[Package "my_dynamixel_workbench_tutorial" Not Running]

[Ashok12698]

ISSUE TEMPLATE ver. 1.0.0

Before you open issue, please refer to ROBOTIS e-Manual

1. How to setup? (ex, U2D2, OpenCR,...) 4 dynamixels 'XL430W250' connected in daisy-chain to RPi3 through U2D2

2. Which Dynamixel have you used? and how many? (Please describe below format to all connected Dynamixels)

   • Model Name XL430W250

   • ID 1, 2, 3, 4

   • Baud Rate of Dynamixels 57600

   • Protocol Version 2.0

3. Write down the commands you used in order

I am following this link to setup:
https://namesdir.com/mirrors/wiki.ros.org/dynamixel_workbench_controllers(2f)Tutorials(2f)VelocityControl.html

This commands I applied: 
$ cd ~/catkin_ws/src
$ catkin_create_pkg my_dynamixel_workbench_tutorial std_msgs roscpp
$ cd my_dynamixel_workbench_tutorial
$ mkdir launch
$ cd launch
$ gedit velocity_control.launch

launch file:
<launch>
  <arg name="device_name"      default="/dev/ttyUSB0"/>
  <arg name="baud_rate"        default="57600"/>
  <arg name="protocol_version" default="2.0"/>

  <arg name="left_idA"            default="1"/>
  <arg name="left_idB"            default="2"/>
  <arg name="right_idA"         default="3"/>
  <arg name="right_idB"          default="4"/>

  <param name="device_name"      value="$(arg device_name)"/>
  <param name="baud_rate"        value="$(arg baud_rate)"/>
  <param name="protocol_version" value="$(arg protocol_version)"/>

  <param name="left_idA"           value="$(arg left_idA)"/>
  <param name="left_idB"          value="$(arg left_idB)"/>
  <param name="right_idA"          value="$(arg right_idA)"/>
  <param name="right_idB"          value="$(arg right_idB)"/>

  <node name="velocity_control_example" pkg="dynamixel_workbench_controllers" type="velocity_control" required="true" output="screen"/>
</launch>

$ sudo chmod a+rw /dev/ttyUSB0
$ cd ~/catkin_ws && catkin_make
$ roslaunch my_dynamixel_workbench_tutorial velocity_control.launch
**'roslaunch my_dynamixel_workbench_tutorial velocity_control.launch'**

4. Copy and Paste your error message on terminal

![image](https://user-images.githubusercontent.com/11657541/83705730-aee41880-a650-11ea-95f0-cb3aaf22ba02.png)

SUMMARY
========

5. Please, describe detailedly what difficulty you are in

   • HERE I am unable to run this package 'my_dynamixel_workbench_tutorial' after build.

Is there anything I missed to check here. Please suggest. Thanks.