ROS command line tool

rostopic

1. List all current topics ：

rostopic list

give the result as follows ：

/rosout
/rosout_agg
/turtle1/cmd_vel
/turtle1/color_sensor
/turtle1/pose

2. Post messages from the keyboard ：
topic of conversation data structure Specific data

 rostopic pub /turtle1/cmd_vel geometry_msgs/Twist "linear:
  x: 0.0
  y: 0.0
  z: 0.0
angular:
  x: 0.0
  y: 0.0
  z: 0.0"

Line speed reading ： rice / second
angular velocity ： radian / second

We change the line speed reading to 1：

We found the turtle moving forward , It stopped after a short distance , This is because it is only released once , Not always released .
Next, we try to publish ten times a second ：

rostopic pub -r 10 /turtle1/cmd_vel geometry_msgs/Twist "linear:
  x: 1.0
  y: 0.0
  z: 0.0
angular:
  x: 0.0
  y: 0.0
  z: 0.0"

We found the turtle walking straight ahead , Don't stop when you hit the wall , Can press ctrl+c stop it ：


By releasing linear velocity and angular velocity at the same time , We can draw circles ：

rostopic pub -r 10 /turtle1/cmd_vel geometry_msgs/Twi "linear:
  x: 1.0
  y: 0.0
  z: 0.0
angular:
  x: 0.0
  y: 0.0
  z: 1.0"

rosservice

List all services ：

rosservice list

The following services can be called ：

/clear
/kill
/reset
/rosout/get_loggers
/rosout/set_logger_level
/spawn
/teleop_turtle/get_loggers
/teleop_turtle/set_logger_level
/turtle1/set_pen
/turtle1/teleport_absolute
/turtle1/teleport_relative
/turtlesim/get_loggers
/turtlesim/set_logger_level

Call the service to generate a new turtle ：

rosservice call /spawn "x: 2.0
y: 2.0
theta: 0.0
name: 'turtle2'"

Be careful ： The lower left corner of the simulator is the coordinate origin , there xy Indicates the location where the new Turtle was born .

rosbag

Mainly used to record data , Data can be reproduced .
Suppose we want to debug the UAV , Then there is no need to fly the UAV every time for debugging , The flight data of the aircraft can be recorded , Then it can be debugged in the Laboratory .
Save the turtle's current movement data in a package ：

rosbag record -a -o rec

After the record is finished , The recorded data will be placed in the current terminal directory .
Duplicate data ：

rosbag play rec_2022-02-13-11-54-34.bag