rostopic

rostopic command line tool은 ROS 항목에 대한 정보를 표시
현재 active 된 topic list와 특정한 publisher 및 subscribers,
publish 된 topic의 대역폭(bandwidth)와 topic에 publish 된 message를 표시할 수 있음

메시지의 표시는 plotting-friendly format으로 출력되도록 구성됨

rostopic은 다른 여러 ROS 도구와 마찬가지로 메시지의 내용을 나타내기 위해
command line에 YAML 구문을 사용한다.

rostopic pub과 같은 명령에 이 YAML 구문을 사용하는 방법에 대한 자세한 내용은
YAML Command line 가이드를 참조해야 한다.
--

rostopic bw: 항목에서 사용한 대역폭 표시(bandwidth)
rostopic delay: 헤더가 있는 항목에 대한 delay 표시
rostopic echo: message를 화면으로 출력
rostopic find: topic의 type 찾기
rostopic hz: topic의 publishing rate 표시
rostopic info: active topic에 대한 information 출력
rostopic list: active topic에 대한 information list 출력
rostopic pub: publish dat to topic
rostopic type: topic type 출력

rostopic: 
> bw
report된 bandwith는 수신된 bandwidth임.
네트워크 연결 문제가 있거나 rostopic이 Publisher를 따라가지 못할 경우
report된 숫자가 실제 bandwidth보다 낮을 수 있음

==

$ roscore

$ rosrun turtlesim turtlesim_node

$ rosrun turtlesim turtle_teleop_key

---
$ rostopic
bw echo find hz info list pub type

$ rostopic list
/rosout
/rosout_agg
/turtle1/cmd_vel
/turtle1/color_sensor
/turtle1/pose

--

$ rostopic type /turtle1/cmd_vel
geometry_msgs/Twist

$ rostopic info /turtle1/cmd_vel

Type: geometry_msgs/Twist

Publishers:
* /teleop_turtle (http://mnk-VirtualBox:35583/)

Subscribers:
* /turtlesim (http://mnk-VirtualBox:35583/)
* rostopic...

===
/opt/ros/noetic/share/turtlesim/msg (Color.msg, Pose.msg)
Pose.msg

float32 x
float32 y
float32 theta

float32 linear_velocity
float32 angular_velocity

===

mkdir msg

cd msg

vim Move.msg
--
float32 x
float32 y
float32 theta

float32 linear_velocity
float32 angular_velocity
--