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Hello list, I've been playing around with the telnet interface a bit, and have made a little trim-aid for us poor keyboard-users. More of that below. I also discovered some minor issues with fgfs: * It is not possible to have more then 1 active telnet connection at a time. * LaRCSim behaves very badly when setting wind values. It will pitch badly even when setting exactly the same value! * JSBSim's sense of /environment/wind-down-fps is inverted. (Personally I think it would be more intuitive to define vertical winds in the same direction as altitude. That is, positive is up. But if it has been chosen down, it should be down, not up.) Now on to the script. It is good to have a high degree of realism, but it would be nice if you could let go of the keyboard for a few seconds to take a sip of coffee, for example. :) It is possible to let the script run permanently, in which case it will keep the aircraft going perfectly straight without interaction. For added realism, you could start the script in level flight and disconnect it when it has stabilized. Experimenting tip: wait until the delay goes over 10 seconds, disconnect, and see how long it takes for the plane to roll over to one side. Unfortunately the script won't work very well with JSBSim. JSBSim's aileron trim is so insensitive that it can't even compensate for one notch of rudder. (IANAP, so I don't know how realistic that is.) YASim's aileron trim seems to behave like a secondary aileron control wrt to sensitivity. The script works fine with LaRCSim too, although it isn't really needed with LaRCSim. Usage: nc -vve ./autotrim <host> <port> (That is NetCat, compiled with GAPING_SECURITY_HOLE defined. http://freshmeat.net/projects/netcat/ ) Activating the telnet interface on fgfs: fgfs --props=socket,bi,5,<host>,<port>,tcp And finally, here it is: ===[ autotrim ]============================================================== #!/bin/sh exec awk -W interactive ' function abs(n) { if (n < 0) return -n return n } function sgn(n) { if (n < 0) return -1 if (n > 0) return 1 return 0 } function msg(m) { print m > "/dev/stderr" } function fail(m) { msg(m) exitcode = 1 exit exitcode } function datamode() { msg("entering data mode") print "data" msg("data mode entered") } function getproperty(p , ret) { msg("req: " p) print "get " p status = getline ret msg("result: " ret) return ret } function setproperty(p, v , dummy) { msg("set: " p " = " v) print "set " p " " v status = getline dummy } BEGIN { # user parameters req_roll = 0 # requested roll (deg) clim = 2 # control limit w/ aileron deflection (deg) lim = 3 # control limit w/ zero aileron (deg) min_delay = 0 # minimum iteration delay (sec) max_delay = 30 # maximum iteration delay (sec) damping = 10 # amount of roll damping (differentiator) effect center_pull = 10 # amount of center pull center_int = 1 # amount of deflection-off-center integration ailcenter = 1 # rate of aileron-to-trim transfer rr_limit = 0.002 # roll rate limit for delay increase (deg/iteration) dspd = 1 # maximum amount of time increase (sec/iteration) k = 1 # output amplification roll_prop = "/orientation/roll-deg" ail_prop = "/controls/aileron" output_prop = "/controls/aileron-trim" datamode() control = getproperty(output_prop) / k delay = 1 #sec while(1) { if (delay > max_delay) delay = max_delay if (delay < min_delay) delay = min_delay if (delay < 0) delay = 0 msg("delay: " delay) if (delay >= 1) system("sleep " int(delay)) last_roll = roll roll = getproperty(roll_prop) - req_roll if (status <= 0) fail("Connection lost.") if (roll > -lim && roll < lim) { ail = getproperty(ail_prop) if (status <= 0) fail("Connection lost.") if (ail > -0.01 && ail < 0.01) { if (manual) { manual = 0 last_roll = roll } dr = last_roll - roll delay = delay + dspd - dspd * 0.5 * (rr_limit + abs(dr)) / rr_limit msg("factor: " 0.5 * (rr_limit + abs(dr)) / rr_limit) msg("delay: " delay) control += dr * damping / 1000 tmp_trim = roll / 10000 control -= tmp_trim * center_int / 2 msg("int: " dr * damping / 100) msg("ctr: " tmp_trim) setproperty(output_prop, (control - tmp_trim * center_pull) * k) } else if ( roll > -clim && roll < clim) { if (delay > 2) delay-- msg("ail: " ail * ailcenter / 100) control += ail / 10 setproperty(output_prop, control * k) manual = 1 } else { manual = 1 } } else { manual = 1 } } } #END { # if (exitcode) exit exitcode # # other code #} ' 2> /dev/tty ============================================================================= Final notes: It was tested with mawk 1.3.3 under Linux. If you get it to work with gawk (should be compatible but the interactive unbuffered mode might be a problem) please post the required changes. Although I wrote it as a trim aid, with some tweaking of values it seems to perform surprisingly well as an external autopilot. Anyway, have fun playing with it! - -- Regards, "I RADIS, do you?" =Martin= http://www.iradis.org/ PGP: FE87448B DDF8 677C 9244 D119 4FE0 AE3A 37CF 3458 FE87 448B From: Martin van Beilen <[EMAIL PROTECTED]> To: [EMAIL PROTECTED] Subject: Aileron trim aid. X-S-Issue: [EMAIL PROTECTED] 2002/02/16 00:19:18 582dcc583820882fe069c53a8f871bb9 -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.6 (GNU/Linux) iEYEARECAAYFAjxtl34ACgkQN880WP6HRItDywCfdCWnDKFPsA4OudR/1gz0xyFC MdAAnA8u5Eqq+sQg0AsdyxGaSksOHzrA =q06E -----END PGP SIGNATURE----- _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
