ROS编程（ETH）2018更新版习题说明（一）

课程1练习说明

主要内容（围绕这类复习）：

• ROS 体系结构
• ROS 主节点和主题
• 控制台命令
• Catkin工作区和编译系统
• 启动（launch）-文件

练习题：

1. 依据网页链接，完成Husky仿真环境配置，并启动。（ROS版本为Kinetic），可能需要源码编译。

说明：国内镜像测试并没有安装包，源码（https://github.com/husky/husky/tree/kinetic-devel）编译如下：

$ catkin build 

应该不会报错，但是执行时候会有问题，只要将缺失包安装就好。参考wiki说明进行操作。

$ export HUSKY_GAZEBO_DESCRIPTION=$(rospack find husky_gazebo)/urdf/description.gazebo.xacro

$ roslaunch husky_gazebo husky_empty_world.launch

$ roslaunch husky_gazebo husky_playpen.launch

$ roslaunch husky_gazebo husky_empty_world.launch world_name:=worlds/willowgarage.world 

2. 启动其中一个仿真，对下面命令进行练习和操作（对应第一课11-12页）。

rosnode list 、rostopic list 、rostopic echo [TOPIC] 、rostopic hz [TOPIC] 、rqt_graph。

relaybotbox@relaybotbox:~/tools/husky-simulation$ rostopic list /clock /cmd_vel /diagnostics /e_stop /gazebo/link_states /gazebo/model_states /gazebo/parameter_descriptions /gazebo/parameter_updates /gazebo/set_link_state /gazebo/set_model_state /husky_velocity_controller/cmd_vel /husky_velocity_controller/odom /imu/data /imu/data/accel/parameter_descriptions /imu/data/accel/parameter_updates /imu/data/bias /imu/data/rate/parameter_descriptions /imu/data/rate/parameter_updates /imu/data/yaw/parameter_descriptions /imu/data/yaw/parameter_updates /initialpose /joint_states /joy_teleop/cmd_vel /map /map_metadata /master_discovery/changes /master_discovery/linkstats /move_base/cancel /move_base/feedback /move_base/goal /move_base/result /move_base/status /move_base_simple/goal /navsat/fix /navsat/fix/position/parameter_descriptions /navsat/fix/position/parameter_updates /navsat/fix/status/parameter_descriptions /navsat/fix/status/parameter_updates /navsat/fix/velocity/parameter_descriptions /navsat/fix/velocity/parameter_updates /navsat/vel /odometry/filtered /public/robot/cmd_vel /public/robot/initialpose /public/robot/map /public/robot/map_metadata /public/robot/move_base/cancel /public/robot/move_base/feedback /public/robot/move_base/goal /public/robot/move_base/result /public/robot/move_base/status /public/robot/move_base_simple/goal /public/robot/odometry/filtered /public/robot/twist_marker_server/feedback /public/robot/twist_marker_server/update /public/robot/twist_marker_server/update_full /public/tf /public/tf_static /rosout /rosout_agg /scan /set_pose /tf /tf_static /twist_marker_server/cmd_vel /twist_marker_server/feedback /twist_marker_server/update /twist_marker_server/update_full

3. 通过终端发送一个速度指令给机器人rostopic pub [TOPIC]（对应第一课13页）。

$ rostopic pub -r 10 /cmd_vel geometry_msgs/Twist "linear: x: 0.8 y: 0.0 z: 0.0

angular: x: 0.0 y: 0.0 z: 0.6"

4. 编写代码使用键盘或者手柄遥控机器人运动（对应第一课22-26页）。

$ rosrun teleop_twist_keyboard teleop_twist_keyboard.py

5. 新建launch文件使用robotcup环境，并且使用键盘控制机器人运动。

$ roslaunch husky_gazebo husky_robocup14.launch

<?xml version="1.0"?>
<!--
-->
<launch>

  <arg name="world_name" default="/usr/share/gazebo-7/worlds/robocup14_spl_field.world"/>

  <arg name="laser_enabled" default="true"/>
  <arg name="kinect_enabled" default="false"/>

  <include file="$(find gazebo_ros)/launch/empty_world.launch">
    <arg name="world_name" value="$(arg world_name)"/> <!-- world_name is wrt GAZEBO_RESOURCE_PATH environment variable -->
    <arg name="paused" value="false"/>
    <arg name="use_sim_time" value="true"/>
    <arg name="gui" value="true"/>
    <arg name="headless" value="false"/>
    <arg name="debug" value="false"/>
  </include>

  <include file="$(find husky_gazebo)/launch/spawn_husky.launch">
    <arg name="laser_enabled" value="$(arg laser_enabled)"/>
    <arg name="kinect_enabled" value="$(arg kinect_enabled)"/>
  </include>

  <node pkg="teleop_twist_keyboard" name="teleop_husky" type="teleop_twist_keyboard.py"/>

</launch>

评分标准和提示，参考英文原文。

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附录：习题原文

Exercise Session 1

Theory

-       ROS architecture

-       ROS master, nodes, and topics

-       Console commands

-       Catkin workspace and build system

-       Launch-files

Exercise

Get to knowROS by inspecting the simulation of a Husky robot.

1.    Setup the Husky simulation:http://wiki.ros.org/husky_gazebo/Tutorials/Simulating%20HuskyRemember, our pre-installed ROS distro version (<distro>) is kinetic.

2.    Launch the simulation and inspect the created nodes and their topicsusing (Lecture 1 Slides 11/12):

rosnode list rostopic list

rostopic echo [TOPIC] rostopic hz [TOPIC] rqt_graph

For more information take a look at the slides or: http://wiki.ros.org/rostopichttp://wiki.ros.org/rosnode

3.    Command a desired velocity to the robot from the terminal (rostopic pub [TOPIC]) (Lecture 1 Slide 13)

4.    Use teleop_twist_keyboard tocontrol your robot using the keyboard. Find it online and compile it fromsource! Use git clone to clone the repository to the folder

~/git. (Lecture 1 Slides 22-26)

For a short gitoverview see:

http://rogerdudler.github.io/git-guide/files/git_cheat_sheet.pdf

5.   Write a launch file with thefollowing content (Lecture 1 Slides 27-30):

-  husky simulation with a differentworld:

Include husky_empty_world.launchfile and change the world_name Argument, e.g. worlds/robocup14_spl_field.world aworld from the directory /usr/share/gazebo-7/worlds.

Note: theworld_name is with respect to /usr/share/gazebo-7/

-  teleop_twist_keyboard node

Evaluation

❏    Check if teleop_twist_keyboardis compiled from source (roscd teleop_twist_keyboard should show the catkin_ws folder)                                                                      [40%]

❏    Start the launch file. Thisshould bring everything up that’s needed to drive Husky with the keyboard asshown in the above image.                                                                                  [60%]

Hints

●     If the robot stops again after sending the velocity command, specifythe rate of the publisher. Check out rostopic pub --help.

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