On Wednesday 04 February 2004 21:52, Roy Vegard Ovesen wrote: > On Wed, 4 Feb 2004 00:48:00 +0000, Lee Elliott > > <[EMAIL PROTECTED]> wrote: > > <!-- 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... > > Some notes on tuning cascade controllers: > > When tuning cascade controllers it is common practice to first tune the > inner loop or the secondary controller in Lee's example that would be the > vertical speed controller, and then tune the outer loop or the primary > controller.
That's interesting - I concentrated on getting good values in the output from the first stage before I considered looking at the second, which I don't think I touched in the end. I figured I'd need reasonable data going into the second stage if I were to make any sense of what it did. LeeE _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
