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## note.0= [[dynamixel_controllers/Tutorials/ConnectingToDynamixelBus|connecting to Dynamixel bus]]
## descriptive title for the tutorial
## title =Creating a dynamixel action client controller
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## description = This tutorial describes how to create a joint controller with one or more Robotis Dynamixel motors.
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<<IncludeCSTemplate(TutorialCSHeaderTemplate)>>

<<TableOfContents(4)>>

All files that are created in this tutorial should be saved into my_dynamixel_tutorial package which we have created in [[dynamixel_controllers/Tutorials/ConnectingToDynamixelBus|previous tutorial]].

{{{
roscd my_dynamixel_tutorial
}}}
== Step1: Create a client ==
{{{#!python block=client
#!/usr/bin/env python
import roslib
roslib.load_manifest('my_dynamixel_tutorial')

import rospy
import actionlib
from std_msgs.msg import Float64
import trajectory_msgs.msg
import control_msgs.msg
from trajectory_msgs.msg import JointTrajectoryPoint
from control_msgs.msg import JointTrajectoryAction, JointTrajectoryGoal, FollowJointTrajectoryAction, FollowJointTrajectoryGoal



class Joint:
        def __init__(self, motor_name):
            #arm_name should be b_arm or f_arm
            self.name = motor_name
            self.jta = actionlib.SimpleActionClient('/'+self.name+'_controller/follow_joint_trajectory', FollowJointTrajectoryAction)
            rospy.loginfo('Waiting for joint trajectory action')
            self.jta.wait_for_server()
            rospy.loginfo('Found joint trajectory action!')


        def move_joint(self, angles):
            goal = FollowJointTrajectoryGoal()
            char = self.name[0] #either 'f' or 'b'
            goal.trajectory.joint_names = ['joint_1'+char, 'joint_2'+char,'joint_3'+char]
            point = JointTrajectoryPoint()
            point.positions = angles
            point.time_from_start = rospy.Duration(3)
            goal.trajectory.points.append(point)
            self.jta.send_goal_and_wait(goal)


def main():
            arm = Joint('f_arm')
            arm.move_joint([0.5,1.5,1.0])
            arm.move_joint([6.28,3.14,6.28])


if __name__ == '__main__':
      rospy.init_node('joint_position_tester')
      main()
}}}
==== The Code Explained ====
Now, let's break down the code piece by piece.

<<CodeRef(client,1,2)>> Library used for send a trajectory point

<<CodeRef(client,3,3)>> Remember to add the dependecies to your manifest

<<CodeRef(client,11,12)>> Library with action messages

<<CodeRef(client,19,20)>> Create a client through the topic namespace/name_of_server.In this case the namespace is self.name wich would be b_arm f_arm depends on witch arm do you wanna move, so remember to create a meta controller for b_arms and for f_arms, you can check this at [[dynamixel_controllers/Tutorials/Creatingmetacontroller|previous tutorial]].

<<CodeRef(client,28,29)>> Get the namespace first character that should be b or f and then add this to the trajectory joint names, that should match with joint names in your configuration file (config.yaml), you can review at [[dynamixel_controllers/Tutorials/Creatingmetacontroller|previous tutorial]].

<<CodeRef(client,39,39)>> send 0.5,1.5,1.0 positions for respectives joints joint_1x, joint_2x, joint_3x

== Step2: Executing a client ==
After you create the client you should launch the controllers and spawners created  in [[http://wiki.ros.org/dynamixel_controllers/Tutorials/Creatingmetacontroller|previous tutorial]].

{{{
roslaunch my_dynamixel_tutorial start_meta_controller.launch
}}}
and then execute the client

{{{
roscd my_dynamixel_tutorial
python trajectory_client.py
}}}
now see motors move in a trajectory!!