cx_example_plugin

This package provides continuous execution of CLIPS environments. With a set frequency, this plugin refreshes all agendas and then runs the loaded CLIPS environments.

Usage

Register this plugin with the plugin manager. It’s configuration parameters are depicted in this example setup below.

clips_manager:
  ros__parameters:
    environments: ["main"]
    main:
      plugins: ["executive"]

    executive:
      plugin: "cx::ExecutivePlugin"
      # Publish an empty message with each agenda refresh.
      # Mainly useful for debug purposes to observe true refresh rate.
      # Defaults to false
      publish_on_refresh: false
      # With each iteration, insert the latest ros time into the CLIPS environment.
      # Defaults to true
      assert_time: true
      # Rate with which the environments should run in hz.
      # Note that this is only an upper bound, as it lets all environment
      # run until the Agenda is empty.
      # Defaults to 10
      refresh_rate: 10

CLIPS Features

This plugin adds deffunctions to retrieve the current time.

(bind ?ros-time (now))         ; returns a FLOAT holding get_clock()->now().seconds()
(bind ?sys-time (now-systime)) ; returns a FLOAT of system time

It additionally provides additional changes, if assert_time is true. Then it asserts an unordered fact time with the current ROS time, which looks like this:

(time 1729689959.63119)

It then also defines a defrule and defglobal to clean up the fact once the end of the agenda is reached:

(defglobal
  ?*PRIORITY-TIME-RETRACT*    = -10000
)

(defrule time-retract
  (declare (salience ?*PRIORITY-TIME-RETRACT*))
  ?f <- (time $?)
  =>
  (retract ?f)
)

Lastly, it unwatches both the time fact and time-retract rule as they otherwise would spam the log.

(unwatch facts time)
(unwatch rules time-retract)