How to correctly set up collisions in MuJoCo? #2373

gemcollector · 2025-01-19T12:37:14Z

gemcollector
Jan 19, 2025

Intro

Hi!

I am a [graduate] student, I use MuJoCo for my research on robotics.

My setup

mujoco version==3.2.3
dm-control version==1.0.23

My question

problem.mp4

When I grasp objects, there is severe jittering of the object in my hand. What do you think could be the reason? The collisions are between the purple and green parts, which are typical geometric models like capsules and boxes. The hand model's mesh has been set to visual only and is not used for collisions.

Minimal model and/or code that explain my question

If you encountered the issue in a complex model, please simplify it as much as possible (while still reproducing the issue).

Model:

minimal XML

<mujoco>
  <worldbody>
    <light pos="0 0 1"/>
    <geom type="sphere" size="1" rgba="1 0 0 1"/>
  </worldbody>
</mujoco>

Code:

import mujoco
import mediapy as media
model = mujoco.MjModel.from_xml_string(xml)
data = mujoco.MjData(model)

with mujoco.Renderer(model) as renderer:
  mujoco.mj_forward(model, data)
  renderer.update_scene(data)

  media.show_image(renderer.render())

Confirmations

I searched the latest documentation thoroughly before posting.
I searched previous Issues and Discussions, I am certain this has not been raised before.

Balint-H · 2025-01-20T12:02:20Z

Balint-H
Jan 20, 2025
Collaborator

Hello,
Without a proper minimal example that reproduces the issue it is a bit tougher to figure out what is going on. In any case, there are a couple things you can check:

How stiff are your actuators? If they are more compliant, they can grasp objects better. Too stiff and the fingers try to penetrate the object with massive reaction forces leading to jittering.
Explore documentation on the solref and solimp fields using which you can make contacts softer and potentially more stable. Have you changed these settings already?
Check out the multiccd flag option, which can stabilise grasps
Usual parameters that influence simulation stability are also relevant: timestep, integrator, solver params

There are other further things to check, but this is a good start. Let me know whether this helps!

1 reply

gemcollector Jan 20, 2025
Author

Hi, thx for your quick reply! Here is my xml file:

<default>
    <default class="left_hand">
      <joint damping="0.05" armature="0.0002" frictionloss="0.01"/>
      <geom friction="1.5 0.1 0.1" condim="3" contype="1" conaffinity="1"/>
    </default>
    <default class="right_hand">
      <joint damping="0.05" armature="0.0002" frictionloss="0.01"/>
      <geom friction="1.5 0.1 0.1" condim="3" contype="1" conaffinity="1"/>
    </default>
    <default class="translation">
      <position kp="5000" dampratio="1" ctrlrange="-1 1"/>
    </default>
    <default class="rotation">
      <position kp="300" dampratio="1" ctrlrange="-1.571 1.571"/>
    </default>
  </default>

  <default>
    <default class="finger">
      <!-- <joint damping="0.03"/> -->
      <joint damping="1" frictionloss="0.05"/>
    </default>
    <default class="hand_col">
      <geom condim="3" contype="1" conaffinity="1" rgba="1 0 1 0" />
    </default>
    <default class="hand_visual">
      <geom contype="0" conaffinity="0"/>
    </default>
    <default class="thumb">
      <!-- <joint damping="0.05"/> -->
      <joint damping="1.5"/>
    </default>
  </default>

