Re: [Paparazzi-devel] 127 ways to reverse a servo

[Martin P]

Thank you! And thank you, Chris.
This is very valuable information. 
I think I got it now, reversed the axis in the servo section and in the radio 
conf. 

Martin

-------- Original-Nachricht --------
> Datum: Tue, 21 Jul 2009 14:59:41 +0200
> Von: Gautier Hattenberger <address@hidden>
> An: address@hidden
> Betreff: Re: [Paparazzi-devel] 127 ways to reverse a servo

> Hello,
> 
> You can't change the sign of the control loop. It's a negative feedback 
> control, and the way it is written, the coefficients have to be negative.
> 
> Your problem is that your radio xml file and the autopilot doesn't match 
> when they send orders, so your commands will be different between manual 
> and AUTO1/2 (and there is no way to make it work!). To work properly, be 
> sure that your RC gives the min value when turning right (roll) and 
> going down (pitch) (http://paparazzi.enac.fr/wiki/Radio_Control). Be 
> careful that all your RC channels are not set to reverse. When it's 
> done, change the min/max value in the airframe xml file (servo section) 
> so that all surfaces move in the right direction in manual. Now, if they 
> are reversed in AUTO1/2, change the command laws (command_law section) 
> but it shouldn't be necessary.
> 
> If I have not missed any step, this leaves only one (good) way to do it ;)
> 
> Gautier
> 
> 
> Martin P a écrit :
> > Hi, 
> >
> > I am still ground testing only. 
> > I was happy to see that my ailerons moved in the correct direction in
> manual mode. 
> > When the ailerons moved in the wrong direction in AUTO1, I changed the
> sign of ROLL_ATTITUDE_GAIN from negative to positive and saw that the
> ailerons moved correctly when I rolled the aircraft left and right. All right,
> but then I started the simulator and the plane went in a small circle.
> ROLL_ATTITUDE_GAIN back to negative, and it moved nicely in the simulator but
> wrong again in the real plane. 
> >
> > Well, before venturing into the air, I would like to have everything
> correct. Even when I plan to do only AUTO1 flights, there is a chance that I
> lose the 35MHz connection (interference, broken PPM wire,...) and fall into
> AUTO2. Then I would like the plane to fly and not to crash. 
> >
> > What possibilities are there to reverse an axis? 
> >
> > 1) in the transmitter  
> > 2) in the radio xml-file 
> > 3) in the servos section 
> > 4) in the RC commands 
> > 5) in the command laws 
> > 6) in the outer loop 
> > 7) in the inner loop 
> >
> > 1) and 2) should be the same, but when I tried it with the throttle, it
> wasn't. 
> >
> > 2 to the power of 7 is 128, minus the setting you have, gives 127 ways
> to reverse a servo, probably 126 of them are wrong ... pretty confusing. 
> >
> > Does the simulator tell it right or is there something to reverse as
> well? 
> > Are there laws to reduce the number of cases, let's say that
> ROLL_ATTITUDE_GAIN and COURSE_PGAIN should have the same sign? 
> >
> > Greetings, Martin 
> >
> >
> > _______________________________________________
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> > http://lists.nongnu.org/mailman/listinfo/paparazzi-devel
> >   
> 
> 
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