ROS-robot-programming-book-by-turtlebo3-developers-EN

Posted 2021-01-09 sancai16888

The high level of English is a standard for a top student.

1. Some people are doomed to wait for others, some people are doomed by the human and so on. That sometimes all a person need is a hand to hold and a heart to understand.

2. No matter what happens, or how bad it seems today, life does go on, and it will be better tomorrow.

3. Living in this world, the biggest failure for you is not falling down, but it’s that you never become courageous enough to run. If you are not strict with yourself, life will turn hard on you.

4. Give people a chance to get to know you, and take time getting to know them. Love doesn‘t rush.

5. Be patient and tough; someday this pain will be useful to you.

6. This world, no one can go back to things including feelings. So we can only go straight.

7. Young people are still extremely limited in knowledge and experience, and they are lost in overflowing information. Information is not equal to outlook.

8. Sometimes you forgive people simply because you still want them in your life.

9. That wonderful world is waiting for me.

10. In my experience, some of the most successful relationships are based on lies and deceit. Since that is where you end up anyway, it is a logical place to start.

11. Cry as hard as you want to. But always make sure: when you stop crying, you’ll never cry for the same reason again.

12. Life has a value only when it has something valuable as its object. 

13. You say that you love the rain, but you open your umbrella when it rains. You say that you love the sun, but you find a shadow spot when it shines. You say that you love the wind, but you close the windows when it blows. This is why I‘m afraid, you said that you love me too.

14. We do not need magic to transform our world. We carry all the power we need inside ourselves already.

Reading books （154~235 page）

(http://www.pishrobot.com/wp-content/uploads/2018/02/ROS-robot-programming-book-by-turtlebo3-developers-EN.pdf)

note

1. When you input rqt, you should maximize the windows and move the mouse on the top so you can see the relative menu.

2. most frequently used: ‘rqt_image_view’, ‘rqt_bag’, ‘rqt_graph’ and ‘rqt_plot’.

3. rqt_image_view： display the image data of a camera

4. rqt_graph：The ‘rqt_graph’11 is a tool that shows the correlation among active nodes and messages being transmitted on the ROS network as a diagram.

Now that you have been introduced to ROS, let’s learn about ROS programming. The hottest keywords in the previous chapters were messages, topics, services, actions, and parameters. It is because these terms are the core of ROS. The node, which is the minimum execution unit, exchanges input and output messages between nodes through message communication on topics, services, actions, and parameters. In this chapter, we will learn about ROS programming with practical examples. 

5.  https://github.com/ROBOTIS-GIT/ros_tutorials/tree/master/ros_tutorials_topic

In this section, we have created a publisher and subscriber nodes that are used in the topic communication and executed them to learn how to communicate between nodes. The example source can be found at the following Github address:

If you want to run it right away, you can clone the source code with the following command in the ‘~/catkin_ws/src’ folder and build the source. Then run the ‘topic_publisher’ and ‘topic_subscriber’ nodes.

$ cd ~/catkin_ws/src
$ git clone https://github.com/ROBOTIS-GIT/ros_tutorials.git
$ cd ~/catkin_ws
$ catkin_make
$ rosrun ros_tutorials_topic topic_publisher
$ rosrun ros_tutorials_topic topic_subscriber

6.  https://github.com/ROBOTIS-GIT/ros_tutorials/tree/master/ros_tutorials_service

In this section, we have created the service server and the service client and executed them to learn how to communicate between nodes with service. Source codes for the example can be found in the following GitHub address:

If you want to run the example right away, you can clone the source code with the following command in the ‘~/catkin_ws/src’ folder and build it. Then run the ‘service_server’ and ‘service_client’ nodes.

$ cd ~/catkin_ws/src
$ git clone https://github.com/ROBOTIS-GIT/ros_tutorials.git
$ cd ~/catkin_ws
$ catkin_make
$ rosrun ros_tutorials_service service_server
$ rosrun ros_tutorials_service service_client 2 3

7.   https://github.com/ROBOTIS-GIT/ros_tutorials/tree/master/ros_tutorials_action

In this section, we have created action server and action client nodes and executed them to learn how to communicate between nodes. Related sources can be found in the following GitHub address:

If you want to run the example right away, you can clone the source code with the following command in the ‘catkin_ws/src’ folder and build the package. Then run the ‘action_server’ and ‘action_client’ nodes.

$ cd ~/catkin_ws/src
$ git clone https://github.com/ROBOTIS-GIT/ros_tutorials.git
$ cd ~/catkin_ws
$ catkin_make
$ rosrun ros_tutorials_action action_server
$ rosrun ros_tutorials_action action_client

 

A robot is largely classified into hardware and software. Mechanism, motors, gears, circuits, sensors are categorized as hardware. Micro-controller firmware that drives or controls the robot’s hardware, and application software that builds map, navigates, creates motion and perceives environment based on sensor data are classified as software.