이론 : TF package의 이해

영어로 공부한 내용을 한국어로 번역하기가 더 헷갈린다. 그냥 영어로 정리하련다.

TF Package

TF package is the tranformation library for ROS. It supports transformation between frames, allowing user to find pose of any object in any frames.
Since there are framse for every joint on a robot transformation is required configure pose of the robot.

local position of the drink for robot’s head and left hand are different. So we need to make transform to configure global position.

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Nodes

I checked nodes based on turtlebot3_gazebo turtlebot3_house and turtlebot3_navigation turtlebot3_navigation.lauch gazebo simulation and navigation stack.

 

• view_frames : visualizes the full tree of coordinate transform -> you get a pdf file called frame.pdf with graphical image of current frames.

1. Modifying the package manually

modify line 89 of opt/ros/noetic/lib/tf/view_frames

m = r.search(vstr) #를
m = r.search(vstr.decode('utf-8')) #로 변경

then run

rosrun tf view_frames 

1. Install new tf2_tools package

sudo apt-get install ros-noetic-tf2-tools

then run

rosrun tf2_tools view_frames.py 

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• tf_monitor : monitors transforms between frames

rosrun tf tf_monitor

• tf_echo : prints specified transform to screen

rosrun tf tf_echo source_frame target_frame

• static_transform_publisher : command line tool for sending static transforms

static_transform_publisher x y z yaw pitch roll 
frame_id child_frame_id period_in_ms

Publish a static coordinate transform to tf using an x/y/z offset in meters and yaw/pitch/roll in radians

using in launch file looks like this

<launch>
<node pkg="tf" type="static_transform_publisher" name="map_nav_broadcaster" args="0 0 0 0 0 0 map nav 100"/>
</launch>