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2020-04-26 06:47:25 -0500 marked best answer How to tag a question on this site (properly)?

Multiple robots in ROS Gazebo SITL with separate MAVlink/MAVproxy software codes is the original question which isn't having proper tags; Commas are not accepted while tagging and re-tagging apparently requires 100 to 500 Karma points; Unfortunately, I was able to tag just one tag and all other tags require "number, characters or -+.#" (something that I have been unable to understand).

I have spent about an hour on this and I would like to set the tags for the question as "gazebo .ros mav quadcopter .launch .world mavconn SITL roslaunch multi-agent". Can you please let me know if that is possible? (What am I doing wrong while tagging?)

Thanks for your time and consideration.

Prasad N R

Appended information: Trying "1gazebo 2.ros 3mav 4quadcopter 5.launch 6.world 7mavconn 8SITL 9roslaunch 10multiagent" resulted in '1gazebo', '2.ros', '3mav', '4quadcopter', '5.launch', '6.world', '7mavconn', '8SITL', '9roslaunch' and '10multi-agent' tags (with numbers). Trying commas with spaces like "gazebo, .ros, mav, quadcopter, .launch, .world, mavconn, SITL, roslaunch, multi-agent" didn't work out either. Other similar attempts like "gazebo -+.# .ros -+.# mav -+.# quadcopter -+.# .launch -+.# .world -+.# mavconn -+.# SITL -+.# roslaunch -+.# multi-agent" didn't work out.

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2017-01-26 01:12:29 -0500 commented answer ROSWTF "unexpectedly connected" message and creation of new nodes

+1 "you are not visualizing new topics but new edges in the graph"

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2017-01-22 12:35:39 -0500 commented question Simulation and actuation of custom model in ROS Gazebo

@tfoote , Thanks for closing this article (I am sorry; I didn't find any other site to explain this). Yes, But, I would like to see some solution nevertheless. (Either by myself or by any other person; Many people would be helped I believe) Thanks for your active participation @tfoote .

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2016-12-21 05:27:12 -0500 commented answer Problem with the robot model collapsing

@emersonfs , Can you explain how you 'disabled' PID? It can be done by software or parameters can be set. (One of the most popular methods is to set I and D to 0 and controlling gain and offset with P. That will enhance the quality of answer by a lot.)

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2016-12-21 05:08:52 -0500 answered a question Gazebo: robot oscillates after spawn

I am not sure if this is the proper answer; But, I am unsure if it is because of the sequence of connection; Spawning model and then connecting or opening the socket and then spawning. For me, this is happening when I spawn the second robot.

https://vimeo.com/194174316 https://vimeo.com/192273295

The same model when spawned for the first time works properly; I believe that the issue is because of connection. I hope this helps someone (including me) greatly if this answer is suitably edited and posted.

2016-12-18 12:03:44 -0500 commented question Gazebo Tutorials for creating a plugin?

@hsu I have a question here: http://answers.ros.org/question/25018... and I need custom plugin to actuate joints. I have seen some; But, I am having a hard time understanding function calls. Thanks for time and consideration.

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2016-12-16 06:01:14 -0500 asked a question Simulation and actuation of custom model in ROS Gazebo

Can you be requested to let me know how I can build a software robot from scratch and simulate in ROS Gazebo (without any pre-existing package)? I am trying to extend Erle Robotics Tutorials' simulation to multi-drone simulation and that is causing a lot of issues including some strange issues with software-tools like roswtf.

So, in an attempt to reduce the problem statement to bare-minimum, I have decided to simulate three links and two joints which represent human-hand. I can create three 3D models (using Blender). One will be one 'thin' cylinder with a base plate attached and other two will be 'thin cylinders'. I can then link STL using URDF file as mentioned in this tutorial. But, what I am failing to understand is how I can actuate the joints using C++ code.

Optionally, it will be great if you can let me know how I can extend C++ code with custom wrappers for Python/how I can create command-line ROS service called through relatively minimal YAML file to actuate two joints (I can call system functions through some script/code).

I badly need a solution for this and any help will be greatly and whole-heartedly appreciated. Thanks for your time and consideration.

Humble note: I have read tutorials on XML and URDF Tutorials. I read URDF Controller Example and I did not understand data-type of "wheel1_state" variable and why I should use pr2 packages (I would like to see custom package) and other tutorials like robot_state_publisher do not describe the actuation of joints.

2016-12-16 04:55:48 -0500 commented answer How to import stl files into urdf files

+1 But, I would still like to know how a model created in Catia/Blender (say a simple two joint three link structure hand equivalent) can be simulated in ROS Gazebo interface through C++ code (from scratch).

2016-12-06 01:26:06 -0500 asked a question ROSWTF "unexpectedly connected" message and creation of new nodes

I am attempting multi-robot simulation (currently involving two robots) and the problem is with the roswtf which throws "WARNING The following nodes are unexpectedly connected:" warning as mentioned in this terse and beautiful question (But the answer is not satisfactory). But, in my case, roswtf is also creating /tf topics and creating new nodes like /roswtf_11591_1480848778816 and /roswtf_11751_1480848797413 each time I run roswtf.

