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Wang et al. Intell Robot 2023;3(4):538-64 I http://dx.doi.org/10.20517/ir.2023.30 Page 7 of 27

Figure 5. Definition of detection grid of i-th UAV.

 , <



 
(
= + − ) · − , ≤ <

 −

 , (6)

 ≥
√
( ⌈ ⌉) 2 ( ⌈ ⌉) 2

= − + −
2 2
where and are the maximum and minimum detection probabilities, and and are their

corresponding boundary detection distances. In order to comply with the actual detection situation, it is
assumed that the probability of a false alarm occurring during the detection process is ; that is, during a

motion cycle Δ , UAV may generate a false alarm signal within the detection range with a probability of .

Moreover, the additional conventions are given here:
(i) To avoid collisions between UAVs, at most one UAV is allowed to search within each mission grid cell at
any time instance.
(ii) Communications between UAVs are ideal, and there is no communication delay.
(iii) There is at most one target in a single mission grid cell.
(iv) After discovering the target, the UAV will detach from the search sequence, enter a tracking state, and
will not participate in subsequent search missions.
3. SEARCH INFORMATION MAP
When the mission area is discretized into grid cells, each search step of the UAV will be regarded as a search for
each corresponding cell and give feedback on the results, and search information maps can be used to express
the dynamic process of target search for each cell.

3.1. Probability map
A probability map is a search information map that reflects the existence probability of targets. Considering

the difference in speed between a UAV and a moving target, the mission grid Ω is refined and divided as the
region division of the probability map. After division, the mission area is divided into × grid cells with
as the side length of a single grid cell where ≤ , and the side length of a mission grid cell is times

of . Denote the grid of probability map as Ω , in which the cell with m-th row and n-th column is marked

as . Figure 6 shows the specific representation of the grid definition of a probability map.

Denote the existence probability of the target in as . Considering that the detection is carried out in a