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2020-02-14 12:17:54 -0500 marked best answer No message published to ROS Melodic from clearpath(Indigo)

Currently we have a clearpath ridgeback running Ubuntu 14.04(Indigo) that is connected to a remote PC running Ubuntu 18.04 (Melodic).

Currently I'm able or not able to do the following:

1) running rostopic list on my remote PC, I'm able to see all the topics being published by ridgeback; However, I'm not able to rostopic echo any of the above topics on my remote PC. For example, when I run

rostopic echo -c tf

There is no response on my remote PC. However, if I run the same command on my ridgeback, I can see the tf topic is being printed out.

2) When I run rostopic echo $ANYTOPIC$ on my remote PC and run rostopic info $ANYTOPIC$ on the ridgeback, I can see there is a new subscriber created for my remote PC to subscribe $ANYTOPIC$;

3) I can publish info (simple rospy publisher tutorial) from my remote PC to the ridgeback robot and the ridgeback can successfully subscribe to it and print it out; The ridgeback can publish info and my remote PC is able to subscribe to it and print it out. The problems only exist for the topics that are being published at the start-up of ridgeback.

5) This problem doesn't happen until I upgraded my PC to Ubuntu 18.04.

Can anyone provide a few thoughts?

Thanks.

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2020-02-05 17:48:55 -0500 commented answer No message published to ROS Melodic from clearpath(Indigo)

I don't think it is the IP and host name issues since my remote PC and clearpath robot is able to publish and subscribe

2020-02-05 17:48:27 -0500 edited question No message published to ROS Melodic from clearpath(Indigo)

No message published to ROS Melodic from clearpath(Indigo) Currently we have a clearpath ridgeback running Ubuntu 14.04(

2020-02-05 16:13:18 -0500 edited question No message published to ROS Melodic from clearpath(Indigo)

No message published to ROS Melodic from clearpath(Indigo) Currently we have a clearpath ridgeback running Ubuntu 14.04(

2020-02-05 16:09:29 -0500 edited question No message published to ROS Melodic from clearpath(Indigo)

No message published to ROS Melodic from clearpath(Indigo) Currently we have a clearpath ridgeback running Ubuntu 14.04(

2020-02-05 16:08:44 -0500 asked a question No message published to ROS Melodic from clearpath(Indigo)

No message published to ROS Melodic from clearpath(Indigo) Currently we have a clearpath ridgeback running Ubuntu 14.04

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2020-01-15 17:02:56 -0500 edited question Difference between python and cpp publisher/subscriber

Difference between python and cpp publisher/subscriber Hello all, I know it looks like a naive question. However, I hav

2020-01-15 17:02:07 -0500 edited question Difference between python and cpp publisher/subscriber

Difference between python and cpp publisher/subscriber Hello all, I know it looks like a naive question. However, I hav

2020-01-15 17:01:27 -0500 commented question Difference between python and cpp publisher/subscriber

We are using ROS kinetic on Ubuntu 16.04

2020-01-15 17:01:14 -0500 asked a question Difference between python and cpp publisher/subscriber

Difference between python and cpp publisher/subscriber Hello all, I know it looks like a naive question. However, I hav

2020-01-08 11:57:25 -0500 marked best answer Questions regarding ROS time synchronization

Hi all,

MY question is related to here. We have a remote PC, local PC and a jetson running at the same time. I was told that ROS time synchronization is important in this situation. My question is what would be the potential advantages of time synchronization? Could you make one counter example of what could happen if I don't perform time synchronization?

Thank you in advance.

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2020-01-08 02:16:54 -0500 commented answer Questions regarding ROS time synchronization

Again, thank you so much for your help. Kind of wonder how did you know all of this. Really appreciate it.

2020-01-08 01:41:07 -0500 commented answer Questions regarding ROS time synchronization

Thank you gvdoorn. The weird thing is that currently the entire system is not "time synchronized". But still they can re

2020-01-07 18:35:35 -0500 asked a question Questions regarding ROS time synchronization

Questions regarding ROS time synchronization Hi all, MY question is related to here. We have a remote PC, local PC and

2020-01-07 15:40:18 -0500 commented question Looking for an industry robot with joint velocity control

Yes it does, you can google it and the default ROS support for UR should give u that feature.

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2019-07-31 12:44:26 -0500 marked best answer rqt_plot trajectory_msgs/Jointrajectory/points/velocities

Hey all,

I wonder if it is possible to plot this trajectory_msgs/Jointrajectory/points/velocities in rqt_plot?

image description

I want to show the joint velocities[5], in this case -0.86621.

Thank you in advance.

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2019-03-01 16:36:39 -0500 marked best answer Camera recommendation used for depth measurement

Hi all,

First, thank you for your time to read this post. I'm a graduate student in mechanical engineering, and currently being assigned too many tasks related to computer science :( The thing we are trying to do is to get the normal vectors of the selected points located on one object. Then reconstruct the object from its visual information captured either by cameras or laser sensors. Really appreciate your help on the following questions.