  <worldbody>
    <site name="world_reference" pos="0 0 0" euler="0 0 0" rgba="1 0 0 0"/>
    <site name="r_reference" pos="0.0171 -0.277 0.255" quat="-0.65318068 -0.58712507 -0.32543885 -0.35032656" rgba="1 0 0 1" size="0.01"/>
    <site name="l_reference" pos="0.00431 0.191 0.245" quat="-0.36096859 -0.37392054 -0.60766855 -0.6005198" rgba="1 0 0 1" size="0.01"/>
    <!-- <body>
      <geom type="box" pos="0 -0.15 0.1" size="0.1 0.1 0.1" rgba="1 0 0 1"/>
    </body> -->
    <body name="platform_link" pos="-0.9 -0.3 -0.72">
    <geom type="mesh" mesh="platform23" rgba="0.79216 0.81961 0.93333 1" group="1" contype="0" conaffinity="0"/>
    <geom type="mesh" mesh="platform-part-0" rgba="0.79216 0.81961 0.93333 1" group="5" contype="1" conaffinity="1"/>
    <geom type="mesh" mesh="platform-part-1" rgba="0.79216 0.81961 0.93333 1" group="5" contype="1" conaffinity="1"/>
    <geom type="mesh" mesh="platform-part-2" rgba="0.79216 0.81961 0.93333 1" group="5" contype="1" conaffinity="1"/>
    <body name='human_viewpoint' pos="1.05 0.25 0.97"/>
    <camera name="human_view" mode="targetbody" target="human_viewpoint" pos="0.33 0.25 1.3" fovy="63"/>
    <body name="r_arm_base_link" pos="0.25 0.045 1.092" euler="2.09 0 -1.57" gravcomp="1">
      <geom type="mesh" rgba="0.79216 0.81961 0.93333 1" mesh="base_link"/>
      <body name="r_arm_seg1" pos="-0.0011147 0 0.0892" quat="-3.67321e-06 0 0 1" gravcomp="1">
        <inertial pos="-1.4403e-06 -0.00074041 0.056573" quat="0.707084 0.00122867 -0.00107609 0.707127" mass="0.95" diaginertia="0.000708573 0.00058101 0.000445827"/>
        <joint name="r_arm_joint1" pos="0 0 0" axis="0 0 1" range="-2.8798 2.8798"/>
        <geom type="mesh" rgba="0.79216 0.81961 0.93333 1" mesh="arm_seg1"/>
        <body name="r_arm_seg2" pos="0 -4e-05 0.0615" quat="0.707105 0.707108 0 0" gravcomp="1">
          <inertial pos="0.23622 0.016356 9.154e-05" quat="0.484393 0.48518 0.524693 0.504639" mass="1" diaginertia="0.00761886 0.00757469 0.000578276"/>
          <joint name="r_arm_joint2" pos="0 0 0" axis="0 0 1" range="0.0 3.1415"/>
          <geom type="mesh" rgba="0.79216 0.81961 0.93333 1" mesh="arm_seg2"/>
          <body name="r_arm_seg3" pos="0.34928 0.02 0" quat="0.707105 0 0 0.707108" gravcomp="1">
            <inertial pos="0.054443 0.045347 0.00042807" quat="0.595278 0.471808 -0.522016 0.387995" mass="0.7" diaginertia="0.00149749 0.00144877 0.00053598"/>
            <joint name="r_arm_joint3" pos="0 0 0" axis="0 0 1" range="-3.3161 0"/>
            <geom type="mesh" rgba="0.79216 0.81961 0.93333 1" mesh="arm_seg3"/>
            <body name="r_arm_seg4" pos="0.07 -0.00395 -4e-05" quat="0.499998 -0.5 0.5 0.500002" gravcomp="1">
              <inertial pos="7.6256e-07 -0.0021448 0.27415" quat="0.70651 0.0169198 -0.0168252 0.707301" mass="0.4" diaginertia="0.000101779 9.7042e-05 8.44616e-05"/>
              <joint name="r_arm_joint4" pos="0 0 0" axis="0 0 1" range="-2.8798 2.8798"/>
              <geom type="mesh" rgba="1 1 1 1" mesh="arm_seg4"/>
              <body name="r_arm_seg5" pos="0 0 0.2776" quat="-2.59734e-06 2.59735e-06 -0.707108 0.707105" gravcomp="1">
                <inertial pos="-3.9997e-06 -0.05431 0.0034482" quat="0.477398 0.87868 0.00338218 -0.000840949" mass="0.3" diaginertia="0.00011332 0.000109027 7.34689e-05"/>
                <joint name="r_arm_joint5" pos="0 0 0" axis="0 0 1" range="-1.6581 1.6581"/>
                <geom type="mesh" rgba="1 1 1 1" mesh="arm_seg5"/>
                <body name="r_arm_seg6" pos="0 -0.1575 -0.00023266" quat="0.707105 0.707108 0 0" gravcomp="1">
                  <inertial pos="2.406e-06 -9.4582e-08 -0.038796" quat="1 -8.0778e-06 -0.000185306 8.09142e-05" mass="0.35" diaginertia="0.00011445 0.00011239 7.4519e-05"/>
                  <joint name="r_arm_joint6" pos="0 0 0" axis="0 0 1" range="-2.8798 2.8798"/>
                  <geom type="mesh" rgba="0.79216 0.81961 0.93333 1" mesh="arm_seg6"/>
                  <site name="r_end_effector" pos="0 0 0"/>               
                  <body name="oymotion_r_hand" euler="-1.57 0 -1.57" gravcomp="1" childclass="right_hand">
                    <body name="r_base" gravcomp="1">
                      <site name="r_tcp_site" pos="0.11 0 -0.04" size="0.01" rgba="0 0 1 1"/>
                      <geom type="mesh" rgba="0.776471 0.756863 0.737255 1" mesh="r_oymotion_base_link" class="hand_visual"/>
                      <geom type="box" pos="0.07 0 -0.0055" size="0.045 0.04 0.01" euler="0 -0.15 0" class="hand_col"/>
                      <geom type="box" pos="0.07 0 0.008" size="0.045 0.04 0.012" euler="0 0.04 0" class="hand_col"/>
                      <site pos="0 0 0.075" size="0.003 0.003 0.1" type="box" name="eef_r_mc_1" rgba="0 0 1 1" group="2"/>
                      <site pos="0 0.075 0" size="0.003 0.1 0.003" type="box" name="eef_r_mc_2" rgba="0 1 0 1" group="2"/>
                      <site pos="0.075 0 0" size="0.1 0.003 0.003" type="box" name="eef_r_mc_3" rgba="1 0 0 1" group="2"/>
                    </body>
                    <body name="r_th1" pos="0.0490826 0.0198778 -0.0230224" quat="0.994021 0.000704684 0.108993 0.00642674" gravcomp="1">
                      <inertial pos="0.00191984 0.00319719 -0.00597433" quat="-0.195508 0.354122 0.316551 -0.858004" mass="0.017482" diaginertia="2.15824e-06 1.78948e-06 8.42171e-07"/>
                      <joint name="r_th1" pos="0 0 0" axis="-1 0 0" range="0 1.57" class="thumb" ref="0.7"/>
                      <geom type="mesh" rgba="0.776471 0.756863 0.737255 1" mesh="r_th1"  class="hand_visual"/>
                      <body name="r_th2" pos="0.0150163 0.00377111 -0.0184123" quat="0.655201 -0.265917 -0.659812 0.254261" gravcomp="1">
                        <inertial pos="-0.00809998 0.00382843 -0.00282376" quat="0.892632 0.450786 0 0" mass="0.000789049" diaginertia="1.19393e-08 1.07536e-08 1.35034e-09"/>
                        <joint name="r_th2" pos="0 0 0" axis="-1 0 0" range="0.0 1.0" class="thumb" ref="0.75"/>
                        <geom type="mesh" rgba="0.776471 0.756863 0.737255 1" mesh="r_th2" class="hand_visual"/>
                        <body name="r_th2_1" pos="0 0.00883641 -0.00651754" gravcomp="1">
                          <inertial pos="-0.00804903 0.00193436 -0.00890089" quat="0.702987 0.0761563 0.0761476 -0.703002" mass="0.00752752" diaginertia="6.05507e-07 4.65637e-07 1.9027e-07"/>
                          <joint name="r_th2_1" pos="0 0 0" axis="-1 0 0" class="thumb"/>
                          <geom type="mesh" rgba="0.776471 0.756863 0.737255 1" mesh="r_th2_1" class="hand_visual"/>
                          <body name="r_th2_2" pos="0.00440345 0.0076881 -0.0314156" quat="0.803914 0.594745 0 0" gravcomp="1">
                            <inertial pos="-0.00373227 -0.00464828 -0.00091513" quat="0.467303 0.530686 0.530686 -0.467303" mass="0.00261208" diaginertia="4.35995e-08 3.91261e-08 1.67325e-08"/>
                            <joint name="r_th2_2" pos="0 0 0" axis="-1 0 0" class="thumb"/>
                            <geom type="mesh" rgba="0.776471 0.756863 0.737255 1" mesh="r_th2_2" class="hand_visual"/>
                            <body name="r_th2_3" pos="-0.00295 -0.00981212 -0.00131618" gravcomp="1">
                              <inertial pos="-0.00665584 -0.0101877 0.00658848" quat="0.453258 0.54272 0.542731 -0.453272" mass="0.0392776" diaginertia="2.36983e-06 1.85862e-06 1.2918e-06"/>
                              <joint name="r_th2_3" pos="0 0 0" axis="-1 0 0" class="thumb"/>
                              <geom type="mesh" rgba="0.776471 0.756863 0.737255 1" mesh="r_th2_3" class="hand_visual"/>
                              <geom type="capsule" pos="0.007 -0.011 0.007" size="0.009 0.009" euler="1.6 0 0" class="hand_col"/>
                            </body>
                          </body>
                          <body name="r_th2_slide" pos="0.00394993 0.000195499 0.0109735" quat="0.678228 -0.200017 -0.628683 -0.323663" gravcomp="1">
                            <inertial pos="0.0113547 -0.000312971 -0.00565436" quat="-0.175069 0.696448 0.301544 -0.627202" mass="0.0704476" diaginertia="2.20935e-05 2.05412e-05 6.20846e-06"/>
