On Tuesday 03 February 2004 02:23, Jim Wilson wrote: > "Curtis L. Olson" <[EMAIL PROTECTED]> said: > > For everyone: I've integrated this into a larger document which attempts > > to explain the basic ideas behind control theory and then describes the > > specific PID algorithm we have implimented for FlightGear. This > > information isn't strictly necessary for building aircraft specific > > autopilot configurations, but it's such cool stuff it's worth mentioning. > > :-) > > It is indeed! Is the altitude hold working for you? I'm finding that the > first stage is outputing values that ocilate from max to min and back in > probably 5 or 6 (not timed yet) cycles. Anyway, I haven't looked at the > code or adjusted any of the parameters yet. I just wanted to know if maybe > it's something unique to my setup before messing with numbers. > > Best, > > Jim
I started with putting the generic AP in the TSR2 and got similar behaviour. I haven't had a chance to see the docs yet but I've got a reasonable alt hold by reducing Kp & Ti, quite drastically. <!-- Altitude hold. 2 stage cascade controller. --> <!-- Stage #1 sets target rate of climb based on diff between current alt --> <!-- and target altitude. --> <pid-controller> <name>Altitude Hold (Altimeter based) Stage 1</name> <debug>false</debug> <enable> <prop>/autopilot/locks/altitude</prop> <value>altitude-hold</value> </enable> <input> <prop>/instrumentation/altimeter/indicated-altitude-ft</prop> </input> <reference> <prop>/autopilot/settings/target-altitude-ft</prop> </reference> <output> <prop>/autopilot/internal/target-climb-rate-fps</prop> </output> <config> <Kp>0.1</Kp> <!-- proportional gain --> <beta>1.0</beta> <!-- input value weighing factor --> <alpha>0.1</alpha> <!-- low pass filter weighing factor --> <gamma>0.0</gamma> <!-- input value weighing factor for --> <!-- unfiltered derivative error --> <Ti>20.0</Ti> <!-- integrator time --> <Td>0.00001</Td> <!-- derivator time --> <u_min>-40.0</u_min> <!-- minimum output clamp --> <u_max>40.0</u_max> <!-- maximum output clamp --> </config> </pid-controller> Obviously, I've upped the u_min & u_max here too. Heh! - I'll get the docs tomorrow... LeeE _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel