Education

Titel

Merging into a Demo 2000 Platoon

Naam

Gertjan Tillema

Stagebegeleiding

Prof. Dr. Ir. Bart van Arem (Universiteit Twente)

Prof. Dr. Ir. Sadayuki Tsugawa (National Institute of Advanced Industrial Science and Technology (AIST)

Afronding stage

Augustus 2006

Stagebedrijf

National Institute of Advanced Industrial Science and Technology http://www.aist.go.jp/

In this research the differences between the effects of Demo 2000 vehicles and free agents merging into Demo platoons are determined. The Demo 2000 platooning system is developed as a flexible platooning system. This means it can drive autonomous on existing highways, build and split platoons and can handle merging and leaving vehicles.

To study the differences in effects on Demo 2000 platoons between merging free agents and Demo 2000 vehicles and in terms of capacity and comfort a model is build in Matlab/Simulink. This model contains a main lane and an on-ramp. The main lane contains four Demo 2000 platoons, each containing ten vehicles. On the on-ramp, eight vehicles merge into the platoons. Three scenarios are used to determine the effects: only Demo 2000 vehicles merge into the platoons, 50% of the merging vehicles is Demo 2000 vehicle, the others are free agents and the last scenario contains only free agents on the on-ramp. Each scenario is run with a headway of 50, 75 and 100 meter, for the merging vehicles and as the inter platoon distance. To reduce the influence of extreme peaks, each run is repeated three times, each time with different random seeds for a lot of parameters.

To model the Demo 2000 system accurate, an analysis is made of the system. The phenomenon of string stability got a lot of attention, because it showed up that to both ensure string stability and ensure comfort and safety is very hard. With the control gains used during the demonstration in 2000 it isn't possible to create stable platoons at a speed around 25 m/s. By changing the control gains it became possible to drive 25 meters per second with 25 meters headway and let Demo 2000 vehicles and free agents merge safe and comfortable.

The results show that if a larger part of the merging vehicles is equipped with the Demo 2000 system an increase in capacity and comfort is expected. But to reach the effects, a large part of the vehicles needs to be equipped with the system: when 50% of the vehicles is equipped, the increase in capacity was just over 5%. If 100% of the vehicles is equipped, an increase of 30% was found.

To get good results from platooning systems in terms of capacity and comfort, it is essential to realize that the fast majority of the vehicles needs to be equipped with the Demo 2000 system, else the positive effects will be only a fraction of what could be reached.