I know that in durative effects, I can compute based on #t, which is some flavor of elapsed time. But from the examples I see, it seems to be more like the duration of the effect itself: for instance, boil water, and heat it by a certain amount for the time it boils. Whereas, I want to have a cost that factors in total elapsed time since the start of the entire plan. Is that a different variable?
I tried (increase (total-cost) (* #t (num-not-yet-fixed ?group))) Where the num-not-yet-fixed goes down over time, and the idea is to increase the cost by a higher value if more things being "fixed" are fixed later rather than earlier. But (a) popf rejected the use of #t here, it seems, and (b) it seems like even if it worked, it would be for the fixed duration of the durative effect, and not since the start of execution.
Any chance you can create a new function, say (now), that starts at 0, is added to linearly over time via a full-plan envelope action, and then used by the other actions to refer to things?
Something like this...
(:durative-action measure-time
:precondition (begin)
:effect (and
(at start (going))
(at start (not (begin)))
(at end (not (going)))
(increase (now) #t)
)
; all other actions have a condition (over all (going))
; any action that needs to refer to the current time in the plan can use the function (now)
...and the init would have:
; used so that the measure-time happens only once
(begin)
; a function to measure the current time and use in an action
(= (now) 0)
...and the goal should be modified to also include (not (going))