ROS
  • Introduction
  • First Chapter
  • chapter2
  • chapter3
  • Docker + ROS
  • ND - 2. ROS essentials - core
  • ND - 2. ROS essentials - run
  • ND - 3. Kinematics - core
  • C++ beginner s2-basic
  • c++ beginner s3-function
  • c++ beginner s4-class
  • c++ beginner s5-pointer
  • PKG - navigation
  • PKG - tf
  • PKG - move_base
  • PKG - actionlib
  • PKG - amcl
  • PKG - costmap_2d
  • Debug
  • ND2 - Project 2 - localization - basic
  • ND2 - Project 2 - localization - files
  • ND2 - Project 2 - localization - writeup
  • ND2 - Project 2 - localization - ruby
  • ND2 - project - Deep RL manipulator
  • ND2 - project - path planning
  • Write up
  • hsr
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  • actionlib
  • Client-Server Interaction
  • Goal
  • Feedback
  • Result
  • .action file

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PKG - actionlib

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Last updated 5 years ago

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actionlib

Service can: send a request to a node to perform some task, and also receive a reply to the request.

actionlib = Service + long executing time (ability to cancel the request or get periodic feedback)

Example:

  • moving the base to a target location

  • performing a laser scan and returning the resulting point cloud

  • detecting the handle of a door

Client-Server Interaction

The ActionClient and ActionServer communicate via a "ROS Action Protocol", built on top of ROS messages.

The client and server provide a simple API for users to request goals (on the client side) or to execute goals (on the server side) via function calls and callbacks.

Goal

ActionServer -> goal (msg) -> ActionClient

Feedback

ActionServer -> goal (msg: progress) -> ActionClient

Result

When completion of the goal, ActionServer -> goal (msg: once) -> ActionClient

.action file

# Define the goal
uint32 dishwasher_id  # Specify which dishwasher we want to use
---
# Define the result
uint32 total_dishes_cleaned
---
# Define a feedback message
float32 percent_complete