                            <joint name="r_th2_slide" pos="0 0 0" axis="-1 0 0" type="slide" damping="0.5"/>
                            <geom type="mesh" rgba="0.776471 0.756863 0.737255 1" mesh="r_th2_slide"  class="hand_visual"/>
                            <geom type="capsule" pos="-0.012 -0.002 -0.008" size="0.013 0.020" euler="0.8 1.57 0" class="hand_col"/>
                          </body>
                        </body>
                      </body>
                    </body>
                    <body name="r_ff1" pos="0.115122 0.0375536 0.0020566" quat="0.295459 0.609378 0.687604 0.261846" gravcomp="1">
                      <inertial pos="0.0070298 0.00894962 0.0163319" quat="0.662849 -0.246153 -0.246091 -0.662933" mass="0.0152443" diaginertia="1.5138e-06 1.35281e-06 5.40981e-07"/>
                      <joint name="r_ff1" pos="0 0 0" axis="-1 0 0" range="1.75 3.11" class="finger" ref="3.02"/>
                      <geom type="mesh" rgba="0.776471 0.756863 0.737255 1" mesh="r_ff1" class="hand_visual"/>
                      <geom type="capsule" pos="-0.007 0.01 0.02" size="0.0075 0.014" euler="-0.7 0 0" class="hand_col"/>
                      <body name="r_ff1_1" pos="0 0.021096 0.029073" gravcomp="1">
                        <inertial pos="0.00697876 0.0067486 0.0235874" quat="0.700497 -0.0949982 -0.0951152 -0.70088" mass="0.0342358" diaginertia="5.2505e-06 5.24298e-06 5.95152e-07"/>
                        <joint name="r_ff1_1" pos="0 0 0" axis="-1 0 0" class="finger"/>
                        <geom type="mesh" rgba="0.776471 0.756863 0.737255 1" mesh="r_ff1_1" class="hand_visual"/>
                        <geom type="capsule" pos="-0.007 0.008 0.028" size="0.0065 0.016" euler="-0.3 0 0" class="hand_col"/>
                      </body>
                    </body>
                    <body name="r_base_to_ff" pos="0.122756 0.0353019 0.0067253" quat="0.295636 0.609335 0.687498 0.262025" gravcomp="1">
                      <inertial pos="0.00370009 0.00341586 0.0165511" quat="0.701491 -0.0889417 -0.0889417 -0.701491" mass="0.00267235" diaginertia="4.96063e-07 4.86522e-07 1.90482e-08"/>
                      <joint name="r_base_to_ff" pos="0 0 0" axis="-1 0 0"/>
                      <geom type="mesh" rgba="0.776471 0.756863 0.737255 1" mesh="r_base_to_ff"  class="hand_visual"/>
                    </body>
                    <body name="r_mf1" pos="0.11888 0.01765 0.0069653" quat="0.00334089 0.702842 0.71133 0.00330105" gravcomp="1">
                      <inertial pos="0.0070074 0.0203658 0.00677331" quat="0.466516 0.531416 0.531075 -0.466818" mass="0.0182531" diaginertia="2.54837e-06 2.38777e-06 6.77106e-07"/>
                      <joint name="r_mf1" pos="0 0 0" axis="-1 0 0" range="1.71 3.07" class="finger" ref="3.0"/>
                      <geom type="mesh" rgba="0.776471 0.756863 0.737255 1" mesh="r_mf1" class="hand_visual"/>
                      <geom type="capsule" pos="-0.007 0.02 0.008" size="0.0075 0.014" euler="-1.5 0 0" class="hand_col"/>
                      <body name="r_mf1_1" pos="0 0.040241 0.0078924" gravcomp="1">
                        <inertial pos="0.00693657 0.0214322 0.0119471" quat="0.355221 0.611869 0.610762 -0.355534" mass="0.0342357" diaginertia="5.2505e-06 5.24298e-06 5.95151e-07"/>
                        <joint name="r_mf1_1" pos="0 0 0" axis="-1 0 0" class="finger"/>
                        <geom type="mesh" rgba="0.776471 0.756863 0.737255 1" mesh="r_mf1_1" class="hand_visual"/>
                        <geom type="capsule" pos="-0.007 0.025 0.015" size="0.0065 0.016" euler="-1.1 0 0" class="hand_col"/>
                      </body>
                    </body>
                    <body name="r_base_to_mf" pos="0.126338 0.0144304 0.0113662" quat="0.000565756 -0.702408 -0.711774 0.000558312" gravcomp="1">
                      <inertial pos="0.00370005 0.0163936 0.0102722" quat="0.357408 0.610131 0.610131 -0.357408" mass="0.00285033" diaginertia="6.82745e-07 6.72641e-07 2.02362e-08"/>
                      <joint name="r_base_to_mf" pos="0 0 0" axis="-1 0 0"/>
                      <geom type="mesh" rgba="0.776471 0.756863 0.737255 1" mesh="r_base_to_mf" class="hand_visual"/>
                    </body>
                    <body name="r_rf1" pos="0.11663 -0.002443 0.0062162" quat="0.726796 -4.00974e-05 -3.78937e-05 0.686853" gravcomp="1">
                      <inertial pos="0.00704135 -0.0178884 -0.0046376" quat="0.483953 0.515519 0.515557 -0.483973" mass="0.0151473" diaginertia="1.51374e-06 1.35267e-06 5.40891e-07"/>
                      <joint name="r_rf1" pos="0 0 0" axis="-1 0 0" range="1.77 3.08" class="finger" ref="3.0"/>
                      <geom type="mesh" rgba="0.776471 0.756863 0.737255 1" mesh="r_rf1" class="hand_visual"/>
                      <geom type="capsule" pos="-0.007 -0.02 -0.006" size="0.0075 0.013" euler="-1.55 0 0" class="hand_col"/>
                      <body name="r_rf1_1" pos="0 -0.035592 -0.0048427" gravcomp="1">
                        <inertial pos="0.00697877 -0.0217085 -0.0114017" quat="0.3627 0.606553 0.607179 -0.363148" mass="0.0342355" diaginertia="5.25042e-06 5.2429e-06 5.95154e-07"/>
                        <joint name="r_rf1_1" pos="0 0 0" axis="-1 0 0" class="finger"/>
                        <geom type="mesh" rgba="0.776471 0.756863 0.737255 1" mesh="r_rf1_1" class="hand_visual"/>
                        <geom type="capsule" pos="-0.007 -0.025 -0.014" size="0.0065 0.017" euler="-1.1 0 0" class="hand_col"/>
                      </body>
                    </body>
                    <body name="r_base_to_rf" pos="0.123853 -0.00613089 0.0106155" quat="0.726833 -0.0001276 -0.000135035 0.686814" gravcomp="1">
                      <inertial pos="0.00370009 -0.0143262 -0.00896467" quat="0.357577 0.610032 0.610032 -0.357577" mass="0.00267235" diaginertia="4.96063e-07 4.86522e-07 1.90482e-08"/>
                      <joint name="r_base_to_rf" pos="0 0 0" axis="-1 0 0"/>
                      <geom type="mesh" rgba="0.776471 0.756863 0.737255 1" mesh="r_base_to_rf" class="hand_visual"/>
                    </body>
                    <body name="r_lf1" pos="0.11331 -0.022575 0.0042735" quat="0.719041 -0.204609 -0.237125 0.620393" gravcomp="1">
                      <inertial pos="0.00699992 -0.0101266 -0.01254" quat="0.289166 0.645275 0.645279 -0.289168" mass="0.0142656" diaginertia="1.53678e-06 1.36656e-06 5.17078e-07"/>
                      <joint name="r_lf1" pos="0 0 0" axis="-1 0 0" range="1.73 3.05" class="finger" ref="3.0"/>
                      <geom type="mesh" rgba="0.776471 0.756863 0.737255 1" mesh="r_lf1" class="hand_visual"/>
                      <geom type="capsule" pos="-0.007 -0.012 -0.014" size="0.0075 0.009" euler="-0.9 0 0" class="hand_col"/>
                      <body name="r_lf1_1" pos="0 -0.022718 -0.022439" gravcomp="1">
                        <inertial pos="0.00705269 -0.00763281 -0.0155353" quat="0.690987 -0.150197 -0.15019 -0.690956" mass="0.0202843" diaginertia="1.52435e-06 1.4952e-06 3.06212e-07"/>
                        <joint name="r_lf1_1" pos="0 0 0" axis="-1 0 0" class="finger"/>
                        <geom type="mesh" rgba="0.776471 0.756863 0.737255 1" mesh="r_lf1_1" class="hand_visual"/>
                        <geom type="cylinder" pos="-0.007 -0.009 -0.018" size="0.0065 0.014" euler="-0.45 0 0" class="hand_col"/>
                      </body>
                    </body>
                    <body name="r_base_to_lf" pos="0.12024 -0.027096 0.0083686" quat="0.719041 -0.204609 -0.237125 0.620393" gravcomp="1">
                      <inertial pos="0.00370001 -0.00492796 -0.0142868" quat="0.694427 -0.13331 -0.13331 -0.694427" mass="0.00247299" diaginertia="3.87303e-07 3.78315e-07 1.76363e-08"/>
                      <joint name="r_base_to_lf" pos="0 0 0" axis="-1 0 0"/>
                      <geom type="mesh" rgba="0.776471 0.756863 0.737255 1" mesh="r_base_to_lf"/>
                    </body>
                  </body>
                </body>
              </body>
            </body>
          </body>
        </body>
      </body>
    </body>

