Mobile Sensor Deployment for a Dynamic Cluster-based Target Tracking Sensor Network Niaoning Shan and Jindong Tan Department of Electrical and Computter Engineering Michigan Technological university 2005 IEEE/RSJ International Conference on Intelligent Robots and Systems

Outline INTRODUCTION CLUSTER CONSTRUCTION MOBILE SENSOR DEPLOYMENT SIMULATION CONCLUSION

INTRODUCTION A hybrid sensor network  Most of the static sensors Contribute to the tracking task form a cluster By the target's current and future position  Mobile sensors Used to fill coverage holes inside the cluster Improve the tracking quality

INTRODUCTION

INTRODUCTION Group based mobile sensor deployment algorithm  To fill the coverage holes inside the cluster

CLUSTER CONSTRUCTION Cluster construction  For a sparsely deployed sensor network  Sensors outside the cluster area are needed for routing Because of the existence of Holes a n m b p

Holes and Hole Traverse A hole is defined as a face with more than 3 vertices Each sensor can locally decide whether it is on the edge of a hole  By checking its adjacent neighbor pairs Hole node  If any of its adjacent neighbor pairs is disconnected a n m b p Nodes a - p - b -n - m forms a hole

Holes and Hole Traverse Messages can be traversed to all nodes on a hole along the hole edges In order to easily terminate a hole traversing  a m n b p

MOBILE SENSOR DEPLOYMENT Sensors' sensing range is slightly larger than 1/2 of their communication range

MOBILE SENSOR DEPLOYMENT A greedy algorithm to deploy mobile sensors based on static sensor grouping  hole sensor grouping  mobile sensor local adjustment Group Members Property  Static sensors are grouped so that exactly one mobile sensor is needed To satisfy the condition in proposition 4.1

MOBILE SENSOR DEPLOYMENT The static sensors in group Gi are {Sj Gi | j = 1, 2,...,N Gi }  There exists at least one point Ci that the distances from Ci to Sj Gi, j = 1 2,...., N Gi are less than the sensors' communication range a b c d e f g h i j Ci

MOBILE SENSOR DEPLOYMENT Decision of the first group  They are sorted in clockwise direction to form a circular array Array H : a-b-c-d-e-f-g-h-i-j-a. a c d e f g h i j b

MOBILE SENSOR DEPLOYMENT Array H : a-b-c-d-e-f-g-h-i-j-a sensor starts searching for its candidate first-group members in this direction one by one Node a's first-group candidate is a - b - c Node i's first-group candidate is i- j - a - b - cwhich has 5 sensor nodes and bids 5 which has 3 sensor nodes and bids 3 first-group i- j - a - b - ctwo ends (terminators): i and c a b c d e f g h i j C1

MOBILE SENSOR DEPLOYMENT a b c d e f g h i j C1 C2 C3 Second group c-d-e-h-i Terminators h and e The grouping process is initialized by these two terminators The terminators of the previous group search group members for new group

MOBILE SENSOR DEPLOYMENT One terminator acts as the group head and the other one as group rear Two possible situations exist a c d e f g h i j C1 C2 b 1.Group head and rear overlap on one node 2.No more neighbors of head or rear can be incorporated into the group

MOBILE SENSOR DEPLOYMENT a c d e f g h i j C1 C2 b C3 one direction until no more sensors can be incorporated

Mobile Sensor Local Adjustment In order to best take use of the mobile sensors for tracking  Want the sensors to be evenly distributed  PS,i_k and PM,i_j are vectors from mobile sensor S M,i to one of its group member S S,k c mm is the desired distance between mobile sensors and set to be the communication range c, and cm are parameters for the virtual force generated by static sensors and mobile sensors

Mobile Sensor Local Adjustment The adjustment terminates at two possible situations  The force executing on a mobile sensor is 0  The mobile sensor cannot take care of all the group members after it moves

SIMULATION

CONCLUSION Deployment Algorithm enables mobile sensors  to fill coverage holes inside a dynamic cluster  Enhance the cluster's sensing capability