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Cannot roslaunch motors.launch #6
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Update: After changing my .launch files i got motors.launch running, but
started roslaunch server http://ev3dev:44509/ SUMMARYPARAMETERS
NODES ROS_MASTER_URI=http://johnny-ThinkPad-E560.local:11311 core service [/rosout] found Would appreciate any help, so i can get my motors running, i can also provide more info if you need them. Thank you for your help! |
I also saw the closed topic, that you have to run motors.launch on your EV3, so thats probably not the problem i have here... |
you should probably not use roslaunch on the ev3 - its python and takes lot of resources.... If not, you probably have to setup ROS IP |
So what program do i have to launch on which computer? Because in Issue #2 you told to launch motors.launch on the ev3. Im quite confused and would like a short step by step guide. Thank you for your help! |
Nope I said he should execute the ev3_manager there. It is also said in my Getting Started: Actually you need to launch two things, after setup:
And If it is not working like that: it could be, that you have no connection from EV3 to your PC. Because ROS requires a DNS to work normally. If you do not have a DNS in your system - which makes it possible to do for example ssh root@ev3dev instead of ssh root@192.168.0.23 - then you need ROS ip. And then you set the ROS master URI to something like http://IP_OF_YOUR_PC:11311 and use the rosip command to set the rosip on the brick and you also need to export it on your pc like export ROS_IP="IP_OF_YOUR_PC". See also (it is basic ros stuff): |
Thanks for your help, its working fine for me now! Just one last question: What do i have to do to control the EV3 with my remote controller? Is there already a programm for that problem, or do i have to write it on my own? I also wanna control my EV3 like you in your Youtube-Video :) And again, thanks for your help! |
👍 Nice, you are welcome ;-) Well you need a joy node connected to a node which translates the joystick to speed around z and along x axis and outputs a topic mostly called /cmd_vel (geometry_msgs/Twist) and to launch a dual drive controller using two joints on the EV3. |
After a little break, i'm trying to get my robot running again, the teleop node is running fine, but i have no idea, how i have to use the /cmd_vel topics now to get my robot working. I never worked with ros_control, so i'm very grateful for your help! |
Does it publish messages to the right topic? Do you receive the messages on your EV3? |
i can echo the /cmd_vel topic on my EV3, so no problem there. What i don't understand is, what i have to do after that to have my motors running. You said, i need a diff_drive controller to use the topics, but what type of controller is working, when i start ev3_manager on my EV3. What type of messages to i have to publish to get it working? |
Well the thing is you need to create launchfiles which load the motors. Those launchfiles are executed on your PC. They advice the ros control manager in the ev3_manager to load shard libraries. You supply arguments to it by the yaml setting file or parameters in the launchfile. Those parameters define, what controller is loaded and which topics the controller uses. So if you load controllers the ev3_manager node will spawn publishers and subscribers depending on the controller. Just saw there is also an issue with the examples, but this should do:
motors.yaml is in h4r_ev3_launch. You can copy it to yours and change the name in the rosparam line Motors are set to be connected to Port C and D there. |
Hello,
for a project at my university i'm trying to get ROS running on EV3. After some problems i got Yocto booted on the roboter and a wifi connection with my laptop. But now i have the problem, that i cannot roslaunch motors. launch; here is the terminal code:
johnny@johnny-ThinkPad-E560:~/catkin_ws/src/h4r_ev3_ctrl/h4r_ev3_launch/launch$ roslaunch motors.launch
... logging to /home/johnny/.ros/log/5b624bf0-7a76-11e6-9a47-dc5360e3e6c1/roslaunch-johnny-ThinkPad-E560-11331.log
Checking log directory for disk usage. This may take awhile.
Press Ctrl-C to interrupt
Done checking log file disk usage. Usage is <1GB.
[motors.launch] requires the 'ev3_hostname' arg to be set
The traceback for the exception was written to the log file
i also tried to set the hostname manually in the .launch but then he cannot find the ressource h4r_ev3_launch
I would really appreciate a little guide so i can also control the EV3 with my Remote Controller (like in your Youtube Video).
Thank you for your help!
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