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google / brax

Massively parallel rigidbody physics simulation on accelerator hardware.
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Adding rangefinder sensors to a robot #420

Closed eleninisioti closed 8 months ago

eleninisioti commented 8 months ago

I would like to add rangefinder sensors on a robot. They are available according to the mujoco docs (https://mujoco.readthedocs.io/en/stable/XMLreference.html#sensor) but I cannot find any examples out there

I tried to do it by modifying the ant xml with a tag <site name="range_finder_1" pos="0.25 0 0.5"/> inside the robot body and a tag <sensor name="range_finder_1_sensor" site="torso:range_finder_1" type="range"/> but am getting an error that sensor is undefined when calling mujoco.MjModel.from_xml_string

btaba commented 8 months ago

Hi @eleninisioti , Brax doesn't support sensors, you should post here for help creating the rangefinder sensor: https://github.com/google-deepmind/mujoco

eleninisioti commented 4 months ago

I am re-attempting this. After checking how sensors are added in mujoco, I made an xml file for an ant with a rangefinder on its torso that I paste at the end. It follows an example provided by mujoco

What is not clear to me is how I can get information from this sensor through the brax pipeline state. Is this already handled so that the data read from the sensor are somewhere in the brax pipeline state? Or is new code needed? I imagine it's the latter as you said that brax does not support sensors. In that case I'd appreciate any help with where in brax to add this functionality.

<mujoco model="ant">
  <compiler angle="degree" coordinate="local" inertiafromgeom="true"/>
  <option timestep="0.01" iterations="4" />
  <custom>
    <!-- brax custom params -->
    <numeric data="0.0 0.0 0.55 1.0 0.0 0.0 0.0 0.0 1.0 0.0 -1.0 0.0 -1.0 0.0 1.0" name="init_qpos"/>
    <numeric data="1000" name="constraint_limit_stiffness"/>
    <numeric data="4000" name="constraint_stiffness"/>
    <numeric data="10" name="constraint_ang_damping"/>
    <numeric data="20" name="constraint_vel_damping"/>
    <numeric data="0.5" name="joint_scale_pos"/>
    <numeric data="0.2" name="joint_scale_ang"/>
    <numeric data="0.0" name="ang_damping"/>
    <numeric data="1" name="spring_mass_scale"/>
    <numeric data="1" name="spring_inertia_scale"/>
    <numeric data="15" name="solver_maxls"/>
  </custom>
  <default>
    <joint armature="1" damping="1" limited="true"/>
    <geom contype="0" conaffinity="0" condim="3" density="5.0" friction="1 0.5 0.5"/>
  </default>
      <default class="rangefinder"><site type="capsule" size=".005 .1" material="site" /></default><asset>

  <asset>
    <texture builtin="gradient" height="100" rgb1="1 1 1" rgb2="0 0 0" type="skybox" width="100"/>
    <texture builtin="flat" height="1278" mark="cross" markrgb="1 1 1" name="texgeom" random="0.01" rgb1="0.8 0.6 0.4" rgb2="0.8 0.6 0.4" type="cube" width="127"/>
    <texture builtin="checker" height="100" name="texplane" rgb1="0 0 0" rgb2="0.8 0.8 0.8" type="2d" width="100"/>
    <material name="MatPlane" reflectance="0.5" shininess="1" specular="1" texrepeat="60 60" texture="texplane"/>
    <material name="geom" texture="texgeom" texuniform="true"/>
      <material name="site" rgba=".5 .5 .5 .3" />

  </asset>
  <worldbody>
    <light cutoff="100" diffuse="1 1 1" dir="-0 0 -1.3" directional="true" exponent="1" pos="0 0 1.3" specular=".1 .1 .1"/>
    <geom conaffinity="1" condim="3" material="MatPlane" name="floor" pos="0 0 0" size="40 40 40" type="plane"/>
    <body name="torso" pos="0 0 0.75">
      <camera name="track" mode="trackcom" pos="0 -3 0.3" xyaxes="1 0 0 0 0 1"/>
      <geom name="torso_geom" pos="0 0 0" size="0.25" type="sphere"/>
      <joint armature="0" damping="0" limited="false" margin="0.01" name="root" pos="0 0 0" type="free"/>
      <body name="front_left_leg" pos="0 0 0">
        <geom fromto="0.0 0.0 0.0 0.2 0.2 0.0" name="aux_1_geom" size="0.08" type="capsule"/>
        <body name="aux_1" pos="0.2 0.2 0">
          <joint axis="0 0 1" name="hip_1" pos="0.0 0.0 0.0" range="-30 30" type="hinge"/>
          <geom fromto="0.0 0.0 0.0 0.2 0.2 0.0" name="left_leg_geom" size="0.08" type="capsule"/>
          <body pos="0.2 0.2 0">
            <joint axis="-1 1 0" name="ankle_1" pos="0.0 0.0 0.0" range="30 70" type="hinge"/>
            <geom fromto="0.0 0.0 0.0 0.4 0.4 0.0" name="left_ankle_geom" size="0.08" type="capsule"/>
            <geom name="left_foot_geom" contype="1" pos="0.4 0.4 0" size="0.08" type="sphere" mass="0"/>
          </body>
        </body>
        <site class="rangefinder" type="sphere" name="target_compass" />

