A Task Model for Box-Pushing

They found that pushing a box involved a series of phases or steps, often executed in a repetitive manner.
A termites nest is constructed through a series of building steps. Each construction phase is thought to be governed by a building program with step transition specified as stimulus cues (i.e., communication through the environment---stigmergy).

Transport Controller

Box Detected Box Contact Subtask Controller

0 X Find-Box

1 0 Move-To-Box

1 1 Push-To-Goal

Find-Box

Touch? Contact? Avoid? Action

0 0 0 Random-Walk

0 0 1 Avoid

0 1 X Contact

1 X X Back-Off

Move-To-Box

Touch? Contact? Avoid? Box? Action

0 0 0 1 Seek-Box

0 0 1 X Avoid

0 1 X X Contact

1 X X X Back-Off

Push-To-Goal

See-Goal? Action

0 Reposition

1 Push-Box