Real-Time Physics Simulation Forum 2020-02-21T20:59:17+00:00 https://pybullet.org/Bullet/phpBB3/app.php/feed/topic/12852 2020-02-21T20:59:17+00:00 2020-02-21T20:59:17+00:00 https://pybullet.org/Bullet/phpBB3/viewtopic.php?p=42633#p42633 <![CDATA[Re: Model keeps swinging back and forth and is not fixed to the ground]]> Alternatively, set the mass of the first (base) link to zero.

See also the PyBullet quickstart guide for more info in general.
https://docs.google.com/document/d/10sX ... e70wns7io3

Statistics: Posted by bullet_team — Fri Feb 21, 2020 8:59 pm

]]> 2020-02-06T05:03:42+00:00 2020-02-06T05:03:42+00:00 https://pybullet.org/Bullet/phpBB3/viewtopic.php?p=42614#p42614 <![CDATA[Re: Model keeps swinging back and forth and is not fixed to the ground]]> Statistics: Posted by LocknutBushing — Thu Feb 06, 2020 5:03 am

]]> 2020-02-05T11:17:49+00:00 2020-02-05T11:17:49+00:00 https://pybullet.org/Bullet/phpBB3/viewtopic.php?p=42612#p42612 <![CDATA[Re: Model keeps swinging back and forth and is not fixed to the ground]]> I added another ground plane on my own directly into the urdf file by adding another link (the ground) and a joint
between this link and the base of my model like below. Pay attention that I used the Base link from my model as the parent and the ground
as child, instead of doing it the other way around as one would normally do.

Code: 

   <link name="ground">     <inertial>      <mass value="0.0"/>      <inertia ixx="0.0" ixy="0.0" ixz="0.0" iyy="0.0" iyz="0.0" izz="0.0"/>    </inertial>    <visual>      <geometry>        <box size="10 10 -0.0001" />      </geometry>      <material name="red" />    </visual>    <collision>      <geometry>        <box size="10 10 -0.0001" />      </geometry>    </collision>  </link>  <joint name="ground_joint" type="fixed">     <parent link="Base" />     <child link="ground" />  </joint>

Statistics: Posted by simont — Wed Feb 05, 2020 11:17 am

]]> 2020-01-29T09:05:34+00:00 2020-01-29T09:05:34+00:00 https://pybullet.org/Bullet/phpBB3/viewtopic.php?p=42600#p42600 <![CDATA[Re: Model keeps swinging back and forth and is not fixed to the ground]]> So here is the original code:

Code: 

 self.model = p.loadURDF(filename, flags=p.URDF_USE_SELF_COLLISION)
So I tried this one, but it would not change anything so far. Any idea?

Code: 

 self.model = p.loadURDF(filename, flags=p.URDF_USE_SELF_COLLISION, useFixedBase=1)

I'm not entirely sure what you mean by swinging back and forth, that's especially confusing terminology when you're already talking about a pendulum. But if you mean the base of the pendulum is shaking, you can make it fixed in place easily:

Code: 

robot = p.loadURDF("[insert urdf path here]", useFixedBase=1)
This fixes the base component of the URDF model.

Statistics: Posted by simont — Wed Jan 29, 2020 9:05 am

]]> 2020-01-26T04:47:55+00:00 2020-01-26T04:47:55+00:00 https://pybullet.org/Bullet/phpBB3/viewtopic.php?p=42594#p42594 <![CDATA[Re: Model keeps swinging back and forth and is not fixed to the ground]]>

Code: 

robot = p.loadURDF("[insert urdf path here]", useFixedBase=1)
This fixes the base component of the URDF model.

Statistics: Posted by LocknutBushing — Sun Jan 26, 2020 4:47 am

]]> 2020-01-23T12:47:01+00:00 2020-01-23T12:47:01+00:00 https://pybullet.org/Bullet/phpBB3/viewtopic.php?p=42591#p42591 <![CDATA[Model keeps swinging back and forth and is not fixed to the ground]]> I have the inverted pendulum modell below and it should be trained with reinforcement learning in pybullet.
The problem now ist, that it doesn't stand still but it swings back and forth. Does anybody of you have an idea
what could be the reason or how I could fix the model to the ground?

