The ROS Transform System (TF) | Getting Ready to Build Robots with ROS #6

[@bharath-rao]

We really needed a good ROS tutorial for beginners - like this one. This is great. Please keep this going. Good luck!

[@ArticulatedRobotics]

Thanks, I appreciate it!

[@dinoboy1810]

Thank you , This is really informative

[@ArticulatedRobotics]

Thanks!

[@emthefruitygem]

I'm currently sweating my way through my senior project for my engineering degree, and good god are these tutorials a blessing. Thank you for everything you do, even if you are Australian

[@harrytraskos5964]

Yeah, this is when you choose ROS...

[@underwaterdol613]

Articulated Robotics makes the best ROS2 tutorials in the internet. Thank you very much and I am looking forward for more videos in ROS2. Keep the awesome work!

[@k_ros849]

Great vid!! At 13:17 there I got an error tho: "No executable found" The fix is to type "ros2 run tf2_tools view_frames" instead. So no ".py" at the end. Worked for me at least

[@ArticulatedRobotics]

Thanks! Yeah I think they've changed that behaviour in the time since. However they have also since released rqt_tf_tree which is a much easier way to achieve the same result so I recommend using that instead!

[@PranavAthreya]

Josh, I cannot thank you enough for teaching me these fundamentals concepts of ROS. I hope you continue to put out such quality content so that I can keep growing as a roboticist! I'd be happy to pay for your Patreon channel! Even if you are Australian!

[@Adroitbit]

At 11:07 I get this error terminate called after throwing an instance of 'ros::InvalidNameException' what(): Character [

[@quangnhatle2512]

I came across your channel and this is by far the best ROS channel. Keep up the good work! Your style is very concise, get to the point and unique. Very potential in the future. I hope that you will have 200-300K subs in the near future.

[@ArticulatedRobotics]

Thank you!

[@nihongoapprentice8193]

By the way folks, if you watching this on 23/07/23. Which is using Humble ROS. Here some typos updated that might come in handy. # sudo apt intall ros-humble-xacro ros-humble-joint-state-publisher-gui # sudo apt intall ros-humble-joint-state-publisher-gui Also here it is the command to run the URDF file, I had a typo and struggled a bit. I put the file in the home/user/ folder as it promts its not found in terminal and then enter the command.. # ros2 run robot_state_publisher robot_state_publisher --ros-args -p robot_description:="$( xacro ~/example_robot.urdf.xacro )"

[@ArticulatedRobotics]

Thank you!

[@FaizanAhmadKhan-v5f]

I have recheched properly no typoss, Still getting the same error. Can you help please.

[@gesucristo0]

I keep getting the same error. How did you solve? Did you just put the file in the folder suggested ?

[@Palies-fu8hd]

Great Series!! , if you can create more content about setting up and exporting URDF from various 3D CAD SW , will be amazing the web is very unclear about that.

[@manishnayak1000]

Is Xacro necessary to pass as an input to robot_state_publisher parameters? Can't we pass the URDF Directly, if it's already available? I was trying to run the node directly in CLI without using launch file but was unable to do. Then I added the "xacro xmlns ..." line manually in the URDF, treated it like a xacro and it worked. But this seems roundabout. I believe this has to do with the point that the node expects not the path, but rather the entire content.

[@anbepueanbepue4517]

Really well explained! Thanks, and looking forward to more videos!

[@ArticulatedRobotics]

Thanks, I'm glad you liked it!

[@ottachchigepiyaranga8564]

Hi Josh, I have a question and really appreciate your help. Can I use transmissions within URDF if I still publish joint states using the GUI ? For an example if I want to move joint B too when i publish states to joint A ? Thank you!

[@DevGhiya]

Hi, your way of explaining complex things in layman's terms is good. Currently I am in my way to complete my final year project where I needed to simulate my robot in ROS environment , would you provide me with some resources that i can go through for the same.

[@JonPeroutka]

this ROS2 series is infinitely better than a ROS2 course i paid for on Udemy. wish i found this one first!

[@ArticulatedRobotics]

Thanks Jon :)

[@alexnd98]

These videos are pure gold! Thanks for your work

[@ArticulatedRobotics]

Thank you very much :)

[@rotviepe]

I wished I've seen this video 2 years ago when I started learning ROS, it would had saved me a lot of trouble

[@TheRobotTest]

Great video. Great explanation. Helps a lot with getting into ros.

[@ArticulatedRobotics]

Thanks!

[@chocsise]

These are excellent. Running Humble on Ubuntu 22.04 Jammy and everything has gone quite well. But I’ve had trouble installing xacro and the joint-state-publisher-gui. Can anyone offer advice on how to do that?

