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Model falling down when starting

asked 2013-06-28 08:24:52 -0500

atenea gravatar image

Hi!

I am having problems with my model, it oftens falls to the ground when starting. This is totally random behaviour though... Any ideas why this can be happening?

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Could you explain your question a bit more. Do you want to switch off the gravity?

Mrit91 gravatar imageMrit91 ( 2013-07-02 23:34:10 -0500 )edit

3 Answers

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answered 2013-07-24 09:24:14 -0500

nkoenig gravatar image

All the links are in exactly the same position, which is probably not what you want. You should set the pose of each link relative to the parent model.

The pose of the model should also be set so that it doesn't penetrate the ground plane on start.

It can be helpful to start the simulation paused in order to see the initial configuration of your model. Pass 'gazebo' the '-u' command line argument to start paused.

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Thanks!!! That was it. I fixed the poses and now it is working.

atenea gravatar imageatenea ( 2013-07-25 09:43:51 -0500 )edit
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answered 2013-07-17 02:20:19 -0500

atenea gravatar image

updated 2013-07-24 09:08:52 -0500

nkoenig gravatar image
<?xml version="1.0" ?>
<sdf version="1.4">
  <model name="model1">
  <static>0</static>
    <link name="chassis">

    <collision name="collision">
     <pose>0 0 0.02 0 0 0</pose>
      <geometry>
    <mesh>
          <uri>file://body.dae</uri>
      <scale>0.1 0.1 0.1</scale>
        </mesh>
      </geometry>
    </collision>

    <visual name='visual'>
     <pose>0 0 0.02 0 0 0</pose>
        <geometry>
          <mesh>
            <uri>file://body.dae</uri>
        <scale>0.1 0.1 0.1</scale>
          </mesh>
        </geometry>
      </visual>

      <inertial>
        <mass>36</mass>
    <inertia>
      <ixx>0.674</ixx>
      <ixy>0</ixy>
      <ixz>0</ixz>
      <iyy>1.298</iyy>
      <iyz>0</iyz>
      <izz>1.682</izz>
    </inertia>
      </inertial>
      <self_collide>0</self_collide>
</link>


<!-- Left Wheels and bar-->
<link name="left_wheel_mid">
    <collision name="collision">
     <pose>0 0 0.02 0 0 0</pose>
      <geometry>
    <mesh>
          <uri>file://left_wheel_mid.dae</uri>
      <scale>0.1 0.1 0.1</scale>
        </mesh>
      </geometry>
    </collision>

    <visual name="visual">
     <pose>0 0 0.02 0 0 0</pose>
      <geometry>
    <mesh>
          <uri>file://left_wheel_mid.dae</uri>
      <scale>0.1 0.1 0.1</scale>
        </mesh>
      </geometry>
    </visual>

      <inertial>
        <mass>2</mass>
    <inertia>
      <ixx>0.00606</ixx>
      <ixy>0</ixy>
      <ixz>0</ixz>
      <iyy>0.0121</iyy>
      <iyz>0</iyz>
      <izz>0.00606</izz>
    </inertia>
      </inertial>

    <self_collide>1</self_collide>
</link>

<link name="left_wheel_rear">
    <collision name="collision">
     <pose>0 0 0.02 0 0 0</pose>
      <geometry>
    <mesh>
            <uri>file://left_rear_wheel.dae</uri>
        <scale>0.1 0.1 0.1</scale>
        </mesh>
      </geometry>
      <surface>
        <friction>
     <ode>
      <mu>0.8</mu>
      <mu2>0.8</mu2>
      <slip1>0.5</slip1>
      <slip2>0</slip2>
     </ode>
       </friction>
    </surface>
    </collision>

    <visual name="visual">
     <pose>0 0 0.02 0 0 0</pose>
      <geometry>
    <mesh>
            <uri>file://left_rear_wheel.dae</uri>
        <scale>0.1 0.1 0.1</scale>
          </mesh>
      </geometry>
    </visual>

