RTT Actionlib

Actionlib action servers provide the following interfaces, and actionlib action clients reciprocate:

• Inputs:
  • Goal topic
  • Cancel topic
• Outputs:
  • Status topic
  • Feedback topic
  • Result topic (per goal)

For an Orocos RTT component to provide an actionlib interface, it needs to provide the topics described above. In order to expose actionlib interfaces to components running in real-time threads, we should use the rtt data ports to connect to these topics. In order to make it easy to connect these ports, this package provides a C++ API for constructing the appropriate RTT data ports and an RTT service for connecting those ports to ROS topics if necessary.

Contents

This package provides a C++ API and RTT service for constructing and connecting several RTT ports to a ROS actionlib action namespace.

Providng Actions from Orocos

In the standard ROS actionlib server, subscribing and publishing ROS messages on the actionlib topics are handled automatiaclly by the ActionServer class, and users are meant to delegate to an instance of this class. ActionServer then calls short-running “goal” and “cancel” callbacks when it receives the appropriate messages. It is in these user-supplied callbacks that goal handlesare set to be accepted/rejected or preempted, respectively.

The user sets the status of these handles by calling member functions setSucceeded(), setAborted() etc. on the handles. These calls then call the parent ActionServer’s publishResult(),publishStatus() etc. member functions. The “normal” ActionServer implements these functions with ROS publishers and subscribers, but for RTT, we want these to use data ports.

To this end, we implement an RTTActionServer C++ class which inherits from ActionServerBase and implements the “publish” functions with RTT data ports and binds the goal and cancel callbacks to RTT event ports.

Calling Actions from Orocos

TBD

Usage

First the appropriate RTT ports need to be created in a given service (or subservice) of a TaskContext. These can be easily creted by delegating to an RTTActionServer. The RTTActionServer will create the necessary RTT ports and bind them to the user-supplied callbacks. For example, to add an actionlib interface to a given compnent, you could do something similar to the following:

```cpp class SomeComponent : public RTT::TaskContext { private:

// Convenience typedefs typedef actionlib::ServerGoalHandle<some_msgs::SomeAction> GoalHandle;

// RTT action server rtt_actionlib::RTTActionServer<some_msgs::SomeAction> rtt_action_server_;

public:

// Component constructor SomeComponent(std::string name) : TaskContext(name, RTT::PreOperational) { // Add action server ports to this task’s root service rtt_action_server_.addPorts(this->provides());

// Bind action server goal and cancel callbacks (see below)
rtt_action_server_.registerGoalCallback(boost::bind(&SomeComponent::goalCallback, this, _1));
rtt_action_server_.registerCancelCallback(boost::bind(&SomeComponent::cancelCallback, this, _1));   }

// RTT start hook bool startHook() { // Start action server rtt_action_server_.start(); return true; }

// RTT update hook void updateHook() { // Pursue goal here }

// Called by rtt_action_server_ when a new goal is received void goalCallback(GoalHandle gh) { // Accept/reject goal requests here }

// Called by rtt_action_server_ when a goal is cancelled / preempted

File truncated at 100 lines see the full file

Changelog for package rtt_actionlib

2.9.2 (2019-05-15)

2.9.1 (2017-11-16)

2.9.0 (2017-05-02)

• Added deprecation warning for header rtt_roscomm/rtt_rostopic.h and updated some include directives within rtt_ros_integration
• Added individual changelogs and bumped versions to 2.9.0
• Contributors: Johannes Meyer

2.8.6 (2017-11-15)

2.8.5 (2017-03-28)

2.8.4 (2016-11-26)

2.8.3 (2016-07-20)

2.8.2 (2015-06-12)

• see rtt_ros_integratoin/CHANGELOG.rst