ProLo: Localization via Projection for Three-Dimensional Mobile Underwater Sensor Networks

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. 2019 Mar 22;19(6):1414. doi: 10.3390/s19061414

Algorithm 1 ProLoAlg distributed localization and control algorithm.

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on node i:
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running ← true
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type MUWSN-Projection: {id, state, $p {x, y}$ , pt1, pt2, neighbors }
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// projection on the beacon plane, $p {x, y}$ : the coordinate vector
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//a sensor has 4 states: localized, flexible, rigid, localizable
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type neighbors[]:{id, state, d, $p {x, y}$ }
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//d: distance between the neighbor and this node
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$m o v e i d = 0$ // moveid: the times of moving epochs
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while running do
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//first part: localization
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if this node is beacon then
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state ← localized
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set up the beacon plane with the other two beacons
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else
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while not receiving the beacon plane from beacons do
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wait
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while globally rigid graph is not constructed do
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//Use TE to construct the globally rigid graph on the beacon plane
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run TE and initialize $r_{i} . p$ by distance vectors.
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if no enough parents then
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start contracting
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$r_{i} \leftarrow s e n s o r - P r o j e c t i o n$ //on this node i
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if $r_{i}$ .state is localizable then
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broadcast state and calculate the position
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$c a n d i d a t e s + =$ position() // use equations like Equations (6) and (7) to calculate new candidate positions
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if $| c a n d i d a t e s | > 2$ then
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$r i . p \leftarrow$ vote(candidates) //choose one candidate as the correct position
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state ← localized
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// second part: moving control
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if MUWSN is localizing then
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wait
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beacon starts moving: moveid ← moveid+1
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if received $m o v e i d$ from neighbors and $p_{i} . m o v e i d < m o v e i d$ then
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$p_{i}$ .move( $v_{i}$ )
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$p_{i} . m o v e i d = m o v e i d$
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state ← flexible
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if neighbor distance exceeds the threshold $T_{d}$ then
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start contracting
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if state == flexible then
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continue