This would have been one of the best channels on RU-vid for learning Robotics and ROS programming ? Why did you stop? You're tutorials,explanations and core concept clarity are remarkable. Please post more such amazing content.
I love practical tutorials. It is hard to only learn from simulations and codes and the stuff without real hardware, robot control! Thank you so much and keep up the good job! You could talk to the guy from Hash Robotics, he is learning and teaching ROS now and he has a humanoid robot awesome project, you could help him boost up his ROS learning!
This was the video and page that really made me understand ROS control and got me past the point of implementing the hardware interface! Thank you very much, could you do an updated version for ROS 2?
Dude why did you stop posting videos?:( these are so amazing, pls continue making them, they're damn helpful, thanks for explaining ros like no one has :D
Arduino uno is not working good at higher rates to receive command(subscribe), execute(pwm) it and send feedback (via service server). For 100hz may be u can use different mcu which can handle the load.
Robotics and ROS Learning Yes, I have had that problem as well when nh.spinOnce() is in the main loop. I found that putting it inside a timer helps a lot. With this method, I am able to publish and subscribe at 100 hz #define ROS_MESSAGE_CHECK 10000 // 0.01 seconds elapsedMicros rosMessageCheck; Void loop(){ if (rosMessageCheck >ROS_MESSAGE_CHECK) { nh.spinOnce(); rosMessageCheck = 0; } }
For my final year project I am using a dc motor with an encoder as the actuator in a custom made, 3d printed 6-axis robotic arm which does a pick and place operation. Can u suggest me some tutorials or help me out with how to implement kinematics for the pick and place operation and also implementing pid to the actuators.
I am trying to learn more about ROS and come across this interesting tutorial. I am replicating what you did in your video/project shared here. But when I send a command for position control in rad the motor doesn't move. I have been working to resolve the problem for the last 10 days but I haven't been successful. Could you please help?
hi.. Thanks for your video. I am having issue with mine. My effort commands are always 0.(in write method) no pwm generation. I tried with hard coded pub array. Still no pwm output. Kindly help
Very good job, but I have one question: In case I am using stepper motor withoud encoder, so I have an open loop. How should I change a hardware interface file and what should I do in that case?
Thank you. For stepper motors you can use position_controllers/JointPositionController. You can check my blog to understand how to write a hardware interface file and more about ROS control. www.rosroboticslearning.com/ros-control If you still have a question please don't hesitate to ask. Thanks again.
I do not understand that the formula of "(360.0*1000*(encoderPos-last_pos)) /(2200.0*(now - lastTime))" is in degrees/s, right? (While T = 500ms, And ROS is rad/s). Looking forward to hearing from you soon. Thanks
im getting error, please help me ERROR: cannot launch node of type [ros_control_example/single_joint_hardware_interface]: Cannot locate node of type [single_joint_hardware_interface] in package [ros_control_example]
Hi.. Thank for your video. I have got a problem when I launched check_urdf.launch or check_position_controller.launch. In Rviz, error Fixed Frame and RobotModel existed. Can you help me?
Robotics and ROS Learning when i run check_velocity_controller.launch, value PWM Cmd increases from 0 to 255, i don’t change your arduino code. Do you know what ‘s erorr?
I have a question about the member function read(), which belongs to the ROBOTHardwareInterface class. We know that we are receiving the position and velocity of the joint from the server using service communication. What is the advantage of using service communication here? Is it possible to replace this with topic communication?
Service is a request-reply type communication Where as topic is a broadcast-listen type communication. In hardware interface node, we want the values from the hardware only when we want (i.e., calling read() method). If you use topic here instead of service-client then your subscriber in hardware interface node will be called when ever the hardware publishes data but not when hardware interface node needs. Anyways this was my way of implementation. You can implement in your own way either using topics or i2c or any other protocol. Hope this answers your question. Regards, Sai Krishna
@@roboticsandroslearning8232 I see that the read() function uses the "Service & Client" communication protocol to get the real-time value of the joint. That's very clear. Thanks for that. Thank you very much for your kindness.
This's an absolutely helpful tutorial for someone who's new to ROS, just like me. I was trying to practice it in my own laptop. However, t和following error came up while I catkin_make the workspace. Wondering if anyone got the same problem before? Not sure how to fix this issue :-( Any advice would be appreciated! -- Could not find the required component 'three_dof_planar_manipulator'. The following CMake error indicates that you either need to install the package with the same name or change your environment so that it can be found. CMake Error at /opt/ros/kinetic/share/catkin/cmake/catkinConfig.cmake:83 (find_package): Could not find a package configuration file provided by "three_dof_planar_manipulator" with any of the following names: three_dof_planar_manipulatorConfig.cmake three_dof_planar_manipulator-config.cmake Thank you!
@@roboticsandroslearning8232 Wow! Thank you very much for helping me out. I tried to build this "three_dof_planar_manipulator" as you shared. It seems can't find "Floats_array.h", I wonder if this require me to edit the CMakeList? [ 11%] Building CXX object three_dof_planar_manipulator/CMakeFiles/robot_hardware_interface.dir/src/robot_hardware_interface_node.cpp.o In file included from /home/caris/three_dof_planar_manipulator/src/three_dof_planar_manipulator/src/robot_hardware_interface_node.cpp:1:0: /home/caris/three_dof_planar_manipulator/src/three_dof_planar_manipulator/include/three_dof_planar_manipulator/robot_hardware_interface.h:12:55: fatal error: three_dof_planar_manipulator/Floats_array.h: No such file or directory compilation terminated. three_dof_planar_manipulator/CMakeFiles/robot_hardware_interface.dir/build.make:62: recipe for target 'three_dof_planar_manipulator/CMakeFiles/robot_hardware_interface.dir/src/robot_hardware_interface_node.cpp.o' failed make[2]: *** [three_dof_planar_manipulator/CMakeFiles/robot_hardware_interface.dir/src/robot_hardware_interface_node.cpp.o] Error 1 CMakeFiles/Makefile2:481: recipe for target 'three_dof_planar_manipulator/CMakeFiles/robot_hardware_interface.dir/all' failed make[1]: *** [three_dof_planar_manipulator/CMakeFiles/robot_hardware_interface.dir/all] Error 2 Makefile:138: recipe for target 'all' failed make: *** [all] Error 2 Invoking "make -j1 -l1" failed Again, thank you for your time!
Floats_array.h is a custom service I have created in three_dof_planar_manipulator package. It should not give error. I made this package in ROS kinetic. May I know whoch version of ROS you are building it in.
And if you want to work with ros_control package only, then you can delete three_dof_planar_manipulator package from your worksapce (if you are not able to resolve above error) and edit package.xml file of ros_control package to remove dependency of three_dof_planar_manipulator package. github.com/bandasaikrishna/ros_control_example/blob/master/ros_control_example/package.xml I cannot remember the reason why I have added this dependency :). Regards Sai krishna.
@@roboticsandroslearning8232 Hello Sai, Thank you for your time and suggestion. I'm using kinetic+ubuntu 16.04, and that error came out when I catkin_make the workspace where both three_dof_planar_manipulator and ros_control packages in my src file. It's weird that the same error still occurs after removing the three_dof_planar_manipulator dependencies in package.xml file. I was searching online, someone has the similar problem said maybe edit CmakeList and add that three_planar_manipulator dependency would work. I'm still trying to figure that out at same time. github.com/stereolabs/zed-ros-wrapper/issues/262 Best, Dylan
