How to use the action interface of franka_ros packages

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Hello,

first of all: I am an absolute ROS beginner so excuse my silly question. I am trying to operate the Franka Emika Robot Panda using ROS.

Here the documentation: https://frankaemika.github.io/docs/ro...

I operated it previously using MoveIt but now i would like to use franka_ros directly for instance to move the gripper. I started the respective node using:

roslaunch franka_gripper franka_gripper.launch robot_ip:=<fci-ip>

In the docu it states that now different action servers can be used e.g. franka_gripper::HomingAction(). But what exactly do I have to do now for example to home the gripper. Do I have to use the code part franka_gripper::HomingAction() and if so where do I have to put it in? Do I have to start an action Server first?

I did some reading but somehow I can't figure out how this basic structure works.. Thanks in advance for any help and explanations!!

Edit: Thanks for your answer. Apparently I was on the right track. However, I was not sure wether I needed to write the action server myself. Now I wrote an action client.

I included the following into my action client:

#include <ros/ros.h>
#include <actionlib/client/simple_action_client.h>
#include <franka_gripper/franka_gripper.h>
#include <franka_gripper/HomingAction.h>

Within the main method I wrote:

ros::init(argc, argv, "ros_test_client";
actionlib::SimpleActionClient<franka_gripper::HomingAction> ac("franka_gripper/homing", true);
ROS_INFO("Waiting for action server to start");
ac.waitForServer();
ROS_INFO("Actin server started, sending goal");

However, when I am running the action client it only gets to the point where it returns "Waiting for action server to start". So apparently the action server is not yet started.

Reading ( https://frankaemika.github.io/docs/ro... ) I thought

roslaunch franka_gripper franka_gripper.launch robot_ip:=<fci-ip>

would do the job. Apparently it is not. I tryed to start the node independly by: rosrun franka_gripper franka_gripper_node Robot_ip:=<fci_ip> In that case I get the error:

terminate called after throwing an instace of 'ros::InvalidNameException' what(): Character [1] is not valid as the first character in Graph Resour Name <fci-ip>