Robotics-Project/bicycle.urdf at main · MertAltug/Robotics-Project · GitHub

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<?xml version="1.0"?>
<robot name="bicycle_robot">

  <!-- World link -->
  <link name="world"/>

  <!-- Chassis -->
  <link name="base_link">
    <inertial>
      <mass value="1.0"/>
      <origin xyz="0 0 0.15"/>
      <inertia ixx="0.1" ixy="0" ixz="0" iyy="0.1" iyz="0" izz="0.1"/>
    </inertial>
    <visual>
      <origin xyz="0 0 0.15"/>
      <geometry>
        <box size="0.6 0.1 0.1"/>
      </geometry>
      <material name="blue">
        <color rgba="0.3 0.3 0.8 1"/>
      </material>
    </visual>
    <collision>
      <origin xyz="0 0 0.15"/>
      <geometry>
        <box size="0.6 0.1 0.1"/>
      </geometry>
    </collision>
  </link>

  <!-- Free-floating joint -->
  <joint name="floating_base_joint" type="floating">
    <parent link="world"/>
    <child link="base_link"/>
  </joint>

  <!-- Rear wheel (remains fixed to the chassis) -->
  <joint name="rear_wheel_joint" type="fixed">
    <parent link="base_link"/>
    <child link="rear_wheel"/>
    <origin xyz="-0.3 0 0.1" rpy="1.5707 0 0"/>
  </joint>
  <link name="rear_wheel">
    <visual>
      <geometry>
        <cylinder radius="0.1" length="0.05"/>
      </geometry>
      <material name="black"/>
    </visual>
    <collision>
      <geometry>
        <cylinder radius="0.1" length="0.05"/>
      </geometry>
    </collision>
  </link>

  <!-- Front Steering Joint (Revolute) -->
  <!-- This joint allows the fork to turn -->
  <joint name="front_steering_joint" type="revolute">
    <parent link="base_link"/>
    <child link="front_fork"/>
    <origin xyz="0.3 0 0.15"/> <!-- Position of the steering axis -->
    <axis xyz="0 0 1"/> <!-- Steers around the Z-axis of the fork's frame -->
    <limit lower="-0.7" upper="0.7" effort="10" velocity="10"/>
  </joint>

  <link name="front_fork"/> <!-- A virtual link for the fork -->

  <!-- Front Wheel (Fixed to the moving fork) -->
  <joint name="front_wheel_joint" type="fixed">
    <parent link="front_fork"/> <!-- Attach wheel to the fork -->
    <child link="front_wheel"/>
    <origin xyz="0 0 -0.05" rpy="1.5707 0 0"/> <!-- Position relative to the fork -->
  </joint>
  <link name="front_wheel">
    <visual>
      <geometry>
        <cylinder radius="0.1" length="0.05"/>
      </geometry>
      <material name="black"/>
    </visual>
    <collision>
      <geometry>
        <cylinder radius="0.1" length="0.05"/>
      </geometry>
    </collision>
  </link>

</robot>