Abstract. In a Wireless Sensor Network, sensor nodes may fail for several reasons and the network may split into two or more disconnected partitions. This may deteriorate or even nullify the usefulness and effectiveness of the network. Therefore, repairing partitions is a priority. In this paper we present a method to repair network partitions by using mobile nodes. By reasoning upon the degree of connectivity with neighbours, a mobile node finds the proper position where to stop in order to re-establish connectivity. Factors influencing the method performance are singled out and criteria for their selection are discussed. Simulations show that the proposed method is effective and efficient notwithstanding packet loss.

This paper discusses methods to avoid collisions between a robot and an obstacle, based on distance feedback given by a laser Time Of Flight (TOF) sensor. Two solutions are presented: the former (GCT: Geometry Consistent Trajectory) preserves the geometrical properties of the trajectory, while the latter (TCT: Time Consistent Trajectory) aims at preserving the time properties of the trajectory. Both the methods are validated on an experimental setup based on a two-head linear motor equipped with a commercial laser TOF sensor. Extension to a planar two d.o.f. manipulator equipped with a multiple beam sensor at the end effector is discussed as well.

The failure of sensor nodes could hinder the usefulness and the effectiveness of a WNS. In this paper we present a method to repair network partitioning by using a mobile node. By reasoning upon the degree of connectivity with neighbours, the mobile node finds the position where to deploy new sensor nodes in order to restore the network connectivity. Factors influencing the algorithm performance are discussed. Simulations show that the proposed method is effective and efficient not withstanding packet loss