Satellite Mission Instruction Sequence Generation Algorithm Using a Flexible Weighted Directed Graph

Algorithm 2

An instruction sequence generation algorithm based on FWDAG.

1. The implement zone for the task starting node , The implement zone for all other nodes is set to ;

2. Starting from , select a node with degree (no precursor node) from the digraph as the current node . According to equation (2), calculate implement zone of all the backward nodes of the current node whose degree edges are connected.

3. According to Inference 2, the implement zone of the new node calculated by step 2 is updated by “And operation”. If the result of “And operation” is “Empty”, operation will be quit.

4. Deletes the current node and all flexible edges coming from this node.

5. Repeat steps 2 to step 4, until there are no more nodes in the directed graph.

6. Starting with , select a node from the directed graph with an outdegree of 0 (without a trailing node) as the current node , according to equation (3), select from according to the strategy of selecting node time (the last instruction is to select the earliest value, the start instruction is to be as late as possible, and the shutdown instruction is to be as early as possible), at the same time update the current node into all degrees edge connected to the precursor node implement zone;

7. According to Inference 4, the result of step 6 is updated by “And operation”. The result of “And operation” should not be “Empty”.

8. Deletes the current node and all flexible edges that enter this node.

9. Repeat steps 6 to step 8, until the node is no longer present in the directed graph.