Code: 

<?xml version="1.0"    ?><robot name="Cartpole"  >  <joint name="Rotation" type="continuous">      <parent link="Cart"/>    <child link="Shaft"/>    <origin rpy="0  0  0" xyz="0.0215  0.247   0.0435"/>    <axis xyz="1  0  0"/>    <limit effort="0.0" lower="0.0" upper="0.0" velocity="0.0"/>  </joint>  <joint name="Cart_joint" type="prismatic">    <parent link="Base"/>    <child link="Cart"/>    <origin rpy="0  0  0" xyz="-0.04147 -0.31058  0.22851"/>    <axis xyz="0 -1  0"/>    <limit effort="0.0" lower="-0.23555" upper="0.23555" velocity="0.0"/>  </joint>  <joint name="Pole_Shaft" type="fixed">    <parent link="Shaft"/>    <child link="Pole"/>    <origin rpy="0  0  0" xyz="0.0193  0      0.007"/>    <axis xyz="0  0  0"/>    <limit effort="0" lower="0" upper="0" velocity="0"/>   </joint>  <link name="Cart">    <inertial>      <mass value="0.4494280957660571"/>      <origin rpy="0  0  0" xyz="0  0  0"/>    <inertia ixx="0.034344216689805106" ixy="-0.0013555840592494157" ixz="0.005746023053830929" iyy="0.033575305370647346" iyz="0.007655119926892856"     izz="0.0029338994617400297"/>      </inertial>             <collision name="Cart_collision">      <origin rpy="0  0  0" xyz="-0.00606  0.24716  0.03996"/>      <geometry>        <mesh filename="package:///home/simon_tiessen/sim-to-real-ai/example_robots/urdf_cartpole/meshes/CAD/Cart.stl" scale="0.001 0.001 0.001"/>      </geometry>      </collision>    <visual name="Cart_visual">      <origin rpy="0  0  0" xyz="-0.00606  0.24716  0.03996"/>      <geometry>        <mesh filename="package:///home/simon_tiessen/sim-to-real-ai/example_robots/urdf_cartpole/meshes/CAD/Cart.stl" scale="0.001 0.001 0.001"/>      </geometry>    </visual>  </link>   <link name="Shaft">    <inertial>      <mass value="0.024209988665072436"/>      <origin rpy="0  0  0" xyz="0  0  0"/>      <inertia ixx="0.00188987952436807" ixy="-1.1706804306416182e-05" ixz="5.008066577766269e-05" iyy="0.0017943029340322224" iyz="0.0004187314228447953" izz="0.00010090272031144335"/>    </inertial>    <collision name="Shaft_collision">      <origin rpy="0  0  0" xyz="0.01237  0       0"/>      <geometry>        <mesh filename="package:///home/simon_tiessen/sim-to-real-ai/example_robots/urdf_cartpole/meshes/CAD/Shaft.stl" scale="0.001 0.001 0.001"/>      </geometry>    </collision>    <visual name="Shaft_visual">      <origin rpy="0  0  0" xyz="0.01237  0       0"/>      <geometry>        <mesh filename="package:///home/simon_tiessen/sim-to-real-ai/example_robots/urdf_cartpole/meshes/CAD/Shaft.stl" scale="0.001 0.001 0.001"/>      </geometry>    </visual>  </link>  <link name="Pole">    <inertial>      <mass value="0.01797430178868597"/>      <origin rpy="0  0  0" xyz="0  0  0"/>      <inertia ixx="0.0008366739796019355" ixy="-7.689518680322801e-07" ixz="2.477907732299824e-06" iyy="0.0007640110742674137" iyz="0.0002341786839091567" izz="7.299569596665657e-05"/>    </inertial>    <collision name="Pole_collision">      <origin rpy="0  0  0" xyz="0       0      -0.07411"/>      <geometry>        <mesh filename="package:///home/simon_tiessen/sim-to-real-ai/example_robots/urdf_cartpole/meshes/CAD/Pole.stl" scale="0.001 0.001 0.001"/>      </geometry>    </collision>    <visual name="Pole_visual">      <origin rpy="0  0  0" xyz="0       0      -0.07411"/>      <geometry>        <mesh filename="package:///home/simon_tiessen/sim-to-real-ai/example_robots/urdf_cartpole/meshes/CAD/Pole.stl" scale="0.001 0.001 0.001"/>      </geometry>    </visual>  </link>  <link name="Base">    <inertial>      <mass value="222222.5459113603106216"/>      <origin rpy="0  0  0" xyz="0  0  0"/>      <inertia ixx="0.5882136684497374" ixy="-0.02906460593367471" ixz="0.0501787117673072" iyy="0.14479915583911276" iyz="0.07620661469781886" izz="0.5291431708702397"/>    </inertial>    <collision name="Base_collision">      <origin rpy="0  0  0" xyz="-0.10471 -0.14784  0.19902"/>      <geometry>        <mesh filename="package:///home/simon_tiessen/sim-to-real-ai/example_robots/urdf_cartpole/meshes/CAD/Base.stl" scale="0.001 0.001 0.001"/>      </geometry>    </collision>    <visual name="Base_visual">      <origin rpy="0  0  0" xyz="-0.10471 -0.14784  0.19902"/>      <geometry>        <mesh filename="package:///home/simon_tiessen/sim-to-real-ai/example_robots/urdf_cartpole/meshes/CAD/Base.stl" scale="0.001 0.001 0.001"/>      </geometry>    </visual>  </link></robot>
pendelum.png

Statistics: Posted by simont — Thu Jan 23, 2020 12:47 pm

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