    <!-- 0.1 0.18 1.2 -->
    <body name="l_arm_base_link" pos="0.25 0.553 1.092" euler="-2.09 0 1.57" gravcomp="1">
      <geom type="mesh" rgba="0.79216 0.81961 0.93333 1" mesh="base_link"/>
      <body name="l_arm_seg1" pos="-0.0011147 0 0.0892" quat="-3.67321e-06 0 0 1" gravcomp="1">
        <inertial pos="-1.4403e-06 -0.00074041 0.056573" quat="0.707084 0.00122867 -0.00107609 0.707127" mass="0.95" diaginertia="0.000708573 0.00058101 0.000445827"/>
        <joint name="l_arm_joint1" pos="0 0 0" axis="0 0 1" range="-2.8798 2.8798"/>
        <geom type="mesh" rgba="0.79216 0.81961 0.93333 1" mesh="arm_seg1"/>
        <body name="l_arm_seg2" pos="0 -4e-05 0.0615" quat="0.707105 0.707108 0 0" gravcomp="1">
          <inertial pos="0.23622 0.016356 9.154e-05" quat="0.484393 0.48518 0.524693 0.504639" mass="1" diaginertia="0.00761886 0.00757469 0.000578276"/>
          <joint name="l_arm_joint2" pos="0 0 0" axis="0 0 1" range="0.0 3.1415"/>
          <geom type="mesh" rgba="0.79216 0.81961 0.93333 1" mesh="arm_seg2"/>
          <body name="l_arm_seg3" pos="0.34928 0.02 0" quat="0.707105 0 0 0.707108" gravcomp="1">
            <inertial pos="0.054443 0.045347 0.00042807" quat="0.595278 0.471808 -0.522016 0.387995" mass="0.7" diaginertia="0.00149749 0.00144877 0.00053598"/>
            <joint name="l_arm_joint3" pos="0 0 0" axis="0 0 1" range="-3.3161 0"/>
            <geom type="mesh" rgba="0.79216 0.81961 0.93333 1" mesh="arm_seg3"/>
            <body name="l_arm_seg4" pos="0.07 -0.00395 -4e-05" quat="0.499998 -0.5 0.5 0.500002" gravcomp="1">
              <inertial pos="7.6256e-07 -0.0021448 0.27415" quat="0.70651 0.0169198 -0.0168252 0.707301" mass="0.4" diaginertia="0.000101779 9.7042e-05 8.44616e-05"/>
              <joint name="l_arm_joint4" pos="0 0 0" axis="0 0 1" range="-2.8798 2.8798"/>
              <geom type="mesh" rgba="1 1 1 1" mesh="arm_seg4"/>
              <body name="l_arm_seg5" pos="0 0 0.2776" quat="-2.59734e-06 2.59735e-06 -0.707108 0.707105" gravcomp="1">
                <inertial pos="-3.9997e-06 -0.05431 0.0034482" quat="0.477398 0.87868 0.00338218 -0.000840949" mass="0.3" diaginertia="0.00011332 0.000109027 7.34689e-05"/>
                <joint name="l_arm_joint5" pos="0 0 0" axis="0 0 1" range="-1.6581 1.6581"/>
                <geom type="mesh" rgba="1 1 1 1" mesh="arm_seg5"/>
                <body name="l_arm_seg6" pos="0 -0.1575 -0.00023266" quat="0.707105 0.707108 0 0" gravcomp="1">
                  <inertial pos="2.406e-06 -9.4582e-08 -0.038796" quat="1 -8.0778e-06 -0.000185306 8.09142e-05" mass="0.35" diaginertia="0.00011445 0.00011239 7.4519e-05"/>
                  <joint name="l_arm_joint6" pos="0 0 0" axis="0 0 1" range="-2.8798 2.8798"/>
                  <geom type="mesh" rgba="0.79216 0.81961 0.93333 1" mesh="arm_seg6"/>
                  <site name="l_end_effector" pos="0 0 0"/> 
                  <body name="oymotion_left_hand" pos="0.0 0.0 0.0" euler="-1.57 0 1.57" gravcomp="1">
                    <body name="l_base" gravcomp="1">
                      <site name="l_tcp_site" pos="-0.11 0 -0.04" size="0.01" rgba="0 0 1 1"/>
                      <geom type="mesh" rgba="0.776471 0.756863 0.737255 1" mesh="l_oymotion_base_link"/>
                    </body>
                    <body name="l_th1" pos="-0.049083 0.019878 -0.023022" quat="0.994021 0.000704702 -0.108995 -0.0064266" gravcomp="1">
                      <inertial pos="0.00191984 0.00319719 -0.00597433" quat="-0.195508 0.354122 -0.316551 0.858004" mass="0.017482" diaginertia="2.15824e-06 1.78948e-06 8.42171e-07"/>
                      <joint name="l_th1" pos="0 0 0" axis="-1 0 0" range="0 1.57" class="thumb" ref="0.7"/>
                      <geom type="mesh" rgba="0.776471 0.756863 0.737255 1" mesh="l_th1"/>
                      <body name="l_th2" pos="-0.015016 0.0037711 -0.018412" quat="0.655204 -0.265906 0.65981 -0.254268" gravcomp="1">
                        <inertial pos="-0.00809998 0.00382843 -0.00282376" quat="0.892632 0.450786 0 0" mass="0.000789049" diaginertia="1.19393e-08 1.07536e-08 1.35034e-09"/>
                        <joint name="l_th2" pos="0 0 0" axis="-1 0 0" range="0.0 1.0" class="thumb" ref="0.75"/>
                        <geom type="mesh" rgba="0.776471 0.756863 0.737255 1" mesh="l_th2"/>
                        <body name="l_th2_1" pos="0 0.0088364 -0.0065175" gravcomp="1">
                          <inertial pos="-0.00804903 0.00193436 -0.00890089" quat="0.702987 0.0761563 -0.0761476 0.703002" mass="0.00752752" diaginertia="6.05507e-07 4.65637e-07 1.9027e-07"/>
                          <joint name="l_th2_1" pos="0 0 0" axis="-1 0 0" class="thumb"/>
                          <geom type="mesh" rgba="0.776471 0.756863 0.737255 1" mesh="l_th2_1"/>
                          <body name="l_th2_2" pos="-0.00440345 0.0076881 -0.0314156" quat="0.803914 0.594745 0 0" gravcomp="1">
                            <inertial pos="-0.00373227 -0.00464828 -0.00091513" quat="0.467303 0.530686 -0.530686 0.467303" mass="0.00261208" diaginertia="4.35995e-08 3.91261e-08 1.67325e-08"/>
                            <joint name="l_th2_2" pos="0 0 0" axis="-1 0 0" class="thumb"/>
                            <geom type="mesh" rgba="0.776471 0.756863 0.737255 1" mesh="l_th2_2"/>
                            <body name="l_th2_3" pos="0.00295 -0.00981212 -0.00131618" gravcomp="1">
                              <inertial pos="-0.00665584 -0.0101877 0.00658848" quat="0.453258 0.54272 -0.542731 0.453272" mass="0.0392776" diaginertia="2.36983e-06 1.85862e-06 1.2918e-06"/>
                              <joint name="l_th2_3" pos="0 0 0" axis="-1 0 0" class="thumb"/>
                              <geom type="mesh" rgba="0.776471 0.756863 0.737255 1" mesh="l_th2_3" class="hand_visual"/>
                              <geom type="cylinder" pos="-0.007 -0.011 0.006" size="0.0095 0.013" euler="1.7 0 0" class="hand_col"/>
                            </body>
                          </body>
                          <body name="l_th2_slide" pos="-0.00394993 0.000195499 0.0109735" quat="0.678228 -0.200017 0.628683 0.323663" gravcomp="1">
                            <inertial pos="0.0113547 -0.000312971 -0.00565436" quat="-0.175069 0.696448 -0.301544 0.627202" mass="0.0704476" diaginertia="2.20935e-05 2.05412e-05 6.20846e-06"/>
                            <joint name="l_th2_slide" pos="0 0 0" axis="-1 0 0" type="slide" damping="0.5"/>
                            <geom type="mesh" rgba="0.776471 0.756863 0.737255 1" mesh="l_th2_slide"/>
                          </body>
                        </body>
                      </body>
                    </body>
                    <body name="l_ff1" pos="-0.11512 0.037554 0.0020566" quat="0.295478 0.609382 -0.687588 -0.261857" gravcomp="1">
                      <inertial pos="0.0070298 0.00894962 0.0163319" quat="0.662849 -0.246153 0.246091 0.662933" mass="0.0152443" diaginertia="1.5138e-06 1.35281e-06 5.40981e-07"/>
                      <joint name="l_ff1" pos="0 0 0" axis="-1 0 0" range="1.75 3.11" class="finger" ref="3.02"/>
                      <geom type="mesh" rgba="0.776471 0.756863 0.737255 1" mesh="l_ff1"/>
                      <body name="l_ff1_1" pos="0 0.021096 0.029073" gravcomp="1">
                        <inertial pos="0.00697876 0.0067486 0.0235874" quat="0.700497 -0.0949982 0.0951152 0.70088" mass="0.0342358" diaginertia="5.2505e-06 5.24298e-06 5.95152e-07"/>
                        <joint name="l_ff1_1" pos="0 0 0" axis="-1 0 0" class="finger"/>
                        <geom type="mesh" rgba="0.776471 0.756863 0.737255 1" mesh="l_ff1_1" class="hand_visual"/>
                        <geom type="cylinder" pos="0.007 0.008 0.028" size="0.007 0.02" euler="-0.3 0 0" class="hand_col"/>
                      </body>
                    </body>
                    <body name="l_base_to_ff" pos="-0.12276 0.035302 0.0067253" quat="0.295638 0.609345 -0.68749 -0.262019" gravcomp="1">
                      <inertial pos="0.00370009 0.00341586 0.0165511" quat="0.701491 -0.0889417 0.0889417 0.701491" mass="0.00267235" diaginertia="4.96063e-07 4.86522e-07 1.90482e-08"/>
                      <joint name="l_base_to_ff" pos="0 0 0" axis="-1 0 0"/>
                      <geom type="mesh" rgba="0.776471 0.756863 0.737255 1" mesh="l_base_to_ff"/>
                    </body>
                    <body name="l_mf1" pos="-0.11888 0.01765 0.0069653" quat="0.00334089 0.702842 -0.71133 -0.00330105" gravcomp="1">
                      <inertial pos="0.0070074 0.0203658 0.00677331" quat="0.466516 0.531416 -0.531075 0.466818" mass="0.0182531" diaginertia="2.54837e-06 2.38777e-06 6.77106e-07"/>
                      <joint name="l_mf1" pos="0 0 0" axis="-1 0 0" range="1.71 3.07" class="finger" ref="3.0"/>
                      <geom type="mesh" rgba="0.776471 0.756863 0.737255 1" mesh="l_mf1"/>
                      <body name="l_mf1_1" pos="0 0.0402408 0.00789236" gravcomp="1">
                        <inertial pos="0.00693657 0.0214322 0.0119471" quat="0.355221 0.611869 -0.610762 0.355534" mass="0.0342357" diaginertia="5.2505e-06 5.24298e-06 5.95151e-07"/>
                        <joint name="l_mf1_1" pos="0 0 0" axis="-1 0 0" class="finger"/>
                        <geom type="mesh" rgba="0.776471 0.756863 0.737255 1" mesh="l_mf1_1" class="hand_visual"/>
                        <geom type="cylinder" pos="0.007 0.025 0.015" size="0.007 0.02" euler="-1.1 0 0" class="hand_col"/>
                      </body>
                    </body>
                    <body name="l_base_to_mf" pos="-0.12634 0.01443 0.011366" quat="0.000566851 -0.702423 0.711759 -0.000559398" gravcomp="1">
                      <inertial pos="0.00370005 0.0163936 0.0102722" quat="0.357408 0.610131 -0.610131 0.357408" mass="0.00285033" diaginertia="6.82745e-07 6.72641e-07 2.02362e-08"/>
                      <joint name="l_base_to_mf" pos="0 0 0" axis="-1 0 0"/>
                      <geom type="mesh" rgba="0.776471 0.756863 0.737255 1" mesh="l_base_to_mf"/>
                    </body>
                    <body name="l_rf1" pos="-0.11663 -0.002443 0.0062162" quat="0.726796 -4.00974e-05 3.78937e-05 -0.686853" gravcomp="1">
                      <inertial pos="0.00704135 -0.0178884 -0.0046376" quat="0.483953 0.515519 -0.515557 0.483973" mass="0.0151473" diaginertia="1.51374e-06 1.35267e-06 5.40891e-07"/>
                      <joint name="l_rf1" pos="0 0 0" axis="-1 0 0" range="1.77 3.08" class="finger" ref="3.0"/>
                      <geom type="mesh" rgba="0.776471 0.756863 0.737255 1" mesh="l_rf1"/>
                      <body name="l_rf1_1" pos="0 -0.035592 -0.0048427" gravcomp="1">
                        <inertial pos="0.00697877 -0.0217085 -0.0114017" quat="0.3627 0.606553 -0.607179 0.363148" mass="0.0342355" diaginertia="5.25042e-06 5.2429e-06 5.95154e-07"/>
                        <joint name="l_rf1_1" pos="0 0 0" axis="-0.997657 0.0684163 0.000525256" class="finger"/>
                        <geom type="mesh" rgba="0.776471 0.756863 0.737255 1" mesh="l_rf1_1" class="hand_visual"/>
                        <geom type="cylinder" pos="0.007 -0.025 -0.014" size="0.007 0.02" euler="-1.1 0 0" class="hand_col"/>
                      </body>
                    </body>
                    <body name="l_base_to_rf" pos="-0.12385 -0.0061309 0.010616" quat="0.726831 -0.000127601 0.000135037 -0.686817" gravcomp="1">
                      <inertial pos="0.00370009 -0.0143262 -0.00896467" quat="0.357577 0.610032 -0.610032 0.357577" mass="0.00267235" diaginertia="4.96063e-07 4.86522e-07 1.90482e-08"/>
                      <joint name="l_base_to_rf" pos="0 0 0" axis="-1 0 0"/>
                      <geom type="mesh" rgba="0.776471 0.756863 0.737255 1" mesh="l_base_to_rf"/>
                    </body>
                    <body name="l_lf1" pos="-0.11331 -0.022575 0.0042735" quat="0.719041 -0.204609 0.237125 -0.620393" gravcomp="1">
                      <inertial pos="0.00699992 -0.0101266 -0.01254" quat="0.289166 0.645275 -0.645279 0.289168" mass="0.0142656" diaginertia="1.53678e-06 1.36656e-06 5.17078e-07"/>
                      <joint name="l_lf1" pos="0 0 0" axis="-1 0 0" range="1.73 3.05" class="finger" ref="3.0"/>
                      <geom type="mesh" rgba="0.776471 0.756863 0.737255 1" mesh="l_lf1"/>
                      <body name="l_lf1_1" pos="0 -0.0227178 -0.0224385" gravcomp="1">
                        <inertial pos="0.00705269 -0.00763281 -0.0155353" quat="0.690987 -0.150197 0.15019 0.690956" mass="0.0202843" diaginertia="1.52435e-06 1.4952e-06 3.06212e-07"/>
                        <joint name="l_lf1_1" pos="0 0 0" axis="-1 0 0" class="finger"/>
                        <geom type="mesh" rgba="0.776471 0.756863 0.737255 1" mesh="l_lf1_1" class="hand_visual"/>
                        <geom type="cylinder" pos="0.007 -0.009 -0.018" size="0.0065 0.014" euler="-0.45 0 0" class="hand_col"/>
                      </body>
                    </body>
                    <body name="l_base_to_lf" pos="-0.120243 -0.0270965 0.0083686" quat="0.719028 -0.204605 0.23713 -0.620407" gravcomp="1">
                      <inertial pos="0.00370001 -0.00492796 -0.0142868" quat="0.694427 -0.13331 0.13331 0.694427" mass="0.00247299" diaginertia="3.87303e-07 3.78315e-07 1.76363e-08"/>
                      <joint name="l_base_to_lf" pos="0 0 0" axis="-1 0 0"/>
                      <geom type="mesh" rgba="0.776471 0.756863 0.737255 1" mesh="l_base_to_lf"/>
                    </body>
                   </body> 
                </body>
              </body>
            </body>
          </body>
        </body>
      </body>
    </body>
    </body>
  </worldbody>

