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2019-12-20 08:54:45 -0500 marked best answer Spawning multiple robots each with a controller in the same namespace as the controller_manager

I have a problem when trying to start controllers for multiple robots that they cannot find the controller_manager

[WARN] [1498038782.062813, 84.949000]: Controller Spawner couldn't find the expected controller_manager ROS interface.

I am using the plugin in the .xacro file like so:

<gazebo>
    <plugin name="gazebo_ros_control" filename="libgazebo_ros_control.so">
      <robotNamespace>/</robotNamespace>
    </plugin>
</gazebo>

and then launching each robot in a group with a different namespace.

What am I doing wrong?

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2017-08-29 09:40:27 -0500 edited answer Import URDF Model into SDF

These are the two lines of code you need: rosrun xacro xacro --inorder robot.xacro > robot.urdf gz sdf -p robot.urdf

2017-08-29 09:40:07 -0500 answered a question SDF file is not supported in ROS

I do not completely understand if you have the .xacro file apart from the SDF file. If you do, just generate the .urdf f

2017-08-29 09:32:06 -0500 answered a question Import URDF Model into SDF

These are the two lines of code you need: rosrun xacro xacro robot.xacro > robot.urdf gz sdf -p robot.urdf > robo

2017-07-31 07:15:12 -0500 marked best answer Robot tilting problem on linear acceleration

Hello, I am trying to simulate someting close to the Nexus 3-wheeled platform.

When I accelerate with 2 wheels in the direction of the third, the latter wheel gets raised into the air. I used the fomulas on wikipedia to calculate my inertia. For the mass I tried with 10, 100, 200 kg with the same tilting result.

I mananged to set the friction directly in the .sdf file generated from my urdf.

<friction>
  <ode>
    <mu>0.9</mu>
    <mu2>0.001</mu2>
    <fdir1>0 1.0 0</fdir1>
  </ode>
</friction>

(I set it directly in the .sdf file because i noticed another problem described here.)

I also setup the joint model stiffness parameters kp, kd like so:

  <contact>
    <ode>
      <kp>1e+08</kp>
      <kd>1</kd>
    </ode>
  </contact>

in order to have some stiff wheels when in contact with the ground plane, otherwise they pass through.

Would I need to setup something else? I am using ros-kinetic and the gazebo delivered with it, Gazebo7. (I use ros_control ( a modified version of diff_drive_controller for the 3-wheeled base) and of course continuous joints)

Tnx and regards!

UPDATE

I also had a small arm on top of my robot, with a really small weight compared to the base but with it's own inertia. I deleted all that and now I just have a base with 3 wheels and it works fine. For now it's ok for what I need but for the future I will need the arm also.

2017-07-31 07:15:06 -0500 edited answer Robot tilting problem on linear acceleration

So i had this problem because of a prismatic joint I was using: I managed to use velocity_controllers/JointPositionCont

2017-07-31 07:14:22 -0500 answered a question Robot tilting problem on linear acceleration

So i had this problem because of a prismatic joint I was using: I managed to use velocity_controllers/JointPositionCont

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2017-07-07 03:58:45 -0500 marked best answer How to: Use source installed version of Gazebo

I have ROS kinetic installed with gazebo_ros and all but I have to modify the simulator in order to skip this error.

How can I use the newly source copiled version of Gazebo 7?

2017-07-07 03:58:40 -0500 commented answer How to: Use source installed version of Gazebo

That worked, thanks. So my question is answered but I still have to find out how to spawn my robot in there because I ca

2017-07-07 03:15:18 -0500 commented answer How to: Use source installed version of Gazebo

Thanks for the answer. this would work if I am trying to use ros with it? I need to use gazebo_ros, which uses the defau

2017-07-06 08:11:06 -0500 edited question How to: Use source installed version of Gazebo

How to: Use source installed version of Gazebo I have ROS kinetic installed with gazebo_ros and all but I have to modify

2017-07-06 08:10:46 -0500 asked a question How to: Use source installed version of Gazebo