  1. We are looking for a good camera for depth measurement. I'm wondering if anyone knows what's the brand or model of cameras being used in this video? This project comes from Googles AI robotics project. Also, I'd really appreciate it if you could make other camera recommendations under the same setup. Several people recommended intel cameras. But our project manager requires us to use the best camera available. Is there any other better cameras that you would recommend?
  2. This camera (the link is same as above) seems to be a monocular camera. Is there any reasons why monocular camera is being used here?
  3. I assume laser scanner could provide better performance in terms of depth measurements of the whole object under the same setup (fixed camera placed on top of the robot manipulator). The question is could we identify the selected point on the object? We could mark those selected points with different colors.
  4. From my limited understanding, laser scanners provide point cloud information (please correct me if I'm wrong). If we want to get a better understanding of how to use point cloud, such as reconstruct point cloud to form the shape (?) of the object. What classes would you recommend? I know there is a PCL library but it looks kind of confusing to me.

Thank you again for your help.

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2018-12-25 21:23:03 -0500 asked a question Point cloud data appears larger than it should be in rviz

Point cloud data appears larger than it should be in rviz Hello all, I hope some of you may help me to understand the

2018-10-11 16:22:48 -0500 marked best answer tf_echo is correct, yet no result from lookuptranform

Hey guys,

I'm using urdf withrviz to do forward kinematics related problem. My question is can we get the results of tf_echo in a script? Also, I'm looking for suggestions why this problem happened.

I could use

rosrun tf tf_echo /base /tool0

to get the correct result:

At time 1499215724.972 - Translation: [0.410, 0.191, 0.947] - Rotation: in Quaternion [0.707, 0.000, -0.000, 0.707] in RPY (radian) [1.571, 0.000, 0.000] in RPY (degree) [89.997, 0.008, 0.004]

Yet, I couldn't use

(trans, rot) = listener.lookupTransform('base', 'tool0', rospy.Time(0)), refer to here to get the transform, it would throw an exception.

I also tried

now = rospy.Time.now()

listener.waitForTransform("base", "tool0", now, rospy.Duration(10.0)) tf.Exception: . canTransform returned after 10.0023 timeout was 10.

I chagned 10 here to 0.01, 1, etc. and it always gives similar exception.

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2018-08-09 10:06:52 -0500 commented answer Camera recommendation used for depth measurement

Thank you for your camera recommendation. I guess I will go with this one before I can come back with more meaningful qu

2018-08-09 10:00:30 -0500 commented question Camera recommendation used for depth measurement

lol. I personally feel sometimes I need to be "pedantic". Thank you for the clarification.

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2018-08-09 08:29:45 -0500 marked best answer Looking for an industry robot with joint velocity control

Hey All,

Currently we are looking for an industry robot that accepts joint speed command for real-time force control. I know Universal Robot is a potential candidate. However, its payload is not enough for our project. We are looking for a robot with the minimum payload of 12 kg.

I have been searching for a while. This recommends motorman FS100 controller. I see the PR has been merged in here. My question is:

  • (1) What is the tracking performance for joint speed control? This link says he used "work-arounds" for force control. But how about its "real" performance? Is motorman joint velocity response quick enough to handle robot control on sensor feedback such as a force-torque sensor?

For Kuka robot, This link says "no RSI, no EKI" supports any velocity interfaces". Also, KUKA iiwa doesn't have the appropriate payload. I read somewhere (sorry I couldn't find its link) saing KUKA_EGM (or something similar) may be useful but I'm not sure what it is. My question would be:

  • (2) Are there any KUKA robot asides from iiwa and LWR4 supporting joint velocity control?

As for ABB, I saw ABB IRB2400 is used for the ROS-Industry GODEL project. We are doing something similar. So my question is

  • (3) Does ABB IRB2400 supports joint velocity control? If not, are there any other models do?

Finally, I couldn't find too much information on Fanuc robot.

  • (4) Does it have any joint velocity controlled robot?

The ROS driver set-ups for different robot vendors are kind of complicated for me since my major is mechanical. I would really appreciate your feedback on the selection of industry robots since these industry robots could be super expensive, and I can't return it if we chose a wrong model.

Again, thank you for your help.

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2018-08-08 22:09:21 -0500 commented question Camera recommendation used for depth measurement

Thank you so much for your guidance. I will gather all the info and then talk to the sales guy to see if I can get a goo

2018-08-08 21:45:48 -0500 edited question Camera recommendation used for depth measurement

Camera recommendation used for depth measurement Hi all, First, thank you for your time to read this post. I'm a gradua

2018-08-08 21:40:07 -0500 commented answer Camera recommendation used for depth measurement

Also, thank you for your useful suggestions on this topics.

2018-08-08 21:39:35 -0500 commented answer Camera recommendation used for depth measurement

Also, I'm wondering if you have some good laser scanners in minds? There are just so many good products on the market...