Mobile robot trajectory planning for large volume data-muling from wireless sensor nodes

Mobile Data-Mule Optimal Path Planning for Wireless Sensor Networks

“…Regarding the service time that each MoEl spends in order to gather the stored data from the static node that it has visited, real time delays from our previous experimental work [33] are taken into account. In this work, the Rime communication stack [34,35] was adopted over the Contiki operating system [36].…”

“…Specifically, dist_vector is a vector that includes the distances per pair of static nodes and per MoEl and uniform speed = 0.2 m/s. In addition, v is a vector of v t j , which is the visiting time of the MoEl at a static node j and is defined by the static node's storage capacity and the corresponding required data transmission duration experimentally estimated in [33]. The static nodes profits are recalculated in every iteration of the MES scheme algorithm based on the Algorithm 4 and each profit is related to the edge x ijm that leads to the vertex j.…”

“…The vector v t j depends on the storage capacity of the static nodes defined in the presented scenario as the vector [0, 3, 8, 1, 2, 4, 5] for the set of static nodes expressed in Kbytes of stored data. The corresponding visiting time vector is [0, 24, 68, 7, 15, 34, 39] s based on [33]. The initial expiration time for the nodes is set as e_initial = [0, 1080, 1200, 900, 600, 720, 720] s. This vector denotes the frequency that every node has to be visited by an MoEl and hsa to transmit the stored data, due to these data criticality/storage limitations.…”

“…Finally, the time budget B that is set as a duration limit for the extracted routes is set as 360 s, while the charging duration value is 60 s. The optimization MILP problem was solved using Matlab's intlinprog routine of the Optimization Toolbox. It should be noted that the utilized storage WSN capacity and the download rate in setting the simulation parameters came from our previous work [33], where the communication protocol and data packet transfer were considered for a more realistic simulation study. The objective here is to evaluate the MES scheme efficiency and to investigate the number of data mules/MoEls that could guarantee no data loss within the network.…”