Fig 1

Changing UAV formation for passing through a narrow area"

Fig 2

Relative motion relationship between leader and follower"

Fig 3

Relationship between formation error and performance function"

Fig 4

Safety judgment of formation change process"

Fig 5

Turning angle constraint"

Fig 6

Diagram of formation boundary"

Fig 7

Formation configuration space position"

Fig 8

Schematic diagram of algorithm space search"

Fig 9

Schematic diagram of trajectory segment for formation transformation"

Table 1

Map parameters m "

Fig 10

Schematic diagram of map"

Table 2

Relative position of followers in two formations m "

Fig 11

Trajectory of formation"

Fig 12

Simulation result of ${{\boldsymbol{e}}_{\boldsymbol{x}}}$ "

Fig 13

Simulation result of ${{\boldsymbol{e}}_{\boldsymbol{y}}}$ "

Fig 14

Simulation result of ${{\boldsymbol{e}}_{\boldsymbol{z}}}$ "

Fig 15

Simulation result of v "

Fig 16

Simulation result of ${\boldsymbol{\theta}}$ "

Fig 17

Simulation result of ${{\boldsymbol{\psi}} _{\boldsymbol{v}}}$ "

Fig 18

Simulation result of ${{\boldsymbol{a}}_{\boldsymbol{x}}}$ "

Fig 19

Simulation result of ${{\boldsymbol{a}}_{\boldsymbol{y}}}$ "

Fig 20

Simulation result of ${{\boldsymbol{a}}_{\boldsymbol{z}}}$ "

Fig 21

Simulation result of ${{\boldsymbol{e}}_{\boldsymbol{z}}}$ for Follower 3 "

Fig 22

Simulation result of ${{\boldsymbol{e}}_{\boldsymbol{y}}}$ for Follower 6 "

Fig 23

Formation trajectory with DSFC"

Fig 24

Comparison of ${{\boldsymbol{e}}_{\boldsymbol{y}}}$ for follower 6 using DSFC and the proposed PPFC "

Table 3

Start point and end point of leader"

Fig 25

Leader’s trajectory with c = 400 "

Fig 26

Leader’s trajectory with c = 0 "

Fig 27

Trajectory of formation"

Fig 28

Relative distance of X -axis "

Fig 29

Relative distance of Y-axis "

Fig 30

Relative distance of Z-axis "

Fig 31

Formation trajectory with DSFC"

Fig 32

Relative distance of X-axis "

Fig 33

Relative distance of Y-axis "

Fig 34

Relative distance of Z-axis "

Fig 35

Formation trajectory with ${\boldsymbol{l}} = {\boldsymbol{200}}\;{\bf{m}}$ "

Fig 36

Relative distance of X "

Fig 37

Relative distance of Y "

Fig 38

Relative distance of Z "