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2020-02-21 22:47:54 -0500 asked a question Simulating a strip of addressable LEDs?

Simulating a strip of addressable LEDs? I am doing a small project using some strips of individually-addressable LEDs si

2020-02-08 13:48:52 -0500 marked best answer Gazebo 11 for Ubuntu 20.04?

Congrats on the Gazebo 11 release. I note on the project status page that Ubuntu F is listed as a supported platform:

http://gazebosim.org/#status

However, there don't seem to be packages available for gazebo11 or its dependencies available at packages.osrfoundation.org. Is there a planned timeline for Focal packages to be made available?

2020-02-07 12:34:16 -0500 commented answer Gazebo 11 for Ubuntu 20.04?

Perfect, that's just what I was looking for, thanks— I had been trying with the master branches of everything and was en

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2020-02-05 22:42:22 -0500 commented answer Gazebo 11 for Ubuntu 20.04?

Alternatively, are there updated instructions anywhere for building gz11 sanely from source using a workspace builder li

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2020-02-05 22:41:58 -0500 commented answer Gazebo 11 for Ubuntu 20.04?

Upstream looks like it'll get Gazebo 9.6 again, based on libsdformat6 and all the other dependencies being in place for

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2020-02-04 16:15:17 -0500 asked a question Gazebo 11 for Ubuntu 20.04?

Gazebo 11 for Ubuntu 20.04? Congrats on the Gazebo 11 release. I note on the project status page that Ubuntu F is listed

2016-08-17 20:50:31 -0500 commented answer Simulating Actuated Joint Stiffness

But the real system doesn't need to compensate for gravity— it's just not backdriveable.

2016-08-16 19:07:14 -0500 commented answer Simulating Actuated Joint Stiffness

We aren't actually using a screw joint, at least for now it's a simple prismatic joint. I suppose we could maybe paper over the problem with an extremely large amount of friction?

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2015-10-31 12:30:48 -0500 marked best answer Mecanum simulation possible using directional friction?

I've been following with interest the evolving story for how to simulate mecanum wheels in Gazebo— planar move, fake casters, etc.

However, it was recently pointed out to me that it may be possible to do a pretty accurate simulation of a mecanum wheel using a single cylinder with directional friction on the circumference. Is this a realistic possibility? Is there a good example of this somewhere to experiment with? The idea of using a pure-SDF solution without needing a custom plugin for this robot is extremely appealing, if it's possible.

Thanks for any pointers or thoughts.


Edit: These are the mecanum wheels in my project: http://www.andymark.com/product-p/am-0137.htm

2015-09-24 14:24:01 -0500 marked best answer Jackal simulator flipping and flying in Gazebo 5.1

Hi all,

I'm working on a platform related to Jackal, using Jackal's simulator as a base. This is a URDF-described robot which leverages gazebo_ros_control and diff_drive_controller. It seems to work great in Gazebo 2. Description here:

https://github.com/jackal/jackal/blob/indigo-devel/jackal_description/urdf/jackal.urdf.xacro https://github.com/jackal/jackal/blob/indigo-devel/jackal_description/urdf/jackal.gazebo

Unfortunately in Gazebo 5.1, issuing a command causes the robot to do nothing, and then abruptly leap forward in summersaults. It's as if the wheels are being held still and the chassis is being turned relative to the stationary wheel. This is especially apparent when I place the robot on a box so that the wheels are not in contact with anything at all.

Any thoughts what's going on here? Is there a good reference for a wheeled base working in Gazebo 5 with which I can compare?


To reproduce, clone the following repos into your workspace:

And run the following:

roslaunch jackal_gazebo jackal_world.launch
roslaunch jackal_viz view_robot.launch

You should be able to drive with the interactive markers, which will trigger the behaviour.

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2015-07-28 13:47:48 -0500 marked best answer Visualizing friction?

I'm trying to simulate a mecanum wheel using a plugin which dynamically sets directional friction (related question). One of the tricky parts is that it's difficult to assess whether my plugin is having the desired results without a way to visualize the friction— I can show the contact points between the wheels and the ground plane, but fdir1/mu/mu2 are completely opaque.

Is there some way to visualize these which I'm not seeing, or a plugin which can add an overlay to gzclient?

Thanks

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2015-07-28 13:46:32 -0500 answered a question Recent questions missing?

The forum was hacked and got reverted to an older database backup. You may be able to recover your question from Google's cache, but either way, it will need to be re-asked.

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2015-07-03 23:06:25 -0500 answered a question Jackal simulator flipping and flying in Gazebo 5.1

Okay, looks like the issue has to do with the built-in PID controller which is used by Gazebo to convert a commanded joint velocity into torque/effort. There doesn't seem to be any documentation covering how this works or how to set the gains for it, but a workaround (at least for ROS robots) is to disable it and instead use the PID controller built into gazebo_ros_control. Example use:

<rosparam param="/gazebo_ros_control/pid_gains">
  front_left_wheel:
    p: 10
    i: 0.1
    d: 0
</rosparam>

No more flipping and flying robots.

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2015-07-03 11:38:03 -0500 commented question SetMaxForce deprecated in gazebo 5.0

Just moving my comment up here— I'm not sure what the answer is, but I'm seeing a similar result with the Jackal simulator: URDF which once worked with Gazebo 2 is now flying all over the place on Gazebo 5. cf. http://answers.gazebosim.org/question/8994/jackal-simulator-flipping-and-flying-in-gazebo-51/

2015-07-03 11:34:25 -0500 answered a question Failed to load plugin, no such file or directory, Gazebo 5.0 with ROS

I was having some issues like this working with Gazebo 5 on Indigo. Unless you're on Jade, make sure that gazebo_ros is in your workspace.

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2015-07-02 10:55:54 -0500 commented answer Computing transforms in a Gazebo plugin

Okay, cool. So in the short term, subtracting world poses is a reasonable workaround?

2015-07-02 10:29:44 -0500 edited question Computing transforms in a Gazebo plugin

I have a plugin, from which I'd like to modify some link parameters based on the position of the link relative to another link. What's the easiest way to get this information? My normal ROS instinct is to reach for tf2, but then I'm dependent on a bunch of external stuff which I really don't want to be, including robotstatepublisher.

So far, I'm just grabbing the GetWorldCoGPose for each link and subtracting. Is there a more elegant way to do this?

2015-07-02 09:14:22 -0500 commented answer Visualizing friction?

It does seem that they update (in the sidebar) in response to my plugin changing them. However, values alone are pretty much meaningless, especially when it's not super clear from the Gazebo documentation what direction the primary friction vector is even relative to.

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