This package defines a "task" (any high-level action) server node, utilizing ROS Actionlib, that:

• Accepts task action requests
• Interfaces with a user's defined Task Handler that
  1. Checks the validity of the task and
  2. Constructs and returns an instance of a task that implements the base AbstractTask
• Manages the life-cycle of your task, so creation, deletion, cancelation, abortion, failure, etc.
• Reports back failures and successes to the Action Client(s)

To use this package, you need to define a Python package called task_config with the following:

• A file called task_config where you define a CommandHandler and SafetyResponderclass.
  • SafetyResponder is used if Safety is enabled and the system goes into a safety response state.
• These classes need to implement the interfaces laid out here and here
• Each of your tasks also need to implement the AbstractTask defined here

• Action Server Name - Name of the action server to send requests to
• Safety Enabled - utilize the Iarc7 Safety Node Monitoring packages (see here for Iarc7 Safety)
• Update Rate - update rate of main state logic
• Startup Timeout - timeout on startup of node
• Force Cancel - if a task refuses to cancel, should the TaskManager force a cancel

• See the action folder for the action message types used for the Action Server

• Tasks are not trusted, so every task interaction is wrapped for protection; this means, unless the node is in a fatal state, a troublesome task will not bring down the TaskManager node
• Once a cancelation requests comes in, depending on the Force Cancel param, the behavior is the following:
  • If True:
    • The task is canceled, regardless if it returned False on task.cancel()
  • If False:
    • The current task is canceled if it returned True on the task.cancel() call; otherwise, it is allowed to continue running
• If a new action comes in while the current one is running, the behavior of the Actionlib is to make the server aware there is a new task available (and overwrite the pending action if a third action is requested before the first completes).
  • However, the TaskActionServer will check that the new action request has the preempt flag set to True
  • If so, the current task goes into a Cancel Requested state
  • If not, the current task is allowed to continue running until it completes and then the new task takes over

See here for an example Motion Task Config package setup.