Rotor torque being multiplied by a moment arm?

[seanmcleod]

In the hexarotor and quadrotor models why is the net torque being multiplied by a moment arm?

px4-jsbsim-bridge/models/hexarotor_x/hexarotor_x.xml

Lines 586 to 597 in 263da94

	<axis name="YAW">
	<function name="aero/test_yaw">
	<description>Test Yaw</description>
	<sum>
	<product>
	<property>fcs/net_torque</property>
	<value>2.53</value><!-- Moment arm in feet -->
	</product>
	<property>fcs/torque_bypass</property>
	</sum>
	</function>
	</axis>

[Jaeyoung-Lim]

@mvacanti Could you share any insights?

[mvacanti]

@seanmcleod & @Jaeyoung-Lim Good catch. This is a holdover from previous work. Should be:

 <axis name="YAW"> 
     <function name="aero/rotor_yaw"> 
     <description>Rotor Yaw</description> 
     <sum> 
         <property>fcs/net_torque</property> 
         <property>fcs/torque_bypass</property> 
     </sum> 
   </function> 
 </axis> 

[seanmcleod]

What are fcs/torque_bypass and fcs/lift_bypass[x] for?

[mvacanti]

@seanmcleod these were properties I was using to test performance in JSBSim via telnet / scripts to evaluate model performance. It allowed me to 1. Isolate PX4 outputs in respect to vehicle movement (hold vehicle stationary or cause it to move in manner controlled explicitly by JSBSim) 2. Introduce disruptions to observe PX4 response. Can be simplified but believe the above are valuable uses.

[seanmcleod]

@mvacanti so maybe they're not named ideally? Maybe something like external_torque_disturbance?

I had searched through the rest of the model files and also the bridge source code for references and couldn't find any.

[mvacanti]

@seanmcleod yes they could be renamed - I chose bypass as it was bypassing PX4 commands. There should not be any references to the properties as I was strictly utilizing them through JSBSim Telnet or the script files (not published here) - though if they cause confusion than they should be removed.

[seanmcleod]

@mvacanti yep I meant since I couldn't find any references to them in the rest of the repo it was difficult to figure out what they were being used for so was just guessing based on the bypass in the names.

Wouldn't necessarily remove them, rather add a comment in the xml explaining what they can be used for and possibly rename them.