental benefit in small-scale simulation scenarios. To assess the overall benefit, large-scale simulations are required. In order to ensure computational feasibility, the applied simulation models need to be simplified as far as possible without sacrificing credibility. Therefore this work presents the results of a sensitivity analysis and identifies gear choice and the distance from the traffic light at which vehicles are informed as key influencing factors. Our results indicate that a suboptimal gear choice can void the benefits of the speed adaptation. Furthermore, we present first results of a scale-up simulation using a real-world inner-city road network and discuss the range in which we expect the saving in fuel consumption to be in reality.

Can V2X communication help electric vehicles save energy

Battery electric vehicles (BEV) are envisioned to play a significant role in the future of personal mobility. A key challenge in the transition from internal combustion engine (ICE) powered vehicles to BEV is the limited driving range of the latter, which makes an energy-efficient operation essential. In this work, we analyze how vehicle-to-x (V2X) communication, in particular traffic-light-to-vehicle communication (TLVC), can help the drivers of BEVs save energy and thus increase driving range. Furthermore, we analyze factors impacting energy consumption which are relevant to the design of V2X applications for BEV. Our results indicate that TLVC can significantly reduce the energy consumption of BEV, up to 20% in our setup. The actual result, however, is highly dependent on a combination of traffic situation, communication range, auxiliary consumer power demand, road gradient and minimum speed requirement.

Emission behaviour of modern heavy duty vehicles in real world driving

Within a national and two international research projects, a vehicle emission model was developed, which calculates emissions in real world driving from the engine emission maps by simulating engine power and engine speed. Influences of transient load changes on the emission level are taken into consideration by special functions. Model parameters are gained from a common measurement protocol on 72 engines. A main conclusion of the work was that EURO 2 and, to a smaller extend, EURO 3 HDV show significant higher NOx emission in real world driving than in the type approval tests.

Recent NiMH-battery modeling supported by finite element thermal analysis

The performance of Ni-MH batteries powering hybrid vehicles is mainly influenced by its operating conditions. A sophisticated battery management is necessary to maximize performance as well as life time. So an adequate battery model is required. This contribution deals with the design of such a model. To begin with a common electric circuit model of the battery is used. Variant battery characteristics given by the data sheet have been dressed into analytical expressions which will feed the electric network. Of substantial interest for all network parameters is the knowledge of the battery temperature. With the aid of the finite element method, variant ambient and cooling conditions have been simulated in advance. Therefrom, the temperature behavior could be considered in the model. With the use of a real life driving cycle, wherein the power request as well as the energy recuperation during a specified time period are given, the battery model has been proved.

Future HD vehicle requirements due to legislation and effects on CO2 and air quality

The actual EURO VI regulation based on WHTC, WHSC and on on-board emission tests led to very low emission levels of HDV also in real driving conditions. Consequently the focus of the development will shift more and more towards low CO2 emissions and better fuel efficiency.