<mujoco model="arm">
    <compiler angle="degree" coordinate="local" inertiafromgeom="true"/>
    <default>
        <geom conaffinity="1" condim="1" contype="1" margin="0.001" material="geom" rgba="0.8 0.6 .4 1" solimp=".8 .8 .01" solref=".02 1"/>
        <motor ctrllimited="true" ctrlrange="-.4 .4"/>
    </default>
    <option integrator="RK4" timestep="0.002"/>
    <visual>
        <map znear="0.02"/>
    </visual>
    <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" rgba="0.8 0.9 0.8 1" size="20 20 .125" type="plane"/>
        <body name="upper_arm_body" pos="0.0 0.0 3.0">
            <joint name="shoulder_joint" axis="0 1 0" limited="true" range="-5 45" />
            <geom name="upper_arm_geom" fromto="0.0 0.0 0.0 1.8 0.0 0.0"  size="0.09" type="capsule"/>
            <geom name="elbow" type="cylinder" fromto="1.8 0.09 0.0 1.8 -0.09 0.0" size="0.1" rgba=".3 .9 .3 .4"/>
            <site name="brachialis_u_insertion" pos="1.1 0.0 0.05" size="0.05"/>
            <site name="triceps_u_insertion" pos="0.45 0.0 -0.05" size="0.05"/>
            <body name="lower_arm_body" pos="1.8 0.0 0.0">
                <joint axis="0 1 0" damping="1" limited="true" name="elbow_joint" pos="0.0 0.0 0.0" range="-90 5"/>
                <geom fromto="-0.1 0.0 0.0 1.5 0.0 0.0" name="lower_arm_geom" size="0.09" type="capsule"/>
                <geom pos="1.5 0.0 0.1" size="0.2" type="sphere"/>
                <site name="brachialis_l_insertion" pos="0.3 0.0 0.05" size="0.05"/>
                <site name="triceps_l_insertion" pos="-0.1 0.0 -0.1" size="0.05" />
            </body>
        </body>
    </worldbody>
    <tendon>
        <spatial name="brachialis" width="0.05" rgba=".95 .3 .3 1" stiffness="1000">
            <site site="brachialis_u_insertion" />
            <geom geom="elbow" />
            <site site="brachialis_l_insertion" />
        </spatial>
        <spatial name="triceps" width="0.05" rgba=".95 .3 .3 1" stiffness="500">
            <site site="triceps_u_insertion" />
            <geom geom="elbow" />
            <site site="triceps_l_insertion" />
        </spatial>
    </tendon>
    <asset>
        <texture builtin="gradient" height="100" rgb1=".4 .5 .6" 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"/>
    </asset>
</mujoco>