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2017-01-07 08:09:35 -0500 asked a question URDF generated by SW2URDF fails planning in MoveIt

I am using the sw_urdf_exporter plugin to generate a URDF file for my custom 5-dof robot. The plugin worked correctly and I was able to preview the URDF and even move the joints using the sample urdf_tutorials viewer. I generated a MoveIt config for the same, using the MoveIt setup assistant and I was able to load up the standard demo.launch file from the moveit config as well. RViz showed the robot prefectly.

The problem I faced was that I was not able to plan the trajectories reliably, I could only succesfully plan about 1-2 out of every 10 attempts. Even a few simple trajectories failed. I though this could be an issue with the KDL solver, but even IKfast, the alternate solver failed.(Check this question for details).

Now, just to ensure that there is no issue in my robot configuration, I built a URDF file by hand. I ensured that my joint configuration remained the same. This URDF worked flawlessly and almost all plans worked pretty fine. Even with the default KDL solver.

This tells me that there could have been an issue with the sw_urdf_exporter plugin. I am using solidworks 2013(the version recommended). My design is also pretty simple.

Has anybody got the plugin to generate a urdf which works reliably with MoveIt and planning? How can I debug what could have gone wrong in the URDF generation? I can provide both the generated and the handwritten URDFs if it would help someone.

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2017-01-06 13:56:21 -0500 answered a question Generating IK solution for use in MoveIT for 5 DOF arm

We have been trying to debug this issue since the past 2 days. With no clear reason for this problem, we decided to try solving the IK of robot of the same configuration with a simple URDF file. So we wrote a urdf by hand, with the same joint and link config as our robot. The URDF we used earlier was generated from our original CAD model using the Solidworks URDF Converter plugin.

With this simple URDF, we did the same process as mentioned above. From this new MoveIt config, the plans were working significantly better. With the earlier urdf, hardly 1 out of 10 plans would work and even simple plans where only 1 motor had to move were failing. But with this new URDF model, many plans are working realli good! Even with the basic KDL solver with OMPL. And this is the same 5 dof configuration we had before. Our guess is that the solidworks urdf exporter plugin, which is severely dated, might be causing the issues in the planning. But we are still figuring out the actual, fundamental cause for this issue.

As far as solving the above problem is concerned, building a URDF by hand solves this problem for us. Even the IKfast library generates an analytical cpp solution.

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2017-01-05 03:17:35 -0500 commented question Generating IK solution for use in MoveIT for 5 DOF arm

I installed Sympy 0.7.1, but i still get the same error with openrave. I've added the exact error in the above question...

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2017-01-04 15:13:41 -0500 asked a question Generating IK solution for use in MoveIT for 5 DOF arm

I am working on a custom 5 DOF arm(image at the bottom). I have generated the URDF, the MoveIt configs etc for it.

I want to have the basic IK, planning and collision detection features of MoveIt. Before programming my application, I tried running the simple planning in RViz, using the interactive marker etc. Now, since it is a 5 dof system, I had to enable "Allow Approximate IK solutions", for it to let me use the interactive markers. It was using OMPL by default. I tried planning for some random-valid goal states. The problem is that the planning success rate was very very low. 4 out of 5 times the planning failed. I also tried changing the planners from the dropdowns, but none of them were consistent in planning succesfully, all of them were failing quite frequently.

After looking up this problem here on Ros-Answers and many other places, we found that IKFast would be what we should use, as it works reliably for 5 dof systems.

After installing openrave and ikfast via source, we ran the commands to generate a IKfast cpp file(using this tutorial) for our robot model. We tried the TranslationDirection5D ik type. Now here we are getting a tuple index out of range error which is something that others have faced before and have not been able to solve. See this and this. Basically, we've now hit a wall trying to get the IK on my 5 dof robot to work properly. Openrave is not even able to generate an Ikfast cpp.

Here'ss the exact error i get when i try to generate an ikfast cpp,

Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/openravepy/_openravepy_/ikfast.py", line 9521, in <module>
    chaintree = solver.generateIkSolver(options.baselink,options.eelink,options.freeindices,solvefn=solvefn)
  File "/usr/local/lib/python2.7/dist-packages/openravepy/_openravepy_/ikfast.py", line 2281, in generateIkSolver
    chaintree = solvefn(self, LinksRaw, jointvars, isolvejointvars)
  File "/usr/local/lib/python2.7/dist-packages/openravepy/_openravepy_/ikfast.py", line 2796, in solveFullIK_TranslationDirection5D
    coupledsolutions,usedvars = solvemethod(rawpolyeqs2[index],newsolvejointvars,endbranchtree=[AST.SolverSequence([endbranchtree2])], AllEquationsExtra=AllEquations)
  File "/usr/local/lib/python2.7/dist-packages/openravepy/_openravepy_/ikfast.py", line 5226, in solveLiWoernleHiller
    hassinglevariable |= any([all([__builtin__.sum(monom)==monom[i] for monom in newpeq.monoms()]) for i in range(3)])
IndexError: tuple index out of range

Is there a recommended way to get IKfast to generate a cpp or maybe even get the normal KDL to work reliably for my 5 dof system? I would really appreciate any kind of help to get this to work, thanks

Here's the picture of the bot from RViz

image description

2017-01-03 09:09:58 -0500 commented answer Integrate actual robot into moveit(other way than ros_control?)

