Adding a joint

[Gmirabile97]

I added these lines in "quadrotor_with_asus_with_hokuyo_utm30lx.urdf.xacro" in order to move the camera.

<link name="movable_link">
<visual>
<origin rpy="${M_PI/2} 0 0" xyz="0 0 -0.03" />
<geometry>
<cylinder radius="0.02" length="0.01" />
</geometry>
</visual>
<collision>
<origin rpy="${M_PI/2} 0 0" xyz="0 0 -0.03" />
<geometry>
<cylinder radius="0.02" length="0.01" />
</geometry>
</collision>
</link>

<joint name="movable_camera_joint" type="revolute">
<origin xyz="0 0 -0.1" rpy="0.0 0.0 0.0" />
<parent link="base_link" />
<child link="movable_link"/>
<axis xyz="1 0 0" />
<limit upper="0" lower="${-M_PI/2}" velocity="1.0" effort="1.0" />
</joint>

<xacro:joint_standard_transmission name="movable_camera_joint" />

When i launch "roslaunch hector_moveit_exploration_mod explore.launch", this is the error

hector_explorer_mod: /opt/ros/noetic/include/moveit/robot_state/robot_state.h:169: void moveit::core::RobotState::setVariablePositions(const std::vector<double>&): Assertion robot_model_->getVariableCount() <= position.size() failed.

Any help??