roscore<\/code>, launch the turtlesim node.<\/p>\n$ rosrun turtlesim turtlesim_node<\/pre>\nLaunch the teleop node so you can control the turtle on the screen with your keyboard.<\/p>\n
$ rosrun turtlesim turtle_teleop_key<\/pre>\nAnd now, let\u2019s see which topic data we can use.<\/p>\n
$ rostopic\u00a0 list\r\n\/rosout\r\n\/rosout_agg\r\n\/turtle1\/cmd_vel\r\n\/turtle1\/color_sensor\r\n\/turtle1\/pose<\/pre>\nThe \/turtle1\/pose topic contains information about the current turtle pose in the workspace. What data can we use from there? Let\u2019s find out.<\/p>\n
$ rostopic info \/turtle1\/pose\r\nType: turtlesim\/Pose\r\n\r\nPublishers:\r\n\u00a0* \/turtlesim (http:\/\/ed-pc:37099\/)\r\n\r\nSubscribers: None<\/pre>\n$ rosmsg show turtlesim\/Pose\r\nfloat32 x\r\nfloat32 y\r\nfloat32 theta\r\nfloat32 linear_velocity\r\nfloat32 angular_velocity<\/pre>\nOK, it seems that we could monitor any of those fields, as they\u2019re all numbers. Let\u2019s monitor the x position of the turtle.<\/p>\n
$ rqt_plot \/turtle1\/pose\/x<\/pre>\n![\"rqt_plot](\"https:\/\/roboticsbackend.com\/wp-content\/uploads\/2019\/07\/rqt_plot_turtlesim-1024x478.png\")
<\/p>\n
If you want to monitor other topics through rqt_plot, just add them from the input text box. Remember to always precise which field you\u2019re monitoring. If you just type \u201cturtle1\/pose\u201d, rqt_plot won\u2019t know which field you want to plot. In this case it might create a plot for each of the 5 available fields on the topic (x, y, theta, linear velocity, and angular velocity)<\/p>\n