      </body>
      <body name="front_right_leg" pos="0 0 0">
        <geom fromto="0.0 0.0 0.0 -0.2 0.2 0.0" name="aux_2_geom" size="0.08" type="capsule"/>
        <body name="aux_2" pos="-0.2 0.2 0">
          <joint axis="0 0 1" name="hip_2" pos="0.0 0.0 0.0" range="-30 30" type="hinge"/>
          <geom fromto="0.0 0.0 0.0 -0.2 0.2 0.0" name="right_leg_geom" size="0.08" type="capsule"/>
          <body pos="-0.2 0.2 0">
            <joint axis="1 1 0" name="ankle_2" pos="0.0 0.0 0.0" range="-70 -30" type="hinge"/>
            <geom fromto="0.0 0.0 0.0 -0.4 0.4 0.0" name="right_ankle_geom" size="0.08" type="capsule"/>
            <geom name="right_foot_geom" contype="1" pos="-0.4 0.4 0" size="0.08" type="sphere" mass="0"/>
          </body>
        </body>
      </body>
      <body name="back_leg" pos="0 0 0">
        <geom fromto="0.0 0.0 0.0 -0.2 -0.2 0.0" name="aux_3_geom" size="0.08" type="capsule"/>
        <body name="aux_3" pos="-0.2 -0.2 0">
          <joint axis="0 0 1" name="hip_3" pos="0.0 0.0 0.0" range="-30 30" type="hinge"/>
          <geom fromto="0.0 0.0 0.0 -0.2 -0.2 0.0" name="back_leg_geom" size="0.08" type="capsule"/>
          <body pos="-0.2 -0.2 0">
            <joint axis="-1 1 0" name="ankle_3" pos="0.0 0.0 0.0" range="-70 -30" type="hinge"/>
            <geom fromto="0.0 0.0 0.0 -0.4 -0.4 0.0" name="third_ankle_geom" size="0.08" type="capsule"/>
            <geom name="third_foot_geom" contype="1" pos="-0.4 -0.4 0" size="0.08" type="sphere" mass="0"/>
          </body>
        </body>
      </body>
      <body name="right_back_leg" pos="0 0 0">
        <geom fromto="0.0 0.0 0.0 0.2 -0.2 0.0" name="aux_4_geom" size="0.08" type="capsule"/>
        <body name="aux_4" pos="0.2 -0.2 0">
          <joint axis="0 0 1" name="hip_4" pos="0.0 0.0 0.0" range="-30 30" type="hinge"/>
          <geom fromto="0.0 0.0 0.0 0.2 -0.2 0.0" name="rightback_leg_geom" size="0.08" type="capsule"/>
          <body pos="0.2 -0.2 0">
            <joint axis="1 1 0" name="ankle_4" pos="0.0 0.0 0.0" range="30 70" type="hinge"/>
            <geom fromto="0.0 0.0 0.0 0.4 -0.4 0.0" name="fourth_ankle_geom" size="0.08" type="capsule"/>
            <geom name="fourth_foot_geom" contype="1" pos="0.4 -0.4 0" size="0.08" type="sphere" mass="0"/>
          </body>
        </body>
      </body>
    </body>
  </worldbody>
  <actuator>
    <motor ctrllimited="true" ctrlrange="-1.0 1.0" joint="hip_4" gear="150"/>
    <motor ctrllimited="true" ctrlrange="-1.0 1.0" joint="ankle_4" gear="150"/>
    <motor ctrllimited="true" ctrlrange="-1.0 1.0" joint="hip_1" gear="150"/>
    <motor ctrllimited="true" ctrlrange="-1.0 1.0" joint="ankle_1" gear="150"/>
    <motor ctrllimited="true" ctrlrange="-1.0 1.0" joint="hip_2" gear="150"/>
    <motor ctrllimited="true" ctrlrange="-1.0 1.0" joint="ankle_2" gear="150"/>
    <motor ctrllimited="true" ctrlrange="-1.0 1.0" joint="hip_3" gear="150"/>
    <motor ctrllimited="true" ctrlrange="-1.0 1.0" joint="ankle_3" gear="150"/>
  </actuator>
  <sensor><rangefinder name="target_compass" site="target_compass" /></sensor>

</mujoco>

Pinging @btaba as this is a closed issue so may pass unnoticed.