  <contact>
    <!-- <exclude body1="arm_seg3" body2="arm_seg4"/>
    <exclude body1="arm_seg2" body2="arm_seg3"/> -->
    <exclude body1="platform_link" body2="r_arm_base_link"/>
    <exclude body1="platform_link" body2="r_arm_seg1"/>
    <exclude body1="platform_link" body2="r_arm_seg2"/>
    <exclude body1="platform_link" body2="r_arm_seg3"/>
    <exclude body1="r_arm_base_link" body2="r_arm_seg1"/>
    <exclude body1="r_arm_base_link" body2="r_arm_seg2"/>
    <exclude body1="r_arm_seg1" body2="r_arm_seg2"/>
    <exclude body1="r_arm_seg2" body2="r_arm_seg3"/>
    <exclude body1="r_arm_seg1" body2="r_arm_seg3"/>
    <exclude body1="r_base" body2="r_ff1"/>
    <exclude body1="r_base" body2="r_ff1_1"/>
    <exclude body1="r_base" body2="r_base_to_ff"/>
    <exclude body1="r_base_to_ff" body2="r_ff1"/>
    <exclude body1="r_base_to_ff" body2="r_ff1_1"/>
    <exclude body1="r_ff1" body2="r_ff1_1"/>

    <exclude body1="r_base" body2="r_mf1"/>
    <exclude body1="r_base" body2="r_mf1_1"/>
    <exclude body1="r_base" body2="r_base_to_mf"/>
    <exclude body1="r_base_to_mf" body2="r_mf1"/>
    <exclude body1="r_base_to_mf" body2="r_mf1_1"/>
    <exclude body1="r_mf1" body2="r_mf1_1"/>