[@chocsise]

Got it now. Had to sort out my public keys for downloading from repositories, run $> apt update and $> apt upgrade and then $> sudo apt install ros-humble-xacro and $> sudo apt install ros-humble-joint-state-publisher-gui

[@davidfarning8246]

Humble tester :) One of the best ros tranform videos available. Good job sticking the overall goal of transform which is knowing how diffent bodies relate to eachother in space. In some learning resources, It is too eash to get caugh up in the cool math or how cleverly TF works and lose the point of transforms.

[@ArticulatedRobotics]

Thanks :D

[@pai_not_bai]

Hi, I find this tutorial really helpful for me, but currently I need to run my program in ros noetic, and I have trouble running robot_state_publisher, is there command for ros1? Also may I know that if the urdf.xacro works same on both ros1 and ros2 environment?

[@ArticulatedRobotics]

Sorry it has been so long since I used ROS 1 I'm not sure. If I recall correctly, it's about the same except the URDF file is passed directly into RSP? Or something like that? I hope you got it working. The main parts of the URDF (joints, links, etc) work exactly the same on ROS1 and ROS2, but some things like plugins and some Gazebo settings will be different.

[@nekedem2795]

any update?

[@gesucristo0]

At @11:04, it appears that the file example_robot.urdf.xacro does not exist. Is it true? How should I create it? If not, where shall I find it?

[@christopherbousquet-jette4301]

same issues

[@lion87563]

If I have a map, and robot inside a map. If I want to get poses of the robot in the map frame, what do I need to write: 1. tf_echo map base_link 2. tf_echo base_link map These things confuses me, can someone explain to me please?

[@TotallyFriedChannel]

Informative and well designed vid!

[@ArticulatedRobotics]

Thanks!

[@WilliamStone-u7d]

Attempting to run robot_state_publisher I get : [ERROR] [1705783960.545567604] [rcl]: Failed to parse global arguments

[@WilliamStone-u7d]

googer somewhere said don't do that just pass the path to the udf file ros2 run robot_state_publisher robot_state_publisher src/urdf_example/description/example_robot.urdf.xacro That goes farther, but gripes about 10 errors. The first is the material "blue" isn't defined. so I copied the color section out of the include and pasted it the main file. Rerun and that error is cleared. That was easy enough but the next error is Unable to parse component [${arm_length/2}] to a double (while parsing a vector value) - yieks.... This mess ends with : Error: joint xml is not initialized correctly at line 233 in ./urdf_parser/src/model.cpp Failed to parse robot description using: urdf_xml_parser/URDFXMLParser terminate called after throwing an instance of 'std::runtime_error' what(): Unable to initialize urdf::model from robot description [ros2run]: Aborted

[@sawalikorde2722]

Hello actually I'm trying to control my robotic arm using rosserial, I'm using Arduino UNO and PCA 8695 but when I publish joint angles something happens and 0 joint angles are sent in between goal . can u pls help me

[@danielb.9137]

Hi, I have a question. I have a Robot with an existing urdf file. Now i want the last axis system to rotate 360 degree. Around the TCP like a screw driver. The last joint can turn about 320 deg in total. So the other Joints need to help. Is there a simple way to fix the axis through the TCP and let the robot rotate around it?

[@annamcfarlane9563]

great video

[@spxnr]

Awesome! Also- I think Caja is pronounced like “caha”

[@0jeetparmar0]

ros2 run robot_state_publisher robot_state_publisher --ros-args -p robot_description:="$(xacro path/to/my/xacro/file.urdf.xacro)" this does not work in my ros i am using ros2 humble how do i run this????

[@omeryldrm8038]

Using the language correctly is a base skill for teaching. And i searhed lot to find a refined knowledge for beginning. So far it seems great. Thanks for thee content. I am agreeing all the complements and adding this.

[@21area21]

Bro just started spitting fire out of nowhere! 4:48 🗣🔥🔥🔥

[@PranavAthreya]

Bro that was an insane catch!!!! He sounds really great!!

[@21area21]

​@@PranavAthreya😁 glad I wasn't alone. Haha

[@PranavAthreya]

@@21area21 i gotchu

[@earthrelated]

It works for me so super thank you bro!

[@buckcostanza3483]

great video, thanks!

[@markhannibal5434]

Thank you for the video

[@vikrantkalkal5943]

Hi , amazing video. You mentioned that it's painful to type commands for state_publisher and you gave a launch file for that. How do I use it? Should the launch file be put inside the launch folder , then edit the package.xml and colcon build after that?

[@vikrantkalkal5943]

I did what I typed above and it worked, now my question is , can we automate all that to just launch something and have our robot displayed in rviz?

[@nicobucher1711]

Insane Videoseries, i think i have never seen such a perfect series of tutorials. Videos are not too long, but include every important aspect. And its super good explained. Thank you so much for these Videos.

[@ArticulatedRobotics]

Thank you!

[@cangozpinar]

I really believe this is the best explanation out there. Also, love that you are using ROS2. Thanks a lot.

