Nice explanation. As a non-novice non-expert with a plain old joystick, I would prefer that when I engage the autopilot that the autopilot does its thing and my (untouched) joystick doesn't fight with it. Otherwise the autopilot is useless. So ignoring the joystick seems like the right thing to do.
Still, it'd be nice to be able to, for example, turn the plane for a few seconds to adjust heading while the wing leveler is on. i.e. overpower the autopilot temporarily. What would happen if the yoke movements were additive to the autopilot, similar to how they are additive to the current trim settings (and indeed the autopilot changes trim settings). Then even a slightly noisy joystick would only cause a tiny war between the user and autopilot. On 6/30/07, John Denker <[EMAIL PROTECTED]> wrote: > On 06/30/2007 09:52 AM, [EMAIL PROTECTED] wrote: > > An airliner some years ago crashed into the Everglades in Florida > > because the autopilot > > was unknowingly disengaged by accidental knee pressure on the Yoke as > > the pilot > > was getting out of his seat. Specs showed that the minimum 45 pounds > > pressure required was faulty. > > > > The aircraft had been in a holding pattern pending confirmation that the > > gear was down, since the > > indicator lamp was burned out and the spare broke upon attempted removal > > from its recessed > > location. Unknowingly the aircraft was slowly descending and the last > > thing on the voice > > recorder ws the co-pilot "Hey, there's something wrong with the > > instruments" when he > > noticed the altimeter showed just above ground level. > > > > If I understand the FG issue correctly, then I would think that a sudden > > movement of > > the Yoke could be used to disengage the autopilot. > > This is a tricky issue. > > One case that has to be considered is what happens when you > are /engaging/ the autopilot. In particular, suppose you > are in a long-winged glider in a steep turn, holding > tons of outside aileron to compensate for the overbanking > tendency. You engage the autopilot, desiring that it > will maintain the turn. Then > -- in the real aircraft, you let go of the yoke and > it stays where it is. No problem. > -- in FG, you let go of the yoke and it springs back > to the center. That's a problem. > > On the other side of the same coin, suppose you want to > disengage the autopilot while the ailerons are deflected. > You really ought to deflect the joystick so that it matches > what the autopilot is doing with the yoke, before hitting > the autopilot disengage button. > > Similar considerations apply to the pitch axis and yaw axis. > Keep in mind the pilot who inadvertently snap-rolled a 747, > seriously injuring a couple of passengers, by disengaging the > autopilot without noticing that the autopilot was holding one > of the rudder pedals to the floor. > http://en.wikipedia.org/wiki/China_Airlines_Flight_006 > and references therein. > > > Note that there are four stages of sophistication among FG users: > a) Using the keyboard for primary flight control; > b) Using the mouse for primary flight control; > c) Using a plain old joystick for primary flight control; or > d) Using a joystick with force-feedback (or position servos) > for primary flight control. > > It is slightly peculiar that the problem is only serious in > stage (c). It does not arise in stage (b) because we can warp > the mouse to the desired position; we let the user deal with > the side effects of such warpage. > > Arguably the theoretically-ideal solution would be for everybody > to skip stage (c) and go directly to fully position-servoed > joysticks ... but that is not likely to happen anytime soon, > so for now we are still facing nontrivial problems at stage (c). > > Note that the problems are compounded by the fact that the naive > user does not know what to expect ... and indeed doesn't even > understand what he's seeing when a war breaks out between the > autopilot and the joystick. It just looks like something is > broken. Disabling the joystick when the autopilot is active > ends the war, but doesn't really solve the user's problem; he > just sees it as a different kind of brokenness. > > One half-baked idea I've been toying with involves animating a > /hand/ which is normally gripping the yoke. The joystick moves > the hand. When the autopilot is engaged, the joystick still moves > the hand, but the hand is not gripping the yoke. I'm not sure > how hard this would be to implement. In any case, it has some > conceptual value, providing a way to visualize the nature of the > problem, to some extent. > > This is an important topic to be discussing. Some of the recent > suggestions are commendable steps in the right direction, but I > reckon we are still one breakthrough removed from a complete > solution to the problem. > > ------------------------------------------------------------------------- > This SF.net email is sponsored by DB2 Express > Download DB2 Express C - the FREE version of DB2 express and take > control of your XML. No limits. Just data. Click to get it now. > http://sourceforge.net/powerbar/db2/ > _______________________________________________ > Flightgear-devel mailing list > Flightgear-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/flightgear-devel > -- Hans Fugal Fugal Computing ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