      <inertial>
        <mass>2</mass>
    <inertia>
      <ixx>0.00606</ixx>
      <ixy>0</ixy>
      <ixz>0</ixz>
      <iyy>0.0121</iyy>
      <iyz>0</iyz>
      <izz>0.00606</izz>
    </inertia>
      </inertial>



    <self_collide>1</self_collide>
</link>

<link name="left_wheel_front">
    <collision name="collision">
     <pose>0 0 0.02 0 0 0</pose>
      <geometry>
    <mesh>
          <uri>file://left_front_wheel.dae</uri>
      <scale>0.1 0.1 0.1</scale>
        </mesh>
      </geometry>
      <surface>
        <friction>
     <ode>
      <mu>0.8</mu>
      <mu2>0.8</mu2>
      <slip1>0.5</slip1>
      <slip2>0</slip2>
     </ode>
       </friction>
    </surface>
    </collision>

    <visual name="visual">
     <pose>0 0 0.02 0 0 0</pose>
      <geometry>
    <mesh>
          <uri>file://left_front_wheel.dae</uri>
      <scale>0.1 0.1 0.1</scale>
        </mesh>
      </geometry>
    </visual>

      <inertial>
        <mass>2</mass>

<!--    <pose>0 0 0 0 0 0</pose>-->

    <inertia>
      <ixx>0.00606</ixx>
      <ixy>0</ixy>
      <ixz>0</ixz>
      <iyy>0.0121</iyy>
      <iyz>0</iyz>
      <izz>0.00606</izz>
    </inertia>
      </inertial>

    <self_collide>1</self_collide>
</link>

<link name="wheels_left_bar">
    <collision name="collision">
     <pose>0 0 0.02 0 0 0</pose>
      <geometry>
    <mesh>
          <uri>file://wheels_left_bar.dae</uri>
      <scale>0.1 0.1 0.1</scale>
        </mesh>
      </geometry>
    </collision>

    <visual name='visual'>
     <pose>0 0 0.02 0 0 0</pose>
        <geometry>
          <mesh>
            <uri>file://wheels_left_bar.dae</uri ...
(more)
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Comments

So I posted now the whole model. The link that is falling down is the "chassis". I still couldn't find a way around it. I do set all links above the ground on startup. Any other ideas?

atenea gravatar imageatenea ( 2013-07-17 02:23:29 -0500 )edit
0

answered 2013-07-10 02:58:09 -0500

atenea gravatar image

updated 2013-07-24 09:07:37 -0500

nkoenig gravatar image

Hi Mrit91! Actually I do want gravity on. But a part of the model falls to the ground when starting. The model is quite big, so I am just posting the link that is falling to the ground. Any idea?

Thanks!

<model name="model1">
  <static>0</static>
    <link name='chassis'>

    <collision name="collision">
     <pose>0 0 0.02 0 0 0</pose>
      <geometry>
    <mesh>
          <uri>file://body.dae</uri>
      <scale>0.1 0.1 0.1</scale>
        </mesh>
      </geometry>
    </collision>

    <visual name='visual'>
     <pose>0 0 0.02 0 0 0</pose>
        <geometry>
          <mesh>
            <uri>file://body.dae</uri>
        <scale>0.1 0.1 0.1</scale>
          </mesh>
        </geometry>
      </visual>

      <inertial>
        <mass>36</mass>
    <inertia>
      <ixx>0.674</ixx>
      <ixy>0</ixy>
      <ixz>0</ixz>
      <iyy>1.298</iyy>
      <iyz>0</iyz>
      <izz>1.682</izz>
    </inertia>
      </inertial>
      <self_collide>0</self_collide>
</link>
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Comments

Not sure how big your model is, but you should verify that the z pose of the model allows it to rest slightly above the ground plane on startup.

iche033 gravatar imageiche033 ( 2013-07-10 18:16:02 -0500 )edit
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Asked: 2013-06-28 08:24:52 -0500

Seen: 1,961 times

Last updated: Jul 24 '13