Clustering in Urban Environments: Virtual forces applied to vehicles Leandros A. Maglaras (presentation) Dimitrios Katsaros University of Thessaly, Greece 1 IEEE ICC, Budapest (Hungary), 13th June 2013 1

Presentation outline Earlier work and background knowledge Virtual Forces applied to vehicles - VFVC Direction matters – Parameter Qd(t) Lane detection Performance evaluation Conclusions IEEE ICC, Budapest (Hungary), 13th June 2013 2

Clustering in Urban Envirnments Characteristics Intersections Mobility patterns More complex metrics Methods Affinity propagation APROVE Density based clustering Distributed group mobility adaptive clustering (DGMA) Spring Clustering IEEE ICC, Budapest (Hungary), 13th June 2013 3

Contributions • Virtual Forces Vehicle Clustering (VFVC) method (incorporation of local geographical characteristics in clusterhead election) • VFVC incorporates current position in clusterhead election (Lane detection) • Evaluation of the performance of VFVC under different network characteristics (density, velocity, car dimensions). IEEE ICC, Budapest (Hungary), 13th June 2013

Relative force among nodes l,m The concept of ‘Force directed algorithms’ Relative forces applied to nodes Forces are assigned as if the edges were springs and the nodes were electrically charged particles.The entire graph is then simulated as if it were a physical system Special role of nodes Relative force among nodes l,m Distance among nodes IEEE ICC, Budapest (Hungary), 13th June 2013 5

VFVC–characteristics that affect clustering • Vehicles that follow predefined routes like a bus (Qp) • Tall vehicles like trucks (Q) • Vehicles that follow non-turning lanes in a multi lane street (Qd(t)). • Vehicles that their driver behavior is statistically smooth (Qb). • Vehicles that mobility can be predicted (Qpr) Initial charge – same for all vehicles Total charge of vehicle (i) at time t IEEE ICC, Budapest (Hungary), 13th June 2013

Direction matters Beacon messages node Identifier (ID), node location, speed vector, total Force, state, time stamp, vehicle height and lane Clustering procedure • If the car follows a non turning lane ► Qd(t)=2 • If the car follows a turning lane ► Qd(t)=1 • If lane is going straight or turns the ► Qd(t)=1.5 IEEE ICC, Budapest (Hungary), 13th June 2013 7

Lane detection Lane detection system and a digital street map GPS + wheel odometer [A.Dean 2009] Beacon network ► triangulate vehicle position No GPS - real-time stereo vision [M. Bertozzi 1998] LIDAR - Light Detection and Ranging [M.Jabbour 2006] IEEE ICC, Budapest (Hungary), 13th June 2013 8

Evaluation setting (1/3) Virtual Forces Vehicle Clustering (VFVC) Impact of direction on a main street Competitors: Sp-Cl [appeared @ IEEE VECON’12], Low-Id, Mobic Measured quantities Average number of clusters (number of CHs) Average cluster changes / vehicle Average cluster lifetime IEEE ICC, Budapest (Hungary), 13th June 2013 9 9

Aggregation of roads - intersections Evaluation setting (2/3) Urban area of Volos Aggregation of roads - intersections Simulated urban area of Volos Route Distributions IEEE ICC, Budapest (Hungary), 13th June 2013 10 10

Evaluation setting (3/3) IEEE ICC, Budapest (Hungary), 13th June 2013

Impact of Lane detection in mean lifetime Direction expressed in terms of the street lane occupied by the vehicle is used in order to select the more stable clusterhead VFVC always performs better that the other methods IEEE ICC, Budapest (Hungary), 13th June 2013 12 12

Total number of clusters IEEE ICC, Budapest (Hungary), 13th June 2013 13

Average cluster changes / vehicle IEEE ICC, Budapest (Hungary), 13th June 2013 14

Summary Mobility in Urban Environments Lane detection - Direction matters Virtual Forces Vehicle Clustering (VFVC) Favors non turning vehicles to become clusterheads (due to staying longer on the road) Increases cluster lifetime Special role of vehicles is used to combine different characteristics - parameters of vehicles to improve the clustering performance IEEE ICC, Budapest (Hungary), 13th June 2013 15 15

Thank you! Clustering in Urban Environments: Virtual forces applied to vehicles Thank you! Leandros A. Maglaras (presentation) Dimitrios Katsaros University of Thessaly, Greece 16 IEEE ICC, Budapest (Hungary), 13th June 2013 16 16