    <exclude body1="r_base" body2="r_rf1"/>
    <exclude body1="r_base" body2="r_rf1_1"/>
    <exclude body1="r_base" body2="r_base_to_rf"/>
    <exclude body1="r_base_to_rf" body2="r_rf1"/>
    <exclude body1="r_base_to_rf" body2="r_rf1_1"/>
    <exclude body1="r_rf1" body2="r_rf1_1"/>
    
    <exclude body1="r_base" body2="r_lf1"/>
    <exclude body1="r_base" body2="r_base_to_lf"/>
    <exclude body1="r_lf1" body2="r_lf1_1"/>
    <exclude body1="r_base_to_lf" body2="r_lf1"/>
    <exclude body1="r_base_to_lf" body2="r_lf1_1"/>
    <exclude body1="r_base" body2="r_th1"/>

    <exclude body1="r_th1" body2="r_base"/>
    <exclude body1="r_th1" body2="r_th2"/>
    <exclude body1="r_th1" body2="r_th2_1"/>
    <exclude body1="r_th1" body2="r_th2_2"/>
    <exclude body1="r_th1" body2="r_th2_3"/>
    <exclude body1="r_th1" body2="r_th2_slide"/>

    <exclude body1="r_th2" body2="r_base"/>
    <exclude body1="r_th2" body2="r_th2_1"/>
    <exclude body1="r_th2" body2="r_th2_2"/>
    <exclude body1="r_th2" body2="r_th2_3"/>
    <exclude body1="r_th2" body2="r_th2_slide"/>
    
    <exclude body1="r_th2_1" body2="r_base"/>
    <exclude body1="r_th2_1" body2="r_th2_2"/>
    <exclude body1="r_th2_1" body2="r_th2_3"/>
    <exclude body1="r_th2_1" body2="r_th2_slide"/>

    <exclude body1="r_th2_2" body2="r_base"/>
    <exclude body1="r_th2_2" body2="r_th2_3"/>
    <exclude body1="r_th2_2" body2="r_th2_slide"/>
    
    <exclude body1="r_th2_3" body2="r_base"/>
    <exclude body1="r_th2_3" body2="r_th2_slide"/>

    <exclude body1="r_th2_slide" body2="r_base"/>

    <exclude body1="l_arm_base_link" body2="l_arm_seg1"/>
    <exclude body1="l_arm_base_link" body2="l_arm_seg2"/>
    <exclude body1="l_arm_seg1" body2="l_arm_seg2"/>
    <exclude body1="l_arm_seg2" body2="l_arm_seg3"/>
    <exclude body1="l_arm_seg1" body2="l_arm_seg3"/>
    <exclude body1="l_base" body2="l_ff1"/>
    <exclude body1="l_base" body2="l_ff1_1"/>
    <exclude body1="l_base" body2="l_base_to_ff"/>
    <exclude body1="l_base_to_ff" body2="l_ff1"/>
    <exclude body1="l_base_to_ff" body2="l_ff1_1"/>
    <exclude body1="l_ff1" body2="l_ff1_1"/>

    <exclude body1="l_base" body2="l_mf1"/>
    <exclude body1="l_base" body2="l_mf1_1"/>
    <exclude body1="l_base" body2="l_base_to_mf"/>
    <exclude body1="l_base_to_mf" body2="l_mf1"/>
    <exclude body1="l_base_to_mf" body2="l_mf1_1"/>
    <exclude body1="l_mf1" body2="l_mf1_1"/>

    <exclude body1="l_base" body2="l_rf1"/>
    <exclude body1="l_base" body2="l_rf1_1"/>
    <exclude body1="l_base" body2="l_base_to_rf"/>
    <exclude body1="l_base_to_rf" body2="l_rf1"/>
    <exclude body1="l_base_to_rf" body2="l_rf1_1"/>
    <exclude body1="l_rf1" body2="l_rf1_1"/>
    
    <exclude body1="l_base" body2="l_lf1"/>
    <exclude body1="l_base" body2="l_base_to_lf"/>
    <exclude body1="l_lf1" body2="l_lf1_1"/>
    <exclude body1="l_base_to_lf" body2="l_lf1"/>
    <exclude body1="l_base_to_lf" body2="l_lf1_1"/>
    <exclude body1="l_base" body2="l_th1"/>

    <exclude body1="l_th1" body2="l_base"/>
    <exclude body1="l_th1" body2="l_th2"/>
    <exclude body1="l_th1" body2="l_th2_1"/>
    <exclude body1="l_th1" body2="l_th2_2"/>
    <exclude body1="l_th1" body2="l_th2_3"/>
    <exclude body1="l_th1" body2="l_th2_slide"/>

    <exclude body1="l_th2" body2="l_base"/>
    <exclude body1="l_th2" body2="l_th2_1"/>
    <exclude body1="l_th2" body2="l_th2_2"/>
    <exclude body1="l_th2" body2="l_th2_3"/>
    <exclude body1="l_th2" body2="l_th2_slide"/>
    
