model.sdf

<?xml version="1.0"?>

<sdf version="1.6">
  <model name='DeliveryRobot'>

    <!-- TODO(MXG): Find actual physical properties for DeliveryRobot -->
    <plugin name="slotcar" filename="libslotcar.so">

      <!-- Forward / Backward -->
      <nominal_drive_speed>0.7</nominal_drive_speed>
      <nominal_drive_acceleration>0.5</nominal_drive_acceleration>
      <!-- Theoretical no-slip limit with current suspension: 0.8 -->
      <max_drive_acceleration>0.75</max_drive_acceleration>

      <!-- Turning -->
      <nominal_turn_speed>0.6</nominal_turn_speed>
      <!-- Note: The official maximum turn acceleration value is 0.25, but that
           seems to be too small for the simulated DeliveryRobot to do course
           corrections while driving, so it ends up swaying erratically. Using
           this larger value helps keep DeliveryRobot's course stable. -->
      <nominal_turn_acceleration>1.5</nominal_turn_acceleration>
      <!-- Theoretical no-slip limit with current suspension: 2.166666... -->
      <max_turn_acceleration>2.0</max_turn_acceleration>

      <stop_distance>0.75</stop_distance>
      <stop_radius>0.75</stop_radius>

      <!-- Can the robot drive backwards -->
      <reversible>true</reversible>

      <!-- Battery params -->
      <nominal_voltage>24.0</nominal_voltage>
      <nominal_capacity>40.0</nominal_capacity>
      <charging_current>8.8</charging_current>

      <!-- Physical params -->
      <mass>70.0</mass>
      <inertia>40.0</inertia>
      <friction_coefficient>0.22</friction_coefficient>

      <!-- Power systems -->
      <nominal_power>20.0</nominal_power>

    </plugin>

    <link name="body">
      <pose>0 0 0 0 0 -1.57</pose>

      <inertial>
        <pose>0 0 0.201 0 0 0</pose>
        <mass>70</mass>
        <inertia>
          <ixx>5.1526</ixx>
          <iyy>2.4944</iyy>
          <izz>6.2829</izz>
        </inertia>
      </inertial>

      <visual name="body">
        <geometry>
          <mesh><uri>model://DeliveryRobot/meshes/body.obj</uri></mesh>
        </geometry>
      </visual>
      <collision name="body">
        <geometry>
          <mesh><uri>model://DeliveryRobot/meshes/body.obj</uri></mesh>
        </geometry>
      </collision>

      <visual name="WheelLeftFront">
        <pose>-0.220 -0.262 0.061 0 0 0</pose>
        <geometry>
          <mesh>
            <uri>model://DeliveryRobot/meshes/WheelMain.obj</uri>
          </mesh>
        </geometry>
      </visual>
      <collision name="front_caster_left">
        <pose>-.25 -.27 0.05 0 0 0</pose>
        <geometry>
          <sphere><radius>0.05</radius></sphere>
        </geometry>
        <surface>
          <friction>
            <torsional>
              <coefficient>0.0</coefficient>
            </torsional>
            <ode>
              <mu>0.0</mu>
              <mu2>0.0</mu2>
            </ode>
            <bullet>
              <friction>0.0</friction>
              <friction2>0.0</friction2>
              <rolling_friction>0.0</rolling_friction>
            </bullet>
          </friction>
        </surface>
      </collision>

      <visual name="WheelLeftBack">
        <pose>-0.220 0.334 0.061 0 0 0</pose>
        <geometry>
          <mesh>
            <uri>model://DeliveryRobot/meshes/WheelMain.obj</uri>
          </mesh>
        </geometry>
      </visual>
      <collision name="back_caster_left">
        <pose>-.25 .34 0.05 0 0 0</pose>
        <geometry>
          <sphere><radius>0.05</radius></sphere>
        </geometry>
        <surface>
          <friction>
            <torsional>
              <coefficient>0.0</coefficient>
            </torsional>
            <ode>
              <mu>0.0</mu>
              <mu2>0.0</mu2>
            </ode>
            <bullet>
              <friction>0.0</friction>
              <friction2>0.0</friction2>
              <rolling_friction>0.0</rolling_friction>
            </bullet>
          </friction>
        </surface>
      </collision>

      <visual name="WheelRightFront">
        <pose>0.217 -0.262 0.061 0 0 0</pose>
        <geometry>
          <mesh>
            <uri>model://DeliveryRobot/meshes/WheelMain.obj</uri>
          </mesh>
        </geometry>
      </visual>
      <collision name="front_caster_right">
        <pose>.25 -.27 0.05 0 0 0</pose>
        <geometry>
          <sphere><radius>0.05</radius></sphere>
        </geometry>
        <surface>
          <friction>
            <torsional>
              <coefficient>0.0</coefficient>
            </torsional>
            <ode>
              <mu>0.0</mu>
              <mu2>0.0</mu2>
            </ode>
            <bullet>
              <friction>0.0</friction>
              <friction2>0.0</friction2>
              <rolling_friction>0.0</rolling_friction>
            </bullet>
          </friction>
        </surface>
      </collision>

      <visual name="WheelRightBack">
        <pose>0.217 0.334 0.061 0 0 0</pose>
        <geometry>
          <mesh>
            <uri>model://DeliveryRobot/meshes/WheelMain.obj</uri>
          </mesh>
        </geometry>
      </visual>
      <collision name="back_caster_right">
        <pose>.25 .34 0.05 0 0 0</pose>
        <geometry>
          <sphere><radius>0.05</radius></sphere>
        </geometry>
        <surface>
          <friction>
            <torsional>
              <coefficient>0.0</coefficient>
            </torsional>
            <ode>
              <mu>0.0</mu>
              <mu2>0.0</mu2>
            </ode>
            <bullet>
              <friction>0.0</friction>
              <friction2>0.0</friction2>
              <rolling_friction>0.0</rolling_friction>
            </bullet>
          </friction>
        </surface>
      </collision>
    </link>