The rqt_graph s are as shown.

and

Can somebody be requested to let me know why this is happening and the reason behind it? Thanks for your time and consideration.

Reference note: The entire log can be found here.

2016-11-13 10:12:59 -0500 commented question Launching multiple instances of same ROS node (with different names)

@vooon , Hats off and thanks for your efforts; almost like "God of software", you solved it. This is the proper answer; So amazing. I solved this with (no private parameter needed) "/mavros_copter/..." which isn't filesystem that I was searching for in "/home" and "/usr" and compiled.

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2016-11-11 14:53:06 -0500 commented answer Launching multiple instances of same ROS node (with different names)

Fixed that typo :) @ahendrix I think we both are close to the solution. You are humbly requested to let me know. Thanks! (video has been made as mentioned in question https://vimeo.com/191208613 ) roslaunch both copter and rover in one launch has flaws as mentioned in reference question. (no chars)

2016-11-11 09:46:17 -0500 commented question Launching multiple instances of same ROS node (with different names)

The output of rosnode info is too cryptic to understand and SearchMonkey returns nothing when I search for "mavros" in files (except mavros_node.cpp). I am ready to help with documentation on mavros once this research is finished. (I really wish to finish this soon and hope to contribute more)

2016-11-11 09:41:21 -0500 commented question Launching multiple instances of same ROS node (with different names)

@vooon and viewers, you are humbly requested to let me know the mistake; "mavros_copter" node ( = "mavros" ) doesn't work like "mavros" (with __name:= override or directly using in launch file) What files that I should modify?

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2016-11-11 03:31:10 -0500 commented question Launching multiple instances of same ROS node (with different names)

@vooon , Thanks for that excellent clarification; If you find difficulty, I will upload on Github (multiple git init required) Trying __name and rosnode ; Thank you so much and I consider this an opportunity to thank you for excellent contributions to robotic softwares.

2016-11-11 03:20:58 -0500 edited question Launching multiple instances of same ROS node (with different names)

The problem is in simulating two independent different robots in Gazebo: Copter and Rover with same mavros functionality. (Two independent instances of mavros would do great) Can two instances of mavros nodes be run using different names?

So, I tried to call mavros and the problem turned out to be "A new node registered with same name" which terminates Gazebo. To avoid this problem, I have tried to rename node-calls and the attempts include the following mentioned below.

<node ns="copter" pkg="mavros" type="mavros_node" name="mavros">
<node ns="rover" pkg="mavros" type="mavros_node" name="mavros">

1. Using namespaces as shown above; This still registers the node name as "/mavros" instead of "/copter/mavros" and "/rover/mavros"

2. Coding separate mavros_node codes for copter and rover instead of mavros_node.cpp. The modified version contains the lines shown below.

ros::init(argc, argv, "mavros_copter"); //In mavros_node_copter.cpp

ros::init(argc, argv, "mavros_rover"); //In mavros_node_rover.cpp

mavros_node.cpp, mavros_node_copter.cpp and mavros_node_rover.cpp source files are all placed in the same original folder. The entire package is then compiled with catkin_make. But, even then, using "mavros_copter" and "mavros_rover" as node name won't work with ROS Service properly while using "mavros" works.

<node pkg="mavros" type="mavros_node" name="mavros"> is the original code in launch file which works.

type="mavros_node_copter" name="mavros" (works)

type="mavros_node_copter" name="mavros_copter" (doesn't work)

3. I tried rqt_graph and this is the most confusing part in the software simulation. mavros node is shown as an independent node. I tried to assess how mavros is interacting with Gazebo and where how that is getting called and rqt_graph doesn't provide that information (even for original code which works).

4. Remapping nodes is not possible using roslaunch while command-line options like rosrun can be used. I even tried _name:="something" in command line along with roslaunch; But, that does not seem to work. (Original name is retained somehow)

Can you please let me know how multiple instances of same node can be run? (Optional: It will be great if you let me know how mavros is interacting with Gazebo)

Any help will be greatly, gratefully and whole-heartedly appreciated. Thanks for your time and consideration.

Prasad N R

Reference question: Multiple robots in ROS Gazebo SITL with separate MAVlink/MAVproxy codes

copter_circuit -> apm_sitl_copter & copter_circuit.world -> node_copter

rover_circuit1 -> apm_sitl_rover & rover_circuit1.world (.so plugin) -> node_rover

Output of roswtf , launch commands , CMakeLists.txt and the original folder structure can be found in Google Drive (uploaded sometime ago).

Can you please let me know if I should create new packages? (namely mavros_copter and mavros_rover and guidance on that will be gratefully appreciated)

A relatively small video has been made regarding the same.