basic informations about ros_turtlesim rostopic pub -r 5 /turtle1/cmd_vel geometry_msgs/Twist '{linear: {x: 0.1, y: 0.0, z: 0.0}, angular: {x: 0.0, y: 0.0, z: 0.0}}' rosrun turtlesim turtlesim_node rosrun turtlesim turtle_teleop_key What is the first command you must run in ROS? roscore What is the command to run the Turtlesim simulator? rosrun turtlesim turtlesim_node What is the command to find the list of all ROS nodes? rosnode list What is the command to find the list of all ROS topics? rostopic list What is the topic that tells about the position of the turtle? /turtle1/pose What is the topic that sends command to the turtle to make it move? turtle1/cmd_vel What is the command that tells you information about the topic about velocity? rostopic info /turtle1/cmd_vel What is the node used to publish velocity commands to the turtle? turtle_teleop_key What is the node used to subscribe to velocity commands to the turtle? turtlesim What is the command that allows to see the type of message for velocity topic? rostopic info /turtle1/cmd_vel What is the content of the velocity message? Explain its content. rosmsg show geometry_msgs/Twist
geometry_msgs/Vector3 linear
float64 x
float64 y
float64 z
geometry_msgs/Vector3 angular
float64 x
float64 y
float64 z
we use x y for linear velocity and z for angular velocity What is the content of the position message? Explain its content rosmsg show turtlesim/Pose
float32 x
float32 y
float32 theta
float32 linear_velocity
float32 angular_velocity rosservice list rosservice info /spawn rossrv info turtlesim/Spawn rosservice call /spawn 7 0 0 turtle2 //for create another turtle rosservice call /kill turtle2 //for kill the turtle