public/so-101-urdf/joints_properties.xml

<default>
    <default class="sts3215">
        <geom contype="0" conaffinity="0"/>
        <joint damping="0.60" frictionloss="0.052" armature="0.028"/>
        <position kp="17.8" kv="0.0" forcerange="-3.35 3.35"/>
    </default>
    <default class="backlash">
        <!-- +/- 0.5° of backlash -->
        <joint damping="0.01" frictionloss="0" armature="0.01" limited="true"
            range="-0.008726646259971648 0.008726646259971648"/>
    </default>
</default>