Hey @adolfo-rodriguez-t, my hardware has an inbuilt position control algo(PID), so i dont actually need the PID control etc from ros_control. If i just need moveit's IK and collision detection, is it ok if I implement these actions and publisher, will I lose anything if I dont implement ros_control?

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2016-10-25 15:04:04 -0500 commented answer Error while launching demo.launch in custom moveit config

Hm. The MSA should have generated a complete ROS package for you. If that was not the case, then it'd be nice if you could report that at ros-planning/moveit/issues. MSA generates a package,I meant that I needed to move that folder to ./src/ in my workspace and run catkin_make to make it work

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2016-10-24 15:51:10 -0500 commented answer Error while launching demo.launch in custom moveit config

Yes, putting the generated folder into a package file structure (as mentioned here ) works. Also before running the launch file, I had to ensure roscore is running(I'd got stuck once, because it wasn't running) Thanks!

2016-10-24 15:48:59 -0500 marked best answer Error while launching demo.launch in custom moveit config

I have generated a moveit configuration from a custom URDF using the MoveIt Setup assistant and this tutorial(http://wiki.ros.org/Industrial/Tutorials/Create_a_MoveIt_Pkg_for_an_Industrial_Robot). I have been able to generate all the files in the config and launch folders as well. But, the problem occurs when I try to launch the demo.launch file using roslaunch.

Since this is a custom URDF, there's no package name, hence I simply use this command to launch the file

roslaunch ./launch/demo.launch

Everytime I try to do this, I get an error like this

... logging to /home/tarang/.ros/log/4bbd5ee2-924a-11e6-9522-4ceb427f02d3/roslaunch-HP-dv6-19948.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.

Invalid <arg> tag: manip_moveit_config
ROS path [0]=/opt/ros/indigo/share/ros
ROS path [1]=/home/tarang/ros_try/urdftry/robotis_try/catkin_Ws/src
ROS path [2]=/opt/ros/indigo/share
ROS path [3]=/opt/ros/indigo/stacks. 

Arg xml is <arg default="$(find manip_moveit_config)/default_warehouse_mongo_db" name="db_path"/>
The traceback for the exception was written to the log file

Here, manip_moveit_config is the name of the folder in which I saved my moveit config (in the last step of the setup assistant)

What am I missing here? Do I need to perform any other steps(besides those mentioned in the tutorial) to get it to work?

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2016-10-23 06:53:08 -0500 commented answer Getting real time torque values from Rviz during move execution

I ended up using Matlab's SimMechanics finally. I only wanted the dynamics values in a few cases and simmechanics took less time than modifying the code. Thanks

2016-10-23 06:49:29 -0500 asked a question Using MoveIt programmatically and integrating with ros_control

I have a question about using moveit for my custom 6 dof manipulator robot. I am pretty new to ROS, and I really hope to learn from the community.

Basically I want to go from a URDF file to actually programmatically sending commands to my robot after planning trajectories using moveit.

From the various tutorials, I have figured that this is what i have to do

  1. Generate the URDF from the CAD model using the Solidworks plugin.
  2. Use the URDF to generate a MoveIt package using the MoveIt setup assistant.
  3. Now if I wanted to use the GUI, I could import my model into RViz and manually execute the planning, but that's not what I want, I want to do so programmatically(ideally through python/rospy, but C++ is also OK)
  4. Use ROS control to write a driver interface for communicating to the actual hardware.

I have questions about Step 3 and 4.

How do I programmatically control my own robot?

The MoveIt MoveGroup tutorial here has an example of the API but critical things(like, how do I use my robot's files?) are not clear here. How do I import my robots files(or direct MoveIt to it) in the script to ensure the calculations are done properly? I understand MoveIt commander is the python interface, but is there any example using the MoveIt Commander and a description of its API? Could somebody link to Open source code for open robots that I can see and learn.

Can you link me to any code which runs on a robot other than the PR2, that I can run and test on my system?

Also, How do I connect Ros_control and MoveIt? I have looked into the ros control boilerplate repository which has some pointers on writing the driver, but I cant find any documentation on the interface between the two.

I want to use MoveIt for my custom robotic arm and have reached the stereotypical cliff that occurs after reading through and doing the common tasks in the various tutorials and videos on ROS.

Thanks!

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2016-10-15 06:46:43 -0500 commented answer Error while launching demo.launch in custom moveit config

And should i then rebuild and source the setup files of this workspace?

2016-10-15 06:46:07 -0500 commented answer Error while launching demo.launch in custom moveit config

By custom urdf, I mean I have a urdf file which I imported to the MSA(It didnt need any package name). Now the MSA generates a set of files into a configured folder with the CMakelists and package files I used the folder name manip_moveit_config. Should I make a workspace with these files in /src?

2016-10-15 04:17:38 -0500 commented question Error while launching demo.launch in custom moveit config

If i run roslaunch manip_moveit_config demo.launch I getthis

> roslaunch manip_moveit_config demo.launch
[demo.launch] is neither a launch file in package [manip_moveit_config] nor is [manip_moveit_config] a launch file name
The traceback for the exception was written to the log file