problem about travel task

HI:
I have made a model to let the agv to carry item from one queue to another, so i wirte the tasksequeue in trigger "Requst Transport From". In the tasksequeue, i used TRAVEL and MOVEOBJECT task, but the TRAVEL task doesn't work. I think this may have a relationship with DefaultNavigator, which i cannot find in the tree. now i want to know in what circumstance DefaultNavigator will appear and work? i know LOAD and FRLOAD task can Solve this problem, i just want to know something about DefaultNavigator. thanks advance.

It looks like only the transporter and operator will connect to and if necessary create a DefaultNavigator.

The reason (FR)LOAD and (FR)UNLOAD work is that they initiate offset travel that the class itself handles.

If you attach the TaskExecuter to a network it will be able to complete the TRAVEL tasks.

All this aside, if you don't use FRLOAD (your model uses MOVEOBJECT) then the objects will not be managing the capacity of the fixed resource objects correctly and you will have to cater for that yourself (it's usually important).