Problem using xpos to obtain the location of the xml file loaded model #1985

MingchaoQi · 2024-05-18T18:16:28Z

MingchaoQi
May 18, 2024

Hi,

I'm a student and I'm trying to use MuJoCo for homework.

I'm looking for some help with obtaining joint position coordinates.

I wrote an xml file to represent the drawer.

        <geom material="MatRedWood" pos="-0.11 0 0.065" size="0.008 0.112 0.064" group="1" type="box" mass=".05"/>
        <geom material="MatRedWood" pos="0.11 0 0.065" size="0.008 0.112 0.064" group="1" type="box" mass=".05"/>
        <geom material="MatRedWood" pos="0 0.092 0.062" size="0.102 0.008 0.064" group="1" type="box" mass=".05"/>
        <geom material="MatRedWood" pos="0 -0.008 0.004" size="0.102 0.102 0.014" group="1" type="box" mass=".05"/>
        <geom material="MatRedWood" pos="0 0.01 0.121" size="0.102 0.102 0.008" group="1" type="box" mass=".05"/>
        <geom material="MatRedWood" pos="-0.102 -0.1 0.065" size="0.012 0.012 0.064" group="1" type="box" mass=".05"/>
        <geom material="MatRedWood" pos="0.102 -0.1 0.065" size="0.012 0.012 0.064" group="1" type="box" mass=".05"/>
        <site name="base_center" pos="0.0 0.0 0.001" size="0.02" rgba="0 0 1 0" />

        <body name="drawer_link" pos="0 -0.01 0.076">
          <inertial pos="0 0 0.35" quat="0.5 0.5 0.5 0.5" mass="14.0" diaginertia="0.923301 0.764585 0.168533" />
          <joint type="slide" range="-0.1 0" limited="true" axis="0 1 0" name="goal_slidey" pos="0 0 0" damping="100.0" frictionloss="1"/>
            <geom material="MatRedWood" pos="0 -0.095 0.007" size="0.088 0.010 0.046" group="1" type="box" mass=".04"/>
            <geom material="MatRedWood" pos="0 0.065 0.008" size="0.095 0.008 0.028" group="1" type="box" mass=".04"/>
            <geom material="MatRedWood" pos="-0.072 0 0.00" size="0.008 0.084 0.028" group="1" type="box" mass=".04"/>
            <geom material="MatRedWood" pos="0.072 0 0.00" size="0.008 0.084 0.028" group="1" type="box" mass=".04"/>
            <geom material="MatRedWood" pos="0 0 -0.04" size="0.08 0.09 0.008" group="1" type="box" mass=".04"/>
            <geom material="MatCeramic" euler="1.571 0 0" pos="-0.05 -0.13 0.04" size="0.009 0.03" group="1" type="capsule" mass=".06"/>
            <geom material="MatCeramic" euler="0 1.57 0" pos="0 -0.16 0.04" size="0.009 0.05" group="1" type="capsule" mass=".06"/>
            <geom material="MatCeramic" euler="1.57 0 0" pos="0.05 -0.13 0.04" size="0.009 0.03" group="1" type="capsule" mass=".06"/>
            <site name="slide_handle" pos="0 -0.16 0.04" size="0.02" rgba="0 0 1 0" />

        </body>
      </body>
    </body>
    <site name="bottom_site" pos="0 0 -0.3" rgba="0 0 0 0" size="0.005"/>
    <site name="top_site" pos="0 0 0.3" rgba="0 0 0 0" size="0.005"/>
    <site name="horizontal_radius_site" pos="0.3 0 0" rgba="0 0 0 0" size="0.1"/>
  </body>
</worldbody>

Here I want to get the position coordinates of the joint, but the coordinates obtained are always [0, 0, 0]. Here is my code:
self.object_joint_ids["cabinet_joint"] = self.sim.model.joint_name2id(self.cabinet_object.cabint_joint)
（or self.cabinet_qpos_addrs = self.sim.model.get_joint_qpos_addr(self.cabinet_object.joints[0])）
cabinet_joint_pos = self.sim.data.xpos[self.cabinet_qpos_addrs]
Can you answer this for me? Thanks you!

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Problem using xpos to obtain the location of the xml file loaded model #1985

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Problem using xpos to obtain the location of the xml file loaded model #1985

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MingchaoQi May 18, 2024

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MingchaoQi
May 18, 2024