Adding rudder control to HITL standard VTOL fixed-wing

PX4 Autopilot VTOL 🚁
1

Hi there,

I was try to add rudder control to the HIL standard VTOL airframe, but it did not work. The following steps were what I have done, I edited the standard_vtol_hitl.sdf file.

At the rudder plugin, I added the <control_joint_name>

  <plugin name="rudder" filename="libLiftDragPlugin.so">
  <a0>0.0</a0>
  <cla>4.752798721</cla>
  <cda>0.6417112299</cda>
  <cma>0.0.</cma>
  <alpha_stall>0.3391428111</alpha_stall>
  <cla_stall>-3.85</cla_stall>
  <cda_stall>-0.9233984055</cda_stall>
  <cma_stall>0</cma_stall>
  <cp>-0.5 0 0.05</cp>
  <area>0.02</area>
  <air_density>1.2041</air_density>
  <forward>1 0 0</forward>
  <upward>0 1 0</upward>
  <link_name>base_link</link_name>
  <control_joint_name> 
     rudder_joint 
  </control_joint_name> 
  <control_joint_rad_to_cl>4.0</control_joint_rad_to_cl>
  <robotNamespace></robotNamespace>
  <windSubTopic>world_wind</windSubTopic>
</plugin>

Then in the channel, I added the channel for rudder with input_index of 8:

      <channel name="rudder">
      <input_index>8</input_index>
      <input_offset>0</input_offset>
      <input_scaling>1</input_scaling>
      <zero_position_disarmed>0</zero_position_disarmed>
      <zero_position_armed>0</zero_position_armed>
      <joint_control_type>position_kinematic</joint_control_type>
      <joint_name>rudder_joint</joint_name>
    </channel>

However, when I run the HIL, the rudder control is not performed when I input yaw control on my joystick. I have tried to change the input_index to 7, then I think it works, however I would lost my elevator control which also has input_index of 7.

I am wondering if I did any step wrong or I missed any step.
Thanks in advance!

Barry