    <exclude body1="l_th2_1" body2="l_base"/>
    <exclude body1="l_th2_1" body2="l_th2_2"/>
    <exclude body1="l_th2_1" body2="l_th2_3"/>
    <exclude body1="l_th2_1" body2="l_th2_slide"/>

    <exclude body1="l_th2_2" body2="l_base"/>
    <exclude body1="l_th2_2" body2="l_th2_3"/>
    <exclude body1="l_th2_2" body2="l_th2_slide"/>
    
    <exclude body1="l_th2_3" body2="l_base"/>
    <exclude body1="l_th2_3" body2="l_th2_slide"/>

    <exclude body1="l_th2_slide" body2="l_base"/>
  </contact>
  
  <equality>
    <connect body1="r_th2_3" body2="r_th2_slide" anchor="0 0.00027 0.0113" solimp="0.8 0.95 0.001" solref="0.001 1"/>
    <connect body1="r_ff1_1" body2="r_base_to_ff" anchor="-0.00328 -0.00436 0.00634" solimp="0.8 0.99 0.001" solref="0.001 1"/>
    <connect body1="r_mf1_1" body2="r_base_to_mf" anchor="-0.00326 0.00138 0.00756" solimp="0.8 0.99 0.001" solref="0.001 1"/>
    <connect body1="r_rf1_1" body2="r_base_to_rf" anchor="-0.00328 -0.00157 -0.00753" solimp="0.8 0.99 0.001" solref="0.001 1"/>
    <connect body1="r_lf1_1" body2="r_base_to_lf" anchor="-0.00330 0.00266 -0.00704" solimp="0.8 0.99 0.001" solref="0.001 1"/>
    <connect body1="r_th2_slide" body2="r_th1" anchor="0.0046 -0.0055 0.002" solimp="0.8 0.99 0.001" solref="0.001 1"/>
    <connect body1="l_th2_3" body2="l_th2_slide" anchor="0 0.00027 0.0113" solimp="0.8 0.95 0.001" solref="0.001 1"/>
    <connect body1="l_ff1_1" body2="l_base_to_ff" anchor="0.00328 -0.00436 0.00634" solimp="0.8 0.99 0.001" solref="0.001 1"/>
    <connect body1="l_mf1_1" body2="l_base_to_mf" anchor="0.00326 0.00138 0.00756" solimp="0.8 0.99 0.001" solref="0.001 1"/>
    <connect body1="l_rf1_1" body2="l_base_to_rf" anchor="0.00328 -0.00157 -0.00753" solimp="0.8 0.99 0.001" solref="0.001 1"/>
    <connect body1="l_lf1_1" body2="l_base_to_lf" anchor="0.00330 0.00266 -0.00704" solimp="0.8 0.99 0.001" solref="0.001 1"/>
    <connect body1="l_th2_slide" body2="l_th1" anchor="-0.0046 -0.0055 0.002" solimp="0.8 0.99 0.001" solref="0.001 1"/>
  </equality>



  <!-- <keyframe>
    <key name="home" qpos="1.4 2.4 -2 -2.2 0.57 1.6 1.4e-17 4.3e-15 0.35 -0.15 -0.4 0.0064 1.8 -1.4 -1.2 1.7 -1.5 -1.2 1.8 -1.4 -1.2 1.7 -1.5 -1.2 -1.3 2.3 -1.8 2 -0.28 -1.2 3.3e-17 4.6e-15 0.35 -0.15 -0.4 -0.0064 1.8 -1.4 -1.2 1.7 -1.5 -1.2 1.8 -1.4 -1.2 1.7 -1.5 -1.2"/>
  </keyframe> -->

</mujoco>

and the option setting:

  <option cone="elliptic" impratio="1"/>
  
  <option>
    <flag multiccd="enable"/>
  </option>

<option integrator="implicit"/>

the actuator setting:

<mujocoinclude>
  <actuator>
    <position name="r_x"  site="r_tcp_site" refsite="r_reference" gear="1 0 0 0 0 0" class="translation" kp="3000"/>
    <position name="r_y"  site="r_tcp_site" refsite="r_reference" gear="0 1 0 0 0 0" class="translation" dampratio="0.6"/>
    <position name="r_z"  site="r_tcp_site" refsite="r_reference" gear="0 0 1 0 0 0" class="translation" kp="3000"/>
    <position name="r_rx"  site="r_tcp_site" refsite="r_reference" gear="0 0 0 1 0 0" class="rotation"/>
    <position name="r_ry"  site="r_tcp_site" refsite="r_reference" gear="0 0 0 0 1 0" class="rotation"/>
    <position name="r_rz"  site="r_tcp_site" refsite="r_reference" gear="0 0 0 0 0 1" class="rotation"/>
    <position name="l_x"  site="l_tcp_site" refsite="l_reference" gear="1 0 0 0 0 0" class="translation" kp="3000"/>
    <position name="l_y"  site="l_tcp_site" refsite="l_reference" gear="0 1 0 0 0 0" class="translation" dampratio="0.4"/>
    <position name="l_z"  site="l_tcp_site" refsite="l_reference" gear="0 0 1 0 0 0" class="translation" kp="3000"/>
    <position name="l_rx"  site="l_tcp_site" refsite="l_reference" gear="0 0 0 1 0 0" class="rotation"/>
    <position name="l_ry"  site="l_tcp_site" refsite="l_reference" gear="0 0 0 0 1 0" class="rotation" dampratio="0.4"/>
    <position name="l_rz"  site="l_tcp_site" refsite="l_reference" gear="0 0 0 0 0 1" class="rotation"/>
    <position name="r_th1" joint="r_th1" kp="13" ctrlrange="0 1.57"/>
    <position name="r_ff" joint="r_ff1" kp="13" ctrlrange="1.75 3.11"/>
    <position name="r_mf" joint="r_mf1" kp="13" ctrlrange="1.71 3.07"/>
    <position name="r_rf" joint="r_rf1" kp="13" ctrlrange="1.77 3.08"/>
    <position name="r_lf" joint="r_lf1" kp="13" ctrlrange="1.73 3.05"/>
    <position name="r_th2" joint="r_th2" kp="13" ctrlrange="0.0 1.0"/>
    <position name="l_th1" joint="l_th1" kp="13" ctrlrange="0 1.57"/>
    <position name="l_ff" joint="l_ff1" kp="13" ctrlrange="1.75 3.11"/>
    <position name="l_mf" joint="l_mf1" kp="13" ctrlrange="1.71 3.07"/>
    <position name="l_rf" joint="l_rf1" kp="13" ctrlrange="1.77 3.08"/>
    <position name="l_lf" joint="l_lf1" kp="13" ctrlrange="1.73 3.05"/>
    <position name="l_th2" joint="l_th2" kp="13" ctrlrange="0.0 1.0"/>
  </actuator>
</mujocoinclude>

Actually, we have use the multi-ccd and adapted the solvers. It seems that if we use these actuators (the arms are controlled by refsite, and use the joint position control for hand), the implicit is more stable choice for simulation. Regarding the object, we only adjust the params of .add('joint', type='free', name=f'{config.name}_joint', damping=0.2) damping for more stable grasping.

I apologize if I provided too much information, which might have caused some confusion. Do you see any obvious issues with how I've set the parameters? If there's anything you need further explanation on, please feel free to ask! Thanks again for your response!

Balint-H · 2025-01-20T13:06:57Z

Balint-H
Jan 20, 2025
Collaborator

Hello,

One things that does "jump out" is the very high rolling and torsional friction. Can you try with a more standard set of variables? E.g. “1.2 0.005 0.0001”? If that slides too much you can consider raising impratio slightly. Also, you may want to decrease (try 0.5x) the finger actuator stiffness.

