Re: Lag filter implementation

Jon Berndt wrote:

>>I am implementing a RC UAV in FlightGear and need a little help with
>>the control system...
>>
>>The control system is fly-by-wire, with a receiver and standard RC servos.
>>The servo response is similar to a first order lag, so I am using a
>>lag-filter with C1 = 600.
>>
>>This is the elevator command system:
>>
>><COMPONENT NAME="Pitch Trim Sum" TYPE="SUMMER">
>>       INPUT        fcs/elevator-cmd-norm
>>       INPUT        fcs/pitch-trim-cmd-norm
>>       CLIPTO       -1 1
>></COMPONENT>
>><COMPONENT NAME="Elevator Control" TYPE="AEROSURFACE_SCALE">
>>       INPUT       fcs/pitch-trim-sum
>>       MIN          -20
>>       MAX          20
>>       GAIN         0.01745
>></COMPONENT>
>><COMPONENT NAME="Elevator Actuator" TYPE="LAG_FILTER">
>>       INPUT      ................
>>       C1            600
>>       OUTPUT    fcs/elevator-pos-rad
>></COMPONENT>
>>
>>
>>
>>What should the input be for the lag filter?
>>    
>>
>
>The component can be addressed by the use of a property, whose name is created by using
>the name of the component, making it all lower-case, and replacing spaces with a "-". So.
>the "Elevator Control" component would be referenced by the property: "elevator-control".
>This would be the input of your elevator actuator (after being prefixed with "fcs/"):
>
><COMPONENT NAME="Elevator Actuator" TYPE="LAG_FILTER">
>       INPUT      fcs/elevator-control
>       C1            600
>       OUTPUT    fcs/elevator-pos-rad
></COMPONENT>
>
>  
>
>>Should there be an output from the elevator control?
>>    
>>
>
>No. There should only be one output specification, and it should be from the last
>component in the chain of components. In your case, above, the elevator-pos-rad would be
>set each pass to the correct value. So, I would expect that somewhere in your aerodynamic
>specification you would have a reference to the property "fcs/elevator-pos-rad".
>
>I hope this helps!
>  
>
Thanks a lot for that! It worked almost immediately (little bug with 
aileron control.... solved now)




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