How to: Use source installed version of Gazebo I have ROS kinetic installed with gazebo_ros and all but I have to modify

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2017-07-05 06:20:46 -0500 edited answer Setting friction params

Very important: fdir = direction of mu1 in the collision local reference frame SO i was setting the friction all wrong

2017-07-05 03:42:16 -0500 edited answer Setting friction params

Very important: fdir = direction of mu1 in the collision local reference frame SO i was setting the friction all wrong

2017-07-05 03:42:04 -0500 marked best answer Setting friction params

Ok guys, is any of you open to explain this in a simplified matter, or on a specific example? We all usually need friction for wheels; so If you have a wheel, turning on the x direction. You would want to have friction on the x direction. and on the y also so the wheel does not slip on the sides. So mu = mu2. But if you want to model an omniwheel, you would like the y direction to have no friction, so the wheel can actually slip that side. So you set up the mu2 = 0 In case your wheel is not oriented on the specified axes you can change the direction with fdir1.

I keep on seing people advising friction of 100 or some other values that are not comprised in the 0..1 interval specified by the sdf documentation. What is the catch with that?

I played around with the friction, but apparently for the same settings, my wheels react differently from a run to another.

I try to simulate a 3 omniwheeled robot base. And I've just come to realise there is no friction in the sdf code generated for gazebo from the xacro file written.

code URDF:

<surface>
    <friction>
      <ode>
        <mu>1</mu>
        <mu2>0</mu2>
        <fdir1>0 1.0 0</fdir1>
        <implicit_spring_damper>true</implicit_spring_damper>
      </ode>
    </friction>
  </surface>

generated code SDF with gw sdf -p:

  <surface>
      <contact>
        <ode>
          <kp>1e+06</kp>
          <kd>1</kd>
        </ode>
      </contact>
      <friction>
        <ode/>
      </friction>
    </surface>

A part of my question can be also found here, but nobody actually answered that part.

2017-07-05 03:42:03 -0500 edited answer Setting friction params

Very important: fdir = direction of mu1 in the collision local reference frame SO i was setting the friction all wrong

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2017-06-30 02:41:23 -0500 commented question Robot wabbles in gazebo

Let the x,y,z of the wheel be set up only in the joint; so your joint will position your wheel relative to the chasis. A

2017-06-30 02:31:15 -0500 commented question How can I lock one axis of ball joint in gazebo?

You can look into revolute2 joints, where you can set up 2 axis. See here on the joint type and axis and axis2 tags http

2017-06-30 02:30:59 -0500 commented question How can I lock one axis of ball joint in gazebo?

You can look into revolute2 joints, where you cqn set up 2 axis. See here on the joint type and axis and axis2 tags http

2017-06-29 06:18:38 -0500 commented question Robot tilting problem on linear acceleration

Yes the third wheel (aith the base link too, not just the wheel alone), like it had a huge inertial value on the robot.

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2017-06-28 08:45:05 -0500 edited question Robot tilting problem on linear acceleration

Robot tilting problem on linear acceleration Hello, I am trying to simulate someting close to the Nexus 3-wheeled platfo

2017-06-28 08:42:46 -0500 commented question Robot tilting problem on linear acceleration

Yes the third wheel, like it had a huge inertial value on the robot. Not too high because my robot is low so it hits the

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2017-06-26 08:22:19 -0500 edited question Robot tilting problem on linear acceleration

Robot tilting problem on linear acceleration Hello, I am trying to simulate someting close to the Nexus 3-wheeled platfo

2017-06-26 07:57:58 -0500 edited question Robot tilting problem on linear acceleration

Robot tilting problem on linear acceleration Hello, I am trying to simulate someting close to the Nexus 3-wheeled platfo

2017-06-26 07:54:06 -0500 edited question Robot tilting problem on linear acceleration

Robot tilting problem on linear acceleration Hello, I am trying to simulate someting close to the Nexus 3-wheeled platfo

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