1 reply

gemcollector Jan 20, 2025
Author

Thanks for your further help! We tried your suggestions about standard set of variables of friction 1.2 0.005 0.0001 of class="right_hand", and decrease the finger actuator stiffness. But it's still a similar issue. Are there any other possible reasons? Thank you very much for your help!

yuvaltassa · 2025-01-22T23:25:55Z

yuvaltassa
Jan 22, 2025
Maintainer

Can you try reducing the actuator gains? They seem unreasonably high

4 replies

gemcollector Jan 28, 2025
Author

example.mov

Thanks for your reply! I adjusted the value of kp, but the robot behaves a bit oddly when it moves. What do you think might be the reason? How should I adjust it? Thank you very much for your help!

I list the actuator part below:

  <equality>
    <connect body1="r_th2_3" body2="r_th2_slide" anchor="0 0.00027 0.0113" solimp="0.8 0.95 0.001" solref="0.005 1"/>
    <connect body1="r_ff1_1" body2="r_base_to_ff" anchor="-0.00328 -0.00436 0.00634" solimp="0.95 0.99 0.001" solref="0.005 1"/>
    <connect body1="r_mf1_1" body2="r_base_to_mf" anchor="-0.00326 0.00138 0.00756" solimp="0.95 0.99 0.001" solref="0.005 1"/>
    <connect body1="r_rf1_1" body2="r_base_to_rf" anchor="-0.00328 -0.00157 -0.00753" solimp="0.95 0.99 0.001" solref="0.005 1"/>
    <connect body1="r_lf1_1" body2="r_base_to_lf" anchor="-0.00330 0.00266 -0.00704" solimp="0.95 0.99 0.001" solref="0.005 1"/>
    <connect body1="r_th2_slide" body2="r_th1" anchor="0.0046 -0.0055 0.002" solimp="0.95 0.99 0.001" solref="0.005 1"/>
    <connect body1="l_th2_3" body2="l_th2_slide" anchor="0 0.00027 0.0113" solimp="0.8 0.95 0.001" solref="0.005 1"/>
    <connect body1="l_ff1_1" body2="l_base_to_ff" anchor="0.00328 -0.00436 0.00634" solimp="0.95 0.99 0.001" solref="0.005 1"/>
    <connect body1="l_mf1_1" body2="l_base_to_mf" anchor="0.00326 0.00138 0.00756" solimp="0.95 0.99 0.001" solref="0.005 1"/>
    <connect body1="l_rf1_1" body2="l_base_to_rf" anchor="0.00328 -0.00157 -0.00753" solimp="0.95 0.99 0.001" solref="0.005 1"/>
    <connect body1="l_lf1_1" body2="l_base_to_lf" anchor="0.00330 0.00266 -0.00704" solimp="0.95 0.99 0.001" solref="0.005 1"/>
    <connect body1="l_th2_slide" body2="l_th1" anchor="-0.0046 -0.0055 0.002" solimp="0.95 0.99 0.001" solref="0.005 1"/>
  </equality>

  <actuator>
    <position name="r_x"  site="r_tcp_site" refsite="r_reference" gear="1 0 0 0 0 0" class="translation" kp="200"/>
    <position name="r_y"  site="r_tcp_site" refsite="r_reference" gear="0 1 0 0 0 0" class="translation" dampratio="0.6"/>
    <position name="r_z"  site="r_tcp_site" refsite="r_reference" gear="0 0 1 0 0 0" class="translation" kp="200"/>
    <position name="r_rx"  site="r_tcp_site" refsite="r_reference" gear="0 0 0 1 0 0" class="rotation" kp="50"/>
    <position name="r_ry"  site="r_tcp_site" refsite="r_reference" gear="0 0 0 0 1 0" class="rotation" kp="50" dampratio="0.2"/>
    <position name="r_rz"  site="r_tcp_site" refsite="r_reference" gear="0 0 0 0 0 1" class="rotation" kp="50"/>
    <position name="r_th1" joint="r_th1" kp="6" ctrlrange="0 1.57"/>
    <position name="r_ff" joint="r_ff1" kp="6" ctrlrange="1.75 3.11"/>
    <position name="r_mf" joint="r_mf1" kp="6" ctrlrange="1.71 3.07"/>
    <position name="r_rf" joint="r_rf1" kp="6" ctrlrange="1.77 3.08"/>
    <position name="r_lf" joint="r_lf1" kp="6" ctrlrange="1.73 3.05"/>
    <position name="r_th2" joint="r_th2" kp="6" ctrlrange="0.0 1.0"/>
    <position name="l_x"  site="l_tcp_site" refsite="l_reference" gear="1 0 0 0 0 0" class="translation" kp="200"/>
    <position name="l_y"  site="l_tcp_site" refsite="l_reference" gear="0 1 0 0 0 0" class="translation" dampratio="0.4"/>
    <position name="l_z"  site="l_tcp_site" refsite="l_reference" gear="0 0 1 0 0 0" class="translation" kp="200"/>
    <position name="l_rx"  site="l_tcp_site" refsite="l_reference" gear="0 0 0 1 0 0" class="rotation" kp="50"/>
    <position name="l_ry"  site="l_tcp_site" refsite="l_reference" gear="0 0 0 0 1 0" class="rotation" kp="50" dampratio="0.2"/>
    <position name="l_rz"  site="l_tcp_site" refsite="l_reference" gear="0 0 0 0 0 1" class="rotation" kp="50"/>
    <position name="l_th1" joint="l_th1" kp="6" ctrlrange="0 1.57"/>
    <position name="l_ff" joint="l_ff1" kp="6" ctrlrange="1.75 3.11"/>
    <position name="l_mf" joint="l_mf1" kp="6" ctrlrange="1.71 3.07"/>
    <position name="l_rf" joint="l_rf1" kp="6" ctrlrange="1.77 3.08"/>
    <position name="l_lf" joint="l_lf1" kp="6" ctrlrange="1.73 3.05"/>
    <position name="l_th2" joint="l_th2" kp="6" ctrlrange="0.0 1.0"/>
  </actuator>

  <keyframe>
    <key name="home" qpos="1.638 2.374 -1.718 -2.882 0.501 2.47 1.4e-17 4.3e-15 0.35 -0.15 -0.4 0.0064 1.8 -1.4 -1.2 1.7 -1.5 -1.2 1.8 -1.4 -1.2 1.7 -1.5 -1.2 -1.547 2.554 -1.95 2.452 -0.606 -2.092 3.3e-17 4.6e-15 0.35 -0.15 -0.4 -0.0064 1.8 -1.4 -1.2 1.7 -1.5 -1.2 1.8 -1.4 -1.2 1.7 -1.5 -1.2"/>
  </keyframe>

yuvaltassa Feb 12, 2025
Maintainer

What's the deal with the equality constraints? What is their purpose? Looks like the actuators and the constraints are fighting each other...

Stillwtm Feb 13, 2025

Thanks a lot for your reply! Here, we use equality constraints to simulate the closed chain mechanism on the finger.

Could you please explain where the conflict is?
BTW, we didn't use tendon because it seems to require setting a coefficient and needs to be aligned with the real machine. Or could you suggest any other methods to better simulate this closed chain mechanism?

yuvaltassa Feb 18, 2025
Maintainer

Ah, got it. I think you need some null space mechanism since you have so many dof's in the arm. A hacky way of doing this is to add some stiffness to all the arm joints which will try to bring the null space pose to the base pose. Of course these will fight the actuators so don't make them too strong. Another option is to use a differential IK package like https://github.com/kevinzakka/mink

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How to correctly set up collisions in MuJoCo? #2373

gemcollector Jan 19, 2025

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