    <link name="suspension_tire_left">
      <!-- This is a dummy link that's used to connect a suspension (prismatic
           joint) to the tire axis (revolute joint) -->
      <pose>0 0.26 0.10 0 0 0</pose>
      <inertial>
        <mass>1.00</mass>
        <inertia>
          <ixx>1.00</ixx>
          <iyy>1.00</iyy>
          <izz>1.00</izz>
        </inertia>
      </inertial>
    </link>

    <joint name="joint_suspension_tire_left" type="prismatic">
      <parent>body</parent>
      <child>suspension_tire_left</child>
      <axis>
        <xyz>0 0 1</xyz>
        <dynamics>
          <damping>500</damping>
          <spring_reference>-0.09</spring_reference>
          <spring_stiffness>2000</spring_stiffness>
        </dynamics>
      </axis>
      <physics>
        <ode>
          <implicit_spring_damper>true</implicit_spring_damper>
        </ode>
      </physics>
    </joint>

    <link name="tire_left">
      <pose>0 0.26 0.10 0 0 0</pose>

      <inertial>
        <pose>0 0 0 0 0 0</pose>
        <mass>5.0</mass>
        <!--<mass>2.60595111</mass>-->
        <!-- Note: These calculated MOI values seem to be too small for ODE's
                   numerical precision and make the robot slip. So instead we 
                   use some higher values (x10) which seem to get better 
                   behavior-->
        <!--inertia>
          <ixx>0.00757897446874</ixx>
          <iyy>0.01302975553365</iyy>
          <izz>0.00757897446874</izz>
        </inertia-->
        <!--
        <inertia>
          <ixx>0.1302975553365</ixx>
          <iyy>0.0757897446874</iyy>
          <izz>0.0757897446874</izz>
        </inertia>
        -->
        <inertia>
          <ixx>0.757897446874</ixx>
          <iyy>1.302975553365</iyy>
          <izz>0.757897446874</izz>
        </inertia>
      </inertial>

      <visual name="WheelSideLeft">
        <pose>0 0.0 0.0 0 0 -1.57</pose>
        <geometry>
          <mesh>
            <uri>model://DeliveryRobot/meshes/WheelSide.obj</uri>
          </mesh>
        </geometry>
      </visual>
      <collision name="tire_left">
        <geometry>
          <sphere><radius>0.06137</radius></sphere>
        </geometry>
        <surface>
          <contact>
            <ode>
              <kp>10000000.0</kp>
              <kd>1.0</kd>
            </ode>
          </contact>
        </surface>
      </collision>
    </link>

    <joint name="joint_tire_left" type="revolute">
      <parent>suspension_tire_left</parent>
      <child>tire_left</child>
      <axis>
        <xyz>0 1 0</xyz>
      </axis>
    </joint>

    <link name="suspension_tire_right">
      <!-- This is a dummy link that's used to connect a suspension (prismatic
           joint) to the tire axis (revolute joint) -->
      <pose>0 -0.26 0.10 0 0 0</pose>
      <inertial>
        <mass>1.00</mass>
        <inertia>
          <ixx>1.00</ixx>
          <iyy>1.00</iyy>
          <izz>1.00</izz>
        </inertia>
      </inertial>
    </link>

    <joint name="joint_suspension_tire_right" type="prismatic">
      <parent>body</parent>
      <child>suspension_tire_right</child>
      <axis>
        <xyz>0 0 1</xyz>
        <dynamics>
          <damping>500</damping>
          <spring_reference>-0.09</spring_reference>
          <spring_stiffness>2000</spring_stiffness>
        </dynamics>
      </axis>
      <physics>
        <ode>
          <implicit_spring_damper>true</implicit_spring_damper>
        </ode>
      </physics>
    </joint>

    <link name="tire_right">
      <pose>0 -0.26 0.10 0 0 0</pose>

      <inertial>
        <pose>0 0 0 0 0 0</pose>
        <!--<mass>2.60595111</mass>-->
        <mass>5.0</mass>
        <!-- Note: These calculated MOI values seem to be too small for ODE's
                   numerical precision and make the robot slip. So instead we 
                   use some higher values (x10) which seem to get better 
                   behavior-->
        <!--inertia>
          <ixx>0.00757897446874</ixx>
          <iyy>0.01302975553365</iyy>
          <izz>0.00757897446874</izz>
        </inertia-->
        <!--
        <inertia>
          <ixx>0.1302975553365</ixx>
          <iyy>0.0757897446874</iyy>
          <izz>0.0757897446874</izz>
        </inertia>
        -->
        <inertia>
          <ixx>0.757897446874</ixx>
          <iyy>1.302975553365</iyy>
          <izz>0.757897446874</izz>
        </inertia>
      </inertial>

      <visual name="WheelSideRight">
        <pose>0 0.0 0.0 0 0 -1.57</pose>
        <geometry>
          <mesh>
            <uri>model://DeliveryRobot/meshes/WheelSide.obj</uri>
          </mesh>
        </geometry>
      </visual>
      <collision name="tire_right">
        <geometry>
          <sphere><radius>0.06137</radius></sphere>
        </geometry>
        <surface>
          <contact>
            <ode>
              <kp>10000000.0</kp>
              <kd>1.0</kd>
            </ode>
          </contact>
        </surface>
      </collision>
    </link>

    <joint name="joint_tire_right" type="revolute">
      <parent>suspension_tire_right</parent>
      <child>tire_right</child>
      <axis>
        <xyz>0 1 0</xyz>
      </axis>
    </joint>

  </model>
</sdf>