No transform from [base_link] to [odom]

edit

I'm trying to visualize my robot in Rviz and I'm getting several errors:

• Global Status: Fixed Frame: No tf data. Actual error: Fixed Frame [odom] does not exist
• Robot Model: base_link: No transform from [base_link] to [odom]
• Imu: Transform [sender=unknown_publisher] For frame [base_link]: Fixed Frame [odom] does not exist

Why am I getting these errors?

My robot is a simple cylinder with the URDF:

<?xml version="1.0" encoding="UTF-8"?>
<robot xmlns:xacro="http://www.ros.org/wiki/xacro" name="robot">
    <xacro:property name="torso_radius" value="0.075" />
    <xacro:property name="torso_height" value="0.16" />
    <link name="base_link">
        <visual>
            <geometry>
                <cylinder length="${torso_height}" radius="${torso_radius}" />
            </geometry>
            <origin xyz="0 0 ${torso_height/2}" rpy="0 0 0" />
        </visual>
    </link>
</robot>

It outputs odometry messages like:

header: 
  seq: 10
  stamp: 
    secs: 1496543906
    nsecs: 963784933
  frame_id: /odom
child_frame_id: /base_link
pose: 
  pose: 
    position: 
      x: 0.082
      y: 0.001
      z: 0.0
    orientation: 
      x: 0.0
      y: 0.0
      z: 0.0234978370806
      w: 0.999723887707
  covariance: [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
twist: 
  twist: 
    linear: 
      x: 0.002
      y: 0.0
      z: 0.0
    angular: 
      x: 0.0
      y: 0.0
      z: -0.009
  covariance: [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]

and IMU messages like:

header: 
  seq: 165
  stamp: 
    secs: 1496543986
    nsecs: 493674993
  frame_id: base_link
orientation: 
  x: 0.0
  y: 0.0
  z: 0.0
  w: 1.0
orientation_covariance: [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
angular_velocity: 
  x: 0.0
  y: 0.0
  z: 0.0
angular_velocity_covariance: [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
linear_acceleration: 
  x: -0.5
  y: -0.24
  z: 9.77
linear_acceleration_covariance: [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]

I'm launching Rviz with the launch file:

<launch>
    <arg name="model" default="$(find myrobot_description)/urdf/robot.urdf.xacro"/>
    <param name="robot_description" command="$(find xacro)/xacro --inorder $(arg model)" />
    <node name="robot_state_publisher" pkg="robot_state_publisher" type="state_publisher" />
    <arg name="gui" default="true" />
    <arg name="rvizconfig" default="$(find myrobot_description)/rviz/urdf.rviz" />
    <param name="robot_description" command="$(find xacro)/xacro --inorder $(arg model)" />
    <param name="use_gui" value ...