[@coolheis7469]

Amazing work! Thank u so much for the content! I have one question about robot_state_publisher command. How should i write this with noetic? If i try: rosrun robot_state_publisher robot_state_publisher --ros-args -p robot_description:="$( xacro ~/example_robot.urdf.xarco )" i get the following error: Valid characters are a-z, A-Z, / and in some cases ~. Aborted

[@henningfrestad1496]

Do you have any suggestions for how to build a telescopic boom in URDF(typically seen on lifts or cranes)?

[@henningfrestad1496]

And perhaps some tips on how to deal with hydraulic actuators. I struggle to find documentation on this.

[@jodydavis161]

Witch ROS to use

[@bukhaini]

Hi. Why in the tf tree the broadcaster shows "default authority?". I am using foxy and it shows the same too

[@ArticulatedRobotics]

You know, I have also wondered that and never looked into it... I just checked now, and the only source I can find is in the tf2 Python listener code. If I had to guess, it looks like they want to have a mechanism by which you can tell which node was broadcasting a particular transform, but that isn't implemented so it is overridden to just say "default_authority"? Someone in the know may be able to provide a better answer. In any case, it's nothing to worry about :) github.com/ros2/geometry2/blob/2687a3543bf61481b06dcf37839c7e92bed85d2e/tf2_ros_py/tf2_ros/transform_listener.py#L115-L123

[@LifeCodeGame]

Thanks a thousand for these great ROS videos. Helps me a lot to get back into robotics after having used ros1 back in the days :p

[@ArticulatedRobotics]

No worries, glad to help!

[@santos4027]

Great tutorials, keep it up!

[@cdband7642]

i tried to install ros-foxy-xarco but it kept telling "E:unable to locate packages" i already updated repository and followed intstructions in document before installing packages but not working .Is there any problem? Could you please help ?

[@tbtitans21]

Maybe you had humble version? On Ubuntu 22 its humble version so commands are: sudo apt install ros-humble-xacro ros-humble-joint-state-publisher-gui

[@cdband7642]

@@tbtitans21 i fixed the problem

[@earthrelated]

Thank you!

[@manigoyal4872]

Thank you 👍

[@TheRealFrankWizza]

So far, this has been the best guide to ROS/ROS2 I have followed. I am looking forward to whatever project lies ahead.

[@ArticulatedRobotics]

Thanks!

[@theoldboar6853]

Hello, so I tried following along with you for the dynamic transforms using robot_state_publisher and the URDF file but I keep getting errors: "module 'xml' has no attribute 'parsers' and 'ros2: error: unrecognized arguments: --ros-args -p Edit: Nvm I had a typo. Thanks for the video!

[@ArticulatedRobotics]

Thanks, I'm glad you got it sorted!

[@jirivchi]

@@ArticulatedRobotics thanks for your videos. I am getting error [rcl] : Failed to parse global arguments when I am trying Dynamic transformation system. Any advice? Thanks in advance

[@crisgulay]

@@jirivchi same problem

[@sharifshabani6616]

Your videos are very informative. Keep up the amazing work!

[@ArticulatedRobotics]

Thank you!

[@jacopojacopo648]

You're the best at explaining ros.thank you

[@ArticulatedRobotics]

Thanks!

[@davidortegaa]

Great video! best explanation ever found.

[@ArticulatedRobotics]

Thank you!

[@Anthonylion232]

Hi I just want to say that these videos have helped me so much in learning ROS2 for my uni project. I am on humble and I installed xacro and joint state publisher with the same code but just had humble instead of foxy. However when i run your code at 11:07 i get errors. Xacro.XacroException: No such file or directory ‘/home/user/example_robot.Urdu.xacro’ being one of the errors. It seems the error is just the fact that it cant fine the example_robot.Urdf file. Is there someway i can download this and then put in the directory?

[@Anthonylion232]

I needed up fixing the problem but I’m not sure as to why there was this problem in the first place. What i ended up doing was manually downloading the file example_robot_urdf.xacro and then placing it in my home folder and running he same code. But why did i have this problem in the first place. Why didn’t it get created automatically when i ran the same code you did? (I understand if you dont know why) Thanks for the videos!

[@crisgulay]

thank you for this @@Anthonylion232

[@FaizanAhmadKhan-v5f]

Hii, you found solution to this error? Please help.

[@chocsise]

How did you install xacro on Humble?

[@binayakghosh3770]

Great tutorial!

[@prasannakolar3833]

A very good, to the point tutorial... kudos!

[@ArticulatedRobotics]

Thanks!

[@Ducerobot]

😁👍

[@manalankm2882]

this is too good! thanks for your work : )

[@ArticulatedRobotics]

Thank you :)

[@viktorpavlov4499]

Thank you so much!

[@ArticulatedRobotics]

Thanks!

[@AndrewShtogrin]

I can’t start dynamic transforms cause I get „no such file or directory: ‚/home/…/example_robot.urdf.xacro‘

[@FaizanAhmadKhan-v5f]

hii, you found solution for this? please share