Heuristic Scheduling Algorithm Oriented Dynamic Tasks for Imaging Satellites

Algorithm 1

The algorithm of IDI.

(1) Set values for 𝑚, dn

(2) Sort dynamic task set DT according to the priorities from low to high

(3) for all 𝑖∈[1,…,dn]  do

(4) for all 𝑗∈[1,…𝑚]  do

(5)  Compute all visible time windows of task 𝑖 observed by satellite 𝑗

(6)  Compute the number 𝑛^𝑗_𝑖 of the visible time windows

    of task 𝑖 observed by satellite 𝑗

(7) end for

(8) end for

(9) while DT is not empty do

(10)  Take the serial number 𝑖 of the first task in the queue

(11)  for all 𝑗∈[1,…,𝑚]  do

(12)   for all 𝑘∈[1,…,𝑛^𝑗_𝑖]  do

(13)    if thetimewindows[st^𝑗_𝑖,𝑘,et^𝑗_𝑖,𝑘]  does not conflict with others then

(14)    Inserting thetimewindows[st^𝑗_𝑖,𝑘,et^𝑗_𝑖,𝑘] directly

(15)   goto Step  9.

(16)   end if

(17)  end for

(18) end for

(19) for all 𝑗∈[1,…,𝑚]  do

(20)   for all 𝑘∈[1,…,𝑛^𝑗_𝑖]  do

(21)    Calucate the conflict degree of 𝑤^𝑗_𝑖,𝑘 with all time

     windows of the tasks scheduled

(22)   end for

(23) end for

(24) Selecting the minimum conflict degree, take the serial

   number of the satellite as min𝑗 and the serial number of the time window as min𝑘

(25) Deleting these scheduled tasks which time window

   conflict with the time window 𝑤^min𝑗_𝑖,min𝑘

(26) Adding them to the rear of the queue

(27) Inserting the time window 𝑤^min𝑗_𝑖,min𝑘 to the scheduled queue for task 𝑖

(28) end while